Martian meteorites analyzed by scientists suggest that the Red Planet may not have had an ocean of global magma, unlike Earth. The same study indicates that Mars received water from at least two very different sources early in its history.
A team of scientists, led by Jessica Barnes, a professor of planetary science at the University of Arizona's Lunar and Planetary Laboratory in the United States, chemically analyzed the Black Beauty meteorite and the Allan Hills 84001, very controversial in the 1990s for allegedly containing Martian microbes.
Barnes and his team managed to reconstruct the history of water from Mars by looking for two types of clues: hydrogen isotopes (or light hydrogen) or deuterium (heavy hydrogen). The relationship between these two isotopes gives scientists clues about the processes and possible origins of water in rocks and minerals, where they are found. The results of the investigation were published in Nature Geoscience.
The team began investigating the hydrogen isotopic composition of the Martian crust, specifically studying samples originating from the crust – the meteorites Beleza Negra and Allan Hills.
The isotopic proportions of the meteorite samples were between the proportion found in the Earth's water and the proportion found in the Martian atmosphere. In addition, the proportion was similar to the younger rocks analyzed by the Curiosity rover.
These results indicate that the chemical composition of this water has been consistent for about 3.9 billion years – a completely unexpected result, writes ScienceAlert.
"Martian meteorites spread everywhere, so trying to find out what these samples are really telling us about water in the mantle of Mars has historically been a challenge," explained Barnes.
When the team compared the results to previous research on hydrogen isotopes in Martian mantle meteorites, they discovered something truly surprising: the mantle meteorites fit into two distinct groups of igneous rock called shergotite.
These two distinct chemical signatures indicate two different water reservoirs in the Martian mantle, which may indicate that, unlike Earth, a global ocean of liquid magma below the mantle has not homogenized the upper layer.