NEAR TO DOUBLE-DIP WASHINGTON -- Scientists are beaming as the Near Asteroid Rendezvous (NEAR) probe slips ever closer to Asteroid 433 Eros.
Mission controllers have decided to perform a daring July maneuver that will drop the probe down to a risky sequence of low-altitude flyovers above the asteroid's battered surface.
The NASA probe -- now renamed NEAR Shoemaker after the late space geologist, Gene Shoemaker -- has settled into a 62-mile (100-kilometer) circular orbit around the potato-shaped, oddball world.
After a 5-second thruster burn on April 11, the probe nudged itself into the new orbit. The schedule calls for NEAR Shoemaker to stay in this asteroid-circling track for another week.
Engineers controlling the probe at the Applied Physics Laboratory (APL) in Laurel, Maryland, then plan to cut its altitude in half.
That maneuver will be followed in early July by yet another big dip in altitude, with the probe briefly zipping about the space rock at a daredevil distance of 20 miles (32 kilometers).
This practice run will prepare teams for end-of-mission maneuvers next February that might lead to landing the probe on Eros.
"We want to get a better handle on what the gravity field is like at that very low altitude," Andrew Cheng, APL project scientist told SPACE.com.
"The navigation team was not comfortable with the notion of going down for the first time during the last month of the mission," he said.
Controllers are working closely with space navigation experts at NASAs Jet Propulsion Laboratory in Pasadena, California.
A close-up of the surface of the Asteroid Eros.
Julys maneuver with the probe will be "like dipping your toe into the pool to see what the waters like," Cheng said.
Commands to push the spacecraft down to the lower altitude are to take place during the first week of July.
"By doing this now, the next time we drop down that far well have more confidence and know how to make sure the spacecraft ends up exactly where we want it to go," Cheng said.
Overall, NEAR Shoemaker is doing just great, said Robert Farquhar, mission manager at APL.
Fuel reserves aboard remain good since the probe began operations early this year on February 14 -- Valentines Day.
Because of Eros unusual shape and strange gravity field, the spacecraft is being pulled and tugged at different times during its orbit. Controllers are keeping a close eye on that to keep it from accidentally nosediving into the surface.
For now, Farquhar is maintaining a "What...me worry?" attitude, although the July maneuver is sure to be a little rough on his nerves.
"Thats getting pretty close," he said.
Science produced by the probe has been exceptional, Cheng said, declining to elaborate.
A series of reports are to be completed in the next few weeks. "Things should open up in a week once we get those papers in," he said.
The NEAR Shoemaker NASA probe.
Science teams are concentrating their observations on Eros' global fabric. They are looking at the extensive number of linear features, the makeup of curious white patches and whether the asteroid is covered in dust that might hide minerals underneath.
"Since there are a few dozen scientists working on the mission, the degree of consensus is minimal," Cheng said. "There are a lot of scientists and we dont all agree. So thats going to be fun."
Laser scans of the asteroids dark southern side suggest surprises in the offing, Cheng said.
"There are already indications of some very large features now in permanent shadow. We dont know what they are right now," he said.
Once the July maneuvers are completed, the probe will boosted to higher-altitude passes.
At the end of the year, it will in the right position to photograph the asteroids sunlit southern hemisphere. By missions end in February 2001, the entire rock of ages will have been surveyed.
Prospects look good for easing the probe down to a final resting spot on Eros.
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