Home > Antenna > Plan to save Earth from asteroid impact > Plan for a gravity tractor > Hovering craft 'A 20-tonne gravitational tractor hovering for one year can deflect a typical asteroid of about 200 m diameter given a lead time of about 20 years.' Ed Lu, astronaut, NASA No strings attached Page 3 of 5 How does the gravity tractor work? back to: Plan to save Earth from asteroid impact   Ed Lu, astronaut, NASA Image: NASA     Image: Dan Durda, FIAAA / B612 Foundation

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