Analyzes carried out by the US Perseverance rover on samples of volcanic rocks it collected on Mars, where it landed in 2021, indicate that they have been altered by liquid water, according to studies published this Thursday.
The robotic vehicle landed on February 18, 2021 in the Jezero crater, where there would be a lake and a delta (mouth of a river), as part of a mission carried out by the US space agency NASA.
Samples of igneous rocks (formed by the solidification of magma) were collected and analyzed by the robot from different areas of the crater floor, some deeper than others, which were subsequently altered by the action of liquid water, as explained by the authors of studies.
The studies, carried out from the data obtained by the robot, equipped with a drill and laboratory instruments, are reflected in four articles published in the scientific journals Science and Science Advances.
The rock samples, stored in tubes on the rover, will later be sent on another mission to Earth, where they are expected to arrive in 2033 for further analysis.
Both missions fit the purpose of searching for past microbial life on Mars, now an inhospitable planet. Liquid water is an essential condition for life as we know it.
According to one of the authors of one of the studies, David Shuster, a geochemist and professor at the University of California, in the United States, laboratory analysis of samples on Earth will allow scientists to date them and more accurately assess when the event occurred. what is now a crater lake and at what point “environmental conditions might have been conducive to life.
Some still open questions boil down to when the climate on Mars was favorable for the formation of lakes and rivers on its surface, and when it changed to today’s very cold and dry conditions.
Before the mission with the robot Perseverance (Perseverance), geologists thought that the crater was on the surface filled with sediments or lava (molten matter expelled by volcanoes and whose solidification, when cooled, results in volcanic rocks).
However, in two places, in an area of the crater identified with the name of Séítah, the rocks seem to have formed underground and during the slow cooling of a thick layer of magma (mass of molten minerals). Whatever covered these igneous rocks will have eroded away in the last 2.5 to 3.5 billion years, according to the scientists.
The Séítah rocks have a composition similar to some Martian meteorites, being composed mainly of olivine (a group of minerals abundant on Earth that can have a greenish color and have silicates of magnesium and iron).
From another area of the crater, called Máaz, igneous rocks were extracted that seem to have been formed by faster cooling and are richer in pyroxene (a group of minerals that contain silicates of magnesium, iron and calcium).
According to the authors of the studies published today, the Máaz rocks could have been part of the upper layer of a magma lake that filled the crater and slowly cooled, as they overlie the exposed rock layer in the Séítah area. .
Another accepted hypothesis is that the igneous rocks of Máaz may be the result of a later volcanic eruption.
According to the studies, both the Séítah and Máaz rocks present alterations produced by the effect of liquid water, although in a different way. The Máaz rocks contain pockets of minerals that may have condensed from brine (water saturated with salt) and the Séítah rocks reacted with carbonated water (water with carbon dioxide).
Source: TSF
