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- LAUREL, Maryland (CNN) --
Poring over unprecedented close-up images of asteroid Eros, including the
first one in color, NASA scientists on Thursday speculated that the space
rock may have broken off from a small planet eons ago.
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- Only days into its yearlong orbit around Eros, the NASA
robot ship has snapped asteroid pictures of unrivaled clarity, presenting
a haunting panorama of boulders, bright spots and craters on the potato-shaped
rock.
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- Collected by the Near Earth Rendezvous spacecraft, some
of the images show signs of geological layering, which suggests that Eros
was once part of a much larger celestial body, said Andrew Cheng, a NEAR
project scientist.
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- "A plausible way that it (layering) happened is
if Eros was once part of a larger body," Cheng said, "probably
a planet-sized body that once broke up."
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- The parent object was most likely smaller than the Earth's
moon, he said.
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- The preliminary images from NEAR offer a close-up look
at complex surface features, including six or seven boulders, some the
size of soccer fields and one that seems to have rolled into a crater.
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- "I was stunned, speechless, by the beauty of this
asteroidal landscape," project scientist Mark Robinson told reporters.
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- Gravity on Eros is only about one thousandth of that
on Earth. A human could easily jump off the surface. Yet the gravity on
the asteroid seems strong enough to make boulders roll downhill, NEAR scientists
said.
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- The boulders "give us natural drill holes"
that could enable future missions to answer questions about the interior
of the asteroid, Robinson said.
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- Other mysterious features include a white spot 25 times
brighter than other parts of surface, which indicates it could have a different
mineral composition than rest of the asteroid.
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- And the surface of a saddle-like feature is smooth, meaning
it could be much younger than the rest of the asteroid. Most of Eros' surface
is pockmarked by crater impacts.
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- The density of Eros is about the same as the Earth's
crust. In contrast, Mathilde, an asteroid that NEAR zoomed by during its
four-year trip from Earth, was hardly denser than water, said NEAR mission
member Donald Yeomans.
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- The first color picture of the asteroid shows a slight
butterscotch hue, consistent with the variety of minerals thought to compose
Eros.
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- The first infrared images show an unusual concentration
of colors in the two "noses" of the asteroid, now 160 million
miles (250 kilometers) from Earth.
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- 'We don't know what it all means' "We're very excited
by all this, but we don't know what it all means. What's coming over the
next year, we can't even imagine," Robinson said.
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- NEAR began orbiting Eros from slightly more than 200
miles (300 kilometers) on Monday. But as the mission continues, it will
move progressively closer to the asteroid and perhaps land briefly, project
scientists said.
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- But orbiting Eros, which moves in an eccentric orbit
like a tumbling potato, can be "very tricky," said Yeomans. NEAR
could smack into asteroid or escape out into deep space if the craft experiences
flight trouble, he said.
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- While Eros itself poses no threat to Earth, scientists
hope the $224 million mission will determine the asteroid's origin and
offer clues about how to protect Earth from catastrophic collisions with
other large space rocks.
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- Built and managed by The Johns Hopkins University Applied
Physics Laboratory in Laurel, Maryland, NEAR was the first spacecraft launched
in NASA's Discovery Program of low-cost, small-scale planetary missions.
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