Mars may have been wet when rusted, decades of thinking

Scientists have discovered that Mars’ iconic rust-red appearance may have developed in a wet environment, challenging long-term theories about the history of the earth’s geological history than previously thought.

For decades, researchers believe that the red planet has obtained a unique hue from anhydrous hematite, an iron oxide formed under dry conditions. But a new study published in Natural Communications shows that the main mineral in Martian dust is actually iron rock, a hydrated iron oxide that usually forms in the presence of liquid water.

“Mars is still the red planet. It’s just our understanding of why Mars has changed,” explains Adomas Valantinas, a postdoctoral author at Brown University, who started the work at the University of Bern. “The main meaning is that because iron sulfates can only form when water is still present on the surface, so Mars is much earlier than we thought.”

The team came to this conclusion by combining observations from the European Space Agency (ESA) and NASA missions with new laboratory techniques, using different iron oxidation techniques to create Martian dust replicas.

“We tried to create a replica of Mars powder in the lab using different types of iron oxides.

Unlike previous studies that rely solely on spacecraft observations, the team used an advanced grinder to achieve about 1/100 of dust particles, which is about 1/100 of the width of human hair, matching the Ultrafine texture of actual Martian dust. They then analyzed the samples using the same spectral technique using the orbital spacecraft, allowing direct comparisons.

This finding contradicts the widely accepted model that proposes the Martian red formed by continuous oxidation in poverty-stricken conditions during the Amazon period, which has been around 3 billion years ago to the present.

Instead, it might have formed during the cold, wet period of Mars, probably during the Hesper period about 3 billion years ago, when volcanic activity was intense and could have interacted with liquid water or ice.

What makes this discovery particularly important is that iron sulfates remain stable on the Martian surface despite the planet’s current hyper-arc conditions. According to the researchers, the Furin aqueous solution may lose some adsorbed water while maintaining its poor crystallization structure, as evidenced by a 40-day laboratory dehydration experiment under simulated Martian conditions.

Colin Wilson, a scientist at ESA’s Trace Gas Orbiter and Mars Express project, highlighted the collaborative nature of the study: “This study is the result of a complementary dataset from international missions that explore Mars from orbits and on the ground.”

The team’s analysis attracted a variety of resources, including ESA’s Mars Express and Tracking Gas Orbital, NASA’s Mars Reconnaissance Orbital, and NASA’s Curiosity, Pathfinder and Opportunity Wanderer’s ground-based measurements.

The study also suggests that iron rocks in Martian dust may be associated with sulfates, which are consistent with the transition at the end of Hesperia.

A new understanding of the rusty appearance of Mars provides valuable insights into the climate history and potential residential nature of the Earth. The existence of Iron Man hydration shows that Mars experienced water changes before transitioning to its current desert state.

“We are eagerly awaiting upcoming missions such as the return of ESA’s Rosalind Franklin Rover and NASA-ESA MARS samples, which will allow us to explore more deeply about products that turn into Mars red.”

The Mars sample return mission may be particularly revealed because the samples collected by NASA’s perseverance rovers include dust, and once returned to Earth, scientists can accurately measure how much iron sulfate is.

For now, the ocher tone of the Red Planet continues to be admired from afar – but gains a deeper understanding of its water’s past.