Scientists have a pretty good idea of what the surface of Mars looks like. But what exactly this surface is made of remains a mystery.
Now scientists believe they have discovered a completely new mineral on Mars from an unusual layer of iron sulfate with a distinct spectral signature. In an article in Nature Communications published on August 5, astrobiologists led by Janice Bishop of the SETI Institute describe the discovery of an unusual iron hydroxysulfate compound around Valles Marineris, a huge canyon that stretches along the equator of Mars. Researchers suggest that water once flowed in this area, and the discovery of the new mineral may provide tantalizing clues about how and what natural forces shaped the planet’s surface — and whether life once flourished on Mars.
Sulfur, an element common to both Mars and Earth, often combines with other elements to form minerals in the form of sulfates. These minerals dissolve easily in water, but unlike Earth, Mars has consistently dry weather, which means that sulfates could have remained on the surface after the planet lost its water. Studying these minerals, therefore, could reveal important information about Mars’ early history.
Researchers studied sulfate-rich areas near Valles Marineris, paying particular attention to regions that “included mysterious spectral bands detected by orbital data, as well as layered sulfates and intriguing geology,” Bishop explained in his statement.
In one area, they discovered layered deposits of polyhydrated sulfates, beneath which were monohydrated and hydroxysulfates of iron.
They tried to recreate them in the laboratory and found that the iron hydroxysulfate seen on Mars could only have formed in the presence of oxygen, and that the reaction required to produce this compound results in the formation of water. Furthermore, this could only have happened at high temperatures, the researchers say, suggesting that the sulfates were formed as a result of volcanic activity. Moreover, its structure and thermal properties indicate that it is a completely new mineral.
“The material produced in these laboratory experiments is likely a new mineral due to its unique crystal structure and thermal stability,” Bishop said. “However, to officially recognize it as a new mineral, scientists must find it on Earth.”
