Curiosity roverwhich investigates Gale crater on Marsprovides new information about how the climate on this planet has changed. Scientists used instruments on board the rover for analysis carbonateswhich serve as a very good record of past climatic conditions. It turns out that these carbonates were formed as a result of quite violent climatic processes, which suggests that liquid water could only exist on Mars for a short time.
David Burtt from NASA, lead author of the study published in the “Proceedings of the National Academy of Sciences”, explains that the examined samples they do not fit into an environment that might have formerly supported advanced life forms. However, this does not exclude the possibility of existence underground biosphere the short-lived, that existed on the surface before the formation of carbonates, although there is no clear evidence for this.
The isotopes of carbon and oxygen that formed carbonates provide very interesting information about the ancient climate of Mars. As the water on Mars evaporated, lighter versions of these elementsthey were running away” into the atmosphere, and heavier isotopes remained in the minerals. It is these heavier isotopes that are found in the rocks that Curiosity is now examining.
Scientists have proposed two main mechanisms for carbonate formation in Gale Crater. The first one assumes that they arose as a result a series of cycles of climate change from wet to dry. The second mechanism is related to the formation of carbonates in very salty water trapped under the icewhich would mean that most of the water was unavailable in the form of ice, and what remained liquid was extremely salty and inaccessible to living organisms.
There are quantities of heavy isotopes from Mars much higher than those we know from Earthwhich suggests that there were evaporation processes on the Red Planet much more intense. Scientists believe that it was necessary for these isotopes to be created the simultaneous existence of dry and wet cycles as well as extremely cold, salty conditions.
The research used advanced Curiosity instruments, including: SAM (Sample Analysis at Mars) i TLS (Tunable Laser Spectrometer). This allowed the samples to first be heated to almost 900°Cand then analyze the gases released during heating. Thus, the chemical composition of minerals that provide information about the ancient climate of Mars was examined.
Climate variability revealed by carbonate analysis suggests that the planet may have once had periods more favorable for the existence of liquid water. Nevertheless, these conditions were probably too dynamic to sustain life as we know it on Earth for long.
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Source: geekweek.interia.pl
