Improved Sensitivity for Space Domain Awareness Observations with the Murchison Widefield Array

New candidate detections (steady reflections) in range vs RCS parameter space using white circle markers. The background image is the detection summary of the blind survey performed in Prabu, Hancock, Zhang, et al., 2020. Note that the objects detected outside the primary beam were not considered in the histograms plotted along the right and lower axes.

Our previously reported survey of the Low Earth Orbit (LEO) environment using the Murchison Widefield Array (MWA) detected over 70 unique Resident Space Objects (RSOs) over multiple passes, from 20 hours of observations in passive radar mode.

In this paper, we extend this work by demonstrating two methods that improve the detection sensitivity of the system. The first method, called shift-stacking, increases the statistical significance of faint RSO signals through the spatially coherent integration of the reflected signal along the RSO's trajectory across the sky. This method was tested on the observations used during our previous blind survey, and we obtained a 75% increase in the total number of detections. The second method re-focuses the MWA to the near-field RSO's position (post-observation), by applying a complex phase correction to each visibility to account for the curved wave-front.

The method was tested successfully on an MWA extended array observation of an ISS pass. However, the method is currently limited by signal de-coherence on the long-baselines (due to the hardware constraints of the current correlator). We discuss the sensitivity improvement for RSO detections we expect from the MWA Phase 3 correlator upgrade. We conclude the paper by briefly commenting on future dedicated Space Domain Awareness (SDA) systems that will incorporate MWA technologies.

Steve Prabu, Paul J Hancock, Xiang Zhang, Steven J Tingay, Torrance Hodgson, Brian Crosse, Melanie Johnston-Hollitt

Comments: Accepted in Advances in Space Research. 16 pages, 10 figures, and 1 Table
Subjects: Instrumentation and Methods for Astrophysics (astro-ph.IM); Earth and Planetary Astrophysics (astro-ph.EP)
Cite as: arXiv:2205.05868 [astro-ph.IM] (or arXiv:2205.05868v1 [astro-ph.IM] for this version)
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Submission history
From: Steve Raj Prabu [view email]
[v1] Thu, 12 May 2022 03:38:09 UTC (6,859 KB)

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