A Mixed-Integer Extension for ESA’s Cassini1 Space Mission Benchmark

This contribution introduces a mixed-integer extension to the well-known Cassini1 space mission benchmark published by the European Space Agency (ESA). Due to it's highly nonlinear function properties, the Cassini1 benchmark is widely recognized by the evolutionary computing community as interesting test case. The Cassini1 benchmark implements a simplified model of an interplanetary space trajectory from Earth to Saturn, using four gravity-assist maneuvers (also known as fly-by's) at planets: Mercury, Mercury, Earth and Jupiter. Here the original continuous formulation of the Cassini1 benchmark is extended by four discrete (integer) variables, representing the choice of fly-by planets. Comprehensive numerical results investigate the complexity of this mixed-integer formulation and compare it with the purely continuous formulation. The results show that the difficulty to solve the mixed-integer formulation can significantly vary depending on small modifications of the integer search space. Preliminary multi-objective results are additionally presented in order to deepen the understanding of the observed mixed-integer performance.