CAPE
CANAVERAL, Fla. - NASA is poised to launch seven shuttle astronauts toward the
International Space Station (ISS) Tuesday on what some have called the most
ambitious orbital construction mission to date.
Commanded
by veteran spaceflyer Pamela Melroy, the shuttle Discovery is slated to
launch from Pad 39A here at NASA's Kennedy Space Center (KSC) at
11:38 a.m. EDT (1538 GMT). Melroy and her crewmates plan to swap out one ISS
crewmember, deliver an orbital hub to anchor future laboratories to the station
and perform the complicated move of a 17.5-ton solar array segment to boost the
outpost's power grid.
"I think,
by any measure, this will is one of the most challenging and audacious missions
of the shuttle era," said Discovery astronaut Scott Parazynski, lead
spacewalker for the NASA's STS-120 mission. "We're all very proud to serve and
be a part of this flight."
Set to
launch spaceward with Melroy and Parazynski are Discovery pilot George Zamka
and mission specialists Stephanie Wilson, Douglas Wheelock, Daniel Tani and
European Space Agency astronaut Paolo Nespoli. Together, they will install the
Italian-built Harmony node - the connecting point for European and
Japanese laboratories waiting to fly.
During five
planned spacewalks - the most-ever during a shuttle flight to the ISS - the
STS-120 astronauts will also test new space shuttle heat shield repair methods,
move the station's $276 million Port 6 (P6) solar power truss segment from its
mast-like perch to the station's port-most edge, and then unfurl its expansive
arrays. Parazynski compared the P6 relocation to moving an entire house from
one neighborhood to another.
"We hit the
jackpot, I won't kid ya. I think this is every astronaut's dream of a mission,"
Melroy said before launch day. "It's going to be an enormous challenge."
The flight will also be historic. Melroy, NASA's second
female shuttle commander, is set lead her crew into space to the
ISS, where veteran U.S. astronaut Peggy Whitson is serving as the orbital laboratory's first female
commander. Whitson and her Expedition 16 crewmates took charge of the space
station on Friday from its outgoing crew.
"The thing that is the best about this is that it happened totally by
accident," Melroy said. "Nobody planned it."
Tani will
replace NASA astronaut Clayton Anderson, who is currently living aboard the ISS
as an Expedition 16 flight engineer, during Discovery's spaceflight. He and his
crewmates hope to beat the weather for Tuesday's planned launch. Current
forecasts predict a 60 percent chance that rain showers and thick clouds could
prevent the planned space shot.
Gateway
to new labs, larger crews
Discovery's
STS-120 spaceflight will mark NASA's 120th shuttle flight to date
and the third mission this year to continue space station assembly.
But unlike
this summer's previous flights of the Atlantis and Endeavour orbiters - which
delivered new truss segments, cargo, spare parts and solar arrays - Discovery
is hauling up Harmony, which will increase the internal space of the ISS for
the first time since Russia's Pirs docking port arrived in 2001.
"Many
people look at it as the gateway to the international partner piece of the
space station," Derek Hassmann, NASA's lead ISS flight director during STS-120,
told SPACE.com.
Harmony
will serve as the anchor for the European Space Agency's Columbus laboratory - slated to launch aboard Atlantis in December - and Japan's
three-segment
Kibo laboratory. The new module will also hold quarters for ISS
astronauts once the station's crew complement doubled to six spaceflyers in
2009.
"It's very
exciting to think that the work we're doing is going to enable this exciting new
research and also enable a six-person crew capability in the future,"
Parazynski said.
While
Parazynski is making his fifth spaceflight with Discovery's planned launch
Tuesday, Zamka, Wheelock and Nespoli are making their first forays into orbit
during the STS-120 mission.
"I can't
wait for the clock to count down to zero and the solid rocket boosters ignite,"
said Zamka. "Because that will be a nice reminder that the training is over."
NASA
will begin broadcasting Discovery's STS-120 launch and mission operations live
on NASA TV at 6:30 a.m. EDT (1030 GMT) on Tuesday. Click here for SPACE.com's live launch
coverage, mission updates and NASA TV feed.
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