For years, we have been taught that Earth is unique for its abundance of water and that no other planet in our solar system contains liquid water — especially not Mars, due to its low atmospheric and temperature conditions, which make it unsuitable for harbouring liquid water.

Recently, this belief has been disproved, as evidence shows that water is indeed present on Mars. Earth is no longer the only planet in our solar system with liquid water.

This discovery paves the way for many sci-fi enthusiasts to develop extravagant theories and possibilities for what may concur, ranging from deadly viruses to frightening humanoid creatures lurking at the depths of Mars.

Did life exist on Mars?

Ever since the discovery of the ever-expanding dark void we call “space,” humans have pondered the question; ‘Does life exist beyond Earth?’ Although we cannot yet physically travel to other planets to answer this question directly, we’ve recently developed technologies that can help, such as the James Webb telescope, which orbits the sun. This telescope can assist in identifying chemical signs of life on a planetary scale. Even with such technology, however, we cannot obtain a clear and conclusive answer to our question.

Scientists have hypothesized that life may have once existed on Mars. Billions of years ago, Mars was more Earth-like and even hospitable, with warm temperatures and lakes. It’s a common misconception that the temperature on Mars is very hot due to its red colour, but in reality, it’s quite the opposite. Mars is an extremely cold desert, with temperatures reaching as low as -153 degrees Celsius. Since water is essential for life to exist, scientists are currently searching for fossilized signs of ancient life in rocks from the Jezero Crater on Mars, which was once a lake billions of years ago.

Water on Mars: Liquid gold

Although life has yet to be discovered on Mars, scientists have known about water on the planet for some time, primarily in the form of ice at polar caps or permafrost, permanently frozen ground, beneath its surface. 

For years, scientists presumed that all liquid water on Mars had been lost to space due to its extremely thin atmosphere. However, a 2024 publication in Proceedings of the National Academy of Sciences suggests otherwise. This discovery involved NASA’s Mars InSight Lander, which used its seismometer to detect underground movements. It measured seismic velocities that indicated the movement of groundwater through igneous rocks deep beneath the surface of Mars.

The data obtained from the seismometer estimates that the water exists approximately 11.5 to 20 kilometres deep beneath Mars’ surface, in an area referred to as the mid-crust. The amount of water is not to be taken lightly either. In most studies like this, the results may be underwhelming, and one might rightfully be pessimistic, assuming the scientists only discovered a small amount of water. In this case, however, it’s estimated that there is enough water to cover the entire surface of Mars with an ocean one to two kilometres deep.

The only issue that these results presented is accessibility. The water is located too deep in Mars’ crust to be accessed by astronauts. The deepest man-made hole ever dug on Earth is only 12.2 kilometres deep, and it took 20 years to reach that depth. Digging past this point was not possible because the temperature increased too much. While we may not be able to reach this water reservoir anytime soon, Michael Manga — a professor of planetary science at the University of California, Berkeley and one of the researchers conducting the study — suggests that this area on Mars “should, in principle, be able to sustain life.” 

More recently, astrobiologist Dirk Schulze-Makuch of the Technical University of Berlin in Germany suggested that NASA may have accidentally killed life on Mars in an attempt to study and discover it. This may sound absurd, but the theory’s premise is that, due to the differing environments and ecologies of Mars and Earth, there may have been life on Mars that adapted to thrive in dry conditions. 

However, this life could have been killed by experiments that involved taking samples and pouring water on them to test for Earth-like life conditions. If the conditions on Mars are extremely dry and cold, testing for life by adding water might not be the best approach, as potential microorganisms may not survive being flooded.

A sci-fi lover’s dream

Knowing that water is essential for life to exist, the sci-fi lover in me imagines all sorts of possibilities, ranging from an entire ecosystem beneath the surface of Mars — think Journey to the Center of the Earth or Godzilla’s Hollow Earth — to human-like aliens living below the surface. They don’t necessarily have to resemble the “little green men” that have become the stereotypical image of aliens, but can you imagine drones being sent to the depths of Mars only to capture eerie footage of terrifying, 10-foot-tall humanoid creatures? 

The scientist in me, however, realizes that the most probable life forms that could exist beneath Mars’ surface are microbes — such as bacteria — or at most, cockroach-like bugs. This could also be equally terrifying if we consider the implications of potentially pathogenic microbes that humans have never been exposed to. As for bugs, it would be frightening if we encountered a situation similar to the one depicted in Life where a tiny but extremely intelligent organism, dubbed “Calvin,” can easily siphon the blood from humans to use as a nutrient to grow stronger.

Overall, it’s not certain that no life exists on Mars. While intelligent life may not be present, microbial life is quite possible. If we consider this through the lens of evolution, it makes sense that, if Mars was once habitable and hosted life, some forms of that life may have adapted to the current conditions, which we perceive as uninhabitable. We once believed that no liquid water existed on Mars, but we have since found evidence to the contrary. Who’s to say we won’t discover signs of life on Mars a few short decades from now?