Upper limits for phosphine (PH₃) in the atmosphere of Mars

Kevin Olsen (1) , Alexander Trokhimovskiy (2) , Ashwin Braude (3) , Oleg Korablev (2) , Anna Fedorova (2) , C. F. Wilson (1) , M. R. Patel (4) , Patrick G. J. Irwin (1) , Franck Montmessin (3) , Franck Lefèvre (3) , Lucio Baggio (3) , J. Alday (1) , Denis A. Belyaev (2) , A. Patrakeev (2) , A. V. Shakun (2)

1 Department of Physics [Oxford]
2 IKI - Space Research Institute of the Russian Academy of Sciences
3 PLANETO - LATMOS
4 School of Physical Sciences [Milton Keynes]

Phosphine (PH3) is proposed to be a possible biomarker in planetary atmospheres and has been claimed to have been observed in the atmosphere of Venus, sparking interest in the habitability of Venus’s atmosphere. Observations of another biomarker, methane (CH4), have been reported several times in the atmosphere of Mars, hinting at the possibility of a past or present biosphere. The Atmospheric Chemistry Suite on the ExoMars Trace Gas Orbiter has a spectral range that includes several absorption lines of PH3 with line strengths comparable to previously observed CH4 lines. The signature of PH3 was not observed in the 192 observations made over a full Martian year of observations, and here we report upper limits of 0.1–0.6 ppbv.

Domaines: Planète et Univers [physics]

Kevin Olsen, Alexander Trokhimovskiy, Ashwin Braude, Oleg Korablev, Anna Fedorova, et al.. Upper limits for phosphine (PH₃) in the atmosphere of Mars. Astronomy and Astrophysics - A&A, 2021, 649, L1 (5p.). ⟨10.1051/0004-6361/202140868⟩. ⟨insu-03208720v2⟩