Asteroid Dimorphos, which was the subject of an unprecedented experiment aimed at diverting its trajectory, currently looks like a pile of debris from the larger asteroid Didymos around which it orbits, according to a study coordinated by a researcher born in Romania , informs AFP.
Dimorphos would be made up of a heteroclite silicon-based assembly. Photo: NASA (Archive)
Dimorphos was struck in September 2022 by the DART probe launched by NASA to test the ability of the American space agency to divert from its trajectory an asteroid that would risk colliding with Earth, writes Agerpres.
The success of this mission, which was carried out about 11 million kilometers from Earth, could only be measured by the impact on the orbit of the asteroid Dimorphos around Didymos.
In this dual system, the first celestial body measures about 160 meters in diameter, initially making a complete rotation around the second celestial body, with a diameter of 800 meters, in almost 12 hours. This time was shortened by over half an hour after impact. The detail was also captured in images by an Indian microsatellite that accompanied the DART mission and was monitored from Earth with the help of telescopes.
According to an international team, coordinated by Sabina Răducan, a researcher specialized in small celestial bodies at the University of the Swiss city of Bern, these data “suggests that Dimorphos is a pile of scraps“, summarized the study published in the journal Nature Astronomy.
“According to the simulations, the only solutions I found assume that Dimorphos was originally a very fragile 'being' that put up very little resistance” at the impact with the DART probe and its 650 kilograms, explained to AFP a co-author of the study, Patrick Michel, astrophysicist at the Côte d'Azur Observatory.
Its fragility was so great that the impact, “instead of forming only a crater with a diameter of about 10 meters, it would have actually led to a deformation of the entire body” of the celestial object, added Patrick Michel, one of the team leaders on the DART mission.
Gravel field
The use of conditional mode is required until the European Space Agency's (ESA) HERA probe, which will arrive near Dimorphos in 2026, can examine the asteroid with much larger resources.
Dimorphos would be composed of a silicon-based heteroclite assembly, but not of the “the sand of Saint-Tropez, but rather a gravel field like La Promenade des Anglais in Nice, with rocks everywhere“, added Patrick Michel. The rocks are quite small, as less than 40% of them are over 2.5 meters high, according to simulations supported by the last images taken by the DART probe before it crashed onto the asteroid's surface.
Its structure, which a high-frequency radar of the HERA probe will examine, would be characterized by great porosity, a detail that explains the asteroid's fragility.
These aspects militate in favor of the theory of the birth and growth of Dimorphos based on the debris ejected by his “older brother” Didymos, which spins on its own axis like a puppet and has a somewhat similar shape. Didymos spins fast enough to to eject by centrifugal effect a part of its matter, which agglomerated to form Dimorphos.
This would be “the good news”believes Patrick Michel, confirming that a silicate asteroid like Dimorphos has roughly the same behavior as the more common asteroids, which are made of carbonates, like Bennu and Ryugu, meaning “shows very little resistance”.
“A natural laboratory”
Researchers will then know what we are dealing with, if in the distant future humans will have to deflect an asteroid to save Earth. The new study represents a major breakthrough, as these celestial objects “they have behavior that defies our intuition, because of their environment which is very different from that on Earth”emphasized the same expert.
In 2029, the asteroid Apophis will fly past Earth at a distance of 32,000 kilometers, giving researchers “a natural laboratory” to study these celestial objects.
A science mission is in the pipeline to study the behavior of Apophis during its flyby without the need for a probe to touch the asteroid, as it will be visible from Earth.
Sabina Răducan graduated from the “Mihai Viteazul” National College in Bucharest in 2012, according to her Facebook account. She then studied at the Faculty of Astronomy, Space Sciences and Astrophysics at the University of Kent in the United Kingdom and obtained a doctorate at Imperial College University from London in 2020. She worked for the NGO Center for Complex Studies, and since August 2020 she is a researcher at the University of Bern.
