SPACE.com -- Eros Close-Up Surprises Scientists

NEAR Successfully Skims Eros' Surface

NEAR's Diving Catch

NEAR Shoemaker on Course for a Close Encounter

Project Hera: Triple-header Asteroid Probe


	Eros Close-Up Surprises Scientists By Leonard David Senior Space Writer posted: 04:59 pm ET 27 October 2000

WASHINGTON -- Eros rocks

WASHINGTON -- Eros rocks with big- time boulders. Scientists got an eyeful of that thanks to an October 26 low-altitude flyby of Asteroid 433 Eros by the Near Earth Asteroid Rendezvous (NEAR) spacecraft.

The probe zipped by this rock of ages at just 4 miles (6.4 kilometers) distance at its closest approach.

Before and after NEAR Shoemaker's low-altitude flyover of Eros, the camera took image mosaics of known landmarks to accurately fix the spacecraft's location. This mosaic, the last such set of "optical navigation" images inbound to the asteroid, was taken in the early hours of October 26, 2000. It is shown here in simple cylindrical map projection, centered near the equator on the 180-degree longitude end of the asteroid.

The up-close-and-personal maneuver added more scientific data to an already highly successful mission. NEAR has been on duty, circling Eros since February 14.

Field of vision

"Its just marvelous," said Andrew Cheng, NEAR project scientist at The Johns Hopkins Universitys Applied Physics Laboratory (APL) in Laurel, Maryland. APL built and manages the NEAR spacecraft mission.

"The images are striking. We are seeing more detail in the boulders. There are not as many boulders as some people predicted. Its not a surface paved with boulders and they are not piled one on top of each other," Cheng told SPACE.com.

Scott Murchie, NEAR science team member, said that the spacecraft snapped 227 images during its low-altitude pass of Eros.

"Things went absolutely flawlessly. We got every single picture down. There was no missing data. It was dead-on," Murchie said.

Uncharted territory

Murchie said the photos show features down to about 4 feet (1.2 meters) across.

"The boulders are everywhere, and range in size and shapes. The variety of boulders is very intriguing. That diversity suggests theres interesting geology being recorded there in those boulders," Murchie said.

First-look facts show the surface is dominated by boulders instead of craters. Also caught in the pictures, Murchie said, is an apparent grain to the surface.

"The strategy we were using for the images worked perfectly. We got good exposures and the right amount of overlap," Murchie said.

Sifting through the images, then interpreting what is seen, will take some time.

"Its sort of typical when you get into uncharted territory. You answer some questions, and you bring up other questions that you had no idea to ask before," Murchie said.

Last hurrah

NEAR is en route to a safe and circular orbit around Eros. By late next week, the spacecraft is to plant itself into a 124-mile (200-kilometer) orbit, looping around the asteroid.

Robert Farquhar, mission director for NEAR at APL, said NEAR continues to chug along.

"Since weve been in orbit around Eros, the spacecraft has done everything weve asked it to do," Farquhar said.

Work is underway to plan for NEARs last hurrah. On February 12, ground controllers are to send NEAR down to a final resting spot on Eros.

Squeezing out the last gulps of fuel, NEAR is to conduct a "controlled descent" to the surface of the asteroid, relaying to Earth images once every minute, in real-time.

Considered a bonus task for a spacecraft that has dutifully performed its primary mission, the touchdown would bring to a close a yearlong study of Eros, setting the stage for future asteroid exploration.