NASA’s DART Mission Hits Asteroid

On Monday night, NASA demonstrated that humans may have a defense against asteroids hitting Earth.

NASA’s Double Asteroid Redirection Test, or DART, is the agency’s first attempt to move an asteroid in space. It successfully hit asteroid moonlet Dimorphos—a 530-foot diameter asteroid, or just about as tall as the Washington Monument, that orbits larger asteroid Didymos—a little after 7 p.m.

The 1,260-pound DART spacecraft was launched in November 2021 and hit Dimorphos—which does not pose a threat to Earth—at approximately 14,000mph while seven million miles away from Earth. NASA performed the test hit to see how it affects the motion of the asteroid in space. After successfully hitting the asteroid, the DART mission demonstrates that in theory if an asteroid was projected to hit Earth, the asteroid may be able to be moved before it becomes a major threat. 

“DART’s success provides a significant addition to the essential toolbox we must have to protect Earth from a devastating impact by an asteroid,” Lindley Johnson, NASA’s planetary defense officer said. “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.”

DART is “the world’s first planetary defense technology demonstration.” According to NASA, planetary defense is “applied planetary science to address the NEO impact hazard.” These NEOs are objects like asteroids or comets that orbit the Sun, but their orbits can bring them too close to Earth, or within 30 million miles of Earth’s orbit. 

“Planetary defense is a globally unifying effort that affects everyone living on Earth,” Thomas Zurbuchen, associate administrator for the Science Mission Directorate at NASA, said. “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.”

NASA scientists must examine the data to determine how much Dimorphos’ momentum was changed by the hit. Additionally, a global team is using dozens of telescopes stationed around the world and in space to observe the asteroid system. Specifically, they will examine the ejecta produced and measure Dimorphos’ “orbital change to determine how effectively DART deflected the asteroid.” This information will be used to help assess future planetary defense scenarios and improve computer modeling used to predict the effectiveness of this technique as a way of deflecting asteroids. However, it will take some time to truly determine if DART’s mission successfully deflected Dimorphos. 

The spacecraft’s sole instrument, the Didymos Reconnaissance and Asteroid Camera for Optical navigation in conjunction with a sophisticated guidance, navigation and control system working with Small-body Maneuvering Autonomous Real Time Navigation algorithms allowed DART to identify and target the smaller asteroid. Specifically, SMART Nav collected and processed images from DRACO’s high-resolution camera and used algorithms to determine the maneuvers that needed to be made in the last four hours before the collision. 

“I’m excited about DART’s historic success today,” House Space and Aeronautics Subcommittee Chair Don Beyer, D-Va., said. “This mission represents the forward-thinking of NASA and its partners on a key capability for our planetary defense. While the likelihood of an asteroid impact to Earth is low, the potential damage of an impact could be devastating. DART’s successful test gives us a demonstrated technique for how we might nudge off course a potentially hazardous asteroid headed for Earth.”

NASA provided images of the asteroid prior to impact. Additionally, the agency also had a live broadcast of the impact. 

Johns Hopkins Applied Physics Laboratory manages the DART mission as a project for NASA.

DART represents one of many measures that NASA is taking for planetary defense and other innovative technology. For example, the agency’s NEO Surveyor is a new infrared space telescope that is designed to find hazardous asteroids in the solar system; it is set to launch by 2026.