Of the 12 advanced technologies onboard the spacecraft, seven have completed testing, including the ion propulsion system, solar array and new technologies in communications, microelectronics and spacecraft structures.

"We've taken these technologies around the test track, and now they're ready for the production line," said Dr. Marc Rayman, deputy mission manager and chief mission engineer for Deep Space 1 at NASA's Jet Propulsion Laboratory (JPL), Pasadena, CA.

Launched October 24, Deep Space 1 is the first mission under NASA's New Millennium Program, which features flight testing of new technology, rather than science, as its main focus. These new technologies will make spacecraft of the future smaller, cheaper, more reliable and more independent of human control.

By summer, engineers expect to have finished testing all 12 advanced technologies aboard the spacecraft.

Testing of two technologies that make the Deep Space 1 less reliant on humans is 75 percent complete, while testing of a third is scheduled to begin in May. These technologies include a robotic navigator, called AutoNav, that will guide the spacecraft to a rendezvous with asteroid 1992 KD on July 29 without active human control from the Earth.

In addition, Deep Space 1's two advanced science instruments -- a combination camera/spectrometer and an instrument that studies electrically charged particles emitted by the Sun and other sources -- are on schedule, having finished 75-percent of their tests.

"What has pleased us more than anything is how well the technologies have been working in general," Rayman said, noting that their performance is remarkably close to engineers' estimates developed before launch.

"Of course, everything hasn't worked perfectly on the first try," Rayman added. "If it had, it would mean that we had not been sufficiently aggressive in selecting the technologies. Diagnosing the behavior of the various technologies is a fundamental part of Deep Space 1's objective of enabling future space science missions."

When the ion propulsion system was first activated November 10, the engine shut itself off after 4-1/2 minutes, and engineers were unable to restart it later that day. During the next attempt two weeks later, however, the engine started up easily and has performed flawlessly since then, logging more than 1,300 hours of operation.

Engineers believe the problem was caused by a piece of grit stuck to high-voltage grids within the ion engine. The grit was later dislodged, they believe, when parts expanded and contracted as the ion engine was exposed alternately to sunlight and shade.

Engineers also discovered after launch that stray light enters the camera/spectrometer, resulting in streaks of light when pictures are taken with a long exposure. The streaks are a result of how the instrument was mounted on the spacecraft, Rayman said.

The camera should be able to take acceptable pictures when Deep Space 1 flies by asteroid 1992 KD this summer, because it will use short exposures.

Despite such glitches, the great majority of the advanced technologies have worked extremely well, according to Rayman. "Mission designers and scientists can now confidently use them on future missions," he said.

Deep Space 1 will continue testing technologies until its prime mission concludes on September 18. NASA is considering a possible extended mission that would take the spacecraft on flybys of two comets in 2001.

The Deep Space 1 mission is managed for NASA's Office of Space Science, Washington, DC, by JPL, a division of the California Institute of Technology, Pasadena, CA. Spectrum Astro Inc., Gilbert, AZ, was JPL's primary industrial partner in spacecraft development.