Persistent Detection Corridor (PDC)

Definition

The Persistent Detection Corridor (PDC) is a concept proposed by Klonowski et al. (2025). It refers to the spatial volume within which a spacecraft can continuously fly without exceeding the detection capability of a given SSA architecture. The PDC guarantees that high-value assets (such as crewed spacecraft) remain within the architecture's detectable region even under small perturbations, providing a predictable safety corridor for crewed cislunar space missions.

Generation Method

The generation of a PDC involves the following steps:

1. Graph Representation

The architecture's time-evolving detectable regions are encoded as a graph structure:

• Nodes: Centroids of detectable regions
• Edges: Connectivity between adjacent detectable regions
• Edge Weights: Control cost for traversing adjacent regions

2. Path Search

An A* algorithm is used to search for persistently detectable paths within the detection graph:

where $c_e$ is the traversal cost of edge $e$, and $\mathcal{P}$ is the set of edges along the path.

3. Trajectory Optimization

Trajectory refinement is performed on the searched path using a collocation method (such as Hermite-Simpson):

• Generate dynamically feasible trajectories that satisfy the dynamics constraints
• Minimize the control cost $\Delta v$

Core Elements

Mathematical Definition

The PDC is a spatial volume $\mathcal{C}$ satisfying the following condition: for any reference trajectory $\mathbf{x}(t) \in \mathcal{C}$, there exists a detection threshold $\lambda$ such that $\|\mathbf{x}(t) - \mathcal{D}(t)\| \leq \lambda$, where $\mathcal{D}(t)$ is the architecture's detectable region at time $t$.

Key Properties

• The PDC guarantees that a spacecraft at any position within the corridor can be detected by the architecture
• Corridor width is related to the allowable perturbation magnitude
• The PDC can be used for trajectory optimization and mission planning

Application Scenarios

The PDC is applicable to cislunar crewed mission planning, ensuring that astronauts remain within the detection range of ground stations or backup observation systems in emergency situations.

Related Concepts

• Cislunar Space Situational Awareness Architecture
• A* Search Algorithm
• Direct Collocation

References

• Klonowski M, Heidrich C, Owens-Fahrner N, et al. Persistent Detection Corridors for Crewed Missions and Cislunar Space Situational Awareness[J]. The Journal of Spacecraft and Rockets, 2025.
• Klonowski M. Cislunar Space Situational Awareness Architecture Design and Analysis[D]. University of Colorado Boulder, 2025.