Scientist Tasted Success, Now He Wants to Sample a Comet

The scientist who recycled an old spacecraft earlier this year for the first visit to a comet by a man-made device wants to bring part of a comet home next time.

Robert Farquhar of the Goddard Space Flight Center in Greenbelt, Md., has become something of a folk hero among fellow space scientists because of the rousing success of the encounter he arranged with comet Giacobini-Zinner this year. Farquhar is the man most credited with figuring out how to use the moon as a slingshot to whip an orbiting spacecraft out to Giacobini-Zinner.

In an interview Wednesday at the American Geophysical Union convention here, Farquhar said he has won considerable support within the National Aeronautics and Space Administration for a new plan to send a “family” of spaceships out to several comets and collect samples to be returned to Earth.

Farquhar believes his plan can be accomplished for about $200 million, less than 25% of the cost of a mission to Halley’s comet that scientists at NASA had promoted. That mission was scrapped because of its cost, leaving the United States as the only nation with a space program that is not sending a probe to Halley.

After it was scrapped, Farquhar and fellow scientists Fred Scarf of TRW and Edward Smith of the Jet Propulsion Laboratory came up with the proposal to recycle an existing craft and send it on to Giacobini-Zinner, a comet that passes Earth every 6 1/2 years. The mission made the United States the first nation to reach a comet.

The spacecraft sent back reams of data when it passed through the tail of Giacobini-Zinner on Sept. 11. Among other things, the mission showed an unexpected electromagnetic field around the comet.

Farquhar’s new plan involves the use of a “mother” spacecraft and at least two “daughters” that would collect samples from at least three comets.

“I don’t think it makes any sense unless you look at a family of comets” to collect samples from different targets, Farquhar said.

A wide range of scientific instruments would be placed aboard the “mother,” which would also serve as a navigational aid for the “daughters.” The “mother” would remain at a safe distance from the dusty nucleus of the comet, thus protecting the delicate instruments needed for the mission.

The “daughters” would be canisters that would collect samples on their surface as they passed near the nucleus of the comet.

All of the probes could be launched by a single rocket and travel as a family to at least three comets. If they could be launched by Nov. 19, 1992, they would reach comet D’Arrest in 1995, comet Honda-Mrkos-Pajdusakova in 1996 and Giacobini-Zinner in 1998.