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  • Dick writes about Earth and planetary science for Science magazine.
 

NEAR and Eros in an Eternal Embrace

12 February 2001 7:00 pm
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Close-up. The last image of Eros relayed by NEAR, showing an area 6 meters across, broke off after about three-fourths had been transmitted.

"The NEAR Shoemaker spacecraft is safely on the surface of Eros," Robert Farquhar proudly announced at 3:30 EST this afternoon. The NEAR (Near Earth Asteroid Rendezvous) mission director and controllers at the Johns Hopkins Applied Physics Laboratory in Laurel, Maryland, had just guided a half-ton spacecraft to such a gentle touchdown on the 33-kilometer asteroid Eros that the orbiter didn't miss a beat in its radio transmissions. The pictures returned just before touchdown revealed details on a centimeter scale that may help planetary scientists solve several mysteries about the asteroid.

The programmed descent of NEAR Shoemaker went without a hitch, even though the craft was never designed to contact anything. A single rocket fired at 10:31 a.m., sending the spacecraft toward the surface. Then four braking maneuvers in the final hour slowed it from 32 kilometers per hour to its touchdown speed, which was intended to be the pace of a slow jog. Still, the chance of survival was not much more than 1%, Farquhar said. Much to the surprise of all, a signal continued for at least half an hour after touchdown. "I think we can claim we soft-landed on the surface," Farquhar said.

The last image returned before contact shows a rocky, airless surface far different than that of the moon. Apollo astronauts drove around many a crater as deep as the day a meteorite gouged it out, but a fine, thick "soil," or regolith, covers the surface of Eros and has somehow ponded in small impact craters. And on Eros, boulders stick up through the regolith as if planted there rather than appearing to have fallen from a larger, nearby impact. If its last pictures help solve such mysteries, NEAR Shoemaker can rest in peace.

Related sites

NEAR's home page

A more accessible mirror site of NEAR's home page

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