Analysis of NASA’s DSN Venus Express radio occultation data for year 2014
Edoardo Gramigna, Marzia Parisi, Dustin Buccino, Luis Gomez Casajus, Marco Zannoni, Paolo Tortora, Kamal Oudrhiri
The Venus Express Radio Science Experiment (VeRa) was part of the scientific payload of the Venus Express (VEX) spacecraft and was targeted at the investigation of Venus’ atmosphere, surface, and gravity field as well as the interplanetary medium. This paper describes the methods and the required calibrations applied to VEX-VeRa raw radio occultation selected data used to retrieve vertical profiles of Venus’ ionosphere and neutral atmosphere. In this work we analyze a set of 25 VEX, single-frequency (X-band), occultations carried out in 2014, recorded in open-loop at the NASA Deep Space Network. The calibrations are performed to correct the observed frequency for the major noise sources and errors, since any uncalibrated effects will bias the retrieval of atmospheric properties. We show that the temperature differences between the relativistic and non-relativistic Doppler shift solutions are lower than 0.5 K at 50 km altitude, so the relativity effects can safely be neglected. Our temperature, pressure and electron density vertical profiles are in agreement with previous studies available in the literature. Furthermore, our analysis shows that Venus’ ionosphere is more influenced by the day/night condition than the latitude variations, while the neutral atmosphere experiences the opposite. Our scientific interpretation of these results is based on two major responsible effects: Venus’ high thermal inertia and the zonal winds. Their presence within Venus’ neutral atmosphere determine why in these regions a latitude dependence is predominant on the day/night condition. On the contrary, at higher altitudes the two aforementioned effects are less important or null, and Venus’ ionosphere shows higher electron density peaks in the probed day-time occultations, regardless of the latitude.
Subjects: Earth and Planetary Astrophysics (astro-ph.EP); Instrumentation and Methods for Astrophysics (astro-ph.IM); Space Physics (physics.space-ph)
Cite as: arXiv:2102.08300 [astro-ph.EP] (or arXiv:2102.08300v1 [astro-ph.EP] for this version)
Submission history
From: Edoardo Gramigna
[v1] Tue, 16 Feb 2021 17:34:45 UTC (1,138 KB)
