Shuttle Discovery sails away from space station

By Irene Klotz

HOUSTON (Reuters) – Space shuttle Discovery sailed away
from the International Space Station on Saturday, leaving
behind a third full-time crewmember on the station and high
hopes that NASA can quickly resume construction of half-built
outpost.

The shuttle, which arrived at the station nine days ago, is
due back on Earth Monday to conclude only the second mission
since the 2003 Columbia accident.

“Have a safe journey back, soft landings and we’ll see you
on the ground in a few months,” space station astronaut Jeff
Williams told the Discovery crew as the shuttle slipped out of
its docking port.

The primary purpose of Discovery’s flight was to
demonstrate the successful redesign of the shuttle’s fuel tank,
return the space station to full staff for the first time in
three years and repair the station’s mobile rail cart so that
assembly of the $100 billion complex can resume.

All goals were met, as well as a host of other objectives
including tests to repair shuttle heat shield damage and the
delivery of more than 2.5 tons of new equipment and supplies to
the outpost.

“Our (goals) won’t be completely accomplished until we have
the crew safely on the ground,” said flight director Tony
Ceccacci.

Touchdown at the Kennedy Space Center in Florida is
scheduled for 9:14 a.m. EDT (1314 GMT) Monday.

In addition to packing up their cabin for landing, the
Discovery astronauts on Saturday completed a second inspection
of their ship’s wings to check for damage from micrometeoroid
impacts.

Analysis was under way but so far engineers have seen
nothing to prevent Discovery’s planned touchdown on Monday.

NASA ordered extensive in-flight inspections as part of
$1.3 billion in safety upgrades since the Columbia disaster.

Inspections earlier in the flight, conducted with the same
cameras and sensors on a robot arm used during Saturday’s
survey, found no damage from launch debris impacts, such as
what triggered the breakup of Columbia and the deaths of seven
astronauts on February 1, 2003.

SMALL LEAK

The only problem nagging at NASA engineers is a small
chemical leak in one of the shuttle’s three power units used
during landing.

NASA plans to test the unit on Sunday and if the leak
worsens, it may be shut down, forcing the shuttle to land with
just two of the power units for the first time in the program’s
history.

While NASA said that would not be a problem, it would mean
explosive bolts instead of hydraulic power would be used to
release the shuttle’s landing gear so it can drop into position
for touchdown, deputy shuttle program manager John Shannon
said.

Also, to minimize risk, the space agency might decide to
land the shuttle at Edwards Air Force Base in California where
the weather is more stable and the landing area larger than at
the Kennedy Space Center.

NASA has said this mission was critical to the future of
the shuttle program as it tries to recover from the Columbia
accident.

Columbia’s wing heat shield was cracked during launch by
falling fuel tank foam but because there were no in-flight
inspections at the time, the damage went undetected.

Columbia disintegrated while returning to Earth 16 days
later when hot gases penetrated its structure.

NASA plans to fly 16 shuttle missions to complete the space
station. Its next flight is scheduled for launch around August
28.

(Additional reporting by Jeff Franks)