[ad_1]
Mars was a fully formed planet – a crust and everything – inside only 20 million years from the birth of the solar system. This fast formation means that the red planet has probably jumped 100 million years on Earth in terms of habitability, according to a new study.
Geochemical badyzes of mineral zircon crystals extracted from Martian meteorites reveal that Mars had formed its first crust 4.547 billion years ago, scientists report on June 27. Nature. It's just 20 million years after the gas disk around the sun gave birth to the planets of the solar system.
The emergence of the outermost shell of a planet, or crust, is the last stage of the formation of telluric planets like Mars, Earth, Venus and Mercury. The process begins with the accretion of particles from the protoplanetary gas disk; finally, these particles form a molten material that constitutes an ocean of hot magma. As the ocean of magma cools and crystallises, it forms a dense metal core and then an outer crust. Simulations of the whole process suggest that this occurs on time scales of 30 million up to 100 million years.
Martian zircon badyzes, conducted by global scientist Laura Bouvier of the University of Copenhagen, suggest that the Mars crust is formed much faster, however. The team badyzed isotopes in seven of the crystals. Isotopes are forms of an element that have the same number of protons but a different number of neutrons, and therefore different mbades. Some isotopes are unstable and decay radioactively to other elements at known rates. Using the decay of uranium 235 in lead 207 and uranium 238 in lead 206, Bouvier and his team determined that zircons date back to 4,476 billion years ago.
The team then turned to another radioactive isotope disintegration system, Lutetium 176 to 176 hafnium, and discovered that the oldest crust of Mars is even older. The zircons crystallizing from these rocks should have contained much more hafnium than the researchers found in their badyzes. Based on the amount of hafnium present and the decay rates of lutetium and hafnium, the team calculated that the original magma crust should have solidified about 4.547 billion d & # 39; years.
Some time after that, heavy shelling by asteroids partially melted this crust, although the impacts did not completely return to an ocean of magma, suggest the researchers. Zircons containing traces of this anterior crust were born when, about 4,476 billion years ago, Mars cooled for good.
"The fact that Mars is cooling down so quickly limits the magnitude of its atmosphere," says Linda Elkins-Tanton, a global scientist from the Arizona State University in Tempe, who wrote a commentary accompanying the new study. Depending on how fast a planet is cooling down and how fast the sun can strip its atmosphere, researchers can estimate how much water and carbon dioxide could be released by the ocean magma to form an atmosphere. early. But in the case of Mars, this atmosphere would have been thin enough to allow such a rapid heat loss, says Elkins-Tanton.
Mars would also have solidified about 100 million years before Earth made it – giving the red planet a head start on livability. Our home planet was almost certainly completely melted at that time, perhaps thanks to a giant shot that formed the moon and reshaped the entire planet, says Elkins-Tanton. (SN: 15/04/17, p. 18"It all started up again on Earth."
[ad_2]
Source link
