NEAR
Moves into Lower Orbit
3/6/00
A
thruster burn Friday afternoon put the Near-Earth Asteroid
Rendezvous (NEAR) spacecraft into a lower, circular orbit
that will give scientists their best look yet at the asteroid
Eros.
NEAR
fired its main engine for 22 seconds at 1 pm EST Friday, putting
the spacecraft into a circular orbit approximately 124 miles
from the center of Eros. NEAR has been in an elliptical orbit
since a thruster burn February 24.
NEAR
will spend the next four weeks in this new orbit, completing
three circuits of the asteroid. NEAR will begin "prime" science
data collection on March 5. During this time NEAR's multispectral
camera will take enough images of the asteroid to complete
the first global map of the asteroid. "We expect to resolve
a lot of the features that we've only seen glimpses of," said
NEAR imaging team member Louise Prockter.
Also
during March NEAR's laser rangefinder will begin to map the
topography of the asteroid. The rangefinder was tested for
the first time February 29, successfully bouncing a laser
beam off the asteroid at a distance of 180 miles, even though
the laser was designed to operate at an altitude of just 31
miles.
Scientists
will eventually combine the laser altimeter data with the images taken by the spacecraft to get a more complete, three-dimensional
understanding of the surface. The rangefinder data, for example,
will help scientists to determine if dark areas of the asteroid
are differences in color and thus composition, or just shadows
cast by other features.
NEAR's
X-ray spectrometer may also begin collecting data on the elemental
composition of the asteroid's surface, if the Sun cooperates.
"A lot depends on solar activity," said instrument scientist
Ralph McNutt. "If there is a strong solar X-ray event, the
instrument will get a good measurement."
Early
science results from the NEAR mission are expected to be released
in mid-March at a press conference during the Lunar and Planetary
Science Conference in Houston.
For
complete information on the mission, visit the NEAR
home page.
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