There is a reason why perseverance landed where it came from, and that reason dates back at least 3.5 billion years.
The first seas are believed to have been similar to Earth before solar radiation and other cosmic forces killed its atmosphere. This explains why the rover that has now gone viral on Twitterverse and almost everywhere touched the Jezero crater, which is believed to have been a large lake that could also have been crawling with microbial life. Now scientists have found evidence that Mars went through the same phase as Earth before both planets reached their atmosphere, something that has not been proven so far.
“Reduced greenhouse gases such as methane (CH4) and hydrogen (H2) could be the only sustainable solution to explain the warming of the ancient Martian climate, but there is a lack of direct geological evidence that an atmosphere existed. reduced to Mars, “said Jiancheng Liu, who led a study recently published in Nature Astronomy.
The timing for this discovery was right. Perseverance has begun to search the red planet for possible signs of life, and that life, if it were anything like what we know, would have required an atmosphere. But wait. Before you can find out when Mars began to get an atmosphere, and what it was like with an atmosphere (a little hard to imagine looking at what is now a space desert), you need to back up more until it was even oxidized environment. There was a time when things did not oxidize on Earth or Mars because there was not enough oxygen in the atmosphere to interact with iron-rich substances.
Instead of a rusty atmosphere, both Earth and Mars had a reduced atmosphere. This is not the same as the massive reduction in atmosphere that the red planet experienced after most of its atmosphere was decimated by solar winds and other cosmic forces. A reduced atmosphere is composed of mostly reduced gases such as methane, ammonia, and hydrogen sulfide, which are rich in hydrogen and not oxygen. Humans would not have been able to handle the breathing of this poison. However, there are methane-fed microorganisms right here on our planet, so it would not be impossible for Mars.
What made Mars habitable once was its own greenhouse effect. Although greenhouse gases have been demonized on Earth because too much carbon dioxide and other types have been released into the atmosphere by human pollution, the right amount of these atmospheric gases is needed. to warm the planet enough for life forms to thrive.
Previous studies had assumed that on Mars, this phenomenon occurred with reduction of gases instead of CO2, which means that the planet must have a reduced atmosphere. Finally, Liu and his team found evidence of this when they investigated data from spacecraft of weathered Martian rocks that showed signs of having been exposed to this atmosphere.
“The separation of Al Fe in Martian paleosols, which is comparable to the trends observed in paleosols before the great oxidation event on Earth, suggests that the ancient Martian surface was chemically weathered under a reducing greenhouse atmosphere.” , said Liu.
An orbiting spacecraft remotely examined the rocks on the surface of Mars. This probe was equipped with an instrument capable of infrared spectroscopy, which revealed the chemistry of these primordial rocks. When infrared light hits a target, it interacts with the molecules that make up that object. The way in which the object in question absorbs, reflects or emits this light can reveal what its chemical composition is. What the researchers wanted to know was the composition of paleosols on Mars, soils that formed eons ago and that have no physical and chemical relationship to the soils that formed most recently. Thus they identified a chemical sign of weathering caused by a reduced atmosphere.
Subsequently, Mars suffered a very large oxidation event from the large Earth-to-Earth oxidation event, albeit for a different time and possibly for different reasons. The Earth’s atmosphere oxidized because oxygen was a byproduct of processes such as the photosynthesis of early organisms. Demonstrating that Mars had a reduced atmosphere before its oxidation event occurred could mean that life was somehow involved in the change.
As Perseverence analyzes the Jezero crater, he may find more to support this discovery, and perhaps even a fossilized microbe.