How did Mars get its gasses? A special space rock holds clues.

How did Mars get its gasses? A special space rock holds clues. thumbnail

A unique meteorite from Mars shows a surprising chemistry that could help scientists understand how terrestrial planets form. This is according to a new study on the old space rock.

Chemical clues from this far-flung sample suggest that Mars and Earth, often viewed as twins due to their shared rocky worlds and solar system neighbors, were formed in very different ways. Mars formed slowly and Mars formed much faster.

Current hypotheses regarding the creation of a rock planet like Mars or Earth suggest that elements in the planet’s interior should have similar chemical characteristics to those in its atmosphere. This is because the magma ocean covered the rocky planets in the early days our solar system, 4.5 billion years ago. The process of cooling the planets and solidifying their molten mantles probably resulted in the release of gasses that eventually became atmospheres.

These gasses were not just chemicals. These gasses were volatiles, chemical elements, and compounds that can vaporize quickly. Volatiles include carbon, oxygen, nitrogen, and hydrogen. Noble gasses are inert elements that don’t react with the environment. These chemicals allowed the development and support of life on Earth.

To look for signs of this process on Mars, Sandrine peron ,, a postdoctoral fellow at ETH Zurich’s Institute of Geochemistry and Petrology, compared two sources of the noble gas krypton from Mars. One source was a meteorite, which originated in the Martian interior. NASA’s Curiosity Rover sampled krypton isotopes from Mars’ atmosphere. The krypton signatures didn’t match, which was unexpected. This could change the sequence of events that led to Mars’ volatiles and atmosphere.

” This is kind of the reverse of the standard model for volatile accretion,” Peron states. Peron’s results are published in a paper in Science. “Our study shows that it is a bit more complicated .”

The debris from the birth of our sun formed the planets in our solar system. The swirling disk of dust and gas, known as a solar nebula around the new star, was formed when clumps of material coalesced. Some clumps, created by gravity and collisions, grew big enough to become planets or develop complex geological processes. Others remained inactive and small as comets and asteroids primitive.

[Related: Mysterious bright spots fuel debate over whether Mars holds liquid water]

Scientists believe that volatiles were introduced to the new worlds from the solar nebula during the early stages of planetary development. Later, as the solar nubula dissipated more volatiles were released from bombardments by chondritic meteorites. These small pieces of stony asteroids, which remain unchanged from the early days of the solar systems, delivered more volatiles. These meteorites were then melted into the magma seas.

If the atmosphere were created by space rock, planetary scientists would expect that the volatiles in a planet’s atmosphere would match those found in chondritic meteorites and not the solar nebula. Peron discovered that the Martian atmosphere is almost entirely solar-rich, but the krypton in the Martian interior was nearly purely chondritic.

Peron suggests that Mars may have been bombarded with chondritic meteorites in the early stages of its formation and then solidified as there was enough solar nebula left to form an atmosphere around it. She explains that the nebula would have dissipated around 10 million years after the sun formed, so the accretion of Mars would have had to be completed well before then, perhaps in the first 4 million years.

How did Mars get its gasses? A special space rock holds clues.
A sample of the Chassigny meteorite that revealed the Martian interior contains chondritic volatiles. Courtesy of Sandrine Peron

“It looks like Mars acquired its atmosphere from the primordial gas that permeated the solar system as it was forming,” says Matt Clement, a postdoctoral fellow studying terrestrial planet formation at the Carnegie Institution for Science who was not involved in the study. This generally fits with our picture. We believe Mars formed .”

much faster than the Earth.

Scientists often turn to Mars to study the formation of the early solar system because of its speed. Mars is only a tenth the size of Earth. It is also much less geologically active than Earth. This means that the Red Planet may still have many of the conditions of our planetary neighbors’ earliest days.

To study the chemistry on Mars, scientists must either send Curiosity Rovers to the planet to examine the material or examine fragments of Mars that have been thrown into space and landed on Earth. Only a few hundred of these meteorites exist.

Peron’s study of meteorites is unique. In 1815, it plummeted through Earth’s atmosphere, fracturing into pieces over Chassigny, France. Scientists have been studying the fragments of Chassigny meteorite and determined that it was likely to be from Mars’ interior. This is unlike all other Mars meteorites.

This study shows how much we still have to learn about planet formation, Clement states. He says that we still don’t know where the volatiles from our own planets or the closest planets came from. “The more we look into the formation of planets, the more complicated it seems .”

Each new distinction between Earth, Mars and other planets suggests even more diversity elsewhere, Clement says. “If it’s that easy to form planets that are that different so close to each other,” he says, what weird worlds might scientists find orbiting other stars?

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