February 29, 2024

from SpaceWeather Website

Observations and simulations of

the DART strike on Dimorphos.

This is not what NASA expected to happen.

Back in Sept. 2022, the space agency's DART spacecraft slammed into asteroid-moon Dimorphos, blasting huge streamers of debris into space and changing its orbit around Didymos.

Mission planners figured there must be a crater where the spacecraft struck, but new research published this week in Nature Astronomy suggests something completely different happened.

"Our simulations indicate that the DART impact caused a global deformation and resurfacing of Dimorphos," the authors write.

 

"ESA's upcoming Hera mission may find a reshaped asteroid rather than a well-defined crater."

Led by Sabina Raducan, a postdoc at the University of Bern's Physics Institute in Switzerland, the team of researchers modeled DART's impact using Bern's hydrodynamics shock physics code.

The software has successfully reproduced other impacts such as the time in 2019 when Japan dropped a copper impactor into asteroid Ryugu.

After running more than 250 simulations, the team concluded that Didymos is a rubble pile, a loose mixture of dust, stones, and boulders,

"with a cohesive strength less than a few pascals."

DART's impact ejected more than 10 million kg of this material. Instead of producing a crater, DART changed the shape of the entire pile.

 

Computer simulations of

the global reshaping of Dimorphos.

"Our findings serve as crucial evidence regarding the origin of Dimorphos as a secondary in a double asteroid system," the authors say.

Their results suggest that Dimorphos is a loose collection of debris from the rapidly-spinning parent Didymos.

Whenever something flies off Didymos, because of, say, a meteorite collision, it tends to settle on Dimorphos, a process which can take several days to years.

Hera's visit to Dimorphos in 2027-28 may confirm these findings.

If so, it will give NASA something to think about as the space agency tries to figure out how to deflect potentially dangerous asteroids in the years ahead.

For more information, read the original research here.