Recent studies suggest that ancient volcanic ash on Mars could hold clues to past extraterrestrial life. A newly identified rock type found at the future landing site of the ExoMars rover, scheduled for launch in 2028, may provide significant insights.
Researchers published their findings in the Journal of Geophysical Research: Planets, indicating that the rocks likely originated from airborne volcanic ash billions of years ago. Currently, no active volcanoes have been identified at the site.
The study indicates that dark rocks may have shielded mineral-rich layers beneath them, potentially preserving signs of life. However, the exact formation processes of these surface rocks remain unclear.
The research team mapped an area of 19,300 square miles (50,000 km²) using data from NASA's Mars Reconnaissance Orbiter, which has been searching for evidence of ancient water on Mars since 2006. It is theorized that dark rocks once covered the entire area but are now only found in small patches.
Researchers believe that the ash may have accumulated in lower areas within impact craters, where it mixed with groundwater. The team anticipates gaining further insights about the Oxia Planum site when the ExoMars Rosalind Franklin rover arrives on Mars in 2028.
Although the rover cannot traverse the rough dark rocks, the study suggests it may access mineral-rich deposits at the edges of these formations. The Rosalind Franklin mission has faced delays, partly due to the war in Ukraine, leading the European Space Agency (ESA) to sever ties with its former partner, Roscosmos, following Russia's invasion in 2022.
In May 2024, NASA rejoined ESA to complete the mission, having initially partnered on the project over 20 years ago before exiting due to budget constraints. The rover will drill into the Martian surface and collect samples from depths of up to 6.6 feet (2 meters) for analysis in its onboard laboratory.
Researchers are focusing on ancient rocks, believing they offer the best chance of finding signs of life. The dark rocks studied are thought to have formed during the Noachian and early Hesperian periods, approximately 4 to 3.7 billion years ago.
“These rocks are incredibly old, but this is precisely the time in Mars' history we want to investigate,” the scientists noted. “If life ever existed on Mars, it would have been a long time ago, as the planet has been dry and relatively inactive for the last three billion years. Thus, we aim to explore rocks from this period to see if there are traces of water or microbial life.”