‘Gravity Tractor’ Could Deflect Asteroids

A gravity tractor could deflect an Earth-threatening asteroid if it was deployed when the asteroid was more than one orbit away from the potential impact, according to a new study. If the space rock was found heading straight for Earth, a combination of techniques — including a gravity tractor — might save the day. The study, carried out by NASA’s Jet Propulsion Laboratory in Pasadena, California, shows that the weak gravitational pull of a nearby spacecraft could deflect a hypothetical asteroid 140 metres across, big enough to cause regional devastation if it hit Earth