NASA Again Poised to Launch Autonomous DART Spacecraft
DART pulls up to Multiple beam Beyond Line-of-sight Communications (MUBLCOM) satellite. Built to test automated rendezvous technology, DART expertise should also prove helpful in latching rocket motor to Hubble Space Telescope as part of de-orbiting plan for the huge observatory.
Credit: OSC

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.