Scientists wait for errant space probe to make contact

A missing space probe has been found orbiting the sun but astronomers do not yet know if it is intact.

Astronomers at observatories in Arizona, California and Hawaii have captured pictures of the missing US$159 million ($345 million) space probe Contour, which has been silent since last week when it left Earth to embark on a years-long mission to visit at least two comets.

"It's orbiting the sun at this point," Dr Michael Buckley, a spokesman for Johns Hopkins University's Applied Physics Laboratory, said yesterday.

The university manages the mission for the National Aeronautics and Space Administration (Nasa).

The images confirm Contour fired its solid-propellant rocket motor as planned, but suggest something went awry, since they show two objects moving away from the Earth in tandem at 21,880km/h.

Mission members believe a portion of Contour broke off as it left Earth orbit. They assume the octagonal spacecraft remains largely intact, however, and are continuing to scan for a signal from it.

If no commands are received by the spacecraft for 96 hours, it is programmed to contact Earth. So far, nothing has been heard.

If the team does not hear from Contour, members will make a final effort to listen in December when the spacecraft's antennas are in a better orientation.

"We're obligated to give it this last try," Contour mission operations manager Mark Holdridge said. "And who knows, we might get lucky."

Meanwhile, Nasa is preparing to investigate the mishap.

Contour, short for Comet Nucleus Tour, was launched into Earth orbit on July 3. On Thursday, it fired its motor as programmed in a manoeuvre designed to send it looping around the sun.

Contour was supposed to signal operators at Johns Hopkins around 45 minutes after the rocket burn, but no signal arrived.

The Contour probe is scheduled to pass through the comet Encke on November 12, 2003, and the comet Schwassmann-Wachmann 3 on June 19, 2006, travelling within 100km of each comet's nucleus. Both comets are less than 50 million kilometres from Earth.

Nasa hopes that by analysing the comets close up, Contour will reveal the secrets of the hydrogen-rich celestial bodies, which could become mobile fuelling stops for future explorations.

Scientists also study comets because they believe each has a nucleus frozen around 4.6 billion years ago, as the planets were forming, and may contain clues about the beginning of life on Earth or the extinction of the dinosaurs.

today@Nasa.gov

Spaceflight Now

Stardome Observatory