We’ve known for years that there is at least some water ice on Mars, but it’s been hard to pin down where it is and how easy it would be to extract. New data from NASA’s Mars Reconnaissance Orbiter indicates there could be a lot of it in giant sheets that run for hundreds of meters hiding just below the surface. This could make future manned missions to explore Mars much more feasible.
The dusty Martian surface has proven adept at hiding the planet’s icy deposits. While several rovers and ground probes have studied Mars up close, they can only probe the top meter or so of the surface. Scientists have long suspected that any significant sources of water ice on Mars would be under the surface where they remain protected — from us and from the elements. Luckily, erosion happens on Mars just like it does on Earth. Using the Mars Reconnaissance Orbiter, NASA has spotted several places where erosion has revealed vast ice sheets (in blue above).
Using high-resolution images from the orbiter’s HiRISE camera, NASA has identified eight scarps (steep slopes) where thick layers of water ice are visible along the planet’s mid-latitudes. The team theorizes the ice was deposited in the past as snow before being compacted and obscured by the dust and rocks of Mars. Readings indicate the ice is relatively pure and several meters thick at least. Some deposits are believed to be as much as 100 meters thick. On top of the ice is a “cap” of ice mixed with rock and dust a few more meters thick.
NASA believes that access to water on Mars is essential to any long-term exploration plans. Every speck of matter you launch into space adds tremendously to the cost. Taking all the water necessary to sustain human astronauts adds significant complications. Water isn’t only for people — splitting the molecules into oxygen and hydrogen yields fuel that can be used for a return trip, saving even more on launch costs.
The search is on for more examples of these icy scarps. The eight identified by the Mars Reconnaissance Orbiter are between 55 and 60 degrees north or south of the equator. These regions of the planet get very chilly at night, so most missions stick to a narrow band around the equator. If icy scarps are found in those regions, it could be a boon to future human exploration. However, NASA worries deposits could be hidden deeper under the surface in these warmer areas. NASA’s 2020 rover will bring ground-penetrating radar to the red planet that might point scientists in the right direction.