Astronauts Scan Space Shuttle's Heat Shield
The International Space Station as seen from space shuttle Discovery after undocking on Nov. 5, 2007 during the STS-120 mission.
Credit: NASA TV.

CAPE CANAVERAL - The seven astronauts on board the space shuttle Discovery scanned their spacecraft's heat shield for potential damage Monday and are gearing up for a planned Wednesday landing.

NASA mission managers said today that they expect engineers to clear the spacecraft tomorrow for a Nov. 7 arrival around 1:02 p.m. EST (1802 GMT) at Kennedy Space Center (KSC). Discovery successfully undocked with the International Space Station (ISS) this morning.

Rick LaBrode, lead shuttle flight director for the STS-120 mission, said eight potential impacts by micrometeorites or space junk were detected during Discovery's 13 days in space, but he is confident the anomalies pose no threat.

"All of these are expected to be cleared with the inspection that we're performing today," LaBrode said. The potential impacts to Discovery's heat-resistant panels were recorded by sensors mounted to the shuttle's wing leading edges, which bear the brunt of searing atmospheric reentry.

As for what the shuttle's sensors picked up, space shuttle program manager Wayne Hale explained that the harsh environment of space--which can swing from scorching to icy temperatures in moments--likely caused the anomalies.

"There are no indications of any damage," Hale said, but noted engineers on the ground will pore over the data retrieved by Discovery's sensor-tipped extension boom.

Homeward bound

As the STS-120 crew wrapped up the thorough heat shield inspection, shuttle commander Pamela Melroy took a moment to look outside the window and deliver a landing-day forecast.

"We can see the runway from orbit, so we're thinking the weather there is looking pretty good!" Melroy told spacecraft communicator Tony Antonelli at Mission Control of the KSC landing site. Antonelli joked that he would forward her report to weather officers for review.

As of right now, flight controllers said only windy conditions are a concern for landing day, with gusts currently reaching about 25 mph (40 kph).

Hale said Melroy opted for a daylight landing for pilot George Zamka because she felt more comfortable with the option. The descending orbit--a northwest-to-southeast path--will take Discovery across the heartland of America, which has not been attempted since the loss of Columbia in 2003.

Hale explained that noctilucent clouds, less air to slow the space shuttle down and extra propellant required to make the entry are the major reasons why it's not often attempted. But better visibility, he said, is the bonus.

"It is a basic fact that landing in the daylight is safer and easier than landing in the dark," Hale said.

Wednesday's current forecast here at KSC calls for sunny skies and wind gusts of 15 mph (24 kph).

If conditions sour, the STS-120 crew will have several opportunities to land at other sites: California?s Edwards Air Force Base at 2:28 p.m. EST (1928 GMT) or 4:02 p.m. EST (2102 GMT, New Mexico?s White Sands Space Harbor at 2:31 p.m. EST (1931 GMT) or 4:04 p.m. EST (2104 GMT), or another attempt to land here around 2:35 p.m. EST (1935 GMT).

Melroy and her crew delivered a 31,500-pound (14,288-kilogram) room to the space station, relocated a massive solar array truss and made an unprecedented repair of a torn solar wing during their mission. Tomorrow the crew will make final preparations for landing.