Not too long ago, the idea of exploring and potentially inhabiting Mars was left to the realms of science fiction writers and movie scripts. But recent advances in global space technology, both privatized and government-funded, have brought us closer than ever to understanding more about this mysterious red planet.

We know that there was previously water on Mars, which has led astronomers and other researchers to turn their focus to this planet as one that could potentially be habitable in the future. New findings from the European Space Agency and Roscosmos’s ExoMars Trace Orbiter add weight to this theory. The evidence of water vapor on Mars could have significant implications, proving that the planet was once habitable and could be again.

What Makes a Planet Habitable

Whether a planet is able to harbor life or not depends on a complex integration of factors, not limited to the planet alone. Features such as the characteristics of the planet, the system it’s included in, and the star that it orbits around all combine together to determine whether life-sustaining capabilities are formed. Since we know that our planet is the only one currently housing life in the vast network of space that we’ve been able to explore, it’s easy to extrapolate from there that integrating all of the right features at just the right time isn’t a simple occurrence.

To be habitable, a planet must be able to sustain life for a substantial time. Right now, as we understand life, this means that there has to be accessible, usable liquid water. Scientists have been trying to detect evidence of water on the planets that are visible with our advanced technology, but to do so, the water must be on the surface of the planet. This area is then termed the “habitable zone.”

Each planet has its own processes that encourage or add obstacles to habitability. If a planet orbits and rotates at a rate that keeps it at extreme temperatures, the chances of sustainable life are minimal. This exists on planets like Venus, Pluto, and Mercury, for instance, which allows scientists to confidently turn their focus away from looking for signs of life in those areas and laser-sighting Mars as the most likely candidate for habitation.

The Roscosmos’s ExoMars Trace Gas Orbiter

In 2016, the ExoMars Trace Gas Orbiter was the first of its kind in a series of missions jointly undertaken by ESA and Roscosmos, two global space agencies. One of the main goals of the missions was to understand how some of the atmospheric gases in Mars could demonstrate and impact potential biological or geological behaviors.

The finding of methane in Mars’s atmosphere is exciting to scientists because it is short-lived, so evidence of it shows that there must be an active source of it somewhere, either biological or chemical. On Earth, methane is released by organisms when they digest their nutrients and by geological processes as minerals oxidize.

The Trace Gas Orbiter was designed to specifically detect and characterize trace gases in the atmosphere so scientists can learn more about what has formed the planet. The Orbiter will monitor changes in the atmosphere throughout the seasons, evaluating composition and temperatures, mapping subsurface hydrogen, and looking for deposits of water-ice. But an unexpected finding of water vapor opens the door to a lot of new theories.

What Water Vapor on Mars Means

As the detection of leaking water vapor from Mars’s atmosphere, scientists begin to get a better understanding of what is hiding under the surface. We’ve seen evidence of water in the form of dried-out valleys and river channels that show liquid water may have been flowing there actively in the past. Currently, that water is thought to be stored in ice caps and underground. But traces of hydrogen detected in the Trace Gas Orbiter helps scientists see how water isotopes have changed over time and location. As we learn more about the evolution of water on the planet, we understand how the essential liquid has disappeared over time, giving us answers as to the habitability of Mars has changed.

The more information we have as to how the atmosphere shifts, morphs, and adapts, the more knowledge we have as to the feasibility of the future potential of Mars as a planet hospitable to life.