NASA Lands Probe on Asteroid

Feb. 12 -- After an apparently gentle descent, the first spacecraft ever to land on an asteroid touched down today shortly after 3 p.m. ET.

The 1,100-pound craft settled on a saddle-shaped depression of the asteroid, Eros, and then continued transmitting signals to Earth, suggesting it was not damaged as it struck the asteroid's rock-strewn surface.

Asteriod Landing Animation"I am happy to report that the NEAR has touched down," saidRobert Farquhar, the NEAR mission director, just after the craft transmitted its zero altitude location. "We are still getting signals!"

Not only was the dicey landing the first successful touchdown on an asteroid, it was also the most faraway landing ever attempted — at a distance of 196 million miles from Earth. The NEAR Shoemaker robot craft has no legs or landing gear and was never designed to land. To ensure a successful landing, controllers managed to slow the craft from about 20 to about 3 miles per hour.

First, controllers at The Johns Hopkins University Applied Physics Laboratory in Laurel, Md., triggered the craft to thrust its engines so the compact car-sized probe was knocked from its orbit and aimed for the asteroid. Then the team used a series of four rocket firings to slow the craft as it drifted toward the asteroid.

"We're right on the money," said NEAR Mission Operations Manager Robert Nelson as the NEAR probe drifted toward Eros. By just before 3 p.m. ET, the probe was less than a mile from the asteroid and approaching slowly. During its final descent scientists snapped about two photos of the asteroid every minute.

At one point controllers believed the craft had landed and then bounced away from the asteroid, but soon they received data suggesting it was resting on the rocky celestial outpost. The craft landed nearly on time, touching down on a 6-mile-wide, saddle-shaped depression at Eros' side at 3:07 p.m.

Risky Landing

"It's an exciting area geologically because we're on the edge of this large depression — which is probably a very large impact crater — and we'll be getting images of its interior as well as of the heavily cratered terrain on the outside," says NEAR imaging team member Mark Robinson of Northwestern University.