Thanks to observations from Mars rovers and space probes, we have known for decades that Mars once had water, and probably rivers and lakes. However, many questions remain. When did this precious liquid appear in the history of Mars? Has the red planet, during its evolution, brought together the conditions necessary for the emergence of life?
By analyzing the composition of a mineral (Zircon) found in a Martian meteorite, scientists from the University of Lausanne, Curtin University and the University of Adelaide have managed to date traces of water in the crust of Mars. According to this study, published in “Science Advances”, hydrothermal activity dates back 4.45 billion years, or only 100 million years after the formation of the planet.
“Our data suggests that there was water in the crust of Mars at a time comparable to the first traces of water on the Earth’s surface, around 4.4 billion years ago,” comments Jack Gillespie, first author of the study and researcher at the Faculty of Geosciences and the Environment at the University of Lausanne. “This discovery provides new elements to understand the planetary evolution of Mars, the processes that took place there and its potential to have hosted life.”
Scientists worked on a small piece of the meteorite NWA 7034 “Black Beauty,” discovered in the Sahara Desert in 2011. “Black Beauty” came from the Martian surface, and was thrown to earth during an impact on Mars about 5 to 10 million years ago. The analysis focused on zircon, a mineral contained in the meteorite. Very resistant, zircon crystals are key tools for dating geological processes. They contain chemical elements making it possible to reconstruct the conditions of its crystallization: the temperature, the interactions with fluids, but also the date.
“Zircon contains traces of uranium, an element that acts as a natural clock,” explains Jack Gillespie. “This element decays over time at a very specific and well-known rate, changing to lead. By comparing the ratio between uranium and lead, we can therefore calculate the age of crystal formation.
Using nanoscale spectroscopy, the team identified patterns of elements in this unique zircon, including unusual amounts of iron, aluminum and sodium. These elements were incorporated when zircon formed 4.45 billion years ago, and their presence suggests the existence of water during early Martian magmatic activity.
These new discoveries reinforce the hypothesis that the Red Planet may have provided favorable conditions for life at some point in its history. Which would include the presence of nutrient-rich hot springs. “Hydrothermal systems were essential to the development of life on Earth, and our results suggest that Mars also had water, a key ingredient for a habitable environment, during the earliest history of the formation of the crust,” comments co-author Aaron Cavosie from the School of Earth and Planetary Sciences at Curtin University.
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