Asteroids

This is the Last Thing DART saw as it Smashed Into its Asteroid Target

The first-ever planetary defense technology demonstration mission successfully conducted its mission, slamming into the surface of a distant asteroid and going out in a blaze of glory. NASA’s Double Asteroid Redirection Test (DART) spacecraft acted as a kinetic impactor, colliding with the small and harmless asteroid Dimorphos on September 26 at 7:14PM ET, with the hope of deflecting it.

“DART’s success provides a significant addition to the essential toolbox we must have to protect Earth from a devastating impact by an asteroid,” said Lindley Johnson, NASA’s Planetary Defense Officer. “This demonstrates we are no longer powerless to prevent this type of natural disaster. Coupled with enhanced capabilities to accelerate finding the remaining hazardous asteroid population by our next Planetary Defense mission, the Near-Earth Object (NEO) Surveyor, a DART successor could provide what we need to save the day.”

The last minutes of the spacecraft’s mission can be seen in this video:

Dimorphos is a small asteroid moonlet, just 530 feet (160 meters) in diameter. It orbits a larger, 2,560-foot (780-meter) asteroid called Didymos. Neither asteroid poses a threat to Earth, and the impact should change the way Dimorphos orbits Didymos, making the duo the perfect target for this test. NASA says that DART’s impact demonstrates a viable mitigation technique for protecting the planet from an Earth-bound asteroid or comet, if one were discovered.

DART launched on November 24, 2021, and after 10 months of flying about 7 million miles (11 million kilometers through space, caught up with Dimorphos. DART weighed 1,260-pounds (570-kilograms) and crashed into the asteroid at roughly 14,000 miles (22,530 kilometers) per hour, which is expected to have slightly slowed the asteroid’s orbital speed.

A graphic showing all the objects necessary in DART’s planetary defense test. Credit: NASA, APL.

Our lead image shows what DART’s camera saw 2 seconds and 12 km away before impact, showing the asteroid to be a rubble pile, with enormous boulders. Astronomer Will Gater put a human figure next to the intended crash site for reference of the size of the boulders on Dimorphos.

There was actually one more image that the spacecraft’s sole instrument captured. DRACO, (Didymos Reconnaissance and Asteroid Camera for Optical navigation, was in the process of sending back the image data to Earth when the transmission was rudely interrupted by the impact:

DART’s final look at the asteroid moonlet Dimorphos before impact. The spacecraft’s on board DRACO imager took this final image ~4 miles (~6 kilometers) from the asteroid and only 1 second before impact. DART’s impact occurred during transmission of the image to Earth, resulting in a partial picture. The image shows a patch of the asteroid that is 51 feet 16 meters) across. Dimorphos’ north is toward the top of the image. Credits: NASA/Johns Hopkins APL

Overnight and today in the morning after, images from ground-based telescopes have been coming in, confirming that DART made impact. Researchers will be able to measure precisely show much the impact changed Dimorphos’ orbit, but they expect the impact to have shortened its orbit by about 1%, or roughly 10 minutes. Being able to precisely measuring how much the asteroid was deflected is one of the primary purposes of the full-scale test.

View from Les Makes Observatory in Le Reunion

Additionally, space telescopes like the James Webb Space Telescope were also monitoring the impact. Here’s the initial data from JWST:

Before impact, the DART spacecraft released a smaller satellite, the Italian-built LICIACube. This tiny spacecraft followed DART on its way to its doom, taking pictures of the immediate aftermath. Those images were just released this morning in a press conference from the Italian team:

“Planetary Defense is a globally unifying effort that affects everyone living on Earth,” said Thomas Zurbuchen, associate administrator for the Science Mission Directorate at NASA Headquarters in Washington. “Now we know we can aim a spacecraft with the precision needed to impact even a small body in space. Just a small change in its speed is all we need to make a significant difference in the path an asteroid travels.”

More details about DART’s test will be coming out in the next few weeks as researchers study the data coming in from all the telescopes around the world, so stay tuned. You can keep track of any news here on Universe Today, as well as on NASA’s Planetary Defense website.

In the meantime, know that Bruce Willis and the dinosaurs would be proud.

Nancy Atkinson

Nancy has been with Universe Today since 2004, and has published over 6,000 articles on space exploration, astronomy, science and technology. She is the author of two books: "Eight Years to the Moon: the History of the Apollo Missions," (2019) which shares the stories of 60 engineers and scientists who worked behind the scenes to make landing on the Moon possible; and "Incredible Stories from Space: A Behind-the-Scenes Look at the Missions Changing Our View of the Cosmos" (2016) tells the stories of those who work on NASA's robotic missions to explore the Solar System and beyond. Follow Nancy on Twitter at https://twitter.com/Nancy_A and and Instagram at and https://www.instagram.com/nancyatkinson_ut/

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