From 1995 to 2003, NASA's Galileo spacecraft made several circles around Jupiter's moon Europa. Several results from moon observations have indicated the existence of a liquid ocean beneath Europa's icy surface. The ocean, the researchers believe, can harbor microbial life, or hold evidence of extinction. Although scientists have generally agreed on where to look for life - under a thick ice shell, where water comes in contact with the rocky core, and where biochemical ingredients for life may exist.
But scientists still argue about how to get there to collect samples.
Tunnel Robot
“Estimates for the thickness of the ice shell range from 2 to 30 kilometers and are a major barrier that any lander will have to overcome to gain access to areas that we believe may contain biosignatures characteristic of life in Europe,” says Andrew Dombard, assistant professor of earth and environmental sciences at the University of Illinois at Chicago.
Dombard and his colleagues presented a possible solution to this problem at the American Geophysical Union meeting in Washington, DC this week: a nuclear tunnel probe.
Dombard and his wife, D'Arcy Meyer-Dombard, are part of a group of scientists from the COMPASS research group at the Research Center. Glenn at NASA, a multidisciplinary group of scientists and engineers dedicated to developing technologies and solutions for space exploration and scientific missions.
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Scientists have conducted a conceptual study of a nuclear powered "tunnel robot" that can penetrate the ice shell and reach the top of Europa's ocean, while carrying devices and tools that can be used to look for signs of existing or extinct life. The robot will also appreciate the habitability of the ice shelf itself.
“We didn't think about how the tunnel bot would get to Europa or turn around in the ice,” Dombard says. “We just assumed he could get there and focused on how he would perform during his descent to the ocean.”
The bot will have to collect ice samples across the entire shell, as well as water at the ice-water interface, and look at the bottom of the ice in search of microbial biofilms. The robot will also be able to search for liquid water "lakes" in the ice shell.
Scientists considered two designs for their bot: one powered by a small nuclear reactor, and the other with General Purpose Heat Source bricks, radioactive heat source modules designed for space missions. Heat from both of these sources can be used to melt the ice shell. Communication will be provided by a chain of "repeaters" connected to the bot by fiber optic cables.
NASA regularly sponsors concept studies to check where the technology is in the future to help us find answers to important questions in the solar system. Perhaps there is no more important question than “does life exist elsewhere?” And Europe is one of the best places to look. If a tunnel mission is planned, which of the two projects will be chosen remains to be seen.
Ilya Khel
