Atlantis Shuttle Crew Set for Second Landing Attempt

This story was updated at 9:54 a.m. EDT.

CAPE CANAVERAL, Fla. -- NASA is hoping for a break in the weather in order to bring the space shuttle Atlantis and its seven-astronaut crew back to Earth later today.

Rain showers and low clouds near NASA?s Shuttle Landing Facility here at the Kennedy Space Center (KSC) prevented a Thursday return for the shuttle and its STS-117 astronaut crew.

The orbiter is now slated to land at 2:18 p.m. EDT (1818 GMT) at KSC.

?We?re going to be facing the same challenges at KSC,? NASA astronaut Tony Antonelli, serving as spacecraft communicator, told the Atlantis crew of today?s expected weather conditions.

Mission managers are also calling up NASA?s backup shuttle landing site at Edwards Air Force Base in California in case the weather proves untenable in Florida, he added.

Commanded by veteran shuttle flyer Rick Sturckow, Atlantis? STS-117 crew is returning home after a now 14-day mission to boost the power grid aboard the International Space Station (ISS).

The shuttle astronauts installed new starboard trusses and solar arrays, furled an older solar wing and swapped out one of the station?s three-person Expedition 15 crew. The crew also repaired a torn thermal blanket on Atlantis? aft Orbital Maneuvering System (OMS) pod using surgical staples and medical staplers scavenged from shuttle and ISS medical kits.

Returning to Earth with Sturckow are shuttle pilot Lee Archambault and mission specialists Patrick Forrester, Steven Swanson, James Reilly II, Danny Olivas and Sunita Williams.

Williams is returning to Earth after 194 days in space as part of the station?s Expedition 14 and 15 crews. She has set a new world record for the longest duration spaceflight by a female astronaut and was replaced by fellow U.S. spaceflyer Clayton Anderson during the STS-117 mission.

Deorbit decision

Atlantis carries enough supplies to stay in orbit until Sunday, though mission managers have set a Saturday deadline for any weather-related delays in order to keep a one-day margin in reserve in case of a technical glitch.

In all, there are two landing opportunities at KSC and three at Edwards, though some windows overlap.

If rain and low clouds again prevent Atlantis from landing at KSC on the first attempt, the shuttle could try to wait out the weather for an extra orbit and touch down in Florida at about 3:55 p.m. EDT (1955 GMT).

?It will be a real-time call,? NASA spokesperson Allard Beutel said Thursday.

But if, in that one orbit, the weather does not improve, the shuttle could instead press on towards Edwards for a 3:49 p.m. EDT (1949 GMT) landing thanks to a brief engine burn late Thursday by the Atlantis crew. That maneuver, mission managers hope, could allow Atlantis to reach Edwards before the arrival of high winds during two later California landing opportunities, which arise at 5:23 p.m. EDT (2323 GMT) and 6:59 p.m. EDT (2259 GMT).

?Sounds like a nice game plan,? Sturckow told Mission Control Thursday after hearing today?s landing options.

NASA prefers to land shuttles at KSC, home to the orbiters? hangars and launch pads, because of the time and cost saved to once more prime them for flight.

Atlantis is slated for a second launch this year in December, when the shuttle is expected to haul the European Space Agency?s Columbus laboratory to the ISS.

A landing at the Edwards site would cost an additional $1.7 million and add between seven to 10 days to ferry Atlantis back to KSC for refurbishment for its next mission, NASA officials said Thursday.

?Obviously, we?d prefer to stay at the Cape if we can,? John Shannon, NASA?s deputy shuttle program manager, before Atlantis? first landing attempt.

During their mission, Atlantis astronauts also helped Expedition 15 crew resolve a major Russian computer system shutdown last week that ultimately required an improvised set of shunts, or jumper cables, to bypass surge-protector like circuits in six vital control and navigation computers.

Expedition 15 astronauts removed the jumper cables from some of the computers Thursday in additional troubleshooting efforts to see if they would still function properly, but they would not, NASA officials said.

NASA is broadcasting the space shuttle Atlantis' STS-117 mission live on NASA TV. Click here for mission updates and SPACE.com's video feed.

• SPACE.com Video Interplayer: Space Station Power Up with STS-117
• IMAGES: Atlantis Shuttle?s STS-117 Launch Day
• Complete Shuttle Mission Coverage