DART spacecraft strikes asteroid target at 14,000mph

The culmination of 10 months flying in space, and part of NASA’s overall Planetary Defense strategy, DART demonstrated the viability of protecting our planet from an Earth-bound asteroid or comet, should one be discovered.

Mission control at the Johns Hopkins Applied Physics Laboratory (APL) in Laurel, Maryland, announced the successful impact yesterday at 1914 EDT. 

“At its core, DART represents an unprecedented success for planetary defence, but it is also a mission of unity with a real benefit for all humanity,” NASA Administrator Bill Nelson said in a statement. “As NASA studies the cosmos and our home planet, we’re also working to protect that home, and this international collaboration turned science fiction into science fact, demonstrating one way to protect Earth.”

DART targeted the asteroid moonlet Dimorphos, a small body 160m in diameter that orbits a larger, 780m asteroid called Didymos. Neither asteroid poses a threat to Earth, NASA said.

The investigation team will now observe Dimorphos using ground-based telescopes to confirm that DART’s impact altered the asteroid’s orbit around Didymos, which is one of the primary purposes of the full-scale test. Researchers expect the impact to shorten Dimorphos’ orbit by about one per cent, or roughly 10 minutes.

“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.”

The spacecraft’s sole instrument, the Didymos Reconnaissance and Asteroid Camera for Optical navigation (DRACO), plus a guidance, navigation and control system that works with Small-body Maneuvering Autonomous Real Time Navigation (SMART Nav) algorithms, enabled DART to identify and distinguish between the two asteroids.

These systems guided the 570kg box-shaped spacecraft through the final 56,000 miles of space into Dimorphos, intentionally crashing into it at roughly 14,000mph to slightly slow the asteroid’s orbital speed. DRACO’s final images, obtained by the spacecraft seconds before impact, revealed the surface of Dimorphos in detail.

Fifteen days before impact, DART’s CubeSat companion Light Italian CubeSat for Imaging of Asteroids (LICIACube), provided by the Italian Space Agency, deployed from the spacecraft to capture images of DART’s impact and of the asteroid’s resulting cloud of ejected matter. In tandem with the images returned by DRACO, LICIACube’s images are intended to provide a view of the collision’s effects to help researchers better characterise the effectiveness of kinetic impact in deflecting an asteroid.

“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.”

Roughly four years from now, the European Space Agency’s Hera project will conduct detailed surveys of Dimorphos and Didymos, with a particular focus on the crater left by DART’s collision and a precise measurement of Dimorphos’ mass.