NASA will
try to launch the space shuttle Endeavour on July 11, nearly
a month late, after plugging a potentially dangerous hydrogen gas leak, top
mission managers said Wednesday.
Endeavour successfully
passed a leak check during a fueling test at its seaside Florida launch pad today,
setting
the stage for a planned 7:39 p.m. EDT (2339 GMT) liftoff toward the
International Space Station on July 11, said Mike Moses, who leads the shuttle's
mission management team.
NASA
initially tried to launch Endeavour on June 13, then again on June 17, but the hydrogen
gas leak in the shuttle's external fuel tank thwarted
both attempts.
Engineers pinpointed
the leak in a misaligned ground umbilical carrier plate (GUCP) on the tank. The
plate connects to a vent line that siphons excess hydrogen gas safely away from
the shuttle during fueling.
"This one I
feel really good about, that we've got that problem licked and we're not going
to see another GUCP leak again on the next launch attempt," Moses told
reporters.
Leak fix a success
Engineers replaced
a Teflon seal and realigned the problematic plate using special washers to plug
the leak, which did not reappear during today's fueling test at the Kennedy Space Center
in Cape Canaveral, Fla.
"Looks like the tank performed well," said Endeavour's
commander Mark Polansky via his Twitter page.
Polansky is leading a seven-astronaut crew tasked with
delivering the last piece of Japan's massive
Kibo laboratory to the International Space Station during a marathon 16-day
mission. It is NASA's third shuttle flight of the year, but the first to the
station since the outpost doubled
its crew size to six people last month.
NASA has strict
rules on the amount of hydrogen gas that can be near a space shuttle at launch
time because the extremely flammable gas can pose an explosion risk to the shuttle
and its astronaut crew.
During
fueling, the space shuttle's external tank is loaded with about 526,000 gallons
of super-cold liquid hydrogen and liquid oxygen. Some of that hydrogen boils
into gas over time and must be safely vented away from the shuttle and be
harmlessly burned off elsewhere.
Endeavour's
repaired tank passed today's test with flying colors, mission managers said.
"There
were absolutely no leak indications whatsoever noted on the two leak
detectors," said NASA launch director Pete Nickolenko. "We'll
continue to look at the data, and our next step is to move toward launch."
The Endeavour astronauts are slated to go into quarantine this
weekend and return to their Florida spaceport on Tuesday, Polansky said. The countdown
to Endeavour's July 11 launch will begin next Wednesday night, NASA officials said.
Atlantis window work
While one
team of engineers prepares Endeavour for launch, another is tackling
a window issue on the shuttle Atlantis.
During the
shuttle's May flight to the Hubble Space Telescope, a work light knob jammed up
against a flight deck window pane and dashboard panel. Initially the knob was
stuck fast, but engineers managed to remove it on Tuesday by pressurizing
Atlantis' cabin and applying dry ice on the knob.
Moses said technicians
plan to take a mold of the window to see if the knob has caused damage that
would require replacing the inner window, a potentially lengthy repair that could
sideline Atlantis for up to eight months.
The shuttle
is currently slated to launch supplies and parts to the International Space
Station on Nov. 12.
"It could
take a very long time, it sounds very scary," Moses said of any serious repair.
"But then again, I've learned this team is really good at re-sequencing and
coming up with some creative ways to do some work in parallel."
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