Locked beneath the surface of Mars are vast quantities of water ice, a new research has found.
In this week's issue of Science, researchers led by USGS planetary geologist Colin Dundas present detailed observations of eight Martian regions where erosion has uncovered large, steep cross-sections of underlying ice.
“What’s new and exciting here is that these ice sheets start quite shallowly,” says planetary scientist Colin Dundas of the US Geological Survey in Flagstaff, Ariz. That could be good news for future astronauts hoping to use that water to drink, or to create oxygen to breathe or make fuel for returning spacecraft.
It’s not just the volume of water they found, it’s how mineable it promises to be. The deposits begin at depths as shallow as one meter and extend upwards of 100 meters into the planet. The researchers don't estimate the quantity of ice present, but they do note that the amount of ice near the surface is likely more extensive than the few locations where it's exposed. And what's more, the ice looks pretty damn pure.
NASA calls the use of space-based resources “in-situ resource utilization,” and the agency thinks it will be essential to survival in deep space. Of particular interest to ISRU planners is the depth of the ice, and the ratio of pure ice to that mixed in with bits of Mars regolith. The more pristine the ice, and the closer it is to the surface, the less energy it takes to extract and use.
The ice found this time isn’t crystal clear. Over years, observations showed that the ice is slowly surrendering water to the atmosphere through a process called sublimation, and signs suggest that boulders and sediment are dislodging from the ice as it recedes. But some debris is to be expected. Dundas and his colleagues hypothesize that the ice originated as snow, falling in waves over millions of years. Some rocky material probably found its way in, in between snow events—but the surrounding ice, the researchers think, is relatively clean.
"On Mars, when you see something bright, it usually means ice,” says Richard Zurek, chief scientist for the Mars Program Office at NASA's Jet Propulsion Laboratory, who was unaffiliated with the study. Most of the material on Mars reflects little light, "but the albedo readings on these exposed sections show that this is very bright stuff," he says. "And the spectrometer readings support that this is water ice and not ice-cemented soil, which would be much harder to convert into water as a resource."
The cliffs are all found at latitudes about 55° north or south, however, which grow frigid and dark in the Martian winter—unpromising latitudes for a solar-powered human base. For this reason, the NASA study was limited to sites to within 50° of the equator. Now, Hubbard wants NASA’s human exploration program to look for similar cliffs closer to the equator. “What’s the cutoff point?” he asks. He hopes the next surprise will be ice closer to the Martian tropics.