CAPE CANAVERAL, Fla. - After a month of delays, the
beleaguered space shuttle Endeavour is aiming to lift off tonight toward the
International Space Station, but only if the weather cooperates.
Endeavour will make its third
launch attempt this evening at 7:39 p.m. EDT (2339 GMT) from the seaside
launch pad here at NASA's Kennedy Space Center. The shuttle's two earlier
efforts to blast off in mid-June were thwarted by a hydrogen gas leak that has
since been repaired.
The weather poses tonight's biggest
concern, NASA said, with only a 40 percent chance of favorable conditions for
launch. If thunderstorms and thick clouds hinder today's plans, NASA can try
again tomorrow or Monday, when the weather outlook is slightly better.
"We do have some challenges
with the weather, but we'll just work through those," said NASA's Mike
Moses, head of Endeavour's Mission Management Team, during a Friday briefing.
Endeavour's seven-astronaut
crew, led by commander Mark Polansky, plans to embark on a 16-day
construction mission to the space station. Set to launch with Polansky are
shuttle pilot Doug Hurley and mission specialists mission specialists David
Wolf, Chris Cassidy, Thomas Marshburn, all of NASA, and Canadian Space Agency
astronaut Julie Payette.
The astronauts plan an ambitious
schedule with five spacewalks and complex robotic work to install the final
segment of the Japanese Kibo laboratory and spare supplies on the station.
"We don't want to lose sight of
the complexity of this mission," Moses said. "It's going to be
unbelievably challenging."
The Kibo element - a large outdoor
platform for exposing science experiments to the space environment - will
complete the $1
billion Japanese facility.
"Kibo is the first manned space
system for the Japanese people, who are paying a lot of attention to this
flight," said Koki Oikawa, a member of the Kibo project team at the
Japanese Aerospace Exploration Agency (JAXA). "We can look at the complete
of the whole Kibo soon, so that's very exciting."
Six spaceflyers await Endeavour on
the space station, including Japanese astronaut Koichi Wakata, who is set to be
replaced by NASA astronaut Tim Kopra as an Expedition 20 flight engineer. The
station's current crew includes two Russian cosmonauts and one astronaut each
from the United States, Japan, Canada and Belgium.
When the shuttle arrives, the
International Space Station will be home to 13 people - its
highest population ever. The mission is also the first in which two
Canadians - Payette and astronaut Robert Thirsk - will be in space at the same
time. It also marks the flight of the 500th person, slated to be Cassidy, to
orbit.
Originally scheduled to launch June
13, Endeavour was kept on the ground twice before by a leak of gaseous hydrogen
from a vent pipe on its external fuel tank. Since then, NASA has conducted a
thorough investigation of the issue, and tracked the problem back to a
misaligned plate on the shuttle's 15-story external tank.
After successfully testing a fix
last week, mission managers said they're confident it won't pose a problem this
time.
SPACE.com is providing continuous
coverage of STS-127 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 2:30 p.m. EDT (1830 GMT).
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