See the strange physics of double-impact asteroids | MarketingwithAnoy

When an asteroid hitting a planet, it can give a powerful blow – as the dinosaurs discovered to their detriment 66 million years ago. But what if two asteroids hit at the same time and in the same place?

A first study of its kind published in the journal Icarus investigates this phenomenon on Mars. Looking at the planet, scientists have discovered hundreds of craters, most likely due to the effects of a binary system, where one asteroid orbits another, just as the moon orbits the Earth.

“They are really hard to find,” said Dmitrii Vavilov of the Côte d’Azur University in France, the study’s lead author. But the results show that these binary craters are there, he says.

The first discovery of a binary asteroid was made by NASA’s Galileo spacecraft when it traveled to Jupiter in 1993. While taking pictures of an asteroid called Ida on its way, missionary scientists were shocked to find another asteroid in orbit nearby. “They were so confused,” said Harrison Agrusa, an astronomer at the University of Maryland who was not involved in this new study. “People were discussing whether there was anything wrong with the camera.”

It was not. Instead, Ida was the first confirmation that asteroids could orbit in pairs, and in some cases even more. Ida’s companion, later named Dactyl, was incredibly small, yet a proof of their existence. “It triggered a big shock wave in the community,” Agrusa says.

Based on observations of the other millions of asteroids in the solar system, scientists today estimate that about 1 in every 6 asteroids – about 16 percent – are part of a binary system. We can see these orbits around the solar system, especially in the asteroid belt between Mars and Jupiter, with one of the most famous pairs – Didymos and its small companion, Dimorphos – the target of an asteroid defense from NASA and the European Space Agency (ESA). mission later this year.

Asteroids regularly hit planets and moons, so it would be expected that binary asteroids would too. However, it can be difficult to find binary craters, especially among the countless other craters in places like our moon. On Earth, it is even more difficult as geological processes quickly erase evidence of impacts.

The best candidate for a binary crater on Earth today is the Lockne crater in Sweden and a smaller crater nearby called the Measurement. “We dated these structures very accurately and saw that they were formed at the exact same age,” says Jens Ormö from the Astrobiology Center in Spain, who led the analysis of the craters. published in 2014. Another promising candidate pair is known, the Kamensk and Gusev craters, but their location – on the border between Russia and Ukraine – makes them difficult to study in the current global climate.

On Mars, craters can remain visible for billions of years. So using high-resolution images of the surface taken by Mars orbits, Vavilov and his colleagues examined nearly 32,000 craters larger than 4 kilometers across to hunt for craters.

Their results showed that 150 pairs appeared to be the result of binary influences, a total of 300 individual craters. These estimates come from looking for few crater shapes that would be expected after a binary asteroid collision. These include tear-drop craters, where the two craters overlap; peanut craters, where they are connected at their edges; and double craters where there is a gap between the two. The orientation of the two craters depends on the position of the two asteroids at the time of impact.

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