Ten years after its arrival at Mars, the European Space Agency's ExoMars Trace Gas Orbiter (TGO) has expanded its role far beyond the original plan to study trace gases and relay communications for surface missions.

The spacecraft entered Mars orbit on 19 October 2016 at 15:24 UTC, following a successful engine burn that slowed the vehicle for capture by Martian gravity. At the same time, the Schiaparelli Entry, Descent and Landing Demonstrator Module began its descent, returning engineering data until a software issue caused premature engine shutdown, leading to a crash landing. The data from Schiaparelli contributed to design refinements for the Rosalind Franklin rover.

Silvia Sangiorgi, head of the Mars exploration missions operations unit, described the arrival as a moment of "much lighter" relief after three days of intensive preparations. The spacecraft fired its engines at 13:05 UTC, relayed signals from Schiaparelli during atmospheric entry, and then disappeared behind Mars during the burn. Telemetry confirmed successful orbital insertion, after which the mission entered a year-long aerobraking phase to adjust its orbit for scientific operations.

From an altitude of approximately 400 kilometers, TGO has used its high-sensitivity instruments to analyze the Martian atmosphere. Project scientist Colin Wilson noted that the orbiter was designed to detect trace gases at a level of precision unmatched by any mission in recent generations. Its observations have included the first detection of hydrogen chloride in the Martian atmosphere, measurements of water loss that inform models of past habitability, and continued monitoring of methane, a gas previously reported but not yet confirmed by TGO.

The orbiter’s imaging system has mapped over 10% of Mars' surface in four color bands, supporting scientific analysis and landing site assessments for the ExoMars rover. Additional instruments have measured radiation levels and identified subsurface water ice deposits, data that are relevant to planning future human exploration.

TGO has also demonstrated evolving capabilities in communications and operations. Spacecraft operations manager Peter Schmitz explained that the orbiter has adapted to challenges such as solar conjunctions, during which it stores surface-collected data for later transmission when Earth communications are interrupted. In 2024, updated flight software was uploaded to reduce gyroscope usage, extending their lifespan in preparation for the arrival of the Rosalind Franklin rover.

The mission’s development has relied on iterative learning and team expertise. Schmitz emphasized that operational decisions are made by a team capable of balancing spacecraft constraints with mission priorities, a process that has reinforced the importance of trust in engineering judgment.

Jorge Vago, ExoMars project scientist, highlighted the broader significance of accumulated experience across European planetary missions. He noted that the knowledge gained from TGO’s longevity and operational adaptations provides a foundation for future exploration initiatives, reflecting a sustained vision supported by scientific, technological, and industrial collaboration.

As the mission approaches its second decade, its contributions continue to inform both scientific understanding and operational strategies for Mars exploration.