Matt Mayne, Dstl
Keywords: RCS, RF, Radar, Measurement, SDA, CubeSat
Abstract:
A CubeSat Radar Cross-Section (RCS) Measurement campaign (2023-2024) was conducted by Dstl, part of UK MOD, in support of UK Space Domain Awareness (SDA) research activities that aim to better understand satellite signatures. The measurement campaign involved assessing the RCS of a 6U (30x20x10cm) CubeSat with support from QinetiQ UK. This opportunity to capture the RCS of a real satellite and obtain truth data provides important understanding of the RCS levels that might be expected from typical CubeSat targets. Measurements took place on both the Flight Model (FM) and a representative Engineering Model (EM) were taken in an anechoic RCS measurement chamber. The RCS data was collected across a 3-40GHz frequency range, and included changes to the CubeSat orientation as well as studies on physical variations such as component deployment in order to produce a comprehensive dataset of the satellite.
Developing an understanding of the signatures of satellites is key in improving SDA capabilities, as it allows for an appreciation of how different satellites may appear to an observing radar. This campaign aimed to address the lack of truth satellite RCS data with this target of opportunity in collaboration with the CubeSat engineering team. A subset of real, FM-sourced measurements were blended with a broader set of measurements conducted on a representative EM. The EM was developed using a combination of FM spare parts as well as specifically procured and produced replacement and representative model components; this allowed for a greatly expanded measurement list. The CubeSat engineering team assisted in the transport and handling of the FM and provided safety instructions to minimise any risks to the FM during the campaign.
The test plan was developed in collaboration with QinetiQ UK with the initial FM measurements repeated on the EM version to allow for direct comparison. The CubeSat was altered and variation studies were carried out to assess both the impact on measured RF signature of replacing solar panels with metalised tape, as well as a Magnetometer in deployed and undeployed configurations. Understanding not only the signature of a satellite, but also how changes to the satellite affect its signature, is another key part of Space Domain Awareness as it is useful for determining whether the satellite has deployed instrumentation or been damaged or subject to some other disturbance.
The data collected has been subsequently processed and analysed to highlight and extract relevant features; identifying dominant sources of scatter on the satellite and hence determining their impact on RCS. Collection of a sweep of both frequency and azimuth data allows for the generation of Inverse Synthetic Aperture Radar (ISAR) imagery that makes it possible to extract information regarding the target’s size and orientation at the time of measurement. Dstl’s research into ISAR systems has been previously reported at AMOS [1]. This could allow for the identification of the orientation of a satellite on orbit including any changes to that orientation between orbits. This ability could potentially contribute to the fulfilment of a number of the UK government’s published SDA requirements, reported recently at AMOS [2, 3], particularly those related to object characterisation (UKSDA-SR-7300).
Once the CubeSat has been successfully launched and is in orbit, it is planned to track the satellite and collect data using a network of SDA research sensors, as well as through acquisition of data from commercial SDA providers and other sources. Opportunities will be outlined for interested parties to become involved in this effort. This data will be used to provide corresponding in-situ RCS measurement data to sit alongside both computer simulated data and the anechoic chamber RCS data collected in this campaign. This unique dataset will demonstrate a range of data collection methods of varying fidelity and complexity.
[1] Jennings-Bramly, T., Maxey, J., An End-to-End Signal Processing Chain for Low Earth Orbit Inverse Synthetic Aperture Radar Space Object Imaging, Proceedings of the Advanced Maui Optical and Space Surveillance (AMOS) Technologies Conference 2023.
[2] Cross Government Space Domain Awareness (SDA) Requirements Publication, 2023, https://www.gov.uk/government/publications/space-domain-awareness-requirements
[3] Kerr, E, UK SDA Requirements for a System of Systems in Support of the UK’s SDA Strategy, Proceedings of the Advanced Maui Optical and Space Surveillance (AMOS) Technologies Conference 2023.
Date of Conference: September 17-20, 2024
Track: Satellite Characterization