麻豆传媒

IN GREEK mythology, Enceladus was a giant who was defeated in battle by Athena and buried under Mount Etna. When the giant hisses, Mount Etna erupts.

A billion and a half kilometres from the sun, Saturn鈥檚 moon Enceladus is a tiny world of ice. Yet, like its namesake, it has an explosive personality, and it is now the hottest property in astrobiology. New findings suggest that the geysers spewing from the moon鈥檚 south polar area are signs of a watery layer perhaps a few tens of metres below the surface (see 鈥淪aturn鈥檚 miniature moon a possible haven for life鈥�). If so, this is the most accessible liquid water in our solar system, short of Earth鈥檚 oceans.

Up to now, the place astrobiologists most wanted to explore was Europa 鈥� a much larger moon of Jupiter that appears to have an ocean of water beneath its crust. But that water is under kilometres of ice. So Enceladus now looks like a much better bet. It is twice as far away, but the water is easier to reach. It may be our best chance to explore a habitable zone beyond Earth. NASA recently suspended a mission to Europa for budgetary reasons. When that money is available, it may be better spent on a very different destination.