The New Horizons spacecraft headed to Pluto will explore Charon, one of the moons in the system, in search of evidence of an ancient underground ocean. 

Orbiting 29 times further away from the sun than does the Earth, temperatures on these worlds are around 380 degrees below zero Fahrenheit. This is far too cold for liquid water to exist on the surface. 

Saturn's moon Enceladus has an icy surface, covered in cracks. Astronomers believe that if Charon, the largest of Pluto's moons shows similar features, there may have once been liquid oceans underneath. 

A new NASA study found a new way to determine subsurface composition from the patterns of cracks in ice. This information could reveal if Charon once had an underground ocean. 

"By comparing the actual New Horizons observations of Charon to the various predictions, we can see what fits best and discover if Charon could have had a subsurface ocean in its past, driven by high eccentricity," Alyssa Rhoden of NASA's Goddard Space Flight Center said.  

New Horizons launched to the icy body in January 2006, just seven months before it was demoted to "dwarf planet" status. Now, mission planners intend to use the spacecraft to study the frozen surface, looking for evidence of past subterranean seas. 

Europa, one of dozens of satellites orbiting Jupiter, and Enceladus, moving around Saturn, are each pulled back-and-forth in their orbits by a myriad of other moons. This tug-of-war prevents the moons from settling into a calm orbit. Instead, this action constantly warps the moons, creating internal heating. This warmth may have been  enough to keep oceans in liquid form for long periods of time. A similar action could also allowed the satellite to hold on an ocean of liquid water, the study asserts. 

Pluto and Charon will be visited by the spacecraft in July 2015. This will be the most in-depth, and close-up, study ever performed on the pair. There are five known moons in Pluto's system. Charon possesses one-eighth the mass of its host world. This is a record for the solar system, and the pair is often considered to be a double-planet system.

Astrophysicists believe the conglomeration of tiny worlds was created during a collision between a planet and dwarf planet billions of years ago. Astronomers believe it formed much closer to Pluto than it is today, after coalescing from debris left over from the impact. 

Charon, nearly half the diameter of its companion, was discovered in 1978. Images taken of Charon by astronomers indicate the satellite is most likely locked to Pluto by tidal forces. Just like our own moon, one face of the body would face eternally toward its planetary companion. If this is true, the surface would be largely free of cracks, and any ocean that once existed would be frozen. 

Study of patterns in planetary ice and what they can tell us about possible subterranean oceans was profiled in the online open-source journal Icarus.