CO 2 ice is mainly found at high latitude in form of seasonal cap (Andrieu et al., 2018 Brown et al., 2010, 2012 Herr & Pimentel, 1969 Kieffer & Titus, 2001 Langevin et al., 2007 Larson & Fink, 1972 Schmidt et al., 2009, 2010) and its physical and spatial characteristics strongly affect (and are affected by) the climatology of its gaseous counterpart (Forget, 1998 Forget et al., 1995 Leighton & Murray, 1966). The presence of CO 2 ice on the surface has been widely investigated remotely in different spectral ranges by instruments aboard several missions, such as Mariner 9/IRIS (Hanel et al., 1972), Viking/IRTM (Kieffer et al., 1972), Mars Global Surveyor/TES (Christensen et al., 2001), Mars Express OMEGA (Bibring et al., 2004) and PFS (Formisano et al., 2005) spectrometers, and the Mars Reconnaissance Orbiter/CRISM instrument (Murchie et al., 2007). Through radiative transfer considerations on these detections we find that the 2.35 μm absorption feature of CO 2 ice clouds is possibly sensitive to nm‐sized ice grains.ĬO 2 is the main component of the Martian atmosphere, in which temperatures can be low enough to induce local condensation of the molecule as ice/snow on the surface or as clouds at high altitude (Aoki et al., 2018 Clancy & Sandor, 1998 Clancy et al., 2007, 2019 Langevin et al., 2007 McConnochie et al., 2010 Montmessin et al., 2007 Schmidt et al., 2009, 2010 Schofield et al., 1997 Vincendon et al., 2011).

We find that the clouds hypothesis is preferable on the basis of surface temperature, local time and grain size considerations, resulting in the first detection of CO 2 ice clouds through the study of this spectral range. Occurrences of CO 2 ice spectra are also detected at low latitudes and we discuss about their interpretation as daytime high altitude CO 2 ice clouds as opposed to surface frost. We find that the narrow 2.35 μm absorption band, spectrally well covered by LNO order 189, offers the most promising potential for the retrieval of CO 2 ice microphysical properties. We obtain latitudinal‐seasonal maps for CO 2 ice in both polar regions, in overall agreement with predictions by a general climate model and with the Mars Express/OMEGA spectrometer Martian Years 27 and 28 observations. We study the strong CO 2 ice absorption band at 2.7 μm and the shallower band at 2.35 μm taking advantage of observations across Martian Years 34 and 35 (March 2018 to February 2020), straddling a global dust storm.

We investigate the information content of the Limb, Nadir, and Occultation (LNO) infrared channel of NOMAD and demonstrate how spectral orders 169, 189, and 190 can be exploited to detect surface CO 2 ice. The Nadir and Occultation for MArs Discovery (NOMAD) instrument suite aboard ExoMars/Trace Gas Orbiter spacecraft is mainly conceived for the study of minor atmospheric species, but it also offers the opportunity to investigate surface composition and aerosols properties.

Mars miner 2 map