Scientists have discovered that the asteroid targeted in NASA's Double Asteroid Redirection Test (DART) may have been reshaped by the impact. A new investigation into the impact aftermath has revealed that the asteroid, the smaller component of the binary asteroid system, exhibits a loose “rubble pile” structure.
DART collided with the moon Demorphos, which orbits the larger space rock Didymos, on September 26, 2023. The goal of this cosmic attack was to see if a kinetic impact could change the path of an asteroid around a larger body and to verify that this method could be used to shift a rock. spacecraft one day if it falls on a collision course with Earth.
Six months after the impact, NASA confirmed that the mission was a success, reducing the time it took Dimorphos to orbit the larger companion asteroid by 33 minutes. After the collision, one of Dimorphos' orbits around Didymos takes about 11 hours and 23 minutes. Now, new research shows that the impact may also have had major impacts on the environment appearance From dimorphos.
Related: Scientists hail DART's success 6 months after the historic asteroid crash
A team led by scientist Sabina Raducan of the University of Bern used state-of-the-art computer models to determine that Dimorphos is a loose asteroid and a pile of rubble. This also means that the Moon may have formed from material ejected from its larger partner, the asteroid Didymos.
The simulations that were closest to the impact observations suggest that Dimorphos is poorly consolidated and lacks large rocks on its surface.
“Before DART arrived at Dimorphos, we didn't know what to expect. Since the system is so far from Earth, Dimorphos was not resolved properly. So, we could have encountered anything from a homogeneous object — basically a large boulder the size of a rock,” Radukan told the website. Space.com: “From dimorphos – to a loose rubble pile or something in between.” “So, while the outcome of the impact came as a surprise to most people, it was one of the expected scenarios.”
Raducan added that while the preparedness meant that the Dimorphos-accumulating nature of the debris wasn't too surprising, DART revealed other things that surprised the team.
“Dimorphos has a very different composition from the asteroids Ryugu and Bennu, but their reaction to the impacts, which look very similar, was surprising,” Raducan said. “For all of these asteroids, cratering occurs in a low-gravity, low-cohesion regime, where the crater grows several times larger than the ejecta.
Additionally, according to the team's calculations, rather than simply creating an impact crater, the DART impact appears to have completely reshaped dimorphos. This would have happened through a process called global deformation. In contrast, the reshaping appears to have caused the Moon's exterior to resurface with material from its interior.
The team's simulations showed that between 0.5% and 1% of Dimorphos' mass was ejected by the DART impact, while 8% of its mass was redistributed, significantly reshaping and reshaping the asteroid. Raducan added that these results indicate that the structural integrity and responses to impacts of small asteroids are likely to be strongly influenced by their internal compositions and the distribution of their constituent materials.
The team's findings could help scientists better understand the Dimorphos and Didymos asteroid system as well as dissect the dynamics of other binary asteroids in the solar system.
“The physical properties and structure of Dimorphos as extracted in this study indicate that the young moon was likely formed by the fall and reaccretion of rotational mass from Didymos,” Raducan said. “These results provide clues about the prevalence and properties of similar binary systems in our solar system, contributing to our broader understanding of the history of their formation and evolution.”
DART's primary goal was to test planetary defense methods, and Raducan said the mission has certainly achieved results in that regard. She explained that these results will benefit the process of developing future asteroid exploration missions and will have an impact on strategies to mitigate asteroid collisions, and guide the design of future planetary defense initiatives.
“The implication for planetary defense is that small asteroids with a pile of rubble, such as Dimorphos, are very effective at deflection, and the kinetic impact technique would be a suitable deflection mechanism,” Raducan said. “However, before attempting a deflection, a reconnaissance mission will likely be necessary to accurately assess the asteroid's properties.”
The researchers now plan to compare the simulation results with data collected by the European Space Agency's (ESA) upcoming Dimorphos mission, to validate and improve their models.
“The results of the Hera mission will be useful in validating our models and turning the kinetic impactor into a reliable mechanism for asteroid deflection,” Raducan concluded. “We also plan to expand our analysis to include a wider range of asteroid types and/or shapes, such as Dinkenish, as recently imaged by the Lucy mission.
“These studies will strengthen the power of our planetary defense predictions and contribute to a more comprehensive understanding of asteroid mechanics and composition.”
The team's research was published Monday (February 26) in the journal Nature Astronomy.
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