It may be five years away from launch, and over a decade before our Jupiter Icy Moons Explorer reaches the gas giant and its icy moons, but preparations are well under way. Ganymede and Europa are both prime suspects for life in our solar system. In March of 2015, NASA's Hubble Space Telescope revealed the best evidence yet for an underground saltwater ocean on Ganymede, Jupiter's largest moon shown above. The subterranean ocean is thought to have more water than all the water on Earth's surface. Identifying liquid water is crucial in the search for habitable worlds beyond Earth and for the search for life, as we know it. Scientists estimate the ocean is 60 miles (100 kilometers) thick -- 10 times deeper than Earth's oceans -- and is buried under a 95-mile (150-kilometer) crust of mostly ice.
The spacecraft is furnished with a laboratory of instruments that will investigate Jupiter's turbulent atmosphere and vast magnetosphere, as well as study the planet-sized moons Ganymede, Europa and Callisto. All three moons are thought to have oceans of liquid water beneath their icy crusts and should provide key clues on the potential for such moons to harbor habitable environments.
Juice's cameras will capture exquisite details of the moon's features, as well as identify the ices and minerals on their surfaces. Other instruments will sound the subsurface and interior of the moons to better understand the location and nature of their buried oceans. The tenuous atmosphere around the moons will also be explored.
The spacecraft will also include booms such as a 10 m-long magnetometer mast (seen towards the bottom of Juice in the artist impression), a 16 m radar antenna (the long boom across the top), and antennas to measure electric and magnetic fields.
Juice is scheduled for launch in 2022 on a seven-year journey to the Jovian system. Its tour will include a dedicated orbit phase of Jupiter, targeted flybys of Europa, Ganymede and Callisto, and finally nine months orbiting Ganymede – the first time any moon beyond our own has been orbited by a spacecraft.
In the artist's impression above, which is not to scale, Ganymede is shown in the foreground, Callisto to the far right, and Europa center-right. Volcanically active moon Io is also shown, at left. The moons were imaged by NASA's Galileo spacecraft; Jupiter is seen here with a vivid aurora, captured by the NASA/ESA Hubble Space Telescope.
The Daily Galaxy via European Space Agency