Dec. 6, 2007

Mike Curie
Headquarters, Washington
202-358-4715
michael.j.curie-2@nasa.gov

Candrea Thomas
Kennedy Space Center, Fla.
321-867-2468
candrea.k.thomas@nasa.gov

RELEASE: 07-266

NASA POSTPONES SPACE SHUTTLE ATLANTIS LAUNCH; AIMS FOR FRIDAY

CAPE CANAVERAL, Fla. - NASA has delayed Thursday's planned launch of
space shuttle Atlantis on its STS-122 mission to the International
Space Station. The next liftoff opportunity is Friday at 4:09 p.m.
EST.

Shuttle program managers decided to postpone Atlantis' launch at 9:56
a.m. because of an issue with a fuel cut-off sensor system inside the
external fuel tank. This is one of several systems that protect the
shuttle's main engines by triggering their shut down if fuel runs
unexpectedly low. During countdown activities Thursday morning, two
sensors failed a routine prelaunch check. There are four engine
cut-off, or ECO, sensors inside the liquid hydrogen section of the
tank, and Launch Commit Criteria require three of the four sensor
systems to be functioning properly.

The tank's liquid oxygen and liquid hydrogen will be drained from the
tank, and preparations will begin for a possible launch attempt
tomorrow. NASA's launch rules have a preplanned procedure that states
in the case of ECO sensor system failure, engineers need to drain the
tank and verify all the sensors are working as they go dry. This and
other data will be discussed at a Mission Management Team Meeting at
2 p.m., when a decision will be made whether to attempt to launch on
Friday. A news conference will follow that meeting at 4 p.m.

During Atlantis' 11-day mission, the crew will install and activate
the European Space Agency's Columbus laboratory, which will provide
scientists around the world the ability to conduct a variety of life,
physical and materials science experiments.

Atlantis' crew consists of Commander Steve Frick, Pilot Alan
Poindexter, mission specialists Leland Melvin, Rex Walheim, Stanley
Love and European Space Agency astronauts Hans Schlegel, from
Germany, and Leopold Eyharts, from France.

For the latest information about the STS-122 mission and its crew and
more information about engine cut-off sensors, visit:

http://www.nasa.gov/shuttle