[ad_1]
This image montage made by NASA's Curiosity rover shows the surface of the Mars planet, which researchers believe hardened only 20 million years after the birth of the Sun, much earlier than expected
The crust that surrounds the rocky planets and makes possible the emergence of life took shape on Mars earlier than expected and at least 100 million years earlier than on Earth, researchers said Wednesday.
By badyzing the grains of mineral zircon extracted from a Martian meteorite known as Black Beauty, they determined that the outer layer of the red planet hardened 4.547 billion years ago. only 20 million years after the birth of the Sun.
"The primary formation of the Mars crust – which is the final product of the planet's formation – has occurred much faster than previously thought," said Martin Bizzarro, researcher at the Center. for Star and Planet Formation. Nature.
"Our results indicate that Mars could have had an environment with oceans, and potentially life, much earlier than Earth," he told AFP.
Water is considered an essential precursor of life, at least as we know it.
Mars was once much more similar to the Earth, with a thick atmosphere, abundant water and global oceans.
Until now, mathematical models have suggested that the solidification of the red planet has taken up to 100 million years.
The new study addresses the issue by examining a piece of Mars that streaked in the Sahara Desert and was discovered in 2011.
The Black Beauty meteorite weighed 320 grams (11 ounces) when it was found. The researchers got 44 grams of precious stone from the space and crushed five to extract seven pieces of zircon that could be used in experiments.
"Like a time capsule"
By measuring the decay of lead from uranium that had been trapped in zircon as the melting magma of the young Mars was hardened, scientists were able to date precisely the crust of which zircon was found to be present. ;is formed.
"I'm glad we chose this strategy," Bizzarro said. "Zircon is like a time capsule."
There are two main models for the formation of planets.
In one, it occurs in stages, with small dust particles that coagulate into "planetesimals" – rock fragments 10 to 100 kilometers in diameter – that collide to form planetary and planetary embryos on a period of 50 to 100 million years.
According to a more recent model, planetary growth proceeds faster and is fueled by what is called "pebble accretion", the stratified accumulation of particles measured in centimeters and meters that are weakly related to gases.
"Our data supports more recent models indicating the very fast formation of terrestrial planets," said the authors.
The new timeline suggests that something similar may have happened on our planet, but only after the Earth was "reset" by the giant impact that formed the Moon about 4.4 billion years ago. 39 years, said Bizzarro.
Mars is believed to have a dense metal core with a radius of about 1800 kilometers (1100 miles), consisting mainly of iron, nickel, and sulfur.
The core is surrounded by a largely dormant mantle – about 1,500 km thick – composed mainly of silicon, oxygen, iron and magnesium.
Finally, the average crust is about 50 km deep, with a maximum of about 125 km. The earth's crust reaches on average 40 km, but accounts for one third of the thickness of the Martian crust once the size of the planet is taken into account.
Explore further:
Rare metals on Mars and Earth imply colossal impacts
More information:
Laura C. Bouvier et al. Evidence of the extremely rapid crystallization of the ocean of magma and the formation of crust on Mars, Nature (2018). DOI: 10.1038 / s41586-018-0222-z
Source link
