That’s not a bad idea in concept–either placing a retaining layer over the foam, or spraying the foam through some kind of structural matrix analogous to rebar in concrete–but in reality the foam isn’t all one continuous piece, but rather a layer spread over a variety of protrusions. For instance, this picture shows where the piece of foam that came from Columbia’s ex-tank was located. TPS (thermal protection systems, or a fancy name for foam or cork insulation) breaking off and falling has always occured with any booster utilizing cryogenic fuel or oxidizer; if you look back at old Saturn V launch gantry film clips you’ll see a veritable storm of TPS falling as it launches, shaken free by the engine vibrations. For a vertical stack this generally isn’t an issue; the detritus falls outboard and in any case the rocket segments and interstages are robust enough to survive a glancing hit from a chunk of foam, but as someone else (Hyperelastic?) mentioned in another thread on the issue, the Shuttle’s parallel stack and large-aspect leading surfaces make it more vulnerable to damage from falling insulation, especially if it is frozen and hard.
The proper solution is to redesign the tank with sufficient insulation inside (or at least in the critical areas) such that external insulation is either unnecessary or thin enough not to be a risk. This is not, though, a trivial task to undertake, and has many other implications (reduced payload and fuel capacity, difficulty with fabrication and inspection, et cetera). NASA clearly wanted to avoid virtually redesigning the entire tank so they threw in a few obvious fixes that ameliorate the problem without getting to the root cause (i.e. foam falls off).
Which is why I suggested a single piece cover akin to a nylon stocking. It doesn’t need to be heavy or particulary strong since it’s just preventing chunks from falling off and into the path of the Shuttle. The chunks could even slide down and fall out the bottom for all I care.
Huh. There was all this talk last year about flying the Shuttle unmaned. There didn’t seem to be any question of if it were possible, and I know I’ve read someplace it’s totally doable with just some changes to the avionics software.
This article seems to take as a given launch, orbit, de-orbit, and landing unmanned as a given. The author only seems concerned about the complications involved in automatically maneuvering the Shuttle to the ISS.
I gotta agree with you there. In addition to your example of Russia’s ‘Big Dumb Boosters’, the B-52 bomber comes to mind.
It’s just that the space shuttle isn’t exactly one of those tried-and-true mature technologies.
Hell, you could say it about anything - why stop where you did?
But the thing is, our current manned space program doesn’t accomplish anything of note, utilitarian or not. It doesn’t take us anywhere new, it doesn’t add anything of importance to our knowledge base. It’s all about driving a very expensive, unreliable, dangerous bus to low earth orbit (and the space station) and back.
Actually, it’s more of a “tried-and-failed” technology. :smack:
Well, I can’t argue with you (much) there. What little our manned space program does that is adding to our knowledge and capabilities could be more cheaply, effectively, and safely done with systems other than the Shuttle. That doesn’t mean manned exploration isn’t worthwhile overall, though I don’t think anyone can make a vaild short-term economic case for it. The purpose should be to explore–not perform high school science experiments in orbit or suit political machinations down below.
I’m with you on that. But having agreed with you there, here’s the problems I run into:
We’ve already been to the moon. There’s no intellectually compelling reason to make a return trip.
Any manned exploration beyond the moon is going to be twenty times as difficult, and probably a similar multiple on the expense. That’s raising the ante really, really high - you could solve major problems here on Earth for that sort of money.
Unmanned probes are already doing a terrific job of exploring the other planets and their satellites, sending back lots of data and great pictures, for a fraction of what it takes to keep the shuttle program alive.
I think what would be more interesting than a manned Mars mission would be an unmanned Alpha Centauri probe. There would be some interesting engineering/IT challenges, such as:
i) Finding a way to propel it there fast enough that we’d have a chance to see how the mission turns out;
ii) developing software that will enable the probe to deal with challenges at the other end all by itself (the 8.6 year round trip for a radio signal requires that); and, speaking of which:
iii) being able to broadcast a signal over that distance that we can pick up at this end, with a transmitter and power source small and light enough to make the trip.
Getting a close-up view of another star/solar system would be pretty spectacular.
I have to take a bit of an issue with this; we’ve been throwing money at many of the “major” humanitarian problems on Earth for decades now with no resolution in sight; the truth is, we’ve the agricultural and logistical ability to provide a diet with at least minimum nutritional requirements to everyone on the planet. We could defeat, or at least control, most of the major infectious illnesses that afflict the nations of the Third World. And so forth. But the combination of political will, social cooperativeness, and applied wisdom seems to be lacking, for which no amount of money will compensate. Despite the billions spent by the UN and European nations on Africa, their problems are worse than ever, and many make the case that the manner and conditions by which the aid was provided served to increase the problems.
We could shut down the space program and put the money into social programs–but based on past experience, this wouldn’t guarantee, or even offer much confidence, that this would serve to alieviate those problems. The Proximire Fallacy doesn’t hold water.
I can’t disagree with this, either; as I stated, there’s no short-term ROI on manned space exploration. The reason to do it is…so we develop the technology to do it. It is our future. (Whether it makes sense to do it now is another question.) Nonetheless, there are a large number of missions in which remotely-controlled probes are not only as effective (and cheaper than) human missions, but actually superior; one doesn’t have to worry about returning a probe, or providing for food and water, or unstuffing a jammed toilet half-way to Titan.
