Two NASA astronauts have figured out a way to create a real-life version of a "Star Wars" "tractor beam" to keep an asteroid from crashing into Earth.
By hovering nearby for perhaps a year, the astronauts say, the spacecraft's own gravity could minutely slow the asteroid's progress or speed it up, a process that 10 or 20 years later would cause the rogue rock to miss Earth by a comfortable margin.
"The beauty of this idea is that it's incredibly simple," said astrophysicist-astronaut Edward Lu. Since momentum does not dissipate in space, with enough time only a small early nudge is needed to cause a major orbital change.
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