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Safe and Fuel-Efficient Motion Planning for Lunar Propulsive Drones

Safe and Fuel-Efficient Motion Planning for Lunar Propulsive Drones

Elena Wittemyer, Graco Gao · N/A · 2026

vision planning control
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Summary

Propulsive drones are a promising new technology for generating high-resolution terrain models of the Moon. In future lunar missions, propulsive drones will complete a series of hops across the lunar surface while capturing images with downward-facing cameras.

Abstract Summary

Propulsive drones are a promising new technology for generating high-resolution terrain models of the Moon. In future lunar missions, propulsive drones will complete a series of hops across the lunar surface while capturing images with downward-facing cameras. We present an autonomous motion planning framework that uses a vision-guided optimal control strategy for performing safe, efficient hops between specified waypoints. The drone plans parabolic hops between waypoints generated by a global-level planner; if a nominal waypoint is unsafe or unreachable, the drone then completes a diversion maneuver to safely land. To evaluate the validity of potential landing sites, we develop a custom semantic segmentation model for identifying obstacles from aerial images, and we introduce an approach for rapidly calculating reachable terrain. We then use model predictive control (MPC) to robustly track hop trajectories that guide the drone towards safe landing sites. We test the optimal hop planner in a high-fidelity lunar simulation environment. Our results demonstrate that our unified motion planning framework yields safe, fuel-efficient hop trajectories which can be tracked rapidly and with low error via MPC.

Key Points

  • Propulsive drones are a promising new technology for generating high-resolution terrain models of the Moon.
  • In future lunar missions, propulsive drones will complete a series of hops across the lunar surface while capturing images with downward-facing cameras.
  • We present an autonomous motion planning framework that uses a vision-guided optimal control strategy for performing safe, efficient hops between specified waypoints.
  • The drone plans parabolic hops between waypoints generated by a global-level planner; if a nominal waypoint is unsafe or unreachable, the drone then completes a diversion maneuver to safely land.
  • To evaluate the validity of potential landing sites, we develop a custom semantic segmentation model for identifying obstacles from aerial images, and we introduce an approach for rapidly calculating reachable terrain.

Methods

The upcoming MoonFall propulsive drones will have a diameter of about 2.1 m, a height of about 1.2 m, and a weight of about 250 kg [ 1 ] . We use these specifications as a starting point for our simulated drone. Our drone model consists of four cylindrical thrusters attached perpendicular to the base of a rectangular prism body, as shown in Fig. 2 .

Methods — Safe and Fuel-Efficient Motion Planning for Lunar Propulsive Drones
Fig. 1: The drone hops between global waypoints. In-flight, when the drone can see its next waypoint, it identifies unsafe obstacles near the waypoint using semantic segmentation. It also calculates the reachable set of landing sites from a starting point a few seconds in the future along the tracked launch trajectory. The nominal landing site is unsafe, so the drone starts calculating the optimal descent trajectory to the nearest safe and reachable landing site. A few seconds in the future, when the descent trajectory is calculated, the drone diverts to its new landing site. Closer to the ground, it checks for smaller obstacles that the semantic segmentation model may have missed from its high vantage point. It identifies a rock at its new landing site and adjusts the remaining descent trajectory to divert to a safe final landing position.

Results

First, we report on the performance of our segmentation architecture. For our application, falsely identifying rocks/craters as regolith is more dangerous than falsely identifying regolith as rocks/craters, as we would rather unnecessarily avoid some terrain region than confidently land on an obstacle.

Moreover, for the purpose of picking a safe landing site, falsely identifying a rock as a crater or vice versa is harmless.

Results — Safe and Fuel-Efficient Motion Planning for Lunar Propulsive Drones
Fig. 2: A model of a simplified propulsive drone. Forces are applied at each of the drone’s four thrusters and are parallel to the drone’s body-centered $z$-axis.

Sources and Demonstrations

Figures are reproduced from Wittemyer et al. See the full paper for experimental details and the project page, when the paper links one, for demonstrations and videos.

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