NASA’S DART mission was a success. Here’s how to watch it.


NASA’S DART mission was a success. Here’s how to watch it.

Update: NASA’s DART spacecraft successfully smashed into the asteroid Dimorphos on Monday night, in the space agency’s first planetary-defense test. NASA livestreamed the spacecraft’s journey, down to the moment it crashed into the asteroid’s surface at roughly 14,000 miles per hour.

Scientists are still crunching the numbers to find out how much the crash affected Dimorphos’ orbit – a process that will likely continue for some time. In addition to the information beamed to Earth from DART, telescopes around the world were trained on Dimorphos to gather even more data on the historic collision.

As Science Reporter Dan Vergano reported for Grid last week, NASA’s Double Asteroid Redirection Test (DART) spacecraft is planned to collide with the asteroid Dimorphos, some 6.8 million miles from Earth, this evening.

It’s all part of a $325 million NASA mission. The 1,325-pound DART spacecraft will hit the asteroid while traveling at more than 14,000 miles per hour to test whether intentionally sending a spacecraft to ram into an asteroid could potentiallydeflect it and help protect us from one approaching Earth in the future.


How to watch tonight

The DART spacecraft is slated to hit the Dimorphos asteroid at 7:14 Eastern time tonight. You can watch starting at 6 p.m. on NASA TV or at

The data: Is an asteroid likely to approach Earth?

“Fewer than 1,000 ‘potentially hazardous asteroids’ a kilometer (0.62 miles) or wider — big enough to have continental or planetary consequence on impact — orbit near Earth, and none are on a trajectory for our planet,” Vergano writes in his latest report. “Instead, unknown mid-sized ones, about the size of Dimorphos, are the real concern.

“An asteroid like Dimorphos hitting the Earth on a typical 1-in-12,000-year trajectory would leave a crater a mile wide and 1,150 feet deep, according to this fun and scary impact simulator from Purdue University and Imperial College London.”

This is the type of asteroid with the potential to be a “city-buster” – not large enough to put the entire planet at risk, but still sizable enough to devastate any area where it strikes.

Only in the last decade have scientists really taken seriously the risks from “airbursts” of larger meteors that streak through the atmosphere for hundreds of miles before exploding, another potential target for deflections. A 2013 airburst over a Russian city smashed windows and blew apart with tremendous force, indirectly causing hundreds of injuries.


The numbers behind the collision

Science lens: What do scientists hope to learn from the mission?

The target asteroid Dimorphos is orbiting a larger asteroid called Didymos. By measuring whether and how much the collision changes Dimorphos’ orbit, astronomers can assess the effectiveness of the DART experiment. NASA expects the impact to change the orbital speed of Dimorphos by less than 1 percent. While that may not sound like a lot, small deflections could be enough to nudge future asteroids out of harm’s way.

And the DART results could improve scientists’ understanding of space rocks generally. The interior composition of asteroids, whether they are solid, or porous, or just loose agglomerations of rock is hard to tell without sampling them. DART’s impact should reveal just how solid are asteroids like Dimorphos, a common variety near Earth. This in turn tells us the best way to deflect them, whether by impacts or, alternately, by putting satellites into orbit around them to serve as “gravity tractors” that slowly alter their trajectory over time.

What can we learn from this mission?

Politics lens: Why is NASA cutting the budget for its next asteroid-hunting mission?

NASA in March slashed the $170 million planned budget for a new infrared space telescope, the Near-Earth Object (NEO) Surveyor, meant to find “city-buster”-sized asteroids flying near Earth.


Instead, NASA has prioritized other missions with a shorter time window for its launch to Mars or deeper into the solar system. While NEO Surveyor can be launched into a stable orbit near Earth any time, those other missions will face years-long waits for a second shot at a launch if they miss the window.

NASA’s Lindley Johnson told Grid that he felt comfortable with the delay in launching NEO Surveyor, given the low odds of a dangerous impact if the mission waited until 2028. Outside astronomers such as MIT’s Richard Binzel are less sanguine, saying that since we have the technology to detect incoming asteroids, we are obligated to watch out for them on the rare chance something undetected is already headed our way.

Asteroid detection is a mission that NASA only embraced in 2016 and it does not have a political constituency behind its missions like the International Space Station or NASA’s jumbo space rocket, which delivers jobs to states with NASA centers.

Congress appears ready to increase NASA’s budget to around $26 billion next year, making planetary defense a small portion of its portfolio. DART was a $325 million mission the size of a golf cart, and NEO Surveyor is an updated version of the WISE infrared space telescope that NASA launched a decade ago, optimized for asteroid detection. Ironically, that explains some of its trouble gaining traction: Because it is not a large mission, it lacks political support from large defense contractors.

Thanks to Dave Tepps for copy editing this article.