Scientists examining a rare meteorite discovered in the Sahara Desert found evidence that liquid water moved through Mars’ crust more than 4.1 billion years ago, providing new clues about the planet’s ancient environment and its potential to support life.
By yourNEWS Media Newsroom
A nearly 2-pound meteorite discovered in the Sahara Desert has provided scientists with some of the oldest physical evidence of water interacting with rocks beneath the Martian surface, suggesting that Mars experienced significant geological and water-related activity more than 4.1 billion years ago.
The meteorite, known as Teghaza 001, was discovered in Mali in 2022 and has now been identified as one of the three oldest Martian meteorites ever recovered on Earth. Its unusual mineral composition and evidence of ancient water exposure offer researchers a rare opportunity to investigate conditions on Mars during the earliest stages of the planet’s history.
The findings were published Thursday, Oct. 29, in the journal Science, in a study examining the meteorite’s ancient Martian origins.
The international research team, led by planetary scientist Yang Liu of NASA’s Jet Propulsion Laboratory, determined that the rock formed at least 4.1 billion years ago, when Mars was still developing its crust and geological structure.
According to NASA’s announcement of the findings, scientists discovered that the meteorite had been altered by Martian water approximately 4.1 billion years ago, indicating that the original rock formed even earlier.
“It was only after we started looking closely that we realized this meteorite is really unique,” Liu said. “One of the paper’s reviewers called it a Rosetta Stone for Mars.”
Teghaza 001 weighs approximately 800 grams and has a distinctive reddish-pink appearance. It was named after the Teghaza salt plain in Mali, near the region where it was recovered.
The meteorite is one of approximately 435 Martian meteorites identified on Earth, but its age and geological characteristics distinguish it from most other known samples.
Many meteorites originating from Mars formed during relatively recent periods of the planet’s geological history. Teghaza 001, by contrast, preserves evidence from a time when the planet was undergoing extensive volcanic activity and may have supported a more substantial water cycle.
Researchers determined the rock’s age by examining zircon crystals, minerals that incorporate radioactive elements during formation and can preserve evidence of geological events for billions of years.
Scientists used uranium-lead dating and a specialized rubidium-strontium technique to analyze the meteorite’s minerals.
The methods enabled researchers to determine when the rock formed and when subsequent geological processes altered its composition.
Francois Tissot, a geochemist at the California Institute of Technology and a co-author of the study, helped apply a relatively new dating technique that analyzes individual mineral grains rather than dissolving an entire sample.
The method allows scientists to preserve valuable extraterrestrial material while obtaining highly precise geological measurements.
“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,” Tissot said. “Our hope is to pave the way for dating even more Martian meteorites, or samples returned from other planets, their moons, and asteroids.”
The results revealed that Teghaza 001 contains mineralogical and chemical evidence of interaction with water deep within the ancient Martian crust.
Such interactions can occur when water circulates through rock formations, including areas affected by volcanic heat and subsurface geological activity.
According to University of New Mexico researchers who participated in the investigation, the meteorite’s mineral composition indicates that water was moving through the Martian crust billions of years before the planet developed its present cold and dry conditions.
Carl Agee, director of the university’s Institute of Meteoritics, said the meteorite provides an unusually direct record of Mars’ ancient environment.
“It’s the oldest Martian igneous rock ever found by a huge margin, but in addition to that, it seemed to have these clues in its composition that suggested it had been in an environment that had fluids and water coursing through it,” Agee said.
He explained that the sample differs from other ancient Martian meteorites because it consists of a single rock type rather than fragments of different geological materials.
That distinction allows researchers to study the rock’s original formation and subsequent alteration with greater clarity.
“It’s like going out, going back in time and chipping off a hunk of an outcrop, 4 billion years ago on Mars, and then we have this example of what was actually happening,” Agee said.
The rock is classified as a gabbroic diorite, a type of igneous rock that forms when molten material cools and solidifies beneath a planet’s surface.
Its mineral composition indicates that it originated from ancient magmatic processes, after which water altered portions of the rock.
Researchers also identified evidence that the water contained an unusual ratio of hydrogen isotopes.
An earlier study published in Science Advances in June examined the meteorite’s water content and found that its hydrogen isotope composition preserved evidence of Mars’ ancient water reservoirs.
Scientists measured the ratio of deuterium, a heavier form of hydrogen, to ordinary hydrogen and compared the findings with known characteristics of Martian materials.
The results suggested that water interacting with the rock had a deuterium-to-hydrogen ratio approximately twice that of Earth’s seawater.
That finding is significant because the relative abundance of the two hydrogen isotopes can reveal how water was lost from a planet over time.
Lighter hydrogen escapes into space more readily than heavier deuterium, meaning that water reservoirs can become enriched in deuterium as a planet loses atmospheric hydrogen.
The results support theories that Mars had already begun losing substantial amounts of water to space more than 4.1 billion years ago.
Researchers believe that the planet’s early geological history involved interactions among volcanic activity, subsurface water, its atmosphere and its developing crust.
Those processes may have produced hydrothermal environments, where heated water moves through mineral-rich rocks.
On Earth, hydrothermal systems can support microbial organisms by providing liquid water, chemical nutrients and sources of energy.
The discovery therefore adds to evidence that early Mars may have possessed some environmental conditions associated with habitability, although the meteorite does not demonstrate that life ever existed there.
Scientists have long suspected that Mars once contained rivers, lakes and other bodies of liquid water.
NASA’s orbiters and rovers have identified ancient river channels, sedimentary deposits and minerals that form through interactions with water.
However, accurately determining when those environments existed remains difficult because researchers have limited access to ancient Martian rocks that can be analyzed directly in laboratories on Earth.
Teghaza 001 offers an opportunity to study such material using techniques that cannot currently be performed by robotic spacecraft operating on Mars.
The new research also provides clues about where the meteorite originated.
Scientists compared its mineral composition with observations collected by NASA’s Mars Reconnaissance Orbiter, identifying 13 possible locations that share similar geological characteristics.
Several of those locations lie in the southern highlands, an ancient region containing heavily cratered terrain and geological formations dating to early Martian history.
Researchers believe the meteorite may have originated near the Hellas impact basin, although its precise source remains unknown.
The rock eventually reached Earth after a powerful impact on Mars ejected material from the planet’s surface into space.
That material traveled through the solar system before entering Earth’s atmosphere and falling to the Sahara Desert.
The exact date of its arrival on Earth has not been established.
Scientists determined its Martian origin by examining oxygen isotopes, which provide distinctive chemical signatures associated with different planetary bodies.
The composition matched that of other confirmed Martian meteorites, allowing researchers to distinguish it from ordinary terrestrial rocks.
Teghaza 001 is especially valuable because other ancient Martian meteorites provide different and sometimes more limited geological records.
One, Allan Hills 84001, was discovered in Antarctica and is approximately 4 billion years old. Another, Northwest Africa 7034, commonly known as Black Beauty, contains fragments of Martian rocks formed at different times.
Unlike those samples, Teghaza 001 preserves an unusually coherent record of ancient igneous activity and subsequent exposure to water.
“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, a study co-author who conducted the research at NASA’s Jet Propulsion Laboratory and now works 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.”
The meteorite is held in the collection of the Maine Mineral & Gem Museum in Bethel, Maine, which supported access to samples for scientific investigation.
In an announcement accompanying publication of the research, the museum emphasized the importance of preserving extraterrestrial specimens for continued study.
Scientists believe additional laboratory investigations could reveal more information about the conditions under which the rock formed, the temperatures involved in its alteration and the composition of the water that moved through Mars’ crust.
The research could also help NASA and other space agencies identify promising locations for future missions seeking evidence of ancient habitable environments.
Mars’ southern highlands have attracted scientific interest because their geological age makes them potential archives of conditions that existed during the planet’s earliest history.
The meteorite’s chemistry may help researchers interpret orbital observations and determine which regions contain rocks most likely to preserve evidence of water-related geological processes.
Liu and her colleagues expect additional analysis of Teghaza 001 to produce further discoveries about the development of Mars’ crust, mantle and atmosphere.
“We’ve only scratched the surface,” Liu said.
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