a Composition Model of Venus' Upper Atmosphere and its Implications for Future Venus Missions Striving to Detect Heavy Noble Gases and Phosphine In-Situ
Abstract
We present an exospheric model of Venus upper atmosphere, similar to the ones our group previously applied to other planetary bodies, moons and comets, e.g., Mercury, Jupiter and its icy moons as well as Earth's moon. Those models were used to define the requirements for the mass spectrometers on board ESA's BepiColombo and the JUICE (JUpiter ICy moons Explorer) missions. By including Venus in our code, we fill a gap and demonstrate the utility of future in-situ measurements. In regard to the recent reports of phosphine detection in Venus cloud decks we make predictions of its detectability above 80 km. We present density profiles of 24 major species of the thermal atmosphere and 4 species of the hot atmosphere. The focus lies on the heavy noble gases krypton and xenon as well as phosphine. Heavy noble gases have not been measured on Venus yet, but as they are chemically inert and not affected by Jeans escape, knowing their abundance would yield valuable information about the planet's evolution. Phosphine on the other hand was just recently detected in the cloud decks and might indicate the presence of anaerobic microbes in the sulfuric acid cloud droplets. Further investigation into this subject is required, and we present density profiles of PH$ _{3}$ above the cloud deck. The short lifetime of phosphine is taken into account and we discuss the requirements for future Venus observations by spacecraft if striving for a phosphine detection. We also include possible measurements in form of modelled mass spectra for the BepiColombo flyby in August 2021, the JUICE flyby in October 2023 and the proposed EnVision mission by ESA covering all atmospheric species that are potentially detectable.
- Publication:
-
43rd COSPAR Scientific Assembly. Held 28 January - 4 February
- Pub Date:
- January 2021
- Bibcode:
- 2021cosp...43E.785G