USGS: New Red Planet Map Shows Water Shaped Mars' Highlands

A small portion of the 118-megabyte new map of Mars' southern highlands published by the United States Geological Survey (USGS).

Credit: Scott Mest and David Crown/USGS

A very detailed new map of Mars' southern highlands shows how profoundly liquid water sculpted the region long ago, scientists say.

David Crown

"This new map depicts the complicated sequence of geologic processes that have served to modify ancient, rugged highland terrains surrounding the Hellas impact basin and shows evidence for the persistent effects of water and ice in degrading the Martian surface," David Crown, of the Planetary Science Institute (PSI) in Tucson, Arizona, said in a statement.

Crown and his PSI colleague Scott Mest produced the new map, which was published by the United States Geological Survey (USGS).

It covers the area on Mars from 27.5 to 42.5 degrees south latitude and 110 to 115 degrees east longitude.

Figure showing the area covered (crosshatched) by the USGS's new map of Mars' southern highlands.

Credit: Scott Mest and David Crown/USGS

The map sheds particular light on the evolution of two canyon systems in the southern highlands, Waikato Vallis and Reull Vallis.

Researchers think both canyons formed when underground water came to the surface, collapsing the ground.

Images from NASA's two Viking orbiters, which began circling the Red Planet in the 1970s, seemed to suggest that Waikato Vallis and Reull Vallis were part of the same ancient canyon system.

But the new map, constructed with data collected by NASA's Mars Reconnaissance Orbiter (MRO), Mars Odyssey and Mars Global Surveyor spacecraft, reveals that Waikato and Reull were actually separate canyons separated by a plains landscape known as Eridania Planitia.

In fact, water released from Waikato Vallis formed a shallow lake in these plains long ago, scientists said.

While Waikato and Reull are the dominant landforms in the area, the new map also shows many small channels that flowing water carved into the southern highlands, likely about the same time the two big canoyns were forming, researchers said.

"Most highland peaks and the walls of many impact craters show evidence that ice-rich sediments flowed downhill, forming features that resemble rock glaciers on Earth; these features represent the most recent water-related activity in the area, and may be active today," PSI representatives wrote in a description of the new map.

You can download a free copy of the 118-megabyte Mars map from the USGS website.

Mars crater may actually be ancient supervolcano

Seen above, for the basin and surrounding area, higher elevations (reds and yellows) and lower elevations (blues and grays) are indicated. Credit: NASA/JPL/GSFC

A research project led by Joseph R. Michalski, Senior Scientist at the Planetary Science Institute, has identified what could be a supervolcano on Mars – the first discovery of its kind.

In a paper published Oct. 3 in the journal Nature, Michalski and co-author Jacob E. Bleacher of NASA Goddard Space Flight Center describe a new type of volcanic construction on Mars that until now has gone unrecognized.

The volcano in question, a vast circular basin on the face of the Red Planet, previously had been classified as an impact crater.

Researchers now suggest the basin is actually the remains of an ancient supervolcano eruption.

Their assessment is based on images and topographic data from NASA's Mars Odyssey, Mars Global Surveyor and Mars Reconnaissance Orbiter (MRO) spacecraft, as well as the European Space Agency's Mars Express orbiter.

In the Nature paper Michalski and Bleacher lay out their case that the basin, recently named Eden Patera, is a volcanic caldera. Because a caldera is a depression, it can look like a crater formed by an impact, rather than a volcano.

"On Mars, young volcanoes have a very distinctive appearance that allows us to identify them," Michalski said. "The long-standing question has been what ancient volcanoes on Mars look like. Perhaps they look like this one."

Above, the dark color indicates younger material draped across the Eden Patera depression. 

Credit: ESA

The researchers also suggest a large body of magma loaded with dissolved gas (similar to the carbonation in soda) rose through thin crust to the surface quickly.

Like a bottle of soda that has been shaken, this supervolcano would have blown its contents far and wide if the top came off suddenly.

"This highly explosive type of eruption is a game-changer, spewing many times more ash and other material than typical, younger Martian volcanoes," Bleacher said.

"During these types of eruptions on Earth, the debris may spread so far through the atmosphere and remain so long that it alters the global temperature for years."

After the material is expelled from the eruption, the depression that is left can collapse even further, causing the ground around it to sink.

Eruptions like these happened in ages past at what is now Yellowstone National Park in the western United States, Lake Toba in Indonesia and Lake Taupo in New Zealand.

More information: www.nature.com/nature/journal/v502/n7469/full/nature12482.html