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NASA Reports on Endeavour’s Tile Damage

I reported on Friday that Endeavour had suffered a gouge on its underside after last week’s launch. The shuttle astronauts have used a laser and camera system mounted to the end of the shuttle’s robotic arm to measure the exact dimensions of the scrape, and here’s what they found:

The gouge is located about 1.2 meters away from Endeavour’s right landing gear door, and measures 9 cm by 5 cm long. This takes it across two of the shuttle’s tiles. NASA believes that a chunk of foam dislodged from the fuel tank, fell down, carved out this hole, and left some secondary damage further down the shuttle.

What’s worrying is that during this initial strike, the hole goes all the way down to the shuttle’s undercarriage, exposing some of the felt filler material underneath. Without any preventative measures, this could become a weak point for hot plasma during the shuttle’s reentry through the Earth’s atmosphere.

With an accurate accounting of the gouge’s dimensions, NASA engineers will now build a mockup of the damaged section and expose it to reentry conditions. They’ll see what kinds of risks the area will face if left unprotected, and then explore the different kinds of on-orbit repair materials the astronauts can use. To repair this damage, the shuttle astronauts can cover it with insulating paint, screw on a protective plate, or squeeze in some heat absorbing epoxy-like goo.

Although it sounds like bad news, there’s some good news to go along with this. This region struck by the foam experiences less heat on reentry than the rest of the shuttle; the spacecraft’s nose and wingtips get the hottest. The breach also occurred right over top of a piece of the spacecraft’s structural framework, so the additional aluminum will give the shuttle more armor to protect against the superheating.