Florida weather still a problem for shuttle launch

CAPE CANAVERAL, Fla, July 2 (Reuters) NASA planned to try again today to launch space shuttle Discovery from Florida on a mission considered critical to the future of the US shuttle program and the half-built International Space Station.

The flight is only the second since the 2003 Columbia accident and another disaster or serious problem likely would end the program. NASA is hoping to fly 16 more missions to finish building the 0 billion space station before the shuttle fleet is retired in 2010.

The first launch attempt yesterday was canceled due to clouds and a potential for lighting near the seaside launch complex. The same weather is forecast for today, prompting NASA meteorologists to predict a 60 percent chance of another delay.

''We can't control the weather and we have very strict rules.

We're not going to launch this vehicle unless it's safe to do so,'' said launch director Mike Leinbach.

Shuttle safety has been at the forefront of the program since the Columbia disaster, which claimed the lives of seven astronauts. NASA has twice redesigned the shuttle's fuel tank, which triggered the accident.

The agency's top engineer and chief of safety wanted more repairs on the tank before Discovery was launched, but were overruled by NASA administrator Michael Griffin.

Griffin decided to fly without the additional repairs, arguing that in the unlikely event foam falls again from the fuel tank and damages the shuttle, the crew could stay aboard the space station and await rescue.

BUILDING THE SPACE STATION Delaying the launch, Griffin added, would have put more pressure on the shuttle program, which must finish building the space station before the shuttle fleet is retired. No other vehicles can deliver and install the station's remaining trusses, solar arrays and laboratories.

The agency plans two more flights this year and about four per year thereafter.

NASA had hoped to resume space station construction last year, but the shuttle's fuel tank failed its first test flight.

Engineers then removed two long wind deflectors from the tank, which had shed foam during Discovery's 2005 liftoff.

Additional work is pending on foam covering 37 metal brackets.

Work on the half-built space station has been on hold for nearly four years while the shuttles were grounded for repairs.

In addition to proving the new tank design, Discovery's mission will pave the way for NASA to resume station construction as early as September, when a new set of trusses and solar arrays are scheduled to arrive.

The Discovery crew must fix the station's rail cart, which was shut down in December after it severed cables needed for power, data and video transmissions.

The cart, which operates on tracks on the outside of the station, is used to haul equipment to various work sites.

The shuttle also carries a new crew member for the station, which has been short-staffed since 2003 to save on supplies while the shuttles were grounded.

REUTERS SB RN1057