Constellation and data link design for a nano-satellite Earth observation system

Abstract

A constellation of nano-satellites in low Earth orbits can provide complementary Earth observation (EO) data to current large satellite systems in a cost-efficient way. It increases coverage and reduces revisit time compared to current EO systems with few large satellites. We combine constellation and link simulation tools to study the design trade-offs for a constellation of EO nano-satellites at sun-synchronous orbits (SSOs), carrying a hyperspectral camera over continental Europe. Coverage, revisit time, satellite throughput, and scheduling effects are studied for several sets of parameters. We show that 22 satellites evenly distributed on a plane on an SSO at 499.8 km altitude, with a repeat cycle of 5 days, can provide 100 % of accumulated coverage in 27 hours while collecting data only during the daytime. Data download requires scheduling at ground stations (GSs) when a GS has just one antenna and several satellites are in sight. A GS located after the data collection zone reduces the age of information but requires on-board data storage. The developed simulation environment can be used to design and study new constellations in terms of coverage, revisit time, downlink throughput, and age of information.