# Generating Planar Trajectories for Neptunian System Exploration Using Motion Primitives

## TL;DR

This paper presents a method for generating spacecraft trajectories in the Neptunian system using motion primitives and graph-based path planning.

## Contribution

The novelty lies in applying motion primitives and constrained path search to design diverse spacecraft trajectories in the Neptune-Triton system.

## Key findings

- Motion primitives derived from periodic orbits and manifolds enable automated trajectory generation.
- The approach successfully designs high-energy and low-energy trajectories in the Neptunian system.
- Optimized trajectories with impulsive maneuvers are generated for science orbit insertion and transfers.

## Abstract

This paper uses a motion primitive approach to automatically generate constrained spacecraft trajectories for Neptunian system exploration. Motion primitives are generated as smaller building blocks of motion that summarize periodic orbits and arcs along stable and unstable manifolds of selected orbits in the Neptune-Triton circular restricted three-body problem. The sequential composability of these motion primitives is represented by a graph that also incorporates path and maneuver constraints. This graph is searched using a k-best paths algorithm to generate multiple motion primitive sequences. These sequences are transformed into an array of geometrically diverse initial guesses. After corrections and optimization, the resulting tradespace of continuous, constrained trajectories with impulsive maneuvers is analyzed. This approach is applied to two planar trajectory design scenarios in the Neptunian system: high-energy insertion into a Neptune-centered science orbit after interplanetary arrival and low-energy transfers between science orbits centered around each of Neptune and Triton.

The online version contains supplementary material available at 10.1007/s40295-025-00545-z.