The last complete image of asteroid moonlet Dimorphos, taken by the DRACO imager on NASA’s DART mission from ~7 miles from the asteroid and 2 seconds before impact. The image shows a patch of the asteroid that is 100 feet across. Credit: NASA/Johns Hopkins APL

Johns Hopkins Applied Physics Laboratory investigators studying ejecta from the Double Asteroid Redirection Test spacecraft collision with the asteroid moonlet Dimorphos in Septbember now have a better understanding of what the test achieved. DART team members provided a preliminary interpretation of their findings during the American Geophysical Union’s Fall Meeting on Dec. 15, in Chicago.

“Now we use the observations to study what these bodies are made of and how they were formed – as well as how to defend our planet should there ever be an asteroid headed our way,” said Tom Statler, the program scientist for DART at NASA headquarters in Washington, DC.

Scientists estimate DART’s impact displaced more than two million pounds of the dusty rock into space. The team is using that data, as well as new telescopic observation information on the composition of the moonlet and characteristics of the ejecta, to learn just how much DART’s initial collision moved the asteroid, and how much movement came from the recoil.

“Studying the ejecta … is a key way of gaining further insights into the nature of Dimorphos’s surface,” said Andy Rivkin, DART investigation team co-lead at APL.

The team has calculated that momentum transferred when DART hit Dimorphos was roughly 3.6 times greater than if the asteroid had simply absorbed the spacecraft and produced no ejecta at all, indicating that the ejecta contributed to moving the asteroid more than the spacecraft did.

“It is information we would need to develop an impactor mission to divert a threating asteroid,” said Andy Cheng, DART investigation team lead from APL. “Understanding how a spacecraft impact will change an asteroid’s momentum is key to designing a mitigation strategy for a planetary defense scenario.”