The number of spacecraft flying in highly nonlinear gravitational fields is largely increased during the last few decades, and probes orbiting in Lissajous or Halo orbits can be found around both the Lagrangian Points L1 and L2 of the Sun-Earth&Moon system.
Recently, another point in space has become more and more appealing, i.e. the Sun-Earth Saddle Point (SP). The increasing interest towards the exploration of this particular region within the Solar System is due to the fact that it represents a suitable location to measure possible deviations from the General Relativity and find scientific evidence for the correctness of other theories, such as the MOND/TeVeS.
The particular location as well as its non-equilibrium nature suggest that SP can be more easily reached by using highly nonlinear orbits, as opportunistic mission extension of spacecraft already about the Lagrangian points. Nonetheless, this introduces some concerns about the applicability in a real scenario, due to the high sensitivity and the limited control authority of these missions. For this reason, a validation analysis is mandatory to assess the feasibility of flying such orbits with a special focus on their navigability.