NASA’s Double Asteroid Redirection Test (DART) spacecraft is set to slam into an asteroid on Monday (Sept. 26), in the first ever test of humanity’s ability to deflect life-threatening asteroids before they collide with Earth. 

The 1,210-pound (550 kilograms) DART craft, a squat cube-shaped probe consisting of sensors, an antenna, an ion thruster and two 28-foot-long (8.5 meters) solar arrays, is set to smash into the asteroid Dimorphos while traveling at roughly 13,420 mph (21,160 km/h). 

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