By earthly standards, the surface of Mars is the image of devastation. Not only is it irradiated and cold enough to make Antarctica look bland, but it’s a thousand times drier than the driest places on earth. However, under the superarid surface of the Red Planet, there is abundant water ice that could one day be accessible to human explorers (and even settlers).
This is particularly the case in the mid-latitude region known as Arcadia Planitia, a smooth plain in the northern Mars lowlands. The region is showing signs of glaciers and glacier activity, according to new research conducted with support from NASA’s Jet Propulsion Laboratory (JPL). These results could prove very useful in future human landings and exploration of Mars, not to mention possible colonization.
The study, recently published in the journal Icarus, was led by Shannon Hibbard – a Ph.D. Candidate in Geology and Planetary Science from the University of Western Ontario (UWO). She was joined by Dr. Gordon R. Osinski of the UWO Institute for Earth and Space Research (IESE) and Etienne Godin, data scientist at Laval University’s Center for Northern Studies; and Nathan Williams and Matthew Golombek of NASA JPL.
MRO studies the water cycle of Mars. Photo credit: NASA / JPL / Corby Waste
Is there ice on Mars?
Speculations about the existence of ice on Mars go back centuries but remained uncertain until NASA’s Viking missions were the second and third missions to land on Mars in the 1970s. These indicated the presence of atmospheric water vapor and glacier-like features, which included widespread waves and accumulations of unconsolidated material (moraines).
These features are often associated with glacial landscapes here on earth. Since it has not yet been confirmed that Mars once had water on its surface, the scientific community cautiously referred to these features as “viscous flow features”. And since exposed water ice on Mars is sublimated by the low air pressure and solar radiation, the researchers suspected that these glaciers would need to be protected by a thick layer of regolith.
By 2002, sensor data obtained from the Mars Odyssey orbiter confirmed the presence of subterranean water ice in the mid-latitude region of Mars. These results were confirmed in 2008 by the Phoenix Lander, which identified the presence of subterranean water ice in the northern Arctic plain. Then came the Mars Reconnaissance Orbiter (MRO), which discovered abundant subterranean water ice beneath the flat plains of Arcadia Planitia.
The MRO’s ground penetrating radar indicated that this ice extended down from the surface (under a layer of dust and debris) to a depth of 38 meters (~ 125 ft). The data provided by these and other missions have collected data that has enabled scientists to map, catalog, and categorize thousands of features that are likely the result of glacial activity.
Underground water ice on Mars, cool colors are closer to the surface than warm colors. The outlined box is the ideal region for sending astronauts to dig for water ice. Credits: NASA / JPL-Caltech / ASU
Glaciers in the region
For their study, Hibbard and her colleagues mapped dozen of surface features in Arcadia Planitia and looked for the same “tortuous features”. They found waves and furrows in valleys and on slopes that are typical wherever ice flowed downhill. However, Hubbard and her team also found these features in a flat-lying region of Arcadia Planitia that was isolated from any cliffs or slopes.
This left only one possibility, namely that glaciers once flowed over these flat areas of the surface. As Hibbard explained in an interview with GlacierHub:
“It was very exciting to find possible flow features in this flat lying region. Previous studies have shown that there is a buried ice sheet at our study site, and our evidence of channeled ice in that ice sheet suggests that Mars has more complex glacier dynamics. “
To determine how this ice sheet would flow, Hibbard and her team compared the flow characteristics of Arcadia Planitia with similar characteristics in the ice flows of Antarctica – where regions in the flat ice sheet move faster than their surroundings. Although the researchers do not know the exact cause of these ice flows, they concluded that it could be due to a combination of subterranean topography and melting at the bottom of the ice sheet.
In the case of Arcadia Planitia, the ice sheet has since stopped flowing and has become a standing ice stream that accumulates a thicker layer of surface debris. These unique properties provide an important opportunity for future crewed missions to Mars. In short, could this water ices be made for human consumption?
Artist rendering from NASA HiRISE data of a medium latitude glacier on Mars isolated from a surface layer of dust and rock. The hotel is located on the Mesa Wall in Protonilus Mensae on Mars. Photo credit: Kevin Gill
Human rated missions
While most of the glaciers on Mars and their underground ice reside near cliffs and slopes, the Arcadia Planitia Glacier forms a temperate flat ice sheet that is near the surface. Additionally, geographic hazards (such as boulders and debris) are few, making it both an ideal landing site and a good place for in situ resource use (ISRU) on future human missions.
This distinguishes it from glacial fields that are closer to the polar regions, are easily accessible, but are extremely cold compared to the mid-latitudes. As Germán Martínez, a member of the Lunar and Planetary Institute (LPI), told GlacierHub in a statement:
“[I]In general, it is more practical to go to low and medium latitudes, where temperatures are milder and solar energy is available year round. However, in these middle and low latitudes, the water ice is usually deeper underground than in polar latitudes. “
In addition, the Arcadian ice studied by Hibbard and her colleagues may be more accessible than other known water ice deposits at medium Martian latitudes. So if crewed missions take place regularly on Mars, this ice can prove indispensable for astronauts and their habitats, supplying everything from drinking and irrigation water to raw materials for making fuel.
Over time, the underground glacier can be opened up for an even more ambitious purpose – like terraforming Mars! If Mars is ever to become a warmer, wetter planet (as it was billions of years ago), underground ice deposits like this are essential for the transition.
Further reading: Columbia Climate School, Icarus
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