The AERO and VISTA CubeSat missions were designed to perform LF/HF radio interferometry from Low Earth Orbit (LEO) using Electromagnetic Vector Sensors (EMVSs) to investigate high-latitude aurora. An EMVS, in contrast to a traditional antenna, measures not only the magnitude but also the direction and polarization of incident radio waves, providing critical data for understanding space-based radio frequency interference and natural phenomena. This work extends ground-based radio science by exploring the feasibility of utilizing Ham Science Citizen Investigation (HamSCI)’s global network of citizen science stations to supplement and validate space-based observations. We use ray tracing models like PHaRLAP to simulate high-frequency (HF) propagation from terrestrial transmitters to a potential LEO satellite orbit.
Our exhaustive search of seasonal ionospheric conditions, modeled by the International Reference Ionosphere (IRI)-2020, has identified specific times when low-frequency HF signals (below 5 MHz) are most likely to penetrate the D-layer and reach LEO altitudes. This prediction is crucial for mission planning and signal acquisition. A key finding from our research is a method for cross-verifying ground-to-space and ground-to-ground links. Specifically, we identified an event on April 7, 2024, where a ray path from the KC4USV transmitter in Antarctica to our HamSCI receiver (W2NAF) in Pennsylvania has a point of commonality with a ray path that would propagate from KC4USV to a LEO satellite. This coincidental propagation path allows for a unique method of validating the modeled HF absorption by comparing the received signal strength at the W2NAF ground station to the expected signal strength at the AERO-VISTA satellite’s EMVS.
Ongoing work includes expanding our analysis to other high-latitude transmitters, such as CHU in Canada, to broaden our study of polar HF propagation. For future system enhancements, we propose using GNU Radio modules, specifically gr-leo, an open-source channel simulator of the Earth-Satellite system operation, developed by the Libre Space Foundation with European Space Agency funding, to explore the possible failures that may occur in space channel telecommunication, and gr-satnogs for real-world satellite data reception via the SatNOGS global network of ground stations. This would enable the development of Software Defined Radio (SDR) techniques to improve data fidelity and link budgets.
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