An Sun oriented tether system capable of imparting a velocity change to a tumbling asteroid and deflecting it awayfrom an Earth impacting trajectory is considered. The tether system is composed of a balancing mass at its lowerend, and a net device at its upper end. The angular motion of the deployed tether system around the Sun issynchronized with the asteroid's so that the net device gently rendezvous and gets caught by it due to its tumblingmotion. The asteroid and the tether system are now connected together by the long Sun oriented tether and theasteroid's rotational motion creates tension in the tether and begins to pull the two objects closer together whilemaintaining Sun orientation by gravity gradient stabilization. This orbit modification maneuver changes the asteroid'sorbital period and causes it to develop a miss distance with Earth over time that reduces the likelihood of a collisionwith it a number of years later. The method is feasible for small to medium asteroid sizes with lead time of twodecades with currently available tether materials. The study identifies the required system sizing for a given range ofasteroid characteristics.
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