Boulders or big dirt piles? Still dust or shifting particles? The NEAR team hopes the high-resolution pictures NEAR Shoemaker sends back from its current 22-mile (35 kilometer) orbit around Eros can answer the range of questions they have about the asteroid's surface.

The closest view yet of Eros. This picture was taken July 8 from an orbital altitude of 22 miles. Photo: JHU/APL

"This is the closest we've ever been, giving us a more detailed view of Eros than we've ever had," says NEAR Project Scientist Andy Cheng of the Applied Physics Laboratory. "We're very interested in getting a closer look at the size and shape of the boulders, the texture of the surface, and finding out whether the regolith -- the layer of dust -- is moving across the surface."

Since completing a four-day gravity experiment on July 17 -- and gathering critical data for designing low-altitude maneuvers later in the mission -- the NEAR team has shifted its attention to imaging and other scientific activities. Though 22 miles from the center of Eros, the orbit actually brings NEAR Shoemaker anywhere from 12 to 18 miles (19 to 30 kilometers) from the asteroid's surface, which is prime positioning for the X-ray/gamma-ray spectrometer to analyze Eros' elemental composition.

NEAR Shoemaker could also be close enough for its magnetometer to detect a magnetic field from Eros -- should the asteroid have one. "The solar wind carries its own magnetic field, which reflects the magnetic field at the surface of the sun where the wind originated," says magnetometer instrument scientist Brian Anderson of the Applied Physics Laboratory. "Because the sun rotates and because of solar magnetic activity, the solar wind magnetic field is quite variable in space. Our challenge is trying to detect a possible Eros magnetic signature against the variable background of the solar wind field."

The spacecraft will keep its current position until July 24, when a short engine burn will send it back toward an orbit 31 miles (50 kilometers) from the Eros. By then, NEAR Shoemaker will have circled Eros 14 times in its current orbit.