For decades, scientists have been trying to answer the question: does liquid water exist on Mars, and could life be possible there? Recent studies suggest that beneath the surface of the Red Planet, there may be a network of microscopic channels filled with liquid water, where, at least in theory, living organisms could survive.

Extreme Conditions on Mars

Mars is a cold and arid planet. The average surface temperature is about minus 60 degrees Celsius, and in the polar regions, it can drop as low as minus 150. The Martian atmosphere is extremely thin, and its magnetic field is almost nonexistent, leaving the surface exposed to intense ultraviolet radiation and charged particles. These harsh conditions make it difficult for organic compounds to persist and for organisms to survive in open areas.

Traces of Water in the Past

With the advent of space probes in the second half of the 20th century, scientists obtained the first detailed images of Mars. They discovered dried-up riverbeds, canyons, and sediment deposits, all evidence that liquid water once flowed across the planet’s surface in the distant past. Later, significant reserves of water ice were found both on and beneath the surface. However, the main question remained: is there liquid water on Mars today, which is essential for life?

The Role of Salts and Liquid Water

Mars is known for its extreme conditions: nighttime freezes and atmospheric pressure about 160 times lower than Earth’s make it nearly impossible for water to remain liquid on the surface—it quickly evaporates or freezes. However, the planet contains many salts capable of forming brines, which freeze at much lower temperatures than pure water. In laboratory conditions, some of these solutions remain liquid even at temperatures well below zero.

As a result, thin films or small puddles of salty water may form on Mars, staying liquid even in severe cold. According to some scientists, such brines could exist temporarily—either in protected niches on the surface (such as crater bottoms or shaded areas) or beneath a layer of soil.

New Hypotheses and Computer Modeling

The discovery of salts and the potential for briny solutions has led scientists to reconsider previous assumptions: if such structures form on or below the surface, then under certain conditions, liquid water could exist—and with it, microbial life.

An American team of planetary scientists led by Hannah Sizemore from the Planetary Science Institute in Arizona decided to investigate whether channels with liquid water could exist in the near-surface regions of Martian permafrost. Using data on the composition of Martian soil collected by NASA’s Phoenix lander in 2008, the researchers calculated how much ice could melt in the presence of salts that prevent water from freezing.

This phenomenon is well known on Earth: even in the coldest regions, tiny films and veins of salty water exist between ice and soil particles, remaining liquid at low temperatures.

Computer modeling showed that if salts are present in Martian soil, a small amount of liquid water—about 5% of the total mass—could form. This water could flow through extremely narrow channels no more than five micrometers thick, which is about ten times thinner than a human hair. Despite their microscopic size, these channels are large enough to accommodate a microbe and allow it to absorb the substances necessary for life from its surroundings.

Prospects for the Search for Life

According to calculations, extensive networks of water veins should be widespread at latitudes above 50 degrees. If microbial life does exist on Mars, these microscopic channels could be the ideal place to search for it.

However, this hypothesis has a weak point—the temperature. Even if the salts prevent the water from freezing completely, these subsurface veins may still be too cold for Earth-like organisms. Nevertheless, as American planetary scientist Bruce Jakosky from the University of Colorado in Boulder notes, we should not judge the potential for life on Mars solely by Earth’s standards. Over billions of years of evolution, Martian microbes could have adapted to local conditions and thrived in this environment.

The scientific article detailing these findings was published in the journal Icarus.