NASA is winding up to punch an asteroid

Asteroids striking Earth have been the subject of many potential apocalyptic scenarios—for which humans have never tested contingency plans, until now. 

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This week, NASA will launch the Double Asteroid Redirection Test (DART), an unprecedented attempt to knock an asteroid slightly off its course. The golf cart-size spacecraft will travel over 6 million miles and collide with an asteroid moonlet—a small asteroid that orbits another asteroid—named Dimorphos in fall 2022. Although the targeted asteroid does not pose any threat to Earth, NASA says the agency is interested to see whether “intentionally crashing a spacecraft into an asteroid is an effective way to change its course, should an Earth-threatening asteroid be discovered in the future.” 

The mission will launch no earlier than 1:20 a.m. Eastern Time on Wednesday, November 24, from the Vandenberg Space Force Base in California.

“A lot of times when I tell people that NASA is actually doing this mission, they kind of don’t believe it at first,” Nancy Chabot, a planetary scientist at the Johns Hopkins University Applied Physics Laboratory, told NPR. “Maybe because it has been the thing of movies.”

The DART spacecraft will hit Dimorphos at a speed of nearly 15,000 miles per hour, but not with the cinematic goal of blowing it up. Instead, NASA hopes that the force of the impact will change the asteroid’s course by a fraction of a percent—a less glamorous result, but one that will create small but measurable differences in the asteroid’s orbit.

Three years after the impact, the European Space Agency’s Hera mission will conduct a follow-up investigation, measuring Dimorphos’s physical properties in detail to tease out DART’s long-term effects on its orbit.

“DART is a first step in testing methods for hazardous asteroid deflection,” Andrea Riley, DART Program Executive at NASA Headquarters, said in a 2020 statement discussing the mission. International collaboration on a mission such as this is key, she said, especially because “potentially hazardous asteroids are a global concern.”  

Dimorphos poses absolutely no risk to Earth. NASA’s Earth Impact Monitoring system catalogues potential future Earth impact events for the next 100 years. The Sentry program scans the list of known asteroids and continuously updates impact probabilities. Astronomers have located at least 90 percent of the largest asteroids in our region of space, and none of those pose any risk of impact within the next century. 

Dimorphos is a smaller asteroid, only about 500 feet in diameter, and those are not so thoroughly catalogued. Astronomers have only found about 40 percent of space rocks under 460 feet wide. None of the those discovered so far has any significant chance to hit Earth. But, if a rock of that size did, it could take out a large city. 

[Related: Yes, a killer asteroid could hit Earth]

“Although there isn’t a currently known asteroid that’s on an impact course with the Earth,” Lindley Johnson, NASA’s planetary defense officer, told NPR, “we do know that there is a large population of near-Earth asteroids out there.”

To watch the launch of the DART mission, check out launch coverage on NASA Television, NASA’s YouTube channel, the NASA app, and agency social media channels starting at 12:30 a.m. Eastern Time Wednesday. You can also bookmark this page to view the launch—it will be live here, too.