First Results from Atmospheric Observations of CO2, H2O, and CO from Supercam on Mars2020-Pereverance Rover
F. Montmessin, LATMOS, Guyancourt, France, (franck.montmessin@latmos.ipsl.fr), T. McConnochie, Space
Science Institute, Boulder, USA, T. Fouchet, LESIA, Paris Observatory, France, C. Royer, LESIA, Paris Observatory, France, E. W. Knutsen, LATMOS, Guyancourt, France, T. Bertrand, LESIA, Paris Observatory,
France, O. Forni, IRAP, CNRS, Université de Toulouse, UPS-OMP, Toulouse, Franc,e P. Pilleri, IRAP, CNRS,
Université de Toulouse, UPS-OMP, Toulouse, France, O. Gasnault, IRAP, CNRS, Université de Toulouse,
UPS-OMP, Toulouse, France, G. Lacombe, LATMOS, Guyancourt, France, J. Lasue, IRAP, CNRS, Université
de Toulouse, UPS-OMP, Toulouse, France, C. Legett, Los Alamos National Laboratory, Los Alamos, NM,
USA, 6University of Maryland, College Park, MD, USA, M. T. Lemmon, Space Science Institute, Boulder,
USA, T. Newell, Los Alamos National Laboratory, Los Alamos, NM, USA, 6University of Maryland, College
Park, MD, USA, D. M. Venhaus, Los Alamos National Laboratory, Los Alamos, NM, USA, 6University of Maryland, College Park, MD, USA, S. Maurice, IRAP, CNRS, Université de Toulouse, UPS-OMP, Toulouse,
France, R. C. Wiens, Los Alamos National Laboratory, Los Alamos, NM, USA, 6University of Maryland, College Park, MD, USA, and the SuperCam team.

Introduction:
The SuperCam instrument onboard the Mars2020Perceverance rover [1, 2] has the capability of performing several active and passive techniques. Passive spectroscopic measurements of the atmosphere
are possible in the 0.4-0.85 (VIS) and the 1.3-2.6 (IR)
micron ranges [3, 4]. Since landing in Jezero crater in
February 2021, SuperCam has performed numerous
atmospheric observations.
The technique used is called “passive sky”, and
has already been successfully conducted by ChemCam on the Mars Science Laboratory rover [5]. SuperCam extends on the Capabilities of ChemCam, by
also being able to probe the atmosphere in the critical
IR window which includes absorption and scattering
characteristics of gases and aerosols of particular interest.
Passive sky measurements have typically been
carried out every two weeks, providing a consistent
monitoring of key quantities such as CO2, O2, H2O
and CO abundances along with cloud and aerosol
properties. Particular attention was given to joint
measurements of O2 and CO, as they provide unique
insights into the Martian chemical cycle and have
never before been measured at the same time from the
surface. The results presented here will focus on the
retrieval of CO2, H2O and CO volume mixing ratios.
Primary science objectives. CO has been observed
[6] to follow the expected seasonal cycle of a chemically-inert non-condensable trace gas. To resolve the
expected seasonal cycle of CO, our target measurement precision is +/- 100 ppm. Near-surface abundances of water vapor are notoriously difficult to obtain, but are particularly valuable for assessing possible surface-atmosphere exchange processes. Our primary objective for water vapor is therefore to routinely sample the daytime H2O column, for direct
comparison with nighttime mixing ratio measurements made by the Mars 2020 Mars Environmental

Dynamics Analyzer (MEDA) humidity sensor [7], but
also to help connect in-situ measurement by MEDA
with measurements from orbit. We target a precision
for precipitable water column of +/- 1 precipitable microns, comparable to ChemCam [8].

Method:
The SuperCam instrument suite consists of a
ChemCam-heritage reflection spectrometer, 385–465
nm (“violet”), < 0.2 nm res. [3], an intensified transmission spectrometer, 536–853 nm, 0.3 – 0.7 nm res.
[3], and an acousto-optic-tunable-filter (AOTF) based IR spectrometer, 1300 – 2600 nm, 20 – 30 cm1
res. [2, 4].
The passive sky observing strategy is the same as
the ChemCam MSL approach, where SuperCam is
pointed to the sky at two different elevation angles
thus yielding two different path lengths through the
absorbing gas of interest. By ratioing the two obtained
spectra, one removes most instrument response and
solar spectrum uncertainties that are ~10x and ~100x
larger than the signals of interest for the IR AOTF and
transmission spectrometers, respectively. Due to sunsafety constraints, all sky spectra are effectively out
of focus yielding an effective field of view of ~3º diameter. To obtain the desired sensitivities for O2 and
H2O vapor, we use ~20 minutes of total integration
time to provide multiple visits to each pointing position.
First results:
Initial results include several retrievals of water
vapor mixing ratios along with a tentative determination of CO abundances in a limited number of measurements. H2O was found to vary between 24 and 147
ppmv with a 5 ppmv uncertainty from H2O and CO2
infrared signatures, in rough agreement with previous

MEDA RH measurements [9].
CO mixing ratios range between 900 and 1700
ppmv, values which correspond well with concentrations observed from orbit, such as with the ACS instrument onboard the ExoMars Trace Gas Orbiter
[10].

Figure 1: Fitting attempt of CO, CO2 and H2O in the
IR. Data collected on Sol 111.
References:
[1] Wiens, R.C., et al. , 2021. Space Sci Rev 217, 4.
[2] Maurice, S., et al., 2021. Space Sci Rev 217, 47.
[3] Royer, C., et al.., 2020. Review of Scientific Instruments 91, 063105.
[4] Fouchet, T., et al., 2021, Icarus, 373, 114733.
[5] McConnochie T. H et al., 2018. Icarus 307, 294.
[6] Smith M. D. et al. (2018), Icarus 301, 117.
[7] Rodriguez-Manfredi et al. (2021) Space Sci Rev,
217, 3, 48.
[8] Trainer M. G. et al. (2019), JGR 124, 3000.
[9] Tamppari et al. (2021), AGU fall meeting, New
Orleans P251-2253.
[10] Fedorova et al. (2022), in prep.