GPS-based satellite formation flight simulation and applications to ionospheric remote sensing

The Virginia Tech Formation Flying Testbed (VTFFTB), a GNSS-based hardware-in-the-loop (HIL) simulation testbed for spacecraft formation flight, is developed and applied to ionospheric remote sensing. The current VTFFTB consists of GNSS RF hardware signal simulators, multi-constellation multi-frequency GNSS receivers, a navigation and control system, an STK visualization system, and an ionospheric remote sensing system. GPS signals are emulated using GNSS simulator scenarios that include ionospheric phenomena. A formation of two spacecraft ("chief" and "deputy") is considered. GNSS receiver data are used to produce space-based Total Electron Content (TEC) and scintillation measurements. A reference low Earth orbit (LEO) scenario is benchmarked with past simulation results to validate functionality. A LEO formation flying mission is designed to probe two Equatorial Spread F (ESF) scenarios with plasma bubbles. The results investigate the structure of ionospheric irregularities and demonstrate that the GPS-based satellite formation is able to measure vertical electron density by differencing 1D GPS vertical TEC.