New high-resolution images show ice flow on Pluto’s surface

NASA’s New Horizons mission team have combined data from two instruments to create this composite image of Pluto’s informally named Viking Terra area. (Click to enlarge.) Image Credit: NASA / JHU-APL / SwRI

The first images released in 2016 of Pluto by NASA’s New Horizons mission team show the direction of flowing ice on the dwarf planet’s surface along with terrain patterns that suggest thermal convection is taking place on the icy surface of the area known as Sputnik Planum.

Combining images taken by the spacecraft’s Long Range Reconnaissance Imager (LORRI) from a distance of 31,000 miles (49,000 km) of features as small as 1,600 feet (480 meters) across with color photos taken by the Ralph Multispectral Visible Imaging Camera (MVIC) from a distance of 21,000 miles (34,000 km) at a resolution of 2,100 feet (650 meters) per pixel, mission scientists created a composite image (above) of a region to the left of Sputnik Planum known as Viking Terra.

Both the LORRI and MVIC images were taken on encounter day, July 14, 2015, with the MVIC photos captured about 20 minutes after those snapped by LORRI.

By overlaying MVIC’s color data on top of LORRI’s mosaic, scientists can see significant detail across the 160-mile (250-km) region, including crater rims covered with bright methane ices, layering along both crater walls and steep cliffs, and dark red tholins in low-lying areas. The bright ices likely condensed on the crater rims.

Tholins are small, dark particles produced by atmospheric reactions of nitrogen and methane. In Viking Terra, they are seen at the bottoms of craters.

Ices seem to have flowed toward channels and craters in areas that have the thickest level of red material along with smooth surfaces.

Subsurface flowing ice or surface winds could be moving the tholins, which usually do not move at the level of thickness seen on Viking Terra.

Evidence of flowing ice is also visible on a high-resolution LORRI image (right) showing the center of Sputnik Planum, the left side of the heart-shaped area known as Tombaugh Regio.

Within the icy plain separated into polygonal cells between 10 and 25 miles (16 and 40 km) wide, a small dark patch and thousands of tiny pits are visible.

To mission scientists, the cell patterns indicate the ices on Pluto’s surface are undergoing slow thermal convection.

Though at a lower elevation than surrounding terrain, the polygonal cells confirm Sputnik Planum is not entirely flat. Images taken from low-Sun angles, in which shadows are clearly visible, show the cells to have ridged margins and slightly elevated central areas.

The height of these central areas varies within a range of about 100 yards (or 100 meters).

William McKinnon of Washington University in St. Louis and deputy lead of New Horizons’ Geology, Geophysics, and Imaging (GGI) team, compared the slow thermal convection process taking place within Sputnik Planum with the movement inside a lava lamp.

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