Why NASA's DART Mission Will Slam a Spacecraft Into an Asteroid

By Ramin Skibba

NASA is about to launch a craft designed to crash itself directly into a hurtling space rock at 15,000 mph.

If weather cooperates, NASA’s Double Asteroid Redirection Test mission, known as DART, will blast off early Wednesday morning atop a SpaceX Falcon 9 rocket at Vandenberg Space Force Base, northwest of Santa Barbara, California. DART will target a small near-Earth asteroid called Dimorphos, which is orbiting a much larger asteroid. Next fall, after a journey of some 6.8 million miles, the craft will smash into Dimorphos and slightly change the rock’s trajectory. It’s a test of what could be done to save the world from an asteroid on a potentially deadly collision course with us, to prevent the kind of planetary catastrophe envisioned in movies like Armageddon and Deep Impact.

The launch window opens at 1:21 am Eastern time on November 24, and the takeoff will be streamed on NASA TV. A cold front is approaching near the area, with some light winds, but officials still estimate a 90 percent chance of launch-friendly conditions, said Captain Maximillian Rush, a weather officer at Vandenberg Space Force Base, at a news briefing on Monday. If they have to delay for a day, he expects a 100 percent chance the weather will cooperate on Thursday.

“DART is the first mission devoted to planetary defense, to do something about an asteroid threat, to prevent it from hitting the Earth if you needed to,” says Nancy Chabot, the DART coordination lead and a planetary scientist at Johns Hopkins University’s Applied Physics Laboratory, which developed the craft in partnership with NASA. Dimorphos and the larger asteroid it orbits are not a threat, she quickly adds. “This is just a test.”

And DART has only one shot at it. The spacecraft’s basically a box, 4 feet across, with long solar panels on each side, and it needs a direct hit on Dimorphos, which is itself approximately 500 feet wide—about the size of the Great Pyramid of Giza. From Earth, the asteroid pair looks like a single faint dot in the sky. As DART careens toward them, its optical camera will feed images to the onboard Smart Nav guidance system. That includes an algorithm that automatically navigates the craft, rather than depending on commands from engineers on Earth, because there’s too much lag time over such long distances.

As it approaches, scientists will get a better idea of DART’s estimated date of impact, likely between September 26 and October 1 next year. About 10 days before arrival, it will deploy a briefcase-sized CubeSat called LICIACube, developed by the Italian Space Agency, which will snap photos of the cosmic collision and the resulting rocky debris, and send the images home.

Illustration of NASA’s DART spacecraft and the Italian Space Agency’s LICIACube prior to impact at the binary asteroid system. 

Illustration: Steve Gribben/NASA/Johns Hopkins