Autonomous inspection of resident space objects is essential for space situational awareness and is an important tool for executing proximity operations in constrained orbital environments. Inspection is necessary for missions such as debris removal, satellite repair, and in-orbit assembly and manufacturing. Recent missions include the Remora mission conducted by Starfish Space and Impulse Space, the Qingzhou prototype spacecraft, and Astroscale’s ADRAS-J, a demonstration satellite that successfully captured close-range pictures of space debris.
Related Work
Inspection planners comprise two coupled components: a guidance system that determines the viewpoints to visit, and a metric that quantifies whether points of interest (POIs) are considered inspected from those viewpoints.
The metric informs viewpoint selection, and guidance executes it. Together, they support the goal of achieving complete coverage: inspecting all POIs under constraints. Within aerospace literature, guidance methods can be broadly classified into three lines of work.
Across inspection planners, the metric relies on functions that are analytically computed. When illumination is considered, it is treated geometrically. This limits models to a line-of-sight check and assumes that this is an adequate measure of inspection. In sun-synchronous orbits, surfaces experience disproportionate illumination conditions: parts of the target may always be in shadow or dimly lit. Even with an analytical model, classical inspection methods are limited.
Experiments
A quantitative and qualitative analysis tests three different inspection probabilities.
Experimental Setup
The experimental setup in Isaac Sim used open-source NASA models of the Lunar Gateway as the target and a general satellite model adapted from CloudSat models as the chaser, along with Earth, Moon, and Sun modules.
Frequently Asked Questions
Why is autonomous spacecraft inspection important? It supports space situational awareness and proximity operations in constrained orbital environments, including debris removal, satellite repair, and in-orbit assembly and manufacturing.
What are the two coupled components of an inspection planner? A guidance system selects viewpoints, while a metric determines whether points of interest are considered inspected from those viewpoints.
Why can line-of-sight checks be insufficient for inspection? They do not adequately represent illumination conditions, which can leave parts of a target in shadow or dimly lit.
What models and environment were used in the experiments? The setup used a Lunar Gateway model as the target, a CloudSat-adapted satellite model as the chaser, and Earth, Moon, and Sun modules in Isaac Sim.