NASA unveils quartet of asteroid movies
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The longtime battering of Eros' surface has produced an amazing variety of landforms in which craters overlap each other, according to mission researchers. This NEAR Shoemaker image of asteroid Eros was taken April 5, 2000, from an orbital height of 66 miles (106 km)
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April 28, 2000
Web posted at: 12:37 p.m. EDT (1637 GMT)
From staff reports
LAUREL, Maryland (CNN) -- NASA this week debuted a four-part movie marathon of noir dramas centering on an asteroid more than 100 million miles from Earth.
NEAR Shoemaker should begin a new phase of its study of the
space rock Eros soon. It will descend to within 31 miles (50 km)
of the asteroid, the ideal orbiting distance
for its scientific investigation, mission researchers said.
The NASA robot ship obtained the series of flyover movies in March while
orbiting Eros from a distance of about 125 miles (200 km).
Its imager captured each part of the asteroid under changing
lighting conditions, highlighting lights and darks along
different surface features like gaping craters, fields of
boulders and a pronounced dip known as "the saddle."
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The first movie showcases one end of the asteroid pockmarked
by craters, sculpted by linear grooves and littered with
boulders about 50 meters (165 feet) across.
For the second, NEAR (Near Earth Asteroid Rendezvous)
Shoemaker trained its lens on the saddle, a part of Eros
that exhibits few impact craters. This relative smoothness
suggests the area's relative youth compared to other parts of
the asteroid, project scientist Andrew Cheng said.
The third sequence focuses on the 3.4-mile (5.5-km) diameter
crater that dominates one hemisphere on the asteroid. The
lighting in the crater's interior changes significantly
during the 1.5 hours of elapsed time in the movie, but the
brightness of the far wall remains constant.
"This type of behavior distinguishes real variations in
surface brightness from mere lighting effects," the NEAR
mission team said in a statement.
The finale blends together two stars of the earlier pieces. It
begins near the edge of the large crater in movie three and
travels to the middle of the saddle, which dominates the
opposite hemisphere in film two.
Approaching prime scientific orbit
A short engine burn on April 22 nudged NEAR Shoemaker from a
distance of 62-miles (100-km) toward its ideal scientific
orbit around Eros. It should reach that altitude on April
30.
All six of the spacecraft's instruments have been operating
for several weeks. But the laser rangefinder and X-ray gamma
ray spectrometer will work best from the closer orbit, according to mission scientists.
The performance of the other instruments should improve as well as
NEAR Shoemaker moves in closer to the 21-mile-long (34-km-long)
rotating space rock. Later in the year, the spacecraft could move in even closer and briefly touch down to conclude its primary mission, scientists said.
Currently, Eros and its artificial satellite are about 119
million miles (190 million km) from Earth.
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RELATED SITES:
NASA Homepage
Near Earth Asteroid Rendezvous Mission
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