Mission Discovery: Shuttle Astronauts Prepare To Head Home

European Space Agency (ESA) astronaut Christer Fuglesang (foreground) and Robert Curbeam, both STS-116 mission specialists, work with controls on the aft flight deck of Space Shuttle Discovery their mission to continue assembly of the International Space Station. Fellow mission specialist Nick Patrick appears at left, with pilot William Oefelein in the background. CREDIT: NASA.

CAPE CANAVERAL, Fla. -- Seven astronauts are spending what is expected to be their last full day in orbit aboard NASA's space shuttle Discovery today as their 13-day flight to the International Space Station (ISS) draws towards its close.

Discovery's STS-116 astronauts, commanded by veteran spaceflyer Mark Polansky, will put their orbiter through its reentry paces during a series of flight systems checks later today in preparation of their planned Friday return.

"It was a true team effort, and I think this mission really showed that," Polansky told flight controllers Wednesday. "We are really looking forward to getting back to see a great holiday."

NASA mission operations representative Phil Engelauf said Wednesday that Discovery appears to be in fine shape for a Friday landing. The results a final inspection of the orbiter's heat shield are expected to be announced during a NASA mission status briefing later today.

In addition to their standard pre-landing Flight Control Systems checks, Discovery's STS-116 crew will spend time today stowing some last-minute cargo items and setting up a special recumbent seat for European Space Agency astronaut Thomas Reiter. Unlike the Discovery astronauts, who have been in orbit for just over 11 days, Reiter is returning to Earth after almost half a year of in space as an ISS crewmember [image].

Small satellites take flight

Discovery astronauts successfully launched two small payloads from the aft end of the shuttle's cargo bay late Wednesday and plan to deploy one more before the end of today.

STS-116 mission specialists Christer Fuglesang and Joan Higginbotham fired a pair of spring-loaded experiments into orbit to kick off experiments sponsored by the U.S. military.

At 7:19 p.m. EST (0019 Dec. 21 GMT), they unleashed the Microelectromechanical System-Based (MEMS) PICOSAT Inspector (MEPSI). The payload featured two tiny vehicles--each the size of a coffee-cup--lashed together with a tether and designed to test a low-power satellite's ability to inspect larger spacecraft in close proximity.

"Houston, we have a successful MEPSI deploy," Fuglesang said.

At 8:56 p.m. EST (0156 Dec. 21 GMT), the astronauts deployed the Radar Fence Transponder (RAFT): a pair of five-inch (12.7-centimeter) wide cubes built by students for the U.S. Naval Research Laboratory to test the limits of the military's Space Surveillance Radar Systems in Texas, Alabama and Arizona. The small cubes are also designed to relay messages for display across the Internet as well a being capable of beaming a digitized voice, NASA officials said.

MEPSI took photos of Discovery, which were later relayed to the shuttle's crew, as it departed and RAFT was successfully detected by its users as it passed over Oregon, Mission Control reported.

"OK!" Polansky exclaimed. "Everybody's happy."

The astronauts are expected to deploy a small atmosphere-observing satellite dubbed ANDE at about 1:19 p.m. EST (1819 GMT) today.

Landing preparations

Polansky and his crewmates are due to land at one of three NASA shuttle runways either in Florida, New Mexico or California.

While exact landing site, however, will depend on weather conditions at the time, NASA is hoping to put Discovery down here at the Kennedy Space Center (KSC), where the shuttle launched spaceward on Dec. 9, to minimize turnaround time and costs.

Engelauf said flight controllers plan to attempt a 3:56 p.m. EST (1856 GMT) landing at KSC during Discovery's first return window Friday, which occurs during the shuttle's 202^nd orbit around Earth. A subsequent orbit offers landing opportunities at KSC, White Sands Space Harbor in New Mexico and Edwards Air Force Base in California--in that order--though the target runway would likely be tapped before Discovery is due to leave orbit, he added.

"More than likely we will pick a site to aim for on each [revolution] and get in there," Engelauf said, adding that the window in which to fire Discovery's engines to make any of the three landing strips spans only six minutes. "It's a really short decision time and you pretty much have to make your mind up before you get there."

An off-going shift of mission controllers commended the STS-116 crew's work after their successful ISS construction mission to install a new piece of the ISS, rewire the outpost's power grid and deliver a new astronaut and cargo for the station's Expedition 14 mission. Discovery's crew also wedged in an extra spacewalk to furl away a stubborn ISS solar array.

"The flexibility you guys maintained to finish this mission was outstanding," said NASA astronaut Kevin Ford, serving as spacecraft communicator for the first of three flight controller shifts working with Discovery's crew. "Have a Merry Christmas, happy holidays and you guys have a safe trip home."

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