Minor Damage Found On Space Shuttle

The BBC is reporting on minor damage to the space shuttle Atlantis revealed by a 10-hour inspection in orbit. On the shuttle's right side, near where the wing joins the body, inspection revealed a 21" (53cm) line of chips in the tiles that make up the vehicle's heat shield. "...more analysis by engineers would determine whether a 'focused inspection' was needed in that specific area. If so, astronauts would use sensors to determine the exact depth of the damage to the heat shield tiles. NASA has placed the space shuttle Endeavour on stand-by to rescue the crew of Atlantis if they are endangered." The crew couldn't shelter on the ISS in case of trouble, because their orbit is higher and on a different inclination.

Comments

Re:So what happens....

[Anonymous Coward]

The astronauts pile into the less damaged orbiter and come home in it.

Then, they get home and buy Powerball tickets, because those kinds of odds are nearly as good as winning. The Shuttle has more or less always sustained some tile damage during launch; its heat shield is replaced after every launch as it wasn't designed to be perfect (well, it originally closer to perfect when it was to be built of solid titanium, but plans change...) The damage turned out to be a significant player in Columbia's loss, as it happened that the part of the shield that was damaged was extremely critical to the proper functioning of that area.

OTOH, here we see an almost pristine heat shield. The damage is long, but it's very narrow, likely caused by a single piece of falling debris striking in multiple locations. This isn't going to prevent them from coming home in Atlantis.

Re:Rescue Logic

[Maddog Batty]

http://spaceflightnow.com/shuttle/sts125/090508sts400/

"When we made the decision, the odds were 1-in-473 that we would have a problem on the shuttle for which a rescue shuttle was the solution," Griffin said. "Now, there are a lot of problems you can have on the shuttle, right? There are a lot of ways you can die on the shuttle, which is what gives you the overall shuttle PRA (probabilistic risk assessment) of about 1-in-75 or so. So you're roughly five-and-a-half, six times likelier to die on the shuttle for some reason that the backup shuttle can't save you from than you are to die from one the backup shuttle can save you from. ... From a statistical point of view, it makes no real sense to have a backup shuttle.

"However, here's the flip side. ... Those numbers cannot be explained to politicians or the general public. And should we have a failure with those 1-in-473 or whatever odds it was, should we have a failure that the rescue shuttle could have saved you from and we had not done it, the consequence to NASA would have been incalculable. We would appear to have been cavalier with human life, we would appear to have not taken every possible precaution, we would appear to have been coldly calculating the odds and rolling the dice with people's lives. And the appearance of behaving that way, in my judgment, was unacceptable. I could not risk that for NASA."

While the overall risk of impact damage is about three times higher for a Hubble mission than a flight to the International Space Station, it is not as bad as flight planners initially feared.

"We know we're accepting a little higher risk for this flight," Steve Stich, manager of the orbiter project office at the Johnson Space Center, said in an interview. "That's why we've tracked it very carefully."

Even factoring in debris from a satellite collision in February between a defunct Russian Cosmos satellite and an Iridium telephone relay station, the mean odds of a catastrophic impact during the Hubble mission are on the order of 1-in-229, which is well below the 1-in-200 threshold that requires an executive-level decision by NASA's leadership.

A preliminary analysis put the odds at 1-in-185, but the numbers improved after recent radar observations and consideration of the shuttle's orientation in space during the Hubble mission. The planned orientation, or attitude timeline, reduces the crew's exposure to impacts that could damage critical areas of the ship's heat shield, the coolant loops in the shuttle's cargo bay door radiators and cockpit windows.