Two new studies point to a real possibility of life on Mars. We know Mars once had lots of water, enough water to cover the entire planet by as much as three-quarters of a mile. That water is now lost from the surface.
Artist’s
rendering of Mars before it lost surface water, credit NASA
One study, led by Eva Scheller, a planetary scientist at the California Institute of Technology, looked at the rate at which Mars lost water to space. Hydrogen, a component of water molecules, comes in various forms. Normal hydrogen consists of one proton and one electron. Deuterium, also called heavy hydrogen, also contains one neutron. Being heavier, deuterium can’t escape Mars as easily as normal hydrogen. By studying the ratio of the two, scientists can determine how much hydrogen, and therefore water, Mars lost to space since it formed. This allows the scientists to estimate the total amount of water Mars originally possessed.
Since the rate of hydrogen loss early in Mars’ history can’t be known precisely, scientists can only estimate the amount of water lost. They calculate that the total amount of water lost from Mars amounts to only enough to cover the planet by up to 82 feet. That leaves a lot of water still on Mars. The rest, they claim, went underground, chemically combined with minerals in the Martian crust. "Mars basically became the dry, arid planet we know today 3 billion years ago," Scheller stated. Since then, the amount of water locked below the crust has remained essentially unchanged. Water loss from Mars stopped when the remaining water became trapped in the crust.
Nathalie Cabrol, director of the Carl Sagan Center for Research, part of the SETI Institute, led the second study. She claims life would still exist on Mars if it ever developed there. It simply would have moved underground with the water. We haven’t found it yet because we haven’t looked in the right places.
Cabrol studies some of the harshest environments on Earth, locations scientists refer to as Mars analogs. These places represent the environments on Earth most like Mars, a cold, dry desert world. She explains that at these locations on Earth, “You can walk on the same landscape for miles and find nothing. Then, maybe because the slope changes by a fraction of a degree, the texture or the mineralogy of the soil is different because there is more protection from UV, all of a sudden, life is here.”
On Earth, virtually everywhere water exists, so does life, even deep below ground with water trapped in rocks. Cabrol says that on Mars, other conditions must also be considered. “What matters in extreme worlds to find life is to understand the patterns resulting from these interactions.”
Both scientists agree that the Perseverance Rover, newly landed on Mars, may be able to find the right conditions for Martian life below the surface.
Each month, I write an
astronomy-related column piece for the Oklahoman newspaper. On the following
day, I post that same column to my blog page.
