Asteroid Demorphos is undergoing a unique experiment to divert its path, according to a study published Monday that makes the giant asteroid Didymos look like a pile of debris orbiting it.
A collision with the asteroid Demorphos was conducted in September 2022 by NASA's DART spacecraft to test its ability to deflect an asteroid that could hit Earth.
The success of this mission, which took place some 11 million kilometers from Earth, can only be measured by the impact of the Demorphos orbit around Didymos.
In this strange twin, the first star, which is approximately 160 meters in diameter, orbits the second star, which is 800 meters in diameter, in about 12 hours. Time was reduced by more than half an hour after the clash.
These details were captured in images by a small Italian satellite accompanying the DART mission, and followed by telescopes from Earth.
“Heap of Rubble”
According to an international team led by Sabina Radukan, an expert on small celestial objects at the University of Bern, the data “suggests that Dimorphos is a pile of debris,” according to their findings published in the journal “Nature Astronomy.” “
Patrick Michel, an astrophysicist at the French Côte d'Azur Observatory, co-author of the study, explained, “According to the simulations, the only solutions we found were that Dimorphos was a very fragile object at the beginning and did not show much resistance to the collision of the massive “Dart” spacecraft. 610 kilograms.
The co-head of the “DART” team said that this weakening was so great that “the impact, instead of creating a crater about ten meters in diameter, would lead to a complete disintegration of the asteroid's body.”
These results are pending the European Space Agency's HERA probe, which is due to arrive at Dimorphos in 2026 and is planned to study the asteroid with more precise methods.
It is believed that Dimorphos may have a heterogeneous composition based on silica (silicon dioxide), but “not from a sand field in Saint-Tropez, but more like a gravel field like the one on the Promenade des Anglais in Nice. ) with rocks everywhere,” said Patrick Michel. .
These rocks are very small, as less than 40% of them are larger than 2.5 meters, according to simulations of recent images taken by the DART spacecraft before the crash.
After all, the structure of the asteroid, which can be probed by the Hera probe's low-frequency radar, is probably very porous, which explains its fragility.
“Brother”
This supports the hypothesis of the birth and development of a space body based on debris ejected by “big brother” Didymus, which rotates itself like a toy bulbul (spinning top), which is somewhat similar. This happens so quickly that it expels part of its material by centrifugal effect, which aggregates and forms dimorphoses.
This is “good news” for Patrick Michael, as he confirms that a silica-rich asteroid like Dimorphos has the same behavior as “i.e., very low resistance” typical carbon asteroids like Bennu or Ryugu.
Therefore, we already know what to expect, and it is necessary to deflect an asteroid to save it from the danger of hitting Earth in the distant future. The expert affirms that this is a major achievement because these objects “have behavior that challenges our intuition because their environment is completely different from Earth's environment.”
In 2029, according to Michael, the asteroid Apophis will pass close to Earth at a distance of about 32,000 kilometers, providing a “natural observatory” for studying these stars.
A mission is currently being prepared to study the behavior of Apophis without the need to touch it as it is visible from Earth.
