By Jonathan O’Callaghan NYTimes News Service
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If all goes to plan, in September 2022 a NASA spacecraft, the Double Asteroid Redirection Test mission, or DART, will slam into a space rock with the equivalent energy of 3 tons of TNT. The goal is to nudge the orbit of its target object ever so slightly, a practice run to see if we could divert an asteroid from a catastrophic impact with our planet in the future.