Wednesday, January 13, 2010

Endeavour Preps Pick Up After Cold Weather Delays

NASA aims to start loading hazardous propellants aboard Endeavour and its solid rocket boosters today after a cold weather delay that had a ripple effect, pushing back delivery of the shuttle's prime payload to launch pad 39A at Kennedy Space Center.

The U.S. Tranquility module and the Italian-made Cupola now will be transferred to the pad on Saturday. But NASA officials say the delays will not cause a Feb. 7 target launch date to slip.

Endeavour and six astronauts remain scheduled to blast off from pad 39A at 4:39 a.m. Feb. 7, the middle of a 10-minute window to put the shuttle and its crew on course for a ground-up rendezvous with the International Space Station. NASA is scrambling to deliver some critical ammonia hoses to KSC that are required to hook Tranquility up to the station's cooling system. An agency-level flight readiness review will be held Jan. 27. A firm launch date will be set at that time.

Launch preparations in the meantime are picking up at KSC after some cold weather delays. At the pad today:

Technicians are setting out to load toxic propellants into tanks aboard Endeavour and its twin solid rocket boosters, which straddle the shuttle's 15-story external tank. Temperatures must be above 40 degrees Fahrenheit to proceed with the loading of hydrazine and nitrogen tetroxide into tanks that feed the shuttle's Orbital Maneuvering System engines, its Auxiliary Power Units and Hydraulic Power Units in the shuttle's twin solid rocket boosters.

The shuttle's three APUs provide hydraulic power to steer its main engines in flight and control its aerosurfaces, landing gear, brakes and nosewheel steering during atmospheric reentry and landing. The HPUs steer the nozzles of the solid rocket boosters. Engineers are troubleshooting low pressure readings from the Fuel Supply Modules that provide hydraulic power to the rock and tilt actuators on the right-hand solid rocket booster. The problem at this time is not expected to impact the Feb. 7 target date.

The propellant-loading operation had been slated for earlier this week but was delayed as a result of cold weather. The delay prompted NASA to push back the delivery of the Tranquility module and its attached Cupola to the pad. Launch managers want to complete the hazardous hypergolic propellant load prior to payload delivery to the pad.

Tranquility and the Cupola are being readied for the transfer to pad 39A at the Space Station Processing Facility in the KSC Industrial Area. The move now is scheduled for 4 a.m. Saturday.

ABOUT THE IMAGES: Click to enlarge the first NASA image of shuttle Endeavour at launch pad 39A after rollout earlier this month from the Vehicle Assembly Building. You can click to enlarged image to get an even bigger view of the shuttle and its reflection in wetlands surrounding the pad. Photo Credit: NASA/Jim Grossmann. The second NASA image shows the Tranquility module and the attached Cupola being hoisted into a payload canister for transfer to the launch pad. Photo Credit: NASA/Amanda Diller.

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