Live At KSC: Back-Up Shuttle Landing Site Called Up

NASA is calling up a back-up landing site in California but still aims to bring shuttle Atlantis and seven astronauts back to Kennedy Space Center on Saturday.

Weather permitting, that is.

As it stands, the Atlantis astronauts are scheduled to fire braking rockets at 8:02 a.m., sending their spaceship toward a 9:15 a.m. landing at NASA's coastal Florida spaceport.

Two other opportunities are available: 10:54 a.m. and 12:32 p.m. However, NASA likely would only exercise the first two because an attempt to land at 12:32 p.m. would make for an extremely long day for the crew, which faces several hours of post-flight medical exams and a news conference 4.5 hours after touchdown.

Forecasters at the Spaceflight Meteorology Group at Johnson Space Center in Houston expects conditions in central Florida to be similar to those that force NASA mission managers to forego two opportunities to bring the crew home today.

There is a chance of thunderstorms and lightning within 30 miles of the shuttle runway, and there also is a possibility of low cloud ceilings that would obstruct the view of the landing strip on final approach.

The stormy weather is being pushed into the area by an upper-level low-pressure system now in the eastern Gulf of Mexico. That front is expected to move to the northwest by Saturday morning, and NASA hopes storms might be pushed north of the KSC area as a result.

But forecasters still expect some instability and moisture in the area. What's more, the meteorologists note, a seabreeze is expected to build as the atmosphere heats up after sunrise. The seabreeze could result in coastal rain showers and low cloud decks.

The weather outlook in Florida prompted Entry Flight Director Norm Knight to call up NASA's back-up landing site at Edwards Air Force Base in California. There are landing opportunities at Edwards at 10:44 a.m., 12:23 p.m. and 2:02 p.m.

The weather at the Mojave Desert military base is expected to be near-pristine. Only a slight chance of a stiff headwind is in the forecast there for Saturday and Sunday.

"Any decisions on the landing site, of course, will be dictated by the weather conditions in Florida and California not only Saturday but also looking toward Sunday to determine if the trends to continue to improve in Florida," said NASA flight commentator Kyle Herring.

The shuttle has enough liquid hydrogen and liquid oxygen onboard for its three fuel cells to generate enough electricity to remain in orbit until Monday.