What is the importance of the presence of liquid water?
It is now widely accepted that Mars has a reasonably large volume of water.
However, the surface of the planet is so cold that this water only exists in the form of ice.
For life to exist on a planet, many scientists believe that it is essential that the world has liquid water.
Since technology has allowed humanity to look at Mars in detail, humans have been looking for clues about the presence of water on the red planet.
Did the water flow on the surface of Mars?
The Mariner 9 mission revealed evidence of water erosion in river beds and canyons, as well as traces of weather fronts and fog on Mars in 1971.
Subsequent missions by the Viking Orbiters, first launched in 1975, revealed even more details about how water flows on the surface and in the valleys.
Several studies have studied the presence of liquid water for decades. In 2000, the first evidence of liquid water on Mars was discovered.
It has been argued that the gullies observed on the surface of the planet should have been formed by the flowing water.
Scientists have cited the debris and mud deposits left as evidence of the presence of water moving at any given moment in the history of the red planet.
However, the formation of these gullies was hotly debated in the following years.
Ice proof in geological samples of Mars
Spirit and Opportunity, both rovers, found evidence of the presence of water locked in the rock in 2007, when one of Spirit's wheels shattered and gorged a piece Stone.
The analysis of the silica-rich layer found in the scratch suggested that it was formed in the presence of liquid water.
In 2008, the Phoenix Lander was taking geological samples that disappeared after a few days.
Scientists thought it was ice chunks. This assessment was confirmed when the undercarriage subsequently detected water vapor in a sample.
In 2012, Curiosity roamed an ancient Martian seabed by examining a number of rocks exposed to liquid water billions of years ago.
In 2012, Curiosity (photo) wandered on an ancient Martian seabed when he examined a number of rocks exposed to liquid water billions of years ago.
Linear recurrent slope and debate the cause
Features called Recurrent Slope Lines (RSL) were first identified in 2011.
These dark trails populate areas of Mars with a steep slope.
The researchers hypothesized that this may have been caused by the intermittent flow of liquid water along the steep banks of the planet.
In June 2013, Curiosity found strong evidence that water that was good enough to drink had once sank on Mars. In September of the same year, the first soil sample analyzed by Curiosity revealed that the fine materials on the surface of the planet contained 2% by weight of water.
In 2015, NASA said it had discovered the first traces of liquid water on Mars today.
The space agency said its Mars reconnaissance orbit (MRO) provided the strongest evidence to date that liquid water was flowing intermittently on the current Mars planet.
In 2017, NASA issued another statement in which it rebutted its original conclusions.
Features called Recurrent Slope Lines (RSL) were first identified in 2011 (photo). These dark trails populate areas of Mars with a steep slope. The researchers hypothesized that this could have been caused by the intermittent flow of liquid water
The dark features that descend on the steep slopes of the red planet are actually granular flows, where grains of sand and dust glide downhill to form dark streaks, rather than obscuring the soil by water seepage .
The MRO images revealed that the trails only existed on steep slopes so that the dry grains could descend as they do on the faces of the active dunes.
Also in 2017, scientists provided the best estimates for water on Mars, claiming that it once contained more liquid H2O than the Arctic Ocean – and that the planet has kept them more than 1 , 5 billion years old.
The results suggest that there was plenty of time and water for life on Mars to flourish, but over the last 3.7 billion years, the red planet has lost 87% of its water, leaving the surface sterile and dry.
An underground lake
In a study published in the journal Science, ESO researchers discovered the first concrete evidence of the presence of liquid water on Mars.
Using radar images from the Mars Express probe, the ESO team discovered a 12 km long underground lake filled with liquid water.