A fragment of rock that once arrived from Mars has preserved material that has remained almost unchanged since the birth of the Solar System. Until now, no Martian meteorite had shown a similar combination of age and composition. The discovery fills a huge gap in the geological history of the Red Planet. It suggests that a region deep inside Mars survived without being affected by later transformations.
A Rock from a Lost Era
The meteorite designated Northwest Africa 13441 was found in Algeria back in 2019, but its composition and age remained uncertain for a long time. Scientists at Boston College studied the sample, and the result proved unexpected, Phys.org reports. The fragment is approximately 1.273 billion years old.
Most Martian rocks that reach Earth belong to the group known as shergottites. Nearly all dated members of this group are young by planetary standards, at less than 600 million years old. The next oldest examples are already about 2.4 billion years old, leaving a gap of roughly 1.8 billion years between the two age groups. The new sample falls directly within that interval.
A Trace of Primordial Material
The greatest surprise was found in the fragment’s chemical composition. The ratio of neodymium isotopes in it is the same as that of the material from which the Solar System formed. A similar composition is found in chondrites, the oldest bodies that accreted from dust at the very beginning of Solar System history.
No other shergottite had shown this feature. This means that part of the Martian interior apparently remained unmixed with the rest of the planet for billions of years after its formation. The study was published in the peer-reviewed journal Geochimica et Cosmochimica Acta.
A Planet Without Moving Plates
The reason lies in the way Mars itself is structured. The planet formed extremely quickly, in less than 5 million years after the birth of the Solar System, and it does not have moving lithospheric plates.
On Earth, material from deep layers is constantly mixed because sections of the crust sink downward and later return to the surface through volcanic activity. As a result, finding primordial material here in an unaltered state is practically impossible. Mars did not experience this kind of mixing, and its interior has remained a natural archive of the earliest era.
What This Means for Science
Any fragment of Martian rock reaches us only after an impact blasts it away from the surface of the neighboring planet. Researchers therefore have only a limited selection of material to study: only about four hundred such samples have been found on Earth.
No mission has yet succeeded in returning Martian soil to Earth, so these chance discoveries remain the only Martian material that can be placed under a microscope in a terrestrial laboratory. Because of this, every newly discovered rock with an unusual composition carries disproportionately high scientific value.
The Boston College team’s research is continuing. Scientists plan to examine other isotopic systems in the same meteorite to determine how it is related to the rest of the known Martian rocks.
