For greater than a decade, Colin Dundas, a geologist on the U.S. Geological Survey in Flagstaff, Arizona, has had a day by day routine: inspecting a dozen or so high-resolution photos beamed again day by day from the Mars Reconnaissance Orbiter (MRO). A number of years in the past, one thing stunning popped out from the planet’s sea of rust: a pale sliver of blue.
What Dundas noticed that day, and subsequently discovered at seven different websites, are steep cliffs, as much as 100 meters tall, that expose what seems to be almost pure ice. The invention factors to giant shops of underground ice buried solely a meter or two beneath the floor at surprisingly low martian latitudes. “This sort of ice is extra widespread than beforehand thought,” says Dundas, who, together with his co-authors, describes the cliffs this week in Science. Every cliff appears to be the bare face of a glacier, tantalizing scientists with the promise of a layer-cake document of previous martian climates and area lovers with a possible useful resource for future human bases.
Discovering ice on Mars is nothing new. Ice covers the poles, and a radar instrument on the MRO has detected signatures of thick, buried ice throughout the planet’s stomach. Some researchers prompt these deposits could possibly be the remnants of glaciers that existed thousands and thousands of years in the past when the planet’s spin axis and orbit had been completely different. However the depth of the ice and whether or not it exists as comparatively pure sheets or as granules frozen within the pore areas of martian soil have been unsure.
A decade in the past, researchers utilizing the MRO spotted a associated clue: swimming pools of seemingly pure ice within the flooring of small craters carved out by recent meteorite impacts. However it was unclear whether or not these frozen swimming pools had been related to the buried glaciers or had been merely remoted patches. On the ice cliffs, Dundas and his staff might see the glaciers in cross part, and so they patiently revisited the websites to see how they modified over time.
They discovered that the ice persevered via the martian summer season, when any ephemeral frost would have vaporized. And final yr, the MRO caught a number of boulders tumbling out of one of many cliff faces, suggesting that gradual erosion had launched them from an enormous ice deposit. Evidently the near-surface ice and the big subsurface deposits are one and the identical, says Ali Bramson, a co-author and graduate scholar on the College of Arizona in Tucson. “This deep, thick, pure ice extends virtually all the best way as much as the floor.”
Banding and subtly various shades of blue recommend that the slabs of ice are stacked. That suggests that the deposits constructed up over many seasons as layers of snow had been compressed in a earlier local weather cycle, says Susan Conway, a planetary geologist on the College of Nantes in France. Winds then buried the ice sheets in grit. “It’s the one cheap clarification,” she says.
Drilling a core from considered one of these deposits and returning it to Earth would provide a treasure trove of data to geologists in regards to the previous martian local weather, says G. Scott Hubbard, an area scientist at Stanford College in Palo Alto, California. “That preserved document could be of maximum significance to return to,” he says.
These websites are “very thrilling” for potential human bases as properly, says Angel Abbud-Madrid, director of the Heart for House Sources on the Colorado Faculty of Mines in Golden, who led a current NASA research exploring potential touchdown websites for astronauts. Water is an important useful resource for astronauts, as a result of it could possibly be mixed with carbon dioxide, the primary ingredient in Mars’s environment, to create oxygen to breathe and methane, a rocket propellant. And though researchers suspected the subsurface glaciers existed, they might solely be a helpful useful resource in the event that they had been no quite a lot of meters beneath the floor. The ice cliffs promise considerable, accessible ice, Abbud-Madrid says.
The cliffs are all discovered at latitudes about 55° north or south, nevertheless, which develop frigid and darkish within the martian winter—unpromising latitudes for a solar-powered human base. Because of this, the NASA research was restricted to websites to inside 50° of the equator. Now, Hubbard desires NASA’s human exploration program to search for comparable cliffs nearer to the equator. “What’s the cutoff level?” he asks. He hopes the following shock will probably be ice nearer to the martian tropics.