Is there Life on Mars?

There is no definitive evidence to suggest that there is life on Mars, either past or present. While the idea has captured human imagination for decades and has been the subject of numerous science fiction works, scientific missions have yet to find conclusive proof of life on the Red Planet.  However, several aspects of Mars make the question particularly intriguing:

Historical Liquid Water

The discovery of ancient river valleys, polar ice caps, and signs of liquid water in the distant past have led scientists to consider that Mars was once a much wetter and possibly Earth-like environment where life could have potentially existed.  More recent observations suggest that liquid water might sometimes exist on the surface in the form of briny (salty) flows.

Methane Emissions

Methane has been detected in the Martian atmosphere.  While methane can be produced through geological processes, it is also a byproduct of life as we know it on Earth.  The observed variations in methane concentration on Mars have not yet been definitively explained.

Organic Compounds

The Curiosity rover discovered organic compounds in Martian soil.  While organic compounds are not necessarily an indicator of life (they can be formed through non-biological processes), their presence does indicate that some of the building blocks for life are present.

Extremophiles on Earth

Life exists in extremely harsh conditions on Earth, such as in acidic lakes, deep-sea vents, and even in radiation-soaked environments.  This resilience of life in Earth’s extreme environments expands the range of conditions under which scientists might expect to find life elsewhere, perhaps even on Mars.

Ongoing and Upcoming Missions

Numerous missions have been sent to Mars specifically to look for signs of past or present life.  The Mars 2020 mission, for instance, landed the Perseverance rover to look for signs of past life and collect samples that could eventually be returned to Earth for analysis.

The Search for Fossilized Microbes

One of the goals of current and future missions is to search for fossilized microbial life in the Martian rock record.  Even if Mars does not harbor life now, it may have in the past when conditions were more favorable.

Caution

It’s crucial to approach the question of life on Mars—or any celestial body—with rigorous scientific skepticism.  Cross-contamination from Earth, either from mission equipment or via meteorite exchange, is a potential issue that researchers are cautious to account for.

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