Retrieving sulphuric acid profile of Venus atmosphere from radio occultation data of Akatsuki spacecraft

Abstract

This research aims to examine the distribution of sulfuric acid H2SO4 in the Venusian atmosphere by employing radio occultation (RO) measurements. As a well-established method for atmospheric and ionospheric profiling, RO analyzes changes in frequency, phase, and power received at ground stations. In this study, we utilized one-way downlink single-frequency (X-band: 3.6cm wavelength) radio signals transmitted from the Ultra stable Oscillator, a radio science payload onboard the Akatsuki spacecraft, and received at the UDSC-64M receiver during occultation year 2020. Our primary objective was to develop a signal processing technique for data analysis and the subsequent retrieval of altitude and latitudinal distribution of H2SO4 in Venus’s atmosphere. The outcomes of this research enhance our understanding of neutral atmospheric profiles and shed light on the formation of dense Venusian clouds. Our results reveal that equatorial and mid-latitude regions exhibit an H2SO4 concentration of 4.15 ppm, with peak concentrations reaching 12 ppm, while higher latitudes average 4.60 ppm with peaks between 13-15 ppm. We also identified the presence of H2SO4 gas at higher altitudes in the 60°-70° region, indicating the existence of thicker clouds. The data gathered by the Akatsuki probe o↵ers valuable insights into Venus’s atmospheric conditions, and our investigation contributes to the ongoing e↵orts to unravel the mysteries of this intriguing planet.