Reply to Comment by F. Kenig, L. Chou, and D. J. Wardrop on “Evaluation of the Tenax Trap in the Sample Analysis at Mars Instrument Suite on the Curiosity Rover as a Potential Hydrocarbon Source for Chlorinated Organics Detected in Gale Crater” by Miller et al., 2015

Roger E. Summons (1) , Kristen Miller (1) , Benjamin Kotrc (1) , Imene Belmahadi (2) , Arnaud Buch (2) , Jennifer L. Eigenbrode (3) , Caroline Freissinet (4) , Daniel Glavin (3) , Cyril Szopa (4)

1 EAPS - Department of Earth, Atmospheric and Planetary Sciences [MIT, Cambridge]
2 LGPM - Laboratoire de Génie des Procédés et Matériaux - EA 4038
3 GSFC - NASA Goddard Space Flight Center
4 PLANETO - LATMOS

Kenig et al. comment on our 2015 reporting of laboratory analog experiments aimed at testing the stability of the hydrocarbon trap material used in the Sample Analysis on Mars (SAM) instrument on board the Curiosity Rover operating in Gale Crater on Mars. They propose chemical structures for some decomposition products of the Tenax TA polymer when it is exposed at high temperatures to the Cl2 and O2 gases formed by the thermal decomposition of perchlorate. Further, Kenig et al. propose that these decomposition products accumulate and then react further in cooler downstream sections of the SAM analytical pipeline to produce the chlorobenzene that was detected in the Cumberland mudstone of Gale Crater. However, numerous experiments conducted in the laboratory show that Tenax TA decomposition products only appear after repeated exposure to much higher levels of Cl2 and O2 than those seen by the flight instrument. Moreover, the sequence of chlorobenzene detections during gas chromatography‐mass spectrometry experiments conducted on Mars cannot be explained by Tenax TA decomposition, nor can the detection of chlorobenzene in Evolved Gas Analysis experiments that involve pathways devoid of Tenax TA. Kenig et al. are incorrect in their assertion that Tenax TA decomposition products can account for the chlorobenzene detected on Mars by SAM.

Domaines: Astrophysique [astro-ph]

Roger E. Summons, Kristen Miller, Benjamin Kotrc, Imene Belmahadi, Arnaud Buch, et al.. Reply to Comment by F. Kenig, L. Chou, and D. J. Wardrop on “Evaluation of the Tenax Trap in the Sample Analysis at Mars Instrument Suite on the Curiosity Rover as a Potential Hydrocarbon Source for Chlorinated Organics Detected in Gale Crater” by Miller et al., 2015. Journal of Geophysical Research. Planets, 2019, 124 (2), pp.648-650. ⟨10.1029/2018JE005641⟩. ⟨insu-02083375⟩