Another Contour could be launched

After loss of spacecraft, scientists quickly plan new comet-probe mission

August 27, 2002|By Frank D. Roylance | Frank D. Roylance,SUN STAFF

Just 11 days after losing contact with NASA's Maryland-built Contour spacecraft, mission scientists said yesterday that they are drafting plans for a nearly identical, cut-rate effort to buzz the same two comets the first mission targeted.

"Should we not be able to recover Contour, we will proceed aggressively with Contour 2," said Cornell University's Joseph Veverka, the principal investigator on the $159 million mission. "We're planning to have another go at it."

Until a formal proposal is developed and submitted to the National Aeronautics and Space Administration, he said, it is pointless to speculate about how it might be received. NASA has one other comet mission in space and two more planned.

The first Contour (for Comet Nucleus Tour) spacecraft - designed and built at the Johns Hopkins University's Applied Physics Laboratory near Laurel - went silent Aug. 15 as its solid-fuel rocket fired to boost it out of Earth orbit.

Telescopic searches have found three objects streaking away from Earth on Contour's planned flight path, suggesting that the spacecraft has broken up.

Though they are still trying to contact it, controllers hold out little hope of success.

Veverka said 100 Contour team members at APL, and as many as 60 others in the United States and Europe, face job losses or career changes as a consequence of Contour's apparent failure.

If NASA decides to fund a second Contour mission, the new spacecraft could be launched as early as April 2006, scientists said.

It would carry instruments identical to those on board the first Contour and target the same two comets - Schwassmann-Wachmann 3 in 2006 and Encke the following year.

"We had selected them for specific scientific reasons," Veverka said. "Achieving the scientific goals is really important. ."

Contour was to have given scientists their closest look ever at the icy cores of two very different comets. Cameras and remote-sensing instruments might have returned clues to the conditions of the early solar system and to the origins of the water and organic matter that made life possible on Earth.

Project Manager Edward L. Reynolds said a replacement would cost much less than the $97 million spent to build the original spacecraft and its instruments and to develop its ground systems.

"There would be huge savings in not changing vast portions of the design," he said, suggesting the replacement's price tag might be as much as $20 million lower.

One component a new spacecraft would not carry is the solid-fuel rocket motor suspected as the cause of Contour's failure.

NASA has named an independent Contour Mishap Investigation Board to determine the cause of the failure. Its investigation is likely to focus on whether the Thiokol 30 rocket motor failed or somehow caused a malfunction because of heat or acceleration generated by the engine's thrust.

Mission director Robert Farquhar said the decision to drop the rocket from a Contour 2 design is dictated not by worries about its reliability but by orbital mechanics.

The rocket provided the extra energy the first Contour required to be able to loop repeatedly back to Earth to gather the added gravitational energy needed to reach its targets.

But the mission geometry will have changed by 2006, Farquhar said. "We wouldn't need it for a second mission because we don't have two comets in a row that require two return loops."

A new mission, he said, could reach the comets using Contour's maneuvering jets. But the change would also add unspecified costs for carrying additional hydrazine fuel and a more powerful Delta launch vehicle.

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