Shadow-Based Trajectory Estimation of a Deployable Payload

Deployable payloads have been used to expand mission opportunities and enable autonomous navigation and guidance under uncertain terrain conditions. A spacecraft may deploy an artificial marker toward the surface of the target body. An estimation of the deployment trajectory of markers can provide important information for guidance and navigation. We propose a method estimating the deployment trajectory using only images and evaluate its accuracy and reliability. In addition, to determine the spacecraft's relative attitude with respect to the asteroid surface, we introduce an attitude estimation method using the spacecraft's own shadow. The results shown in this paper confirm that the estimated trajectory is sufficiently accurate and thus the proposed method is a viable option for future missions for determining the trajectory of deployable payloads using only images of a deployment.