NASA Tackles Late Fuel Tank for Shuttle Flight

Space Shuttle Discovery's Launch Delayed to May 31
The space shuttle Discovery's External Tank-128 rolls out of the Test and Checkout Building at NASA's Michoud Assembly Facility in New Orleans en route to the Kennedy Space Center in Florida for the STS-124 mission.
(Image: © Lockheed Martin.)

A five-daydelay in the arrival of a newly designed external tank is not expected to delayDiscovery's May 25 launch.

However, the loss of timevirtually eliminates days off for technicians, Discovery flow directorStephanie Stilson said.

External Tank 128,scheduled to arrive from the New Orleans factory on Thursday, was delayed bybad weather and is now scheduled to arrive Tuesday.

The tank has titaniumbrackets on the liquid oxygen feed line, solderedECO-sensor connectors, a redesigned ice-frost ramp and minor changes to themetal structure.

Discovery is scheduled tobe attached to the tank and a pair of solid rocket boosters on April 27 andthen to roll out to the launch pad on May 5. That schedule leaves enough timeto load the 37-footKibo science laboratory and perform last-minute checks on the spaceship andrelated systems.

"We feelconfident," Stilson said.

To make room for Kibo inthe payload bay, Discovery must fly without the 540-pound orbital sensing boomused to photograph the thermal tile to check for damage.

Endeavour, however,borrowed Discovery's boom for its current mission and willleave it at the International Space Station. After arriving at the spacestation, Discovery will pick up the boom and use it for inspections of thethermal tiles.

NASA's three shuttles sharetwo inspection booms, and Discovery is rigged so the boom it picks up in spacewill work properly, Stilson said.

Discovery also has beenequipped with new radiator hoses to prevent kinks that worried managers duringAtlantis' last mission.

"We did a few cyclesof the payload door," said Stilson. "It worked exactly how we hopedit would."

Also, Discovery's UHF radiois working fine. NASA managers considered borrowing Discovery's radio whenEndeavour's radio would not function on its high-power mode. However, theydecided that the radio's two low-power modes would suffice.

"We don't ever like topull anything out of the ship," Stilson said. "If they had needed it,by all means, we would have taken it out of Discovery."

Tuesday's arrival of theupdated external tank marks the incorporation of all the changes recommendedsince the Return to Flight in 2005.

The tank, which is 153.8feet long and 27.6 feet in diameter, carries nearly 5,000 pounds of foam, whichkeeps ice from building up on the outside.

The tank modificationsinclude less foam on the titanium brackets that hold the liquid oxygen feedline and modifications to foam on other parts of the tank. A piece of foambroke loose and smashed a hole in Columbia's wing during launch on the 2003mission that ended in disaster.

Changes to the tank willnot slow processing toward launch, Stilson said.

"I'm getting a veryclean tank when it gets here," she said.

NASA isbroadcasting Endeavour's STS-123 mission live on NASA TV. Click here for SPACE.com'sshuttle mission coverage and NASA TV feed.

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