The Red Planet’s iconic rusty dust has a much wetter history than previously assumed, find scientists combining European Space Agency (ESA) and NASA spacecraft data with new laboratory experiments on replica Mars dust. The results suggest that Mars rusted early in the planet’s ancient past, when liquid water was more widespread.

However, new analysis of spacecraft observations in combination with novel laboratory techniques shows that Mars’s red colour is better matched by iron oxides containing water, known as ferrihydrite. Ferrihydrite typically forms quickly in the presence of cool water, and so must have formed when Mars still had water on its surface.

  • jol
    10·
    22 hours ago

    Did you read the article? We know it’s rust, but there are many forms of iron oxide that form in different conditions.

    Previous studies of the iron oxide component of the martian dust based on spacecraft observations alone did not find evidence of water contained within it. Researchers had therefore concluded that this particular type of iron oxide must be hematite, formed under dry surface conditions through reactions with the martian atmosphere over billions of years – after Mars’s early wet period.

    However, new analysis of spacecraft observations in combination with novel laboratory techniques shows that Mars’s red colour is better matched by iron oxides containing water, known as ferrihydrite.

    • AnIndefiniteArticle@sh.itjust.works
      41·
      17 hours ago

      You know, that is an important clarification, thank you.

      The water content in the rust and what that means for the formation conditions are really important and exciting!

      I was trying to emphasize that the iron oxide part has been known for millennia. The technique of trying to compare materials based on their color is older than civilization, though our methods have gotten a bit more precise in recent centuries. I was trying to humanize the act of spectroscopy into something most people were familiar with. In doing so, I left out the discovery of water that made this new research so exciting.

      The fact that there is also plenty of water in the dust is an important new discovery, both for understanding how the dust formed and for understanding the current water budgets and cycles on Mars. I wonder how easily that water gets exchanged between the dust, atmosphere, and subterranean reservoirs. I wonder how the dynamic distribution of water interacts with Martian weather, including its global dust storms and the large seasonal atmospheric pressure variations.

      • jol
        3·
        16 hours ago

        It’s the ol’ gaussian curve meme:

        1. Mars is a ball covered in rust
        2. Nooo, Mars is a planet covered in dust storms
        3. Mars is a ball covered in rust