How similar are Earth and Mars? Researchers have made an unprecedented discovery on the Red Planet: “Something special was there”

A series of rocks scattered along an ancient shoreline on Mars show that the Red Planet may have been much more Earth-like than scientists thought, according to a study published in the journal JGR Planets, Live Science reports Tuesday.

The rocks, discovered by NASA’s autonomous rover Curiosity, are unusually rich in manganese oxide – a chemical compound that adds to the growing list of evidence that Mars was once a planet that could and was willing to host life. of oxygen levels in the atmosphere similar to those on Earth, according to some scientists.

NASA believes that manganese “is an unsung hero in the evolution of life” on Earth

NASA believes that manganese “is an unsung hero in the evolution of life” on Earth. Scientists know from Earth’s geological history that manganese was abundant in rocks and oceans before the first life forms appeared, about four billion years ago, and that it paved the way for oxygen, the basis of life on earth. Earth.

The only known ways to obtain manganese oxide, however, involve either the abundant presence of oxygen or microbial life. But there is no very clear evidence regarding the first way and no evidence regarding the second, conditions in which scientists wonder how manganese oxide could have formed in the rocks discovered on Mars.

The formation of manganese oxide-rich rocks “is very easy on Earth because of the abundance of microbes and oxygen – which in turn has origins in microbial life – so all the indications point to life,” study coordinator Patrick Gasda told Live Science. , researcher at Los Alamos National Laboratory in New Mexico: “Of course we have no evidence of life on Mars, so if we’re trying to get oxygen in a completely abiotic (no life) system, our current understanding of Mars doesn’t provide no explanation”.

The Curiosity rover discovered these heavily weathered rocks while traveling through Gale Crater, an ancient bed of a suspected lake (154 kilometers in diameter), a place the rover has been exploring since 2012. The rover’s ChemCam instrument detected the presence of manganese oxide inside the rocks after vaporizing small fragments of them with the help of a laser and analyzing the resulting plasma cloud. According to this analysis, manganese oxide represents almost half of the chemical composition of these rocks.

At the location where Curiosity discovered these rocks, the rover’s instruments recorded a level change of 10 to 15 meters. Although it’s a small difference in level compared to the hundreds of meters the rover climbed during its mission, its presence indicates that “something special happened in that place,” Gasda told Live Science. The texture of the rocks seems to indicate where a river flowed into a lake.

“This means we are on or near the shore of the lake. However, it is one of the best hypotheses at our disposal”, according to Gasda, who specified, however, that this interpretation of his is not very certain due to insufficient data.

If this hypothesis is correct, these rocks could have been brought to the area by the waters of the river flowing into the lake, similar to the manganese oxide-rich rocks found on the shores of shallow lakes on Earth.

These rocks represent “new evidence for the existence of liquid water in Mars’ past”

These rocks represent “new evidence for the existence of liquid water in the past of Mars, which is beneficial for life,” said Manasvi Lingam, an astrobiologist at the Florida Institute of Technology, who was not involved in this research: “This study provides new evidence in support of the hypothesis that Mars could have hosted life”.

However, not all scientists agree that these rocks could represent evidence of a past rich in oxygen on Mars. According to Jeffrey Catalano, a professor of environmental and planetary sciences at Washington University in St. Louis, who was not involved in the study, the presence of oxidized rocks may help scientists understand whether Mars, like Earth, went through a “fragmented transition” from a time when oxygen was rare, at a time when it was much more common.

“However, the impact of manganese oxides on how we understand such a transition has been overestimated both here and in previous studies,” he told Live Science.

Jeffrey Catalano participated in a 2022 study that concluded that manganese oxide can easily form under conditions similar to those on Mars, in the absence of atmospheric oxygen. This study, which is based on laboratory experiments, showed that elements such as chlorine and bromine, which were abundant in Mars’ past, can transform manganese dissolved in water into manganese oxide minerals. This discovery offered an alternative to oxygen that could explain the existence of rocks like those newly found on Mars.

“There are some forms of life even on Earth that don’t need oxygen to survive,” said Kaushik Mitra, a geochemist at the University of Texas at San Antonio who led the 2022 study. it means that there could not have been life in the past on Mars, “only that there probably weren’t life forms that needed oxygen.”

Publisher: BC