Providence, Rhode Island – Scientists have discovered that Mars, often recognized by its distinct red color, has a wetter history than previously believed. By combining data from the European Space Agency (ESA) and NASA spacecraft with new laboratory experiments on imitation Mars dust, researchers have found evidence suggesting that Mars rusted early on in its ancient past, when liquid water was more prevalent.
Through decades of studying the Red Planet, scientists have determined that the red hue of Mars is due to iron minerals in the dust becoming rusted over time. The iron in Mars’s rocks reacted with either liquid water or water and oxygen in the atmosphere, similar to how rust forms on Earth, leading to the distinctive color.
Over billions of years, this iron oxide material, known as rust, has been broken down into dust and spread across Mars by winds, a process that continues to occur presently. The composition of iron oxide found on Mars has been debated extensively, as it provides insights into the planet’s past environmental conditions and whether Mars could have supported life.
Previous studies based solely on spacecraft observations suggested that the iron oxide in Martian dust did not contain water. Scientists had speculated that the iron oxide must be hematite, formed under arid surface conditions through reactions with the Martian atmosphere over long periods. However, new analysis utilizing spacecraft observations and innovative laboratory techniques indicates that the red color of Mars is better matched by iron oxides containing water, specifically ferrihydrite.
Ferrihydrite typically forms rapidly in the presence of cool water, implying that it would have developed when Mars still had liquid water on its surface. Despite being ground down and dispersed across the planet over time, the ferrihydrite has maintained its watery signature until the present day.
In a groundbreaking study, researchers created replica Martian dust in the laboratory by mixing ferrihydrite with basalt, a volcanic rock, which closely resembled the minerals observed on Mars by spacecraft. Their findings have significant implications, suggesting that Mars rusted earlier than previously thought and that ferrihydrite remains stable under current Martian conditions.
Further studies have confirmed the presence of ferrihydrite in Martian dust, with researchers utilizing a combination of space mission data and novel laboratory experiments to provide comprehensive proof. Advanced technology was employed to replicate the realistic grain size of Martian dust, similar to 1/100th of a human hair, allowing for detailed analysis and identification of ferrihydrite as the best match.
The collaboration between international missions exploring Mars from orbit and ground level has been instrumental in advancing our understanding of the planet. Ongoing missions, such as NASA’s Mars Reconnaissance Orbiter and the upcoming Mars Sample Return, are expected to provide additional insights into Martian mineralogy, history of water, and the potential for life on the Red Planet.
Moving forward, as we await the return of samples collected by NASA’s Perseverance rover, scientists anticipate further discoveries that will shed light on Mars’s past and present characteristics. The red hue of Mars will continue to captivate scientists and space enthusiasts as we unravel the mysteries of the Red Planet.