Pasadena, Calif. ? NASA sought to regain contact with a $159 million spacecraft it lost in space Thursday, when the robotic probe was to have left Earth orbit on a journey to explore several comets.

The Contour spacecraft was supposed to automatically fire its solid-rocket motor at 1:49 a.m. PDT to boost itself out of the orbit, where it has been since its launch last month.

At the time, the octagonal spacecraft was about 140 miles above the Indian Ocean and was too close to Earth and moving too fast for NASA’s Deep Space Network of antennas to track.

The network was to have picked up a signal from Contour 48 minutes after the burn, as the spacecraft moved away from Earth. Instead, it vanished.

By late Thursday afternoon, the giant dish antennas in California, Australia and Spain continued to search for the spacecraft, alternately sending it commands and listening for a response. Nothing was heard from Contour short for Comet Nucleus Tour.

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.