Solar Empire

New Neutrino Telescope

2011-01-25T09:20:00.000-08:00

Apparently one of the newer NASA science projects is a 1.5 mile long neutrino detector, called Ice-Cube. In the antarctic, they will drill 86 holes, 2820m deep down to bedrock, and lower strings of detectors down the length of the hole.

Neutrinos are particles produced in fusion reactions. Neutrinos and antineutrinos are the chargeless analogs of electrons and positrons, and only interact with other matter via the weak nuclear force. Because the weak nuclear force is very weak, it is very improbable for neutrinos to interact with anything.

It is so rare that they interact that the Earth is largely transparent to their passage. Prior neutrino detecting experiments were built deep beneath the earth to block out all other forms of radiation. These detectors built up an image of the mantle of the sun: at midnight, on the other side of the world.

I imagine that NASA is interested in this telescope to probe deep into the heart of energetic phenomena like quasars. The gas, dust, and accretion disks would be transparent to neutrino passage, and you would see straight to the heart of fusion processes.

I wonder though if this is a telescope in the sense of being able to build up a focused image from the data, or if it can only build up a defocused accumulation of neutrino magnitude as a function of direction? After all, if a neutrino interacts with the top detector, it would be very amazing odds for it to interact with any of the others prior to flying out into space, even without taking into account the scattering nature of the detection.
Still cool regardless. We live in amazing times.

Source Article: http://www.networkworld.com/community/blog/massive-ice-bound-telescope-set-capture-elusi

PS:
Future professor: You failed your quals! To encourage a proper studious attitude for the retake, I banish you to the ice telescopes of Antarctica!
Future grad student: Nooooo!

New Webblog

2011-01-24T16:50:00.000-08:00

I have a new webblog site at http://www.amssolarempire.com/Blog

I am going to try going semi-professional here, and restart my blogging on a wordpress website. I’ll have more control, than with blogger, and I will also be able to use the site as a point of distribution for coding projects, files, and tutorials. This will enable me to share my projects more effectively.

Going forward, I hope to share my knowledge and enthusiasm for science and aerospace technology, and space exploration on a regular basis again.

I will attempt to duplicate posts on each site, at least for now.

Keepalive

2009-04-12T19:25:00.001-07:00

I do intend to keep this blog. After my term of employment, I should be allowed to blog again, and will resume. This post is to keep any automatic cleanup routine from deleting my blog.

Math Blues I

2007-04-29T16:21:00.000-07:00

Gaaah.

So I'm trying to figure out a bit about wave dynamics - namely how a wave can move in a collimated fashion, such as in a light ray or laser beam.

I was playing around with the wave equation a bit. I set up field sims for a 3d wave and advanced time, reproducing all sorts of interesting effects. Diffraction, reflection, interference, refraction ect.

Then something started bugging me - if you have a travelling wave, how do you get it so that it retains a collimated shape? It seems to me that the divergence of the gradient on a point outside the beam is going to be nonzero due to the difference between the zero and nonzero amplitudes inside and outside the beam, and so the region outside the beam should be sucking up energy and spreading the wave as it travels.

At first I thought it was just that I was looking at a scalar wave, and light is a more complicated vector wave operating off of different rules. But in my optics book, they eventually transform maxwells equations into a set of 6 scalar equations for the electric and magnetic field, and the same laplacian(field) = acceleration(field) behavior results.

Okay, so then I did some reading and discovered that beams usually have gaussian distribution of amplitude along the beam radius.

I want to be able to figure out how the amplitude's radial profile changes as you move along the wave. So I wanted to transform the wave equation into a different coordinate system moving with the beam.

laplacian(field(x,y,z)) = acceleration(field(x,y,z)) -> acceleration(field(x-vt,y,z)) = ???

and here's where I have to quit for today, I need to make dinner.

This better not be something that some old math god fart like Newton or Euler solved in 5 minutes while waiting for the coffee to brew.

Amazing! Amazing! Amazing!

2007-04-24T16:43:00.001-07:00

In the red-dwarf star system Gliese 581 (20 ly from the Solar System), a (probably) rocky planet has been discovered. It is orbiting within the region of the star system where liquid water can form. (It is a much closer and smaller band than exists in our own star system, but apparently this planet falls within it).

It just might be the first earth-like planet we've discovered (after our own, of course)!

http://www.zeenews.com/znnew/articles.asp?aid=367459&ssid=27&sid=ENV

The planet is estimated to be 50% larger than Earth. Furthermore, red dwarf systems are very long lived, so if there is liquid water on this planet, there is also a good time window for life to have formed (or form, later on).

http://www.dailymail.co.uk/pages/live/articles/technology/technology.html?in_article_id=450467&in_page_id=1965

Crazy Nuke Idea #1

2007-04-12T03:44:00.000-07:00

I don't know enough nuclear physics (yet - I intend to know everything someday, though I also understand on an intellectual level why this is impossible) to tell if this is a good idea or not, but I was thinking:

(digression)
The holy grail of nuclear power physics is nuclear fusion. Presumably we would never have to worry about energy again if we had fusion reactors. I think people assume this because of the abundance of hydrogen in the universe. While it's true that hydrogen is the most abundant element in the universe, we don't have any shortage of uranium or thorium (on earth).

However, these reactors appear to me to be extremely complicated rube goldbergs compared to the simplicity of our fission plants. They require giant magnetic plasma traps to keep plasma spinning in large evacuated chambers. They require creating enough fusion reactions with this plasma to allow for drawing enough energy off of it (how? I've heard either thermally or through some sort of magnetic induction) to turn some sort of electric generator to feed enough power back into the magnets to keep the reaction going. So far, we don't seem to have reached anywhere near enough fusion/input energy to get this to work. While I've read about reaching breakeven for scattered microseconds on research devices, it doesn't appear that we've reached it on average for any extended period of time on a device.

Furthermore, even when we get it to work, building and operating these plants sounds like a pain in the butt. You have an extremely unstable reaction that could stop sustaining itself if anything goes out of whack. You have massive construction costs for the magnetic coils and vacuum chambers. You probably have massive operating costs because of the attention that these devices will require by plasma physicists.

So … I don’t know how often I’ve heard the sentiment expressed: Fission is old, inefficient (??? Efficiency needs a lot of qualifiers to mean something, you know), and dirty. Fusion is clean, efficient (???), and much much better. It is the way of the future.

Why this sentiment if 1) We can’t get it to work yet, 2) When we do get it to work, it will almost certainly be more complicated and expensive to operate, even taking insane regulation of fission and the need to process the waste into account. It’s almost like hearing “SSTO Reusable Spaceplanes are the Wave of the Future ™” over and over again, when I know why they can’t work.

Furthermore, where nuclear fission reactors have been scaled to some extent to fit in all sorts of situations (silent power for submarines, the ability to push the navy carriers around in the ocean without a direct oil pipeline back to shore, experimental rocket engines, proposed remote mini-reactors, ect) I’m not sure if a tokomak can scale that easily. You need to hit that reaction/reactor ratio before you can produce power.

If we ever do get fusion power to work, then cool. There are many planets in the solar system that don’t have heavy metals like uranium available in the quantity that they are here on Earth. If we had a tool like that under our belt, we would never run out of fuel in the lifetime of the universe. I just don’t see how, if you’re a city manager with a situation where you have ready access to uranium, you make the decision to build something 10x more complicated and expensive than you have to.

(/digression)
That said, here’s my crazy idea:

These tokomaks are trying to collide light elements together with sufficient energy to cause a fusion reaction. Light elements usually have high proton to neutron ratios, meaning that they have low mass/charge ratios. The nuclei will tend to veer away from each other, unless they are traveling at each other with large velocity and angular precision.

Heavy elements, on the other hand, have much lower proton to neutron ratios. How much easier would it be to collide heavy nuclei in a heavy ion plasma with the intention of fissioning the nuclei than to attempt fusioning light nuclei? Could you sustain a tokomak fissioning a heavy ion plasma where you couldn’t sustain it with a fusioning plasma?

Variation #2:

Current fission reactors use fissile uranium (U-235), however there is something like 100x more U-238 (the stable uranium isotope) in naturally occurring uranium.

Furthermore, thorium, a lighter element, is being looked at because its reactions don’t result in elements heavy enough to be used in nuclear weapons. If you used some sort of reactor based primarily on thorium, you wouldn’t have to worry about proliferation. You could trust this technology to anyone without worrying if they’ll convert it over to producing nuclear weaponry. Thorium also happens to be even more abundant than uranium.

Currently the thorium reactions are being sustained by uranium rods, because the thorium won’t sustain the reaction on it’s own. Not enough neutrons created and absorbed per reaction to keep the thing going.

I’m wondering if it’s possible to sustain a thorium fission reaction by firing a beam of heavy ions through the material. Heavy fast ions collide with thorium nuclei -> nuclear chaos happens -> maybe enough neutrons are generated to trigger enough reactions to make the rod hot? Could you generate enough energy from the reaction to run the particle accelerator sustaining it? If so, you could have a reactor that

1) Could never melt down because it requires active input to sustain the reaction (but not quite as much active input as required to run a fusion reactor) (though modern uranium reactor designs also can claim this feature)
2) can’t be used to make nuclear weapons material
3) might be more economically competitive because it doesn’t need as heavy a containment dome (possibly doesn't need one at all) No danger of internal superheated metal or high pressure steam, if the whole thing can be regulated by the particle accelerator breaking/turning off. No inspectors or guards to keep the materials out of terrorist hands.

I wonder if it could be scaled down enough to use on a car, or in a home? Maybe a nuclear powered aircraft that doesn’t need gasoline and has no range limitations?…

I’d love to see the nuclear revolution re-started after the hysteria of the 70s. I’d love to see this powerful, compact, nearly endless source of energy powering our cities, factories, ships, and spacecraft (you can do a lot with a nuclear rocket engine). The “energy crisis” (we’re running out of oil) or “carbon crisis” (we use too much oil), these hysterical (even longed for by some fanatics) visions of mankind being forced back into a cowed, limited, pre-industrial agrarian zero-sum state (with solar panels) doesn’t make any sense at all with nuclear energy firmly in our grasp. The most maddening thing about it is that it almost was, and that what keeps us from using it isn’t any engineering or technological hurdle, but entirely self-imposed legal limitations!

Is this real?

2007-04-05T19:50:00.000-07:00

http://health.howstuffworks.com/extracellular-matrix.htm

Extra-cellular matrix material triggering regeneration. I wonder, is this just woo-woo nonsense, or real? What is the screening process for howstuffworks.com?

You have to have a deep suspicion about claims for "alternative" anything these days. So much of it is just superstitious credulous nonsense promoted by charlatans and cranks.

But if it's real ... cool. One step forward for medical science.

Eruption on Io

2007-04-04T19:08:00.000-07:00

This shows an eruption on one of Jupiter's moons, Io.

It is cool, isn't it?

Picture shamelessly stolen from http://www.cosmicconservative.com/

Cooking

2007-03-29T05:15:00.000-07:00

I've managed to cook some of my first meals last weekend. It's actually kind of cool really. And it tastes much better than microwave meals. I don't cook every night, for time constraints. But my plan right now is to cook enough on the weekends to last me through some of the meals throughout the week.

The first thing I made was beer and bratwurst. You need 2 beers, an onion, and a package of bratwurst. Put the bratwurst in the pan, chop up the onion and put that in the pan, pour one beer in the pan and turn the heat to medium until the beer and onions cook down to a syrup. Use the other beer with dinner.

The second thing I made was sausage and peppers (surprisingly good for something so simple). Take an onion, one or two peppers (a green and a colored one), chop them up and put them in the pan. Put a can of tomato paste in the pan. Fill it back up with water and put some water in the pan. Put some italian sausage in the pan. (Put a lid over the pan! A little bit of a lesson learned there) Cook that on medium for an hour and a half or so.

And remember, don't make the mistake I did of putting non-stick cookware in the dishwasher!

New Political Blog

2007-03-29T04:58:00.000-07:00

...by your favorite blog author.

I've finally started my own political blog. After 3 or 4 years of contenting myself to lurk and comment on other's websites, I've given in to the urge to bloviate and vent my opinion for all to see.

I've been blogging before this, of course, on http://amssolarempire.blogspot.com, but I've tried to keep that blog low key on the political scale of things. And subjects that do get political, such as energy production, I've tried to back up as much as possible with numbers.

I've done this for a few reasons. One of them is that I was still in college and didn't want to attract attention for political viewpoints.

The other was that I had enough on my plate with engineering school, that I couldn't give my desire to opine on current events full reign. Time constraints prevented it, though the desire manifested as profuse commenting on other's blogs.

A third is that I wanted my other blog to be palatable to people regardless of their politics. There are many people who I respect in terms of their opinion about space travel or science, whose political opinions I find batty. There are people who I agree with on many political issues, who start slinging opinions about science or history, or specific issues that I just stop and find myself on the opposite end of.

So I'll keep up the policy of keeping the two blogs seperate. Those of you who want to enjoy my thoughts on space travel and colonization can still use my old blog, while avoiding wading through my rants. Those who don't mind the fact that I'm a rabid right-winger can peruse both as it suits them.

And I'll welcome any intelligent debate. (Debate by making arguments and submitting information, not by slinging ad-hominems) I know, I know, everyone says this. But I'll try my best to live up to the claim.

The new blog can be found at: http://soapboxzone.blogspot.com/

Google Ate Blogger

2007-02-17T13:27:00.000-08:00

Apparently I need a Google account to continue using blogger. Not too sure what all is involved in this. I don't really like Google, and stopped using them a few years ago because of their involvement in writing the censorship and spy software to police the Chinese internet. Whatever happened to "don't be evil"? That pissed me off, so I'll have to figure out what to do now.

Sight to the Blind!!!!!!

2007-02-17T13:23:00.000-08:00

Let’s give it up for the Doheny Eye Institute, Southern California, and whoever else worked on this project. This sort of thing really lifts my spirits. These people have laid the groundwork for technology that will restore sight to the blind! Particularly people with problems related to the retina, including macular degeneration and retinitis pigmentosa.

They’ve developed an artificial retina implant that sends signals to the retinal nerves. This implant communicates by way of radio receiver to a small camera in a pair of glasses. So far, the resolution is pretty low, but I have confidence that if we can get mega pixels in a digital camera, they can figure out how to improve their system with time and development. They’re conducting medical trials now, for which thousands of people have already volunteered.

It reminds me a bit about the motor cortex reader implant that I read an article about a year ago (don’t have the links…). Apparently another group of researchers managed to read the motor commands sent out by the area of the brain responsible for directing our movement. They could get a monkey to manipulate an artificial arm, or people to manipulate mice on a computer screen.

Imagine how liberating this sort of technology will be for quadriplegics who cannot feel any part of their bodies, to be able to control something! Imagine how liberating it will be for the blind to see again! This sort of technological development is something I love to hear about. These guys deserve our investment and support.

Question about Quantum Computing:

2007-02-01T04:01:00.000-08:00

Okay, so I’ve sort of started to grasp what quantum computing is and how it works (after comments from some of my co-workers the other day). And I hate not understanding certain things – if things are explained to me and I still don’t understand, it bugs me to no end; and I in turn usually bug them to no end with more and more specific questions until I begin getting it at a basic level. I think my internet research to date has given me a preliminary concept though and I’m going to put it up and ask a few questions about it.

(Quantum physics stuff especially bugs me because people try explaining things like uncertainty or Bells inequality with buzzwords “multiple universes” and “superposition of concepts”, like “well sometimes it’s a particle and sometimes it’s a wave”. This doesn’t give me much of a picture of what’s going on, just a series of stories told about the topic. Someday I’m going to wade through an entire QP textbook, nasty field equations and all, just to keep myself sane when the topic comes up.)

Okay, well here is what I’ve gathered about how quantum computing works so far: You start with some data that you want to perform operations on. There is some process whereby several bits of information are encoded in one or more “quibit” vectors. These vectors can be imposed (method unknown) on the state of things like fluorine atoms suspended at extremely low temperatures, ect; where we can preserve quantum superposition of these states. (Quibits being quantum superpositions of on-states and off-states, the superposition can hold the whole vector (with analog probabilities assigned to each vector basis) worth of information, rater than just digital on or off states.)

Okay, so now you have many digital bits worth of information represented by the analog orientation of these quibit vectors. You can now perform other superposition operations between quibit vectors (addition, subtraction, and negation are apparently the limit. conditionals currently require us to collapse the state, reconvert the info, and digitally operate). You are effectively performing operations on all these different pieces of digital info simultaneously by adding the vectors.

Then you reconvert the quibits back into digital information so that you can see what you have. Actually, when you collapse the superposition of states of a quibit you just get either 1 or 0. But when you send the info through multiple times, you get 1 with probability a and 0 with probability b, {a,b} being the components of the resultant quibit vector, which can be re-converted back into digital info using the reverse of your encoding method.

(missing anything so far?)

Okay, so this brings me to some of my questions:

1. Maintaining superposition of states in fluorine atoms is a pain in the butt, requiring cool, yet bulky and expensive lab toys like near-absolute-zero temperatures and big NMRI machines to manipulate and read the state of the atoms. What would prevent you from doing the same operations with analog electric signals? If you have an analog signal a and b, you still have a 2d analog vector in which you can encode some number of digital bits and perform the same addition, subtraction, and negation operations. Furthermore, you don’t have to destroy the info (like you destroy quibits when you read them) to read an analog vector. One pass should give you the straight values of a and b, and thus the resultant vector.

2. QCs are supposed to allow us to solve currently infeasible problems much faster than conventional computers due to our ability to encode some arbitrary amount of information in quibits which can be passed through simultaneously. However, can you do something like matrix inversion without conditionals? Gaussian elimination requires you to look at what you have several times to see what the magnitude of the leading values are in the row are. Other iterative methods of inversion require matrix multiplication. (Can you “multiply” information within a quibit without having to collapse it to read how many times to add another quibit?)

To be continued.

Merry Christmas 2006!

2006-12-25T12:09:00.000-08:00

Merry Christmas! Hopefully everyone is having a wonderful holiday this year. We are, visiting family, making huge vats of egg-nog, giving gifts, ect.

I'm getting a lot of stuff related to setting up an apartment. No more dorm room or microwaved coffee for me. Preparing food is getting more complicated, involving things like plates, metal silverware, sautee pans, and other assorted instruments.

The reason for all this being: I'm done, I've graduated, and I'm off to a new career in the Air Force doing aeronautical engineering!

(It's almost surreal being done with college. Up until two nights ago, I was still having nightmares about final exams! :-P )

Anyway, have a merry Christmas. Good luck classes of December 2006 everywhere. ASBC class of 2006, I'll be seeing you in Alabama shortly.

Shooting Star 12-13-06

2006-12-13T18:43:00.000-08:00

I think I just saw a meteor or something. It went across the sky fast enough, about two seconds before winking out. Pretty neat. I don't look at the sky enough anymore, esp since you can't see squat from school.

Now if it had been just 100 meters wider, it may have even made the news. (Evil laugh).

Doesn't Quite Handle Like an Airplane

2006-12-13T10:40:00.000-08:00

That is my new model Lunar Cargo Lander.

Here you see it hauling a standard EELV cargo can down to the lunar surface.

The rationale behind the lander is that it takes cargo from low lunar orbit to a lunar base on the surface, and vice versa using in situ-derived propellants. (Some lunar in-situ propellant ideas use common lunar materials like powdered aluminum and liquid oxygen. They are easy to produce, but give you cruddy Isp.)

The propellant tanks may be out of realistic scale, I'll have to do the math later.

Launching into the solar system: Celestia Syle!

2006-12-12T19:40:00.000-08:00

Celestia is one awesome piece of free software. It's a planetarium where you can set up all sorts of scenarios, not to mention just view the solar system. If you download the extra high res textures from Celestia Motherlode, Earth and Mars especially begin to look very impressive.

The software allows the placement of spacecraft, basing their appearance off of .3ds files.

Not content to leave the simulated solar-system just glittering there in the simulated sky untouched, I downloaded one of the .3ds editors, Anim8or, off of Celestia Motherlode and have been launching my own "space-program".

The things I find to unwind after exams....

The long range personnel shuttle out for a GEO mission. If you look closely, you can even see some astronauts staring out the window. The belcher among the crew is being cycled out the airlock.

Here you can see my space station. Another of those long range personnel capsules is drifting nearby, along with two experimental engines.

.3ds files and .ssc files will be posted later

Time to blog!

2006-12-10T14:05:00.000-08:00

Well, not quite yet, though I have a lot of things backed up that I'd like to blog about.

First - my econ exam on Tuesday.

But I'm almost out of the hole. Last week was a nightmare in terms of the deadlines and due dates and projects and multiple all-night meetings and......

I'm coming down off a week-long caffiene high coupled with a complete lack of meaninful sleep. But I made it. I'm still intact. I retained my sanity (hee - hee .... hee). Now I need to pull out of school mode and focus on what's next: Commissioning! Graduation! The Air Force! Amazing to think that just one week from now, I'll have a BS in Astronautical Engineering and will be on my way to a real job. Just two days ago, my time horizon was measured in hours till CFD project due, and now it has to expand to encompass the next months of training.

More to come soon.

An Important Point about Freedom of Speech

2006-12-07T07:27:00.000-08:00

An important point about freedom of speech and the internet.
Link:http://denbeste.nu/entries/00000910.shtml

Random Quote 1

2006-11-19T17:41:00.000-08:00

Power corrupts, and the computing power to brute force any integral-differential equation corrupts absolutely. :-P

Except when your teacher won't provide you with the probability function and wants you to solve it in general ... dang.

Schoolwork!!!

2006-11-15T19:39:00.000-08:00

Aaaaagh! If you've wondered where I've been the past few weeks, it's been with my nose to a computer screen out at the Aero building or at home.

I wonder what the minimum posting frequency is before blogger dumps your blog?

Back to the grind. Thank God for coffee! Sometimes it's the only animating force in my body.
26 days or so to graduation!

Misanthropy I

2006-10-20T17:26:00.000-07:00

http://davidszondy.com/ephemeral/2006/10/ozymandias.html

Here's a post, with which I wholeheartedly agree. It appears the misanthropes are at it again, this time of the eco-maniac variety.

I sort of understand this misanthropy, where it comes from. It does not mean I sympathise. In fact, it's annoying, creepy, and indicative of a totalitarian mindset (mankind is not conforming to my beautiful IDEAL, and is therefore evil, hopeless, and worthless, and I will celebrate the day it is brought to its knees).

I've come up against the same attitude again and again. In fact, I'm going to have to invent or find a word to classify these recurrent themes which I encounter repeatedly in the thinking of others.

For example, just today on some random post about fads on an astronomy board, someone posted the following:

"You get blasted with carefully constructed psychological manipulation that promise the next piece of rubbish you buy will finally give meaning to your life. And because most people don't have any meaning in their lives, they are desperate enough to keep falling for it."

Because most people don't have any meaning in their lives. Oh no. Their lives are meaningless. Worthless. Plodding. Monotonous. Why, they go about buying things that amuse them, or please them, or that they think they "need" (a ridiculous notion, since purpose can only be derived from "meaning") without any consideration whatsoever to their grave offense to the observer's aesthetics.

They are desperate, you see? Desperate to find the "meaning" that conforming to the author's IDEAL can only provide. (They just never seem to realize it). Otherwise they would behave "properly", rather than in the intransigent manner that they do.

What condescending dreck!

Perhaps what I'm reacting to is a bit more than what these two examples let on, but I've seen a lot of aspects of this before. From eco-nazis to luddites to apocalyptic prophets of doom, to utopians, this same theme appears again and again. Look at most modern movies and their rank condescention towards the "common man". (Take the Matrix, for example.)

(PS, that's not to say I don't have my moments of depression/pessimism/misanthropy. And it's not to say I think people are perfect or that you can assume their natural goodness. Far from it. It's for things like this that you have to watch your back when dealing with human nature.)

The "sheeple" must be herded to greener pastures, otherwise they'll just stand there, doing whatever pleases them, and we can't have that, can we? It's often taken for granted that they will be herded by "evil" manipulators if they aren't herded by the "enlightened", "good" manipulators, that they have no volition or agency of their own, that their autonomous goals and desires aren't sufficient direction for their lives ("meaningless", "purposeless", "hopeless", "graceless"), or are irrelevant to the Real Important Things.

All I can say is that, when you see this pattern manifesting, reach for your philosophical/political/moral wallet, you're being had.

Biofuels Revisited II

2006-10-13T20:35:00.000-07:00

Ah. Here's the relevant quote from Den Beste. http://denbeste.nu/cd_log_entries/2002/09/Morepracticalproblems.shtml

Biomass: I'm a bit embarrassed that I forgot this one to begin with. Biomass is, at its core, an extremely roundabout form of solar power. The idea is to use farmland to grow greenery, and then to burn the greenery to generate energy, but depending on who is making the proposal the details can vary wildly. Ethanol as a fuel is one example of this, but it is exceedingly inefficient because it is based on corn and only utilizes the grain, and wastes most of the energy in that and uses none of the energy in the rest of the plant.
A more efficient form of biomass is methanol, which can be created from the entire plant. The most efficient form is to burn the entire plant in a big power facility, for instance as a substitute for coal in electrical generation. There are some engineering issues involved, such as the fact that the biomass has to be dried or somehow have its water content reduced substantially, but that's a detail of the process.
It's an attractive idea, but I'm not sure the numbers make sense. I'm not sure I believe it's possible to actually supply a significant portion of our current energy use this way. You're only talking about actually harvesting greenery from the fields once or at most twice per year, and you're only going to get a few tons of dried fuel per acre each time you harvest. The US uses about 60 million short tons (about 55 million metric tonnes) of coal per month, or about 650 million metric tonnes per year.
According to this page at Oak Ridge National Laboratory, anthracite and bituminous coal (which make up most of the coal we use) contain 27-30 gigajoules per metric tonne. Agricultural residues are 10-17 gigajoules per metric tonne (as a function of water content). As an approximation, that means about 2 tonnes of biomass would be needed to replace each tonne of anthracite. Are we actually capable of producing, collecting and transporting 1.3 billion tonnes of dried biomass per year? The US currently has about 200,000 square kilometers of irrigated land; can we generate seven thousand tons of biomass per square kilometer? Or even a tenth of that? Not easily, if it's possible at all.
One of the reasons we can produce that much coal is that it's concentrated; a given coal mine can produce millions of tonnes of coal with a relatively small amount of machinery. But biomass would be extremely spread out, and you'd need an impressive infrastructure investment for all the trucks to collect it and bring it to rail yards for transport to the power plants. And a non-obvious part of the problem is that right now our agricultural practices are using that same biomass, partly to stop soil erosion and partly to reduce fertilizer usage. (Also, a lot of it is used as animal feed.)

Biofuels Revisited

2006-10-13T19:38:00.000-07:00

“Fletcher continues leadership on energy independence”
“USDA and DOE Fund Biomass Research Projects”
“$17.5 million for biofuels”
“Harvesting Sunshine for Biofuels”
“Biodiesel proves its worth with bus fleet (KRTB)”

Some articles from around the internet. Bio-diesel is supposed to save us from fossil fuels. Bio-diesel will grow our way to sustainable energy. It’s the new clean green “way-of-the-future”. The people who aren’t onboard are “oil-lackeys” or “not aware” of fossil fuel’s limitations. They are standing in the way of our bright future. They are the reasons why we’re still dependent on foreign oil. They’re the reason why investors haven’t flocked to the farms. Yeah. Them. Oil lackeys. Bio-diesel is supposed to power our civilization in an eco-friendly way. Will it?

I’ve always been skeptical. Actually, I’ve been derisive. The world burns 50 million barrels of oil per day. The US burns 20 million of those barrels. A barrel of crude oil weighs136kg, so annually we (US) go through about 1 Gtonne of oil per year. 1E12 kg/year. That’s the finish line. If you want to replace the energy we get from fossil fuels, you have to play on that degree of scale. As I’ve pointed out in previous posts that’s a no if’s ands or buts condition. We either generate that level of energy, or we all get a lot poorer and possibly subservient to those nations that manage to hold onto the oil. Civilization is not magically going to morph into some radically “efficient” form where people don’t need to eat, drink clean water, run factories, or ship goods. Can we get here from there growing corn?

Subjectively, when I think of the fields behind my house, the breadbasket of the world, I can’t imagine that something harvested only once a year could possibly add up to that kind of mass. Could a field even fuel the tractor that harvests it? It doesn’t look like it to me.

But let’s run the numbers. According to http://www.ag.ndsu.edu/pubs/plantsci/rowcrops/a834w.htm, North Dakota gets about 121 bushels of corn per acre.

For soybeans, it’s around 40 bushels/acre. That’s industrialized, fertilized, mechanically planted and harvested soybeans. The “organic” (as if industrial agriculture is inorganic!) counterparts to soybeans rate around 16 bushels/acre. http://www.energybulletin.net/1469.html. And that’s from an approving site!

Now, a bushel is an amount by volume measurement. A bushel of soybeans is around 60 lbs. That translates into 1.1 tonnes soybeans/acre. http://www.smallgrains.org/springwh/June03/weights/weights.htm Corn is about 56 lbs/bushel, or 3.04 tonnes/acre. Of course, that’s tonnes of actual corn. The North Dakota site gives around 16 tonnes of silage, and I assume that a fermenting reactor is not particular about which bit it eats.

But you have to alternate corn and soybeans each year, otherwise you wear out your soil. You can’t go overfarming your land without crop rotation, unless you want to set off another dust bowl and ruin our ability to feed the world. So, assuming that you can just go corn/soybean/corn/soybean ad infinitum without consequence, you’d have an average of 8.5 tonnes/acre.

If a tonne of produce could magically be transformed into a tonne of crude oil, then we’d need to farm 117 million acres constantly.

*Note 1 hectare is not, as I have previously assumed, 100 acres. It is actually 2.47 acres. Big difference there. Nice to know when slinging agricultural lingo. :-P

http://www.nationmaster.com says the following about our agricultural statistics:
We have 179,000,000 hectares of permanent arable cropland. We currently grow corn on 28,710,000 of these hectares. Soybeans on a similar area (expectedly). And of course, we’re well to the top of both of these charts, worldwide.

So basically, we would need to devote land on the order of 27% of our arable land to bio-diesel production to make this work, assuming 100% efficiency in food to fuel conversion!!! We’d need to double the portion of our country devoted to corn and soybean production! And, as you all know, assuming 100% efficiency is a good way to be completely divorced from reality.

(Side note – America’s farmland is actually doing far better in the analysis at this point than I initially expected. It just goes to show that you always have to run the numbers when talking about this degree of scale. Humans do not instinctively think in terms of quantities on this degree of scale. We can’t extrapolate from things that we’re familiar with, on our personal visual scale, onto levels of national production, without resorting to a lot of math.)

Next to get an idea of the efficiencies involved, I’ll reference this article that caught my eye – “The Path Forward for Biofuels and Biomaterials”, Science Magazine, 27 Jan 2006. This article talks about harvesting wood for bio-materials. They are looking at something like 10-20 tonnes/hectare for woody crops, about on par with corn. (Though I imagine, far more involved and energy intensive to harvest). I hope they are including a suitable crop-rotation time for the forests to grow back, or we’ll denude our continent for a decade or so of fuel.

They claim that a process involving super-critical steam can break up 57-77% of their bio-mass in their hypothetical bio-refinery into condensable gasses, which can further be processed into syngas (% not given), which can finally be processed into Biofuels.

I think the Fischer-Tropsch process is commonly mentioned as a last-step in the creation of biofuels. Fischer-Tropsch can also process coal and other materials into fuel. For this DOE paper (http://www.fischer-tropsch.org/DOE/DOE_reports/NREL/TP-431-8143/TP-431-8143-1_sec1.pdf) it seems as if the maximum theoretical stochiometric efficiency of coversion is around 39.3%.

Stochiometric efficiency isn’t by mass efficiency. It looks like they’re measuring mols hydrogen per mol biomass. CH1.47O0.67. Looks like it would relate to a hydrocarbon CnH2n with something like a 40% or 30% by mass ratio.

So the overall process is looking like it’s around 25 – 30% efficient by mass. For brevity (and due to time constraints), I won’t consider harvesting, transporting, or the energy costs of refinement. We will need around 400 million acres of farmland to replace our gasoline consumption. We would need to be using something like 90% of those 179 million arable hectares for biodiesel production.

I don’t think we’ll be able to replace gasoline with bio-diesel. I’ll admit that I didn’t imagine it would even end up in the neighborhood, but it seems our nations maximum possible agricultural production is at least in the neighborhood with what it would take to produce sufficient quantities of biofuel to free us from fossil fuels.

Still, it doesn’t need to be pointed out that we don’t need to nuke our soil with incessant corn production. Nor can we cease our agriculture for our other purposes. We need food. We need corn syrup for almost every industrial process imaginable relating to organic substances. The rest of the world needs our food too. We can’t be giving 90% of that up to get rid of oil.

You might protest that we’ll only need some fraction of our oil replaced by biofuels. 10-20% replacement is a good start. But the problem is, that's where it will stop too. What happened to “energy of the future?”. So we’ll be needing 80-90% of that oil after all? The goalposts have moved then. This won't be making us "energy independent" by any stretch of the imagination. And we’ll have to give up 10-25% of our farmland to achieve this? (And, assuming the economics of the situation don’t change, we’ll have to be subsidizing it at that!) Doesn’t sound like much of a deal to me. To pretend that it will replace oil feels too much like an agricultural scam.

If you want to replace oil, I mean actually replace the energy behind it, you’ll have to turn to a different source. But at least, after examining the concept, I won’t laugh as hard as I was laughing. At least it isn't windmills.

Steven Den Beste at USS Clueless blog (now, unfortunatel, inactive) has written several posts on alternative energy, mostly him raising similar objections to the ones I have raised, but with far more eloquence. http://denbeste.nu/cd_log_entries/2004/07/Justdoit.shtml. Somewhere in one of his three articles I thought I saw something on bio-diesel. Not sure though. And, though he thinks large-scale nuclear power production is an insurmountable marketing obstacle in the short term, I believe, as stated in my previous posts on energy, that the prospect of going back to the 17th century in the long term (100 years or so) is a highly persuasive marketing force.

Verne's Cannon Part I

2006-09-23T19:41:00.000-07:00

I've been thinking that I've been a bit too much of a wet blanket lately on various subjects. I've tried to define things that I've felt were unfeasable, or unworkable, or didn't make any sense. Esp with my recent posts on energy (since I feel both that many highly touted alternatives simply will not scale, as well as that it's important to provide this energy somehow).

But anyway, enough with what can't be done. Now I'm going to get downright whimsical.

I've read threads on the space elevator recently. If we ever manage to get a material that has a high enough tensile strength versus density, we may yet be able to build the thing. However, nanotubes are still problematic, seeing as how they slide against one another. The macroscopic material may not end up with the strength of the individual fibers. (There I go again)

So, I was thinking about other non-rocket methods of launching into LEO. One of the ones that has intrigued me for a while is a launch catapult.

The launch catapult idea has been looked at by NASA as part of it’s 90’s X-plane efforts. In their formulation, the catapult will accelerate a rocket up to a few hundred miles per hour so that it can start a scramjet. However, it’s not intended to provide any meaningful contribution towards the total deltav required to get into orbit. The envisioned space-plane will still have to provide almost all of it’s own dv, which means it will still have to carry substantial amounts of fuel (and be aerodynamic besides, seeing as how it has to operate in the atmosphere for extended periods of time to get any advantage from it’s scramjets).

However, I was interested in a mostly non-rocket launch method. What if we could get almost all of the dv needed to make orbit from the catapult? Maybe a circularization burn once the spacecraft clears the atmosphere, but have the spacecraft fire off the catapult at 8000m/sec or so, blast through the atmosphere, and off into orbit?

This would basically be a re-creation of Jules Verne’s cannon. The system I envision is more like a 1000km long mag-lev acceleration track. (1000 km comes from the requirement to achieve this exit velocity while limiting the acceleration of the spacecraft to <5 g-forces. Shorter tracks can be made for unmanned rockets). I concatenated a lot of my older simulation code together into a simulation of a spacecraft ascending through the atmosphere, using Earth’s standard atmosphere model, under such conditions. In the simulation, I had the track firing the spacecraft off at a 0.5 degree angle with the ground. Assuming a light drag coefficient (around 0.05), my 200 ton simulated vehicle made it’s way to 25km altitude in less than 40 seconds (basically in a straight line). This is where my standard atmosphere model quits, so I assumed zero atmosphere afterwards, though this isn’t really the case. (a point of refinement for later models) Even though the drag forces are huge, they apply only for a very limited time. Dynamic pressure can become problematic.

At this velocity, dynamic pressure is around 400 atmospheres (what a submarine would be experiencing at a 4km depth.) You might think this would sink the whole project. 400 atmospheres is a bit much to withstand for an aerospace vehicle. Furthermore, you’ll also have supersonic stagnation, and supersonic temperature for the few seconds you’re within the lower atmosphere. A normal plane or rocket would be crushed like a can.

However, the mass limits for the launched vehicle aren’t determined by any normal aerospace consideration, but rather by the capabilities of the launching system. If you’ve already invested enough to build some 1000km long launch track, you’re probably going to want to beef it up as much as possible. Furthermore, a more massive vehicle is an advantage, since it helps the vehicle punch through the atmosphere. So why not build it like a submarine? Better yet, encapsulate the rocket in a steel pressure-vessel hull designed to blow off after the vehicle has exited the atmosphere. (freeing the payload to circularize into a stable orbit, and jettisoning the shield mass). The shell can ablate in blazing glory upon ascent and bomb out in the ocean. While you might think this is a waste of good steel, steel is cheap and plentiful. Remember, material costs are a minor fraction of the cost of a vehicle, and machining steel is absurdly cheap and well understood compared to most high-performance aerospace processes. We could easily mass produce all the ascent shells we would ever need as part of a major space effort.

This whole approach is surprisingly workable, assuming you’re willing to build such a piece of infrastructure. Obviously this won’t be cheap or easy. It would have to be built across several states, (or, while I’m in this whimsical frame of mind, out in the ocean, between several platforms). It would only be justified if we really wanted to put mass into space on a daily basis, as part of a colonization effort or something. Other negative side effects include a car overturning mach 25 sonic boom at the exit. Still, this could be made to work (to my knowledge) with current material technology, and a boatload of powerful track magnets. If the space elevator doesn’t work out, this could end up being another railroad into space.

Spacecraft are NOT Airplanes I

2006-09-01T10:53:00.000-07:00

A fellow space-geek discusses the new CEV, and gives some very good commentary on the significant advantages of capsules over "space-planes", which exist in the public mind in that annoying, fixed, way-things-are-going-to-be-to-the-exclusion-of-every-other-possibility type mindset. I agree, and have commented about this before on various forums that there is only 1% of a spacecraft's mission profile where wings are anything but a hobbling disadvantage.

His podcast is here:
http://geekcounterpoint.net/audio/GC002_NASAGoneHollywood.mp3

Energy: So you want to replace oil?

2006-08-26T17:24:00.000-07:00

This is a very very long rant about energy, and my attempt to provide my perspective on the issue. Energy really is of central importance to our society, and entrusting our energy futures to pie-in-the-sky dreams, conspiracy theories, witchhunts and political pandering is not in our best interests. Getting a good perspective on this issue is a task requiring some analysis of the actual degree of scale that we're talking about, thermodynamics, and the actual efficacy of different methods of power production. If the public became better informed (I mean really informed, not just subscribing to the latest "alternative" energy fad), it would then force politicians to stop playing public-perception games and obstructing the development of sound enegy sources.

Energy: What You’re Up Against When You Talk About Getting Rid of Oil
So, you want to free America from its “oil dependence”? You think conservation, or fuel efficiency is the key to becoming self sufficient? After all, we’re “dependent on energy”, and we really shouldn’t consume so much, right? Idealized, primitive (thouroughly oppressed) peasants in their rice paddies don’t consume anywhere near the energy that we do. But then again, primitive peasants don’t produce most of the world’s wealth, or enjoy much of it, do they? The modern industrialized lifestyle exists because we have found ways of getting machines to do our work for us. Machines don’t do work for us when they don’t have an energy source. Per capita wealth is directly proportional to per capita productivity. Per capita productivity is proportional to the amount of machines we have working for us, the extent to which they work for us, hence the amount of per capita power we have available. If we were to suddenly stop consuming energy one day, then that would be it for civilization as we know it: Back to scratching the dirt with a stick hoping to glean enough off of the land using primitive farming techniques to feed yourself (or enslaving your neighbors to do so, which is probably more likely). No fertilizers, backhoes, or even pumped irrigation, and you can forget about transporting produce long distance. A life without energy is a life of medieval grinding poverty (and serfdom to those who still have the use of energy and industry).

So no, civilization should not free itself from its “energy dependence”!! Civilization is dependent on energy exactly as much as the body is dependent on oxygen. Without it, there is no hope of using our resources or doing work to anywhere near the extent that we can do today.

1. Efficiency

So, one canard down, what about “efficiency?”. Surely there are ways we can improve the efficiency of our processes so that we don’t need to consume energy at the rate that we do? There is room for improvement in efficiency to a limited extent. But it also depends on what sort of efficiency you’re after. Do you want efficiency, as in consumes less energy (usually what is meant)? Do you want ease of manufacture? Do you want the product to be efficient to design and maintain? These different sorts of efficiencies are often in conflict. Economic efficiency means providing you the product at the least cost and overall effort. Energy efficiency often requires more complicated, difficult to manufacture devices. Furthermore, efficiency is a sharp diminishing return game. It’s impossible to be more than 100% efficient. It’s thermodynamically impossible to be more efficient than the devices Carnot efficiency. For diesel engines, we’re at about 34-40. For large power stations, we’re at 40-60%. (Cengel, Bois, Thermodynamics, 254). As you approach these barriers, the convolution and cost of your device approaches infinity. The ideal efficiency, the ceiling at which you thermodynamically cannot operate above, no matter how convoluted your diesel engine gets, is between 60-70%. (Cengel, 464, a function of the compression ratio btw).

Theoretically, assuming we could pack a device that somehow managed this 60% efficiency in a truck, which could then get this efficiency under real world conditions, we would be able to reduce our oil consumption from 7.3 billion barrels a year to something like 5.8 billion (we use something like 70% of our oil for automotive purposes. We use the rest for heating and electricity production). That could save us some time, as far as total oil supplies go, but it extends our oil-driven lifespan (whatever it turns out to be) by only 25%. That is the most we can expect out of increasing our efficiency. It’s not going to free us from foreign oil. The only thing that will free us from foreign oil dependence is actually developing our domestic oil supplies.

2. Notes on how much oil is left:

The world consumes oil at somewhere around 50 million barrels/day. There are 836 billion barrels estimated in our proven reserves. (Source: http://www.infoplease.com/ipa/A0922041.html)
Proven reserves mean conventionally extractable, readily refinable oil (of the right characteristics) that has been discovered and mapped out. It doesn’t mean that that is how much total oil there is. There are unconventional oil deposits (such as shale oil) which require unconventional extraction methods (which are currently being developed by our oil industry). http://www.radford.edu/~wkovarik/oil/ These reserves can be as high as 2 trillion barrels not counting the Venezualan Orinoco heavy oil belt (which may contain an addition 1-4 trillion barrels). So, proven reserves are going to run out in 50 years at present consumption rates, assuming both a continuation of present consumption levels (unlikely – they’re probably going to increase exponentially as they have throughout history) and assuming that no new proven reserves will be discovered (also very unlikely – the ocean coasts are probably lousy with unexplored oil as the recent events in the gulf and Alaska demonstrate). We could have anywhere from 50-200+ years of oil left, depending on the playout of many unforeseeable factors.

Nevertheless, it is going to run out someday. Furthermore, the use of all conventional oil supplies is likely to cause some significant discomfort. Shale oil, and other harder to mine deposits, though present in larger quantities, are also more difficult and expensive to mine. Another note – eventually the process of extracting the oil takes more energy than you would get out of the finished gasoline. Contrary to popular belief, this isn’t an impassible barrier by any means. You just need to use a non-oil energy source to drive the extraction process. (My favorite, for reasons I’ll go into in future posts, is nuclear).

So rather than running dry instantly, the following scenario is likely to play out. Assuming 100% social flexibility (ie. The government will let the oil companies do what needs to be done to get at these deposits, which, given the popular mindset of environmental self-flagellation is far from given), oil companies will attempt to mine ever more difficult deposits of oil. The easiest ones to get at (and hence the cheapest) will obviously go first. After that, harder and harder deposits will be mined. (These more difficult deposits, fortunately exist in larger quantity). Gasoline will continue to get more and more expensive, as harder deposits are mined. Eventually the gradually increasing prices will drive us to a different energy source. We’ll never run out of oil, we’ll just have to stop using it as our primary energy source at some point.

3. We need a SOURCE

We need an energy source. This one central fact of civilization will not go away as long as civilization exists. You have an enormous stake in making sure it continues to exist. We cannot loftily abstain. We cannot make ourselves more and more efficient until we cease to require sustenance. I’m certainly not going to tolerate a sub-industrial lifestyle, no matter what you may prefer, and I’m willing to fight for it, so you can count out placating people like me into passive sacrifice.

An energy source is distinct from an energy transport or storage mechanism. Hydrogen will not power our civilization. It may power our cars, but it is not a source. It is a proposed storage method. Hydrogen doesn’t sit around in pools in the ground like oil does, in a naturally elevated chemical energy state. We have to produce it, and to do so, we have to expend energy. Another example of a transport mechanism, as opposed to a source, is a battery. It is charged with energy generated elsewhere.

We’re making progress on our storage methods all the time. Our batteries are at about 15% the energy density of gasoline by mass. http://hypertextbook.com/facts/2003/ArthurGolnik.shtml. I don’t have the source, but I was reading something the other day about a boron-hydride fuel cell that uses boron hydrides (far easier to work with than LH2 or compressed hydrogen btw) to get 1/5 the energy density of gasoline within the fuel cell unit.

But what is going to drive this process? We’re talking about replacing 7.3 billion barrels of oil/year. That’s 6.1E9 J/barrel (http://www.eppo.go.th/ref/UNIT-OIL.html). That’s 1.4E12W of energy. That’s assuming there aren’t any inefficiencies in converting the driving energy into these equivalent fuels. 1400 GW. 1,400,000 MW. 1000 Hoover Dams!!

Energy: Part 2: Energy Sources for Civilization

2006-08-26T17:04:00.000-07:00

3a. Solar

Personally, I don’t think solar power will cut it. The primary reason why is that solar power isn’t being proposed politically for the purposes of providing actual electricity. It’s being proposed as a magician’s distraction to seize our attention while nothing is done to actually de-regulate energy production. A sop to placate us. Perhaps a plant or two will be constructed, as pet projects for senators and contract seeking eco-firms.

The second reason why is that solar energy is very very diffuse. It is not “free energy”. It requires refined silicon panels, which are expensive to make. It requires batteries to store this energy during night, transformers to step it all up to usable voltages. Per square meter, there is just not that much of it. I have heard over and over again “If we just pave our roofs with solar panels, we can meet our needs”. Will this cut it? Let’s see. At Earth’s distance from the sun, it receives about 1370 W/m^2 in terms of energy. Only about half of this energy makes it through the atmosphere. And the sun is only in the air half the time. So you’re only getting about 340 W/m^2 on average.

If we assumed 100% efficiency of our panels, our storage process, transmission, and our conversion of that energy into chemical energy, we would only need about 4100 km^2 of collection area to do the job. But assuming 100% efficiency is a good way to be totally divorced from reality.

There are two main types of photovoltaics out there: silicon and gallium arsenide. Gallium arsenide solar cells are about 37% efficient on satellites, and 26% efficiency has been achieved terrestrially. Link However, we can’t make miles and miles of panels out of Gallium Arsenide. We’d have to go with the silicon panels.

Silicon solar panels are about 12% efficient at room temperature (at colder temperatures, the cells are more efficient. However, considering that the cells get their energy from sitting in the hot sun, this is somewhat self-defeating). Link

I don’t have any solid sources, but charging and discharging battery banks is likely to be about 30% efficient. We need the battery banks to store energy for cloudy days, or for periods when the efficiency falls below optimal, or when usage peaks. Since solar power doesn’t output at a nice predictable rate, these are required to smooth out the transition.

If we then, finally, assume a generous 50% for the efficiency of producing and transporting the artificial fuel, we’ll end up needing something like 230000 km^2 (87,000 mi^2) of solar panels. (a square 480 km (300 mi) on a side).

That doesn’t sound too much like free energy to me. Don’t even get me started on the fact that these solar panels have to come from somewhere (refining silicon from sand, ect) and that they have to last sufficiently long to return the amount of energy it takes to produce them in the first place.

Solar might be an option for powering small appliances and lighting, or road-signs. It might even provide remote power for camping. But it’s not going to replace gasoline.

3b. Bio-diesel

This is sort of like the organic version of solar power. Plants are basically solar powered organisms. They store their energy in sugars and other substances that we can refine into various hydrocarbon fuels. They are one step over solar in one regard – we don’t have to expend the same energy refining silicon. Plants are self-constructing.

However, we do have to till the soil, provide irrigation, ect. Furthermore, these plants are going to be in direct competition for our most arable land, which we need to feed the world. At least, if we continue to want to be the bread-basket of the world. We do have plenty of arable land available, however, so let’s assume that the same people who dream of bio-diesel powered cars will also give their parklands, wilderness, and forests over to bio-diesel farmers.

However, you need to gain sufficient energy from the refined fuel to afford harvesting it. Remember, this is supposed to be our primary source, you can’t pass the energy debt off to something else. Also, plants are much much less efficient, from an energy collection perspective than photovoltaics. So the amount of farmland necessary to implement this is likely to be vast. (At this point, I’m running out of time, so my discussions are going to be a little less quantitative).

3c. Windmills

How fast do alternative energy buffs intend to wave their hands?

3d. Tidal Generators (I like this one)

Tidal generators actually have potential for use as a primary source. The tides are predictable, consistent, and, most importantly, they pack a punch. Thousands of tons of water moving back and forth on a day to day basis can be made to move back and forth through our turbines into artificial reseviours, providing significant power. They, like hydroelectric power, require pouring a lot of concrete in some highly inconvenient areas, however. It would require a significant re-arrangement of some coastal property, most of which is densely populated, to make this work.

3e. Enviro-Luddites in Hamster Wheels

Egads! I’ve got it! Race you to the patent office! Promising, very promising, but it would require them adopting a somewhat more substantial diet than tofu and organically produced vegetables. And then it would devolve into another version of bio-diesel.

3f. Coal Power

I’m rather unsentimental about the environment. My main concern about energy is from a human perspective. You’d have to be pretty darn convincing to get me to believe that any old industrial eyesore or the death of the purple-spotted-worm is too much to ask of the environment if it benefits mankind. But even I would be opposed to coal power on environmental grounds. There was a point in time when London was choking on suffocating yellow fog due to their prodigious burning of coal and local weather characteristics. Coal power produces pollution. Real pollution. Particulates, sulfur, smog, all in non-trace quantities - not just the CO2 you get from burning oil.

The recovery of our environment from the industrial revolution began, believe it or not, when we converted from steam engines, wood furnaces, animal power and coal boilers to oil internal-combustion driven processes. Far from being a despoiler of the earth, the IC engine saved us from what was, at the time, the only other alternative.

Furthermore, how fast and recklessly do you want to mine this stuff? Can it be longwalled at the rate it would take to supply 1.4 terrawatts of power? At such a frantic pace, it’s likely that miners would be routinely dying in mine collapses. The other alternative is to strip-mine it, which means removing hill-sides, scraping it all out, and tossing the dirt back on top.

What on earth are we going to do with all that sulfur? Better figure out a way of making solar panels out of it, and fast. Otherwise your water will end up tasting pretty funny.

3g. Am I going to say it? … The word … the awful, evil, violent, hideous concept which will kill us all? Yes.
NUCLEAR POWER (my favorite, obviously)

Capital letters are appropriate. Nuclear power has the most to offer us, IMO, out of all our energy sources to date. It is the most powerful (by several orders of magnitude) compact force that mankind has managed to tame. It’s ironic that the most publicly hated and feared means of generating electricity is the one that came closest to fulfilling all reasonable demands of environmentalists, industrialists, consumers and people who want nice open-spaces (as opposed to flatlands paved with photovoltaics). Some people, however, in the absence of being able to find reasonable objections to something they oppose, will begin to fling unreasonable objections with desperate fervor.

To hear opponents talk, a nuclear reactor is such a dangerous and unstable device that it’s ready to explode at any moment in a furious mushroom cloud. That the waste products (spent fuel rods – the same size and almost the same mass as the ones that went in in prior years) constitute some mortal danger to the public. Nothing could be further from the truth!

Nuclear waste is no more or less voluminous or massive than the rods which went into the reactor in the first place (not counting sections of de-commissioned reactors, which also have to be cut up and stored). And one nuclear fuel rod will go a very very veeeery long way. We have 103 nuclear power plants. These power plants provide 20% of our nations electricity, however. And in their years of operation, we have only produced around 50,000 tons of waste. That sounds like a lot, but compare it to billions of barrels of oil every year. Compare it to the hundreds of millions of tons of other products passing around our society every year. This waste takes the form of solid metal objects. The current storage method is to put these materials into dry-casks designed to keep the waste sealed and dry for millennia. Unfortunately, we’re currently storing these casks at the reactors themselves, or in temporary storage throughout the country, since no one wants a permanent disposal site built anywhere.

We could easily store this volume of waste in a single large storage site, like the ohio salt domes, for instance, or any other geologically stable region. Currently, our country is trying to obtain permission to bury it in a fortified hole in the side of a mountain in the middle of the desert, and even this meets resistance.

Supposedly, nuclear waste has to be stored for millions and millions and millions of years, forever. This crazed requirement is yet another unreasonable obstacle that is thrown in the way of nuclear power companies. While the radioactivity of the spent rods does persist, the output exponentially decays over time. Eventually, you’re left with the basic radiation that was present in the original uranium. It’s dangerous to be near the waste while it is unshielded and fully concentrated, but while it is underground in water-sheilded containers? Our current regulatory standards are to construct a device that can store the waste against corrosion and water for 10,000 years.

Still, people worry that some-day, in the far far unimaginable future, water will eat through the walls of the armored container and all hell will break loose. In reality, since the containers are likely to be stored in a dry environment, you’ll have to wonder if it will leach away into the water through the armored storage container at a rate appreciable enough to build up noticeable concentrations in anything, much less migrate into used ground-water reseviors. It’s almost as if the waste is to be imbued with some malevolent intent to poison us. We’re talking about solid, chemically inert metal rods, not malevolent entities out to destroy the world.

They also worry that our distant descendants (presumably too stupid to understand what nuclear waste is, or to avoid the dangers associated with breaking into our waste-storage facilities) will dig it up and eat it, or something, and must be warned of their impending doom. Hence ridiculous measures to post enduring warnings and hieroglyphics (see national geographic). I fully anticipate our descendants will break into our nuclear waste storage facilities. They’ll want the waste, because it actually isn’t “spent” by any but our present irrational standards. In fact, we’ve used less than 1% of the energy we could presumably wring out of the uranium in the rods. There are reactor cycles that can re-process that “waste” over and over and over again into newer generations of nuclear fuel by using a “breeder reactor” to breed plutonium and more U-235 from the inert U-238. (the non-fissioning uranium that composes most of the metal, it is only the U-235 that fissions). This process could extend the available enriched uranium from a centuries long supply to one that could last us millions of years (effectively forever).

Nuclear sources:
eia.doe.gov Article
www.eurekalert.org Article
http://www.uic.com.au/wast.htm
Link
Link
National Geographic Article

(Aside: Geez. I’m having a hard time finding numerical references. Try typing “Nuclear Waste” into a search engine to see just how wild-eyed the paranoia over this waste is. You’d think it was nerve gas or something. A poll popped up – apparently the vast majority of people believe that the US has the most nuclear waste per capita, which is totally nonsensical, seeing as how we are far from the world leaders in per-capita nuclear energy use!! This is an important insight into emotional thinking. Nuclear waste isn’t an actual product of an actual physical process to most people. Most people think of it as merely another indicator of eeeeevil. And “everyone knows” we’re the biggest selfish polluters on the planet.)

Other benefits of nuclear power are that it has a very small footprint on the world (unlike solar, wind, or bio-diesel, a nuclear plant doesn’t require thousands of square miles of coverage to do its job), it emits no carbon dioxide, it actually emits less radiation than coal plants (which actually spew trace uranium into the air with their particulates). In fact, unless your containment dome (a large concrete bunker over the reactor designed for preventing even a catastrophic internal explosion (larger than anything a reactor is capable of producing, from a nuclear professor I know) from allowing exposure to the air) is broken open somehow, they emit nothing at all.

When evaluated on its merits, nuclear power is a dream come true. I think it will become our primary energy source, no ifs, ands, or buts. Hydro-power and tidal power will also continue to provide industrial scales of energy. Wind and solar power will provide non-automotive residential energy at best. If we want to replace gasoline, I mean really want to do it, as opposed to merely sneering at gas-guzzlers and feeling good because we care, then your only real options are nuclear and hydro.

Energy: Part 3: End Notes

2006-08-26T17:03:00.000-07:00

Other Misc Notes

(notes – we consume 73 billion barrels/year of oil. Our vehicles use 167.75 billion gallons of gasoline/day. There are 234,624,000 of them as of 2002. There are only 407,000 alternative fueled vehicles as of yet, and most of them derive from natural gas, which is a much rarer fossil fuel than oil.)
Source: http://www.infoplease.com/ipa/A0004727.html

Link

Link
7.3 barrels/tonne crude oil
18,300 Btu/lb

5.8E6 Btu/barrel gross
1055.0559 J/Btu
6.1E9 J/barrel

Hoover Dam – 1434 MW output.

This guy thinks the most we can expect from solar is 77MW/km^2.
Link

Earth’s radiation budget
Link
1370 W/m^2. About half makes it to Earth. Earth is lighted about half of the time. So you get 340W/m^2 on average.

Link
This source gives a different energy budget, taking into account clouds, ect.
He has it varying between 342 and -100W/m^2 seasonally. This is net radiation though, so it takes nighttime and Earths outbound radiation into account.

Link
This site gives some information on photovoltaic conversion.

Link
More photovoltaics info.

Requesting Advice 1

2006-08-23T17:04:00.000-07:00

This semester, I'm involved in a team-class-project to solve an engineering problem. This happens a lot throughout my education, for obvious reasons. And once again the professors are distributing the usual teamwork-is-awesome stuff. Some of it pretty good this time around. However, in my experience with teamwork so far, there have been some disasters, and I was wondering how I might help steer the group clear of them, avoid causing them myself, and contribute more effectively.

My question is this: Are there any teamwork strategies that have worked extremely well from your experience, over others? Are there any failure modes that commonly happen that turn your team into a disaster?
If you were in the leader's position, how would you ensure that everyone had what information they needed? Keep meetings on task?
If you were in a follower position watching one of these failure modes occur, how do you counter it?
Do waterfall diagrams signify anything corresponding to the project? /sarcasm

I'm a Nanotechnology Skeptic

2006-08-19T05:57:00.000-07:00

I’m a nanotechnology skeptic. It seems like nanotechnology, as I understand it, and nanotechnology, as the popular futurist conception of it is, are two different things. You might be wondering at this point “What kind of futurist are you anyways? Nanotechnology rules. It can do anything”, which is sort of my point.

People seem to think nanotechnology can do anything. In fact, it seems they want it to be able to do anything. It seems to me almost as if people are reasoning backwards, from a desired outcome to a predetermined thing-that-should-make-it-possible. Nanotechnology is treated as a magical substance, instantly and effortlessly manipulating the world to exactly our specifications. Causing whatever we desire to appear on a whim. Turning material considerations into mere abstractions that won’t require any human attention, ushering in a classless society, and abolishing war (that should be your first clue that the desired outcome is searching for a cause, rather than vice versa) It’s also supposed to be unstoppable grey goo that could eat our entire planet with microscopic self-replicating constructors.

But when you look at things from the perspectives of the challenges facing us in even developing microscopic mechanisms, a lot of these scenarios don’t make sense.

The easiest one to debunk is the runaway replicator “grey-goo” scenario. Seeing as how we haven’t even built macroscopic von Neumann constructors (devices which are capable of producing themselves under automated control) (though by no means is this unreasonable, for a macroscopic device) that microscopic von Neumann constructors are just around the corner.

First of all, lets define how these replicators are supposed to assemble:
1) What materials are they going to assemble from? If they are going to assemble from pre-made parts, then it’s impossible for them to run wild in an environment that isn’t saturated in these pre-made parts. If, on the other hand, they are constructed from raw materials, the replicators would have to contain microscopic factories to fabricate these parts from raw materials. (Which drastically increases size and complexity – you do want these things to be microscopic, right?).

((An important caveat – I’ll get to this more at the end of the article – Life is composed of “nanotechnology” of sorts. Life has managed to solve nearly all the problems of operating at microscopic degrees of scale. It also comes with its own limitations and considerable advantages. But that’s not the popular conception of nanotechnology. The popular conception of nanotechnology is, essentially, precisely designed machines after the manner of our macroscopic devices, operating in a similar manner, using similar methods . . . just tinier. My main objections deal with this conception of nanotechnology))

a) These factories need some sort of control mechanism. If this control mechanism is an electronic computer, then these “nano-devices” aren’t going to end up being very nano in scale. Electronic computers are necessarily macroscopic devices. You need a certain minimum size for transistors to work (around 50nm/transistor), for heat to adequately dissipate, for electromagnetic interference of one switch to be minimized at the next one over, ect.
b) There are, of course, other types of control mechanisms, but these are severely limited with respect to the directness of our control. One such example is the chemical “computer” of our DNA. If our nanotechnology devices are controlled by such means, then it means that we won’t be able to give each device real-time marching orders. The best we could do is give behavioral pattern type instructions and turn them loose to do their thing.
c) Are these devices going to assemble from metals? If so, your replicators can’t run wild, seeing as how they would need a metal rich environment in which to draw their materials from.
----i) How are you going to get the energy to work metals anyhow?
d) The only real option for runaway replicators is for them to be assembled from ubiquitous materials such as carbon, hydrogen, oxygen, nitrogen. The same materials that life in general assembles from. But this brings up a host of issues, not the least of which is that you’re not making tiny little machine tools and lathes out of sugars, amino acids, and other molecules that would rather dissolve in water!

2) Where will these runaway replicators get the energy to run-away? It follows that for this grey goo to be able to eat the world, it has to have an independent energy source. If it gets its food from operating in a fuel medium, then it can’t run away.
a) If they get their food from eating other organisms and burning their molecules, then the replicators have to be able to get a sufficient energy return on their investment. That means that they not only have to be more efficient than life at doing what they do, they also can only attack and survive in organisms with a sufficient density of consumable molecules. They can’t expand and eat just anything. They would be, at worst, opportunistic parasites.
b) If they use solar power to replicate, then they can get independent power. But the power available to your grey-goo is not going to be sufficient for it to chase people around the block and eat city blocks within half an hour. In fact, it would be downright slow – no faster than your average moss growing on a pond, assuming they are even as efficient in self-replication.

3) This just segues into the next point: Will these devices be able to out-compete life? Will it be the nano-devices that end up snacking on people, pavement, plants and other life, or will bacteria and viruses be the ones eating your nano-devices for lunch? They are made from similar materials, but life has a serious advantage over designed nanotechnology: It is supremely adapted for operating on its degree of scale. Billions of years of ruthless competition have resolved the microscopic world of life into self-replicating surviving, eating, breathing, metabolizing, photosynthesizing machines of extreme complexity, unsaddled by human preconceived notions of what replicators should operate like. Would we be capable of designing anything to beat that so easily? I think not.

So now on to mechanical nanotechnology in general: By now, if you’ve given it some thought, you can probably see how little tiny robotic arms are going to be a bit problematic on the nanotechnological degree of scale. For one thing, it’s hard to get anything to be rigid if it’s only a few thousand atoms across. Temperature introduces noise at that degree of scale. Furthermore, chemical electromagnetic forces come into play that make operating a little tricky. If your robotic arm grabs a large macromolecule, the molecule might not decide to come off! It might electrostatically bind to the end of the arm. If it chemically reacts with your arm, it’s likely to release so much energy (for the degree-of-scale that we’re talking about here) that it fries your device, as well as putting extreme loads on the arm. Grabbing molecules with “little tiny robotic arms TM, would be like handling glue-coated land-mines with blunt jello baseball bats. Corrosion would be deadly to a nanodevice. A reaction with a stray oxygen molecule in the wrong place could eat through a critical mechanism (and fry the device through energy release). (The best defense against grey-goo is likely to be a lysol wipe. )

So, as you can see, producing mechanical nano-devices is simple. It’s just a matter of making a really really tiny self-replicating robot, and you’ll be ordering mountains of matter around on the molecular level (effortlessly, btw), and blackmailing the world with planet eating grey-goo in no time. /sarcasm.

Mechanical nanotechnology could probably be made to do some important work, such as ordering molecules around on a microchip, constructing microscopic sensors, threading the wiring for other very small devices. What it is not likely to be is effortless or cheap, since it is not likely to have the capability to easily self replicate. You might be able to get your nano-metallic-print head for a layered-substrate type of device, but it will probably set you back some, since it is likely to be a very tricky thing to construct.

Biological nanotechnology:

I’m not a complete curmudgeon when it comes to nanotechnology replicators however. I do think that there is one type of nanotechnology replicator that might work some real wonders if we keep at it. Rather than re-inventing the automobile starting in the stone age, let’s hijack some of the wild ones running around in the open plains, so to speak. You’ll probably get more mileage by ordering bacteria around, giving bacteria the genetic instructions on what you want them to do, rather than attempting to build the things from scratch with tweezers and a microscope.

This offers some advantages – the nanotechnology, once told what to do, will be able to self-organize into structures of extraordinary complexity.

One advanced example might be neural interface. You could try doing neural interface the old fashioned way by going in with tweezers, and attaching metal electrodes, but this is a rather blunt way to do things. For one things, your neurosurgeon would have to have very steady hands and an extreme amount of patience (1 retinal connection down, 100 billion to go ….) These connections are also likely to produce allergic reactions, or kill the nerve cells they’re next to. If you could produce the connection by having micro-organisms go in under the orders to interface with the neurons and create neuron chains back up to the surface, then expand their resolution out to something that a mechanical device can handle, you could create the biological equivalent of an interface port. Furthermore, inside your skull, these microorganisms could be equipped with all your surface markers, so that your immune system doesn’t reject the interface. I really don’t see too many other ways to get the sort of intimate mind-machine interface depicted in the Matrix than to do it under the fine and autonomous control of biology.

Another example might be the improvement of your immune system. If you can create some mean-lean-fighting bacteria with an improved understanding of what constitutes an invader to your body, then you could give them the body’s cell markers and send them in to kick butt throughout your numerous lymph-passageways.

You could grow multi-cellular “meat” in a vat of oxidized sugar-water (after making sure you seal off the tank from other less tasty opportunists, like mold and rot). You could probably create new culinary experiences of extremely interesting variety and texture by controlling how your organism goes together. You could use a multi-cellular organism to produce any sort of conceivable organic molecule assuming you can tell a ribosome or a protien how to turn it out.

However, the disadvantages of biological nanotechnology are also the disadvantages of life. Some of the difficulties that I forsee in using them to construct macroscopic devices are given below:

1) It’s not going to be instantaneous. In fact, it’s not even going to be all that fast. If you plant your crop of car bodies in May, they might be melon sized by June. If it’s in a vat of fuel, it may grow faster, but it’s not going to be as fast as a big blunt stamp on sheet metal.

2) How do you say 14.5 inches +/- 0.001 across in a self-organizing pattern language, like you would with DNA instructions on how to organize and grow? Life forms up and grows according to patterns. It usually assembles and iterates out the pattern, then begins growing according to the pattern to the best of it’s ability.

If you, say, planted a crop of bio-nano-replicators that are supposed to assemble the copper sludge in the bottom of a nutrient tank into regenerative rocket nozzles, then your rocket nozzles are likely to come in as varied an amount of shapes and sizes as the tomatoes in your back garden. Some might be four feet wide. Some might be three feet wide. Some might have larger nozzles in relation to your combustion chamber. Some combustion chambers may not be exactly cylindrical. The throat area would vary as well. Some might be stunted. Mechanically, it would be a disaster.

Lastly, it’s not going to be effortless or free. It’s not going to provide people with free products and services, or pave the way for an economy where you can be a bum and reap the sorts of rewards inherent in this technology. This is because it is going to take a whole lot of sweat and effort to make these nanotechnology devices do what they’re supposed to. You’ll have to have macromolecule designers that figure out what you want these things to go into your body and do. You’re going to have biological programmers that figure out how to encode what you want the bacteria to do in the madcap language of DNA and RNA. You’re going to have trial runs to see if these replicators do only what you intend them to do (rather than having your mind machine interface organism setting up shop in your kidneys and growing tumors as well, or your macromolecule factory bacteria producing not just some miracle drug, but also a nasty allergen while it’s at it). You’re going to have nano-device farmers that take the finished product out of the tanks and cut off all the assembly sludge, waste products, and unneeded tissue. All these people will want to be paid. They’re not going to be impressed with this classless economy nonsense.

I envision nanotechnology being primarily used for fine control. For going in and producing biological effects of extreme complexity. For producing small devices of similarly extraordinary complexity. For farming out macromolecules, or growing food tissue, or being used as a biological recycling mechanism for life support.

But I don’t envision it as being used to grow cars and construction equipment. If you need to bend metal, you’re probably better off having a macroscopic robot pick up a macroscopic hammer (or die) and go at it the old fashioned way.

Well, that's my long winded opinion. What do you think? Discuss. Discuss, I say!!

3-Vector Source Code

2006-07-16T09:57:00.000-07:00

Speaking of software, since I am sort of on a programming theme lately, here is a C++ class that I wrote a few years ago when writing a 3-D orbital simulator. It's for a 3-vector, and contains many useful 3-D vector operations (such as cross products, rotations, abs values, projections, ect) that make doing the math easy.

Additionally, this class should be easy to use because it's small, simple, and doesn't call on a whole lot of obscure stuff. Furthermore, it's not written in obscure C++, doesn't abuse whitespace insensitivity, and doesn't inherit the whole windows API. Using someone elses code in a pinch is always tedious, but hopefully this will make it easier.

Vect3.hpp
Vect3.cpp

Enjoy. For all you CS majors, don't laugh at my code.

Rocket Calculator

2006-07-15T17:50:00.000-07:00

Some of you may remember my beginning a program sometime last semester that would size rocket stages for a multi-stage rocket. Well, I start a lot of programs, I don't often finish one. And it's never really done anyways, it's always "in progress".

This is a program that takes information about rocket stages (payload mass, inert mass, isp), then calculates the distribution of Isp between them that results in the lowest overall rocket mass. Debugging this program should have been simple, but it's never simple. When I write programs a certain way, it takes me 10 times as long to debug them as it does to write them.

Here is the source code. Compile it as a console/command line executable, and enjoy.
Rocket Calculator

In addition, I've noticed that having a handy unit converter is also useful when working on aerospace problems. We invented the airplane, and pushed the boundaries of space exploration, and now you're stuck with our crazy unit system. HA! Anyway, I haven't tested this completely, so don't use it to guide any mars spacecraft or anything without checking first. Just input the number of units in the input column and read across.
Unit Converter.xls

Lunar Fluids

2006-07-07T21:11:00.000-07:00

/Since volatiles are rare on the moon, and fluids are needed for many many applications, from heat exchange, to hydraulics, to sealing interfaces, a very useful thing to do would be to develop some sort of in-situ fluid that could fill some of these roles. It would have to be able to be produced from silicon, oxygen, titanium, iron, ect. The primary constituents of the lunar surface (Or at least stuff you can find in > PPM quantities). If a permanent settlement is to have fluid loss, it’s better to use something that can readily be replaced in abundance in seals, sliders, and rotating equipment.

So many liquids that we use every day are loaded with hydrogen. Anyone know of some chemical that could fill the bill?

I know that microscopic silicon spheres are used as a lubricant, but I’m not certain if they could, for instance, wet gaskets to prevent air from leaking from a chamber under pressure or something. It certainly won’t make a heat transfer medium for powerplants and heat exchangers, seeing as how silicon has about 1-1.5 W/m^2 (MATWEB) heat transfer coefficient! It also wouldn't be much use as a cleaner, seeing as how the lunar dust behaves similarly.

Maybe the same sort of thing could be done with iron, aluminum, or other metal – making microscopic spheres out of it to turn it into a pseudo-liquid for heat transfer purposes. However, having such a heat transfer medium lock up on the job, like the graphite in Chernobyl would be bad.

Perhaps liquid phosphorous or sulfur could be used. It would have to be heated, but has a low melting point. (111C, 219C respectively, http://www.space-rockets.com/moon1.html) For things like doors, you could possibly melt it and freeze it upon opening and closing the door, hermetically sealing your environment. But for piston rings, ect, it might not be the best idea. On second thought, it would oxidize like crazy with the gasses that they're sealing, not to mention burn if they got inside the habitat. Maybe lead?

Just thinking out loud. Let me know what you think in the comments section. In any case, the engineering challenges of settling space are likely to be complex and unanticipated to a large degree. We'll have to figure it out as we go, and we will have to go first, long before we know everything about what we're doing.

Lunar Dust Issues

2006-07-07T21:06:00.000-07:00

The summer 2006 edition of The Bent, Tau Beta Pi's magazine, has an interesting article on Lunar dust that I thought I might comment on. (“True Grit: Unearthly Dust”, Trudy E. Bell) According to some theories, with support from lunar prospector, the lunar dust gets charged by the incoming solar wind and elevates off the surface. The Apollo astronauts apparently observed this phenomenon, which resulted a slightly blurred horizon, and reflected light just before sunrise. The Apollo astronauts observed streamers of light over the horizon. These phenomena are typical of an atmosphere, and were not expected on the moon.

This charging is uneven across the lunar surface from the sunward pole out. This charge differential between the near and far sides may lead to dust currents across the entire surface.

If these electrostatically elevated particles of dust can soften the horizon and reflect light, I wonder what implications this has for the use of the moon as a pristine observatory (as is often alluded to as a potential activity of interest for the lunar far side)? Astronomers have been interested for years in the use of the lunar far side as a potential observatory. Even though space telescopes get above the atmosphere, emissions from our planet in the form of radio waves and reflected light prevent our instruments from reaching full theoretical potential. The lunar far side blocks out all emissions from Earth and from the Sun during its long night. The dust currents may cover instruments, and the dust may also obscure the views of telescopes which require near-perfect vacuum.

Also, I was thinking this may have implications for solar panels. Dust deposition may take place over long periods of time on the panels, and need to be wiped off.

-----Separate topic
The lunar dust is highly abrasive. It’s like the sand in a bead blaster. The article touches on this topic somewhat as well. Wiping the dust off of delicate surfaces can result in scratches. It also seems to get into everything, according to the Apollo astronauts. The article suggests using an electrostatic repulsion system to clean the dust off of surfaces. Charged panels, or charging guns may make a good first line of defense to remove the dust in the most gentle manner possible.

French Terror Alerts

2006-07-05T18:16:00.000-07:00

So Funny. So True.

4th of July 2006

2006-07-04T08:05:00.000-07:00

Happy 4th of July!

Here's to America: The best nation on Earth!

Here's to the outrageous good fortune that we had to have our founding fathers, men of unparralelled genius, bravery, and integrity, be the authors of our constitution and founders of our nation. Men who had unlimited opportunities to seize the reins of power and didn't. Who had every opportunity to dissolve the union and pursue the government of their choosing, but saw that the long term security, integrity, and greatness of our nation required that it remain united. Men, like Washington, who could have been king, but dissolved his army and went back to his farm, unlike any other victorious general in history.

Here's to the nation that gave its people liberty. That freed them of the constraints of serfdom and slavery. That never thought to dictate the purpose of the lives of it's citizens with dogma and ideology. That recognized the fundamental rights of life, liberty, and the pursuit of happiness, as essential to the dignity of mankind.

Here's to the nation, whose citizens, freed from the tyrrany of heresy and illegal thought, invented the modern world. Freed from the need for approval and status, built the modern world. Who dug the Panama Canal to link the oceans, lofted the skyscrapers to dominate the city skylines, fed the world, invented the airplane and landed men on the moon!

Here's to our soldiers who liberated our own nation, and afterwards proceeded to liberate the world. We overthrew the aggression of Germany not once, but twice. We took control of all of Europe - and gave it back! We conquered Japan, pacified it - and gave it back to it's people! The Korea which we succeeded in liberating today stands in such stark contrast to the Korea that we didn't that the border between the two can be clearly seen from orbit (esp at night). Here's to the only nation on earth with the ability to easily be an empire, with the ability to effortlessly crush the resistance of the world, but completely devoid of the will to do so!

Here's to America and all it stands for! Happy 4th of July!

Future Car Visions (The debate)

2006-07-03T13:44:00.000-07:00

A relative of mine recently told me of some thoughts of his on future driving. It turned into a mini debate on the merits and feasibility of his vision versus what I thought would or wouldn’t work. I shouldn’t be such an “old fogey” in those debates. I am somewhat skeptical of some of the points of his vision, but I should attempt to frame them more as improvements on his plan.
Perhaps I can articulate it better in writing (I usually can) the sort of things I have in mind.

My relative’s opinion is that the future of driving is one of the cars being controlled by a satellite computer network. These satellites will give the car information about the road, the cars around them, and give them their instructions on how to drive, operating sort of like air traffic control for planes. The cars, thus coordinated, would travel without human intervention, be able to sustain higher speeds without accident, and would never have accidents due to human error again. In his opinion, it’s safer for the cars to operate without the human having the ability to control the car than with due to the ability of modern programs to handle the information given to them. People are idiots. They get into accidents, their attention wanes, they drive drunk, they talk on the cellphone when they should be paying attention to the road, they ride people's trunks.

In my opinion, there certainly may be a role for computer control of cars, but some parts of his vision could work better if approached with a different philosophy. First of all, air traffic control, IMO, has a lot to learn from the way roads are operated than the other way around! Air traffic control deals with maybe 5000 aircraft over the sky of the entire United States at a time. It coordinates their movements, and directs their altitudes. However, aircraft can operate at many altitudes without terrain considerations at all. The problem of directing aircraft is simple compared with directing automobiles. And our skies are considered crowded! In contrast, there are 200 million vehicles operating in the United States. They all operate every day. They all pour out onto the road during rush hour, and they all have a very specific individual destination in mind (as opposed to a relative handful of airports). Each of these vehicles must navigate construction zones, other impassable vehicles at (comparatively) immensely close proximity, impassable barriers, unexpected obstacles (kids, bicycles, pipes sticking up out of the road for no apparent reason, pedestrians, storm debris). Each of these vehicles manages it every day without any coordination at all. The reason why they can perform what would be a monstrous command and control nightmare to dwarf by several orders of magnitude the air traffic control problem without any grand central traffic cop, is because every car operates according to some simple and mutually held road rules. This may sound trivial, but it’s not. The cars concern themselves with their immediate situation. They encounter localized road situations (intersections, merging, ect), and operate autonomously according to predefined rules (the cars going straight have to go before the cars turning left can go, turns yield to through traffic). This enables an arbitrary number of cars to proceed through their day to day business without burdening central control at all with an extra vehicle to maneuver. The amount of communication necessary to navigate the car drops. Each car is responsible for it’s own computation. This enables vehicles to operate locally and autonomously, rather than concerning themselves with the global traffic situation and being confined by it.

The cars on the road right now don’t need to communicate with a centralized network. The range, number, and volume of their communications is far less than what would be required for centralized control. As it is now, the vehicles only need to send and receive information to the cars immediately surrounding them. 200 million vehicles, all talking at the same time to the same computer system that’s trying to direct them, wouldn’t work out so well. 200 million computers can talk to the internet, because they’re each talking to an individual server, each requesting independent operations. The traffic control problem would need to be solved in such a localized manner, rather than all together as a coupled problem. With localized control, the cars could serve with their own computing power, rather than needing a super-supercomputer in each city to mange it.

The third nit-pick that bothered me is that the cars are all talking to a network to get their information about the world. Supposedly the network contains all the information the car needs to know about the world. If the car gets it’s worldview from the network, where does the network get it’s worldview? What happens when a storm blows through and puts a branch in the middle of the road? What happens when the road crew takes out your overpass without informing the network? (Visions of cars cascading over the side of a cliff) What happens in the inevitable accident when the car fails? (And the cars will fail. The system has to be tolerant of mechanical failure as well as lack of information). How will this network handle a kid running across the street, or a deer bounding across the highway? The network is not the world. I don’t think it should ever be taken as a substitute for the world. If cars have the capacity to operate themselves, they need to demonstrate it by reacting to the world as it is, not the world as a network thinks it is. They need to take in the immediate, local sensory information on the ground and process that, because a glorified road map will never have information to that detail. It just won’t have the sheer level of sensory capacity for it. Even if it does, it’s more effective to just stick the necessary sensors on the cars anyway. This ensures the senses are where the car is, and that the cars can handle non-upgraded roads as well as high-tech modernized roads.

My fourth nit-pick is that this system needs to be tolerant of drivers that aren’t operating on the central-control method. It needs to be able to be gradually phased in. You aren’t going to replace 200 million vehicles, or the highways, in a massive sweeping movement. You’re not going to be able to ground all the cars in the country until they are all equipped with robotic control systems. Your car has to be tolerant of idiot drivers anyways, even if your opinion is that people are too clumsy to operate a car, because it’s not going to have a road clear of all vehicles but ones operating according to the central control. Localized autonomous control of vehicles is so much more robust and requires so much less effort than a centralized control network. IMO, this is the way to go. If your car is autonomous, it should be able to handle what any driver can handle. This is so much more robust.

Final nit-pick – humans have demonstrated the capacity to operate their vehicles just fine. Robots haven’t demonstrated the capacity to operate in the real world to that degree yet (though I don’t doubt that they will be capable eventually). “People are idiots”, may apply, but even idiots are incredibly aware of their situation compared to the most decked out robots. Furthermore, people can gain an understanding of their situation to a degree that a program may not. I’m not saying that people should always grab manual control I’m saying that they should always have that option. Always. On any device that they are operating. Because the people maybe, maybe, just know something about what is going on in a particular scenario (esp. in particularly dangerous, unusual ones) that their programs don’t. A programmer in an office building may be able to take an impressive number of scenarios and situations into account, and may be able to develop some very nimble and responsive algorithms, but they aren’t there looking at the problem, on the scene. The whole point of having these vehicles and machines in the first place, is to get them to do what we need them to do, not what their manufacturer thinks we should do with them. They are tools for the use of the user, not the designers, and ultimately, the user should have control.

Okay, so that was more of a debate. But I still think these principles are more sound and robust than the ones laid out in the original vision of air-traffic-controlled vehicles.

Risk and space travel

2006-07-02T10:42:00.000-07:00

http://article.nationalreview.com/?q=MmJmNjg1YWQyN2I3OTUxYTU4ODcyZDUxNjE5MjM1OTE=

This article points out soemthing important about space travel and risk management that is important to consider. I would recommend reading it.

Here is a copied part debate I had a few years ago on a space forum that I post on sometimes. It seems very relevant to the issue:

Me, responding to a post about generating more and more fail-safes.

Backups cost money. There must be a balance between safety and cost
effectiveness, or it won't be reasonable to do. Take the shuttle for
example...theoretically, you could make it 100% safe, but only after spending
infinite money and attention on every aspect. But we can't operate a space
program that way, so their has to be a trade-off. Somewhere, somehow, somone has
to make a decision about what constitutes an acceptable risk. Personally, I
think that should be made by the people who want to ride the thing.

Nzilla:

Between money and lives, I'll choose lives every time. No cost is too high to
ensure absolute safety.

Me:

A nice ideal, I guess. I am biased towards the life end. But if you take it
absolutely, then you would have been opposed to exploring the world in sailing
ships, lighting fire, driving cars, laying railroads, mining, in short, every
activity involving a potentially harmful result.

Nzilla:

At this point in time, we have the technology to make it safe. It just cost too
much, so we cut back. But on a permanent base, i think no expense should be
spared.

Pulsar:

I would agree with ASEI here, there must inevitably be some sort of trade off.
You could spend an infinate amount of time/money making everything safe, but it
can only be achieved at the expense of progress. This is why the great pioneers
of the past are still famous and admired today, they accepted that there was
only a certain level of precautions that could reasonably be taken - and they
took the risk. What we learnt from them allowed the journey to be safer next
time. This is what pioneers are. You obviously have to make things as safe as
you reasonably can, but for many the risks make it worth doing. As for a
permanent base, it is difficult to comment, as everyone would agree that we do
not have the fail safe technology to even attempt this right now. When we start
putting the general population up there then there can be no 'accidents' and
until we have fail safe technology it may be necessary to have a backup - or at
least a way out available should it be needed.

....
Another post of mine about space settlement or commercialization of a human presence in space:

I think if space is ever to be settled or commercialized that there needs
to be a cultural attitude of risk-taking. It doesn't necessarily mean that we
shouldn't value life. What it does mean is that people will need to be willing
to take personal risks, and accept the results of those risks. If a man gets on
a rocket, the attitude needs to be that he knows and accepts the risks of space
travel. If afterwards, the rocket explodes and he dies, the blame cannot lie
with the company that built it, they did their best to the greatest degree
reasonable in serving the interests of their customer. Currently, any risk is
deemed unacceptable. When risks are taken by people, the responsibility never
rests squarely on them. Through our legal system, revenge is usually taken on
the companies which enable the risk rather than the people who take it. The
result is that it becomes far too risky for anyone to provide any product or
service to which there is the slightest degree of risk to the consumer (at
least, at any price that is reasonable and viable).

2006-06-17T09:06:00.000-07:00

It is not, however, my design to dwell upon observations of this nature. I am well aware that it would be disingenuous to resolve indiscriminately the opposition of any set of men (merely because their situations might subject them to suspicion) into interested or ambitious views. Candor will oblige us to admit that even such men may be actuated by upright intentions; and it cannot be doubted that much of the opposition which has made its appearance, or may hereafter make its appearance, will spring from sources, blameless at least, if not respectable--the honest errors of minds led astray by preconceived jealousies and fears. So numerous indeed and so powerful are the causes which serve to give a false bias to the judgment, that we, upon many occasions, see wise and good men on the wrong as well as on the right side of questions of the first magnitude to society. This circumstance, if duly attended to, would furnish a lesson of moderation to those who are ever so much persuaded of their being in the right in any controversy. And a further reason for caution, in this respect, might be drawn from the reflection that we are not always sure that those who advocate the truth are influenced by purer principles than their antagonists. Ambition, avarice, personal animosity, party opposition, and many other motives not more laudable than these, are apt to operate as well upon those who support as those who oppose the right side of a question. Were there not even these inducements to moderation, nothing could be more ill-judged than that intolerant spirit which has, at all times, characterized political parties. For in politics, as in religion, it is equally absurd to aim at making proselytes by fire and sword. Heresies in either can rarely be cured by persecution.
And yet, however just these sentiments will be allowed to be, we have already sufficient indications that it will happen in this as in all former cases of great national discussion. A torrent of angry and malignant passions will be let loose. To judge from the conduct of the opposite parties, we shall be led to conclude that they will mutually hope to evince the justness of their opinions, and to increase the number of their converts by the loudness of their declamations and the bitterness of their invectives. An enlightened zeal for the energy and efficiency of government will be stigmatized as the offspring of a temper fond of despotic power and hostile to the principles of liberty. An over-scrupulous jealousy of danger to the rights of the people, which is more commonly the fault of the head than of the heart, will be represented as mere pretense and artifice, the stale bait for popularity at the expense of the public good. It will be forgotten, on the one hand, that jealousy is the usual concomitant of love, and that the noble enthusiasm of liberty is apt to be infected with a spirit of narrow and illiberal distrust. On the other hand, it will be equally forgotten that the vigor of government is essential to the security of liberty; that, in the contemplation of a sound and well-informed judgment, their interest can never be separated; and that a dangerous ambition more often lurks behind the specious mask of zeal for the rights of the people than under the forbidden appearance of zeal for the firmness and efficiency of government. History will teach us that the former has been found a much more certain road to the introduction of despotism than the latter, and that of those men who have overturned the liberties of republics, the greatest number have begun their career by paying an obsequious court to the people; commencing demagogues, and ending tyrants.

- Hamilton, Federalist Papers #1

Some things never change. The things that don't often provide an interesting perspective on the modern age.

I'm going to take a break from reading my usual political blogs, and go through the federalist papers and other interesting historical documents. If you ever get bored with yours, there is an incredible wealth of interesting stuff, from time periods ranging from the bronze age to turn of the century, available for free online.

About those GCRs?

2006-06-10T09:23:00.000-07:00

I've often heard of radiation given as an "insurmountable" problem to getting men to mars. Or even sending them back to the moon. And yet, people spend months at a time on the ISS, orbiting the Earth above the atmosphere. In terms of uncharged radiation, they should be getting about half of all the stuff that Mars or moon astronauts would get (The earth shields the sun about half of the time). The only type of radiation that space station astronauts aren't getting in equivalent quantities are the charged radiation due to the van Allen belts sheilding them.
The main radiation culprit fretted over are galactic cosmic rays - very energetic free nuclei that have the energy to punch through most shielding, generating secondary particles as they go. The thing that gets me though, is that nuclei are all charged. If a planetary magnetic field is enough to shield you from GCRs while in low earth orbit, why can't you just set up your own magnetic field to deflect charged radiation?

A little back of the envelope non-reletavistic highschool physics says that a magnetic field of strength B would deflect a particle in a loop of radius r = mv/qB. You would have to make the field stronger to cause tighter deflection, but the particles should loop around the field lines until they impact the magnet.

Doesn't sound so insurmountable to me. Furthermore, it sounds a whole lot more reasonable than lining your crew cabin with 10 feet of lead. You're going to have to have a reactor on your mars spacecraft to power propulsion anyway. If you take more payload weight (all the shielding), you'll have to spend a lot more energy on propulsion to accelerate. If you can save on payload weight by having lighter shielding and a magnetic shield, I wonder if it makes more sense to spend some energy on that instead?

Just an idea. Correct me if I'm wrong. (The magnet would have to be too energetic/ other serious radiation threats/ ect)

Presenting the new and improved: Ideal Rigid Connector!

2006-04-26T11:55:00.000-07:00

Have you ever tired of flawed, weak, ordinary matter, that yields, and fractures, and melts? Have you ever wondered precisely what would happen in a given engineering scenario, or chafed that your materials did something entirely different from your first order idealized analysis? Have those pesky nonlinearities, inconstancies, and tightly bound performance envelopes of flawed earthly matter ever ruined your perfect plan? Well, with the new and improved ideal rigid connecting rod, all this is about to change! The Ideal Platonic Form Corp (LLC) (patent … uh … pending) Ideal Rigid Connecting Rod is made from new and unimprovable Idealized Matter ™. The properties of which are given below:

Ideal Matter - Physical Properties Summary
Yield Stress infinity MPa
Ultimate Stress infinity MPa
Cp infinity J/kg-K
Thermal Conductivity infinity W/m-K
Density 0 kg/m^3
Hardness infinity Brinell
Young's Modulus infinity MPa
Shear Modulus infinity MPa
Poisson's Ratio 0.33333
Electrical Resistivity 0 Ohm-m
Melting Temperature infinity K
Radiative Emmissivity 0
Fracture Toughness infinity MPa-m^0.5
Thermal Expansion 0 m/m-K

Your ideal rigid connector is made of 100% pure Idealized Matter, with two 1-cm diameter Ideal Ball-and Socket Joints (patent … uh… pending) on the end for interface. Of course, the development of Idealized Matter did not come about without a lot of effort. The initial production process is a strict secret. One of the chief difficulties was machining idealized matter into a usable form. Obviously, with infinite hardness and yield stress, not to mention fracture toughness, putting a dent in the material is a challenge. Known physics still does not tell you what happens when you try to machine Idealized Matter using Idealized Matter.

Fortunately for us, several blunted diamond drill bits, fried chemical pulse lasers, and destroyed carbide lathe tools later, we developed our unique Magic ™ Machining Process, whereby … something happens … and the final product comes out as per the drawing below!

An initial problem working with the matter was its identically zero density. The velocity of the material ended up being unconstrained by the forces exerted on it, leading to some unfortunate incidents with it accelerating instantly to the speed of light. This prompted us to put a bit of normal matter into the interfaces on the end.

Work with the initial Ideal Rod was delayed due to some unfortunate incidents attempting to interface to a zero radius part of infinite hardness and apply any meaningful resisting load. The original rod, unconstrained by either gravity or the ceiling went sailing off into deep space at the speed of light. To rectify this, the Ideal Ball and Socket Joints were added to manipulate the object.

Advice for using your Ideal Connecting Rod:

Never attempt to interface with the zero diameter rod portion of the rod (unless you want to use it as a cheese cutter). Also, do not attempt to weld or bond to the rod, since the material will not melt, and has a zero surface friction coefficient – it simply will not bond.

If you live in a state where the laws of physics are recognized, you could face severe civil and legal penalties for the unauthorized use of Idealized Matter. Though on the surface, these physical properties appear to be unrelated to each other, the idealization of a property for several sets of first order analyses end up generating contradictory properties, or rendering other laws of physics indeterminate with respect to the behavior of the substance. The very existence of Idealized Matter ™ may violate other more general laws of physics. Examples include the yield strength/fracture toughness/hardness set, and the difficulty in determining the temperature of idealized matter due to its zero density and infinite specific heat capacity.

Due to it’s zero resistivity (Ideal Supercondctivity ™), we do not recommend waving the ideal rigid connecting rod around next to high voltage lines, or during a thunderstorm.

Ordering Information:

Your Ideal Rigid Connecting rod is available at the low low (ideal) price of $0.00. Make your checks payable to the Ideal Platonic Form Corp (LLC), and send to our mailing address below:

381 Thisisnota Street
Espamville, Nigeria, 000-0000

By way of
1239 Lolwhatasucker Bvd.
Townonfastwheels, Dirkidirkistan.

(***NOTE: For those of you too devoid of humor to recognize that this is a joke - this is, in fact a joke. Do not send money to Nigeria (or Dirkidirkistan). If you do, don't come threatening me with a lawsuit).

You might be an engineer if.....

2006-04-23T21:19:00.000-07:00

You have no life - and you can PROVE it mathematically.
You enjoy pain.
You know vector calculus but you can't remember how to do long division.
You chuckle whenever anyone says "centrifugal force".
You've actually used every single function on your graphing calculator.
It is sunny and 70 degrees outside, and you are working on a computer.
You frequently whistle the theme song to "MacGyver".
You know how to integrate a chicken and can take the derivative of water.
You think in "math".
You've calculated that the World Series actually diverges.
You hesitate to look at something because you don't want to break down its wave function.
You have a pet named after a scientist.
You laugh at jokes about mathematicians.
The Humane society has you arrested because you actually performed the Schrodinger's Cat experiment.
You can translate English into Binary.
You can't remember what's behind the door in the engineering building which says "Exit".
You have to bring a jacket with you, in the middle of summer, because there's a wind-chill factor in the lab.
You are completely addicted to caffeine.
You avoid doing anything because you don't want to contribute to the eventual heat-death of the universe.
You consider ANY non-engineering course "easy".
When your professor asks you where your homework is, you claim to have accidentally determined its momentum so precisely, that according to Heisenberg it could be anywhere in the universe.
The "fun" center of your brain has deteriorated from lack of use.
You'll assume that a "horse" is a "sphere" in order to make the math easier.
The blinking 12:00 on someone's VCR draws you in like a tractor beam to fix it.
You bring a computer manual / technical journal as vacation reading.
The salesperson at Circuit City can't answer any of your questions.
You can't help eavesdropping in computer stores... and correcting the salesperson.
You're in line for the guillotine... it stops working properly... and you offer to fix it.
You go on the rides at Disneyland and sit backwards to see how they do the special effects.
You have any "Dilbert" comics displayed in your work area.
You have a habit of destroying things in order to see how they work.
You have never backed up your hard drive.
You haven't bought any new underwear or socks for yourself since you got married.
You spent more on your calculator than on your wedding ring.
You think that when people around you yawn, it's because they didn't get enough sleep.
You would rather get more dots per inch than miles per gallon
You've ever calculated how much you make per second.
Your favorite James Bond character is "Q," the guy who makes the gadgets.
You understood more than five of these jokes.
You make a copy of this list, and post it on your door (or your home page !) (Just did)

Short Post

2006-04-23T09:19:00.000-07:00

Finals coming up... (and I'm trying to learn Java in my free time). Don't have a lot of time to post.

But, I just wanted to comment on something that sort of left an impression. I've noticed the expression "personal library" used to describe the collections of books that we buy and read. And anymore these days, it's true! I myself have accumulated a library worth of books that I've read (and not all of it is novels either)! Books, along with my computer, make up some of my most frequently used personal possesions.

These days, literature, novels, papers, information, if not available for free online, are easily accessible in print at a library or published for a reasonable price elsewhere. We have become ravenous readers.

Furthermore, the success and ubiquity of bookstores is another indicator that something is going very right with respect to our culture. It says something slightly different and more concrete than libraries (though the widespread use of those is also a good sign). The old kingdoms of medieval europe had libraries, but it didn't always translate into a well informed and literate population, just that the patrons thought it was a good idea. The fact that bookstores are doing so well in the modern first world is an indication that we are willing to pay for our literature, that there is a genuine interest in it.

Just something to think about, and be thankful for the next time you look at a bookstore.

Anyway, enough procrastination, back to work...

Lunar Hydrogen Revisited:

2006-04-03T11:22:00.000-07:00

Okay, I’ll have to eat a little crow here. Hydrogen is not as scarce on the lunar surface as I had previously believed. I was using information from some Apollo era books in our library on the composition of the local geology. However, the recent Lunar Prospector mission has revealed the presence of significantly better deposits of hydrogen in the “cold traps” of the lunar poles, areas of perpetual shade generated by crater walls where temperatures are cold enough for the hydrogen to condense.

Lunar prospector used the scattering of epithermal neutrons, and their absorption by hydrogen deposits in the soil, to detect the hydrogen deposits. If the conclusions of the following report are accurate, there could be on the order of 10^8 metric tons of hydrogen on either pole of the moon. This much hydrogen could easily support lunar bases. It could also support a few thousand nuclear thermal space missions using nuclear derived hydrogen fuel before being completely expended. This offers far better prospects for initial settlement of the moon and its use as a fuel base for missions farther out into the solar system.

Lunar Prospector Hydrogen Report

It was also mentioned somewhere else in some of my more speculative reading that cold traps may be constructed for industrial purposes, and that this could attract hydrogen from the solar wind to pool in the shade (though how slowly, I am unsure).

An additional resource: The map of neutron scattering.

NASA Data Maps

I've been blogrolled!

2006-03-25T18:12:00.000-08:00

Yes! I've been added to a blogroll! Maybe now I'll get some traffic. Of course, to keep it, I'll also have to post regularly and be interesting or something. A perpetual challenge for an engineering student (who should always be doing some other project right now, regardless of when right now is).

Thanks Ed.

The problem with...

2006-02-09T03:07:00.000-08:00

The problem with being an engineering student and having a blog is that you never have time to post! Here's to two all nighters a week and three seperate stacks of homework!

Stardust Probe Returns

2006-01-09T15:09:00.000-08:00

http://www.nbc11.com/news/5955879/detail.html

The stardust probe conducted a flyby of comet Wild 2 and collected samples of the outgassing material. It will return to earth on 15 Jan, where its sample capsule will land in Utah.

Hohman Transfer Calculator

2005-12-28T20:45:00.000-08:00

Here's a little thing I put together a few nights ago. Nothing profoundly useful or complicated about it, though it may come in handy. It's an excell spreadsheet used to calculate the total delta v and transit time to make a hohman transfer between two circular orbits.

Hohman Transfer Calculator

The Moon-Comet Run

2005-12-20T20:13:00.000-08:00

The need for Hydrogen

One of the main problems with living on the moon is a lack of hydrogen. The moon doesn't lack in oxygen (in the form of various metal oxides, not to mention sand). It doesn't lack in carbon (various carbonates). Nitrogen should be easy enough to obtain from Earth's upper atmosphere if it's not already present in lunar minerals. But the moon is almost entirely devoid of hydrogen. Without hydrogen, you don't get water, you don't get nuclear thermal rocket fuel, you don't get engine grease, adhesive, oil, ect. That’s why NASA is looking for polar ice deposits so hard.

The moon has a very very small trace amount of hydrogen in the regolith (parts per million). All the rest of it has boiled away. It may be possible to microwave that hydrogen out of the soil and collect it by covering a lot of surface area. This would definitely be a non-renewable limited resource: not the type of thing you want to blow away by the ton as rocket fuel. This can probably be enough to support a base in the early phases of settlement, assuming an efficient extraction vehicle is developed. However, the primary attraction of setting anything up on the moon at all is as a way-station and shipyard for expansion further out in the solar system. Without a source of rocket fuel, the moon is about as useful as a space station – not very.

Note -- the moon probably can function as a source of rocket fuel for nuclear electric ion engines. Ion drives usually can be designed for a wide variety of ions. Because no direct thermal expansion is involved, ion engines don’t need to use low-molecular mass fuels. In fact, heavier ions are easier to ionize. However, the type of engine I had in mind for fueling was a nuclear thermal engine. Nuclear thermal engines produce moderately high thrusts (much more than you’ll ever get out of an ion engine) at very nice Isps (800-1100 sec or so). But they need hydrogen for fuel, or their Isp and thrust quickly spiral down the toilet. (Exhaust velocity (hence Isp) scales roughly with the square root of molecular mass) For manned missions, a NERVA engine can get you where you need to go blazingly fast at nice mass fractions.

One of the suggested sources of hydrogen for the moon is to mine near Earth comets. In this post, I want to take a look at the logistics of making a moon to near Earth comet run.

Delta V Requirements to get there from the Moon
Or, more poetically: Catching the Comet

First of all, one of the things about the inner solar system is that, unless you are under an atmosphere, water sublimes away. That’s why the moon doesn’t have ice covering its surface like the outer solar moons do. So “near Earth” comets don’t stay near Earth for very long – or they would be gas clouds. They usually orbit the sun at very high eccentricity (having their source in the Kupier belt at 30+ AU from the sun). This means that any mining that takes place is not going to be a fixed base operation. A ship will have to go to a comet, do it’s business, then get back to the moon, and wait until another comet passes by. (Unless you feel like waiting 300 years for your equipment to come back into the inner solar system.) That’s okay though, because there are thousands of near earth objects, one is bound to be in the neighborhood any given year or so.

The dv requirements for meeting up with a high eccentricity comet are quite high however.
- The Earth-moon system orbits the sun at 1 AU. (1 AU is about 1.496E11 meters).
- The sun’s mass is 1.99E30 kg.
- Newton’s Gravity constant is 6.67E-11 Nm^2/kg^2

Suppose a comet happens to be passing by Earth’s orbit (1AU) from it’s home of 30 AU. Semimajor axis is 15.5 AU. Eccentricity is 0.935. Earth is going sqrt(G*Msun/Rearth) = 29786 m/sec tangent to the sun in it’s orbit. The comet, on it’s close approach will be going sqrt(G*Msun/Semimaj*(1+eccin)/(1-eccin)) = 41439 m/sec. This means to catch the comet, an increment of 11650 m/sec in your velocity is required with respect to earth. This is only part of the dv requirements though.

Let’s suppose our hypothetical comet miner is nuclear thermal powered itself (so that it can use the fuel it mines, among other things), and its mission is to take off from the moon (1600 m/sec), break Earth orbit (1439 m/sec from the moon), rendezvous with the comet, then use it’s nuclear engines in a power producing mode to power a hydrogen electrolysis factory. (Water is only 11% hydrogen by mass. It’s far more efficient to transport only the hydrogen). The hydrogen is liquefied and stored in fuel tanks onboard the vessel. Then the fuel miner accelerates back towards earth, re-enters the earth-moon system, and lands back at the moon. Also throw in 800 m/sec for maneuvering.

For the outbound leg, about 15500 m/sec dv is required. For the inbound leg, another 15500 m/sec dv is required. This is an extremely fuel expensive mission, even though we’re not leaving the inner solar system. (We could, assuming we get stranded near the comet on a trajectory out past Pluto). This is another reason why the high fuel efficiency of nuclear thermal is preferred over chemical propulsion.

Iteration 1 Vehicle IdeaThis vehicle will be sized according to the inbound leg. Since no one’s yet built a nuclear thermal rocket ship before, I’ll have to pull a few numbers out of my head.

The NERVA program back in the 60’s created and tested a series of nuclear rocket engines. These engines vastly outperformed even modern chemical engines in terms of fuel efficiency. They were intended as part of a program for upper stage and in-space vehicles to expand our presence in the solar system. A Saturn V with a NERVA upper stage could deliver a whopping 500 tons to LEO, and similarly massive amounts of cargo throughout the solar system. Unfortunately, the program was canceled in 73.

http://www.daviddarling.info/encyclopedia/N/NERVA.html

The NERVA engine weighs 30 tons. (I use metric tons btw. I’m using at as an abbreviation for 1000 kg). Even though NERVA 2’s Isp was 820 sec, recent material advances could probably push the operating temperature way up (uranium carbides, or other uranium ceramics could operate hotter without melting). This could lead to 1000 sec Isps in theory. I’m going with that, because it makes the final rocket look nicer.

Let’s also throw on a 10 ton computer/communications/hydrogen electrolysis payload.

Let’s say that since these fuel tanks will primarily operate under low acceleration – the weightlessness of space, or landing/launching from the moon, that they won’t need to be as structurally robust as our launch vehicles. A fuel tank propellant mass fraction of 0.95 will be used.

The Mass ratio required for the return leg is 0.2058. The payload fraction is 0.1640.

Let’s assume, for initial estimation’s sake, that we’re going to mine 500 tons of hydrogen off the comet as payload, and the rest as fuel. The rocket needs to mine a great enough weight in hydrogen off a comet to make up for it’s reactor and vehicle mass on a trip returning to a comet. Since it will use the very fuel it mines to get back to the moon, unload a fraction of it’s payload, and use the rest to get back to another comet, the percentage of payload that it can unload on the moon is proportional to the hydrogen payload to rocket systems mass ratio.

That 500 tons of hydrogen will also require 2615 tons of hydrogen to push it to the moon. It will also require 137 tons of tanks and structure.

The rocket, upon arriving and landing back on the moon can afford to unload 306 tons of hydrogen to a lunar base. It will need 194 tons of it’s payload to take back off and go chase another comet. 61% of the payload can be unloaded to the moon for other uses.

Looking at this vehicle more closely:

This rocket is a massive construction. It would make sense to invest in it only if you intend to run multiple missions from the moon to refuel interplanetary rockets. The nuclear reactor and the rest of the complex equipment would have to be launched direct from Earth. Hopefully there will be a way to construct the tanks and other structure (the “dumb” inert mass) using native lunar materials. This would require some sort of metal processing plant and construction yard present on the moon. A serious space effort would be needed to justify the moon comet runs.

On the positive note – if your space program is large enough to accommodate a moon-comet run, then it will become far easier to fuel your spacecraft. Hydrogen fuel from the moon can be used to power Earth-moon system tugs, and re-usable cargo vessels to Mars and elsewhere in the system. The moon can get not only hydrogen from comets, but also nitrogen and carbon, materials that should also be present in the ‘dirty snowballs’.

The file I used to play with the variables: Comettrip.xls

Why Colonize Space? Part 2 of 2

2005-12-15T21:17:00.000-08:00

3. What do we have to gain from humans in space?

Short term – not much beyond basic research

I’ll be the first to admit that, in the short term, it’s a daunting task to find a compelling reason to go. Economically, even the best prospects seem incredibly inefficient compared with developing an equivalent industry here on earth to serve earth’s population.

The argument that we’re running out of resources here on Earth is not a very convincing one. In terms of material resources, such as metals and rock, the type of resources we are likely to find in space, Earth has thousands of tons per capita available in readily extractable deposits. We simply are not going to run out of these. Rarer metals can be recycled quite easily from scrap (in fact, more easily recycled in some cases, than mined and refined). We may run out of oil, but we aren’t going to find oil in space anyway. We have sufficient deposits of uranium for the forseeable future. In terms of biological resources – we, the breadbasket of the world, aren’t using the majority of potential farmland available to us, and if we wanted to we could increase yields many times over using genetically modified crops, or farming more efficiently. Using crop rotations, we can harvest any reasonable quantity of wood needed and have it grow back in a decade or so. Pine trees are a type of weed anyway. And how are you going to do any of this better inside a space-limited dome on the moon or Mars?

The planets and moons available to us are stark barren wastelands. In the inner solar system, in terms of material resources available to a colony, you have variations on the theme of rock. Antarctica presents a friendlier face for would be colonists.

There are some methods that a space colony might have of generating income. These aren’t necessarily business-plan quality economic justifications of a space colony, but they can generate some cash and begin to pay back the earth for shelling out the resources to colonize.

A moon colony could build reflective mirrors out of the silicon and titanium in the lunar soil, run giant solar thermal plants, and beam the energy back to earth via a microwave or radio pulse. This would probably require relay satellites in geosynchronous orbit. Even though you could generate energy more efficiently by just building nuke plants on Earth, the Earth will never have a shortage in demand for energy. It will always be something that pays, for as long as civilization does industrial work. At present average prices (8 cents per kW-h), 10 GW of electricity would give you $200/sec. Of course, the inefficiencies involved in transmission might necessitate that a 10GW antenna on earth equate to a 100GW plant on the moon. But hey, $7 billion/year wouldn’t be anything to sneeze at. Already half NASA’s budget.

There are some interesting small-scale things we can do in zero gravity. We can reliably produce metal foams with small bubble geometry and no directional bias. We could conceivably produce some sort of biological products. That was the intent of some of the ISS experiments. If we could find something that we could only accomplish in zero-g, we could then justify a lunar colony on the basis of providing raw material to orbital factories. But I haven’t heard of anything yet. We need to get up there and start tinkering.

Medium Term

What is the purpose of running? It expends your body’s resources. It tires you. It requires your best efforts and exertion. But afterwards, you become fit. You learn to tolerate pain. You learn what you are capable of and what is required of you to perform. You are less prone to deteriorating health due to lack of exercise.

My argument is that in the medium term, exerting ourselves nationally to overcome the obstacle of space colonization will make our air and space capabilities fit, innovative, diverse (if the funding given meritocratically, which is going to be a bit of a challenge, in light of history). It will drive progress. It will also ensure that we maintain the ability to perform as we do. It’s harder to backslide technologically while pushing ahead. Basically, this is a rehash to my response to question 2.

Long Term:

In the long term, assuming that civilization confines itself to Earth, it will eventually (more distantly than in the immediate future, or even this century, but eventually) enter a zero sum situation. Probably not in terms of resources, but in terms of culture, in terms of what individuals can hope to build and achieve without stepping on each other’s toes. It would become a zero sum game in terms of what the best and brightest, most motivated could apply their efforts to. One company’s engineering achievement, say, a new jet-liner, could put thousands of aero engineers out of business for decades – because eventually in such a world, only one would be required to fill the entire niche. Without new industries being generated, or new products agitating the market, it would become a zero sum game in terms of the diversity of products and services. Expanding societies are healthy societies. Those that lose momentum tend to start caving inwards. There’s nowhere left for innovation to go, to grow to, away from the established society and culture, but up.

The solar system has the advantage of being absolutely huge. If we begin to develop a civilization that expands there, it will be long before we run up against similar boundaries.

Eventually, the probabilities are very small, and yet eventually, there may be another major asteroid strike on Earth. There are thousands of asteroids that orbit within the inner solar system. Our rather shell-shocked moon provides a myriad of examples of what a collision can do. 100 mile wide craters, the works. Defending Earth would be the ideal response to such a situation. Without a competently space-faring civilization capable of finding such asteroids on time, and sending enough H-bombs their way to vaporize them, we’ll probably end up being caught by surprise with minimal response time, and with no long distance launcher like the Saturn V to lob anything at it. We’d have to hope in a last minute explosion breaking the object up enough for our atmosphere to absorb the matter. It could still cause widespread damage (1000 1-mile wide craters vs 1 100 mile wide crater + massive secondary effects from shockwaves/tsunamis/ect).

A space faring civilization, one that has developed the capability to survive on bare rock and raw materials, that has refined it’s construction to the point where it can operate independently of nature, is a far more resilient civilization than exists at present, just as our civilization is a far more resilient civilization than the ancient Mycenians – who were forced into mass migration and invasion because of a climate change. Our technological development has enabled us to deal with more and more situations and disasters, and to inhabit and thrive in greater and greater regions of our world (not to mention thrive to greater and greater degrees). The ability to colonize space would mark a turning point in that, given raw material, we could conceivably survive anywhere. We would become, not just conquerors of new environments, but builders of our own environments. (Of course, we still have to do the work of getting to this point).

For that matter, we would also have the capability to expand to just about anywhere as well. Anything that could conceivably happen to Earth would not destroy a space-faring civilization.

(An additional, though somewhat odd point: a space-faring civilization would be immune from cultural nihilism and civilization collapse. Any degradation below a minimum competence in dealing with the environment, as well as any philosophy bent on opposing or destroying man’s constructive nature would result in death, hence would engage people’s survival instincts in preserving civilization. Perhaps this wouldn’t be total immunity, but I’d be surprised if a country run like Soviet Russia or North Korea could survive in space given that their people have or had a hard enough time surviving on Earth!)

Finally, in terms of the larger universe as a whole: While I hope life is abundant – that it resides wherever it possibly could reside, and that planets like Earth aren’t so very rare around other stars, we still have to face the fact that most of our own solar system is inhospitable to life, and that there is likely a large ratio of the wider universe that is also absolutely barren. Life has managed to conquer many niches, from high altitude mountain peaks, to hydrothermal vents in the ocean, to the interiors of volcanoes. So far, only mankind has managed to set foot and survive in space. All the ingenuity of life so far has only managed to allow it to survive beneath the thin envelope of our atmosphere, or the (comparative to the radius) thin oceans coating the surface of our planet. If we can accomplish our expansion into space, perhaps we will be doing it in the name of life on earth as well as human civilization.

(And doesn’t that sound like a sappy sound-byte that would go at the back of a documentary? :-P Oh well. I mean it.)

Why Colonize Space? Part 1 of 2

2005-12-15T20:15:00.000-08:00

This is a tough question. It’s one that I’ve been sort of sliding around as well in terms of my posting so far on this blog. But it’s also a very important one.

There are some halfway decent arguments against spending resources on a space program of any sort, much less one that puts the resources to sustain humans into the works – what with the endless list of requirements to keep them alive, to sustain them in the space environment, to subject them to the extraordinary dangers of space-flight. Several questions are posed regularly by those of this camp.

1. Couldn’t these resources be spent elsewhere on better things?

Space is expensive. It requires a lot to build rockets, and it requires a lot of rocket to get a small bit of matter where you want it to go in space. There are still people starving in Africa. People still die of malaria and bacteriological illnesses.

If we pose the question which should we be spending our resources on, space, or saving starving people? – the expected answer is saving starving people. But there’s a serious assumption there – that spending resources on “starving people” is actually going to alleviate starvation. There are many countries in the world that still have starvation, malnutrition, rampant disease, and that have populations that die like flies. They usually also receive upwards of 30% of their GDP in terms of resources designed to keep them from these very ills. They also usually have one other element in common: They are ruled by tribal or authoritarian despotisms which take that aid money and either burn it, leave piles of food to rot, or buy weapons with our charity and use them to terrorize their populations. The problem has never been one of “resources”. People who are free – who have their able bodies at their own disposal, usually never starve. There are instances where natural disaster or infirmity occasionally prevails. But they, under normal circumstances, never fail to at least feed themselves. Taiwan is a resource-less rock in the middle of the ocean – the Taiwanese don’t starve. South Korea is a harsh piece of terrain, yet South Koreans don’t starve. North Koreans do.

If we posed this question another way – would you rather, given circumstances favorable to doing so, spend your resources on either space colonization, or liberating people from tyrannies - I’d cheerfully divert the funding from my lifelong dream and spend my engineering talents, for part of my life, designing the new and improved despot-seeking-missile. (In fact, that’s what I hope to do). What mankind stands to gain, medium term, from eradicating tyranny is much greater than from a space program.

But there’s another problem with this question – it’s a false dichotomy. We spend $16 billion on NASA per year. We spend $2.5 trillion dollars on everything else. NASA is only 0.1% of our total federal spending. In contrast, we spend $400 billion per year in interest on our national debt! If we were going to trim something, there’s no shortage of places to start. Why cut the space program? Why challenge increases in the space program with starving children in Africa, but not federal highway maintenance pork? ($35 billion, most of which is probably pork, unleashed and running wild. BTW, we’re spending more to maintain the highways than we did to build them – figure that one out).

If we were the United States of NASA, and we spent 80% of our federal budget on space exploration, I’d want to cut the space program back down to a reasonable size too. I’d probably be blogging my discontent from an internet café on Mars, but even so – then starving children in Africa would be a valid point to raise.

2. Wait for Technology to Develop

The second argument that’s often raised against it is that we don’t have the technology to colonize space. We should wait until we have the ability to do it before making any serious efforts at climbing this mountain.

This argument is in error for the following reason: It assumes that Technology Just Happens, that men have a passive role to play in the development of technology, and that they do what they can when it becomes possible to do it. That’s not how it works. Capital T Technology doesn’t solve problems for us. Men develop technology to solve problems. I believe that our greatest technological advancements happened, not while we were waiting for them to happen, but when we were striving to overcome an obstacle. The oceangoing technology of our millennia of sailing was not invented, refined, or developed by abstract theorists in a land-locked university. Conversely, our knowledge of fluid dynamics came first to the Romans and the ancient Persians, who had to plumb their cities and irrigate their deserts. The steam engine wasn’t built for amusement. James Watt’s efforts to regulate the device were not born of abstractions, but practical experience and experimentation. Our greatest bursts of applied invention and innovation, of technological advancement, came first when we had the world to explore and understand, second when we had the continents to tame, and more recently when we needed to fight our wars and overcome the enemy.

To make no effort towards conquering space means that we will develop no technology making it any easier to do so. Our expertise in other fields may advance arbitrarily. But we will remain precisely in the position we are in now in terms of being able to put humans on other planets and moons and enabling them to live there. Having made no efforts to make this work, we will have no technology to help them. We can see the outlines of this in the frustrated question that many space-enthusiasts have asked of late: “Why could send men to the moon in the 70s, and yet can’t send men reliably into orbit today?” The answer is that we haven’t been pushing ourselves to go the distance. The Saturn V was developed by engineers who had practical experience pushing the boundary of our aerospace knowledge. They had designed rockets, rocket planes, and innovative supersonic airplanes before. They had practical experience building the things. The Saturn V wasn’t just a rocket – it was a culture that enabled it to exist. Today, the blueprints to build that rocket are in storage somewhere, the engineers are retired or deceased, and the companies that built the parts are out of business. Even the people who engineered the shuttle are spending their efforts holding the fleet together, and retiring. Most of the engineers in charge today have never had the opportunity to design and build a new rocket.

It ultimately doesn’t matter when we start – the technology won’t happen until we do. If we develop a moral paradigm now to put this off to a future generation, then as long as the paradigm persists, we will make no progress towards accomplishing the goal.

Basic Sizing of a Rocket

2005-12-13T10:54:00.000-08:00

Now – how big does your rocket have to be to get there? The following are pertinent equations for sizing a rocket:

For a rocket stage with a certain payload mass, propellant mass fraction, delta v, and engine Isp, the mass of the fuel, inert mass, and everything else falls into place. Tsiolkovsky’s (spelling on slide – I are engineer) rocket equation relates the mass ratio of the rocket stage to the amount of dv needed.

Isps (specific impulses) are typically around 300-420 sec for liquid propellants, and around 300 or below for solid propellants. Hydrogen/Oxygen – the best chemical propellant usable (there are better ones involving fluorine – but they produce poisonous gas as an exhaust!) has around 420 sec. 440 sec in vacuum with a good engine. The specific impulse, as a measurement, is defined as the total impulse (integral of thrust with time – the total change in momentum of the spacecraft) divided by the total weight of the propellant on earth. Neglecting atmospheric effects, it ends up being equal to the exhaust velocity * earth gravity. The faster your exhaust velocity is, the less fuel mass you need to make a certain change in momentum. (Thrust = mass flow rate * exhaust velocity, Impulse = mass expended * exhaust velocity).

Propellant Mass fraction is the ratio of fuel mass to the mass of the full stage – the payload. Chemical rocket stages have propellant mass fractions ranging from 0.7 to 0.9. It is a good idea to conservatively estimate 0.8, even though some rockets may achieve better performance when all is said and done. If you don’t end up having enough mass budgeted for your engines, you’ll have to iterate your calculations again.

For multi-stage rockets, one of the things that must be decided is what fraction of the total delta v each stage will take.

MRstage1 * MRstage2 * MRstage3 = exp((dv1/Isp1 + dv2/Isp2 + dv3/Isp3)/g0).

For stages of equal capability (equal Isp and propellant mass fraction), the lightest rocket is the one that has equal mass fractions (and equal fractions of total delta-v) for each stage.

The payload to total mass ratio helps round out the equations to find the total mass. Note – if the mass ratio is too low (dv too high) and the pmf is too great, it means the rocket stage can’t carry enough fuel to loft both the payload and the structural mass to the delta v. The payload fraction goes to zero, and then negative. This means you’ll have to stage your rocket further, or slim down on structural mass.

Example – you want to loft a 10000 kg payload to geostationary orbit. You decide to use a two stage rocket to accomplish this – both stages use hydrogen and oxygen propellant and a decent engine (420 sec Isp). Because you want your rocket to have minimized mass requirements, you equalize the dv required between stages.

Total mission dv = 9000+3580 = 12580 m/sec.
Dv for stage 2 = 6290 m/sec
Dv for stage 1 = 6290 m/sec
Propellant mass fraction for each stage = 0.8
Isp for each stage is 420 sec

The massfraction for each stage is 0.2169.
The payload fraction for each stage is 0.02116. This means that payload is only 2.1% of the weight of each stage!

The payload mass for the second stage is 10000 kg. The total mass of the first stage is 472546 kg. The fuel mass is 462546 kg. The inert mass is 92509 kg.

The payload mass for the first stage is the fully loaded mass of the second stage. The total mass of the first stage (payload included) is 22332000 kg. The fuel mass is 1717496000 kg. The inert mass is 4373000 kg.

So your total rocket mass is 22,332 tons. Umm, how realistic is this exactly? If you needed it to accelerate at 1.1 g forces (for takeoff purposes) you would need 241 MN of thrust. That equates to 129 space shuttle main engines. This is one gigantic rocket! I don’t think we would want to build anything this big. If you were constrained to a propellant mass fraction of 0.8, you would have to use more stages.

Let’s start over with a 3 stage rocket:

Dv for each stage = 4193 m/sec
Propellant mass fraction = 0.8
Isp = 420
MR = 0.361
Payload fraction = 0.20125

Notice that now your payload is 20% of the mass of each stage, and 8% of the total rocket mass. This is far better than the previous case, where your payload fraction was only 0.04%. Your rocket is going to end up being much smaller.

Stage 3:
Total Mass: 49689 kg
Fuel: 31,751 kg
Inert Mass: 7937 kg

Stage 2:
Total Mass: 246901 kg
Fuel: 157700 kg
Inert Mass: 39442 kg.

Stage 1:
Total Mass: 1,226,837 kg
Fuel: 783,949 kg
Inert Mass: 195,987 kg

A 1226 ton rocket is 20 times smaller than our previous 22332 ton rocket. To take off at 1.1 g forces, this rocket will only have to generate 13 MN of thrust. It would only take the equivalent of 7 SSMEs (52360 kg of engine there, leaving 143 tons left over for 1st stage structure).

This is still a sizeable rocket, but that is because 10 tons to GEO is a large payload for that sort of orbit.

Navigation in Spaaaaaace!

2005-12-13T09:37:00.000-08:00

How do you size a rocket for a mission? This is actually not very difficult to do if you know the pertinent equations. One of the first things you need to know is where you are going. This determines your delta v, the total change in velocity that your rocket makes as it accelerates the payload. To get into orbit, for example, you need to know how fast your payload ends up going.

Circular Orbits:

The velocity at which objects orbit a planet is determined by gravity and the altitude of the orbit. Orbits can be circular, elliptical, or hyperbolic (with a boundary case of a parabolic orbit). Hyperbolic orbits are escape trajectories, or trajectories which don’t involve capture by a planet. The orbital energy in these cases is greater than the escape energy of the system.

For circular orbits, if you use Newton’s gravity and balance it with centrifugal acceleration, you can solve for the velocity which an object has to attain to orbit.

For a low earth orbit (from about 100km to 1500 km), (100 km for this example) you rotate at a rate of 7840 m/sec. This is blazingly fast – one of the reasons why it takes so much fuel to get into orbit. But this isn’t the totality of the delta v which the rocket must expend. Part of it is drag loss. The rocket ascends through the atmosphere faster than any aircraft could hope to go, and drag wastes some of your propellant, usually around 1000 m/sec or so. Gravity loss is also an issue. If your rocket didn’t produce enough thrust to overcome gravity, it would go nowhere, but expend tons of propellant, hence effective delta v loss. Delta v losses for gravity are between 500m/sec and 1000 m/sec usually. They are equal to the effective gravitational acceleration on your rocket multiplied by the amount of time that it’s burning fuel to fight it.

Altogether, about 9000 m/sec delta v is required to get into low earth orbit.

Maneuvering in space:

To go beyond low earth orbit, additional burns must be made. Gravity and drag loss don’t factor in as much (for short burns) when you are beyond earth’s atmosphere and already in orbit. If you burn in your orbital direction, you will raise your orbital eccentricity, and enter an elliptical orbit. If you burn against your orbital direction, you will enter another elliptical orbit that oscillates between where you are and a lower altitude.

One of the simplest maneuvers to raise or lower your orbital altitude is the hohman transfer. For short burns, it is also the most fuel efficient trajectory for changing orbital altitude. It involves burning once to enter an elliptical transfer orbit. You then travel from the perigee of the elliptical transfer orbit to the apogee, where you burn again in the orbital direction to circularize your orbit. Then you are at a circular orbit with a higher altitude.

To transfer from low earth orbit to geosynchronous orbit – 35786 km – we first have to increment our velocity to get into the transfer ellipse. Our current orbital velocity is 7840 m/sec. The eccentricity of the transfer ellipse is 0.6934. The semi-major axis is 21132 km. The velocity at perigee needs to be 10201 m/sec. You have to burn to increment your orbital velocity by 2361 m/sec. Then you coast until you reach apogee, where your velocity is 1847 m/sec. The circular orbit velocity at a radius of 35786 km is 3336 m/sec. You have to burn again to increment your velocity by 1489 m/sec. The total delta v for this transfer is 3850 m/sec.

The program itself: Rocketcalc.cpp

2005-12-10T14:05:00.000-08:00

This post isn't working yet. I can't get the program to post in plain text. Does anyone know how to do that?

I'll get this program posted eventually. I've discovered a few more bugs, though, and need to make sure it isn't spitting out gibberish for more than 4 stage rockets.

I'll find a way to post the source file after I get back from my bug-hunting safari.

Rocket Sizing Software:

2005-12-10T13:45:00.000-08:00

The following is a description and some code for a piece of rocket sizing software that I'm programming. It takes a bunch of input variables that the user supplies and optimizes the dv distribution, and calculates the stage masses for a multi-stage rocket.

Have you ever wondered how large a rocket would have to be to launch a specific payload? What the effects of staging are? My C program answers some of these questions by providing a preliminary mass budget for a multi-stage rocket.

pmf (propellant mass fraction) = m_inert/m_fuel. A rocket is primarily a giant fuel tank. The amount of structure is roughly proportional to the amount of fuel. The propellant mass fraction is a number (usually between 0.7 and 0.9 for liquid rockets) that defines the ratio of fuel to (fuel+structure) mass. It neglects the payload. Any lighter than 0.9 and your rocket usually doesn't have enough structure to hold the fuel tank together, or withstand the forces of launch. In space vehicles may be able to get away with higher pmfs, but not launch vehicles. The pmf coupled with the limited Isp of chemical propulsion is also the primary reason why we don't do Single Stage to Orbit. Try it for a pmf of 0.8 and an Isp of 420, and see what you get.

The Isp (specific impulse) is the fuel efficiency of the engines for a rocket stage. Typical numbers are around 340 for kerosene/LOX engines and 420-440 for hydrogen/oxygen engines.

Any extra inert mass is included in the payload of each stage. Things like extra systems or structure can be directly added in to ensure that there is enough of a mass budget to attach them to the rocket.

The dv is the total change in velocity that the rocket can make. Missions in space are usually defined by the amount of dv necessary to perform them. Launching cargo into LEO typically requires 9000+ m/sec of dv. Going to the moon requires another 3200 m/sec or so. Landing on it or takeing off requires 1600 or so m/sec dv. Anyway, all of this stuff adds for your total mission.

My program was compiled as a command line executable with DevCPP. I don't know how to do makefiles. I'm an engineer, not a unix wizard.

Why send people?

2005-12-03T14:44:00.000-08:00

Human space exploration is the type of space exploration that I am most interested in. However, I don't think the primary purpose of human space "exploration" is exploration, as much as it is an attempt at colonization and expanding our capabilities to travel and live in outer space.

The probe people are probably right that it will usually require less mass to send machinery and instruments to a remote location than people. People radically complicate any space travel involved, with increased mass and specialized equipment required just to keep them alive. Furthermore, with modern computing technology, our probes can have a good degree of autonomy in what they do, and time delays for communicating become less of a problem. Probes do have drawbacks - they're usually limited to doing only the types of exploration that they're designed for, they're physically clumsy and can run into obstacles that a human being would just step over or shoulder aside, and they can only deal with problems that the programmers anticipate. However, they have succeeded in getting the basic exploration of the inner solar system done.

If a human being is going to another planet, odds are that a probe has gotten there first, mapped the surface, located deposits of useful materials such as ice and various metals. On mars, our surface rovers are drilling samples from rocks near to their landing area at fractions of the payload mass required to send people. If we only wanted to explore mars, we could send a spacecraft with equivalent payload absolutely jam-packed with sensors, bus sized rovers and robots, drill rigs, ect, all without the life support, water, and living space that people require.

But then again, why are we exploring space? Exploring extremely distant galaxies and other stellar objects gives us a picture of the universe, how it came about, ect, satisfies some curiosity and hones our physics. Exploring the inner solar system holds the long-shot chance of discovering life that may have developed independently of Earth based life, and thus dramatically raise the guessed-at chances of life existing in other star-systems, as well as giving microbiologists something to study. However, I think the main reason we explore space is to see if there's something out there that we can use, to see if there's somewhere new to expand our human presence to. When we began having inklings that the other planets were worlds just like the earth, getting people there was one of the first things to come to mind, no matter how impossible it seemed at the time.

Why bother knowing whether or not the moon has ice? So that when we start building bases there we can drink the water and grow our food (unfortunately the moon doesn't have a whole lot of hydrogen or ice). Why try to determine the effects of zero gravity on frogs? So that we know what sorts of precautions we have to take when we send people on interplanetary trips.

Slow Posting

2005-11-28T06:03:00.000-08:00

I may not post much for the next few days. Holidays are over, and exams are piling up.

The Cassini-Huygens Mission

2005-11-18T17:01:00.000-08:00

The Cassini mission is a mission launched to Saturn on Oct 15 1997, and entered orbit in the Saturn system on June 30 2004. Its purpose is to study the planet, moons, and rings of the Saturn system.

Out of Respect for Copyrights - I've posted links to pictures instead of the linked images themselves.

The Cassini Probe

Its launch generated a lot of hype back in the 1990's. It carried a small nuclear battery, called a radio-isotope thermoelectric generator or RTG, which provided power and heat to the probe. Deep space probes operating far from the sun cannot get solar energy to run their instruments, and conventional batteries don't last years at a time, so RTGs are usually employed. This RTG caught the attention of the enviro-mental community, which latched onto the fact that it used a nuclear material (2kg of plutonium) to generate heat to run the device. The screaming protest was spectacular. They were prophesizing that if it were to crash over the gulf of Mexico, hundreds of thousands of people could die from nuclear contamination, and it would wipe out sea life in the area (2 kg of plutonium!).
Info about RTGs.
Of course, such concerns were absurd, first of all because of the extremely low amount of the nuclear fuel (think about it: if plutonium is that dangerous, why do we insist on weaponizing it and building atomic bombs at all? Why not just spray parts-per-billion powder over a country?), and second of all, because it is designed to break up in the upper atmosphere to disperse harmlessly. It's also an alpha emitter.

In any case, despite the hoopla, and protestors in Darth Vader masks, the mission launched successfully, did a swing-by of Venus, then Earth, then Venus again. This fortuitous and intricate trajectory, and its associated launch window enabled the probe to make the voyage, boosting its velocity enough to send it on a trajectory for Saturn.

The Interplanetary Trajectory

When the probe arrived in the Saturn system, it detached the Huygens lander on 24 December 2004. The Huygens lander landed on Titan on 14 January 2005. The probe successfully took and transmitted pictures of the surface, atmospheric and wind data, and even sounds from the surface of the moon.

Titan is a moon of Saturn, with a radius of 2580km (for comparison, our moon has a radius of 1700km and Mars has a radius of 3400km). When Voyager I first flew by this moon in 1980, it could not penetrate the hazy atmosphere to detect anything about the surface. The atmosphere of Titan is a dense smoggy layer of methane. Titan can maintain an atmosphere this dense because of its very low temperature, being far from the sun in the outer solar system.

A Comparison of the Sizes of the various Moons.

When Huygens landed, it found that Titan has a surface sculpted by liquid methane and other simple hydrocarbons. The planet looks superficially Earthlike, at least in black and white, with river deltas and lakes. But the rivers and lakes are methane and hydrocarbons, and the rocks are water-ice and nitrogen. Titan's surface has a temperature of about 94K (-290F).

Titan's sea from Huygens as it descends.

Color Image of Titan's Surface

Conquering the Solar System

2005-11-18T12:51:00.000-08:00

Conquering the Solar System is going to be part of the theme of this blog, hence the title. I do believe that it is a goal acheivable with realistic technology, a good portion of which we already have. I think that it is a reasonable (in the sense that it is doable) goal to begin in our lifetimes, and to continue through next few generations: to colonize the solar system and set up a space-faring civilization.

But first, an interlude. I'll be posting about some different topics.

The Real Prospects for Interstellar Travel (Part II)

2005-11-18T12:43:00.000-08:00

Basically, conventional rockets won’t be able to get us up to light speed. There are other ways to work the problem, however:

1. Don’t go so fast: Build a generation-ship. Generation ships are ships that only accelerate up to a small fraction of the speed of light, and then coast sloooowly towards another star system. If you had that fusion propulsion thing worked out, and only wanted to go 5% the speed of light, you could get mass ratios of 148 or so. A base built on a comet that uses its water as a fuel source might be a potential example of one of these. Of course, they’re called generation ships, because they would have to accommodate multiple generations of astronauts! A trip to Alpha Centauri no longer takes 5 years, but 100!

2. Bussard Ramjet – It might be possible to scoop fuel from interstellar space. A bussard ramjet works by accelerating conventionally up to some fraction of the speed of light, where it then turns on a giant magnetic scoop. This creates a huge magnetic field in front of the vehicle, several tens to hundreds of miles wide. Through some sort of ionizing laser or radio pulse, the ramjet ionizes the interstellar hydrogen in front of it (if it isn’t already ionized) and draws it into the vehicle, where it is fusioned and expelled out the back, faster than it was drawn in. In order to work, the fuel must be expelled at a greater velocity than it is taken in. The interstellar medium is very sparse, however, and so this vehicle must attain a good running start.

3. Don’t shoot the fuel from the spaceship – shoot it to the spaceship! If you fire the fuel at the spaceship in the form of a neutral particle beam, you don’t have to keep it onboard, or use an onboard power source to accelerate it. The fuel can be accelerated from a gun located back in the home star-system. The fuel exhaust velocity can be however high you want it to be, due to the fact that you can put any amount of external energy into it as it leaves the accelerator gun. The vehicle would grab the fuel by ionizing it and magnetically reacting against it, as it comes in, thus gaining velocity. The vehicle’s design could then focus on bearing and supporting payload and astronauts, rather than packing in fuel energy. The amount of fuel required to accelerate the spacecraft no longer depends exponentially on the speed you want to achieve, but rather in a different non-linear way, so that the limitations that rockets have are no longer relevant.

The governing differential equation is dv/dt = mdot(ve-v)/m, assuming complete deceleration of the particle beam by the spacecraft. Mdot is the rate of mass expulsion at the solar system. Ve is the velocity of the particle beam. M, and v are mass and velocity of the spacecraft. This doesn’t take relativity into account.

***

Interstellar travel is difficult to accomplish, and requires a lot of technology that we don’t have yet. Does this mean we can’t do it? No, I don’t think that it does. For one thing, even if we’re limited to the technology that we know of today, we can still, just barely, make these sorts of voyages. And there’s no telling what we will discover, or what refinements to our technology will be made in 1000, 2000, 10,000 years of human history. There’s no way that the ancient Chinese could have made it into orbit or to the moon, even though they were the inventors of the rocket. There’s no reason to suspect that we’ve made the last inventions or discoveries in science or technology, or that we’re converging on the “end of human knowledge”, as some would like to believe.

But I also don’t expect it to happen in our lifetime, or our children’s lifetimes. It will take a long hard climb up in our space travel capabilities. Before we start launching spacecraft to the stars, we first have to be capable of conquering the solar system. We have to learn to crawl, before we can run. We have to be able to make 3 year voyages, 5 year voyages, 10, ect before we can start zipping off to the stars in 20+ years trips. We have to be able to construct decent bases and stations in space before we can start constructing giant accelerator guns to propel starships. We have to be able to make 30 kps dv missions before we can make 3*10^5 kps dv missions. So we have a long way to go, and I think that space travel in our lifetimes, in this generation, and those immediately after ours will have more to do with conquering the solar system than with zipping off to other star systems.

The Real Prospects for Interstellar Travel (Part I)

2005-11-18T12:41:00.000-08:00

I’ll talk a bit about the prospects for interstellar travel: While science fiction is filled with tales of predominantly interstellar exploits, and ships that zip from one star system to another like it was a piece of cake, realistically, based on the physics that we know right now, interstellar travel is a difficult proposition, even theoretically.

For one thing, unless some savant finds a way around the speed of light limit, and overthrows the limitations of mass, energy, and momentum allowing us to take such shortcuts around that limit, we are confined to travel at or below the speed of light. The nearest star, Alpha Centauri is 4.3 LY away. Other nearby stars are Barnard’s Star at 5.94 LY away, Lalande 21185 is 8.315 LY away. Sirius at 8.6 LY away. Procyon at 11LY, ect. If all it meant was to accelerate up to light speed, then journey for 5-20 years to reach the new star system, such a voyage would hardly be an insurmountable task. Difficult, yes, time consuming, yes, but quite doable. Foreseeable advances in technology, such as the possibilities of inducing hibernation, or of indefinitely lengthening lifespan through some genetic or medical technology (in which case we might not care as much about the duration of such a trip) could help ease the voyage. Or we could suck it up and deal with the isolation.

However, the critical assumption here is that we will be able to easily accelerate our spacecraft up to near light speed. This is a task of extraordinary magnitude, when viewed as a problem involving conventional rocketry.

The mass that a rocket has in fuel is related to the total amount of change in it’s own velocity (or delta v) that it can make, and to the exhaust velocity of the propellant. In idealized cases, such as gravity free, drag free flight, this is a good measure of how far and fast a given spacecraft can go.

Tsiolkovsky’s equation.
Mpayload/mrocket = exp(-delta v/exhaust velocity)

Our everyday chemical rockets have exhaust velocities on the order of 4000 m/sec. They can achieve delta vs of about 9000 m/sec – 11000 m/sec (with the use of staging). If we were to look at the mass ratio required to get from 0 up to the speed of light, delta v would be 3E8 m/sec.

Ln(Mrocket/Mpayload) = 3E8/4000 = 75000. In other words the mass of the rocket would be 10^32572 greater than the mass of the payload. In other words – no starship for you, smack! It’s clearly a ridiculous number. Chemical propulsion won’t cut it.

Nuclear fission propulsion, such as nuclear thermal propulsion can improve this number a bit. Exhaust velocities of 12,000 m/sec (for solid-core nuclear thermal with oxygen augmentation), 40,000 m/sec (for nuclear electric propulsion), 100,000 m/sec (for more exotic and theoretical forms) are possible. These would yield mass ratios of 10^10000, 10^3257, and 10^1302 respectively. Still, not anywhere near good enough.

Fusion propulsion, through reaction and expansion through a magnetic nozzle, promises very high Isps (Isp is effective exhaust velocity/9.8m/sec^2, and is a common measure of rocket fuel efficiency). Estimates vary wildly because we don’t have the technology yet to produce energy from a fusion reaction. Isps of 300,000 sec are given for IEC fusion at http://www.projectrho.com/rocket/. Mass ratio: 10^43. 10^43 is still problematic, due to the fact that you would have to have a tank for all that hydrogen. The tank must be less than 43 orders of magnitude lighter than the hydrogen fuel.

Anti-matter propulsion is the ultimate fuel source for a rocket. It packs the maximum possible energy (hence impulse) per unit of fuel. When anti-electrons react with electrons, only gamma rays and neutrinos are left over. But realistic anti-matter propulsion needs a way to direct the product particles out the back of the spacecraft, hence they need to be charged. Anti-proton-nucleus reactions do this much better. However, to do this, you need a large mass of anti-matter. Anti-matter is currently produced at great expense in particle accelerators, or trickles in very slowly in the form of some cosmic ray types. Anti-matter would get you mass ratios as small as 20. This is quite manageable, but for a payload of 1000 tons, you would need 19000 tons of an even matter/anti-matter mix!

Basically, conventional rockets won’t be able to get us up to light speed. There are other ways to work the problem, however:

The Absurdity of a Galactic Empire

2005-11-17T18:53:00.000-08:00

One of the things that has always made me laugh and shake my head was the abundance of galactic empires in science fiction. In many science fiction movies, from the Star Wars series, to the new Serenity movie, as well as in books like Asimov’s Foundation series, there are fictional nations that lay claim (or at least claim to lay claim) to all or most of the entire galaxy. With names like “The Galactic Empire”, or “The Universe Alliance”, these organizations manage to control (and even to oppress and enslave) hundreds of planets across interstellar distances. Controlling a single planet is a feat in and of itself (hasn’t been done yet), expecting two or more to bend knee and settle into cultural uniformity is ridiculous. The difficulty of traveling over interstellar distances isn’t even the primary problem, though I’ll discuss that in a section following this one.

To paraphrase Arthur C. Clarke, even if we someday have a technology that allows us to travel between star systems as easily as dialing a telephone, we still have to face the fact that the galaxy has 100 billion star systems. Even though man may one day manage to colonize the entire thing, after millennia of effort and unrelenting expansion, we could never be said to have truly conquered or tamed it any more than the ants have conquered and tamed the Earth. The galaxy is far too large, let alone the universe.

So, it’s far too large to control or ever truly conquer. If we had the capacity to construct a starship for every family on the face of earth and launch them off each to their own star system tomorrow (6.5 billion people/ about 5 people/family) = 130 million colony ships. If we radiate the population of the earth away in such a manner, and “colonize”, if we can call it that, as many systems as we could with just 1 family apiece, we would still only have set foot on less than 1% of the entire galaxy!!

So, as far as galactic empires go, the sheer size of the galaxy renders our human notions of empire and domination absurd.

The Known Extent of the Universe, Part II

2005-11-17T11:49:00.000-08:00

The distances to other galaxies cannot be measured the way we measure most other distances. Parallax won’t work for any but the closest star systems. You cannot reflect signals off even the closest stars, as the travel time would be years. So to measure the distances to other galaxies, a different method is used.

There is a class of star called a Cepheid Variable Star, an enormously bright type of star with a periodic fluctuation in the intensity of its output. The period of these stars happens to be related to their power by a known function. See

Cepheid Variable Stars

. By measuring the apparent magnitude of these stars in other galaxies, and correlating them to the output that we expect, we can determine the vast distances between the galaxies.

An interesting phenomenon was discovered by an astronomer named Slipher: almost every galaxy in the sky is red shifted with respect to us – the light reaching us from these galaxies is redder than it should be – their spectra are shifted. (Astronomy: A beginner’s guide to the universe, pg 438, Chaisson McMillan). Not only is this the case, but the red shift is tightly correlated with the distance from our own galaxy. Red shifts and blue shifts are indicators of radial speed under relativity. Great enough speeds tend to increase or decrease the energy of the photons emitted by an object with respect to the observers. The red shift, interpreted as a measure of relative velocity, gives a surprising result: Almost every galaxy is moving away from us at a speed proportional to their distance from us: recessional velocity = H0 x distance. This doesn’t just go for our own galaxy (this phenomena does not require us to be at the center of the universe), but every galaxy is moving away from every other galaxy at a distance proportional rate. Hubble’s constant = 75 km/sec/Mpc (Mpc is a megaparsec, or 3.3*10^6 LY).

This startling discovery leads to the big bang theory of the origin of the universe – if every galaxy is moving away from every other galaxy at a speed proportional to distance, then it follows that at one time in the distant past, the universe was packed much closer together.

There are several modes to the expansion of the universe which are possible – we have only one space-time cross section which we are capable of observing (a light-cone extending backwards in space and time 1 year for every lightyear). These different modes of expansion are primarily dependent on a number called omega which is a ratio relating to the density of matter and energy in space.

Omega < 1 would yield a universe that should, according to our understanding of general relativity and gravity, expand indefinitely and with ever increasing speed, leading to an eventual heat death.

Omega > 1 would yield a “closed universe” which would be bounded in space as well as in time. The space would eventually curve back in on itself, and time would as well, leading the universe to accelerate back together in a “big crunch”. The concept of a bounded finite universe that will end someday has enjoyed tremendous popularity, though I have no idea why. The possibility depresses me. For philosophical reasons of my own, I would be extremely disappointed if the universe should turn out to be finite in either space or time.

Omega = 1 would yield a universe that would expand at an exponentially decaying rate. Eventually it would stabilize, and continue to exist indefinitely, neither exploding outwards into a cold heat death, or collapsing back in on itself.

Based on Hubble expansion alone, any of these scenarios is possible. Based on information from the cosmic microwave background radiation (radiation from the very early universe), astronomers believe that omega is, against all probability, extremely close, perhaps equal to 1. If this is the case, then the universe should have a spatial geometry that is globally “flat”, or which doesn’t curve back in on itself, and should therefore be literally infinite in extent space-wise (we can’t see all of it yet, because when we look, we look along a light cone, and eventually run into the big bang).

But all of the mass that we see in the universe today couldn’t possibly account for the mass and energy density required to make omega = 1. Going off of the visible mass, our universe should have a much lower omega, and should be in the process of exploding violently outwards.

This, along with certain other oddities in the rotation rates of galaxies (which are larger than they should be based on our estimates of the mass of stars), has led astronomers to the idea that there might be “dark matter” in the universe. Dark matter is a name for mass that we haven’t found yet, or cannot account for, in terms of the gravitational behavior of objects on a large scale. It could either take the form of matter which we have no means of detecting, or it could be some sort of correction term that is required in our understanding of gravity over large distances, but to make our models of the universe work, this missing mass has to be present. Some have wanted to replace the big bang theory with something else on account of this hole, but to date nothing else explains the Hubble red shift as well as the big bang theory has.

***

In any case, it is quite possible that the universe is literally infinite in extent. Even if it is not literally infinite (in which case, I’d be somewhat disappointed), it is still for all intents and purposes practically infinite in extent, of which we can see 14.7 billion light-years, tens of billions of galaxies, each of which have hundreds of billions of stars.

The Known Extent of the Universe

2005-11-16T19:17:00.000-08:00

Since this blog's theme is going to be my long time interest in all things related to space exploration, I thought I would start out with a review of where we are in space, and the structure of the universe. Most space enthusiasts probably already know all this stuff, but novices might find it interesting:

Everyone knows we are on Earth, orbiting the sun along with 10+/-2 planets (depending on the mood of the astronomy community - pluto/sedna/charon/qauoar regularly change designation from planet to comet and back!). The other stars in the sky are indeed other suns, with planetary systems of their own. We are beginning to detect planets in orbit around other star systems, though our ability to detect them is still coarse and limited to very large planets. What perhaps most people don't have a very good grasp of is the vast extent of the universe. The universe is enormous! It is impossible to convey with mere words how huge it is, but perhaps hurling numbers at the problem can help:

Our star exists in one spiral arm, off center of our galaxy, which is our local pie shaped group of stars. The milky way itself has a radius of about 50000LY, our star being 30000LY from the center. The galaxy contains over 100 billon stars. That's just our galaxy though.

At one time not very long ago (70 or so years) it was thought that our galaxy was the universe. But the galactic scale is only the beginning of what is observable. We discovered that some of the off-plane nebulae were actually extraordinarily distant conglomerations of stars, and that these objects were like the disk which our own star inhabited. The observable universe extends out quite a ways, and currently is jam-packed with about 40 billion galaxies. (Astronomy: A beginner’s guide to the universe, Chaisson McMillan, pg 419). While stars are very far from each other on the scale of planetary systems, galaxies, on a galactic scale, are about as close to each other as plates on a dinner table.

A few amazing Hubble pictures as an interlude, and to drive the point home:

Image 1

Image 2: The Tadpole Galaxy: One of my favorite desktop backgrounds

Image 3

These are from the Hubble deep field images. They are from minute areas of the sky exposed over hours (the photons come in very slowly from such distances).

To be continued: More to come on this topic.

Exams! Exaaaams! Aahhhggg!

2005-11-15T18:53:00.000-08:00

My Econ exam is now done. I only have the 364 controls exam and an aero project meeting left before I'll have the time to begin seriously posting.

I wonder how many people wander by a mostly empty blog like this? Comment if you happen to view this post please.

Solar Empire Blog

2005-11-14T13:16:00.000-08:00

This is my first post on my first blog. If you haven't guessed from the title, I'm a space nut. This is just to test the page and to get things started.

BTW - To anyone who happens by this blog, I'm also an engineering student and have no time to be doing this. So I'm not going to post very frequently.