Scientists have found that the "Trojan" astroids in the orbit of Mars are significantly different from their counterparts and could appear as a result of the collision of the Red Planet with a large celestial body in the distant past.
Due to the fact that there is practically no atmosphere on Mars, the planet's surface is constantly being "bombarded" by asteroids and meteorites. The new study, published in Nature Astronomy, only highlights the impact small cosmic bodies have on the Red Planet's landscape.
Scientists analyzed a group of Trojan asteroids on Mars located at a stable point between the planet and the sun - the so-called fifth Lagrange point, or L5. While the Trojan astroids of other planets seem to be random space bodies captured by the planet's gravity, the Martian Trojans are something special. Their group was named the Eureka Cluster, after the largest asteroid in the cluster.
According to spectral analysis, asteroids in the Eureka Cluster are likely composed of olivine, a compound of magnesium and iron. The high content of olivine brings Eureka into a special A-type of rare asteroids, of which only 17 have been discovered to date. Most of the other asteroids in the vicinity of Mars are more "classical" asteroids with a high iron content.
The most interesting thing is that olivine is found in abundance on Mars. The chances that this is a mere coincidence and that rare stones were simply pulled by the planet from the depths of space are extremely low. On the other hand, the lead author of the study, David Polishchuk, a specialist at the Weizmann Institute of Science, notes that the Trojans were most likely formed as a result of a strong impact of a celestial body on the surface of Mars, as a result of which part of its mantle flew into orbit.
Polishchuk and his team developed a theory explaining how a number of asteroids could have entered a stable orbit and rotated in it for over a billion years. According to the results of the study, an asteroid with a diameter of 100-200 km crashed into the surface of Mars between 1 and 4.5 billion years ago. The team is trying to narrow the search for the crater left over from the impact, but so far the list of candidates is very extensive: there is both the huge North Polar Basin and the Hellas plain in the south.
“The biggest challenges facing this model are the timing at which Mars took its current orbit, and whether the formation of Trojan asteroids coincides with the appearance of Mars' two moons, Phobos and Deimos,” explains Nandine Barlow, expert on Mars history from Northern Arizona University, who was not involved in the study. In addition, she notes that the details of the impact itself - its angle, direction, asteroid speed - need to be studied in more detail and thoroughly.
In response, Polishchuk said that Phobos and Deimos may have nothing to do with the Trojans, since their orbit is unstable. Astronomers believe that in a few million years Phobos will reach the point at which it will simply be torn apart into a ring of asteroids, which for some time will revolve around the Red Planet, and then completely fall on it.
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Be that as it may, scientists need time and a much larger number of computer models that simulate the appearance of multiple craters on the surface of Mars. Only then will scientists be able to at least partially explain both the appearance of asteroids and the appearance of two moons. This work will also shed light on other Trojan asteroid clusters that scientists have long discovered in the solar system. Earth, Venus, and even some moons and dwarf planets have them. Perhaps, in fact, the asteroid "bombardment" at one time had a much greater impact on the formation of our star system than we think now.
Vasily Makarov