3.4.1 Exploring icy worlds
In the late 1970s, NASA’s Voyager mission [Tip: hold Ctrl and click a link to open it in a new tab. (Hide tip)] provided the first tantalising clues that Europa, one of Jupiter’s moons, might have an ocean beneath its thick icy shell. Since then, missions such as NASA’s Galileo and Cassini-Huygens spacecraft have provided evidence of sub-surface oceans on other moons of Jupiter and Saturn, such as Ganymede, Callisto, Titan and Enceladus (Figure 21).
With the identification of water comes the possibility of life, and much effort has been put into understanding whether these subsurface environments could be habitable. Excitingly, several missions are planned to visit these bodies in the coming years: Europa Clipper, to explore Europa in more detail from orbit; JUICE (JUpiter ICy Moons Explorer), to study the icy moons Ganymede, Europa and Callisto; and Dragonfly, focusing on the surface of Saturn’s moon Titan.
These missions present exciting opportunities to learn more about icy worlds, their potential habitability, role in pre-biotic chemistry and physical and chemical conditions that result in the presence of water and energy that might support life. However, there is only so much that a single space mission can accomplish, especially since Europa Clipper and JUICE are orbiters. So, it is likely that these moons will be targets for other missions in the future. It is therefore critical to ensure these moons remain unspoilt and pristine to not jeopardise future investigations. More importantly, if these moons were to harbour life, it is imperative that we do not interfere or disrupt their habitat in any way.