Mars was fully formed—crust and all—within just 20m years after the solar system began

Maybe we’re the aftermath of an advanced civilization sending their last hope of avoiding extinction to the closest planet to mars they found habitable…

TL;DR

New research reveals that Mars developed its crust within just 20 million years of the solar system’s formation, significantly faster than Earth. By studying zircon crystals in Martian meteorites, scientists found that Mars had its initial crust by 4.547 billion years ago. This rapid development, compared to Earth’s 100-million-year delay, suggests that Mars had an early advantage in becoming habitable. The findings imply that Mars’ atmosphere was likely thin, allowing the planet to cool swiftly. Earth’s slower cooling, due to a massive impact that re-melted it, reset its planetary development timeline.

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Mars developed into a complete planet, including its crust, within just 20 million years of the solar system’s formation. This swift development suggests that the Red Planet may have gained a 100-million-year advantage over Earth in terms of habitability, according to new research.

Geochemical studies of zircon crystals found in Martian meteorites indicate that Mars formed its initial crust by about 4.547 billion years ago, scientists reported on June 27 in Nature. This is just 20 million years after the sun’s surrounding gas disk gave rise to the solar system’s planets.

A planet’s outermost layer, or crust, represents the final phase in the development of terrestrial planets like Mars, Earth, Venus, and Mercury. This process begins with particles accumulating from the protoplanetary gas disk, which eventually form molten material that creates a hot magma ocean. As the magma ocean cools and crystallizes, it develops a dense metallic core, followed by an outer crust. Simulations suggest this entire process typically takes between 30 million to 100 million years.

However, analyses of Martian zircons, led by planetary scientist Laura Bouvier of the University of Copenhagen, indicate that Mars’ crust formed much faster. The team examined isotopes in seven zircon crystals. Isotopes are variants of an element with the same number of protons but different numbers of neutrons, giving them different masses. Some isotopes are unstable and decay into other elements at known rates. By measuring the decay of uranium-235 to lead-207 and uranium-238 to lead-206, Bouvier and her team found that the zircons are up to 4.476 billion years old.

The researchers then used another isotopic decay system, lutetium-176 to hafnium-176, and discovered that Mars’ earliest crust is even older. Zircons crystallizing from such rocks should have initially contained more hafnium than what the analyses showed. Based on the hafnium content and lutetium-hafnium decay rates, the team estimated that the original magma crust solidified around 4.547 billion years ago.

Subsequently, the crust was partially melted by heavy asteroid bombardment, although the impacts didn’t completely revert it to a magma ocean, the researchers propose. The zircons containing remnants of this earlier crust formed when, around 4.476 billion years ago, Mars cooled and solidified again.

“Having Mars cool so quickly puts limits on how massive its atmosphere could have been,” says Linda Elkins-Tanton, a planetary scientist at Arizona State University in Tempe who wrote a commentary accompanying the study. By considering how quickly a planet cools and how fast the sun can strip away its atmosphere, scientists can infer how much water and carbon dioxide might have been released by the magma ocean to create an early atmosphere. But in Mars’ case, Elkins-Tanton says, that atmosphere would have been quite thin to allow for such rapid heat loss.

Mars would also have solidified roughly 100 million years before Earth, giving the Red Planet a head start on becoming habitable. Earth, on the other hand, was almost certainly entirely molten at that time, likely due to a massive impact that formed the moon and re-melted the whole planet (SN: 4/15/17, p. 18), Elkins-Tanton notes. “That restarted everything on Earth.”