This Meteorite Has Uncovered an Ancient Traces of Water on Mars

There is increasing evidence that Mars was once a wet and watery world, with lakes and oceans shaping its surface, leaving behind sediments that are now being carefully analyzed by rovers exploring the planet’s dry, dusty landscape. We know water existed on Mars, but determining exactly when, how, and where it went is more complex. However, a new clue has emerged: a meteorite ejected from Mars 11 million years ago and later reaching Earth has revealed that liquid water may have been present on Mars less than a billion years ago.

A fresh analysis of the Lafayette Meteorite shows that minerals inside it formed in the presence of water around 742 million years ago. This is a significant breakthrough in dating Mars’ aqueous minerals, suggesting that, at times, Mars may have still been damp. Geochemist Marissa Tremblay from Purdue University explains, “Dating these minerals helps us understand when liquid water existed on Mars’ surface in the planet’s past.“

Minerals in the Lafayette Meteorite, Including Iddingsite with Argon Inclusions, Provide Key Clues to Mars’ Water History

The minerals studied include iddingsite, a rock that forms from volcanic basalt in the presence of liquid water. The Lafayette Meteorite contains iddingsite, which also has argon inclusions, providing another clue.

While dating minerals can be tricky, technological advancements have made this process more accurate. Using radiometric dating, scientists analyze isotopes of argon to determine when the element formed. Argon is a product of potassium’s radioactive decay, and by measuring the amount of the isotope argon-39, researchers can calculate how long ago the rock formed.

Dating Water-Rock Reactions in Meteorites

In their study, the researchers used this technique on a sample from the Lafayette Meteorite to measure the time that had passed since water and rock interacted to form iddingsite. Despite the meteorite’s journey through space—where it was subjected to impact, heating, and atmospheric entry—the team was able to model and account for these temperature changes and confirm that they did not affect the age of the mineral formation.

These findings offer new insights into the timeline of moisture on Mars, suggesting that the presence of water aligns with a period of increased volcanic activity. While such activity appears subdued now, recent data from the Mars InSight lander has revealed ongoing geological processes beneath the surface.

Beyond Mars, the researchers’ methods could have broader implications for studying other planetary bodies in the Solar System, including answering the long-standing question of how Earth acquired its water billions of years ago. “We have demonstrated a reliable way to date alteration minerals in meteorites, which can help us understand when liquid water might have been present on other planets,” says Tremblay.

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