The historic Pluto flyby by NASA’s New Horizons spacecraft has yielded a plethora of information, but the latest data concerning its moon Charon is the most startling. Images collected from the mission suggest that Charon, may once have contained a large subsurface ocean. Scientists believe it has long since frozen and expanded.
A statement from NASA described it as:
“The side of Pluto’s largest moon viewed by NASA’s passing New Horizons spacecraft in July 2015 is characterized by a system of “pull apart” tectonic faults, which are expressed as ridges, scarps and valleys—the latter sometimes reaching more than 4 miles (6.5 kilometers) deep. Charon’s tectonic landscape shows that, somehow, the moon expanded in its past, and – like Bruce Banner tearing his shirt as he becomes the Incredible Hulk – Charon’s surface fractured as it stretched.”
At half the size of Pluto, Charon is an enchanting piece of rock. As it orbits Pluto, it is closer to the host than any other satellite seen in our solar system. It’s almost another dwarf planet itself — more like two binary planets orbiting each other than a typical planet and moon relationship.
The tectonic landscape of the moon indicates there has been some expansion and swelling, resulting in the cracks. Charon also has very long canyon systems that are four times as long and deep as the Grand Canyon, according to the report.
The outer layer of Charon is primarily water ice. Scientists believe Charon could have been warm enough to cause the water ice to melt deep down, creating a subsurface ocean. But as Charon cooled over time, this ocean might have frozen and expanded (as happens when water freezes), lifting the outermost layers of the moon and producing the massive chasms we see today.
A subsurface ocean would put it in the company of other moons in our solar system, like Europa, Enceladus, and Ganymede.