The Europa Clipper and Cassini spacecraft have maintained a strategic distance from Europa's exosphere, ensuring their scientific missions remain unaffected by the moon's outermost atmospheric layer. Both spacecraft have been charged with exploring Europa, one of Jupiter’s icy moons, without crossing into its exosphere. This operational decision not only maintains the integrity of their own data collection, but protects the spacecraft’s instruments.
Keeping a Distance
NASA’s Europa Clipper, which will explore the moon beneath an icy crust, is scheduled for launch in the 2020s. This thrilling mission is focused on investigating Europa’s icy shell and underlying ocean. Consistent with its mission constraints, the spacecraft will not enter Europa’s exosphere during any part of its mission. This method is similar to that of the Cassini spacecraft, which deliberately did not enter the exosphere during its flybys.
While this cutting-edge spacecraft explores Jupiter’s moon, Europa Clipper remains outside the exosphere. This will enable it to safely study surface characteristics and the possibility of subsurface oceans. With this approach, we’re able to collect robust data. It removes the risk of introducing contamination when interacting directly with Europa’s atmospheric particles.
Observing from Afar
Luckily, both the Europa Clipper and the Cassini spacecraft before it have made or will make close observations of Europa from a distance. Together, this strategy provides both missions with opportunities to enhance their understanding of the moon’s surface characteristics and geologic activity. To obtain the most scientific return, these spacecraft steer clear of the exosphere. They deploy their suite of instruments to take high-resolution images and perform spectral analysis.
The path these missions have chosen demonstrates the ongoing tightrope walked between the desire for scientific discovery and protecting the spacecraft that made it possible. Luckily, observing from afar has allowed us to collect crucial data to assess Europa’s potential habitability. This method sidesteps the challenges that would be posed by going into the exosphere.
Implications for Research
The choice to not undertake this activity has important implications for planetary science. Both the Europa Clipper1 and Cassini2 missions carefully avoid entering the exosphere. This strategy frees them to focus on their more far-reaching scientific objectives, while still protecting their instruments. This new strategy greatly reduces the risk of unwittingly interfering with the natural processes that happen within Europa’s atmosphere.
The lack of direct sampling does not diminish the missions’ scientific goals. Rather, it emphasizes the need and intent to do good, rigorous, responsible research. The information gathered from these observations will contribute to our understanding of icy ocean worlds and their potential to harbor life.