We knew that the Dart mission changed Dimorphos’ trajectory. What we did not know is that its form also changed

At the end of September 2022, the Dart mission (Double Asteroid Redirection Test) It made historyInterestingly, stamping against an asteroid. The milestone was not on the impact itself but on achieving with him slightly divert the trajectory of an asteroid, Dimorphos.

The expected and the unexpected. In the almost three years since then, we have been learning New details on the effects of Dart’s impact on Asteroid Dimorphos. Now we know, for example, that Dart not only managed to divert the orbital trajectory of the space rock; He also achieved with his impact to make the asteroid orbit deform significantly

What happened. The asteroid, explained the team, initially had an oblate form, that is, flattened in the poles, such as the earth, “the shape of a hamburger.” After the impact, Dimorphos became a rather prolata, elongated in the poles, like a rugby ball.

“For the most part, our predictions pre-impact on how Dart would change the way Didymos and her moon (Dimorphos) move in space were correct,” ” explained in a press release Derek Richardson, who led the analysis of the effects of the probe. “But there are some unexpected discoveries that help provide a better image on how asteroids and other small bodies are formed and evolved over time.”

Tumbos. According to the team that analyzed these orbital changes, the impact would have made dimorphs pass from a state of equilibrium with its main asteroid Didymos similar to that of our moon with the earth, to an irregular one. That is, dimorphs always gave the same face to Didymos, at least Until Dart arrived.

Now the system is out of its alignment, Richardson pointed out. This implies that it can stagger changing orientation, even ending up “tumbos”, rotating chaotically and unpredictable.

Asteroid formation. Thanks to studies such as the one conducted by Richardson and the team, we can access new clues about the formation of asteroids. As explained by the team, the impact released small rocks that remained in the orbit of the asteroid system. These contributed to altering the orbital movement in the system, but these changes in the gravitational balance do not seem to have altered the form of didymos.

This implies, the team added, that the main asteroid of the system was rigid and firm enough to maintain its form after the formation of its moon dimorphs. The details of the work were Published in an article In the magazine Planetary Science Journal.

Hera’s turn. The scientific community now has new eyes on the Didymos system, those of Herathe mission of the European Space Agency (ESA) aimed at monitoring the system and collect new data In situ. If everything continues as planned, Hera will begin in October a trip that will lead her to reach the double asteroid towards the end of 2026.

The data compiled by Hera They will allow an even more exhaustive analysis of the impact of the Dart mission. This in turn will be what gives us key clues that allow us to plan missions that protect our planet from the asteroid shock.

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Image | NASA/JOHNS HOPKINS APL/STEVE GRIBBEN

*An earlier version of this article was published in September 2024