CAPE
CANAVERAL, Fla. - NASA mission managers today cleared the space shuttle Atlantis
for its planned Wednesday
liftoff and agreed to make three consecutive launch attempts before this
week is out.
"Everybody's
go," shuttle launch integration manager LeRoy Cain, who is leading Atlantis'
preflight Mission Management Team, told SPACE.com after a press briefing
here at NASA's Kennedy Space Center (KSC) spaceport.
Atlantis is
primed to launch its six-astronaut
crew toward the International
Space Station (ISS) at about 12:29 p.m. EDT (1629 GMT) on Sept. 6, with
current weather
forecasts predicting an 80 percent chance of favorable conditions. NASA's
window to launch the shuttle's STS-115
mission in daylight conditions, while avoiding conflicts with an upcoming
Russian Soyuz spacecraft's launch to the ISS, closes
on Sept. 8.
Mission
managers agreed to make three launch attempts in as many days - something tried
only once before in NASA's 25-year
shuttle history - to boost Atlantis and its cargo of new
solar arrays and a pair of 17.5-ton trusses to the ISS. The mission marks
the first major addition to the station since the STS-113 mission aboard
Endeavour in late
2002.
NASA launch
director Michael Leinbach said mission managers typically plan for four shuttle
attempts in five days, a process that allows up to a 95 percent chance
of a successful space shot.
"So three
in a row is probably in the low 90s," Leinbach said. "To a man, to a woman, there
were no disagreements at all about trying three in a row. We want to get this
vehicle into orbit."
Three
consecutive attempts to launch NASA's STS-101 mission in April 2000 were
prevented by poor weather, which is not anticipated for Atlantis' STS-115
mission. Clouds within 10 nautical miles of the launch site, and isolated
showers within 20 nautical miles of KSC's Shuttle Landing Facility are
currently the only threats to a Sept. 6 launch, shuttle weather officials said.
NASA hopes
to launch Atlantis under optimum daylight conditions to evaluate how modifications
to the shuttle's external tank affect a series of ice
frost ramps that are covered in foam insulation. Tank engineers are
drawing up new ice frost ramp modifications to curtail their amount of foam
insulation - a potential source of hazardous debris during launch - and are
expected to hit a final design near the end of this month.
Wayne Hale,
NASA's shuttle program manager, said that studies are underway to decide
whether the lighted restrictions for Atlantis' launch could be lifted if the shuttle
fails to lift off this week.
Atlantis'
STS-115 mission was originally set to be the first spaceflight to launch
without such restrictions since the 2003 Columbia accident, and
could launch in late September or early October if shuttle officials agree to
set aside the imposed daylight rules, Hale added.
The next daylight
opportunity to launch Atlantis is Oct. 26, NASA officials have said.
Any
substantial delay of Atlantis' ISS construction mission would add pressure to
additional missions downstream to complete
the orbital laboratory, Hale said, adding that it is imperative to resume
station assembly.
"I'm
extremely excited to be here because this is the purpose for which we fly,"
Hale said.
Atlantis' flight
preparations have been plagued by seasonal thunderstorms, a launch
pad lightning strike and a tropical depression - formerly Tropical
Storm Ernesto - which prevented the shuttle from rocketing spaceward last week.
Shuttle engineers and mission managers have since worked around the clock to prepare
Atlantis for launch before its lighted September window closed, though Leinbach
assured that nothing has been left to chance during that effort.
"We did not
cut any corners," Leinbach said. "We did not take any chance at all that, in
this turnaround process, we've missed anything."
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