Title: Do The Clouds of Venus Contain Phosphine?

Abstract: The observation of a 266.94 GHz feature in the Venus spectrum has been attributed to phosphine (PH3) in the Venus clouds, suggesting unexpected geological, chemical or even biological processes. Since both PH3 and sulfur dioxide (SO2) are spectrally active near 266.94 GHz, the contribution to this line from SO2 must be determined before it can be attributed, in whole or part, to PH3. An undetected SO2 reference line, interpreted as an unexpectedly low SO2 abundance, suggested that the 266.94 GHz feature could be attributed primarily to PH3. However, the low SO2 and the inference that PH3 was in the Venus cloud deck runs counter to the supporting observations and our existing understanding of the Venus environment. In this talk I will review the discovery papers and describe a comprehensive research effort to independently analyze both the data and the interpretation that supports the claimed PH3 discovery. I will describe an alternative hypothesis—that typical amounts of Venus SO2 can fully explain both the detection and non-detection of absorption lines in the discovery data—and support this hypothesis via comparison with other results put forward by the observational and Venus communities. This study further emphasizes the importance of understanding planetary context when searching for, and interpreting, potential signs of life beyond the Earth.

Short Bio: Victoria Meadows is an astrobiologist and planetary astronomer whose research interests focus on acquisition and analysis of remote-sensing observations of planetary atmospheres and surfaces. In addition to studying planets within our own Solar System, she is interested in exoplanets, planetary habitability and biosignatures. Since 2000, she has been the Principal Investigator for the Virtual Planetary Laboratory Lead Team of the NASA Astrobiology Institute. Her NAI team uses models of planets, including planet-star interactions, to generate plausible planetary environments and spectra for extrasolar terrestrial planets and the early Earth. This research is being used to help define signs of habitability and life for future extrasolar terrestrial planet detection and characterization missions.