Herschel/HIFI observations of Mars: First detection of O2 at submillimetre wavelengths and upper limits on HCl and H2O2
Blommaert, J. A. D. L.; Küppers, M.; Thomas, N.; Hartogh, P.; Lellouch, E.; Encrenaz, T.; de Graauw, T.; Crovisier, J.; Feuchtgruber, H.; Teyssier, D.; Schieder, R.; Portyankina, G.; Biver, N.; Bockelée-Morvan, D.; Lis, D. C.; Bergin, E. A.; Blake, G. A.; Cernicharo, J.; Encrenaz, P.; Stutzki, J.; Decin, L.; Jehin, E.; Moreno, R.; Jarchow, C.; Medvedev, A. S.; Swinyard, B. M.; Rengel, M.; Sagawa, H.; Whyborn, N.; Cavalié, T.; Vandenbussche, B.; Sidher, S.; Kidger, M.; Waelkens, C.; Naylor, D. A.; Banaszkiewicz, M.; Lorente, R.; Helmich, F.; de Val-Borro, M.; Szutowicz, S.; Bensch, F.; Lara, L. -M.; Sánchez-Portal, M.; Fulton, T.; Roelfsema, P.; Billebaud, F.; Verdugo, E.; Błęcka, M. I.; Leduc, H. G.; Stern, J. A.
Germany, France, Japan, United Kingdom, United States, Poland, Spain, Belgium, Netherlands, Canada, Chile, Switzerland
Abstract
We report on an initial analysis of Herschel/HIFI observations of hydrogen chloride (HCl), hydrogen peroxide (H2O2), and molecular oxygen (O2) in the Martian atmosphere performed on 13 and 16 April 2010 (Ls ~ 77°). We derived a constant volume mixing ratio of 1400 ± 120 ppm for O2 and determined upper limits of 200 ppt for HCl and 2 ppb for H2O2. Radiative transfer model calculations indicate that the vertical profile of O2 may not be constant. Photochemical models determine the lowest values of H2O2 to be around Ls ~ 75° but overestimate the volume mixing ratio compared to our measurements.
Herschel is an ESA space observatory with science instruments provided by European-led Principal Investigator consortia and with important participation from NASA.