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Rocky planets, such as Earth and Mars, are enclosed in a solid layer called crust that forms in the early stages of their evolution.
In a study published in the journal Nature a team of scientists led by researchers from the Center for Stellar and Global Training (CSPF) at the Natural History Museum of Denmark, showed that the Mars crust was formed 4,547 million years ago, much earlier than expected; This means that many processes involved in the formation of Mars as we know it – such as the formation of its core and the solidification of its magma ocean – have been completed in less than 20 years. million years after the formation of the solar system, the scientists said. Previous models suggest that these processes may have taken up to 100 million years
The new findings could have an important implication as to whether Mars has already sustained life. "Our results indicate that Mars has solidified and cooled in 20 million years." Martin Bizzarro, an author of the CSPF study, told Newsweek . [19659002] "This means that liquid water could have existed on the surface of the planet at that time and, therefore, this environment may have been kind for life to develop. This is much earlier than Earth about 100 million years ago, which means that life may be native to Mars – note that this is speculative and requires additional evidence. "
Scientists analyzed extracts from a Sahara Desert meteorite in 2011. This space rock, which is believed to come from the Mars crust, contains a mineral called zircon, which acts as a sort of time capsule
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The team was able to date the rotting uranium, which was trapped in zircon in the form of melted magma hardened in the early stages of the formation of the red planet.This technique allowed researchers to accurately determine the age of the crust in which the zircon was formed.
"We discovered the oldest minerals – zircons – from Mars," said Bizzarro. "These zircons, which are about 100 million years older than the oldest terrestrial zircons, tell us that Mars has evolved much earlier than the Earth. "
The new findings also have implications for our understanding of the shape of the planet. Currently, there are two main models to explain this:
The first model proposes that planets be formed in stages on a time scale of 50 to 100 million years, beginning as small dust particles, then merging into larger fragments. or hundreds of kilometers in diameter – known as planetesimals – before finally regrouping into a planetary embryo and finally, an entire planet.
The second model is more recent and suggests that training occurs much more rapidly in a process called "pebble accretion". In this scenario, the planets grow by the accretion of pebbles the size of a centimeter rather than a planetesimaux the size of one kilometer.
"These results indicate that the moment of formation of the primary crust is the final product of planetary formation." This makes it possible to support new planetary formation models where planets of the size of Mars and of the Earth develop by accretion of pebbles. Once the planet is formed by this process, it differentiates and crystallizes rapidly to form a crust. Previous models suggested that planetary differentiation could take up to 100 million years, "he said.
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