The experimental DART spacecraft -short for Demonstration of Autonomous Rendezvous Technology- had moved to within 300 feet of the satellite orbiting 759km above Earth but ended its approach on Friday, the mission manager Jim Snoddy said on Saturday. 

The 800 pound computer-driven spacecraft was supposed to have maneuvered around the satellite, getting as close as 15 feet, for another 12 hours before disintegrating in orbit.

Mission orientated craft

"When we started doing precise maneuvers, we started seeing excessive propellant consumption," Snoddy said, 11 hours into the mission. 

"The mission as designed, when it runs out of gas, completes itself."

There were some navigation errors but no indication of a fuel leak, he said in a conference call. A Nasa investigation board will search for the cause of the problem.

Snoddy called the mission a partial success because it demonstrated that an entirely computer-controlled craft could find a satellite in space.

New experimental work

"We've done what nobody's ever tried to do before," he said. "A lot of things worked well on the ground. The real truth is you have to be perfect in space... There was obviously something we didn't model."

"A lot of things worked well...[but] there was obviously something we didn't model."

Jim Snoddy, Nasa mission manager

The $110 million mission, classified as high-risk because of its automated controls and low budget, was intended to help lay the groundwork for future projects like robotic delivery of cargo to space shuttles and automated docking and repair between spacecraft in orbit.

The company which built the craft, Orbital Sciences Corp, did not immediately return a call seeking a comment on Saturday.

The DART spacecraft was launched from an aircraft on Friday morning. The mission originated at Vandenberg Air Force Base and was managed by Nasa's Marshall Space Flight Center in Huntsville, Ala.

The Pentagon satellite that was the target of the mission was launched in 1999 and carries special reflectors that are used by guidance systems such as the one aboard DART.