4.1 billion-year-old Martian meteorite holds clues to the red planet’s watery past - CNN

Scientists have identified one of the oldest Martian rocks ever found on Earth — and it’s revealing new clues about the red planet’s earliest history, including evidence that water altered its crust at least 4.1 billion years ago.

The rose-colored meteorite, known as Teghaza 001, has a unique chemical composition that sets it apart from previously studied samples from Mars, scientists say.

“This is a very rare, ancient Martian meteorite, and it gives us a chance to look at the early crust and mantle of Mars, at a time when life was just starting on Earth,” said Yang Liu, a planetary scientist at NASA’s Jet Propulsion Laboratory in Pasadena, California, and lead author of a study on the sample published October 29 in the journal Science.

This meteorite is believed to have formed from magma derived from the mantle — a planet’s inner layer of hot rock — which later became part of the outer crust. “The chemistry of this sample shows it comes from a Martian crustal area we have not sampled before,” Liu added.

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Teghaza 001 is named after a salt plain in the West African country of Mali, where meteorite hunters discovered it in 2022. The meteorite consists of eight fragments weighing 798.5 grams (1.76 pounds) in total, with the largest weighing 442 grams (0.97 pounds).

The impact of an asteroid or comet that struck Mars blasted Teghaza 001 out of the red planet’s relatively weak gravity and into space. The meteoroid then started orbiting the sun, potentially for several million years before being captured by Earth’s gravity and entering our planet’s atmosphere. It’s hard to determine when the impact on Mars originally occurred, or even when the meteorite landed on Earth, but the sample’s surface features reveal that it might have spent some time in the desert before its discovery, according to Liu.

“It is always nice to see a new visitor from Mars, and this one is ancient — one of the oldest from the planet, and older than any home-grown Earth rock,” said Matthew Genge, an associate professor of Earth and planetary science at Imperial College London, who was not involved with the study.

“That alone is fascinating,” Genge said in an email. “It gives a window into the earliest stages of Mars history, a time when water is expected to have been present on the planet.”

An initial analysis didn’t immediately reveal that the rock was particularly old, and Liu almost passed on studying it.

“When I was first offered it,” she said, “the sample was classified as a shergottite, the most abundant type of Martian meteorite we have on Earth.”

Liu had previously analyzed several shergottites, which make up almost 90% of the known Martian meteorite collection and are usually less than 600 million years old, but she ultimately agreed to investigate the sample.

She noticed Teghaza 001 contained zircon, a type of crystal that forms when molten rock cools. “Zircons are like a time capsule that allows us to precisely date the formation age of a rock,” she said.

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Dating of the crystals indicated an age of at least 4.1 billion years, which means the meteorite formed roughly within the first 400 million years of Mars’s existence. To confirm this estimate, the sample was also processed via a new aging method developed by study coauthor Hayward Melton, a doctoral student at the California Institute of Technology.

“This method uses a laser to vaporize very small regions of a sample, instead of dissolving larger pieces of it,” Melton said in an email. “Using laser means that we can measure samples like Teghaza 001 significantly faster than traditional techniques.”

The team used a small laser beam — about one-tenth the diameter of a human hair — to analyze the tiny grains and crystals inside of the samples. This new technique reduced the time required to date a sample from a month to a day, Melton added, and left more of the original material available for further studies.

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The meteorite is a basalt, similar to rocks that cover the floor of Earth’s oceans and erupt from volcanoes in places such as Iceland and Hawaii, according to Genge.