Estimating detectability of phosphine in the Venusian atmosphere using spectral modeling

This study aims to determine if phosphine is detectable in the atmosphere of Venus and at what spectral wavelengths this may be possible. Phosphine is considered a biosignature, and its presence may imply the existence of life on Venus. The quantity of phosphine present in the atmosphere of Venus is a controversial subject and has been investigated using various in situ and Earth-based measuring devices. Due to disagreement in past research concerning detected concentrations of phosphine, further research into the possible detectability of phosphine on Venus is warranted. In this project, version 19 of the PHOENIX spectra modeling software is used to create synthetic spectra of the Venusian atmosphere. Physical parameters (temperature stratification, pressure stratification, atomic lines, molecular lines, continuum cross-section and irradiation) of the Venusian atmosphere and its environment are input into the model. The concentration of phosphine is manipulated and the synthetic spectral output produced is observed. In a synthetic atmosphere with 20 ppb of phosphine the chemical can be detected at ~1.123x10⁷ Å(~266.94 GHz), which agrees with empirical telescopic observations. Phosphine may also be detected at ~1.134x10⁷ Å (~264.35 GHz) and ~ 1.367x10⁷ Å (~219.25 GHz). The latter will potentially provide the strongest signal and can be investigated further by telescopes assuming that there are not many sources of noise at this wavelength.