Image credit: Johns Hopkins APL/Olivier Barnouin
Examining data collected during NASA’s Double Asteroid Redirection Test (DART) mission, which sent a spacecraft in 2022 to intentional collision with the asteroid moon Dimorphos, the mission’s science team discovered new information about the origin of the target binary asteroid system and why the DART spacecraft was so effective at shifting Dimorphos’ orbit.
In five recently published papers in the journal Nature Communications, the team explored the geology of the double asteroid system which includes the lunar asteroid Dimorphos and the parent asteroid Didymos, to characterize its origin and evolution and constrain its physical characteristics.
“These discoveries give us new insights into how asteroids can change over time,” said Thomas Statler, principal scientist in the Small Solar System Division at NASA Headquarters in Washington. “This is important not only for understanding the near-Earth objects that are central to the planet’s defense, but also for our ability to read the history of our solar system from these remnants of planet formation. This is just part of the wealth of new knowledge we have gained from DART.”
Olivier Barnouin and Ronald-Louis Balluz of the Johns Hopkins Applied Physics Laboratory (APL) in Laurel, Maryland, led the paper, which analyzed the geology of both asteroids and drew conclusions about their surface materials and internal properties. In images taken by DART and the accompanying LICIACube cubesat provided by the Italian Space Agency (ASI), the team observed the topography of the smaller asteroid Dimorphos, which featured boulders of varying sizes. In comparison, the larger asteroid Didymos was smoother at low altitudes, though rocky at higher altitudes, with more craters than Dimorphos. The authors concluded that Dimorphos probably separated from Didymos in a major mass event.
There are natural processes that can speed up the rotation of small asteroids, and there is growing evidence that these processes may be responsible for changing the shape of these bodies or even forcing material from their surface.
The analysis showed that both Didymos and Dimorphos have faint surface features, leading the team to suggest that Didymos has a surface age 40 to 130 times older than Dimorphos, with the former estimated at 12.5 million years and the latter less than 300,000 years The low surface strength of Dimorphos probably contributed to the significant effect of DART into its orbit .
“The images and data collected by DART in the Didymos system provided a unique opportunity for a close-up geological survey of the near-Earth asteroid binary system,” Barnouen said. “From these images alone, we were able to gain a lot of information about the geophysical properties of Didymos and Dimorphos and expand our understanding of the formation of these two asteroids. We also have a better understanding of why DART was so effective in moving Dimorphos.”
Maurizio Paiola of the National Institute of Astrophysics (INAF) in Rome and co-authors led the paper, which compared the shapes and sizes of different boulders and their distribution on the surface of the two asteroids. They identified physical characteristics of Dimorphos that indicate it formed in stages, likely from material inherited from its parent asteroid Didymos. This finding supports the prevailing theory that some binary asteroid systems arise from the remnants of a larger parent asteroid accreting into a new asteroid moon.
Alice Lucketti, also of INAF, and her colleagues found that thermal fatigue—the gradual weakening and cracking of material caused by heat—can rapidly destroy boulders on the surface of Dimorphos, creating surface lines and changing the physical characteristics of this type of asteroid. faster than previously thought. The DART mission was probably the first observation of this phenomenon on this type of asteroid.
Led by researcher Naomi Murdoch of ISAE-SUPAERO in Toulouse, France, and her fellow researchers Jeanne Bigot and Pauline Lombardo, Didymos found that Didymos’ bearing capacity—the surface’s ability to withstand applied loads—is at least 1,000 times lower than this. dry sand on Earth or lunar soil. This is considered an important parameter for understanding and predicting surface response, including for asteroid displacement purposes.
Colas Robin, also of ISAE-SUPAERO, and co-authors analyzed the surface boulders on Dimorphos, comparing them to rocks on other asteroids with debris piles, including Itokawa , Ryugu and to benn . The researchers found that the boulders have similar characteristics, suggesting that all these types of asteroids formed and evolved in a similar way. The team also noted that the elongated nature of the boulders around the DART impact site means they likely formed as a result of impact processing.
These latest discoveries form a more robust view of the Didymos system’s origins and add to the understanding of how such planetary bodies formed. As ESA’s (European Space Agency) Hera mission prepares to revisit the DART impact site in 2026 to further analyze the effects of the first-ever planetary defense test, this study provides a series of tests for what Hera will find and contributes to current and future research. missions, while strengthening the potential of planetary defense.
Johns Hopkins APL managed the DART mission for NASA’s Planetary Defense Coordination Office as a project of the agency’s Planetary Mission Program Office. NASA provided mission support from several centers, including the Jet Propulsion Laboratory in Southern California, Goddard Space Flight Center in Greenbelt, Maryland, Johnson Space Center in Houston, Glenn Research Center in Cleveland, and Langley Research Center in Hampton, Virginia.
For more information on the DART mission:
https://science.nasa.gov/planetary-defense-dart
