Source : NASA/JPL/Arizona State University
A potential Mars landing site could be underlain by debris-covered glaciers.
Strange sinuous features on a flat plain referred to as Arcadia Planitia bear a striking resemblance to ice streams within ice sheets in Antarctica, a latest study finds. If these shallowly covered glaciers do, in fact, exist, they might be a reason to direct future crewed missions to Mars toward the region. The spot was already intriguing to SpaceX and NASA because it’s a broad, flat plain, which is right for landing spacecraft. If there’s ice not too deep below the surface of the plain, astronauts could even have a water source easily at hand.
The newfound flow-like features are strange because they occur on flat terrain, said study leader Shannon Hibbard, a doctoral student at the University of Western Ontario in Canada.
“There’s many evidence that this is often an ice-rich area, but we don’t have any major topographic relief occurring where these sinuous features are,” Hibbard told Live Science. “They’re existing during a pretty flat-lying plane, in order that was quite odd.”
Mystery landforms
Arcadia Planitia is in Mars’ northern lowlands. In last 3 billion years, active lava flows smoothed over this region, in order that it’s far less pocked with craters compared with other parts of the earth . Data collected from orbit over the years suggest that the bottom within the region is rich in hydrogen. Because water is formed of hydrogen and oxygen molecules, this hydrogen suggests the presence of water ice right below the surface.
For decades, scientists have noticed features on Mars that look ice-related. Alongside low hills, there are aprons of debris referred to as lobate features due to their shape, which appear as if the outflow of glaciers covered in thin layer of rocks. There also are striated patterns within gullies that look almost like glaciers flowing through valleys on Earth.
Similar features occur in Arcadia Planitia, Hibbard said. Lobate features occur near a group of mountains referred to as the Erebus Montes that rise from the plain. Sinuous features snake through low-lying areas. She and her colleagues pulled together observations from multiple different instruments to try to spot these features. This included photographs from orbit, thermal data showing the temperature of the surface in both day and night, albedo data that reveals the reflectivity of the surface, information on the dust cover and data on elevation and topography.
Glacial flow
The sinuous features were the big mystery, Hibbard said, because they seemed like they were made by ice flow, but the terrain wasn’t steep enough to define why the ice would be moving.
“We had to try to find out what the heck are they, why do they need the thermal signatures that they have, why are they so bright in both day and night, why do they seem to possess flow features, why are they channelized, why do they occur near lobate debris aprons?” she said.
The analysis suggested that these features were, in fact, glacial in origin. The sinuous shapes looked almost like other features related to slow-flowing material seen on Mars, Hibbard said, and therefore the data suggested that these spots were indeed rich in ice.
What the sinuous features look most like, Hibbard said, is ice streams within ice sheets on Earth, which occur primarily in Antarctica. These faster-moving flows of ice aren’t well understood on Earth, Hibbard said, much less Mars, but they are doing show an example of ice flowing in fairly flat terrain.
This is a controversial claim, Hibbard said, because most ice streams on Earth require at least thin layer of liquid water at their base to lubricate their flow. It’s not clear whether subglacial water exists or ever existed on Mars, she said, neither is it clear whether a wet base would be required to cause ice streams to flow on the Mars. One possibility is that in past, when Mars’ orbit was tilted differently than it’s today and its climate was different, subglacial melt could have occurred.
“Ice streams are something which may get on Mars and might suggest more complex glacial processes have taken place on Mars, which i feel is basically interesting,” Hibbard said.
The next step, she said, is to research the terrain surrounding these sinuous features for more clues. Arcadia Planitia has never been studied except from orbit, but it’d be an exciting place to send future Mars missions, she added.
“It would be a intresting place to land not just for the accessibility of water ice and abundance of water ice, but also for the scientific value,” Hibbard said.
The research appears in journal Icarus.
