Space Shuttle Endeavour to Launch No Earlier Than May 16

CAPE CANAVERAL -- NASA managers have retargeted space shuttle
Endeavour's launch to no earlier than Monday, May 16. After a meeting
on Friday, they also extended the length of Endeavour's STS-134
mission to the International Space Station from 14 to 16 days. If
Endeavour launches on May 16, liftoff would be at 8:56 a.m. EDT.

At 3 p.m. on Monday, May 9, NASA Space Shuttle Program Launch
Integration Manager Mike Moses and Shuttle Launch Director Mike
Leinbach will hold a news conference at Kennedy Space Center in
Florida to discuss the progress of repairs since Endeavour's launch
postponement on April 29. The news conference will air live on NASA
Television and the agency's website. Reporters may ask questions from
participating NASA centers or by calling into a phone bridge.

Kennedy technicians are continuing work to resolve an issue in a
heater circuit associated with Endeavour's hydraulic system that
resulted in the launch postponement. Technicians determined the
failure was inside an aft load control assembly, which is a switchbox
in the shuttle's aft compartment, and possibly its associated
electrical wiring.

Although the root cause of the failure in the switchbox has not been
found, technicians are replacing hardware that could have caused the
problem. The faulty box was changed Wednesday, and a test of nine
shuttle systems powered by the new box is under way.

This weekend, technicians will install and check out new wiring that
bypasses the suspect electrical wiring connecting the switchbox to
the heaters. They also will run the heaters for up to 30 minutes to
verify they are working properly and complete retesting of the other
systems powered by the switchbox.

The shuttle has three Auxiliary Power Units (APUs) that provide
hydraulic power to steer the vehicle during ascent and entry. The
hydrazine fuel lines on each APU have two heater circuits that
prevent the fuel from freezing while the shuttle is in space. NASA
launch commit criteria and flight rules require all APUs and heater
circuits to be operational for launch. On Endeavour's first launch
attempt, one of two heaters for APU-1's fuel line did not work.
Engineers confirmed the circuit in the original switchbox that
directed power to the heaters was shorted out.

Launch attempts are available through May 26. May 21 is the only day a
launch is not an option because it would lead to a May 23 docking
with the space station. May 23 is when three of the space station's
Expedition 27 crew members undock and return home in their Soyuz
spacecraft. Managers reviewed the STS-134 mission timeline and
determined the Endeavour crew can accomplish all objectives even with
the departure of the three station crew members.

To use the phone bridge for the May 9 news conference, reporters must
have valid media credentials issued by a NASA center or for the
STS-134 mission. Journalists planning to use the phone bridge must
contact the NASA Johnson Space Center's newsroom at 281-483-5111 no
later than 2:45 p.m. Newsroom personnel will verify credentials and
transfer reporters to the phone bridge. Capacity is limited and
available on a first-come, first-served basis.

For NASA TV streaming video, downlink and scheduling information, visit:

http://www.nasa.gov/ntv

Endeavour's six astronauts will return to Kennedy on May 12. For the
latest information about the shuttle mission and its crew, visit:

http://www.nasa.gov/shuttle

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