A rare meteorite from Mars is giving scientists a new look at a mysterious period in the Red Planet’s history.
Researchers at Boston College have found that the rock formed about 1.27 billion years ago and may have come from a part of Mars’s deep interior that remained largely unchanged for billions of years.
The meteorite, known as Northwest Africa 13441, or NWA 13441, was discovered in Algeria in 2019.
The new study, published in Geochimica et Cosmochimica Acta, suggests that the rock is unlike any other Martian meteorite scientists have studied.
Martian meteorites are extremely valuable because researchers do not yet have large collections of rocks brought directly back from Mars. These meteorites were blasted off the planet by powerful impacts and eventually landed on Earth. Only around 400 Martian meteorites have been identified.
Many belong to a group of volcanic rocks called shergottites. But there has long been a strange gap in their ages. Most dated shergottites are younger than 600 million years, while another group dates to around 2.4 billion years ago. Scientists therefore had almost no shergottite samples covering roughly 1.8 billion years of Martian history.
NWA 13441 falls directly inside that missing period.
Using highly precise isotope dating methods, the researchers determined that the meteorite crystallized about 1.273 billion years ago. This makes it the first known shergottite from this poorly represented era and provides new evidence about volcanic and geological activity on Mars at the time.
But its age was not the only surprise.
The researchers also studied neodymium, a rare element that occurs naturally in several different isotopic forms. The meteorite’s neodymium signature closely matches the composition thought to have existed when the solar system first formed about 4.56 billion years ago.
Scientists call this a “chondritic” composition because it resembles the chemical signature found in primitive meteorites called chondrites. Such a signature has never previously been observed in a shergottite.
The discovery suggests that somewhere deep inside Mars, a reservoir of ancient material may have survived relatively untouched since the planet’s earliest days.
Mars formed remarkably quickly—within about 5 million years of the solar system’s birth. Unlike Earth, however, Mars does not have active plate tectonics constantly recycling its crust and mantle. That may have allowed some ancient material deep inside the planet to preserve its original chemical characteristics for billions of years.
The meteorite therefore offers scientists something like a geological time capsule. It not only fills a major gap in the record of Martian volcanic activity but could also reveal how the planet’s interior formed and changed.
Researchers now plan to study additional isotope systems in NWA 13441 to determine how this unusual rock fits into the broader story of Mars and its ancient interior.
Source: KSR.
