Europe's Mars orbiters: status & highlights

Mars Express (MEX), launched in 2003, remains a highly productive mission in its third decade of operation at Mars. Recent science highlights include (1) discovery of englacial (internal) folding of the South Polar Layered Deposits, providing evidence of ice flow; (2) study of large-scale ionospheric ‘holes’ (plasma depletion events); (3) continuing development of digital elevation models and mosaics from the HRSC imager. Many of the key outcomes of two decades of Mars Express have been summarised in an article collection in Space Science Reviews titled “Mars Express: Pioneering Two Decades of European Science and Exploration of Mars”.

ExoMars Trace Gas Orbiter (TGO), launched in 2016, has now completed over four complete Mars years of science observations since reaching its nominal Mars orbit in April 2018. Recent science highlights include (1) detailed characterisation of the spatial and temporal variation of atmospheric hydrogen chloride (HCl), and modelling to understand its sources and sinks; (2) study of Mars’ water cycle, in particular relating to the transport of water to high altitudes and subsequent escape; (3) Repeated imaging of dust devils, allowing determination of near-surface wind velocities; (4) continued monitoring of radiation doses throughout the mission, including the most energetic event recorded yet in May 2024.

Acknowledgments: This abstract represents the work of hundreds of researchers and engineers across the MEX and TGO science and operations teams. MEX and TGO data are freely and publically available at ESA’s Planetary Science Archive (https://psa.esa.int/).