And now to distract you from my typograpical errors, the Hubble Deep Field:
Posted on 02/08/2003 12:05:20 PM PST by Liberal Classic
A friend at NASA's Marshall Space flight Center in Huntsville, Alabama told me today that all his engineer friends were working on their resumes. After the Challenger disaster, NASA dithered for 2.5 years before using the shuttle again. How long this time?
Quite probably, a year--if ever. This second wreck calls into question the entire shuttle program. Voices already are calling for a wholly new approach. The shuttle has the worst safety record of any launch vehicle, and is the most expensive, costing half a billion dollars per mission.
And we now contemplate a war in Iraq that depends on our technical prowess. I doubt that Americans will be moved to doubt our military, just because an advanced spacecraft fell out of a clear blue sky. We are tougher than we may look--and more resolute. The country is reasonably united, and yet again the president has responded with the right sense of gravity. He does disaster well.
Still, it is a good time to reassess. Early results from the telemetry and the huge debris field suggest that the thermal tiles failed. One amateur observer saw something blowing off the shuttle as it passed over California, possibly red-hot tiles. We know that a piece of foam blew off the fuel tanks at launch, striking the shuttle's left wing, a location that seems implicated in the heating spike that the telemetry recorded just before the craft began to slew and tumble.
Reentry is a tricky negotiation between gravity and aerodynamics. Controlling descent angle is important to reduce mechanical and thermal stress on the spacecraft, and an error in the on-board computers can allow the angle to get so steep that the craft breaks apart. (Multiple computers should reduce the risk, but that has not saved computer-run aircraft like the SAAB 39 Gripen from the occasional crash.)
Whatever the fault, tiles or computers or human error, the crash occurred at what many engineers thought was the most dangerous portion of a shuttle's flight. This is not a fluke; the system was vulnerable, and it failed yet again.
Perhaps the only good thing about this disaster is that it will prompt NASA to rethink the design of manned spacecraft from first principles. Foremost is that the more complex a spacecraft is, the more things can go wrong.
The safest manned descent module was also the simplest: the Soviet "sharik" descent capsule, which was used by Vostok and Voskhod craft, and also in many unmanned missions since. It was just a sphere with the center of gravity on the side with the thickest ablative thermal shielding, so it was self-stabilizing. Even if the retrorockets failed to separate, it could re-enter safely. Simple ballistic craft that do not fly are also (relatively) simple.
With a spaceplane like the shuttle, however, you are not only committed to a complex shape, you are also committed to using brittle ceramic materials for thermal shielding. The first item on NASA's agenda will be to revisit the tiles issue.
The ceramic tiles not only make overhaul very time-consuming and expensive - specialists affix each tile by hand, managing to do a few per day, and there are thousands - they are also literally impossible to check for inner defects. Unlike metal components, you cannot test them for small cracks that may cause failure.
One way around this is to use many small ceramic tiles, so the spacecraft can survive losing individual tiles. But if several adjacent tiles are lost, it will cause catastrophic failure during reentry. Maybe that happened; it is consistent with what we know now (or are likely to know for several months).
A second line of defense is to have the crew in a detachable unit that can land safely. This would be straightforward in a ballistic craft, but with an aerodynamic spaceplane it is difficult to squeeze such a unit into the nose. On the B-58 bomber the crew had small individual pods that enabled them to eject safely at supersonic speeds, but the weight penalty ruled out this option for the shuttle.
Ideally, you need a descent module that can take a lot of punishment. But a big spaceplane would get impossibly heavy if it was stressed for this. This is another argument for small sixties-era crew capsules.
Ironically, the Soviet "Buran" shuttle could lift loads to orbit without any crew at all, and might make a viable alternative to the U.S. shuttle. But the only remaining craft got badly damaged when a corroded hangar roof fell down on it last year - a symbol of the Russian program's decay.
The safest manned spacecraft built was also among the cheapest and simplest. The lunar lander used pressurized tanks, eliminating the need for turbo pumps, and the fuel and oxidizer self-ignited when mixed, making the engine very reliable.
NASA considered mass-producing similar, simple rockets in the sixties as an option to make space flight cheaper. Political considerations favored the more spectacular spaceplane solution. To date, this decision has killed two shuttle crews and cost billions.
In the end, the next months will try NASA as never before. It has tried to convince its public that going into space is safe, when it is not. Once is an accident, twice is a defect.
The shuttle's justification these days has been its role in supporting a space station that now does little science. The station runs with the minimum crew of three, to save money while forgetting science. The Russian Soyez vehicle could cycle crews and probably will be used to bring down the three up there now.
The station program can limp along for a few years with two flights a year, to cycle crews every half year and not abandon the station entirely. A Russian Proton rocket can continue to boost the station up as its orbit decays from atmospheric friction, as we now do routinely.
This can go on until NASA can decide what to do. Its habit is not to be truly decisive, but now its back is to the wall. It must confront the big question:
What is the American destiny in space? The station is not a destination; it is a tool. But for what?
NASA has played up the station as "a stepping-stone to the planets" - but it cannot perform the two experiments we know must be done before any manned ventures beyond Low Earth Orbit begin.
These are, first, development of a true closed biosphere in low or zero gravity. The station recycles only urine; otherwise, it is camping in space, not truly living there.
Second, we must develop centrifugal gravity. Decades of trials show clearly that zero-g is very bad for us. The Russians who set the endurance records in space have never fully recovered. Going to Mars demands that crews arrive after the half-year journey able to walk, at least. No crew returning from space after half a year ever have, even for weeks afterward. So we must get more data, between one gravity and none. Mars has 0.38 g; how will we perform there? Nobody knows.
Spinning a habitat at the other end of a cable, counter-balanced by a dead mass like a missile upper stage, is the obvious first way to try intermediate gravities. The International Space Station has tried very few innovations, and certainly nothing as fruitful as a centrifugal experiment. Until a livelier spirit animates the official space program, the tough jobs of getting into orbit cheaply, and living there self-sufficiently, will probably have to be done by private interests who can angle a profit from it. But not right away.
This is an historic moment, one of great opportunity. NASA can either rise to the challenge and scrap the shuttle, or just muddle along. An intermediate path would use the shuttles on a reduced schedule, while developing a big booster capable of hauling up the big loads needed to build more onto the station. This would be cost-effective and smart.
The past Director of NASA said to me a few years ago that he thought the agency had about a decade to prove itself. Around 2010 the Baby Boomers will start to retire and the Federal budget will come under greater pressure. Space could go into a slow, agonizing withering. He thought this was a distinct possibility if NASA did no more than fly around in cycles over our heads. "It has to go somewhere else," he said.
The obvious target that has huge scientific possibility is Mars. Did life arise there, and does it persist beneath the bleak surface? No robot remotely within our capability can descend down a thermal vent or drill and find an answer. Only humans are qualified to do the science necessary, on the spot.
A Mars expedition would be the grandest exploit open to the 21st century. It would take about 2.5 years, every day closely monitored by a huge Earthside audience and fraught with peril.
This is what we should be doing. Such an adventure would resonate with a world beset by wars and woes. It has a grandeur appropriate to the advanced nations, who should do it together.
The first step will be getting away from the poor, clunky shuttle, a beast designed 30 years ago and visibly failing now. How we respond to the challenge of this failure will tell the tale for decades to come, and may become a marking metaphor for the entire century.
As well, the engineers at NASA would be overjoyed to have a larger prospect before them, something better than patching up an aging shuttle that, in the end, was going nowhere.
Gregory Benford is a professor of physics and astronomy at the University of California, Irvine, a long-time advisor to NASA, and a novelist.
We keep on trying something different, however: multiple staging, solid strap-on boosters, tow ropes, mid-air refueling, wings, hydrogen-oxygen fuel, scramjets, giant factories to achieve scales of economy. And did I forget, helicopter rotors?
I am convinced that this level of blindness on the part of the entire aerospace community (exception Hunter, Stine, and me) is because God doesn't want us to go into space yet. If you're an atheist, substitute 'Advanced Alien Civilization with Stealth Mother Ship in Orbit' for God. But same thing. There's no way that six billion human beings could be more aversive to the simple, direct approach. Their minds must be clouded by something.
True, but I'd think that a couple hours daily of real gravity-simulating exercise would probably do a lot to prevent the problems of zero-G from setting in. Running the exercises at over 1G might help even more. For that matter, what about using the treadmill (if spinning on its own) as sleeping quarters?
BTW, yes I was thinking of 2001...
There is already a good example of what I am talking about. Consider the differences between the Apollo command module and the LEM. The LEM had to be shrouded on the Saturn to boost it into earth orbit, otherwise it could never have made it into space. Once in space, however, it worked just fine for transport to the lunar surface & back, because it was operating in the vacuum of space. But it could have never returned to earth. On the other hand, if the command module has been designed to do it all -- including the lunar landing & return mission -- it would have had to be so large that the spacecraft would have been impossible to ever even get off the ground. That is close to the problem we have with the shuttle -- it is designed to not only get the passengers into space and return them, but also haul up stuff for them to work on while in space (and often bring it back) -- stuff that could just as well have already been up there and stay up there.
If a space transportation system as I have described existed, then you could have both the rotating space stations with their artifical gravity as Arthur C Clarke first invisioned, and also zero-g facilities like the present ISS. Astronauts could be ferried back & forth between the two, on a daily basis if necessary. We could get to the point where nobody needed to work in a zero-g environment for more than 8-12 hours out of every 24, or maybe even less often. With a little experimentation the optimal balance could be found that would allow people to stay and work in space for years with no harmful effect to their health.
First flew in 1981. Advanced.
Like a beater 1981 Chevy, I guess.
--Boris
To your last sentence, exactly! The Russians just sent up an unmanned re-supply vehicle, which successfully docked with the International Space Station. I don't know what ultimately happens to the vehicle, but it sure is a lot simpler than the Shuttle.
I am not opposed entirely to manned space missions, but since a human life, especially from among the best and brightest, is sacred, we should be a bit more selective in what we send them up for. As for the ISS, perhaps it would have been more practical to develop a smaller vehicle to transport humans to and from it. The vehicles that were/are initially used to transport parts of the ISS should have been designed to become a part of the ISS. That's what I call efficiency.
I don't want to take my time to do the analysis since others are being paid to do just that. But I strongly suspect that the probablity of bringing a human being back from space is inversely proportional to the size of the vehicle. The Shuttle is just too damned big to be safe.
As for the last mission of Columbia, I believe that the "experiments" that were carried out were not worth the dollars, much less the lives of the seven astronauts. Yes, you may say that we have to transport people back and forth between earth and the ISS, now that we have the ISS, but how in the hell do you justify a half billion dollars to study spiders?
And before you start flaming, let me say that just before retiring from an aerospace company I was involved in a contract with the Naval Research Lab to conduct a "space experiment" on the Shuttle. It involved superconductivity. There was absolutely no way that the device would act differently in space than it did in our laboratory, but NRL spent hundreds of thousands of dollars to shoot it up into space - and they confirmed my analysis. And the astronauts received acclaim. But I feel that they were risking their lives for nothing, unless they were simply satisfied with just being in space.
If you recall, many of the "contractors" were laid off after the Challenger accident. However, not one federal government worker at NASA was laid off (RIF'd). What did they do during that 2 1/2 years? Obviously, those who were involved with the booster rockets were monitoring the developments at Thiokol. But what were all of the other NASA folks doing?
Bottom line, if there is a delay in launches of future Shuttles, I doubt that any - ANY - government workers will be affected. Contractor employees will be though.
That's just how it works with "government jobs".
The committees. You know what happens with committees. The one person who really knows how to get the job done has to sit and listen to a bunch of other people with other agendas. Then he gets outvoted. It comes down to committees because the funding comes from somewhere else not under the control of the one person. Program administrators then take over. They, too, don't know how to get the job done, but they sure know how to administer the project. The one person who knows how to get the job done sometimes is allowed to get the job done, but usually gets marginalized and eventually wanders off before he is booted out. So there's the project, and there's the funding, and the original objective will not be accomplished.
When's the last time you found yourself in awe of our exploits in space? I mean, really?
The whole program has become mainly a vehicle for expressions of multi-culturalism (every year we get someone who is the "first" of his her color/nationality/ethnicity/religion/social set to fly into "space.")
There are no plans to return to the moon, none to Mars, none to look at commercial exploitation of the asteroid belt, e.g.
Space exploration is as dead as our latest Shuttle crew, and it will remain that way until someone figures out how to make a solid buck from it, and governments (including and especially the U.N.) get out of the way.
Trying to give an honest answer, when I saw the Hubble Deep Field I was struck with awe. Then again, that might not qualify as our exploits. My layman's opinion is that Hubble has been good publicity and good science.
However, more to your point, I would agree that the national space program has stagnated somewhat. Even if you consider the moon landings a publicity stunt, which I do not entirely, the unity of purpose that nasa had during the Apollo program seems like a totally different NASA to me than the one of today.
It's kind of a chicken and egg scenario, in which NASA has no concrete goal to work towards so there is no solid support, but NASA doesn't receive the support nationally because to does not have one, over-riding goal which everyone understands. That's one thing the moon landings had that today's NASA doesn't, the public perception of doing something concrete.
Sure, they're doing things, even a lot of different things, even scientifically valuable things. However, there is a disconnect between what NASA is doing and the relevance those projects have on the life of the average person. Even if the moon landings were little better than a publicity stunt to shame the Soviets, that was something people could easily wrap their brains around. Everyone knew why we were doing, as it had direct connections to the Cold War.
So, in my layman's opinion, this is what NASA lacks today. People understand that NASA is doing things with our tax dollars, but there isn't an easily identifible thing it does that people can recognise, other than the shuttle. Now that the shuttle has had another catestrophic failure, this draws serious doubts into NASA's whole mission. I do not mean to lessen the sacrifice that the crew made when I say this, but maybe this will be a good thing for NASA in the long run.
I would wholeheartedly agree that private industry needs to be involved, and that until there is the potential for profit making space exploration will be limited. But at the moment, NASA is the big governmental program which is charting these new territories, as the opportunity costs for space travel are still too high in the private sector for anything other than manned probes. But, if we are going to have this federal program, what should it be doing? Watching spiders float about in a confused fashion?
What I think NASA could be doing ties in as neatly with national policy as the moon landings did with military technology, and that is energy policy. Energy policy is on everybody's minds, as much or more than the Cold War was in the late 50s early 60s.
In short what I think NASA should be doing is applying themselves towards one large and critical national problem, that of energy policy. I am speaking specifically about solar power satellites in geostationary orbit which beam down power in microwave frequencies. Though it is often said that our economy runs on oil, I would be more inclined to say our economy runs on electricity. We just use combustion for some specific things, but electricity is in every engine that is not powered by steam.
If NASA applied itself towards helping produce electricity, it is a tangible goal when the common man can easily understand. Not because the common man needs a dumbed down NASA, just the opposite. Rather it is something that everybody needs, which is to say energy. It gives them a reason to develop mineral resources near earth orbit, and a roadmap for jumpstarting private investment in the area. Energy production has a profit motive which the "pure" sciences to not. It also provides an alternative to nuclear enery generation even though I happen to support nuclear power, because uranium is a limited resource as with fossil fuels.
This is my layman's idea on how to make a buck from space exploration.
And now to distract you from my typograpical errors, the Hubble Deep Field:
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