Asteroids that bombarded Mars about 4.5 billion years ago may have carried enough water to form a global ocean 300 meters deep. Scientists base this conclusion on the analysis of 31 meteorites from Mars discovered on Earth. The tempting results may point to a hidden reservoir of water that still exists on the Red Planet today. On the other hand, the study may have implications for understanding both the early history of the Red Planet and the history of Earth itself.

“The observation that water-rich asteroids bombarded Mars means they may have contributed to Earth as well, but that’s hard to quantify,” says cosmochemist Martin Bizzarro of the University of Copenhagen in Denmark and co-author of the new study. research, reports Space.com. “Unlike Mars, Earth has plate tectonics and the earliest records of our planet’s history have been erased.”

The researchers then turned to Mars, and some rocks hurled from Mars by giant impacts crashed into the Earth. These meteorites serve as bits of Mars on Earth for scientists to study, and they carry the record of water history on the Red Planet in the form of isotopes—slightly different flavors of an element, each containing a different number of neutrons in the molecule. . core.

Scientists led by Ke Zhu of the University of Paris and the University of Bristol in Great Britain measured the relative abundances of chromium-54 and chromium-53 in meteorites and found that the high chromium-54 ratio was close to that of chromium-54. . a type of asteroid called carbonaceous chondrite. In particular, isotopic analysis shows a subset of carbonaceous chondrites associated with the Renazzo meteorite that fell in 1824. Scientists believe this meteorite came from a population of water-rich bodies that formed outside of our solar system’s giant planets. These asteroids can contain up to 10% water by mass.

Not all Martian water was formed by the impact of carbonaceous chondrites during the first 100 million years of the Solar System’s history. A lot of water has also reached the surface of Mars as a result of gas released from the molten mantle of the Red Planet. How much water was ejected remains a mystery, but with outgassing and impacts, enough water may have entered the Martian surface to form a global ocean up to 1.5km deep.

Scientists debate where Mars and Earth get their water. Research on rocks brought from the Moon by the Apollo missions contain traces of water, suggesting that Earth contained at least some water at the time of the giant impact that formed the Moon.

As on Mars, water on Earth could have evaporated and then refilled as a result of collisions. Scientists have suggested many potential multipliers with studies focused on comets or asteroids. Interestingly, the water in carbonaceous chondrites is similar to water in Earth’s oceans in terms of the deuterium to hydrogen ratio (D/H) (deuterium is a heavy isotope of hydrogen with an additional neutron). However, it is difficult to prove that most of the water on Earth originated here, because our planet has destroyed most of its old crust.