Underneath the reddish top layer of the seemingly ordinary rock, a whole kaleidoscope of rather unexpected colours has been revealed. This is especially interesting considering where the rock lies – in a Martian crater, which by all accounts was once a lake.
The name of the crater Lake is telling. At least to all speakers of Slavic languages. It means ‘lake.’ Planetologists have established that this 49-kilometre indentation was left from the fall of an asteroid 3.8-3.9 billion years ago, that is, only 700 million years after the formation of Mars itself and the entire solar system, and soon filled with water.
To this day, the crater is adjoined by a whole system of winding extended structures, about which geologists are quite sure: they are riverbeds. That’s why they chose Perseverance for the Mars rover.
Since February 2021, the rover has already travelled 30 kilometres. From time to time, it leaves behind it, on the Martian surface, capsules with soil that it has extracted with its drill. It sinks to a depth of about six centimetres. This is already very promising in terms of searching for possible traces of extraterrestrial life: the soil protects against radiation, against which the surface of Mars is almost defenceless due to the extremely weak magnetic field of the Red Planet and its thin atmosphere.
In addition to the drill, Perseverance has other similar ‘weapons’ in its arsenal, only it does not penetrate deep, but scrapes off the top of the rock. This abrasive method of the rover recently impacted a curious stone lying near the mouth of the ancient river Neretva, which flowed into the lake.
From above it, as is common on Mars, ‘corroded’ from oxidised iron, but under the chipped fragments revealed areas of several different colours. NASA admitted that a particular surprise was the pale green patches.
As the researchers explained, this is the colour of reduced iron. On Earth, this is what happens when water seeps through the rock and triggers a reduction reaction in it. Scientists mentioned that sometimes this reaction occurs with the participation of microbes.
In addition, such marks can be traces of decomposition of organic matter, which created the conditions for recovery. In NASA complained that it was not possible to properly place the tools of the rover to study these greenish spots, so their composition has not been established.
In the fertile times of this crater ‘lake’ Martian atmosphere was as dense as the Earth’s, and the air warmed to plus 50 degrees Celsius. Not surprisingly, scientists wondered: did not have time to form at least the most primitive, single-celled life there? After all, traces of life have been found on Earth in rocks more than four billion years old.