“They know it wasn’t the thermostat, and it wasn’t the circuit breaker associated with that. “They’ve been methodically testing for the past couple of days,” Beutel said. The plan calls for removing the switch box Monday and installing its replacement Tuesday. That did not happen…so we know we have a hard failure in that heater for that one auxiliary power unit.”Įngineers were still troubleshooting on Monday to identify the precise source of the electrical glitch, according to NASA spokesman Allard Beutel. “We tried to get the line to cool down by normal means to see if the thermostat on the heater would kick in. “We were not able to get to come to life no matter what we did,” said NASA’s shuttle launch director Mike Leinbach on Friday. Shuttle managers think the problem is associated with wiring from the one of these switch boxes - the aft load control assembly-2 - to one of the heaters. Power is routed through this switch box to the two thermostats and two heaters on each of the shuttle’s fuel lines. From each of its three auxiliary power units, electricity gets distributed by something called a load control assembly, which is essentially a 48-pound box of electrical switches. Frozen hydrazine could expand and crack open the fuel line, exposing the fuel, which could cause a fire upon reentry.Įndeavour’s launch was postponed on Friday when heaters in one of the shuttle’s power units failed.Įndeavour is powered by three fuel cells. The shuttle’s built-in heaters keep this from happening. Hydrazine fuel must be kept warm or the fuel lines will freeze. ET | NASA now says that repairs to replace and retest a faulty power distribution box has pushed the launch date to May 10 at the earliest.Īt the root of Friday’s scrubbed space shuttle launch is a simple fact about fuel. The crew also will transfer Endeavour’s orbiter boom sensor system to the station, where it could assist spacewalkers as an extension for the station’s robotic arm.Updated May 2, 6:00 p.m. AMS is a particle physics detector designed to search for various types of unusual matter. The crew will deliver the Alpha Magnetic Spectrometer-2 (AMS) and critical supplies to the space station, including two communications antennas, a high-pressure gas tank and additional parts for the Dextre robot. For NASA TV streaming video, downlink and scheduling information, visit: NASA Television will broadcast the crew’s arrival live. STS-134 Commander Mark Kelly and his five crewmates are set to arrive at Kennedy for prelaunch preparations on Thursday, May 12, at approximately 11 a.m. They also are completing retests of other systems powered by the switchbox and are closing out Endeavour’s aft compartment. Since Friday, Kennedy technicians installed and tested new wiring that bypasses the suspect electrical wiring and confirmed the heater system is working properly. The heater circuits prevent freezing of the fuel lines providing hydraulic power to steer the vehicle during ascent and entry. Technicians determined the most likely failure was inside a switchbox in the shuttle’s aft compartment and associated electrical wiring connecting the switchbox to the heaters. They also discussed the progress of repairs since Endeavour’s launch postponement on April 29.Ī short in the heater circuit associated with Endeavour’s hydraulic system resulted in the launch postponement. Space Shuttle Program Launch Integration Manager Mike Moses and Shuttle Launch Director Mike Leinbach announced the date at a news briefing Monday from NASA’s Kennedy Space Center in Florida. The STS-134 mission to the International Space Station is the penultimate shuttle flight and the final one for Endeavour. Launch attempts are available through May 26, except for May 21. NASA managers have set the liftoff of space shuttle Endeavour for 8:56 a.m.
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