After a week of careful maneuvers, on July 13th the NEAR-Shoemaker spacecraft slipped into its tightest path yet around the asteroid 433 Eros. The new 17-hour polar orbit places the spacecraft 35 to 39 kilometers from Eros's center and at times carries it to within 20 km of its irregularly shaped surface. According to mission manager Robert Farquhar (JHU/Applied Physics Laboratory), the spacecraft could not remain in this unstable orbit indefinitely, and on July 24th the orbit radius will be raised back to 50 km.

NEAR-Shoemaker was placed at such close range to help three key scientific investigations. First, minute variations in the spacecraft's motion (as tracked by Doppler shifts in its radio signal) will reveal subtle differences in the asteroid's gravity field. The close passes will also allow the laser rangefinder onboard to make a detailed determination of the body's overall shape. Finally, a spectrometer will map gamma- and X-rays emitted from rock-forming elements like silicon, aluminum, iron, and magnesium -- data that will eventually yield a crude map of surface composition.

Farquhar notes that in late October mission controllers will maneuver NEAR-Shoemaker even closer to the asteroid, commanding it to dive inward for a two-orbit swoop to within 5 km of the surface. From that snug vantage the onboard camera should reveal surface features less than 1 meter across.