Loss Of Weather Contingency Day May Prove Challenging

NASA reports the space shuttle Discovery undocked from the International Space Station at 5:10 pm EST Tuesday, ending an eight-day stay. Pilot Bill Oefelein guided the shuttle through a partial fly-around of the space station, before firing Discovery's rockets to begin the final separation from the station and the trip back home.

The STS-116 crew bid farewell to the International Space Station’s Expedition 14 crew before entering Space Shuttle Discovery. The hatches closed between the two vehicles at 2:42 pm Then, the two crews conducted leak checks before Discovery undocked.

Discovery is scheduled to land at 3:56 pm Friday at the Shuttle Landing Facility at Kennedy Space Center, FL. However, forecasted weather conditions may force the shuttle to land at either Edwards Air Force Base in California, or New Mexico's White Sands Missile Range.

The STS-116 crew had a busy stay at the station. The crew continued the on-orbit construction of the station with the addition of the P5 spacer truss segment during the first of four spacewalks. The next two spacewalks were devoted to the rewiring of the station’s power system, leaving it in a permanent setup. A fourth spacewalk was added to allow the crew to retract solar arrays that had folded improperly.

Discovery also delivered a new crew member and more than two tons of equipment and supplies to the station. Almost two tons of items no longer needed on the station will return to Earth with STS-116.

Little Room For Error In Tight Schedule

The addition of the fourth spacewalk bumped Discovery's scheduled landing by 24 hours... and forced mission managers to face a high-risk decision. As the shuttle only has 48 hours of reserve fuel onboard -- meaning Discovery can stay in orbit no longer than Saturday -- NASA mulled over scrapping a final inspection of the shuttle's heat shield to make up for the extra day spent at the ISS.

NASA decided to go ahead with the inspection, now scheduled for Wednesday. But that means the loss of one of Discovery's two weather contingency days... and as a result, NASA could be forced to land the shuttle in a less-than-optimal location, and perhaps even in less-than optimal weather conditions.

ABC News reports weather forecasts for Friday and Saturday at all three landing sites don't look good.

FMI: www.nasa.gov/shuttle