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Georgetown Space Policy Panel Report
More-than-occasional commenter Chuck Divine has a more extensive first-hand report from the panel discussion on space policy in Georgetown a few weeks ago.
On February 17, 2004, the Georgetown University Law Center hosted a panel discussion on the future of the U.S. space program. The panel consisted of Jim Muncy (Polispace), Col. Rick Searfoss (former astronaut), Edward L. Hudgins (Objectivist Center) and Robert Park (physicist and space critic). James Dunstan served as moderator.Posted by Rand Simberg at March 02, 2004 09:33 PM
I see another mention of Hudgins comparing an undersea robot to a "space pod." Does anybody know the specifics of this comparison? He has made it many times, but I think it is a deeply flawed comparison. I want to know what specific proposals he is comparing.Posted by Dwayne A. Day at March 3, 2004 08:30 AM
It's probably based on a piece that Bill Haynes wrote back in the eighties, in which he compared Deep Rover to the planned NASA Orbital Maneuvering Vehicle, and noted that for equivalent functionality in a harsh environment (extremely high pressure, corrosive salt water), there were about three orders of magnitude difference in cost.Posted by Rand Simberg at March 3, 2004 08:40 AM
I will have to look at that. The analogy just does not hold up well for me. For starters, the environments are not similar. For instance, the temperature range for a spacecraft is huge, but not so for an undersea vehicle. A spacecraft also needs its own power supply, whereas an undersea vehicle can use several options--in this case probably rechargeable batteries. And weight is not really going to be a concern for the undersea vehicle, at least not as big a concern.
In addition, the responses to these differences are also going to be quite different. Undersea vehicles can solve a lot of problems, for instance, by simply adding weight--more steel, more batteries, heavier systems. Weight increases, even quite big ones, do not have substantial cost penalties. That is not true for spacecraft.
I think that a better comparison would be between equivalent spacecraft, rather than things that operate in entirely different environments and engineering fields.Posted by Dwayne A. Day at March 3, 2004 01:17 PM
Probably the biggest difference is the weight issue (which is a consequence of needlessly high launch costs). But the marine environment is extremely harsh in its own ways.
It's not a perfect comparison, and certainly a space-space one would be better, but none (yet) exists. Nonetheless, it's a question worth asking, and a comparison worth at least thinking about, in terms of what the real cost drivers are. There's abundant evidence that at least an order of magnitude of the difference is a function of government (and particularly NASA) procurement practices.Posted by Rand Simberg at March 3, 2004 01:25 PM
I don?t see any mention of a ?space pod.? Are you referring to this - ?Hudgins compared the cost of a deep sea rover with the Mars rover??
I consider the deep ocean environment to be far more hostile than the Mars surface or the space environment through most of the solar system (exceptions for Jupiter?s belts, near the sun, etc.) Frankly, I just don?t see what is supposed to be so harsh about the Mars environment for a machine.
The big problem with Mars (and space in general) seems to be coping with massive thermal variations, while being stuck with only radiative forms of heat management. (At least for long mission durations or where volatile resupply is not an option - sublimation was employed extensively on Apollo). It's those thermal variations that will likely kill the Mars Rovers, once the power supplies are too low to effectivily regulate the internal temperature. Thermal variation were also what did in Magellan.
The other big cost driver is radiation hardening key electronics from solar protons.
Both of these are not factors in the deep sea environment.
I will add a third - I expect positive internal pressures are structurally a lot harder to design for than negative internal pressure - most materials are stronger in compression than tension.Posted by Duncan Young at March 4, 2004 02:10 AM
The problems of themal variations and rad hardening are very bad with small vehicles, but they are no big deal with large vehicles.
And structures with positive internal pressure are much easier to design than with negative internal pressure.
A pressure vessel that has 1 atmosphere internal pressure is quite light and simple, while a vacuum chamber for the same pressure difference will need very thick walls or reinforcements to avoid buckling.
The best way to get cheaper and more rugged spacecraft is to throw mass at them. This is not as easy as it sounds, since it requires a fundamental change in mindset for an industry that has tried to save weight for the last 30 years. But even with todays launchers you could save a lot of money by making spacecraft heavier.Posted by Rüdiger Klaehn at March 4, 2004 04:35 AM
Um, I'm not a structural engineer, but light bulbs seem to do just fine. I haven't done the test but I would hesitate to pressurize one to net positive 1 atmosphere.
But even with todays launchers you could save a lot of money by making spacecraft heavier.
I dont see how dropping the payload in the Atlantic as opposed to putting it in orbit saves you money. Or maybe I have missed your point.
I might be sticking my neck out in an area where I am not qualified, so I am going to phrase some of this as a question.
It seems that heavier vessels would deal with some of the problems associated with long term human space travel. Thicker walls deal with, or at least alleviate, the radiation problem. Thicker walls also alleviate the thermal variation issue. I recognize that there are massive terrestrial launch costs here, but would lunar processing facilities be able to deal with this type of vehicle? What I am suggesting is that perhaps some of the issues associated with manned space presence are caused by our terrestrial launch base. If we dont have to worry about launching all the materials involved, then mass becomes much less of a limiting factor. While the undersea view seems flawed in comparison with current design parameters, perhaps this will change as our launch parameters change. Would it be beneficial to use lunar regolith derived concrete or metals as a shell for exploration vessels? This obviously doesnt deal with the problems associated with landing modules and robotic probes, but it could be useful in the area of orbital/interplanetary/ activities. You also would have to deal with guiding all that mass, but it could have application as the base station from which more mobile craft are deployed.
As for the application to the current launch reality, massive craft cant be put up in one launch, but multiple launches can work wonders. We need to develop standardized orbit linkages anyway for mid to long term station development. Again, I am only suggesting this in order to ensure that more than one approach to building is considered. Mass can be our friend (once it gets out of the gravity well at least).Posted by Nathan Horsley at March 4, 2004 06:16 AM
Um, I'm not a structural engineer
With all due respect, Duncan, it shows...
Most materials are much stronger in tension than in compression. Masonry is the exception. Building a negative pressure vessel is much more difficult (and will be much heavier) than a positive one from any metal (or even glass).
And we generally avoid building positive pressure vessels from glass not because it's not sufficiently strong, but because its failure mode is sudden and catastrophic.Posted by Rand Simberg at March 4, 2004 09:01 AM
Thanks for posting my report.
The comments so far intrigue me. They all seem to be triggered by Hudgins' deep sea vs. space comparison -- even Dwayne Day's.
What did people think about the rest of the report? While there, I thought the most interesting parts were Searfoss' and Muncy's.
The panel wasn't all that much about hardware per se.Posted by Chuck Divine at March 4, 2004 11:15 AM
It was a great report. I tended to agree with Hudgins? positions, though not completely. They should continue with research, but ?air? should be included along with ?space.? Things I?d like to see ? no more whole spacecraft or spaceplane designs dictated by NASA, no more whole spacecraft design programs. Their focus should be reliability and cost, new technology should be used to support that, but shouldn?t be a goal in itself. Research on better pieces (reliable engines, tougher heat shielding). Logical development programs: If you can get to space ten times cheaper and reliably, a space station can be much bigger, cheaper or both. And so on.
As for the comments, don?t knock ?em, it shows people are reading, and care. And, well . . . Dwayne started the fight! (heh)Posted by VR at March 4, 2004 01:53 PM
Yeah, I started the fight--with a question. I still have not seen a satisfactory answer. And it is essentially besides the point to say "you can make space cheaper by building stuff bigger, as long as you've lowered the launch costs." I wasn't asking about hypothetical futures, but about a real analogy existing in the present time (when increasing payload mass on a spacecraft has tremendous impacts and costs).
As for the overall comments on the panel discussion, I didn't comment on the review of the other speakers because I did not think they were notable. But Hudgins seems to have made a few claims that I find questionable. The other one was this: "The shuttle and ISS should be spun off ASAP." I would like to know how that can be done.
Well, I didn't really think of it as a fight so much as a discussion.
There are many factors that go into the high cost of space hardware, as I've often discussed here (e.g., government procurement procedures, the elevation of pork over function, overspecification, and the high cost of getting things into space). The main point is that space hardware doesn't have to be intrinsically expensive just because it's space hardware.
Private development will probably mitigate the institutional causes of high cost, and (dramtically) lower launch costs will eliminate those high costs that are due to the perceived need for weight reduction. But this will all remain speculation until we get private entities doing things in space with reduced launch costs. The examples provided here and in the next post simply provide a hint that this may be the case, not indisputable proof.Posted by Rand Simberg at March 4, 2004 03:31 PM
And my comment was a joke. It was intended to be interpreted as ?Nah, Nah, He started it!? silliness (the ?heh? was a hint).
Rand, that pretty sums up my thoughts on the subject. The process is the real issue.
I am NOT putting down the current Mars rovers, but shocking as it sounds, you can find very harsh environments on this planet, and we manage to deal with those without so much cost. Deep ocean is one of the worst. THAT is the point of comparison for the rovers.
Regarding some of the earlier comments - the Apollo LM had a pressure shell of aluminum about the thickness of heavy-duty foil. Unmanned craft generally don?t even bother with a pressure shell. For deep ocean, there have to be moving parts that will operate at pressures that can reach more than 1000 times atmospheric pressure, water that is cold enough to gel many lubricants, pressure enough to change the way chemicals work. High pressure water will rush in microscopic abrasions, salt will not react well with electricity. How is that easier than Mars? Regular hardware deals with temperature swings in the hundreds of degrees every day, and can last decades. Mars radiation is trivial compared to Jupiter?s rad belts, and we designed for that already. Mars has an environment we know how to deal with, and it shouldn?t be THAT expensive.
Dwayne, if Rand didn?t make it clear enough, lower launch cost means far more than just meaning you can build heavier probes. It changes the entire equation ? you can try more things, build more, use less sophisticated techniques and you still come out ahead. The current throw away launch process is a big part of the problem.Posted by VR at March 4, 2004 05:07 PM
VR, I am _not_ disputing that lower launch costs could do those things. I am saying that the space probe=underwater probe (and the particular one that Hudgins cites) is a Bad Analogy.
I am being nitpicky or whatever you want to call it, but bad analogies are bad analogies. You cannot _prove_ that lower launch costs are magical solutions by using an inappropriate analogy.Posted by Dwayne A. Day at March 4, 2004 05:32 PM
I wasn't knocking the comments at all. I am glad I was able to offer a decent report of the event and that people appreciated it. I was just making an observation about the discussion. I apologize to anyone who thought I was criticizing them.Posted by Chuck Divine at March 5, 2004 06:02 AM
Didn't think you were criticizing, Chuck. I just suspected that you didn't realize that it is common for comments to focus on one point, but that it is usually good there ARE comments because it shows people were reading. One of the biggest problems with written conversations is that they don't carry the emotions we hear in voices or see on faces, so it is very easy to misinterpret a writer's intention. That's one reason there are so many Usenet/Internet flame wars. I wasn't annoyed by ANYTHING in this thread, but I did enjoy the discussion.Posted by VR at March 5, 2004 02:50 PM
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