near_regolith_001101 WASHINGTON -- Images taken during last week's low-altitude plunge toward Asteroid 433 Eros by the Near Earth Asteroid Rendezvous (NEAR) spacecraft show it has a thick carpet of regolith -- broken up, dirt-like material that covers the entire space rock.
NEAR swept by Eros on October 26 at just 4 miles (6.4 kilometers) distance, snapping several hundred images on the fly.
With the diving catch of data under its belt, NEAR has returned to a high-altitude orbit for a month to map the color properties of Eros' southern hemisphere. From early December until the end of its tour-of-duty in February 2001, the spacecraft is on its final stretch of relaying to Earth
high quality imagery of Eros and other science data. Footprints on Eros
"The flyover was incredibly successful from all points of view," said Mark Robinson, a NEAR science team member at Northwestern University in Evanston, Illinois. "It was a big first as far as navigating a spacecraft goes," he told SPACE.com.
NEAR spacecraft snapped this image, looking down the length of asteroid Eros' southern hemisphere.
Robinson is busy at work creating mosaics of Eros, carefully piecing together select NEAR photos taken over the last eight months.
Scientists were delighted at what has been revealed in the new closeup photos.
The most notable, Robinson said, is confirmation that a very thick regolith covers the whole of the asteroid. "It's
like the fine powder on the Moon. If you were standing on Eros, you would make a nice footprint," he said."You would have a hard time walking. It would be more like hopping, I think," Robinson said.
Scientists proposed 10 to 15 years ago that smaller asteroids couldn't have regolith because their gravity was too low, Robinson said. That surface material is clearly sticking to Eros.
"The gravity is weakbut it is there," Robinson said.
Buried boulders
NEAR pictures reveal other details too. The surface of Eros is a landscape littered with boulders and covered in regolith.
Inside the asteroids craters, there is slumping of regolith material. Boulders are partially buried in the dirt. The soil-like matter may top other surface rocks.
"One of the surprises, from my point of view," said Robinson, "is the somewhat lack of color variations on the asteroid's surface."
Boulders can be seen everywhere, from huge to small, said Louise Prockter, a NEAR science team member at The Johns Hopkins University Applied Physics Laboratory in Laurel, Maryland. "We've got a whole load of new, incredible images to look at," she said.
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