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Evidences of Oasis Found On Mars, Strengthening The Case of 'Martian Life'

Pieces of evidence of oasis have been found on Mars, thus strengthening the case of a Martian life

NASA's Curiosity rover has found the signs of salty lakes and oasis on Mars dating around 3.5 billion years ago. These pieces of evidence have strengthened the case of life on the Martian land.

On Monday, a study titled "An interval of high salinity in ancient Gale crater lake on Mars" was published in Natural Geoscience. It was published by the scientists who handle and study the Curiosity rover findings. The results of recent studies baffled the layman and excited those who are interested in astrophysics. The article concludes that around 3.5 billion years ago, Mars had salty lakes and oasis.

This article has put the speculations of a Martian life on a whole new level. NASA's Curiosity rover recently tracked through Mars' Gale Crater and has found evidence of an oasis at the base of a 150 km wide crater. The article says that Mars likely underwent alternating periods of wet and dry, before becoming the frigid, dry desert it is now.

The researchers have studied the Curiosity rover's findings of traces of salts that resemble ancient brines. The rocks of the crater region have been enriched by minerals which are evidence of brines flowing through the period of drying out and overflowing. They commented, "The deposits serve as a watermark created by climate fluctuations as the Martian environment transitioned from a wetter one to the freezing desert it is today." These geological changes left a deposit of these minerals.

The transition initially happened from large on the surface lakes of salty water to ponds and oasis. And ultimately the climate of Mars changed from a wet one to an ice desert which is the current state of Mars. According to a statement from NASA’s Jet Propulsion Laboratory, the next step in their research is for scientists to understand how long the transition took and when it happened.
Lead author of the article, William Rapin of Caltech, who studies the Curiosity rover's findings, said in a statement, "We went to Gale Crater because it preserves this unique record of a changing Mars. Understanding when and how the planet’s climate started evolving is a piece of another puzzle: When and how long was Mars capable of supporting microbial life at the surface?”
The same bunch of researchers had found salts across a 150m tall section of sedimentary rocks called Sutton Island which Curiosity examined in 2017. Rapin said, "The Sutton Island salts are different: For one thing, they’re mineral salts, not table salt. They’re also mixed with sediment, suggesting they crystallized in a wet environment – possibly just beneath evaporating shallow ponds filled with briny water." Scientists have linked these similar salts to a nearby location of lakes in South America's Altiplano. Steams and rivers flowing from mountains caused basins similar to the recent findings on Mars. All these lakes are similarly influenced by climatic changes. 
The team of researchers is now seeing a cycle of wet-to-dry across long timescales on Mars. Scientist Ashwin Vasavada said, "As we climb Mount Sharp, we see an overall trend from a wet landscape to a drier one. But that trend didn’t necessarily occur in a linear fashion. More likely, it was messy, including drier periods, like what we’re seeing at Sutton Island, followed by wetter periods."
Rapin and his colleagues have dated these findings around 3.5 billion ago which is near the Hesperian time period. The interesting part here is that these salts were not found earlier in such form or abundance in the older rocks examined by Curosity. Researchers conclude that these salts must have been formed due to the evaporation of the lake.
There is a hypothesis that during the Hesperian period (3.3 – 3.7 billion years ago), widespread volcanic activity and catastrophic flooding took place that carved immense outflow channels across the surface. It is an intermediate and transitional period in the history of Mars. Much of this water flowed to the northern hemisphere, where it probably began to pool, forming large transient lakes or potentially, an ice-covered ocean.
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