NASA scientists have found evidence that suggests that Charon, Pluto’s largest moon, may have had once a subterranean ocean.

Scientists analyzed data collected by the New Horizons mission, showed that this ocean apparently burst through the surface and froze to become ice.

The New Horizons mission transmitted a series of images that showed fractures on the surface of the moon which are believed to be the result of ridges, scarps and valleys that eventually froze and expanded, causing the moon’s surface to fracture and stretch.

A close-up of the canyons on Charon, Pluto's big moon, taken by New Horizons during its close approach to the Pluto system last July. Multiple views taken by New Horizons as it passed by Charon allow stereo measurements of topography, shown in the color-coded version of the image. The scale bar indicates relative elevation. Credit: NASA/JHUAPL/SwRI
A close-up of the canyons on Charon, Pluto’s big moon, taken by New Horizons during its close approach to the Pluto system last July. Multiple views taken by New Horizons as it passed by Charon allow stereo measurements of topography, shown in the color-coded version of the image. The scale bar indicates relative elevation.
Credit: NASA/JHUAPL/SwRI

Charon was first discovered in 1978 by scientists from the United States Naval Observatory. It is also called Pluto I because it is half the size of the planet, being the largest of its five moons.

The moon has a giant canyon which is as long as the Earth’s Grand Canyon and twice as deep, and it is believed to have once been the ocean. All its features might have drastically frozen due to very low temperatures.

Originally, when Charon was a young moon, the outer layer of the moon was primarily water ice, but its inside was kept warm by heat produced by the decay of radioactive elements and the remaining heat of its own formation.

According to the related article published on NASA’s website, the moon could have once been warm enough to melt down a big part of the water ice and create the subterranean ocean. However, “as Charon cooled over time, this ocean would have frozen and expanded, lifting the outermost layers of the moon and producing the massive chasms we see today”, NASA explained.

As seen in the images

Images of a region on Charon called Serenity Chasma provided evidence of the freezing and expanding process. This area is one of the longest chasms of the Solar System, which measures 1100 miles long and 4.5 miles deep.

NASA created topographical maps of the expansions that revealed a consistency between the features and the proposed geological process. Evidence showed that Charon’s water ice layer was at first partially liquid and froze with the passing of time.

Source: NASA