An artist's concept of the Contour spacecraft. Photo: NASA

NASA's Comet Nucleus Tour, or CONTOUR, mission this month took a giant step closer to its launch when the project received approval to begin building the spacecraft.

Planned for a July 2002 launch, CONTOUR is expected to encounter Comet Encke in November 2003 and Comet Schwassmann-Wachmann-3 in June 2006. The mission has the flexibility to include a flyby of Comet d'Arrest in 2008 or an as-yet undiscovered comet, perhaps originating from beyond the orbit of Pluto. Such an unforeseen cometary visitor to the inner solar system, like Comet Hale-Bopp discovered in 1995, would present a rare opportunity to conduct a close-up examination of these mysterious, ancient objects which normally reside in the cold depths of interstellar space.

The nucleus of a comet is its heart, believed by scientists to be a tiny irregular chunk of ice and rock. To date only one comet nucleus has ever been viewed by a spacecraft: Comet Halley in 1986. CONTOUR will fly past at least two comets and take higher resolution images than those of Halley. It will also collect and analyze gas and dust to reveal the comet's makeup, greatly improving our knowledge of key characteristics of comet nuclei and providing an assessment of their diversity. CONTOUR also will clear up the many mysteries of how comets evolve as they approach the Sun and their ices begin to evaporate.

The CONTOUR spacecraft will fly by each comet at the peak of its activity when it's close to the Sun. During each encounter, the target comet will also be well situated in the night sky for astronomers worldwide to make concurrent observations from the ground. The spacecraft will fly by each comet at a distance of about 60 miles (100 kilometers).

After successful completion of both the Preliminary Design Review and an independent Confirmation Assessment and the Confirmation Review at NASA Headquarters, the comet flyby project is well on its way toward completing the spacecraft design. The CONTOUR mission is managed for NASA by the Johns Hopkins University Applied Physics Laboratory, in Laurel, MD. The Principal Investigator is Dr. Joseph Veverka of Cornell University, NY.