H. G. Wells sent his Martians to Earth in metal cylinders that unscrewed in a sandpit near Woking. The real thing turns out to be rather less dramatic, and rather more pink. Teghaza 001, a reddish rock picked up in the Sahara in Mali in 2022, has been identified as a piece of Mars at least 4.1 billion years old, making it one of only three Martian meteorites known from the planet’s early history, and perhaps the oldest of the roughly 435 that have reached us.
The study, led by planetary scientist Yang Liu of NASA’s Jet Propulsion Laboratory and published in Science, was reported by Reuters and CBS News at the end of October. The meteorite was found in eight pieces, the largest about the size of a fist, roughly 34 kilometres from the Malian village of Bir Chali, and takes its name from the salt plain where it turned up. It is a gabbro, a coarse volcanic rock of feldspar and pyroxene, with uranium-bearing zircon crystals that let Caltech geochemist Francis Tissot help date a fragment smaller than a fingernail. Its mix of minerals matches what NASA’s Mars Reconnaissance Orbiter has seen in the southern highlands, possibly near the Hellas Basin. “It was blasted by an impact from the surface of Mars and was flying through space until its path crossed that of Earth,” said Liu, who admits that “we do not know when the sample landed on Earth.”
The exciting part is the water. Liu says “multiple lines of evidence in Teghaza 001 suggest Mars’ surface had water at more than 4.1 billion years ago,” making the rock “a witness to a time when Mars was likely warmer and wetter than it has been for most of its history.” Co-author Lee Saper of NASA’s Ames Research Center calls it “really our first piece of Martian crust from a part of Mars we’ve never had a sample of before,” and one of the paper’s reviewers called it a Rosetta Stone for Mars. Saper is careful, though: the findings support the idea that early Mars had the ingredients for life, but “do not directly answer the question of whether there was life on Mars.”
That caution is earned. In 1996 another ancient Martian meteorite, ALH84001, found in Antarctica in 1984, made headlines around the world when NASA scientists suggested it contained microfossils, and a generation of SF writers dusted off their canals. The claim never won over the wider scientific community, though it did no harm at all to the paperback trade. Ray Bradbury, whose Mars was always a little warmer and wetter than the real one, would surely have enjoyed a rose-coloured stone from a lost Martian ocean landing in a desert. There’s no little green man inside this one, sadly. But it did travel a very long way to tell us the planet next door once had weather.
Image: NASA/JPL-Caltech.
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