On icy moon Enceladus, expansion cracks let inner ocean boil out

In 2006, the Cassini spacecraft recorded geyser curtains shooting forth from “tiger stripe” fissures near the south pole of Saturn’s moon Enceladus—sometimes as much as 200 kilograms of water per second. A new study suggests how expanding ice during millennia-long cooling cycles could sometimes crack the moon’s icy shell and let its inner ocean out, providing a possible explanation for the geysers.