NASA aims
to launch four space shuttle missions by the end of the year, some aboard
different orbiters than originally planned, in order to continue assembly of
the International Space Station (ISS), mission managers reported late Monday.
The U.S. space agency released new launch targets for three ISS-bound missions in 2007
following the planned
June 8 liftoff of the Atlantis shuttle’s STS-117 station assembly flight. The
shuttle’s 11-day mission to deliver new solar arrays to the space station has
been delayed beyond its initial March 15 target following hail
damage to the orbiter’s foam-covered external tank.
“Once
Atlantis flies STS-117, it gets the ball rolling for everything else,” NASA
spokesperson Allard Beutel, of the space agency’s Washington D.C. headquarters,
told SPACE.com. “This is a chance to look a year ahead and get back on
track.”
Under the
new plan, set down during a Monday meeting of top NASA shuttle and ISS program
managers, Atlantis’ STS-117 mission will be followed by the Endeavour orbiter’s
STS-118 mission no earlier than Aug. 9.
The next
shuttle to fly will then be STS-120 aboard Discovery -- rather than the initially
planned Atlantis orbiter -- to launch the Harmony connector
node to the space station on Oct. 20. NASA then hopes to close out 2007
with a Dec. 6 launch of Atlantis on the STS-122 mission to deliver the European
Space Agency’s Columbus laboratory.
The
European-built module was initially slated to launch spaceward aboard NASA’s
Discovery orbiter, though the space agency reassigned some missions to
different spacecraft to ease shuttle processing and turnaround times, NASA officials
said.
“Basically,
it gave us a little more flexibility,” Beutel said of the shuttle swap for
upcoming spaceflights. “In a sense, it bought us some time back in the
processing time required.”
NASA also
set launch targets for the first two shuttle flights of 2008.
The space
shuttle Endeavour is slated to launch on Feb. 14, 2008 on the STS-123 mission
to deliver the Canadian-built
Dextre addition to the station’s robotic arm and the first of three station
segments that make up the Japan Aerospace Exploration Agency’s Kibo laboratory.
A second element of the Kibo module, as well as its own robotic arm, are due to
launch spaceward on April 24 on NASA’s STS-124 mission aboard the Discovery
orbiter, though the spaceflight was previously reserved for the Atlantis
orbiter.
NASA
shuttle and ISS managers have said that every orbiter flight in the outpost’s
assembly sequence through its projected 2010 completion date depends on the
success of the preceding orbiter flight. It also depends on international
contributions such as Russian Progress cargo ship launches, Soyuz missions to
swap station crews and the upcoming launch of Europe’s first Automated
Transfer Vehicle (ATV) supply ship.
“We’re in
such a position now where everything must line up, one after another, like
tumblers in a lock to get to the end of that sequence,” Beutel said.
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