A meteorite recovered in the Sahara Desert has been dated to roughly 4.1 billion years old, making it one of the oldest Martian rocks identified so far. The sample, known as Teg 001, could offer a rare window into conditions on Mars during its earliest history, when the planet may have been warmer and wetter than it is today.
The research was led by Yang Liu of NASA's Jet Propulsion Laboratory and published in the journal Science. Co-authors Carl Agee and Karen Ziegler, from the University of New Mexico, worked on the analysis with Liu's team. Using uranium-lead dating on zircon crystals, the researchers arrived at the meteorite's age. Most other Martian meteorites collected on Earth are about 200 million years old, which makes Teg 001 an unusually ancient example.
Beyond its age, the rock stands out for its chemistry. Analysis of electron microprobe data and oxygen isotopes revealed high levels of manganese oxide, a compound of interest to scientists searching for signs of past life, since it can form in water-related environments. The rock also shows evidence that fluids and water once interacted with it, supporting the idea that parts of early Mars were more hospitable than they are now.
The team believes the meteorite likely originated in the ancient southern highlands of Mars, a region that rovers have not yet explored. That conclusion rests partly on orbital data, since the exact source area remains uncertain. Because Teg 001 is a single specimen, the researchers caution that broad conclusions should be drawn carefully, and similar samples are unlikely to turn up soon.