Three-Dimensional Resonant Hopping Strategies and and the Jupiter Magnetospheric Orbiter

S INCE Mariner 10’s first swingby at Venus in 1974, gravity assists have been used successfully in many missions. The missionsGalileo andCassini, and the planned Jupiter EuropaOrbiter (NASA) and Jupiter Ganymede Orbiter (ESA), implement several gravity assists connecting resonant orbits to reduce the spacecraft energy. The missions Ulysses and Cassini, and the planned Solar Orbiter (SOLO) (ESA) and Solar-C [Japan Aerospace Exploration Agency (JAXA)], use gravity assists to increase the inclination. JAXA’s planned Jupiter Magnetospheric Orbiter (JMO) is an example of amission exploring amoon system at high latitudes. JMO requires 10s of gravity assists to both reduce the apocenter and increase the inclination. Each gravity assist connects two resonant orbits, so that the entire sequence is an example of resonant hopping. The solution space of such problems is very large, andmethods are needed to explore it quickly during preliminary design. This Note studies the three-dimensional (3-D)-resonant hopping strategy in general, and it presents an automated trajectory design method. The first part of this work shows that the Tisserand constant is the main problem parameter, and it introduces the 3-D-Tisserand graph, which gives insight to the problem. Somenewanalytical formulas are used to compute fixed-altitude gravity assists connecting resonant orbits. The graph and the formulas are the first main results of the Note. The second part of this work implements the formulas in a branchand-bound algorithm. The algorithm is applied to the JMO mission design, providing almost 10,000 solutions in just a fewminutes. The algorithm and the solution space are the second main results of this work. Details are given for one particular solution that reaches 48 inclination on the Jovian equator in less than 1.5 years.