Live In Orbit: Shuttle Heat Shield Unscathed

Blogger Update: NASA's Mission Management Team officially cleared shuttle Atlantis' Thermal Protection System for reentry during their meeting this afternoon.

An inspection of shuttle Atlantis heat shield components turned up "zero areas of interest" but NASA nonetheless will keep counting down to a potential rescue mission until its Hubble Space Telescope servicing crew starts its return to Earth.

Wielding a sensor-laden inspection boom, the astronauts surveyed the shuttle's port and starboard wings as well as its composite carbon nose cap on Tuesday and then beamed imagery and laser data to Mission Control.

Engineers reviewing the imagery found no significant damage, and NASA's Mission Management Team is expected to clear the shuttle for reentry after a review that is under way at this time.

NASA nonetheless is stepping through a three-day launch countdown to keep the agency in a position to launch Endeavour and four astronauts on a rescue mission if some systems failure or other contingency crops up before a scheduled landing Friday.

Countdown clocks picked up at 6 a.m. today and are ticking toward a T-zero at 7:34 a.m. Saturday.

Endeavour and the rescue crew will remain on standby until the shuttle begins its atmospheric reentry.

The weather for landing on Friday, meanwhile, looks terrible. Forecasters at the Spaceflight Meteorology Group at Johnson Space Center say there is a chance of thunderstorms and lightning within 30 miles of the shuttle landing strip here at Kennedy Space Center.

The outlook is so grim that Mission Control had the astronauts start powering down non-essential systems on Atlantis to conserve electrical power-production capability.

Atlantis will have three opportunities to land at KSC on Friday: 10:01 a.m., 11:39 a.m. and 1:17 p.m. Landing opportunities at KSC on Saturday would come at 9:16 a.m., 10:54 a.m. and 12:32 a.m.

The shuttle has enough power-production capability to remain in orbit until at least Sunday. Power conservation efforts might yield an extra day if need be.