NASA Slips Discovery Launch To Feb. 27

NASA decided this evening to push the planned launch of Discovery back to Feb. 27 to give engineers more time to carry out tests aimed at making sure critical valve trouble doesn't endanger its seven-member astronaut crew.

Another consideration: Making certain engineering teams do not work too many consecutive weekends prior to a long International Space Station assembly mission. Saturday is Valentine's Day and Monday is a federal holiday -- President's Day.

Liftoff time of Feb. 27 would be 1:32 a.m. EST. Landing would be on March 13.

Senior managers will meet next Friday to decide if ongoing tests show the type of valve failure that cropped up on Endeavour's launch last November will not jeopardize Discovery and its crew.

One of three valves that route gaseous hydrogen from the shuttle's main engines to the liquid hydrogen reservoir within its external tank failed to operate as intended on the Endeavour flight. Post-flight inspections showed the lip of the valve -- which is the size and shape of a lawn sprinkler -- chipped off.

The valves are critical to keeping pressures within the tank at proper levels as propellant is drained from it during the shuttle's nine-minute climb into orbit.

Too much pressure could cause a relief valve on the tank to vent gaseous hydrogen into a potentially flammable environment. Too little pressure could results in an engine shutdown or break-up in flight.

NASA had planned to launch Discovery on Thursday but decided to delay the flight until Feb. 19, and then Feb. 22, to perform tests and analyse resulting data.

Some of the ongoing tests are aimed at determining the size of the largest piece of debris that might be liberated from a cracked valve. Others are designed to determine whether liberated debris might puncture main propulsion system lines that run from the engines into the external tank.

Discovery mission commander Lee Archambault leads a crew that includes pilot Tony Antonelli and mission specialists Joseph Acaba, John Phillips, Steve Swanson, Richard Arnold and Koichi Wakata of the Japan Aerospace Exploration Agency.

Discovery will haul up the last segment of the International Space Station's central truss. The 31,000-pound girder is equipped with the outpost's fourth and final set of American solar wings.

Wakata will become the first Japanese astronaut to serve a long-duration tour on the station. He'll replace current station flight engineer Sandra Magnus, who will return to Earth on Discovery.

ABOUT THE IMAGE: Click to enlarge and save the NASA image of shuttle Discovery silhouetted against the dawn's early light as it made the 3.5-mile journey to Kennedy Space Center's launch pad 39A in January. You can also click the enlarged image to get an even bigger, closer view. Photo credit: NASA/Troy Cryder.