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Benford on Space Exploration
gid-goo writes "Gregory Benford looks at what we should do in the aftermath of the Columbia accident. Is the shuttle, or the International Space Station for that matter, useful? Or just payola to aerospace interests and a means for keeping Russian rocket scientists employed?" Benford's comments about the necessity of a closed biosphere and of some way for astronauts to stop muscle and bone loss are far more insightful than the usual discussions about where our space exploration priorities should lie.
The main part of the Benford's article is that the primary problem of space travel is dealing with the lack of gravity to maintain human bone and organ health.
Cats spend up to 20 hours a day sleeping and yet still manage to stay fitter than most human gymnasts.
Purring creates vibrations through the cat's body helping to maintain muscle and bone density.
Transducers in an astronaut's suit could produce similar resonant vibrations. These vibrations could simulate the stresses of g-forces by rapidly moving the astronaut a very small distance back and forth.
Sorry I didn't connect the dots for you in the original post.
This article on spacefuture.com has a pretty good analysis of what centripetal forces we should be looking for in deciding to build a rotating space station. It takes into account not only the physics, but also the effects of this artificial gravity on humans (since there is a significant effect due to Coriolis forces that make it behave differently from natural gravity).
Laika! But she was kind of a bitch.
Really - Valentina Tereshkova, the pilot of Vostok 7. The only thing remarkable about Sally Ride (or other "female firsts") is that women in the west were prevented from pursuing that field for so long. The Soviet Union had no shortage of flaws, but they were more equal-opportunity than the West.
And actually I rather dislike the story of Laika. She was sent to her death (an unpleasant one, slow suffocation, dehydration, or burning up) and they knew they had no way to get her down. The Americans weren't much better, killing lots of monkeys and chimps. At least by the time they actually managed to get a primate in orbit it was late enough that they were also able to land it safely. Maybe there's a message there about prematurely putting humans in space...
I'm not sure putting our priorities on designing the next shuttle is what's really needed since it is basically a truck to LEO. In retrospect, in the early 70's NASA would have been much better off ramping up production and building scores of Saturn V's, a hundred Saturn 1B's and a few dozen Skylabs. With 20/20 hindsight, big dumb boosters were probably the best way to go three decades ago and that probably still holds true today. Who knows, maybe we still would have lost 1 out of 50 Saturn launches as well, but at least would have a lot more interesting stuff everywhere between LEO and the Moon for the same money.
For me I'm much more interested in spending the bulk of NASA's limited budget on interesting payloads that leave LEO rather than developing trucks to deliver the payloads to LEO. After all, 60's technology was fine for getting us to LEO and the Shuttle isn't going to take NASA to Mars.
Since the beginning of the shuttle program there were plans for a shuttle derived unmanned heavy lift vehicle that basically looked like a huge boxcar strapped to the side of the external tank. The only recoverable parts were the engines themselves, which would parachute to Earth after entering the atmosphere with an ablative heat shield. I believe that with most of the weight of the shuttle structure, wings, and crew cabin removed, such a booster would have had nearly the capacity of the Saturn V. It seems that such plans could be resurrected and within a year or two we have a heavy lift vehicle that can take advantage of economies of scale for shuttle solid rocket boosters and external tanks which I believe, ironically, are the cheapest parts of the shuttle. NASA can then use the proven Soyuz (thank you very much Russia for keeping the rocket and capsule assembly lines going) to get human crews into orbit until some suitable replacement is made.
Once NASA again has heavy lift capability it can then concentrate on truly interesting payloads that can take us to Mars and beyond. I'll cry if NASA does get the go ahead for a Mars mission and comes up with a scheme where dozens of shuttle missions (either the remaining three vehicles or next generation shuttles) are required to build the spacecraft in orbit from small components.
- It would be a money sink that would never pay back its construction costs - a tax money sink, because no commercial firm could ever get investment funding (not this side of AD 3000 anyhow).
The cost is actually quite modest. Figures between $5bn and $40bn have been mentioned. At the lower end of the scale, this is about 15 shuttle launches. At the high end, it's a tiny fraction of the US defence budget. The benefits to the first company or government who does this are the ability to launch satellites at a tiny cost, build further space elevators for (relatively) next to nothing, and in the long term the full exploration and exploitation of natural resources in space.- It would be the worst sort of governmental monopoly, a choke point where everyone must bow and scrape to the groundbound owners, in order to get a lift.
This is certainly true in the short term. In the longer term, many elevators can be built by different companies and governments. (Only the first elevator is expensive - once that's working the others are cheap to build).- It would be The Definitive Terrorist Target - and the bad guys only have to get lucky once. It would be utterly indefensible from a simple kamikaze attack, being so long that no weapons installation could keep cover over its whole length without weighing it down.
The proposal is to have an exclusion zone around of the order of 10-100 miles. It would be extremely hard to fly unnoticed into such an area. Attacks from underneath (submarines, etc) and attacks from people actually travelling on the elevator are harder to deal with. In the end it doesn't matter however. Once one elevator is up, you build more, and you keep a few reels of carbon nanotubes "parked" in space to cover this eventuality and natural disasters.- And it would be a catastrophe waiting to happen, when (not if) it snaps and rains megatons of carbon cable down upon the ground below.
Yes, we've all read Kim Stanley Robinson too. He's a good writer, but not a great scientist. A break in the cable is most likely to happen in the first 20-40 miles (ie. in the atmosphere). So the 20-40 miles of cable drops down - into the exclusion zone which is just a harmless area of sea. The top part slowly drifts off into space. There's even the possibility of repairing a broken cable by lowering more down to earth before it drifts off.Rich.
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