Satellite Bus Market Size, Share & COVID-19 Impact Analysis, By Size (Small Satellite, Medium Satellite, Heavy Satellite), By Subsystem (Structures and Mechanisms, Thermal Control System, Electric Power System (EPS), Altitude Control System, Telemetry Tracking & Command (TT&C), Flight Software, Propulsion System), By Application (Earth Observation & Meteorology, Communication, Scientific Research & Exploration, Surveillance & Security, Mapping & Navigation), and Regional Forecast, 2021-2028