Ancient Martian Meteorite Found in Sahara Dates Back Over 4 Billion Years
A meteorite recovered in Mali's Sahara Desert has been dated to at least 4.1 billion years old, offering new insight into Mars' early crust and water interactions.
Researchers funded by NASA announced that a meteorite recovered from the Sahara Desert in 2022 is at least 4.1 billion years old, making it one of the oldest known Martian rocks. The specimen, named Teghaza 001, was found near the Teghaza salt plain in Mali and identified as Martian by scientists at the University of New Mexico based on its oxygen isotope signature.
A team that included scientists from NASA's Jet Propulsion Laboratory, the California Institute of Technology, the University of California, Los Angeles, the University of New Mexico and the University of Maine used uranium-lead dating of zircon crystals and a rubidium-strontium laser technique to determine the rock’s age. The analysis also revealed that the meteorite interacted with liquid water around the same time, indicating that water was present on Mars during its earliest geological period.
"It was only after we started looking closely that we realized this meteorite is really unique," said Yang Liu, lead author and planetary scientist at JPL. "One of the paper's reviewers called it a Rosetta Stone for Mars."
"Right now, we are one of very few labs in the world able to perform this kind of age-dating, and the first to date such an ancient Martian meteorite," explained François Tissot of Caltech. "Our hope is to pave the way for dating even more Martian meteorites, or samples returned from other planets, their moons, and asteroids."
The mineral composition of Teghaza 001, which includes tiny zircon crystals and other igneous minerals, preserves evidence of both its original formation and later alteration by water. A separate study of hydrogen isotopes in the rock suggested that ancient Martian water had already begun losing hydrogen to space more than 4 billion years ago.
"This is really our first piece of Martian crust from a part of Mars we've never had a sample of before," said Lee Saper, second author of the study, now at NASA's Ames Research Center. "It records interactions of water and rock and maybe even an imprint of the Martian atmosphere as it was losing water."
Comparisons with data from the Mars Reconnaissance Orbiter highlighted 13 potential source regions, several of which lie in the heavily cratered southern highlands, but the exact origin remains uncertain. While the findings do not confirm past life on Mars, they provide valuable information about the planet's early environment and the role of water in shaping its crust.