Space-Domain Awareness Using Over-the-Horizon Radar

Abstract

The use of existing over-the-horizon radar (OTHR) systems as space-domain awareness (SDA) sensors is experimentally evaluated by tracking several International Space Station (ISS) passes under different solar activity conditions. Using range and Doppler measurements, a single-frequency ionospheric correction technique is introduced and is shown to be critical to the implementation of accurate SDA using OTHR. This single-frequency technique is also useful for monitoring the ionosphere total electron content (TEC) using a space target without very accurate prior knowledge of its orbital parameters. All measurements and orbit determination results are validated with truth data provided by the National Aeronautics and Space Administration (NASA). Although it is determined that angle-of-arrival (AOA) measurements are not accurate enough for accurate SDA, orbit determination using single-pass observations from a single site are shown to yield position and velocity errors that can be better than 500 m and 0.7 m/s with a radar bandwidth of only 10 kHz. Accurate SDA using OTHR is determined to be possible especially at night or in periods of solar minimum.