A rose-coloured meteorite discovered in the Sahara Desert in 2022 has turned out to be one of the oldest pieces of Mars ever found on Earth. NASA-funded scientists have determined that the 800-gram rock, named Teghaza 001, dates back more than 4.1 billion years and could offer important clues about the Red Planet’s ancient crust and water history.
The meteorite was named after the Teghaza salt plain in Mali, where it was discovered. It is among roughly 435 Martian meteorites identified on Earth and is considered one of the three most ancient samples of the Red Planet found so far.
In a paper published in the journal Science on October 29, researchers presented an initial analysis of Teghaza 001, highlighting its unusual mineral composition and geological history. The findings offer a rare opportunity to study how Mars’ early crust formed and how water subsequently altered its rocks.
A separate study published in Science Advances in June examined the meteorite’s water content and provided further insights into how water shaped the planet’s early surface.
“It was only after we started looking closely that we realized this meteorite is really unique,” said lead author Yang Liu of NASA’s Jet Propulsion Laboratory (JPL) in Southern California. One reviewer of the paper described it as a “Rosetta Stone for Mars”, she added.
Teghaza 001 stands out because of its age, texture and unusual combination of igneous, or volcanic, minerals. Unlike other ancient Martian meteorites, its mineral composition offers a more detailed record of how the planet’s crust developed from cooling magma before being altered by underground water.
The other two among the three most ancient Martian meteorites found on Earth are ALH84001 and a sample nicknamed Black Beauty. ALH84001 is composed almost entirely of a single mineral, while Black Beauty formed around 2.1 billion years ago and consists of small volcanic rock fragments.
Researchers found that Teghaza 001’s mineralogy resembles features observed in Mars’ cratered southern highlands by NASA’s Mars Reconnaissance Orbiter. Although its exact origin on Mars remains unknown, the study identifies several possible locations that match its chemical and mineral characteristics.
“This is really our first piece of Martian crust from a part of Mars we’ve never had a sample of before,” said co-author Lee Saper, now a scientist at NASA’s Ames Research Center. He added that the meteorite records interactions between water and rock and could also preserve traces of the Martian atmosphere from a period when the planet was losing water.
NASA stated that researchers at the University of New Mexico had initially identified Teghaza 001 as a Martian rock by examining its oxygen isotopes, which act as geochemical fingerprints for different planetary bodies.
Further analysis revealed unusual textures and minerals, including zircon crystals that can help scientists determine when rocks formed and how they changed over time, the US space agency website said.
To establish its age, the team used an in-situ rubidium-strontium dating technique developed by Caltech co-author Francois Tissot’s team. Unlike conventional methods that require an entire sample to be dissolved and analysed, this technique examines individual mineral grains using a sample smaller than a fingernail.
The approach also preserves rare meteorite material for future research.
The results surprised the researchers. They found that Martian water had altered the rock around 4.1 billion years ago, suggesting Teghaza 001 itself originally formed even earlier.
Clues from its oxygen isotopes, texture and mineral chemistry point to a more dynamic water cycle on early Mars than previously understood.
Scientists hope further studies of the meteorite will reveal more about the Red Planet’s geological evolution, its ancient water systems and the processes that shaped its atmosphere. As Liu put it, researchers have only “scratched the surface” of what Teghaza 001 could reveal.
