Pluto May Host an Ocean

* New research indicates distant Pluto might have an ocean beneath its icy shell.
* The ocean would have formed from melted ice heated by the decay of radioactive potassium.
* More information should come from NASA's New Horizons probe, which is due to fly by Pluto in 2015.

Pluto has an icy exterior, but inside, the decay of radioactive potassium may have melted an ocean of liquid. Click to enlarge this image.

Freezing, distant Pluto seems an odd place to look for oceanfront real estate, but if a new computer model is correct, the dwarf planet harbors a sizeable pool of liquids beneath its thick icy shell.

Scientists suspect Pluto holds a rocky core spiked with radioactive materials that are slowly breaking down, releasing enough heat in the process to melt ice and keep it liquid. The temperature on Pluto's surface is about -375 degrees Fahrenheit.

Considering Pluto's size and composition, just 100 parts per billion of radioactive potassium would be enough to maintain an ocean 60 to 105 miles in depth 120 miles beneath the surface, says planetary scientist Guillaume Robuchon, with the University of California at Santa Cruz.

"These simulations suggest that Pluto likely possesses an ocean at the present day," Robuchon wrote in a synopsis of his research presented last week at the American Geophysical Union conference in San Francisco.

The idea of an ocean on Pluto may not remain theoretical for long. NASA's New Horizon's space probe is more than halfway through a 10-year journey to Pluto. After traveling more than 3 billion miles, it is scheduled to fly past Pluto and its moons in July 2015.

Scientists don't know what they'll find -- no space probe has ever visited Pluto, which is about 39 times farther from the sun than Earth.

"We are going to an entirely new type of world. Everything is interesting. It's like the first mission to Mars," New Horizons lead scientist Alan Stern, with the Southwest Research Institute in Boulder, Colo., told Discovery News.

"Clearly if we see geysers like (Saturn's moon) Enceladus, it would be easy to determine that there is subsurface water venting up," Stern said. "It would be a huge discovery."

In addition to surface features, such as cracking in the ice or smooth lava-like flows, scientists will look at Pluto's poles for clues about the shape of its interior. For an ocean to exist, Pluto likely would need to have distinct layers of rock and ice.

"Pluto's shape should reflect its construction," planetary scientist Bil McKinnon, with Washington University in St. Louis, told Discovery News.

Other clues may come from telltale chemicals escaping from Pluto's atmosphere, the result of geyser-like eruptions spewing particles.

"It's certainly possible that a body the size of Pluto could have an ocean," McKinnon said.