Was There Life on Mars?

There is no conclusive evidence to confirm that life ever existed on Mars.  However, various missions and studies have found conditions that might have been conducive to life in the past, raising the intriguing possibility that Mars may have once harbored life forms.  Below are some key points that contribute to this ongoing debate:

Evidence of Past Water

Water is considered essential for life as we know it.  Mars shows ample geological evidence of past water flows in river valleys and lake beds, and polar ice caps are present.  The Curiosity Rover discovered rounded pebbles, indicative of ancient river flows, and Gale Crater is believed to have once contained a lake.  However, evidence of water alone doesn’t prove that life existed.

Organic Compounds

The Curiosity rover has also detected complex organic molecules on Mars.  While these are not evidence of life themselves—organic molecules can be formed through non-biological processes—they do suggest that some of the building blocks for life are present on the Martian surface.

Atmospheric Methane

Methane has been detected in the Martian atmosphere, which is intriguing because, on Earth, methane is often produced by biological processes.  However, methane can also be produced through geological processes, so its presence isn’t conclusive evidence for life.

Favorable Conditions in the Past

Studies suggest that Mars used to have a thicker atmosphere and liquid water on its surface, conditions much more favorable for life as we know it.  However, the planet has since lost most of its atmosphere, and the surface water has disappeared or become locked up in ice, making current conditions far less hospitable.

Extremophiles on Earth

Life exists in extremely harsh conditions on Earth, from acidic lakes to deep-sea hydrothermal vents.  The existence of extremophiles (organisms that thrive in extreme conditions) expands the potential range of planetary environments where life might exist or have existed, including Mars.

Search for Fossils

Current and future Mars missions aim to collect rock and soil samples that could contain fossilized remains of microbial life.  The Mars 2020 mission’s Perseverance rover, for example, has a primary goal of seeking signs of past life.

Potential Contamination

Scientists are cautious to avoid contamination of Mars with Earthly organisms, which would complicate the search for native Martian life.  Similarly, they aim to ensure that samples returned from Mars are handled with the utmost care to prevent any contamination that could affect the results of life-detection experiments.

Ongoing Research

The quest to find evidence of past life on Mars is ongoing.  Missions like the European Space Agency’s ExoMars and NASA’s planned sample-return missions aim to further investigate the Red Planet’s potential to have supported life.

Check out our 3D Mars Learning Center for more information on Mars.   You can also learn more at: NASA Mars Exploration.