David M. Karl would like to know if there's life on Jupiter's frozen moon Europa. He'd also like to know if there's life in Antarctica's ice-covered Lake Vostok. And he thinks that studying the second question is good preparation for tackling the first.

"You can go there many times," he says of Lake Vostok. "There's room for failure." By contrast, he notes, on Europa, "you want to do it right the first time."

Karl, a University of Hawaii oceanographer, co-edited a report on Lake Vostok that was just released by the National Science Foundation (NSF). The report, based on a conference held last November, calls for further scientific study of the lake -- which, similar to the oceans believed to exist on Europa, is buried beneath thick layers of ice.

Lake Vostok, about the size of Lake Ontario, is the largest known of Antarctica's many ice-covered lakes. As part of a joint U.S.-French-Russian project, scientific teams have drilled as far as 3,623 meters (11,880 feet) into the ice, stopping short of the lake itself to prevent possible contamination.

Viable microorganisms have been found throughout much of the ice core. Such microorganisms would fall into the category of extremophiles -- microscopic organisms that thrive in extreme environments. Microbes that are able to live under extreme pressures or at superheated or sub-zero temperatures, or that can stay alive in some sort of dormant stage for thousands of years could yield clues to where analagous extraterrestrial life forms might be found.

However, it remains unclear whether the lake itself contains life. Future drilling operations, taking safeguards to avoid contaminating the lake, may resolve this question. And such experience, says Karl, will prove invaluable in designing future missions to Europa -- providing lessons in how to drill through ice, sample liquids, and search for possible life on the Jovian moon.