Jupiter’s moon Europa is slightly smaller than Earth’s moon. Its surface is smooth and bright, consisting of water ice crisscrossed by long, linear fractures. Like our planet, Europa is thought to have an iron core, a rocky mantle and an ocean of salty water beneath its ice crust. Unlike Earth, however, this ocean would be deep enough to extend from the moon’s surface to the top of its rocky mantle. Being far from the sun, the ocean’s surface would be globally frozen over. While evidence for this internal ocean is quite strong, its presence awaits confirmation by a future mission.
Europa orbits Jupiter every 3.5 days and is locked by gravity to Jupiter such that the same hemisphere of the moon always faces the planet. Because Europa’s orbit is slightly stretched out from circular, or elliptical, its distance from Jupiter varies, creating tides that stretch and relax its surface. The tides occur because Jupiter’s gravity is just slightly stronger on the near side of the moon than on the far side, and the magnitude of this difference changes as Europa orbits. Flexing from the tides supplies energy to the moon’s icy shell, creating the linear fractures across its surface. If Europa’s ocean exists, the tides might also create volcanic or hydrothermal activity on the seafloor, supplying nutrients that could make the ocean suitable for living things.
NASA’s planned Europa Clipper would conduct detailed reconnaissance of Jupiter’s moon Europa and investigate whether the icy moon could harbor conditions suitable for life.
The mission would place a spacecraft in orbit around Jupiter in order to perform a detailed investigation of the giant planet’s moon Europa – a world that shows strong evidence for an ocean of liquid water beneath its icy crust and which could host conditions favorable for life. The mission would send a highly capable, radiation-tolerant spacecraft into a long, looping orbit around Jupiter to perform repeated close flybys of Europa.
NASA has selected nine science instruments for a future mission to Europa. The selected payload includes cameras and spectrometers to produce high-resolution images of Europa’s surface and determine its composition. An ice penetrating radar would determine the thickness of the moon’s icy shell and search for subsurface lakes similar to those beneath Antarctica’s ice sheet. The mission would also carry a magnetometer to measure the strength and direction of the moon’s magnetic field, which would allow scientists to determine the depth and salinity of its ocean.
Image credit: NASA / JPL / Galileo / Voyager & Processed by Kevin M. Gill