A new study conducted by the California Institute of Technology and the Jet Propulsion Laboratory (JPL) presented promising evidence that Mars contains a significant amount of water beneath its surface.
This study challenges the long-held hypothesis that Mars’ oceans escaped the atmosphere billions of years ago as a result of dust storms and the planet’s low gravity. Caltech’s paper arrives at an exciting time for the red planet, with two rovers touching down this year and multiple international research projects aiming to learn more about the history and structure of Earth’s nearest planetary neighbor.
According to Caltech, more than four billion years ago, Mars had enough water to cover the entire planet with an ocean upwards of 1,500 meters deep—enough water to fill half of Earth’s Atlantic Ocean. Just around a billion years later, all that water had disappeared, leaving the planet as dry as it appears to be today. Mars has a gravitational force about 2.6 times weaker (38%) than Earth’s, so scientists had long-theorized Mars’ vast oceans had been whisked off into outer space. However, Caltech proposes that anywhere from 30–99% of Mars’ water is trapped within minerals buried within the planet’s crust.
Earth’s tectonic activity means water trapped in the crust eventually gets recycled into the atmosphere through processes such as condensation and volcanic eruptions. In comparison, Mars is tectonically inactive, so water that’s trapped in the crust stays in the crust. Hence, the water that once existed on Mars is still there, scattered beneath the surface of the planet, condensed into billions upon billions of hydrated minerals.
“Atmospheric escape clearly had a role in water loss, but findings from the last decade of Mars missions have pointed to the fact that there was this huge reservoir of ancient hydrated minerals whose formation certainly decreased water availability over time,” said Bethany Ehlmann, associate director at Caltech’s Keck Institute for Space Studies, in a Caltech news post about the study.
Astronomers and physicists have chased Mars’ water for decades, launching rover after rover in pursuit of the Red Planet’s missing moisture. Mars is not only the closest planet to Earth, but also the most habitable planet outside of our own. Its climate is temperate, and although the planet can reach the freezing lows of minus 100 degrees Fahrenheit, the planet is ripe for human exploration and provides hope for a second planet for mankind to live on in the not-so-distant future.
Finding water on Mars would not only contribute to the habitability of the planet, but also inform us more about the history of life on the planet. Wherever water is, life follows. A single drop of water on Earth contains a kaleidoscope of diverse microorganisms, and discovering more information about the history of water on Mars could enlighten scientists on what kind of life forms used to or currently exist there.
“The surface of Mars today is extremely dry, but there are lots of clues pointing to a much wetter past,” said astrobiologist Alberto Fairen to NASA. “Evidence for past water may be the clue to follow to find extinct life on Mars and if some of that water still persists on Mars today, then for sure the prospects to find extant life go up.”
Mars also possesses a large amount of water frozen in its two polar ice caps, similar to Earth’s Antarctic and Arctic poles. Almost all of Mars’ water is frozen in ice due to the vast period of time the planet spends in sub-freezing temperatures during its orbit. Even if the water on Mars does not assist scientists in their pursuit to map the history of life on the planet, knowing more about its availability could greatly help future inhabitants of Mars. Although humans are unlikely to touch down on Mars before the 2030s, such a manned mission is closer than it’s ever been, and the potential for long-term life on Mars is highly dependent on the sustainability of liquid water on the planet.
The search for water on Mars isn’t just being conducted from the distance of our blue planet. The National Aeronautics and Space Association (NASA) successfully landed their fifth Mars rover, Perseverance, this past February, and China’s National Space Administration (CNSA) has their own mission, Tianwen-1, orbiting the red planet now.
Although both projects are more focused on the topology and geological structure of Mars, they still aim to locate water and record data about its presence on the planet. Tianwen-1 is projected to land between May and June of this year, targeting the vast plain of Utopia Planitia as its landing spot—an area supposedly rich with a subterranean lake of ice. The United Arab Emirates’ Hope orbiter is also contributing to the effort, gathering data about the atmosphere and meteorology of Mars. Scientists have been searching for water on Mars for a long time—and they’re closer to finding it than ever before.
“A fundamental question for [Curiosity] was whether Mars could have supported a habitable environment,” said Michael Meyer, lead scientist for NASA’s Mars Exploration Program in 2013. “From what we know now, the answer is yes.”