As we can imagine, 4 billion years ago the Red Planet was very different from what we see today, not only from the geological point of view, but also from biological perspective. Scientists have longtime suspected that the fourth planet from the Sun was at some point in its history capable of sustaining life, at least in its basic form: microorganisms.

Two studies based on data retrieved by NASA’s Mars Reconnaissance Orbiter, one published last month in Nature Geosciences, and one appearing in the July 17 issue of the journal Nature, came to support the possibility of life on Mars somewhere in the planet’s distant past.

Billions of years ago, vast lakes, large rivers and other wet environments covered a significant area of the Red Planet, as the clay-like minerals or phyllosilicates now scattered across the Martian valleys, dunes and craters have suggested. Their presence points to an active role of water in the early geological era of Mars called the Noachian period, which dates back 4.6 to 3.8 billion years ago.

At a time when the Earth, as well as the Moon and Mars were all exposed to impacts with cosmic objects, the Red Planet sustained a wide variety of wet environments that may have been suitable for life.

Furthermore, the fact some rocks preserve traces of water flushing through create the premises for future Mars missions that can help us better understand the enigmatic planet, as John Mustard, member of CRSIM team from Brown University pointed out.

One of the things that shocked scientists the most was how pervasive water was on this planet, and how quickly and abruptly it disappeared. According to the study published last month in Nature Geosciences, Mars’s past river system eroded the clays formed in the highlands and concentrated them into an ancient crater lake, which is the best proof that standing water was present here for thousands of years.

The studies look at previous studies, which suggested that the high concentrations of minerals found on Mars constitute a harsh environment even for the toughest microbes, from an entirely new perspective: the salty deposits possibly followed a period when clay deposits and water may have sustained life.