Uniformly Rotating Bodies: Asteroid 433 Eros

Abstract

The fundamental problem of orbital dynamics about small bodies is typified by the interaction of the spacecraft with a non-spherical body that is rotating uniformly in space. This was the problem presented to NASA’s Near Earth Asteroid Rendezvous (NEAR) mission when it had its rendezvous with asteroid 433 Eros. Eros has a highly irregular shape (see Fig. 1.5), is uniformly rotating about its maximum moment of inertia, and is massive enough so that solar radiation pressure and solar gravity play a relatively minor role in perturbing a spacecraft trajectory. Thus the analysis of this problem can restrict itself solely to the interaction of a spacecraft and uniformly rotating mass distribution. This chapter is based on an analysis performed prior to rendezvous with the asteroid in 2000, based on a model from a flyby of the asteroid in late 1998 [175] and also recounts some pre-mission planning analyses [154]. Thus, the gravity field values, total mass, and asteroid shape are not as accurate as currently available models, but making such changes will not alter the results and conclusions significantly. Detailed descriptions of the actual mission dynamics and Eros shape model are found in [107, 83].