Forgotten rock in a drawer is key to determining the age of water on Mars.

A meteorite from Lafayette, which is housed at Purdue University, has revealed key information about the history of water on Mars. This meteorite, which had been stored in a drawer for nearly a century, contains minerals that formed from interactions with water. Researchers have determined that these minerals date back approximately 742 million years, which is significantly more recent than previous estimates of the existence of oceans and rivers on the Red Planet.

Marissa Tremblay, an assistant professor at Purdue, highlighted that they have developed a robust method for dating altered minerals in meteorites, which can be applied to other planetary bodies to understand when liquid water may have been present. However, the research team does not believe that Mars was filled with water at that time; they suggest that the water could have been the result of melting permafrost, possibly due to the movement of molten rock through the Martian crust. This finding has been published in the journal Geochemical Perspectives Letters.

Scientists have explored this previous hypothesis regarding Mars' ancient climate. Computer models, based on the presence of specific minerals and rock formations, had already pointed to this possibility. Recently, NASA's Curiosity rover also provided data supporting this idea by analyzing rocks that suggest they formed under conditions of transient liquid water, meaning water resulting from melting ice.

The number of Martian meteorites available for study on Earth is scarce, with fewer than 400 known, and within the nakhlites, which are one of the three categories of Martian meteorites, there are only 32 recognized samples. The Lafayette meteorite is part of this rare group. Nakhlites are believed to have originated from a catastrophic event on Mars around 11 million years ago, which launched fragments of the planet into space, some of which eventually reached Earth.

In addition to investigating Martian history, a separate study has focused on determining how the Lafayette meteorite ended up at Purdue University. Researchers explored the meteorite's history and used forensic analysis to try to identify when and who might have discovered it over a century ago. Áine O’Brien, a researcher at the University of Glasgow, found unusual terrestrial contamination in a sample of the meteorite, related to a fungus that affects grain crops. This led to an investigation of disease outbreaks in crops that occurred in the region in 1919 and 1927, shortly before the meteorite was rediscovered in 1931.

The story also mentions that a Black student, whose name is unknown, witnessed the impact and collected the meteorite. Through records of meteor sightings, four possible students who could have found it during those years have been identified: Julius Lee Morgan, Clinton Edward Shaw, Hermanze Edwin Fauntleroy, and Clyde Silance. Scientists emphasize the importance of recognizing the discoverer of this rare meteorite, as its research value quickly diminishes when exposed to the terrestrial environment.

Finally, O’Brien expressed pride in being able to reconstruct the circumstances of the meteorite's landing while also working to identify the Black student who may have discovered it.