Fully Coupled Photochemistry of the Deuterated Ionosphere of Mars and Its Effects on Escape of H and D

Journal of Geophysical Research Planets American Geophysical Union (AGU) 128:7 (2023)

Authors:

Eryn Cangi, Michael Chaffin, Roger Yelle, Bethan Gregory, Justin Deighan

Spitzer IRS Observations of Titan as a Precursor to JWST MIRI Observations

PLANETARY SCIENCE JOURNAL American Astronomical Society 4:6 (2023) ARTN 114

Authors:

Brandon Park Coy, Conor A Nixon, Naomi Rowe-Gurney, Richard Achterberg, Nicholas A Lombardo, Leigh N Fletcher, Patrick Irwin

Abstract:

<jats:title>Abstract</jats:title> <jats:p>In this work, we present for the first time infrared spectra of Titan from the Spitzer Space Telescope (2004–2009). The data are from both the short wavelength–low resolution (SL; 5.13–14.29 <jats:italic>μ</jats:italic>m, <jats:italic>R</jats:italic> ∼ 60–127) and short wavelength–high resolution (SH; 9.89–19.51 <jats:italic>μ</jats:italic>m, <jats:italic>R</jats:italic> ∼ 600) channels showing the emissions of CH<jats:sub>4</jats:sub>, C<jats:sub>2</jats:sub>H<jats:sub>2</jats:sub>, C<jats:sub>2</jats:sub>H<jats:sub>4</jats:sub>, C<jats:sub>2</jats:sub>H<jats:sub>6</jats:sub>, C<jats:sub>3</jats:sub>H<jats:sub>4</jats:sub>, C<jats:sub>3</jats:sub>H<jats:sub>6</jats:sub>, C<jats:sub>3</jats:sub>H<jats:sub>8</jats:sub>, C<jats:sub>4</jats:sub>H<jats:sub>2</jats:sub>, HCN, HC<jats:sub>3</jats:sub>N, and CO<jats:sub>2</jats:sub>. We compare the results obtained for Titan from Spitzer to those of the Cassini Composite Infrared Spectrometer (CIRS) for the same time period, focusing on the 16.35–19.35 <jats:italic>μ</jats:italic>m wavelength range observed by the SH channel but impacted by higher noise levels in the CIRS observations. We use the SH data to provide estimated haze extinction cross sections for the 16.67–17.54 <jats:italic>μ</jats:italic>m range that are missing in previous studies. We conclude by identifying spectral features in the 16.35–19.35 <jats:italic>μ</jats:italic>m wavelength range that could be analyzed further through upcoming James Webb Space Telescope Cycle 1 observations with the Mid-Infrared Instrument (5.0–28.3 <jats:italic>μ</jats:italic>m, <jats:italic>R</jats:italic> ∼ 1500–3500). We also highlight gaps in the current spectroscopic knowledge of molecular bands, including candidate trace species such as C<jats:sub>60</jats:sub> and detected trace species such as C<jats:sub>3</jats:sub>H<jats:sub>6</jats:sub>, that could be addressed by theoretical and laboratory study.</jats:p>

Miniaturized Radiometer for an Ice Giants mission for haze and cloud characterization

Copernicus Publications (2023)

Authors:

Víctor Apéstigue, Daniel Toledo, Ignacio Arruego, Patrick Irwin, Pascal Rannou, Alejandro Gonzalo, Juan José Jiménez, Javier Martínez-Oter, Margarita Yela, Mar Sorribas, Eduardo Sebastian

Uranus from JWST: First Results

Copernicus Publications (2023)

Authors:

Michael Roman, Leigh Fletcher, Heidi Hammel, Henrik Melin, Naomi Rowe-Gurney, Jake Harkett, Oliver King, Stefanie Milam, Glenn Orton, Patrick Irwin, Julianne Moses, Imke De Pater, Laurent Lamy

Photochemical depletion of heavy CO isotopes in the Martian atmosphere

Nature Astronomy Springer Nature 7:7 (2023) 867-876

Authors:

Juan Alday, Alexander Trokhimovskiy, Manish R Patel, Anna A Fedorova, Franck Lefevre, Franck Montmessin, James A Holmes, Kylash Rajendran, Jon P Mason, Kevin S Olsen, Denis A Belyaev, Oleg Korablev, Lucio Baggio, Andrey Patrakeev, Alexey Shakun

Abstract:

The atmosphere of Mars is enriched in heavy isotopes with respect to Earth as a result of the escape of the atmosphere to space over billions of years. Estimating this enrichment requires a rigorous understanding of all atmospheric processes that contribute to the evolution of isotopic ratios between the lower and upper atmosphere, where escape processes take place. We combine measurements of CO vertical profiles obtained by the Atmospheric Chemistry Suite on board the ExoMars Trace Gas Orbiter with the predictions of a photochemical model and find evidence of a process of photochemistry-induced fractionation that depletes the heavy isotopes of C and O in CO (δ13C = −160 ± 90‰ and δ18O = −20 ± 110‰). In the upper atmosphere, accounting for this process reduces the escape fractionation factor by ~25%, suggesting that less C has escaped from the atmosphere of Mars than previously thought. In the lower atmosphere, incorporation of this 13C-depleted CO fractionation into the surface could support the abiotic origin of recently found Martian organics.