Scientists have analyzed the isotopic composition of meteorite samples that contain natural materials from the Martian crust – Northwest Africa 7034 and ALF 84001.
Starting with the NASA Mariner 9 Martian mission in the 1970s and to this day, scientists have received a lot of evidence that there could once be ponds on the Red Planet — lakes, rivers, and even oceans. However, how they originated, what they were and why today Mars is a large desert – astronomers continue to speculate and express their assumptions on these topics. No exception was the new work of planetologists from the USA and Great Britain, which was published in the journal Nature Geosience.
“Many scientists have tried to figure out the history of the origin of water on Mars. How long has it been in the crust of Mars? Where did the water in the rocks of this planet come from? What can water tell us about how Mars was formed and evolved? All of these questions remain unanswered, ”said study head Jessica Barnes of the University of Arizona.
The basis of the work was samples of ancient Martian meteorites Northwest Africa 7034 and ALF 84001, or rather, their isotopic ratios. As a result of their analysis, it turned out that the Red Planet could receive water supplies from at least two different protoplanetary bodies and at different times – according to scientists, about 3.9 and 1.5 billion years ago.
As it turned out, the fractions of hydrogen isotopes in these two meteorites were identical. After studying the mineral composition of celestial bodies, the researchers found that it includes two types of volcanic rocks – enriched and depleted Shergottites (rich in magnesium and iron, contain various sizes of crystals and minerals).
The authors explain that the first type of rock is more likely to resemble celestial bodies from the far edges of our system containing a lot of deuterium (one of two stable isotopes of hydrogen, the core of which consists of a proton and a neutron). The second type of minerals by the ratio of the fractions of hydrogen isotopes in the water stored in them was more similar to terrestrial rocks. In addition, data previously obtained from the Curiosity apparatus, which launched to the Red Planet in 2011, showed that the isotopic ratio of protium (the lightest hydrogen isotope) and deuterium in meteorites was constant for four billion years.
Thus, planetologists summarize, we can conclude that the crust of the Red Planet and its mantle were formed not from one source of rocks: presumably, two celestial bodies collided with each other or with the progenitor of Mars at the dawn of the life of the solar system. Water on the Red Planet, respectively, appeared also from different sources – at least two.
“In the past, we believed that the depths of Mars were very homogeneous and similar in composition to the Earth. Therefore, all differences in the fractions of isotopes in meteorites were attributed either to pollution during measurements, or to the accumulation of molecules from the Earth’s atmosphere, after the meteorite fell on its surface. The presence of two sources of water at once, hidden in the bowels of Mars, says a lot about what objects were in the inner part of the Solar system and participated in the formation of its planets. This discovery is also important in order to understand whether life could exist on Mars, ”adds Barnes.