The Space Shuttle Endeavour was damaged last week during liftoff when a piece of foam smacked the shuttle. Now NASA has a few choices and none of them are ideal.
The damage has penetrated through two heat tiles, which are 6 inches, by 6 inches in size and 1.12 inches thick. The impact of the shuttle and foam created a 3-by-2-inch hole that extends to the bottom of the tile. Under the tile are two more layers, a piece of thermal felt and, below that, the shuttle's aluminum skin, neither of which are currently damaged.
The foam that hit Endeavour was hardened by ice, which made the impact more damaging, according to sources at NASA.
There are nearly 32,000 heat tiles on each orbiter. They are made from extremely pure sand — 99.7 percent — that has been crushed into very small silica fibers and added to a ceramic binder. Heat tiles protect the shuttle when it re-enters Earth's atmosphere upon its return from space.
NASA has three options:
NASA astronauts have unwittingly flown home with damage before, but that is because before the Columbia mission in 2003, they had no way of knowing if a shuttle was damaged. Since then, the standards have changed.
Now, with news of the incident known around the world, NASA now must decide whether the crew should fly home on a damaged shuttle — teacher-turned-astronaut Barbara Morgan is on board.
NASA will run tests in the arc jet facility at Johnson Space Center in Houston to determine whether the damaged area will burn through on re-entry.
Spacewalking astronauts can repair the damage using one of three methods: using a heat-resistant paintlike substance; using a puttylike substance that can be caulked into the hole or by screwing on a plate over the damage.
NASA's third option would allow Endeavour to remain docked to the space station, using the new power system to maintain the shuttle as long as possible. The crew is equipped with 68 days' worth of consumables and, in a highly unlikely scenario, the Shuttle Discovery could be launched Oct. 5 to rescue the stranded astronauts.
The big question for NASA, then, will be whether it wants to launch another shuttle with a known foam problem.