Speaker
Description
Orbital associations of Near-Earth Objects (NEOs) can be used to identify groups with similar low-thrust mission accessibility. We present a computational pipeline that links the search for orbital associations with preliminary multi-target mission design. Candidate NEO pairs are first identified using a $k$-nearest-neighbour search based on a KD-tree and then evaluated using the Drummond $D_D$ criterion. Groups of similar orbits are then extracted using an all-pairs similarity check. An orbital-phasing indicator is used to screen these groups and identify transfer opportunities and target sequences.
The selected sequences are first screened using impulsive Lambert transfers. Promising candidates are then analysed using a bounded-acceleration low-thrust propagation model. The main accessibility metrics are mission duration and post-Earth-escape $\Delta V$. Orbital-similarity screening reduces the number of combinations considered in the trajectory search. Even for similar orbits, the required $\Delta V$ can vary considerably with orbital phasing, encounter epochs, and the chosen control parameters.
This helps show which NEO associations are also promising from a mission-design point of view. These groups can then be selected for more detailed trajectory optimisation. The pipeline is currently used for trajectory screening rather than final mission design. Target-body ephemerides are taken from JPL Horizons where available. The trajectories are propagated with adaptive step-size control using DOP853 and are also checked numerically.