Reprocessing of Pioneer Venus Orbiter radio occultation data: Principles and methodology using a test case

In preparation for forthcoming Venus missions—ESA's EnVision, NASA's DAVINCI and VERITAS, and ISRO's Shukrayaan—a reassessment of Pioneer Venus Orbiter (PVO) radio occultation (ORO) data was conducted to strengthen the long-term atmospheric database. A total of 206 open-loop files from the Deep Space Network (DSN) ground stations (1978–1982) were identified with the Planetary Data System (PDS), of which 154 correspond to ORO measurements covering 62 occultation events. Data availability is strongly biased toward the first occultation season (54 events between December 1978 and February 1979), with only eight events from the fourth season and no original files from seasons two, three, and five–six. Reprocessing employed modern software pipelines and updated SPICE orbit kernels from PVO to generate vertical profiles of temperature and electron density. For DOY 002, 1979, reprocessed profiles were directly compared against original PVO products and Venus Express VeRa profiles. Results show: (i) excellent agreement in adiabatic lapse rates below the tropopause, (ii) a persistent isothermal region of ~240 K spanning ~15 km above the tropopause, and (iii) nearly identical temperature structures up to an altitude of 90 km radius, with a systematic vertical offset of 3.7 km. Electron density comparisons reveal a well-pronounced V2 layer at 147.5 km (LT = 20:30, SZA = 94°), consistent between reprocessed S-band and differential Doppler profiles, with peak densities matching within uncertainties. The V1 layer, if correctly identified, appears detached at ~130 km with a peak of ~5000 el cm −3 . These results confirm that the reprocessed ORO dataset, correctly processed, provides physically robust atmospheric profiles and demonstrate that the spin-stabilized PVO platform yields higher internal stability compared to the three-axis stabilized bodies of later missions such as Venus Express and Mars Express. • Pioneer Venus Orbiter radio sounding of the Venus atmosphere and ionosphere are reanalyzed. • Reprocessing of the original raw radio science data from 1979 based on new Pioneer Venus orbit file. • Altitude difference between reprocessed data and original temperature and electron density profiles. • Reprocessed temperature profiles show excellent agreement with VEX-VeRa radio science temperature data from the Venus Express mission 30 years later. • Original temperature, reprocessed temperature and VEX-Vera profiles are very well consistent when shown in a pressure versus temperature diagram.