The $159 million mission was designed and is operated by the Applied Physics Laboratory (APL) of Johns Hopkins University. The craft would explore two and possibly three comets to provide valuable clues about the range of compositions in these primordial, frozen objects.
Mike Buckley, a spokesperson at APL, said amateurs and professionals have been spotting CONTOUR (Comet Nucleus Tour) since its launch July 3.
It's possible, Buckley said, that one of them might spot the craft and solve the mystery of its location. Meanwhile, the Deep Space Network of ground-based radio telescopes is listening for any signal CONTOUR might send.
Since launch, the spacecraft has been on a highly elliptical orbit around Earth.
The cost-saving plan was to boost it into space using an onboard Star 30 solid rocket motor this morning. The approach shaved $10 million off the cost of the mission, compared to a plan that would have shot the craft directly from launch to deep space. Buckley told SPACE.com there are two scenarios for what might have gone wrong:
- The spacecraft's transmitter might have switched itself off
- The course-changing rocket might have damaged or destroyed the spacecraft
If the transmitter is down but the spacecraft is healthy and still in orbit, controllers would have one last chance late Friday to do a burn before the mechanics of it are impossible.
The spacecraft was about 140 miles above the Indian Ocean when the burn was slated to occur. CONTOUR was scheduled to report to ground controllers via the Deep Space Network at 5:30 a.m.
If CONTOUR is lost,
new target comets would probably have to be chosen for any possible replacement mission. Such a mission would not likely get off the ground within five years.This is not the first time that an Applied Physics Laboratory (APL) spacecraft has gone off line.
En route to asteroid Eros, the first rendezvous burn of the APL's Near Earth Asteroid Rendezvous (NEAR) spacecraft's bipropellant engine was not completed as planned on December 20, 1998.
Except for brief communication shortly after the scheduled 20-minute burn period, contact with the spacecraft was lost. Mission Operations swung into action trying to reestablish communication with NEAR based on expectations that the craft entered safe mode after its self-aborted engine burn.
An investigation into the mishap could not identify the exact cause of the engine abort. It was later determined that NEAR had gone through wild gyrations, spitting out loads of onboard fuel. A key onboard camera was contaminated with the spewed out propellant. Speculation is that a mismatch between computer software and main engine thrust sensors may have caused the problem.
Around-the-clock worry sessions led to reestablishing contact with NEAR on December 22. NASA's Deep Space Network verified a positive lock on a radio signal from the asteroid-bound spacecraft.
However, the craft missed its first chance to orbit Eros. Fortunately, NEAR was maneuvered in such a way as to re-rendezvous with Eros in February 2000. NEAR was able to complete a highly successful reconnaissance of Eros for a full year, then landed on the asteroid February 12, 2001.
Meanwhile, panic has not set in regarding CONTOUR.
Steven Squyres, an astronomer at Cornell University who is part of the CONTOUR science team, happens to be at JPL today for another matter. After a visit to Building 230 where the Deep Space Network team is searching for the spacecraft, he expressed confidence that it will be found.
"Nobody is running around here. There's no panic," Squyres said via telephone this afternoon. "They're working their way through their job."
Squyres explained that if the burn occurred as planned, the spacecraft "is now streaking across the sky. That makes it a very difficult target for the DSN to find. I'm not concerned in the least."
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