The icy moon Europa is perhaps the most tantalizing destination in our solar system. Scientists have been trying for years to kickstart a mission to Jupiter’s most enigmatic moon, with very Earth-like concerns over costs keeping missions grounded until now. The European Space Agency’s ambitious mission to Jupiter, JUICE, will visit its fire-and-ice moons—volcanic Io, icy Europa, giant Ganymede, and cratered Callisto—in the 2030s. But it will only provide a glimpse of Europa’s surface from a couple of close flybys. With the announcement of the NASA-led Europa Clipper mission, now it looks like a much closer inspection of Europa is on the cards. It’s hard to overstate the excitement among planetary scientists, after so many years of waiting in the wings while all eyes were on Mars. This is truly a quest to understand what makes a world habitable. A watery world Europa is the smallest and smoothest of the four Galilean moons. At 1,940 miles across, it is roughly a quarter of the size of Earth, composed of a mixture of ices and rocks. When the Galileo spacecraft flew over Europa in the 1990s, it uncovered evidence of a global sub-surface ocean: vast, deep, dark waters hidden beneath the ice crust. The water doesn’t freeze completely because it’s constantly kneaded by powerful tidal forces as the moon orbits around Jupiter once every 3.5 days. What’s more, the ocean is believed to be in direct contact with the surface ices and the moon’s silicate mantle, which brings together all the necessary ingredients for a habitable environment: liquid water, a source of energy, and a source of minerals/nutrients. We know that life on Earth can exist in even the most extreme environmental conditions (for example, bacteria known as extremophiles), so maybe—just maybe—Europa’s hidden ocean could support life. More via Quartz.
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