Making a Splash on Mars

Another way to help keep water liquid - on Mars or Earth - is to keep it moving.

"If you know a hard freeze is coming where you live, what's the first thing you do?" asks Hoover. "You turn your faucets on a little to let water trickle out. This way your pipes won't freeze."

The same principle applies on Mars where salty water could be moving through subterranean aquifers. "Ice is a crystal," explains Hoover, "and it's harder to form crystals when the water is flowing."

Photos Courtesy Richard B. Hoover Sampling ice from a moulin in the tongue of Alaska's Matanuska glacier. Orange moss can be seen growing on broken rock debris on ice ledge

Hoover visited the Matanuska Glacier in Alaska to search for cold-loving microorganisms living in and around the ice.

"I chose the Matanuska Glacier to visit because it's accessible and has dark rock in contact with ice," says Hoover. "The sun shining on the rock causes the ice to melt. There are pools of liquid water where microorganisms grow in abundance. There is something very interesting and exciting about this picture of me taking samples from the edge of a moulin (a water-carved crevasse). Most of what we see is ice and the air temperature is below freezing, yet there is liquid water pouring out of the glacier. How is that possible? The water had broken free further back up the glacier where sunlit rocks melted the ice. Then it flowed beneath the ice until it broke through a hole in the wall of the ice. Everything the liquid water came in contact with was freezing, yet the moving water did not freeze.

"I have also seen liquid water running from snow melting on dark rocks heated by sunlight in Antarctica, even though the air temperature was below -20 °C."

There are many places on Earth where liquid water and ice co-exist in sub-zero conditions, says Hoover. The most famous example is Lake Vostok, an expanse of water roughly the size of lake Ontario lying 4 km beneath the Antarctic ice sheet. The ice sheet acts as a blanket, shielding the lake from Mars-like temperatures at the surface.

Will explorers one day discover oases like Lake Vostok beneath icy terrain on Mars? No one knows. But instead of "Follow the Water," the mantra of future colonists on the red planet might well be "Follow the Salt."

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