Large Baseline Bistatic Radar Imaging for Space Domain Awareness

Bistatic radars with long baselines are gaining popularity due to the increased interest in Space Domain Awareness, but require significant investment due to the need for large antenna apertures, low noise temperatures, and synchronized clocks. However, radio telescopes can be paired with high-power radars to create long baseline bistatic-multistatic radar networks. This paper describes novel long baseline bistatic measurements using the Millstone Hill Radar (MHR) in the USA and receivers in multiple antennas of the e-MERLIN array in the United Kingdom and the Westerbork Synthesis Radio Telescope (WSRT) in the Netherlands. When provided with basic information about the transmitted waveform, multiple receivers can detect, identify, and track multiple targets. The paper also presents a framework for imaging tumbling targets, demonstrating its effectiveness on real data collected by a novel system concept. This framework integrates coherent integration and Doppler processing techniques to improve signal-to-noise ratio, estimate and correct target motion, and estimate the rotation period and dimensions of tumbling targets, resulting in a clear image of the space object. The presented framework and the proposed system concept have potential to improve bistatic imaging, leading to better characterization of objects in Earth orbits undergoing complex motion, with significant implications for applications such as space domain awareness, space traffic management, and space object characterization.