Bringing It Back to Earth Part 2

>> Sunday, May 16, 2010


The problem with the technical posts is that I have to go fetch all the specifics to put them together. So they take longer. Still, I want to get this out so I'm continuing with it.

Clearly, given that the needs required to allow humans to return to earth are so significant, throwing a bit of hardware or samples in with the rest is relatively benign compared to effort to do so on an unmanned mission. By definition (for all manned missions where we expect our crew to return), the vehicle needs life support systems, heat shields, attitude controls rockets and/or flight controls, deorbiting rockets (and fuel), some sort of slowing down mechanism (chutes, retrockets, flight surfaces, etc) and, frequently, some sort of transponder so that we can find them. Add a few kg of extra equipment/samples/experiments, etc is really no big deal.

But, if you have an unmanned satellite or space vehicle, you are talking about adding ALL of this equipment that otherwise wouldn't be necessary - except the life support system. For a remote spacecraft (outside earth's orbit) just the rocket for return alone is a huge added weight and complication.

But, before the advent of the Shuttle, the US and the Russians were still limited to, at most, a few hundred kg of additional baggage as it were. Most Russian spacecraft, those that aren't manned, are designed to burn up during reentry. There was one model that could return unmanned but it's payload was tiny relative to the trouble (~150 kg). Soyuz TMA, the manned Russian craft used for the ISS, can return 50 kg (and sometimes a smidge more).

The Shuttle, however, can bring down tens of thousands kg of payload, in the payload bay and/or the middeck. Trash, experiments, satellites, equipment, modules. Of all the precedents the Shuttle inaugurated, a world where equipment that failed could be returned and evaluated (as has been done extensively with repaired items on the Hubble Space Telescope - and even refurbished and reinstalled), this accomplishment is perhaps the greatest triumph of them all.

Oh, don't get me wrong, it's impressive that it's largely reusable, but there are some down-sides to that. And it has a pretty impressive payload capacity to begin with, no doubt. But, a big enough rocket, we can get that much payload, and more, as far or farther. Getting it back down? I wonder if we'll ever be able to do so much again. I doubt it will be in my lifetime.

I hope I'm wrong about that.

There are many triumphs particular to the manned portion of space exploration, not the least of which is that sending man into space means you have to lick two tough problems - how to get him out there and how to get him back. History makes it pretty clear which one's tougher.

4 comments:

  • Project Savior
     

    That was the huge advantage that the shuttle had over every other rocket system was the huge amount of "stuff" it could bring back to Earth.
    But the technology isn't lost. I'm sure once a profitable reason for bringing stuff back from space is around, Pharmaceuticals, Micro-Gravity Manufacturing, He3 ect. That the knowledge gained from the Shuttle will be revived and integrated into the new tech.

  • The Mother
     

    Are there people out there who don't get this?

    I suppose that a ton of folks look at the big rockets required for liftoff and assume that that's the most immediate danger to a manned mission--but our experience with the shuttle shows that it's only around half the problem.

  • Stephanie Barr
     

    You'd think that, the Mother, but even at NASA it is often brushed off, taken as a given.

    Of all the deaths in flight, 11 of them (from a total 18) involve return, STS-107 and both of the fatal landings by the Soviets, Soyuz 1 (where the parachutes failed to inflate properly and the retros didn't fire) and Soyuz 11 where an equalization valve was jarred open and evacuated the capsule.

    Actually, some of the near misses were pretty exciting, such as the landing in a frozen lake where they couldn't be pulled back up for more than a day - and they survived. Fascinating stuff. http://en.wikipedia.org/wiki/Space_accidents_and_incidents

    This is what the paper I'm presenting this week is on, accidents and near-misses and lessons learned.

  • Jeff King
     

    Great info... i would not have ever know this if it wasn't for you sharing... thx.

    keep up the good work, can't wait for more.

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