A meteorite discovered in Mali’s Sahara in 2022 formed in the Martian crust at least 4.1 billion years ago, according to a study published in Science. Named Teghaza 001, it is likely the oldest of the 435 Martian meteorites recorded so far.
The coarse-grained rock, known as gabbro, contains mainly feldspar and pyroxene, as well as uranium-bearing zircon crystals. Researchers estimated its age by measuring how uranium decayed into lead over time.
Its chemical composition suggests that the rock interacted with water as it cooled and crystallized underground. Oxygen and hydrogen isotopes also indicate that water penetrated deep into Mars’s crust and mixed with molten rock from the mantle.
Planetary scientist Yang Liu, a co-author of the study at NASA’s Jet Propulsion Laboratory, said the meteorite offers evidence of a time when Mars was likely warmer and wetter than it was for most of its history. The findings suggest that water was present on the planet’s surface more than 4.1 billion years ago, though they do not establish whether life ever existed there.
Teghaza 001 was recovered as eight pieces in the desert, about 34 kilometers from the Malian village of Bir Chali. Researchers say its chemical makeup differs from that of other known Martian meteorites. It may have originated in the planet’s southern highlands, possibly near the Hellas Basin, one of Mars’s largest impact craters.
Only three known Martian meteorites date to the planet’s earliest history. One, found in Antarctica in 1984, was initially thought to be about 4.5 billion years old, but later estimates put its age close to Teghaza 001’s. The new study concludes that the Malian meteorite is probably older.
Co-author Lee Saper, a planetary scientist at NASA’s Ames Research Center and the Baer Institute, said the rock offers a snapshot of early Mars, when a wetter planet with a dense atmosphere may have had conditions suitable for habitability. He added that it also points to those conditions fading during roughly the planet’s first billion years. The findings do not answer whether Mars hosted life.
The meteorite was ejected from Mars by an impact and traveled through space before its path crossed Earth’s. It entered the atmosphere and survived its fall into the Sahara. Researchers do not know when it landed on Earth.
Sources: Folha Ciência.