A Low Frequency Blind Survey of the Low Earth Orbit Environment using Non-Coherent Passive Radar with the Murchison Widefield Array

TL;DR

This study demonstrates the use of the Murchison Widefield Array as a passive radar system to detect and survey objects in Low Earth Orbit using FM signals, expanding space situational awareness capabilities.

Contribution

The paper introduces a novel application of the MWA as a non-coherent passive radar for LEO object detection, achieving successful identification of multiple objects over 20 hours of data.

Findings

Detected 74 unique LEO objects with ranges up to 977 km

Identified objects including satellites and debris, some non-operational

Validated the MWA's performance against previous feasibility predictions

Abstract

We have extended our previous work to use the Murchison Widefield Array (MWA) as a non-coherent passive radar system in the FM frequency band, using terrestrial FM transmitters to illuminate objects in Low Earth Orbit LEO) and the MWA as the sensitive receiving element for the radar return. We have implemented a blind detection algorithm that searches for these reflected signals in difference images constructed using standard interferometric imaging techniques. From 20 hours of archived MWA observations, we conduct a survey of LEO, detecting 74 unique objects over multiple passes and demonstrating the MWA to be a valuable addition to the global Space Domain Awareness network. We detected objects with ranges up to 977 km and as small as 0.03 m^2 radar cross section. We found that 30 objects were either non-operational satellites or upper-stage rocket body debris. Additionally, we also detected FM reflections from Geminid meteors and aircraft flying over the MWA. Most of the detections of objects in LEO were found to lie within the parameter space predicted by previous feasibility studies, verifying the performance of the MWA for this application.