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Researchers in Canada recently discovered world’s oldest water dated nearly 2 billion years ago and while the discovery in itself is quite remarkable, researchers point out that the water may hold life and offer possible clues about life on Mars.

World’s oldest water was discovered in the same copper, zinc and silver mine wherein a previous expedition had led to discovery of water in 2013 that was 1.5 billion years old. Scientists say that the water is not different from what we find on other, the salinity is about eight times higher.

Despite this high level of salinity, the water could hold ancient microbial life and if that’s the case, it would have huge ramifications for astrobiology. Why? Because Mars may be holding underground water that is highly saline like the one found in the Canadian mines and if microbial life is present at such a depth in highly saline water, life on Mars could be possible.

Back in 2014, a team of scientists led by the University of Toronto’s Barbara Sherwood Lollar mapped the location of hydrogen-rich waters found trapped kilometres beneath Earth’s surface in rock fractures in Canada, South Africa and Scandinavia. Common in Precambrian Shield rocks – the oldest rocks on Earth – the ancient waters have a chemistry similar to that found near deep sea vents, suggesting these waters can support microbes living in isolation from the surface.

In the study published in 2014, the scientists also explain how two chemical reactions combine to produce substantial quantities of hydrogen, doubling estimates of global production from these processes which had previously been based only on hydrogen coming out of the ocean floor. Until now, none of the estimates of global hydrogen production sustaining deep microbial populations had included a contribution from the ancient continents. Since Precambrian rocks make up more than 70 per cent of the surface of Earth’s crust, Sherwood Lollar likens these terrains to “a sleeping giant, a huge area that has now been discovered to be a source of possible energy for life.”

One process, known as radiolytic decomposition of water, involves water undergoing a breakdown into hydrogen when exposed to radiation. The other is a chemical reaction called serpentization, a mineral alteration reaction that is common in such ancient rocks.

This study has important implications for the search for deep microbial life. Quantifying the global hydrogen budget is key to understanding the amount of the Earth’s biomass that is in the subsurface, as many deep ecosystems contain chemolithotrophic – so-called “rock-eating” – organisms that consume hydrogen.

In the deep gold mines of South Africa and under the sea there are hydrothermal vents where breaks in the fissure of Earth’s surface release geothermally heated waters – hydrogen-rich fluids host complex microbial communities that are nurtured by the chemicals dissolved in the fluids. This study identifies a global network of sites with hydrogen-rich waters that will be targeted for exploration for deep life over the coming years.

Further, because Mars – like the Precambrian crust – consists of billions-of-year-old rocks with hydrogen-producing potential, this finding has ramifications for astrobiology.

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