Mars may have been covered in a 300-meter-deep ocean in the solar system's early days
Meteorites that smashed into Mars during the earliest days of the inner Solar System may have carried an ocean's worth of water to the planet.
Researchers from the University of Copenhagen in Denmark analyzed the concentration of a rare chromium isotope, known as chromium-54, in samples from meteorites that came to Earth from Mars, a New Scientist report reveals.
They estimated that early meteorite showers likely brought enough water to Mars to create a 300-meter-deep ocean.
Lead researcher Martin Bizzarro and a team of colleagues conducted their sample analyses to estimate how much water was deposited on the Red Planet. Mars' uppermost layer contains the chemical signatures of carbonaceous, or C-type, meteorites that bombarded the planet's crust as it solidified approximately 4.5 billion years ago.
Mars' upper layer isn't made up of large tectonic plates, as is the case on Earth, meaning the materials on its surface shouldn't be churned and regurgitated in the same way they have on our planet over millennia. As such, meteorite materials should be pretty well preserved on the red planet's surface. Meanwhile, the rocks from the mantle below should still show what Mars was like before meteorites bombarded it.
"It’s a bit like DNA," Bizzarro told New Scientists in an interview. "Carbonaceous-type asteroids have a very distinctchromium isotope composition relative to the inner solar system."
The scientists analyzed the chromium-54 in samples of meteorites that came from Mars' surface and mantle and ended up on Earth. By doing so, they could estimate the total mass of the meteorites that collided with Mars during its early period. They outlined their findings in a paper in Science Advances.
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The lower known limit for C-type meteorites is 10 percent water. The scientists said that if the meteorites that originally bombarded Mars met this lower limit, they would have brought enough water to create an ocean of 300 meters in depth over the whole planet.
"This means that two of the most important ingredients necessary to life – organic molecules and water – were present on Mars during a time before Earth's moon even formed, say the researchers," Bizarro told New Scientist.
Of course, the University of Copenhagen scientists are dealing in estimates and relying on analyses of ancient space rocks that determine their rough origin — scientists determine that these ancient rock samples came from ancient meteorites that originated on Mars via a complex process of elimination.
More research of the Martian surface in the coming years, aided in part by NASA's and the European Space Agency's Mars Sample Return mission of the 2030s, will allow the scientific community to gain a much better understanding of the red planet and put many of the models and estimates of recent months and years to the test.
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