CAPE CANAVERAL, Fla. - NASA has resolved problems with the space shuttle Discovery's fuel tank and reset its launch on cargo-delivery run to the International Space Station for Feb. 24, officials said Tuesday.
The flight, one of the last for the space shuttle program, has been on hold since November.
Additional testing on the fuel tank earmarked for the following flight on the shuttle Endeavour, which will carry the station's Alpha Magnetic Spectrometer particle detector, likely will delay that mission's launch from April 1 to April 18.
Whether Endeavour commander Mark Kelly, whose wife is wounded U.S. Rep. Gabrielle Giffords, will be flying has not yet been determined, said NASA's associate administrator for space operations, Bill Gerstenmaier.
Giffords, an Arizona Democrat, was shot in the head outside a Tucson grocery store on Saturday while meeting with constituents.
She survived the attack, which killed six people and injured 13 others, and is recovering. Kelly, a U.S. Navy captain and veteran of three previous shuttle missions, took a leave of absence to be with his wife.
"We're going to let Mark decide what he needs to do," Gerstenmaier said, adding that it would be inappropriate for NASA to comment further.
Discovery's flight has been on hold since a launch attempt on Nov. 5 ended due to a fuel leak. A second, and far more vexing issue surfaced the same day when inspectors found a crack in the tank's insulating foam, a key safety concern for NASA, which redesigned the tanks after the fatal 2003 Columbia accident.
The foam crack eventually led NASA to cracks in underlying metal support beams.
After two months of analysis and testing, engineers have traced the problem to a combination of manufacturing issues and stresses put on the tank when it is filled with supercold liquid oxygen and liquid hydrogen, said shuttle program manger John Shannon.
The fix, engineers determined, is to install supportive reinforcements on the metal beams, known as stringers.
"It's an elegant fix to the problem," Shannon told reporters. "I'm very confident that we have finally figured this out."
Endeavour's tank uses stringers from a different manufacturing lot, so Shannon expects that a fueling test and X-rays of the beams at the launch pad will be all that's needed before that shuttle is cleared to fly.
NASA is hoping to receive funds for an extra shuttle mission over the summer to stash a year's worth of supplies on the station. The fuel tank being prepared for that flight likely would need the reinforcements, Shannon said.
NASA is shutting down the 30-year-old shuttle program due to high operating costs and to free up funds to start developing a new space launch system that can carry people and cargo to asteroids and other destinations beyond the station's 220-mile-high orbit.
Russia already has taken over the job of flying NASA astronauts to and from the station, though the U.S. government is trying to speed development of a commercial space flight industry to pick up its business.
After the shuttles' retirement, station cargo deliveries will be handled by Russian, European and Japanese spacecraft, with plans for two U.S. firms — Space Exploration Technologies and Orbital Sciences Corp. — scheduled to take over NASA's share of the work. Both companies plan demonstration flights to the space station this year.