Look into the eyes…otopes: a guide to interpret the history of terrestrial planets.

The isotopic composition of a planet's key constituents provides valuable insights into its evolutionary history. However, these measurements are influenced by various processes, including surface interactions, atmospheric fractionation, and escape mechanisms, which must be carefully considered for accurate interpretation. Bulk isotopic abundances reveal long-term evolution, while localized and time-resolved measurements shed light on active processes, such as photochemical reactions, that can simultaneously affect multiple species.

Recent isotopic measurements on Mars—spanning hydrogen, carbon, and other elements—offer a wealth of information but also present challenges, with discrepancies in absolute values and variability between instruments and datasets. Understanding these measurements in the context of Earth's isotopic record enhances our ability to draw comparative insights into planetary evolution.

This talk will survey recent findings on isotopic abundances of key species such as H2O, CO2, CO, and organics on Mars and Earth, considering both surface and atmospheric data. For Mars, we will focus on heterogeneous measurements from multiple instruments, including MSL, TGO-NOMAD, TGO-ACS, and MEx-SPICAM. By comparing these datasets across the two planets, we aim to highlight their significance within a framework of comparative planetology and explore the processes shaping their past and present states.