CAPE
CANAVERAL, Fla. - With an exact launch date for their STS-114 mission still up
in the air, seven space shuttle astronauts are hanging tight here at NASA's
Kennedy Space Center (KSC), the spaceflight's commander said in a statement
released Saturday.
"My
crew will remain in quarantine for the near future, maintaining our proficiency
for this mission," said veteran astronaut Eileen Collins, commander of STS-114
mission aboard the shuttle Discovery, in the statement. "We are keeping in
close touch with the troubleshooting plan; we have confidence that the best
people are working it."
Shuttle
officials said that they may be able to launch Discovery late next
week, but only if engineers get lucky and are able to find and fix the
sensor system glitch soon. But that's not set in stone, and launch officials plan
instead to launch the shuttle mission four days after a fix is made, they
added.
Twelve
teams
of engineers gathered from across the country are working through the weekend
to solve an external tank fuel sensor anomaly that cropped up during Discovery's
July 13 launch countdown and forced mission managers to scrub
the attempted space shot. But on Friday, shuttle program managers said they
still did not know if the glitch was with the fuel level sensor itself, the
complicated electronics box it reports to aboard Discovery or the lengthy
wiring that runs between the two.
Collins
said the plan developed by engineers to track the glitch "is impressive, and we
are very proud of the work they are doing!"
Collins
and her six STS-114 crewmates were strapping into their seats aboard Discovery
when flight controllers scrubbed the launch attempt.
A
liquid hydrogen fuel level sensor near the base of the orbiter's
propellant-filled external tank had failed a standard countdown test, in which
all four of the sensors are forced to falsely report 'dry' indicating an empty
tank.
The
faulty engine cutoff (ECO) sensor reported a 'wet' reading, or a full tank. All
four of the sensors must perform properly in preflight checks in order to
launch, since they track dwindling fuel levels during launch and allow
Discovery's main engines to shut down before running out of fuel. If the
engines continue to fire without propellant, it could spell disaster for the mission.
NASA
experienced anomalous readings from engine cutoff sensors in a separate
external tank in April, when pad engineers test
fueled the 526,000-gallon tank with its liquid hydrogen and liquid oxygen
propellant. After an initial investigation and second
tanking test yielded no answers, shuttle official labeled the incident an "unexplained
anomaly." They later switched
Discovery to its current external tank, which bears an additional heater to
prevent extensive ice formation.
NASA's
STS-114 mission is the agency's first attempted shuttle flight since the 2003
Columbia disaster that destroyed on orbiter and killed its seven-astronaut crew
as they reentered the Earth's atmosphere. The STS-114 flight is expected to
test a series of new orbiter inspection and repair techniques, deliver much
needed supplies to the International Space Station (ISS) and validate safety
modifications to shuttle external tanks.
NASA
has until July 31 to launch Discovery's STS-114 mission and still meet the
lighting conditions needed to photograph the orbiter's flight, external tank separation
and tile-covered underside as it docks at the ISS. If the agency fails to
launch by that date, it will have to wait until a Sept. 9-24 window to launch
with proper lighting.
"While the launch delay is disappointing, we have strong confidence that the
mission will launch safely and successfully, and we fully support our NASA
leadership for taking the time required to understand the problem," Collins
said.
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