Analysis of Temporal and Structural Characteristics of Jovian Radio Emissions for Passive Radar Sounding of Jupiter's Icy Moons

Recent studies have proposed that Jovian decametric radiation (DAM) can be effectively exploited for probing the subsurface of Jupiter’s icy moons by using passive radio sounding. However, these studies were based on the assumption that Jovian noise is white and stationary. Therefore, additional investigations into the temporal stability, predictability, and spectral properties of Jovian noise are required to fully assess the potential of passive radar sounding and improve the acquisitions planning. In this article, we investigate these properties of the Jovian DAM to understand their impact on radar sounding performance. This is done by analyzing the recently available radio spectra acquired by the JUNO Waves instrument. Results are also evaluated for the specific case of the Radar for Icy Moon Exploration (RIME) and the Radar for Europa Assessment and Sounding: Ocean to Near-surface (REASON) that have been selected for European Space Agency (ESA) and NASA missions to Ganymede and Europa. Our results show that the Jovian DAM is not perfectly white, but no severe distortions in the range response should be expected. The results on spatiotemporal occurrence show that Jupiter’s DAM has a variable probability of occurrence, which is rather sporadic for some frequency ranges. The results on RIME and REASON flybys show that the Jovian DAM occurrence probability is relatively low for selected sub-Jovian flybys at Europa. For the RIME Ganymede orbital phase, a large number of high occurrence passive acquisition opportunities are expected. The experimental results also show that a large bandwidth receiver would enhance the chance of recording Jovian noise.