Radio science results during the NEAR-Shoemaker spacecraft rendezvous withEros

We determined the mass of asteroid 433 Eros, its lower order gravitational harmonics, and rotation state, using ground-based Doppler and range trackin g of the Near Earth Asteroid Rendezvous (NEAR)-Shoemaker spacecraft and ima ges of the asteroid's surface Landmarks. The mass of Eros is (6.687 +/- 0.0 03) x 10(18) grams, which, coupled with our volume estimate, implies a bulk density of 2.67 +/- 0.03 grams per cubic centimeter. The asteroid appears to have a uniform density distribution. The right ascension and declination of the rotation pole are 11.37 +/- 0.05 and 17.22 +/- 0.05 degrees, respec tively, and at Least over the short term, the rotation state of Eros is sta ble with no measurable free precession of the spin pole. Escape velocities on the surface vary from 3.1 to 17.2 meters per second. The dynamical envir onment of Eros suggests that it is covered with regolith and that one might expect material transport. toward the deepest potential wells in the saddl e and 5.5-kilometer crater regions.