STS-118 Update

After days of analysis and simulations, NASA has decided not to attempt repairs of the gouged heat shield on Endeavour's underbelly before the shuttle returns to Earth.

Simulations run earlier in the week suggests the part of the shuttle's skin under the gouge will be subjected to heat of 325 degrees during re-entry. The critical level is 350 degrees. That may seem a close call, but the heat will build and then ease as Endeavour slows in its flight through the atmosphere.

NASA clearly believes it has a margin of safety in this decision that outweighs the risks involved in attempring a repair in orbit. We can only hope NASA is correct.