NASA’s DART asteroid collision mission a smashing success!
Two weeks after a NASA spacecraft purposely collided with an asteroid, the agency confirmed the impact changed its orbit much greater than initially expected.
On Sept. 26, 2022, the Double Asteroid Redirection Test, or DART, slammed into asteroid Dimorphos, a moonlet of the larger asteroid Didymos, at a speed of 4 miles (6 kilometers) per second. NASA hoped the refrigerator-sized spacecraft would change the small asteroid’s orbit by about 10 minutes from the initial period of 11 hours, 55 minutes.
After two weeks of analysis, it turns out the orbital period was reduced to 32 minutes to 11 hours, 23 minutes, plus or minus 2 minutes — three times more than the agency had hoped.
This was the first time humanity attempted to change the motion of a celestial object, according to NASA, and the first test of a planetary defense technique called kinetic impact. It’s important to note, however, that this particular asteroid does not pose a risk to Earth before or after the DART impact.
“All of us have a responsibility to protect our home planet. After all, it’s the only one we have,” said NASA Administrator Bill Nelson in an Oct. 11 agency news release. “This mission shows that NASA is trying to be ready for whatever the universe throws at us. NASA has proven we are serious as a defender of the planet. This is a watershed moment for planetary defense and all of humanity, demonstrating commitment from NASA’s exceptional team and partners from around the world.”
Didymos is about 530 feet (160 meters) across while its parent asteroid is about 2,560 feet (780 meters) across. The DART spacecraft had a mass of about 570 kilograms.
NASA said it defined mission success before the impact as changing the orbital period of Didymos by about 73 seconds but said up to 10 minutes was likely.
The agency said one possibility for the 30-minute period change could be the ejecta that was thrown away from the asteroid as a result of the impact. Further analysis of the ejecta is needed, and many tons of rock were thought to be displaced and launched into space by the collision, according to NASA.
Indeed, images after the impact showed debris tails spreading away from the asteroid body by as much as 6,000 miles (10,000 kilometers). NASA said more information about the asteroid’s properties will be required to better understand the effects of ejecta recoil.
“DART has given us some fascinating data about both asteroid properties and the effectiveness of a kinetic impactor as a planetary defense technology,” said Nancy Chabot, the DART coordination lead from the Johns Hopkins Applied Physics Laboratory in Laurel, Maryland. “The DART team is continuing to work on this rich dataset to fully understand this first planetary defense test of asteroid deflection.”
A follow up mission by the European Space Agency called Hera is expected to launch in 2024 and rendezvous with the binary asteroid system by 2026 to perform a post-impact survey of Dimorphos.
Videos courtesy of NASA
Derek Richardson has a degree in mass media, with an emphasis in contemporary journalism, from Washburn University in Topeka, Kansas. While at Washburn, he was the managing editor of the student run newspaper, the Washburn Review. He also has a website about human spaceflight called Orbital Velocity.