NASA’s DART asteroid impact mission has revealed new information about twin space rock targets, Didymos and Dimorphos. Scientists used images collected by NASA’s DART to study the asteroids’ geological features and physical properties.
The team, led by Olivier Barnouin from Johns Hopkins University Applied Physics Laboratory, studied the surface of Didymos, the larger asteroid, and found it was rough with large boulders at high elevations and smoother at low elevations. Dimorphos, the smaller moonlet companion, has rocks across its surface with a wider range of sizes and is mostly craterless but riven with cracks.
The team used crater counts to determine that Didymos is 12.5 million years old, while Dimorphos is around 0.3 million years old. They found that Dimorphos likely formed from material flung away from Didymos and then clumped together under gravity.
Researchers also studied the size of boulders on Dimorphos and found they formed at different times rather than all at once, implying that the rocks on the surface are inherited from Didymos. This supports the idea that moonlets in binary asteroid systems form from material shed by their larger partners.
Additionally, scientists found that boulders on Dimorphos are being fractured over 100,000 years due to thermal fatigue caused by changing temperatures. This is the first time rapid thermal fatigue has been seen on a rocky asteroid made up of silicate materials and nickel-iron.
The findings from these research teams provide a detailed picture of the Didymos system before the DART impact and can inform the upcoming Hera mission from the European Space Agency, set to launch in October 2023.
Source: https://www.space.com/dart-asteroid-mission-didymos-dimorphos-age-origins