Echoes of Icequakes: Simple probe could measure Europa’s ocean and icy shell
By Sid Perkins
A football-size space probe could provide a low-cost way to determine whether there’s a liquid ocean on the Jovian moon Europa. The ice-sheathed, nearly airless world is just a bit smaller than our own moon, and it stands as one of the solar system’s prime candidates for hosting life beyond Earth. Discussions among scientists about small, discount probes to be sent to Europa have intensified since funds earmarked for a full-scale orbiter were dropped from the President’s 2003 budget proposal.
The probe would act as an electronic ear, detecting sound waves traveling through Europa’s icy crust, says Nicholas C. Makris, an acoustical oceanographer at the Massachusetts Institute of Technology. Those reverberations could be generated by a variety of sources, including the occasional impacts of objects falling from space. However, Makris contends that if there is a liquid ocean within Europa’s thick shell of ice, its tidal motions could provide a nearly continuous source of seismic shivers.