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This page contains recent press releases concerning discoveries and information about minor planets (asteroids) and related issues. The page will updated as and when time permits.
Burn puts NEAR Shoemaker in Ideal Science Observation Orbit
[http://near.jhuapl.edu/news/flash/00apr30_1.html]
On April 30, at 12:15 p.m., Eastern Daylight Time, the NEAR Shoemaker spacecraft successfully completed one of its largest orbit correction maneuvers to date. The hydrazine engine burn lasted approximately 2 minutes, 20 seconds and moved the spacecraft from a 62 X 31-mile (100 X 50 kilometer) orbit to a 31-mile circular orbit over Eros' north and south poles. This is the sixth time the spacecraft's thrusters have been fired to adjust its position since it began orbiting Eros on February 14, 2000.
The burn also successfully reduced spacecraft momentum buildup by slowing the four momentum wheels that spin faster and faster as the spacecraft works to stay sun pointing. If the momentum isn't reduced it can build to a level where the guidance system can't maintain control of the spacecraft so its autonomous systems send it into safe mode. To avoid this, momentum dumps are routinely conducted about every week to 10 days.
For the next two months the spacecraft will remain in a 31-mile orbit, giving the imager its closest view yet of the slowly tumbling asteroid and the Laser Rangefinder and X-Ray Gamma Ray Spectrometer instruments a chance to begin collecting data from a distance optimum for their design. All instruments are operational at this time.
The April 30 burn left NEAR Shoemaker travelling at 7 miles per hour-a reduction of 3 miles per hour from its previous speed. Although gravity is so slight that a baseball tossed from the surface of Eros would easily leave the asteroid's gravitational confines, there is still enough of a pull to influence the spacecraft's flight. A greater gravitational pull as the spacecraft comes closer to Eros and the closer proximity make it necessary for each engine burn to be increasingly more accurate. The next orbit correction maneuver is expected to take place July 7.
[Return to Index]The images of Eros being returned by NEAR Shoemaker reveal a surprising diversity of interesting features. Many people's preconceptions of asteroids come from cinematic special effects that depict asteroids as little more than oversized tumbling rocks, perhaps tattered by strange, jagged landforms.
This image, [http://near.jhuapl.edu/iod/20000420/index.html] taken April 17, 2000, from a distance of 101 kilometers (63 miles), suggests three words that could describe this asteroid: rocky, ridged, and rounded. The large boulder in the far left-center of the image measures more than 70 meters (230 feet) across. The ridge in the lower section of the frame is part of a feature that continues around a substantial part of the asteroid's middle. And although some of the small craters appear fresh and sharp, most of their rims have been rounded off by eons of relentless pounding by small, impacting meteors.
[Return to Index]One of the most striking features in NEAR Shoemaker images of Eros' surface is the abundance of very large boulders. This image [http://near.jhuapl.edu/iod/20000404/index.html] of the southwestern part of the saddle region, taken March 6, 2000, from a range of 201 kilometers (125 miles), shows a particularly boulder-rich part of the surface. Many of the huge rocks are 50 meters (164 feet) or more in diameter. They are believed to be fragments of Eros' native rock, shattered over the eons by formation of impact craters. The impacting projectiles themselves were pulverized by the impact process and survive only as fine debris mixed into the regolith.
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