Fire and Ice: Probing Jupiter's Most Interesting Moon

Of all NASA's upcoming missions, the planned exploration of the Jovian satellite Europa is perhaps the most anticipated. The sixth largest moon in the solar system, Europa resembles a vast skating rink, blanketed by a crust of frozen water nearly 3 miles deep. In 1996, the Galileo orbiter -- launched in 1989 to conduct an extensive study of Jupiter and its moons -- returned startling data: Europa may have a life-sustaining liquid ocean beneath its frosty exterior. But Europa is too far from the sun to cap ture enough solar warmth to sustain a liquid ocean. What could be the source of Europa's heat? One possible answer is that the moon's interior is constantly being ripped apart by Jupiter's immense gravitational tug. The warmth generated by that tidal fric tion may be sufficient enough to soften or even liquify some portion of Europa's icy mantle.

This theory has sent scientists' imaginations soaring: if there is a liquid ocean on Europa, could the planet be home to primitive forms of life? The concept isn't that outlandish, considering that recent studies on Earth have demonstrated that primiti ve and resilient species can thrive in inhospitable places like volcanic hydrothermal sites deep in ocean trenches. But until we can get there, we will never know for sure if Europa has a liquid subsurface or any forms of life. To unlock the moon's myster ies, Galileo will conduct several additional fly-bys over the next two years. NASA may also launch a probe to melt through the moon's icy crust in an effort to detect signs of liquid water and life. Another project, dubbed "Fire and Ice," proposes to boun ce radio waves through Europa's icy crust to see what lies beneath. With the exception of the Galileo fly-bys, these ambitious missions are likely to take place early in the next century -- which after all is only two years away. And who knows? If Europa turns out to be a haven for life, humans could one day tap its resou rces and possibly inhabit its surface. As science fiction has already taught us, anything is possible. --Taran Provost