NASA's Cassini spacecraft recently completed a 26-hour gravity observation of Saturn's moon Enceladus, sending back data scientists will use to understand the moon's interior composition and structure. The flyby took Cassini through the water-rich plume flaring out from Enceladus' south polar region, with a closest approach of about 100 kilometers (60 miles).
A steady radio link to NASA's Deep Space Network on Earth enabled Cassini's scientists to use the radio science instrument to measure the variations in the gravitational pull of Enceladus. Analyzing the wiggles will help scientists understand whether an ocean, pond or great lake lies under the famous "tiger stripe" fractures that spew water vapour and organic particles from the south polar region.
Results from the experiment will also tell scientists if bubbles of warmer ice in the interior rise toward that region's surface like an underground lava lamp.