Speaker
Description
The growing number of Low Earth Orbit (LEO) objects has been an increasing concern for the Space Domain Awareness (SDA) community and the astronomy community. While the rapidly increasing number of satellites demands the development of a wide field-of-view SDA sensors that is capable of performing simultaneous detections, many recent studies have also highlighted the importance of understanding the near-earth environment for astronomy in optical, infrared, and radio wavelengths. Hence, we address these issues by using a low-frequency radio-interferometer, the Murchison Widefield Array (MWA), to perform space surveillance using passive radar techniques, whilst understanding its impact on FM band observations performed from the Murchison Radio-Observatory (home to the MWA and the future low-frequency Square Kilometer Array). In this talk, I will summarise the non-coherent passive radar capability developed using the MWA. We have developed and tested a LEO blind detection pipeline on archived MWA data, and we detect over 70 unique objects over multiple passes, demonstrating the MWA to be a valuable addition to the global SDA network. We detect LEO objects as small as 0.03 m2 radar cross-section and as far as ~1000 km. Additionally, we also detect FM reflections from Geminid meteors and aircrafts flying over the MWA. For many of the nearby detected objects, we split the MWA into two sub-arrays and perform line-of-sight range measurements using the parallax method. As part of this analysis, we show that the standard MWA RFI flagging strategy misses most of this RFI and that this should be a careful consideration for the SKA. We also demonstrate orbit determination and LEO catalog maintenance capability using the MWA, and the obtained orbital elements are in good agreement with the publicly released orbital elements by the Space Surveillance Network (SSN). Based on our understanding of the MWA SDA system, I conclude the talk by briefly describing the methods to mitigate the impact of FM reflecting LEO satellites on radio-astronomy observations, and how maintaining a catalog of FM reflecting LEO objects is in the best interest of both SDA and radio-astronomy.
