The differences found between Martian meteorites and rocks examined by NASA’s Spirit rover suggest thatMars had an oxygen-rich atmosphere 4 billion years agoThat is, long before oxygen appeared in the Earth’s atmosphere 2.5 billion years ago.
Scientists at the University of Oxford (UK) have investigated the composition of Martian meteorites found on Earth and data from NASA’s Spirit rover, which examined surface rocks in the Gusev crater on Mars. The fact thatrocks on the surface are five times richer in nickel than meteorites surprised them, causing them to question whether meteorites are typical volcanic products of the red planet.
“We have shown that meteorites and surface volcanic rocks are consistent with similar origins deep inside Mars, but thatrocks on the surface come from a more oxygen-rich environment, probably caused by the recycling of materials rich in this molecule in the interior “, affirms the professor Bernard Wood, of the Department of Sciences of the Earth and co-author of the study that has published this week the magazineNature.
“The finding is puzzling, since while the meteorites are geologically young, around 180 million years to 1.4 billion years old, the Spirit rover was analyzing a very old part of Mars, more than 3.7 billion years old.” Wood adds. While the geological makeup of Mars may vary greatly from region to region, the researchers believe that differences are more likely to arise through a process known assubduction, in which the material is recycled inside.
Wood and his team have concluded thatthe surface of Mars was oxidized very early in the planet’s history and that, through subduction, this oxygen-rich material was brought into the shallow interiorand was recycled back to the surface during eruptions 4 billion years ago. Meteorites, on the other hand, are the youngest volcanic rocks that emerged from deep within the planet, so they were less influenced by this process.
“The implication is thatMars had an oxygen-rich atmosphere in a time long before the appearance of atmospheric oxygen on our planet“The authors conclude. As oxidation is what gives Mars its distinctive color, it is likely that the red planet was humid, warm, and oxidized 4 billion years ago, that is, 1.5 billion years since the Earth’s atmosphere. Earth would be enriched with oxygen.
