CAPE CANAVERAL, Fla. - NASA's space shuttle Discovery is on track to
launch Wednesday evening to deliver new solar arrays to the International Space
Station, mission managers said.
Even the weather appears to be cooperating so far for
the planned launch from NASA's Kennedy Space Center at Cape Canaveral, Fla.
on March 11 at 9:20 p.m. EDT (0120 March 12 GMT).
"The weather looks good for launch, I'm very happy to say,"
NASA weather officer Kathy Winters said at a briefing here.
"We have these nice, mild conditions, warm temperatures... so a 90 percent
chance of 'go' weather."
The only possible threat to launch from weather could be from a ceiling
of clouds that may come in to block launch, Winters said. If that happens,
mission managers said they can attempt to launch every day up
until March 16, after which they would have to stand down to allow a
Russian Soyuz craft to make its scheduled flight to the space station.
Discovery's seven-man crew, led by commander Lee Archambault, arrived
in Florida yesterday on T-38 jets. They will spend today undergoing medical
exams, checking out their launch suits and reviewing launch plans. This evening
Archambault and shuttle pilot Tony Antonelli are scheduled to practice landing
the space shuttle by flying shuttle training aircraft, which are modified
Gulfstream planes.
Mission managers said Monday that no technical problems currently pose a
threat to Discovery's planned launch. They did investigate one minor worry
associated with a controller on the shuttle's Orbital Maneuvering System (OMS)
engines, which had had a "hiccup" during last year's May launch of
the shuttle Discovery's STS-124 flight. Ultimately, they decided it posed a
very low risk.
"If this part fails, it's one of two controllers on a single OMS
engine," said Mike Moses, chair of Discovery's mission management team,
adding that the controller was part of a tiered system full of backups. "So
redundancy-wise, we're in really great shape there."
After weeks
of delays to Discovery's launch date over fears that fuel control valves in
the shuttle's main engines might be faulty, NASA mission managers said they are
confident the shuttle is in good shape to fly.
"The team is anxious to go," said NASA shuttle launch
director Mike Leinbach. "We're fully trained, ready to execute this
mission."
Engineers ended up replacing the
three valves on Discovery with a set that had been scanned to be sure they
had no damage. Last year, a valve on NASA's shuttle Endeavour cracked during
its November 2008 launch. Though the problem didn't affect the shuttle's flight,
and Endeavour completed its mission successfully, mission managers wanted to be
sure a similar occurrence wouldn't endanger Discovery.
The valves monitor the pressure of liquid hydrogen fuel in the shuttle's
main engines during launch, and leak off excess gaseous hydrogen if needed.
After extensive tests, engineers found that even if a valve were to crack
during a future shuttle launch, the chances of it causing serious damage are
extremely low. Nonetheless, managers decided to replace Discovery's set of
valves with a new complement that were free of cracks even a fraction of a hair
wide.
Discovery is set for a 14-day mission featuring four spacewalks to
install the new solar array wings on the International Space Station (ISS). It
will also ferry up Koichi Wakata, a Japanese Space Exploration Agency (JAXA)
astronaut who is to become his country's first long-duration ISS crewmember. He
is scheduled to join the station's expedition 18 for about six months as a
flight engineer.
"I am expecting that this week will become a historic event for the
Japanese human space program," said Kuniaki Shiraki, JAXA ISS program
manager.
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.
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