Why Mars "rusted": Scientists unveil the mystery of the Red Planet.

It is evident even from Earth that Mars is orange (or more simply, red). This distinctive color of our neighboring planet is due to iron oxides – rust scattered across its surface. Such popular perceptions, unchanged for nearly a century, are likely accurate, and no one is challenging them. Scientists have raised doubts about the "chemistry" of the so-called "dye."

A large group of European and American researchers (18 people) conducted experiments and concluded that Martian rust is quite different from what has always been believed. This suggests that Mars's geological past may also be different.

- Mars remains the Red Planet. Our understanding of what exactly gave it its color has simply changed, - explained Adomas Valantinas from Brown University in the US, the leader of the study featured in the journal Nature Communications.

The scientists diligently mixed various iron oxides with basalt and volcanic rock, grinding them until they produced dust that perfectly matched the color observed from orbit and in images taken by rovers on the surface.

Previous beliefs indicated that Mars was colored by dust primarily composed of hematite – an iron oxide that formed billions of years ago in a dry climate.

However, the best color match was achieved with another iron oxide – ferrihydrite. This mineral, with the formula Fe5O8H · nH2O, forms in a humid atmosphere and when liquid water is present on the surface.

If Mars indeed turned red due to ferrihydrite, it means the planet was once very wet. This is something that few doubt anymore – scientists regularly point to indirect evidence of water. They suspect that rivers, lakes, seas, and even oceans left these traces.

This could be how the bay of the Martian ocean looked, with traces of the coastline discovered by rovers – the Chinese (orange star) and the American (yellow star).

The question remains: "When did waves roll across the Martian seas?" There is no precise answer – it could have been billions of years ago or millions. Different scientists interpret the available data differently.

How accurate the current hypothesis about ferrihydrite is will be definitively known once Martian soil samples collected by the American rover Perseverance are brought back to Earth. For now, they remain on Mars, waiting in sealed containers. Most likely, the "return mission" will be a joint effort between NASA and ESA (the European Space Agency). It has proven too expensive for any single country.

- As soon as these precious samples reach the laboratory, – says physicist Colin Wilson from ESA, - we will be able to accurately measure how much ferrihydrite is in the dust and what it means for our understanding of the history of water and the potential for life on Mars.

BY THE WAY

Here are the fossils of inhabitants from Martian waters

Current research excites scientists who believe in the ancient Martian oceans and that life may have emerged in their coastal areas before the water vanished. They hope to "dig" through sedimentary rocks and find not only bacteria but also fossils of larger Martian organisms.

However, it is possible that these fossils were discovered two years ago.

On the 3786th Martian day of its mission, the "Curiosity" rover (NASA's Mars rover) photographed an object strikingly similar to the ribs of a skeleton – either of a fish or a marine creature.

A tweet from an astrobiologist featuring the "Martian fossil."

An astonishing image was found by astrobiologist Nathalie Cabrol. After posting it on Twitter, she wrote: "This is the most amazing rock I've seen in 20 years of Mars research."

To reassure those doubting it was a hoax, Nathalie linked to the official panoramic image. The researcher’s post attracted massive attention, garnering millions of views. Naturally, the astrobiologist intrigued many. However, she did not speculate on what the object resembling a large comb could be. That was left to social media users.

Most respondents considered the find evidence of past life on Mars and agreed that ribs of some skeleton were indeed protruding from the soil – exposed by the wind.

Skeptics recalled NASA experts' comments on images taken by the same Curiosity, which showed similar but smaller objects resembling earthly corals.

Experts explain that the "coral" and "stems" photographed on Mars are formed from sulfates – they were allegedly never alive.

Abigail Fraeman, representing the team that worked on the Curiosity project, explained on Twitter that the "corals" are mineral objects. That is, they are not alive. They are likely formed from sulfates that precipitated from water that once existed on Mars. Scientifically, such formations are called diagenetic crystalline clusters – structures consisting of a combination of several different minerals.

It is logical to assume that sulfates also formed the "skeleton." Initially, it was embedded in rock, which eroded over time. The structure itself appeared much stronger and, once exposed, remained untouched by erosion.

Enthusiasts are not very convinced by this explanation.