A New Gravity Model for Navigation Close to Comets and Asteroids

What is it about?

Gravity models diverge when the spacecraft is inside a sphere of maximum radii. Point mass models are exact everywhere, but require too many point masses to be practical. The gravity model described in this paper performs the integration with respect to r analytically and integrates numerically over the surface of the body. It is exact in the limit as the integration intervals go to zero and is exact for variable density.

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Why is it important?

This is the model used to land on the asteroid Eros in 2001. This was the first successful landing on a small body and may be the last depending on the definition of success.