By Irene Klotz
CAPE CANAVERAL, Florida (Reuters) - Astronauts climbed aboard the shuttle Discovery on Friday, hoping the weather holds for a midnight launch of a 13-day mission to stock the International Space Station with new lab gear, food and spare parts.
NASA plans to end a spate of launch delays with an 11:59 p.m. EDT (4:59 a.m. British time on Saturday) liftoff from the Kennedy Space Centre in Florida. The flight has been on hold since Tuesday due to poor weather and a technical issue with a drain valve in the ship's fuel tank.
After determining that a sensor and not the valve was at fault, the U.S. space agency developed alternate procedures the launch team could use to verify the valve was properly closed for liftoff.
The problem did not recur while the shuttle was fuelled for the launch attempt on Friday, leaving only the weather as a concern for flight.
As the crew left their quarters, the rain and clouds suddenly dissipated, bolstering NASA's hopes of getting its 128th shuttle mission off the launch pad.
"We have our fingers crossed that weather will indeed cooperate with us today," said NASA launch commentator Mike Curie.
STATION NEARING COMPLETION
Three-time shuttle veteran Rick Sturckow, 48, leads the Discovery crew and first-time flier Kevin Ford, 49, serves as pilot.
The mission specialists are Pat Forrester, 52, with two previous flights; Christer Fuglesang, 52, and Danny Olivas, 44, who both have made one previous flight; and rookies Jose Hernandez, 47, and Nicole Stott, 46.
Fuglesang is Swedish and the rest are Americans.
Discovery is carrying more than seven tonnes of science instruments, food, supplies and spare parts for the station, which is nearing completion after more than a decade of work 220 miles (355 km) above Earth.
The United States, Russia, Europe, Japan and Canada will have spent about $100 billion (61.5 billion pounds) on the outpost by the time it is finished late next year or in early 2011 after seven more visits by the shuttles, including Discovery's current mission.
NASA then plans to retire its shuttle fleet and rely on its partners and commercial carriers to ferry cargo to the outpost.
Discovery's flight marks the final time a space station crewmember will launch on a shuttle. Stott is scheduled to swap places with returning station flight engineer Tim Kopra.
Stott is expected to fly back to Earth on NASA's next shuttle mission in November but her replacement will arrive on a Russian Soyuz capsule. NASA is paying Russia about $50 million per seat to ferry crewmembers to and from the station.
The agency is also soliciting proposals from U.S. launch services companies interested in providing rides for astronauts.
(Editing by Jim Loney and John O'Callaghan)
