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This study designs a multistatic synthetic aperture radar (SAR) formation-flying system for very-high-resolution stripmap imaging (VHRSI) using manufacturable SAR microsatellites. Multistatic SAR formation specifications for VHRSI are derived based on the SAR image theory. For the simultaneous multi-satellite operation, the advantages of the autonomous orbit and attitude control are prominent in terms of the workload of the ground station or the efficient performance of missions. Therefore, the autonomous relative-orbit-control algorithm using relative orbital elements is developed to maintain the designed multistatic SAR formation. Additionally, an autonomous attitude-control algorithm for multistatic SAR imaging is designed by applying the optimal right-ascension of the descending node (RADN) sector concept. Finally, the resolution improvement of VHRSI is verified through multistatic SAR imaging simulations. The multistatic SAR formation is designed with three satellites separated by 7.5 km each in the along-track direction. Autonomous relative orbit control maintains the relative position error within 45 m (3σ). Additionally, the autonomous attitude control simulation verifies that the satellites perform attitude maneuvers suitable for the operation mode, and the pointing error is maintained within 0.0035° (3σ). The spatial resolution of the multistatic SAR system for VHRSI is 0.95 × 0.96 m, which satisfies the very-high-spatial-resolution requirement.

This study designs and analyzes satellite formation flying concepts for the Small scale magNetospheric and Ionospheric Plasma Experiments (SNIPE) mission, that will observe the near-Earth space environment using four nanosats. To meet the requirements to achieve the scientific objectives of the SNIPE mission, three formation flying concepts are analyzed: a crossshape formation, a square-shape formation, and a cross-track formation. Of the three formation flying scenarios, the crosstrack formation scenario is selected as the final scenario for the SNIPE mission. The result of this study suggests a relative orbit control scenario for formation maintenance and reconfiguration, and the initial relative orbits of the four nanosats meeting the formation requirements and thrust limitations of the SNIPE mission. The formation flying scenario is validated by calculating the accumulated total thrust required for the four nanosats. If the cross-track formation scenario presented in this study is applied to the SNIPE mission, it is expected that the mission will be successfully accomplished.

This paper presents the operational scenario of the CANYVAL-X (Cubesat Astronomy by NASA and Yonsei using Virtual telescope ALignment eXperiment) mission and along with the resulting lessons learned from the early operation. The objective of this demonstration mission is to verify a vision alignment system with two CubeSats in low Earth orbit. The CubeSats were launched on 12 January 2018 at Sriharikota launch site by PSLV-C40. CubeSat Yonsei team designed the operational scenario and developed automatic communication programs to manage normal CubeSat operation. After 43 days from the launch, the first beacon signal from the 2U CubeSat was received at the ground station in Yonsei University. The ping between the CubeSat and the ground station was used to check the FM communication. Repetitive attempt was made to download the log file from the first reception of the beacon signal. Currently, telecommand and telemetry are not carried out successively since the FM communication of the ground station is acting abnormal. From these experience during the early operation of CANYVAL-X, CubeSat Yonsei team learned valuable lessons for the future mission such as the beacon carriage and the storage management design strategy.