NASA pulls plug on trailblazing probe

Artist's concept of Deep Space 1

By Richard Stenger
CNN Sci-Tech

(CNN) -- After surviving long past its life expectancy and taking the best pictures ever of a comet, a NASA probe turned off its experimental engine at the behest of project managers.

Deep Space 1 roamed the heavens for three years using a propulsion system that could someday power robot ships on round trips to other planets.

But with its xenon gas fuel supply running perilously low, the craft was commanded to shut down its ion engine on Tuesday, having flown in space long past its original 11-month mission.

RESOURCES Message board: Space exploration

"I'm not sad it's ending. I'm happy it accomplished so much," said Marc Rayman, Deep Space 1 project manager at the Jet Propulsion Laboratory in Pasadena, California. "I think it inspired many people who saw the mission as NASA and JPL at our best -- bold, exciting, resourceful and productive."

The $160 million mission successfully tested one dozen experimental technologies, many of which could prove instrumental for future space probes.

A look inside the revolutionary ion engine

They include autonomous navigation software, whereby the spacecraft, with pictures of asteroids and stars taken by the onboard camera, plotted and corrected its course without the assistance of flight managers on Earth.

Another NASA mission in the works, the Deep Impact probe, will use the navigation system to reach the nucleus of comet Tempel 1, said JPL scientists.

Since taking flight in October 1998, Deep Space 1 barely weathered several storms. After an encounter with asteroid Braille, its star tracker failed to operate in late 1999.

Within months, mission engineers figured out a new navigation method to direct the probe, then 185 million miles (296 million kilometers) away. That allowed the probe the opportunity to fly by comet Borrelly this year.

The rocky nucleus of comet Borrelly

In September, the robot ship passed within 1,350 miles (2,160 kilometers) of the nucleus of the comet and took the highest resolution pictures ever of one of the primordial ice boulders.

"The daring flyby yielded new data and movies of the comet's nucleus that will revolutionize the study of comets," JPL said in a statement.

Although mission engineers transmitted their final farewells Tuesday, the resilient probe still clings to life. Basic systems were left on, meaning Deep Space 1 can keep its solar panels aimed at the sun and charge its batteries until the fuel supplies runs out, an event that could happen within months.

Just in case future generations want to make contact with Deep Space 1, which will remain in orbit around the sun for quite some time, mission engineers left its radio receiver on.