Asteroid mission extended; encore flight scrubbed

Last image taken by NEAR before landing. The top panels magnify two mysterious depressions, each the size of a footprint

In this story: 'We have no fuel' Mysterious 'footprints' RELATED STORIES, SITES

Richard Stenger
CNN.com Writer

(CNN) -- The first spacecraft to land on an asteroid will make scientific observations on the surface of the space rock for at least 10 days, NASA announced Wednesday.

But mission engineers decided to ground the NEAR-Shoemaker probe permanently rather than command it make an encore flight, an option they considered after it made an improbable landing on Monday.

The robot ship touched down on the asteroid following a yearlong orbit, despite having no landing gear.

RESOURCES Web sites and recent CNN coverage of the mission     GALLERY View the best of Eros     MESSAGE BOARD Stargazing

"We were trying something untried in the history of deep space navigation," NEAR navigation chief Bobby Williams told reporters. "For a spacecraft not designed to land this came off extraordinarily well."

The NEAR (Near Earth Asteroid Rendezvous) mission was to shut down Wednesday, but NASA decided to give the probe a temporary reprieve after the ship sent radio messages to Earth after landing. Mission managers had considered such a feat almost impossible.

"It's sending back housekeeping data right now but we hope to get science data later this week," Williams said.

The probe probably landed tilted on its side, a stroke of luck that allowed it to continue communications with Earth, mission managers said.

'We have no fuel'

Moreover, its gamma-ray spectrometer faces the surface, which could allow it to collect invaluable data about the composition of the oddly shaped rock. There is a "reasonable chance" the data will be recovered, project scientist Andrew Cheng said.

Mission engineers had considered sending NEAR-Shoemaker on an encore flight, but decided not to because of its advantageous location for communications. There was another more compelling reason as well.

"We have no fuel on board, plus or minus 8 kilograms," said one NEAR scientist.

NEAR-Shoemaker traveled 2 billion miles (3.2 billion km) since it began its $225 million mission five years ago. During its yearlong orbit of Eros it took 160,000 pictures of the asteroid and conducted comprehensive studies of its geography and composition. Its rocky companion Eros is only the fifth celestial body touched by a human spacecraft, following the Moon, Mars, Venus and Jupiter.

Mysterious 'footprints'

Before its controlled crash into Eros, a 21-mile-long (34 km) object about 196 million miles (315 million km) from Earth, NEAR-Shoemaker beamed back pictures with the best resolution ever of an asteroid.

The images, one as close as 120 meters (394 feet), bring into focus features as small as a golf ball, said mission scientist Joseph Veverka.

Those and other NEAR pictures should keep astronomers busy for awhile. Some suggest unknown forces breaking up boulders, moving debris into flat crater pools and creating unidentifiable depressions the size of hand and footprints.

"We really have seen Eros in great detail. That has allowed us to answer a few questions, but also presented us with a bag full of mysteries that will have us scratching our heads for years to come," Veverka said.

Spacecraft makes improbable landing on asteroid
February 12, 2001
NASA hopes asteroid landing will solve riddles
February 9, 2001
Space probe swoops within 3 miles of asteroid
October 26, 2000
Asteroid orbiter marks halfway point in historic flight
August 16, 2000
Summer lets orbiter see asteroid Eros in new light
June 27, 2000
Asteroid Eros resembles 'building blocks' of Earth
May 31, 2000
NASA unveils quartet of asteroid movies
April 28, 2000
NASA releases first 'flyover movie' of asteroid
March 24, 2000
'Stunning' images hint asteroid broke from a planet
February 17, 2000
Comet co-discoverer Eugene Shoemaker dies in crash
July 18, 1997

Near Earth Asteroid Rendezvous Mission
Johns Hopkins University Applied Physics Laboratory
Near Earth Object Program
NASA

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