Here's a winter ski resort you probably haven't thought of: Enceladus, a moon circling Saturn, which, in addition to ice-spewing volcanoes, has a constant snowfall of fine, powdery crystals.
"The color is very pale pinky, I think," lead researcher Paul Schenk, with the Lunar and Planetary Institute in Houston, told Discovery News. "It is believed to be a salty water ice snow and that might give it a slight tint."
Using data collected by NASA’s Saturn-orbiting Cassini probe, Schenk's team built computer models and found that icy particles blasting out from the moon’s hot surface vents, known as "tiger stripes," return in regular, predictable patterns.
The crystals are very tiny -- only a fraction of a millimeter in length and about a micron or two in diameter. A micron is about the width of a red blood cell. But the icy snowfall, finer than talcum powder, builds up steadily over time, accumulating in drifts that vary from a few millimeters in height to more than 300 feet.
"I think most people though maybe some plume dust could fall on Enceladus but without the models, the color mapping and the high-res images (from Cassini) I don't think anyone really understood where it would go or if it would have any real thickness," Schenk said.
While snow falls on Enceladus' surface, evidence mounts for an underground ocean swirling beneath the moon's frozen crust, another team of researchers, also using Cassini data, suggest in a related report.
Analysis of the fracture patterns in the ice surrounding the moon’s southern pole matches what would created by a floating shell of icy on top of a global liquid ocean, reports geologist Simon Kattenhorn and colleagues at the University of Idaho.
"This finding increase to at least three the number of outer planet satellites likely to possess a subsurface liquid water layer," the researchers write in the Sept. 22 edition of Geophysical Research Letters.
The ice fracture patterns are the latest in a growing body of evidence that Enceladus has an underground ocean. Researchers previously found salts in the icy plumes blasting off the moon’s surface. Salts typically are remnants of rock diluted in water. Also, the force with which the plumes blast particles into space can best be explained by water.
"A year ago, we weren't completely sure that there was liquid water underneath the surface of Enceladus that was causing the plumes," astronomer Bonnie Buratti, with NASA's Jet Propulsion Laboratory in Pasadena, Calif., told Discovery News. "Now there are a number of lines of evidence."
Schenk presented his research at a planetary sciences conference under way in France this week.