Astrobiologists from the Arizona Institute of Planetary Science have modeled subsurface flows of liquid water on Mars, revealing that narrow channels within frozen soil could be wide and stable enough to host microorganisms. The findings were published in Icarus.

A Mistake That Sparked Hope

Lead researcher Hannah Sizemore admitted that the team originally aimed to prove there was too little water to sustain life — but their calculations showed the opposite.

The scientists modeled how much liquid water could persist within icy Martian soil when mixed with salts that lower the freezing point. Even at −150 °C, briny soils could retain liquid water in microscopic pores.

Their models demonstrated that:

  • When soil contains about 5% water, channels as wide as 5 microns (ten times thinner than a human hair) can form.
  • These cavities are large enough for microbes to move and access nutrients.

Data from NASA’s Phoenix lander (2008) confirmed that such networks are likely present above 50° latitude.

Where to Search for Life

Sizemore noted that drilling just 30 centimeters might be enough to reach these watery veins.
These shallow subsurface networks are ideal targets for detecting biosignatures — accessible, shielded from radiation, and containing liquid water.

The key challenge, however, is the extreme cold (−50 to −70 °C). On Earth, extremophiles can survive down to about −20 °C, but potential Martian life might have evolved to tolerate much lower temperatures.

As planetary scientist Bruce Jakosky from the University of Colorado remarked, Earth’s limits are not necessarily universal.

What Future Missions Could Do

  • The ExoMars and Mars Sample Return missions may be able to collect samples from depths of 30–50 cm.
  • Future rovers equipped with spectrometers and microscopes could examine these channels for traces of organic compounds.

In Short

New models suggest that beneath Mars’ frozen surface lie microscopic water channels, about 5 microns wide, potentially capable of supporting microbial life. The most promising locations for exploration are regions above 50° latitude, just 30 cm below the surface. These findings challenge long-held pessimism and reopen the possibility that life on the Red Planet may still exist — hidden just beneath the ice.