George Cann
Abstract:
We explore the Martian atmosphere with Ares; an extension of the TauREx3 exoplanetary atmospheric retrieval framework for the Martian atmosphere, designed for interpreting the European Space Agency's (ESA) Trace Gas Orbiter (TGO) Nadir and Occultation for MArs Discovery (NOMAD) instrument, Solar Occultation (SO) channel measurements. Ares provides novel insights into the 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 methane (CH4) on Mars, through producing marginalised and conditional posterior distributions of Ares forward model parameters, which can in turn be used to map correlations between these parameters.
Here we describe the Ares model and subsequently define its components, through a set of annotated diagrams. Firstly, we show a flow diagram of the Ares model including; NOMAD SO channel instrument function models, geometry models and Mars Climate Database (MCD) atmospheric priors. Secondly, we show a diagram of Ares marginalised and conditional posterior distributions of publicly available ESA Planetary Science Archive (PSA) NOMAD SO Channel solar occultation data (PDS4 - Calibrated Level 3 - XML/TAB) as a function of tangent height.
Acknowledgements:
We would like to thank the UK Space Agency for their support of this Aurora Science studentship STFC:535385. The development of TauREx has received funding from the European Research Council (ERC) under the European Union’s Horizon 2020 Research and Innovation Programme (Grant agreement No. Meteoritics892, ExoAI).
Read time: 1 minute.
Slide question: Is there life on Mars?
Description: This slide contains three boxes. The first top section includes the title “Exploring the Martian atmosphere with Ares” and contact details of the co-authors. The first author of the poster is George Cann. The second box, found in the bottom left, is titled “1. Is there life on Mars?”. The second box, highlights in red the detection of methane on Mars and that both biological and non-biological could explain the detection. The third box, found in the bottom right is of the detection of methane on Mars at Northern mid-summer in 2003, this is adapted from Mumma et al. (2009).
Slide 2: An introduction to Ares, a Mars extension of TauREx3.
Read time: 1 minute.
Slide question: What is Ares?
Description: This slide contains two boxes. The first top section includes the title “Ares is an extension of the TauREx3 exoplanetary atmospheric retrieval framework for Mars for ESA’s TGO NOMAD SO channel.” The first box, highlights in red how Ares may help unravel the nature of CH4 on Mars, because of its ability to generate posterior distributions. The second box, is a flow diagram of the Ares model. Flow diagram boxes for Mars Chemistry, Temperature, Planet, Star, Geometry and HITRAN 2016 all lead to the central box for the Ares Forward Model. All of the aforementioned components are required in the Forward Model. The Ares Forward Model performs radiative transfer calculations in order to simulate NOMAD spectra. Flowing from the Forward Model box is a box for the NOMAD Instrument function, these instrument functions are applied to the simulated spectra. To the right of the part of the flow diagram that focuses on simulating NOMAD spectra, is a flow diagram boxes corresponding to real measured NOMAD spectra. Through inverting real measured spectra with simulated spectra, determination of the trace gases concentrations that resulted in the observed spectra can be observed. The final output of the Ares model is a box labelled Output, a white arrow highlights that the main output is a set of posterior distributions.
Slide 3: Ares Posterior Distributions as a function of Tangent Height
Read time: 2 minutes.
Description: This slide contains two boxes. The first top box contains a diagram of Ares posterior distributions as a function of tangent height, with corresponding TGO measurements, LOS and Mars atmospheric layers. These posterior distributions show regions of high and low probability density of a particular atmospheric parameter having a particular value. These distributions enable correlations between these atmospheric parameters (e.g. such as temperature and CH4 concentration) to be determined. The second bottom box explains the above diagram.
Slide 4: Acknowledgements, Conclusions, References, Further Information.
Read time: 2 minutes.
Slide questions: Where can I find further information? How can I contact you? What was shown? What are your references? Who are you acknowledging?
Description: This slide contains four boxes. The first top left section includes the title “Summary”. The first box, highlights in red the future search with Ares for search for CH4 and to search for possible signals of its derivatives, namely methanol, CH3OH, and formaldehyde, H2CO. The bottom left box is titled “Acknowledgements”, the funders of this research are the UK Space Agency and the European Research Council. The top right box is titled “References”, with 12 references shown below. The final box is titled “Further Information”, details on contacting the author are shown here, the primary means of contact is via email at george.cann.15@ucl.ac.uk. Further links on Ares are also highlighted.