In the coming years, NASA and the European Space Agency (ESA) will send two robotic missions to explore Jupiter’s icy moon Europa. These are none other than NASA’s Europa Clipper and the ESA’s Jupiter Icy Moons Explorer (JUICE), which will launch in 2024, and 2023 (respectively). Once they arrive by the 2030s, they will study Europa’s surface with a series of flybys to determine if its interior ocean could support life. These will be the first astrobiology missions to an icy moon in the outer solar system, collectively known as «ocean worlds.»
In the coming years, NASA and the European Space Agency (ESA) will send two robotic missions to explore Jupiter’s icy moon Europa. These are none other than NASA’s Europa Clipper and the ESA’s Jupiter Icy Moons Explorer (JUICE), which will launch in 2024, and 2023 (respectively). Once they arrive by the 2030s, they will study Europa’s surface with a series of flybys to determine if its interior ocean could support life. These will be the first astrobiology missions to an icy moon in the outer solar system, collectively known as «ocean worlds.»
One of the many challenges for these missions is how to mine through the thick icy crusts and obtain samples from the interior ocean for analysis. According to a proposal by Dr. Theresa Benyo (a physicist and the principal investigator of the lattice confinement fusion project at NASA’s Glenn Research Center), a possible solution is to use a special reactor that relies on fission and fusion reactions. This proposal was selected for Phase I development by the NASA Innovative Advanced Concepts (NIAC) program.
The list of ocean worlds is long and varied, ranging from Ceres in the Main Asteroid Belt, the moons of Jupiter (Callisto, Ganymede, and Europa), Saturn (Titan, Enceladus, and Dione), Neptune’s largest moon (Triton), and Pluto and other bodies in the Kuiper Belt. These worlds are all believed to have interior oceans heated by tidal flexing due to gravitational interaction with their parent body or (in the case of Ceres and Pluto) the decay of radioactive elements. Further evidence of these oceans and activity includes surface plumes and striated features indicating exchanges between the surface and interior.
The main challenge for exploring the interiors of these worlds is the thickness of their ice sheets, which can be up to 40 km (25 mi) deep. In Europa’s case, different models have yielded estimates of between 15 and 25 km (10 and 15 mi). In addition, the proposed probe will need to contend with hydrostatic ice with varying compositions (such as ammonia and silicate rock) at different depths, pressures, temperatures, and densities.
