NASA's New Horizons mission helped scientists identify the icy moons and the icy surface of Pluto. A new downlinked spectral observation of Pluto's moon Nix, from New Horizons, shows evidence that the moon's surface is also covered with water ice, just like another Pluto satellite, Hydra. Scientists believe that with the latest data will provide further clues of Pluto's satellite system.

New Horizons compositional spectral imager LEISA aboard the spacecraft contrasts Pluto's four small outer moons Styx, Nix, Kerberos and Hydra. From the data, it was observed that Nix' surface is made up of coarse-grained and pure water ice. 

"Pluto's small satellites probably all formed out of the cloud of debris created by the impact of a small planet onto a young Pluto," NASA project scientist Hal Weaver said in a press release.

The scientists also suggest that the water ice covering Pluto's moons could be made of similar materials due to the strong signature water-ice absorption pattern observed on all the surfaces of the three satellites. Although samples weren't collected from moons Styx and Kerberos, NASA said that the reflectivity suggests that they too are covered with water-ice surfaces.

The only difference on the surface of the moons is the depths of water ice absorptions. What baffles the scientists is the fact that Nix and Hydra have different ice textures despite the similarity in conditions and in size. Also, the reflectivity and visible wavelength of Hydra is higher than that of Nix, based on the data obtained by new Horizons Pluto flyby.

The high-resolution images were captured by LEISA aboard the New Horizons spacecraft from a range of 37,000 miles resulting to 2.3 miles per pixel resolution, according to Phys.org.

Aside from Pluto's icy moons, the New Horizons flyby in 2015 also resulted in fascinating findings including the discovery of Pluto's "beating" heart. The flyby also resulted to the most detailed image of the dwarf planet.