Ares: A Mars model retrieval framework for ExoMars Trace Gas Orbiter NOMAD solar occultation measurements

Ares is an extension of the TauREx 3 retrieval framework for the Martian atmosphere. Ares is a collection of new atmospheric parameters and forward models, designed for the European Space Agency's (ESA) Trace Gas Orbiter (TGO) Nadir and Occultation for MArs Discovery (NOMAD) instrument, Solar Occultation (SO) channel. Ares provides unique insights into the chemical composition of the Martian atmosphere by applying methods utilised in exoplanetary atmospheric retrievals, Waldmann et al. (2015), Al-Refaie et al. (2019). This insight may help unravel the true nature of $CH_{4}$ on Mars. The Ares model is here described. Subsequently, the components of Ares are defined, including; the NOMAD SO channel instrument function model, Martian atmospheric molecular absorption cross-sections, geometry models, and a NOMAD noise model. Ares atmospheric priors and forward models are presented, (i.e., simulated NOMAD observations), and are analysed, compared and validated against the Planetary Spectrum Generator, Villanueva et al. (2018).

[1]  G. Tinetti,et al.  TauREx 3: A Fast, Dynamic, and Extendable Framework for Retrievals , 2019, 1912.07759.

[2]  M. Lepère,et al.  CO2-broadening coefficients in the ν3 fundamental band of methane , 2019, Journal of Molecular Spectroscopy.

[3]  Alejandro Cardesín-Moinelo,et al.  Independent confirmation of a methane spike on Mars and a source region east of Gale Crater , 2019, Nature Geoscience.

[4]  Manish R. Patel,et al.  No detection of methane on Mars from early ExoMars Trace Gas Orbiter observations , 2019, Nature.

[5]  Manish R. Patel,et al.  Methane on Mars: New insights into the sensitivity of CH4 with the NOMAD/ExoMars spectrometer through its first in-flight calibration , 2018, Icarus.

[6]  J. Worden,et al.  Methane on Mars and Habitability: Challenges and Responses , 2018, Astrobiology.

[7]  David J. Smith,et al.  Venus' Spectral Signatures and the Potential for Life in the Clouds , 2018, Astrobiology.

[8]  C. McKay,et al.  Background levels of methane in Mars’ atmosphere show strong seasonal variations , 2018, Science.

[9]  Michael D. Smith,et al.  Planetary Spectrum Generator: An accurate online radiative transfer suite for atmospheres, comets, small bodies and exoplanets , 2018, Journal of Quantitative Spectroscopy and Radiative Transfer.

[10]  J. Tennyson,et al.  EXOCROSS: a general program for generating spectra from molecular line lists , 2018, Astronomy & Astrophysics.

[11]  Daniel Foreman-Mackey,et al.  corner.py: Scatterplot matrices in Python , 2016, J. Open Source Softw..

[12]  Ian Thomas,et al.  Expected performances of the NOMAD/ExoMars instrument , 2016 .

[13]  I R Thomas,et al.  Optical and radiometric models of the NOMAD instrument part II: the infrared channels - SO and LNO. , 2016, Optics express.

[14]  J. C. McConnell,et al.  Science objectives and performances of NOMAD, a spectrometer suite for the ExoMars TGO mission , 2015 .

[15]  Javier Cubas,et al.  NOMAD spectrometer on the ExoMars trace gas orbiter mission: part 1--design, manufacturing and testing of the infrared channels. , 2015, Applied optics.

[16]  Andrew Steele,et al.  Mars methane detection and variability at Gale crater , 2015, Science.

[17]  Jonathan Tennyson,et al.  TAU-REX I: A NEXT GENERATION RETRIEVAL CODE FOR EXOPLANETARY ATMOSPHERES , 2014, 1409.2312.

[18]  K. Heng,et al.  ATMOSPHERIC RETRIEVAL ANALYSIS OF THE DIRECTLY IMAGED EXOPLANET HR 8799b , 2013, 1307.1404.

[19]  Charles F. F. Karney.  Algorithms for geodesics , 2011, Journal of Geodesy.

[20]  Andrew Gelman,et al.  Handbook of Markov Chain Monte Carlo , 2011 .

[21]  P. Drossart,et al.  Titan solar occultation observed by Cassini/VIMS: Gas absorption and constraints on aerosol composition , 2009 .

[22]  Michael D. Smith,et al.  Strong Release of Methane on Mars in Northern Summer 2003 , 2009, Science.

[23]  F. Feroz,et al.  MultiNest: an efficient and robust Bayesian inference tool for cosmology and particle physics , 2008, 0809.3437.

[24]  S. Calcutt,et al.  The NEMESIS planetary atmosphere radiative transfer and retrieval tool , 2008 .

[25]  C. Bohren,et al.  Appendix A: Homogeneous Sphere , 2007 .

[26]  Daria Morozova,et al.  Survival of Methanogenic Archaea from Siberian Permafrost under Simulated Martian Thermal Conditions , 2007, Origins of Life and Evolution of Biospheres.

[27]  Heikki Haario,et al.  DRAM: Efficient adaptive MCMC , 2006, Stat. Comput..

[28]  J. Skilling.  Nested sampling for general Bayesian computation , 2006 .

[29]  Barbara Sherwood Lollar,et al.  Is Mars alive , 2006 .

[30]  Michel Kruglanski,et al.  MODELING AND RETRIEVAL OF ATMOSPHERIC SPECTRA USING ASIMUT , 2006 .

[31]  Gang Li,et al.  The HITRAN 2008 molecular spectroscopic database , 2005 .

[32]  Marco Giuranna,et al.  Detection of Methane in the Atmosphere of Mars , 2004, Science.

[33]  Tobias Owen,et al.  Detection of methane in the martian atmosphere: evidence for life? , 2004 .

[34]  Frank G. Lemoine,et al.  An improved solution of the gravity field of Mars (GMM‐2B) from Mars Global Surveyor , 2001 .

[35]  Clive D Rodgers,et al.  Inverse Methods for Atmospheric Sounding: Theory and Practice , 2000 .

[36]  Stephen R. Lewis,et al.  Improved general circulation models of the Martian atmosphere from the surface to above 80 km , 1999 .

[37]  W. K. Hastings,et al.  Monte Carlo Sampling Methods Using Markov Chains and Their Applications , 1970 .

[38]  N. Metropolis,et al.  Equation of State Calculations by Fast Computing Machines , 1953, Resonance.

[39]  E. R. Polovtseva,et al.  The HITRAN2012 molecular spectroscopic database , 2013 .

[40]  Angioletta Coradini,et al.  PFS: A fourier spectrometer for the study of Martian atmosphere , 1997 .