Monday, October 12, 2009

NASA To Swap Faulty Cables Before Shuttle Rollout

NASA is aiming to move shuttle Atlantis out to its Kennedy Space Center launch pad this week but faulty range safety system cables first must be swapped out and their replacements retested.

Atlantis and six astronauts are scheduled to blast off from launch pad 39A at 4:04 p.m. Nov. 12 on a mission to deliver supplies and equipment to the International Space Station, which is circling the planet in an orbit about 220 miles above its surface.

With the shuttle mounted atop a mobile launcher platform, a giant tracked transporter is scheduled to creep out of High Bay No. 1 in the Vehicle Assembly Building at 12:01 a.m. Wednesday. The 3.5-mile trip is expected to take about six or seven hours to complete.

Atlantis had been slated to rollout on Tuesday, but the move was pushed back a day after engineering encountered an electrical problem with an overhead crane in the 52-story assembly building.

The wiring issue delayed by 14 hours the mating of the orbiter Atlantis to an external tank with attached solid rocket boosters.

NASA and contractor engineers powered Atlantis up on Saturday night for the Shuttle Interface Test, which is designed to verify electrical and mechanical connections between the orbiter, its tank, its boosters and its mobile launcher platform.

The completion of the test was delayed when engineers detected lower-than-normal signal strength during tests on the shuttle's Flight Termination System -- a series of explosion devices that would be used to destroy the shuttle's booster if the vehicle were to careen off course and threaten populated areas.

The problem was traced to two faulty cable that route electrical signals from shuttle computers to the small pyrotechnics. One of eight hold-down posts on the shuttle's mobile launcher platform will be reopened so technicians can swap out the cables. The replacements then will be retested to make certain signal strength is within specifications.

The 11-day Atlantis flight will be the 129th shuttle mission and the 31st for Atlantis. It also will be the 31st mission to the International Space Station and the 16th post-Columbia shuttle mission.

Veteran shuttle pilot Charlie Hobaugh will serve as mission commander. The crew also includes pilot Barry Wilmore and mission specialists LeLand Melvin, Mike Foreman, Robert Satcher and Randy Bresnik. Nicole Stott, now serving as a flight engineer on the station, will return to Earth aboard Atlantis.

ABOUT THE IMAGE: Click to enlarge the NASA image of shuttle Atlantis being lowered onto a Mobile Launcher Platform in High Bay No. 1 of the Vehicle Assembly Building. You can also click the enlarged image to get an even bigger, more detailed view. The orbiter was mated last week to an external tank with attached solid rocket boosters. Engineers this week are performing tests to verify mechanical and electrical connections between the orbiter, its tank and boosters and its Mobile Launcher Platform. Photo Credit: NASA/Jack Pfaller.

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