Mars was not spared the blows

In its early days, our solar system was a chaotic place, a kind of gigantic pool table crammed with balls shot madly in any direction. Planetesimal bodies, aggregates of matter less than 2,000 km in diameter from which the planets arise, collided with the worlds in formation. Mars He was not spared the blows. And some of them could be very large.

Scientists from Southwest Research Institute (SwRI) in Texas (USA) have modelled, from martian meteorites found on Earth, the mix of materials associated with these impacts, revealing that the Red Planet may have formed on a longer time scale than previously thought, even over 20 million years instead of two or four million years. years.

Knowing how Mars formed is not easy for planetary scientists. Billions of years of history have erased evidence of early impact events. Fortunately, some of this evolution is recorded in Martian meteorites.

Of roughly 61,000 space rocks found on Earth, only 200 or so are thought to be of Martian origin, kicked out of the Red Planet by more recent collisions.

Bombardment on Mars

These meteorites exhibit large variations in iron-loving elements, such as tungsten and platinum, which have a moderate to high affinity for iron. These elements tend to migrate from a planet’s mantle toward its central iron core during formation.

The evidence for these elements in the Martian mantle is important because it indicates that Mars was bombarded by planetesimals sometime after the formation of its primary core ended. Studying the isotopes of particular elements produced in the mantle by radioactive decay processes helps scientists understand when planet formation was complete.

“We knew that Mars received elements like platinum and gold from the first big collisions”says Simone Marchi of SwRI, lead author of an article in “Science Advances” that describes these results.

“According to our model, the first collisions produce a heterogeneous Martian mantle, similar to a marble cake. These results suggest that the prevailing view of the formation of Mars may be biased by the limited number of meteorites available for study.”.

Due to the ratio of tungsten isotopes in Martian meteorites, it has been argued that Mars grew rapidly within about 2-4 million years after the Solar System began to form.

However, large early collisions could have upset tungsten’s isotopic balance, which could support a Mars formation timescale of up to 20 million years, as the new model shows.

big impacts

“Collisions by projectiles large enough to have their own cores and mantles could result in a heterogeneous mix of those materials in the early Martian mantle”says co-author Robin Canup, assistant vice president of SwRI’s Division of Space Science and Engineering.

“This may lead to different interpretations of the timing of Mars formation than those that assume all projectiles are small and homogeneous.”.

The Martian meteorites that landed on Earth likely originated from a few locations around the planet. The new research shows that the Martian mantle could have received varying additions of materials from projectiles, leading to varying concentrations of iron-loving elements.

The next generation of missions to Mars, including plans to return samples to Earth, will provide new information to better understand the variability of elements in Martian rocks and the early evolution of the Red Planet.

“To fully understand Mars, we need to understand the role that early energetic collisions played in its evolution and composition.”Marchi concludes.

Font: ABC

Reference article: https://www.abc.es/ciencia/abci-marte-tambien-hizo-golpes-y-dur-mucho-tiempo-202002122006_noticia.html