Discovery's Commander Confident Space Shuttle Will Launch
STS-114 commander Eileen Collins will make her fourth spaceflight aboard the space shuttle Discovery.
Credit: NASA/JSC.

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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