Is There Water (or Life) on Mars?

Does new evidence show that liquid water could be present on Mars now? Does this mean humans might one day call the planet home?

Sabrina Stierwalt, PhD
4-minute read
Episode #164


NASA recently made an announcement that a major mystery from Mars had been solved and that an official announcement with more details would be made in a few days. Despite an accidental early leak of the press release, the big news was announced yesterday and set the astronomy community abuzz: planetary scientists have found evidence of liquid water on the surface of our neighbor, the Red Planet. What does this mean for the potential for life on Mars?

Why the Focus on Liquid Water?

Having not uncovered any evidence for its existence so far, we can be sure there is no other intelligent life in our solar system. Earthlings are hard to miss. We have been sending radio emissions out into space in the form of television broadcasts, satellite communications, and even radar to study other planetary surfaces for decades now. We would expect any other similarly intelligent civilizations to do the same. In fact, searches for intelligent life outside of our solar system have been largely focused on searches for radio emission.

Thus, the search for life in our own solar system is really the search for the potential for life. This potential could come in the form of more simplistic organisms like microbes, but it usually means looking for the conditions necessary to sustain life.  

Liquid water is required for the most basic processes that create and sustain life. The presence of liquid water thus directly assesses the chances that we could call a planet or other astronomical body “home.”

Water is surprisingly abundant in our solar system but usually in the form of water vapor on Venus or in the form of ice—for example in comets or distant Kuiper Belt objects far from the Sun’s heat. Even Mercury, the closest planet to the Sun, is able to sustain polar ice caps because they escape direct exposure to our star’s heat.

Until yesterday, the most promising hosts to liquid water in our solar system were Europa, one of Jupiter’s large moons, and Enceladus, a dynamic moon in the Saturnian system. Both moons show signs of having water below their icy crusts that is kept in liquid state thanks to hydrothermal activity caused by the tides due to their gas giant planetary hosts. Both also show evidence of erupting geysers, spewing that liquid water from below up and out over the surface.

But what about places a bit closer to home? So far, space travel has only taken humans as far as the Moon, much closer than the distances required to reach the outer solar system.


Please note that archive episodes of this podcast may include references to Ask Science. Rights of Albert Einstein are used with permission of The Hebrew University of Jerusalem. Represented exclusively by Greenlight.

About the Author

Sabrina Stierwalt, PhD

Dr Sabrina Stierwalt earned a Ph.D. in Astronomy & Astrophysics from Cornell University and is now a Professor of Physics at Occidental College.