While efforts to locate the lost in space Comet Nucleus Tour (CONTOUR) spacecraft continued through the weekend, speculation has begun on what may have thrown the mission awry.
Over the last several days, a series of telescope, radar and radio checks were conducted in search of the probe.
Hope now centers on CONTOUR's built-in smarts to cycle through and broadcast over a set of onboard antennas.
That sequence -- lasting several hours -- was pre-programmed to start 96 hours after CONTOUR received its last command. That could mean ground controllers might hear from the probe as early as 4:09 a.m. Eastern Daylight Time (EDT) this morning, or as late as 10:09 p.m. EDT.
Photographic evidence
Those searching for CONTOUR were aided August 16 by the Spacewatch Project in Tucson, Arizona. Telescope imagery showed two objects along a path close to CONTOURs predicted trajectory.
Mission operators "know where to look now," said Robert Farquhar, CONTOUR mission director from the Johns Hopkins University Applied Physics Laboratory (APL).
"We arent sure that the spacecraft is completely gone, and thats what were going to be working on over the next several days," APL's Farquhar said.
APL built CONTOUR and is managing the mission for NASA. Total cost of the project is $159 million.
Using its 34-meter antennas, NASA's Deep Space Network stations are scanning the spacecraft's expected path beyond Earth's orbit, hoping to pick up radio signals from CONTOUR's transmitters.
Educated guesswork
Meanwhile, educated guesswork as to what happened to CONTOUR has begun.
One focus for troubleshooters is the CONTOUR STAR 30BP solid-propellant rocket motor and its mating to a cylinder called the Spacecraft Payload Attach Fitting (SPAF). Both the motor and the SPAF have flanges with an identical bolt hole pattern. Several dozen of these holes are aligned to mate the motor to the SPAF.
CONTOUR's mating with the STAR 30BP motor took place at the Kennedy Space Center, with the motor resting upright in its support stand. CONTOUR was then lowered onto the solid propellant engine - with great care required to align the holes in the two flanges. Once the spacecraft was resting on the motor in the support stand, bolts that join the elements were installed.
The fact that Spacewatch imaged two pieces of CONTOUR may provide an important clue, according to SPACE.com sources.
One possible scenario -- admittedly conjecture at this time -- is that the back end of the solid rocket motor blew out and the second piece is the motor nozzle/igniter assembly. The rest of the spacecraft could be relatively intact, with CONTOUR, perhaps, having been protected by the SPAF cylinder structure.
Using the STAR 30BP solid rocket motor to boost CONTOUR beyond Earth's gravity was a cost-reduction decision. Some $10 million in overall mission costs were saved in contrast to a more costly system that would have shoved the probe directly after launch into deep space.
CONTOUR is one of the econo-class -- cheaper, better, faster -- type of craft in NASA's Discovery-class line of space science missions.
Last contact with CONTOUR
After circling Earth since July 3, CONTOUR fired up its STAR 30BP solid-propellant rocket motor, with ignition programmed to occur at 4:49 a.m. EDT on Aug 15. That rocket blast would nudge the probe out of Earth parking orbit and onto a trajectory to encounter two comets over the next four years.
The craft would have been spinning at 60 revolutions per minute as the 50-second engine burn kicked CONTOUR into a solar orbit, where it would later intercept comets Encke in November 2003 and Schwassmann-Wachmann 3 in June 2006.
Clearly, the rocket motor did fire. Space surveillance radar found no traces of new debris in Earth orbit, the leftovers if, indeed, the comet-bound spacecraft had exploded.
However, mums the word from CONTOUR.
As the hours since last contact with CONTOUR now stretches into days, spacecraft managers, engineers, and scientists are increasingly worried the probe is truly lost to space.
advertisement
