This
article was updated at 7:05 p.m. EDT.
CAPE
CANAVERAL, Fla. - NASA's shuttle Discovery and its seven-astronaut crew will
have to wait at least a few more days to rocket into orbit after a last minute gas
leak prevented a Wednesday launch attempt.
Mission
managers called off Discovery's
launch attempt after detecting a leak of gaseous hydrogen in a line that
runs into the shuttle's attached external fuel tank. NASA is now targeting a launch for no earlier than March 15 at 7:43 p.m. EDT (2343 GMT). The extra time will allow engineers to take a look at the leak and make necessary repairs, mission managers said in a briefing after the launch attempt.
The leak
occurred in a gaseous hydrogen vent line that runs into Discovery's 15-story fuel
tank to keep its supply of liquid hydrogen propellant adequately pressurized. NASA space shuttles
use super-chilled liquid hydrogen propellant and liquid oxygen oxidizer to feed
their three main engines during launch.
NASA
officially scrubbed the launch plan at 2:37 p.m. EDT (1837 GMT). Discovery was
scheduled to lift off from the
seaside Pad 39A here at NASA's Kennedy Space Center at 9:20 p.m. EDT (0120
March 12 GMT).
"Teams
are going to get together and assess the repair options," said NASA
spokesman Allard Beutel.
The leak
was discovered at 2:15 p.m. EDT (1815 GMT), about two hours after ground crews
began filling the shuttle's massive orange external fuel tank. The problem
forced them to halt fueling immediately. Weather forecasts had predicted a pristine 95
percent chance of favorable flight conditions for tonight's launch attempt.
A new
delay
Wednesday's
launch delay is the latest in a series
of setbacks that have postponed Discovery's STS-119 mission for a month. The
shuttle was initially slated to launch on Feb. 12, but concerns with suspect
fuel control valves in the spacecraft's main engines prompted additional delays
so engineers could replace them.
Like the
leaky gas hydrogen line that thwarted Discovery's Wednesday launch, the shuttle's
three fuel control valves are also designed to maintain the proper pressure inside
the liquid hydrogen fuel reservoir of the orbiter's attached external tank. A
similar valve on the shuttle Endeavour cracked during a November 2008 launch
and NASA wanted to be sure a similar problem did not pose a risk to Discovery
and its crew.
Discovery's
valves were replaced twice, with mission managers deciding earlier this month
that the shuttle was fit to fly.
Commanded
by veteran shuttle flyer Lee Archambault, Discovery's
seven-astronaut crew will launch toward the International Space Station
carrying the outpost's final pair of U.S.-built solar wings and the last segment
of its backbone-like main truss. The
14-day mission will also ferry Japanese astronaut Koichi Wakata to the
station, where he will replace NASA astronaut Sandra Magnus as a member of the
orbiting lab's three-person crew. Wakata is Japan's first long-duration
astronaut and is due to return to Earth later this summer.
Set to
launch spaceward aboard Discovery with Archambault and Wakata are STS-119 pilot
Tony Antonelli and mission specialists Joseph Acaba, Steven Swanson, Richard
Arnold II and John Phillips.
Discovery's
two-week mission will mark NASA's first shuttle flight of the year.
If
Discovery is unable to launch Thursday, a third attempt is possible on Friday.
NASA has until March 17 to launch the shuttle before standing down due to a
previously scheduled Soyuz flight to ferry the new Expedition 19 crew to the
space station. If the shuttle cannot launch by March 17, NASA plans to stand
down until after the space station crew change, with the next launch window
opening on April 7.
SPACE.com
is providing continuous coverage of STS-119 with reporter Clara Moskowitz at
Cape Canaveral and senior editor Tariq Malik in New York. Click here for mission
updates and SPACE.com's live NASA TV video feed. Live launch coverage begins
at 4:00 p.m. EDT (2000 GMT).
advertisement
