Phosphine in the Venusian Atmosphere: A Strict Upper Limit From SOFIA GREAT Observations
Martin Cordiner, Gerónimo Villanueva, H. Wiesemeyer, Stefanie N. Milam, Imke de Pater, Arielle Moullet, R. Aladro, C. A. Nixon, Alexander E. Thelen, S. B. Charnley, J. Stützki, Vincent Kofman, Sara Faggi, Giuliano Liuzzi, Richard Cosentino, Brett A. McGuire
Abstract
Abstract The presence of phosphine (PH 3 ) in the atmosphere of Venus was reported by Greaves et al. (2021, https://doi.org/10.1038/s41550-020-1174-4 ), based on observations of the J = 1–0 transition at 267 GHz using ground‐based, millimeter‐wave spectroscopy. This unexpected discovery presents a challenge for our understanding of Venus's atmosphere, and has led to a reappraisal of the possible sources and sinks of atmospheric phosphorous‐bearing gases. Here we present results from a search for PH 3 on Venus using the German REceiver for Astronomy at Terahertz Frequencies instrument aboard the Stratospheric Observatory for Infrared Astronomy aircraft, over three flights conducted in November 2021. Multiple PH 3 transitions were targeted at frequencies centered on 533 and 1,067 GHz, but no evidence for atmospheric PH 3 was detected. Through radiative transfer modeling, we derived a disk‐averaged upper limit on the PH 3 abundance of 0.8 ppb in the altitude range 75–110 km, which is more stringent than previous ground‐based studies.