As late as the Martian modern age, groundwater near the surface could have existed.

Late Water: It’s possible that liquid water existed on Mars for longer than previously assumed. During rock analyses in the Mars plain Utopia Planitia, the Chinese Mars rover Zhurong detected evidence of this. Mineral crusts of hydrated silicates and sulfates were discovered there, which the team believes were formed by rising, saline groundwater. This suggests that liquid water has existed in the subsurface of Mars for the past 1.8 billion years.

In its early days, Mars had lakes, rivers, and perhaps even an ocean, making it more hospitable than it is today. However, how much liquid water existed on Mars and how long it lasted has been a subject of controversy. According to current beliefs, there were no persistent deposits of liquid water on the surface of Mars after climate change some 3.5 billion years ago. Even ephemeral water sources may have dried up by the time the Amazonian period began some 1.8 billion years ago.

Or not? Some theories say that even when Mars was cold and dry in the modern era, water could have come to the surface from hydrothermal vents or other sources of warmed groundwater. Riverbeds that cut through younger layers of rock are evidence of this.

Two different rock types

The Chinese Mars rover Zhurong may have discovered more evidence of “late” water. It was deployed by the Tianwen-1 Mars mission in May 2021 south of the Utopia Planitia plain, the largest impact sink on the Red Planet. The rover used six scientific equipment to explore the morphology, mineralogy, surface structure, and ice distribution surrounding its landing site during its 92-day mission on Mars. This data was evaluated by Yang Liu of Beijing’s National Space Research Center and his colleagues.

So, there are two different kinds of rocks at the spot where the rover landed. Dark basaltic boulders from older, deeper strata are found in the first. The second sort of rock, on the other hand, is light in color with a light coating on certain darker bits. According to studies, the light-colored crust is scaly and flaky, and it goes back to the Amazonian period, meaning it is less than 1.8 billion years old.

Crusts of hydrated silicates and sulfates

Spectroscopic investigation of the light-colored rock, on the other hand, indicated that it contained hydrated minerals, which are minerals with water bonded in their structure and are formed on Earth in the presence of liquid water. According to Liu and his colleagues, the spectral signatures of Martian rocks could be similar to those of hydrated silicates and sulfates, as well as gypsum.

They believe it is a type of duric crust, which are hard crusts generated by the precipitation of minerals from rock pore water, based on the light layers partially formed around dark cores. The researchers believe that the Martian crusts developed when saline brine rose underground during periods of greater groundwater levels. Evaporation from the adjacent surface increased the salt of the pore water, forming the saline mineral crusts.

Volcanoes or climatic warm phases

The Martian mineral crusts, according to the researchers, indicate that shallow groundwater existed as late as the Amazonian period. This rose high enough to soak the regolith and cause the duric crusts to form, at least momentarily.

“These observations suggest that aqueous activity on Mars has lasted far longer than previously thought,” Liu and his team write.

They believe that heat caused by volcanic activity, as well as transient warm periods caused by the Martian axis shifting, are probable causes for the late development of liquid water. This has varied its orientation by more than a dozen degrees during the course of Martian history, and consequently influenced regional solar radiation. Southern Utopia Planitia and other places may have had at least intermittent temperatures where saline groundwater remained liquid during one of these interglacial eras.

Water for future Mars astronauts?

However, the new results also have potential implications for future manned Mars missions: “The Zhurong landing site and other areas of the northern plains may contain significant amounts of usable water in the form of hydrated minerals and subsurface ice, which future Mars exploration will use as a pro… -place resource,” emphasizes the research team.

Image Credit: Getty

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