History of NEAR
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Click on image above to see the launch movie |
On February 17, 1996, the
Near Earth Asteroid Rendezvous (NEAR) Mission was launched on a Delta II rocket
to take the first ever close up look at an asteroid, 433 Eros. NEAR
was the first mission of NASA’s Discovery Program. Since NEAR, the Discovery
Program's idea of "faster, better, cheaper" planetary missions has expanded
with the launch of the Mars Pathfinder, Lunar Prospector, and many more. To study
Eros, NEAR
was equipped with a Multi-Spectral Imager, NEAR Infrared Spectrometer, X-Ray/Gamma-Ray
Spectrometer, Laser Rangefinder, Magnetometer, and a radio science experiment.
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Click on image above to see the Mathilde flyby movie |
After leaving the Earth's
gravity the NEAR spacecraft flew within 753 miles of the asteroid 253
Mathilde in June of 1997. Before NEAR's encounter with Eros, this was the
closest a spacecraft had ever been to an asteroid. The image to the left is a
mosaic of Mathilde taken during the flyby. C-type asteroids, like Mathilde, make
up 75% of all known asteroids. They are generally dark in color and found in the
outer part of the asteroid belt.
During the following month,
NEAR had its first deep
space maneuver in which it fired its engines to adjust the orbit so that the
NEAR spacecraft would make a close approach to Earth. In doing so, the spacecraft
took longer to get to Eros, but used a lot less fuel than if going there directly.
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Click on the image to see the Earth and Moon from NEAR's perspective as it flew by for a gravitational assist. |
In January of 1998, NEAR
flew by Earth to get a gravitational assist that would place NEAR in a direct
path to Eros. As NEAR approached Eros, the spacecraft tried to burn the engines
to slow down so that it would not pass by Eros. The burn
was automatically aborted, and the spacecraft started to tumble. In doing
so, the spacecraft lost communication for almost a day until it finally recovered
and corrected the tumbling. Due to the aborted burn, it was too late for the spacecraft
to slow down; therefore, the spacecraft flew by Eros on December 23, 1998 instead
of slowing down and starting the orbital phase of the mission. On January 3, 1999,
the spacecraft was slowed until it was just under the speed at which Eros orbits
the sun (2,017 mph). Finally, on February 14, 2000, the spacecraft entered
orbit around Eros. Summaries of these events can be found at the NEAR
News & Events web site.