With less
than a day remaining before the launch of their autonomous spacecraft, NASA
researchers find themselves in an all-too-familiar position. But hopefully this
time it will be different.
Six months ago,
a series of glitches prevented NASA from launch its robotic DART spacecraft on
a mission to hunt down and rendezvous with an orbiting satellite. The space
agency, however, is ready to try again.
"The
excitement is back up to a fever pitch," said Jim Snoddy,
NASA's DART project manager, during a press conference held Thursday at the
mission's Vandenberg Air Force Base launch site in California. "Space weather
is about the only thing we're looking at for tomorrow's launch."
Researchers
attempted to launch DART, short for Demonstration of Autonomous Rendezvous
Technology, twice in late October 2004. But several problems, including poor
weather,
a contaminated
payload fairing and a communications glitch with DART's
target satellite, forced launch scrubs.
The mission
is now set to launch on April 15 between 1:21:49 and 1:28:49 p.m. EDT (1721:49
to 1728:49 GMT).
U.S. Air
Force Maj. Richard Benz, launch weather officer for the DART space shot, said
weather conditions are favorable for tomorrow's spaceflight, though another
launch window will be available on Sunday if needed.
Robot at the helm
DART has
been hailed as the first U.S.-built spacecraft designed to fly itself toward an in-orbit rendezvous with another space vehicle, though Russia has used the
technology for years to control its autonomous Progress cargo shipments to the
International Space Station (ISS).
The
European Space Agency (ESA) is developing its own unmanned autonomous
spacecraft - dubbed the Automated Transfer Vehicle - to loft cargo to the ISS,
as is the Japanese Aerospace Exploration Agency (JAXA). Earlier this week, the
U.S. Air Force also launched a small satellite, called XSS-11,
to demonstrate autonomous rendezvous functions.
According
to its flight plan, DART will spent about seven hours flying itself to the
Multiple Paths Beyond Line-of-Site Communications (MUBLCOM) satellite, which
has been in orbit since 1999. About 21 hours into the mission, DART should have
completed its rendezvous maneuvers and cast itself into a deorbit
trajectory that will destroy the autonomous spacecraft. The entire mission
should be over 25 hours after launch.
Instead of
lifting off from the ground, DART will get a boost before the engines of its
Orbital Sciences-built Pegasus XL rocket ever ignite. The spacecraft and its
four-stage rocket will be carried into launch position by the former passenger
jet Stargazer L-1011, which will fly to an altitude of about 40,000 feet
(12,192 meters) before unleashing its payload above the Pacific Ocean.
"We're looking forward to an uneventful
launch," said Bryan Baldwin, Pegasus launch vehicle program director for
Orbital Sciences, during the press briefing.
If
successful, DART's launch will be the second space
shot in two days for NASA.
The next
crew of the International Space Station (ISS), Expedition
11 commander Sergei Krikalev
and flight engineer John Phillips, is set to launch spaceward tonight
aboard a Soyuz rocket. The flight will also carry visiting astronaut Roberto Vittori,
who represents the European Space Agency. That launch is currently scheduled for
about 8:46 p.m. EDT (0046 April 15 GMT) this evening.
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