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Scientists in NASA's Jet Propulsion Laboratory and the Johns Hopkins University Applied Physics Laboratory (APL) continue to monitor the skies for signs of the missing $159-million CONTOUR spacecraft. But with still no communication from the comet-hunting probe as of Tuesday afternoon, it is looking less and less likely that the mission can be saved.
Launched July 3, CONTOUR was designed to explore the centers of comets--the most numerous large bodies in the solar system--which formed billions of years ago as the planets were taking shape. Its itinerary included flybys within 100 kilometers of the comets Encke and Schwassmann-Wachmann3 (both members of Jupiter's family of comets) in 2003 and 2006, respectively. CONTOUR spent more than a month circling Earth and on August 15, the spacecraft's rocket motor was scheduled to fire and blast the probe out of our planet's orbit. But 45 minutes after the burn, an expected signal to NASA's Deep Space Network of radio antennas failed to arrive. Additional bad news came the following day when several observatories recorded telescope images showing two objects traveling along CONTOUR's predicted path--indications that the spacecraft may have broken in two. The scientists could not determine how big the objects were, however, so they remain hopeful that CONTOUR is largely intact. "We realize the possibilities are small, but we can't discount the idea that the spacecraft is still operable," Mission Director Robert Farquhar of the APL said late Monday. "We have to determine that before we give up."
If it is still operative, CONTOUR should be close to completing a 60-hour-long attempt to transmit a signal to Earth through three of its four antennas. This sequence is scheduled to begin 96 hours after CONTOUR receives its last command. But because it is unclear what commands the craft received late last week, the 96-hour period could have ended any time between 4:09 a.m. (EDT) and 10:09 p.m (EDT) on Monday. And even if CONTOUR is functioning properly, scientists on the ground may not know it. "It may be difficult to hear anything because, depending on the spacecraft's position and condition, the antennas might not have a direct line of sight toward Earth," says CONTOUR Mission Operations Manager Mark Holdridge. If no signal is detected by the end of the week, NASA plans to resume searching for the craft in late December, when its antennas may be more favorably positioned.