Weather threatens shuttle Discovery launch

By Irene Klotz

CAPE CANAVERAL, Florida (Reuters) – Thunderstorms
threatened NASA’s plan to launch space shuttle Discovery on
Sunday on a mission critical to the future of the shuttle
program and the half-built International Space Station.

NASA forecasters predicted a 70 percent chance that weather
would delay the launch, as it did a planned launch on Saturday.
Flashes of lightning were visible before dawn at Cape
Canaveral, where the Kennedy Space Center is located.

No other problems were noted at the center, as U.S. space
agency workers began the process of filling the shuttle’s
massive fuel tank with super-cold liquid hydrogen and liquid
oxygen. Launch is set for 3:26 p.m. (1926 GMT).

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 $100 billion space station before the
shuttle fleet is retired in 2010.

“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 until the station is completed and the
fleet is retired.

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 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.