As you know, the surface of Mars has a slightlyreddish tones. However, NASA's Perseverance rover found "islands" of magenta among the rusty hues. At almost every site he visited, the Martian palette included purple-colored rocks. The enigmatic paint forms a thin, smooth coating on some rocks, while spatter-like spots appear on others. Some stones even look like they have been partially covered with purple glaze. Moreover, such a coating was found on rocks of all shapes and sizes. Even a tiny pebble has not escaped this “purple paint”. But how and why did this raid come about? Scientists do not have a definite answer, however, the answer may contain information about the past of the red planet, including the presence of life on it.
The chemical composition of purple spots on Mars
The purple Martian coatings on the rocks werefound in Jezero Crater, formed by a meteorite impact billions of years ago. Once it was filled with a lake, and now it is a typical Martian desert. The Perseverance rover landed in the crater in February 2021 and has been carefully studying it ever since. At almost every stop, spots of magenta appear on his images.
Since the rover is equipped with various modernequipment, it allows you to get answers to some questions now. In particular, Ann Ollila, a geochemist at Los Alamos National Laboratory, is studying purple coatings with her colleagues using the SuperCam camera. Its peculiarity lies in the fact that it can shoot a laser at a stone, and thereby vaporize a small part of the material. This makes it possible to determine its chemical composition with the help of sensors.
Each laser shot also cuts out a tinya hole in the surface of the rock, this produces a sound similar to a click, which is picked up by a microphone. This sound allows scientists to get some idea about the properties of the stone, such as its degree of hardness.
The results of the raid study showed that itsofter than the rock below it, and also differs from it in its chemical composition. According to scientists, the data obtained hint that the coating contains various types of iron oxide, enriched in hydrogen, and sometimes magnesium.
The presence of hydrogen suggests that waterplayed a role in the appearance of purple spots. Iron oxide also indicates water. It is akin to rust, which forms on metal products left in the rain.
The Mystery of Martian Purple Rocks
According to scientists, they were puzzled by the veryarrangement of stones with a purple coating. The current route of Perseverance does not pass through lake sediments, but through rocks formed as a result of magma cooling. How the stones ended up in their current location at the bottom of the crater, as well as when and how the water came into contact with them, remains unclear.
So far, the team has analyzed only a fewsamples. In the process of their research, scientists have to face many problems. The chemistry of plaque and the laser sounds provided by the camera do not always match. Scientists also note that it is difficult to separate the chemical signatures that cover the rocks. Further complicating the task is the ubiquitous Martian dust, as well as strong winds, limiting the time scientists can hear laser clicks.
Subscribe to our Yandex.Zen channel, where you will find even more fascinating materials.
Traces of life on Mars?
On Earth, similar coatings on stones are also common.meet. They arise as a result of exposure to microbes. And this means that Martian stones with such a coating can be a real find for astrobiologists.
Nooks and crannies in rocks canserve as a safe haven for microbes in harsh Martian environments, providing them with nutrients, protection from the sun, and moisture in dry landscapes. Some of these microbes can metabolize metals removed from the surface of the stone or dissolved in water and form plaque. In addition, the coating may contain traces of ancient microbes that died many years ago, as it protects them from intense solar radiation.
It should be noted that the stones with plaque werefound not only in the Jezero crater. The first hints of rock coverings on Mars were discovered during the Viking missions that landed on the red planet in the mid-1970s. Since then, scientists have puzzled over their origin. Of particular interest was the discovery of dark, manganese-rich coatings in Gale Crater, where the Curiosity rover is currently active.
The find strongly resembles a special type of stonecover on Earth, which is usually teeming with tiny life forms. In a recent study of such plaque on terrestrial rocks, scientists found radiation-resistant bacteria. According to the researchers, the high content of manganese in the coating may be caused by a certain type of cyanobacteria. They concentrate the metal on the surface of the rock to protect it from harmful solar radiation.
Obviously, scientists will be able to get answers to all these questions only when the samples selected by the rover are delivered to Earth. I talked about how the delivery of samples will take place earlier.