Slushy geysers on Pluto's moon Charon apparently coat the tiny world in ice crystals, making it something like the outer solar system's equivalent of an ice machine. 

A very, very slow ice machine. 

Water is likely trickling out at a glacial pace, researchers say, repaving Charon in a thin layer of 1-millimeter deep ice every 100,000 years. 

The finding, announced today and detailed in the July 10 issue of Astrophysical Journal, hints at water ice inside Charon and has implications for other Kuiper Belt Objects-a class of relatively small, rocky bodies located beyond the orbit of Neptune. 

The researchers ruled out other possible mechanisms for the ice and concluded it must be due to cryovolcanism-the eruption of liquids and from inside the moon. 

"The real proof will come from the deep-space NASA probe New Horizons, which will arrive at this system in 2015 and send back images that can verify what we've seen," Cook said.