BOULDER - A study by a Boulder scientist and his colleagues casts doubt on the idea that an Old Faithful-like water plume that shoots hundreds of miles above Saturn's tiny moon Enceladus erupts from a subsurface pool that may harbor microbial life.

After NASA's Cassini spacecraft spotted the geyser-like plume last year, some mission scientists suggested that its source is a reservoir of liquid water as little as 23 feet beneath a relatively warm spot on Enceladus' south pole.

Since liquid water is required by all known forms of life, the so-called Cold Faithful model for the Enceladus plume suggested a potential habitat for microbial life.

But in today's edition of the journal Science, John Spencer, of the Southwest Research Institute, and his Illinois and California colleagues throw a dry blanket on the watery scenario.

They argue that the Enceladus plume can form without a drop of subsurface liquid water.

Instead, the source could be ice crystals that trap gas molecules inside their cage-like structure.

Under their proposed Frigid Faithful model, the cagey crystals, called clathrates, erupt through cracks in the 300-mile-wide moon's icy outer shell, releasing the ice particles, water vapor and gases observed by Cassini.

No liquid water required.