Team Readies for Final Attempts to Contact CONTOUR
13 Dec 2002
(Source: Johns Hopkins University Applied Physics Laboratory)
Mission operators are planning their final attempts to contact NASA's Comet Nucleus Tour (CONTOUR) spacecraft, which has been silent - and presumably inoperable - since August.
On Dec. 17 and Dec. 20 the CONTOUR team at the Johns Hopkins University Applied Physics Laboratory (APL) in Laurel, Md., will send commands through NASA's largest Deep Space Network antennas toward CONTOUR's assumed location nearly 42 million miles from Earth, instructing the probe to transmit through its multidirectional antenna.
"We know the chances of hearing from the spacecraft are very slim," says CONTOUR Project Manager Edward Reynolds, of APL, which manages the mission for NASA and built the CONTOUR spacecraft. "But we have an obligation to everyone who invested resources, energy and imagination in CONTOUR to try one last time."
CONTOUR, a NASA Discovery mission designed to provide the closest, most detailed look yet at a comet's nucleus, launched from Cape Canaveral Air Force Station, Fla., on July 3. On Aug. 15, after six weeks in a parking orbit around Earth, CONTOUR's STAR 30BP solid-propellant rocket motor was programmed to ignite at 4:49 a.m. EDT and boost the probe on a path toward Comet Encke. At the time, CONTOUR was about 140 miles above the Indian Ocean and out of radio contact with controllers. Mission operators expected to regain contact approximately 45 minutes later to confirm the burn, but Deep Space Network (DSN) antennas did not acquire a signal. Several attempts to contact CONTOUR in the weeks after the burn were unsuccessful.
Images from ground-based telescopes (http://spacewatch.lpl.arizona.edu/contour.html) taken Aug. 16-21 showed three objects very close to CONTOUR's expected path, leading team members to surmise that the spacecraft had broken apart near the end of the scheduled 50-second rocket burn. Though no direct observations of CONTOUR were made since, mission designers at APL and navigators at NASA's Jet Propulsion Laboratory used the August images to calculate the spacecraft's trajectory and estimate sizes of two of the three sections.
Next week the team will aim for the largest section, which they believe is CONTOUR's main body. Divided over both days the sessions should total about 16 hours, using the 34-meter and 70-meter antennas at DSN stations in Goldstone, Calif., and Madrid, Spain. CONTOUR is moving away from Earth at nearly 23,000 miles an hour.
"If CONTOUR's attitude is similar to when we last observed it, before the rocket burn, Earth will be near the center of the pancake antenna's beam width," says Mark Holdridge, CONTOUR mission operations manager at APL. "It's the best alignment of spacecraft and Earth since Aug. 15 and our best chance to make contact. The DSN receivers will be looking for any sign of life, so if CONTOUR is capable of sending a signal, we'll get it."
The Jet Propulsion Laboratory manages the DSN.
Investigation Update: Preliminary Report Scheduled for January
Work continues for the NASA-appointed team investigating the apparent loss of the CONTOUR spacecraft. The CONTOUR Mishap Investigation Board, led by NASA Chief Engineer Theron M. Bradley Jr., is expected to release its preliminary findings in January.