HOUSTON - When NASA's space shuttle Atlantis launches
toward the International
Space Station (ISS) this month, it will kick off an increasingly complex
set of missions to complete the orbital laboratory, agency officials said
Friday.
Slated to
launch toward the ISS on Aug. 27, Atlantis and its STS-115
astronaut crew will haul a 17.5-ton addition to the space station's main
truss and two
new solar wings to double power production.
"It's great to be back flying an assembly mission," said STS-115 lead shuttle
flight director Paul Dye during a press briefing here at NASA's Johnson Space Center today. "We've flown a couple of test flights where we've proven the
shuttle's back and flies well. Now we're going to get back to the business of expanding
the space station and that's very exciting."
Atlantis'
STS-115 spaceflight will mark NASA's first dedicated ISS construction mission
since late
2002. The orbital construction work stalled after the 2003 loss of NASA's Columbia orbiter
and its seven-astronaut crew, which grounded the space agency's fleet for more
than two years while engineers developed new safety modifications. Since then,
NASA's Discovery orbiter has flown two test flights to shakedown
those enhancements.
With
Atlantis' upcoming mission NASA is poised to resume an at least 15-shuttle
flight sequence to complete the ISS by the orbiter fleet's 2010 retirement.
"You can
imagine that in 18 shuttle flights, that's going to be a busy period for the
program," said ISS program manager Michael Sufferdini, including NASA's recent STS-121
mission and two reserve flights into his construction mission count. "But
it's why we're here and we're looking forward to the challenge."
A tricky
mission
At nearly 35,000
pounds (15,875 kilograms), Atlantis' truss and solar array cargo is by
far the heaviest ISS element to ride in an orbiter cargo bay to date. It is designed to
generate about 20 kilowatts - about one-fourth of the station's power needs -
or enough electricity to support about six average homes.
Installing
the $371.8-million truss segment, connecting its power and data lines to the
ISS, and deploying its twin solar arrays on the station's port side will
require no less than three spacewalks by two teams of STS-115 astronauts.
To ensure a
successful construction job, spacewalkers must work smoothly with flight
controllers and engineers on Earth, as well as their fellow crewmates inside
the ISS and Atlantis.
"These are
extremely intense, extremely tightly choreographed missions," NASA mission
operations representative Phil Engelauf said. "Probably more so than we've done
in the past."
The
first of many
NASA's STS-115
mission is just the start of an ambitious plan to complete the ISS.
It will
take one more shuttle flight - STS-116 aboard Discovery set to launch on Dec.
14 - to bring the station's new solar arrays online, then two more spaceflights
to deliver two additional massive power modules to the orbital lab. A fourth
solar array is already aboard the ISS, but will have to be moved into its final
position during an upcoming shuttle flight.
Once all
four solar arrays are in place and functioning, the real heavy lifting begins
to launch long-waiting modules and international laboratories toward the
outpost.
"There is
very little wiggle room," Sufferdini said the ISS assembly plan. "Over the next
four years, every flight is very full, very busy."
But despite
the daunting path that lies ahead, station managers are confident they will hit
their target.
"We have prepared
long and hard for this," Sufferdini said of the road ahead for the ISS. "This
is what we've been planning for, this is what we've trained for, so we're ready
to go do this assembly task."
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