2025/09/19 by N. Thomas, Miguel Almeida, Omar Mokhtari +7 · 1 voice
Physics and Astronomy · #Planetary Science and Exploration #Space Science and Extraterrestrial Life #Space exploration and regulation
paper · pdf · doi:10.1126/sciadv.adu0859
openalex publication_date 2025/09/19 · openalex created_date 2025/10/10 · openalex updated_date 2026/06/15
We report on observations of the atmosphere above the limb of Mars in forward scattering geometry (~174° phase angle) using the Colour and Stereo Surface Imaging System (CaSSIS) aboard the European Space Agency’s ExoMars Trace Gas Orbiter spacecraft. These unique observations provide high-resolution (18 meters per pixel) measurements of light scattered by aerosols in the atmosphere. The observations are characterized by subkilometer-scale layering, ±20% variations in color of the individual layers, and high radiance ( I / F > 1). Strong spatial (latitudinal) variability is also evident, suggesting highly inhomogeneous absorption and atmospheric heating. Models of the radiance, while likely to be degenerate, indicate good agreement with lower-resolution results inferred from other techniques. Mesospheric aerosol layers (strongly blue in CaSSIS color ratios) are also evident. The observed decrease in the CaSSIS RED/BLU color ratio with altitude is indicative of a decrease in particle radius.