Phosphine in the Venusian Atmosphere: A Strict Upper Limit From SOFIA GREAT Observations. Issue 22 (22nd November 2022)

• Record Type: Journal Article
• Authors: Cordiner, M. A.; Villanueva, G. L.; Wiesemeyer, H.; Milam, S. N.; de Pater, I.; Moullet, A.; Aladro, R.; Nixon, C. A.; Thelen, A. E.; Charnley, S. B.; Stutzki, J.; Kofman, V.; Faggi, S.; Liuzzi, G.; Cosentino, R.; McGuire, B. A.
• Is Part Of: Geophysical research letters. Volume 49:Issue 22(2022)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2022-11-22
• Subjects: Venus -- atmosphere -- phosphine -- submillimeter -- spectroscopy -- far‐infrared; Geophysics -- Periodicals; Planets -- Periodicals; Lunar geology -- Periodicals; 550
• DOI: 10.1029/2022GL101055
• Languages: English
• ISSNs: 0094-8276

Abstract

Abstract: The presence of phosphine (PH3 ) 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 PH3 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 PH3 transitions were targeted at frequencies centered on 533 and 1, 067 GHz, but no evidence for atmospheric PH3 was detected. Through radiative transfer modeling, we derived a disk‐averaged upper limit on the PH3 abundance of 0.8 ppb in the altitude range 75–110 km, which is more stringent than previous ground‐based studies. Plain Language Summary: We performed observations using a unique, flying telescope—the Stratospheric Observatory for Infrared Astronomy—to search for a gas called phosphine (PH3 ) in the atmosphere of Venus, which has been suggested to be an indicator for life. Our observations showed no evidence of PH3, in contrast to the original claim, and we provide a stringent upper limit on its abundance. Two other recent studies using different telescopes also found no evidence for PH3 on Venus, in agreement with our present result. Key Points: A recent detection of phosphine (PH3 ) (a possible biomarker) on Venus at millimeter wavelengths has been called into question by subsequent work We performed far‐infrared spectroscopic observations of Venus using the German REceiver for Astronomy at Terahertz Frequencies instrument onboard the Stratospheric Observatory for Infrared Astronomy aircraft PH3 was not detected, and a strict upper limit on its atmospheric abundance of 0.8 ppb was derived between 75 and 110 km