Methane ice dunes spotted on Pluto

Abstract

NASA’s New Horizons spacecraft flew by Pluto in 2015, snapping photographs and collecting data that revealed the dwarf planet’s vast icy plains, towering mountains, and thin atmosphere. Closer inspection has possibly revealed a surprise: dunes (Science 2018, DOI: 10.1126/science.aao2975). Matt W. Telfer of the University of Plymouth and his colleagues make the case that dunes of methane ice grains stretch across several thousand square kilometers in the northwest lobe of a heart-shaped plain of nitrogen ice called Sputnik Planitia. If the researchers are correct, Pluto would join a small club, including Earth, Mars, and Saturn’s moon Titan, known to feature dunes. Telfer says that spotting the possible dunes—in photos taken when New Horizons was 12,500 km above Pluto—was relatively easy; explaining how they formed was harder. Spectroscopic data from the spacecraft suggested that the dunes are predominantly methane. The atmospheric pressure on the dwarf planet is just 0.001% that of