Spacecraft formation flying system design and controls for four nanosats mission

Youngbum Song, Sang-Young Park, Sangwon Lee, Pureum Kim, Eunji Lee, Jaejin Lee

Small-scale magNetosphere and Ionosphere Plasma Experiment (SNIPE) mission is aimed to observe a small-scale structure of the physical phenomena in a near-Earth environment. SNIPE mission comprises four 6U size nanosats that perform formation flying to meet the scientific objectives of the mission. In this study, we designed a formation flying system and validated it using numerical simulations to collect temporal and spatial differences of the physical phenomena for the SNIPE mission. The requirements for spacecraft formation flying are to pass the same point at different times and be located at different longitude points on the same latitude. Two types of formations which are an along-track formation for temporal observations and a cross-track formation for spatial observations are devised. The size of the formation decreases during the along-track formation phase and increases during the cross-track formation phase. Four types of orbit control were introduced to implement these formations and adjust the relative distances between the nanosats. Changing the shape and size of the formation exploits the effects of perturbations through orbit controls. The simulations were considered with several constraints to replicate the intended environments. The simulations also reflect the time differences between the orbit determination epoch and orbit control epoch, conditions in attitude control of nanosats, limitations of orbit control operation time to secure power stability, and errors in the thrust module. The numerical simulations demonstrated that each nanosat satisfied the mission requirements in a ΔV budget of 50 m/s. These results verified that the designed formation flying system meets the scientific objectives of SNIPE mission by changing the shape and size of the formation.

https://www.sciencedirect.com/science/article/pii/S0094576521002472?via%3Dihub