When an asteroid attack a planet, it can deliver a powerful punch — as the dinosaurs discovered damaged them 66 million years ago. But what if two asteroids hit at the same time and in the same location?
A first study of its kind published in a magazine Icarus investigate this phenomenon on Mars. Looking at the planet, researchers have discovered hundreds of craters that are likely the result of the effects of a binary system where one asteroid orbits another, like moon orbiting the Earth.
“They are really hard to find,” said Dmitrii Vavilov at the University of Côte d’Azur in France, lead author of the study. But the findings suggest these double holes are there, he said.
The first detection of a binary asteroid was made by NASA’s Galileo spacecraft while it sailed to Jupiter in 1993. While taking pictures of an asteroid called Ida in flight, the Scientists on the mission were shocked to discover a second asteroid orbiting nearby. “They were very confused,” said Harrison Agrusa, an astronomer at the University of Maryland who was not involved in the new study. “People are debating what’s wrong with the camera.”
It’s not. Instead, Ida is the first confirmation that asteroids can rotate in pairs, and in some cases even more. Ida’s companion, later named Dactyl, is extremely small, but proof of their existence. “It caused a huge shockwave in the community,” Agrusa said.
Based on observations of millions of other asteroids in the solar system, scientists today estimate that 1 in 6 asteroids – about 16% – is 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—A goal of NASA and the European Space Agency (ESA) Asteroid protection mission later this year.
Asteroids frequently strike planets and moons, so it is expected that binary asteroids will too. However, finding double craters can be difficult, especially among the multitude of other craters on places like our moon. On Earth, it’s even harder, 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 Målingen. “We dated these structures very precisely and found that they formed at the same degree,” said Jens Ormö from the Center for Biology in Spain, who led the analysis of the craters. age”. published in 2014. Another pair of promising candidates are known to be 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 orbiters, Vavilov and his colleagues examined nearly 32,000 craters larger than 4 kilometers across. to look for pairs of craters.
Their results show that 150 pairs appear to be the result of binary impacts, totaling 300 individual craters. These estimates come from finding pairs of crater shapes expected after a binary asteroid collision. These include teardrop craters, where two craters overlap; peanut craters, where they are connected at their edges; and double craters, where there is a gap between the two craters. The orientation of the two craters depends on the position of the two asteroids at the time of impact.
