A Gravitational Tractor for Towing Planetoids
astro-ph/0509595 [abs, pdf] :
Title: A Gravitational Tractor for Towing Asteroids
Authors: Edward T. Lu, Stanley G. Love
Categories: astro-ph
Comments: 4 pages, 1 figure - to be published in Nature
We present a concept for a spacecraft that can controllably alter the trajectory of an Earth threatening asteroid using gravity as a towline. The spacecraft hovers near the asteroid with thrusters angled outward so the exhaust does not impinge on the surface. This deflection method is insensitive to the structure, surface properties, and rotation state of the asteroid.
http://arxiv.org/abs/astro-ph/0509595