Space Shuttle to Receive Emegency Repairs

Tycow writes "The BBC are reporting that Discovery needs emergency repairs - dangling material has been spotted on the belly of the shuttle, and NASA are worried they could cause overheating on re-entry. 'Nasa is concerned the dangling material - called gap fillers - could cause part of the shuttle to overheat as it re-enters the atmosphere.The type of repairs being planned have never been conducted by astronauts on a spacewalk before.'"

Comments

Tough cloth

[fembots]

According to NYTimes, this is what they're planning to do:

The astronaut would first try to remove the cloth, which is glued in place, by pulling it out with his gloved hand, she said. If that failed, he would use a set of forceps to tug the filler out or to hold the cloth while he cut it off with scissors, she said.

Are they saying that this piece of cloth (which may be removed by (1)pulling it out with bare hand, (2)poking it out or (3)cutting it off with a pair of scissors) won't simply burn away during re-entry?

Re:Paranoia.

[rhadamanthus]

NO. Boundary layer transition is not a very well understood phenomenon to begin with, and in this case you pushing the limits of both flight experience and analytical capability. Going from laminar to turbulent flow above mach 18 results in some very serious heating, ultimately effecting not just the thermal system, but also the structural margins.

Most importantly, this trip would spill over the side of vehicle and run down streamlines into the wing leading edge. Analysts put the increased heat loads even in a "best case" situation at 80% increase. At those temperatures (almost 3300F), the SiC coating will start to degrade. Dispersion in the entry tajectory could lead to an additional 150F. At that temperature the SiC will ablate, exposing the carbon-carbon substrate. It will oxidize and the temperature will skyrocket to 4000F. At that temp kiss the wing goodbye.

That all being said, I think it could make it down - the uncertainty in this situation is increasing conservatism - but I sure as hell won't take that risk when the EVA is quick and relatively simple.

Re:...and?

[Buran]

Have you ever seen footage of tiles being taken out of an oven and handled immediately afterward with bare hands? Notice the hot spot in the middle of the tile and that the outer parts of it are no longer glowing. This means that the outer part of the tile isn't that hot.

Had the titanium skin not been removed, there would have been allowances made for keeping it solid. Unfortunately, instead everything had to be re-engineered for flying without it.

Wrong.

[Vo0k]

Reasons why Russians flew Buran just once? A successful unmanned flight? (something US shuttles aren't capable of!)

1) To prove they can (cold war thing)
2) To waste no more money on a failed conception.

In the US, the shuttles are a pet of the military, government and different agencies. NASA would gladly retire them a long time ago, but they aren't allowed to. Russians recognized that Buran, despite being way better than the US shuttles, is still a bad design - too much redundant mass to be lifted into the orbit, too many parts that may fail, costs saved on reuse of the shuttle totally obliterated by costs of extra fuel, preparation and rebuilding non-reusable parts. Shuttles as such are a failed design and should be abandonned.

What we need is:
- a dedicated human transport vehicle. Something like the shuttle, just WAY smaller. Less weight, less energy wasted, less parts. 4-6 people, to orbit and back. Maybe launched from a plane, maybe from the ground, like a shuttle.
- a versatile orbital transport vehicle. Never meant to reenter the atmosphere, possibly docked to the space station most of the time. Automatic repairs, repairs on spacewalks, readjusting orbits of satellites, etc. refuelled with supplies delivered from Earth, but not much fuel required really.
- a cargo transport rocket. No need to limit thrust to grant human survival like in case of shuttles. Just transport cargo to orbit. Parts reusable in "best effort" manner, that is, drop on a parachute, if it's damaged/destroyed - no biggie. Cheap transport into space.
- emergency landers. Like the Soyuz capsules. Say, the human transport got damaged on launch and is incapable of reentry. Leave it on the orbit as another orbital transport, send the crew back in capsules.