Europa Clipper Mission Analysis: Design of the 21F31 Reference Trajectory

Europa has been a prime target for space exploration ever since 1997, when the Galileo spacecraft magnetic measurements of Europa suggested the moon might hide a vast, salty ocean beneath its icy surface. To investigate its habitability, NASA developed Europa Clipper, which will be launched in October 2024 on a Falcon Heavy rocket from Cape Canaveral. After a 5.5-year interplanetary journey that includes one Mars gravity assist and one Earth gravity assist, Europa Clipper will reach Jupiter in April 2030 and insert into a 200-day orbit in the Jovian system. Subsequently, a complex gravity assist trajectory (tour) will commence. This paper will present the reference tour, 21F31, which is comprised of 53 flybys of Europa, 9 flybys of Callisto, 7 flybys of Ganymede and culminates with Ganymede impact to meet planetary protection requirements. The principles, design process, and evolution of tour designs—which leverage on more than two decades of research in astrodynamics and multiple interactions with planetary scientists and engineers—as well as the science objectives and mission constraints that drive the design of the tour will be covered in this paper. This paper is part of a series of papers describing the mission design and navigation analysis of Europa Clipper, which have been presented at different international conferences.