NASA's $159 million Contour spacecraft apparently broke into at least two pieces during the firing of its onboard rocket motor last Thursday. On Friday, close to the predicted position of the spacecraft, at some 460,000 kilometers from Earth, the Spacewatch telescope near Tucson, Arizona, detected two objects, about 460 kilometers apart. "We aren't sure that the spacecraft is completely gone," says mission director Robert Farquhar of the Johns Hopkins University Applied Physics Laboratory in Laurel, Maryland, "but this is not very encouraging."
Contour (for Comet Nucleus Tour) was launched into Earth orbit on 3 July. The rocket burn of 15 August should have put the spacecraft on a trajectory to comets Encke and Schwassmann-Wachmann 3. Astronomers hoped that high-resolution close-ups of the nuclei of the two comets would shed light on the diversity of these small, frozen remnants of the solar system's birth. The rocket maneuver took place out of sight of NASA's Deep Space Network antennas. Some 45 minutes later, when Contour's signal should have been picked up, the screens at mission control stayed black.
Unless mission operators succeed in reestablishing radio contact with Contour, the true cause of the break-up may never be learned. Contour is programmed to send a signal back to Earth if it doesn't hear anything from mission control for 96 hours--that could happen as late as 10:09 p.m. EDT Monday. According to Farquhar, the rocket burn maneuver "was not considered to be very risky." A replacement mission could be proposed in NASA's Discovery program, but that would take at least a couple of years.
"The loss of Contour would be a basic setback for the near future of cometary science," says Gerhard Schwehm of the European Space Research and Technology Centre in Noordwijk, the Netherlands, who is the project scientist for the European Rosetta mission to comet Wirtanen, due to be launched on 13 January 2003. However, Schwehm says the bigger impact might be a loss of confidence in NASA's fast, cheap "Discovery-class" missions of which Contour is the sixth. Earlier Discovery missions also encountered technical mishaps--although none this serious.