Phosphine In The Venusian Atmosphere: A Strict Upper Limit From SOFIA GREAT Observations

By Keith Cowing
Press Release
October 25, 2022
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Phosphine In The Venusian Atmosphere: A Strict Upper Limit From SOFIA GREAT Observations
JCMT and ALMA spectra from the original Venus study of Greaves et al. (2021a) (top two traces), showing the spectral region in the vicinity of the PH3 J = 1–0 line at 266.945 GHz. The lower four traces show disk-averaged ALMA spectra derived from the same data using different calibration and reduction methodologies by different authors, as explained by Villanueva et al. (2021) and Greaves et al. (2021b). For reference, the black dashed trace shows the 1 ppb PH3 spectral model (upper limit) from Villanueva et al. (2021). The Greaves et al. (2021a) and (2021b) ALMA spectra differ considerably, due to improper calibration of the 2021a data. — astro-ph.EP

The presence of phosphine (PH3) in the atmosphere of Venus was reported by Greaves et al. (2021a), 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 GREAT instrument aboard the SOFIA aircraft, over three flights conducted in November 2021.

Multiple PH3 transitions were targeted at frequencies centered on 533 GHz and 1067 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.

M. A. Cordiner, G. L. Villanueva, H. Wiesemeyer, S. N. Milam, I. de Pater, A. Moullet, R. Aladro, C. A. Nixon, A. E. Thelen, S. B. Charnley, J. Stutzki, V. Kofman, S. Faggi, G. Liuzzi, R. Cosentino, B. A. McGuire

Comments: Accepted for publication in Geophysical Research Letters
Subjects: Earth and Planetary Astrophysics (astro-ph.EP)
Cite as: arXiv:2210.13519 [astro-ph.EP] (or arXiv:2210.13519v1 [astro-ph.EP] for this version)
Submission history
From: Martin Cordiner PhD
[v1] Mon, 24 Oct 2022 18:18:51 UTC (1,492 KB)

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