NEAR Shoemaker Senses Gravity of its Latest Assignment

NEAR Shoemaker has entered a new orbit around Eros that will yield even more spectacular high-resolution images and additional information on the asteroid’s elemental composition and gravity field.

A short engine burn at 11 p.m. EDT on July 13 set NEAR Shoemaker in a circular orbit just 22 miles (35 kilometers) from Eros’ center, giving the satellite its best view yet of the peanut-shaped asteroid. Before getting to the detailed photos and surface composition readings, the NEAR team will devote the first four days of the 10-day orbit refining its estimate of the asteroid’s gravity.

Using NEAR Shoemaker’s radio tracking equipment, the team will gather data it needs to design lower-altitude operations later in the mission, and learn more about Eros’ internal makeup. "We’re looking for variations in density from one part of the asteroid to another," says NEAR Project Scientist Andy Cheng. "It’s not entirely clear whether the density is uniform, so we have to get closer and look harder."

The spacecraft’s near-polar orbit will bring it as close as 12 miles (19 kilometers) from the ends of the rotating asteroid. Circling Eros at about 8 miles an hour, NEAR Shoemaker is 71 million miles (114 million kilometers) from Earth.