NASA mission managers delayed the planned February launch of the space shuttle Discovery for the third time late Friday, with liftoff now slated for no earlier than Feb. 27 pending the completion of ongoing fuel valve tests.
Mission managers will review Discovery's launch readiness during a planned Feb. 20 meeting to determine if the shuttle is prepared to fly a two-week construction flight to the international space station by Feb. 27. If so, the shuttle would be primed for a 1:32 a.m. ET liftoff on launch day, NASA officials said.
The new delay will give engineers more time to complete a series of impact tests on shuttle fuel control valves at several NASA centers across the country, agency officials said. NASA announced the new launch delay after a daylong review on Friday to discuss the tests.
"As you can expect, with any issue of this complexity, there's a tremendous amount of data that's being collected," said Kyle Herring, a NASA spokesman at Johnson Space Center in Houston. "In fact, data was coming in from testing during the meeting."
Valve tests ongoing
Discovery was initially slated to launch on Feb. 12, but last week mission
managers delayed the launch by one week, then again to no earlier than Feb. 22, to allow engineers extra time to evaluate the shuttle's fuel control valves.
There are three fuel control valves on a space shuttle — one for each main engine. They are designed to pop up much like a lawn sprinkler head to route gaseous hydrogen fuel through a set of plumbing lines and into a hydrogen reservoir inside the orbiter's attached 15-story external tank. The valves ensure a shuttle's hydrogen tank maintains the proper pressure during the 8½-minute launch into space.
During the November launch of the shuttle Endeavour, engineers found that a chip from one of the metal valves broke free and flew into the plumbing lines leading to the external tank. The incident did not hinder Endeavour's launch, which reached orbit successfully. But NASA engineers want to be sure that a similar event, if it occurred during Discovery's launch, would not puncture the shuttle's vital plumbing lines and cause catastrophic damage.
NASA engineers have been working long hours for the last three weeks to perform high-fidelity impact tests using shuttle equipment. NASA's space shuttle program manager, John Shannon, wanted to give them more time to analyze the data before discussing an official launch target during the flight readiness review meeting on Feb. 20, Herring said.
"They wanted a little more time between the [flight readiness review] and the launch date to close out, if they need to, any open items," Herring said.
Commanded by veteran spaceflier Lee Archambault, Discovery's seven STS-119 astronauts plan to swap out one member of the space station's crew and deliver the final set of U.S. solar arrays to boost the orbiting lab's power grid during their mission. Four spacewalks are planned for the spaceflight.
Discovery has until March 12 to launch toward the space station and begin its 14-day construction flight. If the shuttle is unable to fly by then, NASA would stand down until after a Russian Soyuz spacecraft launches a new crew to the station around March 26, Herring said.
Earlier Friday, astronauts aboard the international space station said that while they were looking forward to the arrival of Discovery's crew, they were more than willing to wait until mission managers decide it was safe for the shuttle fly.
"We have complete confidence that they'll make the right decision on flight rationale based on solid data," space station commander Michael Fincke of NASA radioed down to Mission Control at Johnson Space Center.
Discovery's delay means a longer stay in space for NASA astronaut Sandra Magnus, a station flight engineer who has lived aboard the orbital outpost since last November.
Magnus is due to return to Earth aboard Discovery after nearly four months in space. Her replacement, Japanese astronaut Koichi Wakata, will arrive aboard the NASA shuttle to join the station's Expedition 18 crew, then stay on to serve with the next crew — Expedition 19 — when it arrives in late March.
Wakata, a veteran spaceflier, is Japan's first long-duration astronaut. He is due to return to Earth aboard another NASA space shuttle later this summer.
Discovery's STS-119 mission is NASA's first of up to six shuttle flights scheduled for 2009. The other missions include several space station construction flights and the final overhaul of the Hubble Space Telescope.
The shuttle's delay is not expected to affect the planned May 12 shuttle launch toward the Hubble Space Telescope and a subsequent space station construction flight, NASA officials said.