Lost NASA Craft A Dud?

There is little hope of salvaging a $159 million comet-chasing spacecraft that broke apart Aug. 15, scientists said Monday while announcing their hope to launch a replacement as early as 2006.

The Contour spacecraft has been silent since it left Earth orbit to embark on a multiyear mission to visit at least two comets.

NASA had just recently found the missing spacecraft, thanks to a half-dozen telescope images that confirmed the silent probe was in orbit around the sun.

Telescope images indicate Contour broke into three pieces. That confirms the spacecraft fired its solid-propellant rocket motor as planned, but suggests it was destroyed in the process or soon after.

"We're not very optimistic about the chances of ever recovering Contour again, but we haven't given up," said Robert Farquhar, Contour mission director at Johns Hopkins University's Applied Physics Laboratory. The university built and manages the mission for NASA.

A replacement mission could be readied for launch by April 2006 at a cost $10 million to $20 million less than the original, members of the mission said.

Mission members had listened for a signal from Contour for nine days straight, but now will listen only once a week for about eight hours.

The mission will be declared a failure if they hear nothing by December, when the Earth will be in good view of one of Contour's antennas for two or three days.

Contour, short for Comet Nucleus Tour, was launched into Earth orbit on July 3. On Aug. 15, it fired its motor in a maneuver designed to send it looping around the sun. The mission plan called for Contour to meet up with comet Encke in 2003, Schwassman-Wachmann 3 in 2006 and perhaps comet d'Arrest in 2008.

NASA and the European Space Agency plan at least two missions to comets in the next two years.