Using images and data returned by NASA’s New Horizons spacecraft in 2015, members of the mission science team have created and published global topographic maps of Pluto and its largest moon Charon.
Led by New Horizons senior staff scientist Paul Schenk of the Lunar and Planetary Institute (LPI), the scientists embarked on the labor-intensive project by gathering all the images taken by the spacecraft’s Long Range Reconnaissance Imager (LORRI) and Multispectral Visible Imaging Camera (MVIC).
They then assembled mosaics for both worlds, carefully aligning surface features in overlapping images. For each region, the scientists used digital analysis of photos taken by both cameras to create topographic maps. These maps were then integrated into complete topographic maps for both Pluto and Charon.
Over the year-and-a-half during which New Horizons sent back its Pluto data, the researchers were able to create higher quality geographic and topographic maps.
In the final product, each area on Pluto and Charon lit by the Sun is depicted in the highest possible resolution. Individual elevations and the wide variety of terrains on both worlds are clearly visible.
On the Pluto map, viewers can see the steep, icy tops of the planet’s highest mountains, known as the Tenzig Montes range. Located to the southwest of the left side of Pluto’s heart feature, a nitrogen glacier known as Sputnik Planitia, these mountains have slopes of 40 degrees or greater. The tallest peak sits 3.7 miles (six km) above the mountain range’s base.
Tenzig Montes’s mountains are made up of hard water ice, the only ice powerful enough to hold them up. Other volatile ices on Pluto’s surface, such as methane and nitrogen ice, are not strong enough to hold up such structures and keep them from collapsing.
Several large-scale features not visible in the global mosaic map can be seen in the topographic map. Among these are differences in ice depth in the center versus the outer edges of Sputnik Planitia. Ice depth at the center of the 625-mile (1,000-km) glacier extends 1.5 miles (2.5 km) while at the outer edges reaches as far as 2.2 miles (3.5 km) below Pluto’s sea level, also known as its mean elevation.
Also visible in the topographic map are highly eroded areas of ridges and troughs stretching north to south for about 2,000 miles (3,000 km) close to Sputnik Planitia’s western edge. While this feature is considered evidence of ancient fracturing, scientists do not know why such fracturing would have occurred only in this one area.
Mountain ridges reaching heights between 2.5 and 3.1 miles (four and five km) are also seen on Charon. Scientists believe these formed when the large moon’s outer crust fractured as a subsurface ocean froze.
Fractured terrain and blocky regions may have been caused by cryovolcanism. Trouphs up to 8.7 miles deep (14 km) are seen near Charon’s north pole and in its equatorial regions.
Available for use by the scientific community and the public, the maps have been archived with NASA’s Planetary Data System.