The Actual Dynamical Environment About Itokawa

The dynamical environment about and on Asteroid 25143 Itokawa is studied using the shape and rotation state model estimated during the close proximity phase of the Hayabusa mission to that asteroid. We first discuss the general gravitational properties of the shape model assuming a constant density. Next we discuss the actual dynamical environment about this body, both on the surface and in orbit, and consider the orbital dynamics of a Hayabusa-like spacecraft. Then we detail one of the approaches used to estimate the mass of the body, using optical and lidar imaging, during the close proximity phase. I. The Hayabusa Mission and Itokawa In the Fall of 2005 the Japanese Space Agency’s (JAXA) Hayabusa spacecraft had a rendezvous with Asteroid 25143 Itokawa (Fujiwara et al. 2006). In its subsequent mission it stayed in close proximity to the asteroid for three months, during which time it descend to the asteroid surface twice to acquire samples for eventual return back to Earth. Prior to these landings, the spacecraft made a number of trial descents to come close to the surface in order to test its navigation system. During this time period a precise shape model of the asteroid was constructed (Gaskell et al. 2006) which allows for detailed evaluation of the asteroid’s surface and close proximity dynamical environment. This shape model is presented in Fig. 1. During one of