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Space Shuttle to Receive Emegency Repairs

Posted by timothy on from the friendly-callers dept.

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.'"

3 of 427 comments (clear)

  1. Paranoia. by Inominate · · Score: 5, Insightful

    It's a minor problem, which ordinarily would have gone unnoticed. It's probably happened many times before. NASA is just being paranoid because they can't afford another accident. Alternative theory, NASA wanted to find something wrong that isn't really a danger and prove they can fix it, and that there is no danger anymore in space travel.

    1. Re:Paranoia. by rhadamanthus · · Score: 5, Interesting
      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.

      --
      Slashdot needs to interview Natalie Portman.
  2. The real reason isn't because it's an emergency! by BritImp · · Score: 5, Informative

    I spoke with a guy from the Mission Management Team (MMT) tonight here in Cape Canaveral. He confirmed that such small pieces of gap filler are not expected to affect the creation of the barrier layer during re-entry, and so do not pose a threat to the orbiter.

    The real reason for this 'repair' is because this whole mission is to "test orbiter repair techniques" - and these virtually irrelevant pieces of gap filler provide an unexpected, but very fortunate opportunity to try a real repair technique out in a relatively safe and controlled fashion.

    NASA doesn't yet know if it's even possible to have an astronaut perform repair-type work on the underbelly of the orbiter - they think it would be possible, but they have no hard data to say it can be done.

    But these small bits sticking out give them the perfect excuse to go test it and get some real-world experience on the issue.

    If it looks like the astronaut might damage some of the Thermal Protection System tiles down there, they'll just terminate the repair attempt and fly home as-is. If not, they'll demonstrate that astronauts can go under an orbiter and perform repair tasks down there safely and without harming the TPS.

    But I'll bet you'll hear the popular press making too much out of this as usual...