Year: 2026
Type: article
Abstract: Transit spectroscopy is a powerful tool for probing atmospheric structures of exoplanets. Accurately accounting for the effects of aerosols is key to reconstructing atmospheric properties from transit spectra, yet this remains a significant challenge. To advance this effort, it is invaluable to examine the spectral features of well-characterized planetary atmospheres. Here, we synthesize empirical transit spectra of Mars across different seasons based on data from the NOMAD’s Solar Occultation channel on board ExoMars/TGO, which operates at wavelengths of 0.2–0.65 and 2–4 μ m. In the generated empirical transit spectra, the atmosphere below 25 km is found to be largely opaque due to the presence of micron-sized dust and H 2 O ice clouds, both of which substantially weaken spectral features. The spectra exhibit CO 2 absorption features at 2.7–2.8 μ m and signatures of submicron-sized mesospheric H 2 O ice clouds around 3.1 μ m, accompanied by a continuum slope. The amplitudes of these spectral features are found to vary with the Martian seasons, where the dust storms weaken the CO 2 signatures and strengthen the H 2 O ice features, which serve as potential indicators of a dusty planet like Mars. If TRAPPIST-1f possessed a Mars-like atmospheric structure, both CO 2 and H 2 O ice features would be detectable at a noise level of 3 ppm, a level likely beyond current observational capabilities. Nevertheless, the 3.1 μ m feature produced by submicron-sized mesospheric H 2 O ice clouds offers a novel avenue for characterizing the atmospheres of habitable-zone exoplanets.
Source: The Astronomical Journal
Institutions: Tohoku University, The University of Tokyo, The Graduate University for Advanced Studies, SOKENDAI, National Astronomical Observatory of Japan, Kyoto Sangyo University, Goddard Space Flight Center, Royal Belgian Institute for Space Aeronomy, Instituto de Astrofísica de Andalucía, The Open University, Institute for Space Astrophysics and Planetology
Language: English
Subfield: Astronomy and Astrophysics
Field: Physics and Astronomy
Domain: Physical Sciences
SDG: Climate action
Open Access status: gold
Estimated APC paid: $4,499
Funders: National Aeronautics and Space Administration, Ministerio de Ciencia, Innovación y Universidades, Belgian Federal Science Policy Office, Ministerio de Ciencia e Innovación, Instituto de Astrofísica de Andalucía, Goddard Space Flight Center, Japan Society for the Promotion of Science, Agencia Estatal de Investigación
Awards: G1105844351, G1171257612, G121809054, G1255157662, G1274262131, New isotope obervations of Mars atmsopheric evolution: International collaboration of European and Japanese Mars exploration missions, G1381791653, G15476951, G1650125035, G1855990336, G2009272473, G2233982916, G2262748287, Evolution of carbon and nitrogen and generation of prebiotic molecules in the Martian atmosphere, G2309174360, G2372423146, G2548895409, G2660406951, G3126048175, G3469697278, G3480869486, G3518538256, G3696727022, G373897614, G4212894969, G425668148, G430777504, 探査機・望遠鏡観測による火星の鉛直水輸送過程解明, G463062595, G490073602, G491712853, G5143080163, Water transport through clouds: development of non-equilibrium planetary cloud physics, G526084217, G5387677895, G5421974903, G5635532810, G5818204694, G5894067328, G6207345472, G6643721397, G6728930308, G6968665035, G7084143925, 古代説話における諸寺縁起の研究, G7742527132, G7805626310, G7863371703, G8181105605, G8304717208, G8497050386, Climates and spectral signatures of rocky planets around low-mass stars, G8920660035, 義歯床用強化プラスチックスの材料力学的研究, G99296377
OpenAlex ID: W7129564653