Exploring the Jupiter System through unique joint JUICE and Europa Clipper observations

Launched in April, 2023, ESA’s JUpiter ICy moons Explorer (JUICE) is now two years into its journey to the Jupiter system. Upon arrival in 2031, the spacecraft will orbit Jupiter for 3.5 years, making 35 total encounters with Ganymede, Europa, and Callisto, before going into orbit about Ganymede for 1 year.  NASA’s Europa Clipper successfully launched in October 2024, and arrives in the Jupiter system in 2030, more than a year before JUICE. Orbiting Jupiter, the Clipper spacecraft will spend a year in the system before focusing on ~52 flybys of Europa during a nominal three-year primary mission phase, while also making multiple serendipitous flybys of Ganymede and Callisto.A preliminary analysis of potential joint science opportunities has been conducted by a small team of scientists from the JUICE and Clipper mission teams. Ideas have been collated from JCSC members as well as from three joint Clipper-JUICE workshops (2018, 2019, 2022), and the Science Traceability Matrix from a prior joint ESA-NASA study, the Europa Jupiter System Mission (EJSM). We have produced two reports on science that can be accomplished during the two spacecrafts’ cruise and Jupiter approach phases, and potential opportunities once JUICE and Clipper are both in orbit around Jupiter. For the former, we note that cruise represents a rare occasion for joint measurements of interplanetary space between the orbits of Mars and Jupiter, and an unprecedented opportunity for an upstream solar wind monitor (JUICE) during approach to the Jupiter system once Clipper is already orbiting Jupiter.  For the latter, we find that the presence of two flagship-class, well-instrumented spacecraft in the Jovian system during the same 4.3 year period affords extraordinary opportunities to increase the science return beyond that possible from each mission alone. Joint observations are possible of all four Galilean satellites, the Jovian rings and small satellites, Jupiter’s atmosphere, and the magnetosphere. 100 potential joint science objectives have been identified, of which 50 are considered high priority. These include many synergistic measurements; some which would take place contemporaneously, and some measurements that are coordinated but asynchronous; and many complementary objectives such as cross-calibration of instruments and also serendipitous opportunities. The data return would be further enhanced by coordination with ground- or space-based assets during some of the measurements.There are currently no firm commitments from NASA or ESA to accomplish science beyond that of each mission’s primary science objectives. However, discussions continue and we are hopeful that our recommendations for the opportunities afforded by the two missions’ alignment will enable resource support to be found.