“Suppose the asteroid is traveling 60,000 miles per hour. You want to make it 60,001.” Concerned by the possible 2036 impact of 99942 Apophis, two clever NASA astronauts have developed a tractor beam of sorts to pull asteroids off a possible collision course. Namely, send a relatively small (20-ton) ion-powered spacecraft to intercept and hover near the offending asteroid, and then let gravity work its mojo. “Even as the spacecraft counters the asteroid’s gravity, he said, its own gravity will pull the asteroid out of orbit.”