Meteorite Found in Sahara Is 'Rosetta Stone for Mars'

A pink-hued rock plucked from the Sahara in 2022 has turned out to be one of the oldest known pieces of Mars on our planet. NASA says the nearly two-pound meteorite, named Teghaza 001 after the salt plain in Mali where it was found, dates back at least 4.1 billion years, putting it among the three oldest of the 435 known meteorites from Mars, CBS News reports. "It was only after we started looking closely that we realized this meteorite is really unique," says Yang Liu, the lead author of a study published in Science on Thursday. "One of the paper's reviewers called it a Rosetta Stone for Mars," says Liu, a planetary scientist at NASA's Jet Propulsion Laboratory.

"Mars does not undergo global-scale plate tectonics, so its surface preserves geological records spanning more than four billion years of planetary evolution," researchers wrote. By comparing its chemistry and minerals to data from Mars missions, researchers confirmed its origin and found evidence the rock was reshaped by Martian water early in the planet's history. Liu calls it "a witness to a time when Mars was likely warmer and wetter than it has been for most of its history."

• In a news release, NASA said the uniqueness of Teghaza 001's mix of minerals sets it apart from other ancient Martian meteorites. "While invaluable, the others provide more limited glimpses of Mars' geological history. They include ALH84001, which is composed almost entirely of one mineral and is similar in age to Teghaza 001," NASA said. "The other meteorite, nicknamed 'Black Beauty,' formed about 2.1 billion years ago and is composed of small, volcanic rock fragments."
• It's unclear when Teghaza 001 arrived on our planet, reports Reuters. "It was blasted by an impact from the surface of Mars and was flying through space until its path crossed that of Earth. It then entered the atmosphere as a meteor and survived as a meteorite by landing in the Sahara," Liu says. "We do not know when the sample landed on Earth."

• NASA said it's impossible to determine exactly where Teghaza 001 came from, but its mix of volcanic minerals and zircon crystals matches terrain in several locations in Mars' southern highlands. Researchers say it will aid their understanding of how the Martian crust formed and how its early water cycle may have worked.
• One question the meteorite can't answer is whether there was life on Mars, though researchers say it adds to evidence that the right conditions for life existed. "The rock is a snapshot in time that shows how a wetter early Mars with a thick atmosphere could have supported habitable conditions but that these conditions were waning rapidly over the first billion years or so of Mars' existence, trending towards its currently dry and inhospitable environment," says study co-author Lee Saper, a planetary scientist at NASA's Ames Research Center.