New details of Pluto’s moons Charon and Hydra are revealed in the latest images from the spacecraft’s Long Range Reconnaissance Imager, taken on July 13, 2015 from distances of 289,000 miles (466,000 km) and 400,000 miles (644,000 km), respectively.
This image of Pluto’s largest moon Charon was taken on July 13 from a distance of 289,000 miles. Image credit: NASA / Johns Hopkins University Applied Physics Laboratory / Southwest Research Institute.
The new view of Charon reveals a youthful and varied terrain, and New Horizons team members are surprised by the apparent lack of craters.
A swath of cliffs and troughs stretching about 600 miles (1,000 km) suggests widespread fracturing of the icy moon’s crust, likely the result of internal geological processes.
The image also shows a canyon estimated to be 4 to 6 miles (7 to 9 km) deep.
South of Charon’s equator, at the bottom of this image, terrain is lit by the slanting rays of the Sun, creating shadows that make it easier to distinguish topography. Even here, however, relatively few craters are visible, indicating a relatively young surface that has been reshaped by geologic activity.
In Charon’s north polar region, a dark marking prominent in New Horizons’ approach images is now seen to have a diffuse boundary, suggesting it is a thin deposit of dark material. Underlying it is a distinct, sharply bounded, angular feature.
New Horizons also observed the smaller moons of Pluto: Nix, Hydra, Styx and Kerberos.
Made from a distance of 400,000 miles, this image shows Pluto’s tiny potato-shaped moon Hydra. Image credit: NASA / Johns Hopkins University Applied Physics Laboratory / Southwest Research Institute.
A new sneak-peak image of Hydra is the first to reveal its apparent irregular shape and its size, estimated to be about 27 by 20 miles (43 by 33 km). The observations also indicate Hydra’s surface is probably coated with water ice.
Observed within Hydra’s bright regions is a darker circular structure with a diameter of around 6 miles (10 km). Hydra’s reflectivity (the percentage of incident light reflected from the surface) is intermediate between that of Pluto and Charon.
Future images will reveal more clues about the formation of this and the other moon billions of years ago.
“New Horizons has finally nailed the basic physical properties of Hydra. We’re going to see Hydra even better in the images yet to come,” said Dr Hal Weaver, New Horizons Project Scientist.
