Monday, April 05, 2010

Discovery crew adjusts inspections due to failed antenna

Discovery astronauts are preparing to inspect the orbiter's heat shields without the aid of a communications antenna normally used to beam images down to analysts in Houston's Mission Control Center.

The dish-shaped Ku-band antenna failed after being deployed on orbit not long after the shuttle's 6:21 a.m. blastoff today before dawn at Kennedy Space Center.

Without the communications link, the crew will record video of the reinforced carbon-carbon panels lining Discovery's wing edges and nose cap, carefully noting any indications of damage that could have occurred during the climb to orbit.

The video will be downloaded to the ground after the shuttle reaches the International Space Station around 3:40 a.m. EDT Wednesday.

The failed antenna also includes a radar mode typically used during docking operations, and its functionality is not yet clear. The crew has back-up tools including a hand-held laser device to help gather range and rate data as the orbiter approaches the station.

Shortly after the crew awoke around 8 p.m., Megan McArthur, an astronaut communicating with the crew from Houston, spent about 15 minutes reading a series of notes and schedule changes that normally would have been delivered by e-mail in an "Execute Package."

"I'm your voice-activated Execute Package today," she joked to Discovery commander Alan Poindexter.

The heat shield inspection will be executed in shifts by Poindexter, pilot Jim Dutton and mission specialists Dottie Metcalf-Lindenburger, Stephanie Wilson and Naoko Yamazaki of the Japan Aerospace Exploration Agency.

Before midnight, the team will use the shuttle's 50-foot, Canadian-built robotic arm to pick up a 50-foot boom extension equipped with TV cameras and laser sensors.

The boom will scan the port wing, nose cap and starboard wing looking for evidence of debris strikes. Video will be recorded in short, 40-minute segments instead of the usual three-hour stretches.

After today's launch, NASA officials reported seeing a several small peices of foam tear away from the shuttle's external tank more than four minutes into flight, after the period when they can hit the shuttle with dangerous force.

The heat shield survey was scheduled to start around 1 a.m. Tuesday and last about five hours, but could take a longer because of the lack of a live video downlink. Sequential still images sent to the ground using an S-band antenna will be visible on NASA TV.

This isn't the first time missions have experienced problems with the Ku-band antenna, though the issues weren't exactly the same as now, according to NASA TV commentators. Past instances include STS-126 in 2008, STS-92 in 2000 and the last shuttle-Mir mission.

Also on board Discovery, mission specialists Rick Mastracchio and Clay Anderson are setting up the spacesuits they'll use during three spacewalks outside the station.

For a more detailed schedule of events, click here to see the first draft -- "Rev A" - of NASA TV's STS-131 mission coverage schedule.

IMAGE: During a different mission, Discovery is shown in orbit with its Ku-band antenna deployed to the right of the crew cabin. Credit: NASA.

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