A couple of dozen missions have studied Mars. And they’ve told us a lot about the history of the Red Planet. We know that it was much warmer and wetter in the distant past. And there might have been pockets of warm and wet conditions much more recently. Those conditions could have supported microscopic life.

Future missions may target some of those locations. To know which sites might be most promising, scientists are looking at Mars-like locations here on Earth. They’re studying spots that are cold and dry, with chemistry that matches interesting Martian locations. That generally means high deserts with lots of ice.

One example is in the Andes Mountains of Chile. Scientists have studied a couple of patches of small lagoons. They’re frozen during winter, but thaw out in the summer. And they’re so high up that they get a heavy dose of ultraviolet light from the Sun — just as Mars does.

The lagoon regions contain rock layers that are much like those deposited on early Earth — and like many regions seen on Mars. The lagoons contain a variety of microscopic organisms that are like the oldest life on Earth. The similarity to some spots on Mars makes those locations more likely targets for future missions — spots that might preserve evidence of ancient Martian life.

Mars is climbing into the dawn sky. It looks like a moderately bright star, low in the east-southeast at first light.

More about Mars-on-Earth tomorrow.

Script by Damond Benningfield