ExoMars Trace Gas Orbiter

ExoMars 2016 / TGO

Agency

ESA / Roscosmos

Country

🇪🇺 Europe / Russia

Launched

2016-03-14

Status

Ongoing

Mass

3,732 kg

Instruments

4 science instruments

NOMAD spectrometer suite, ACS atmospheric chemistry suite, CaSSIS colour stereo camera, FREND neutron detector

Orbit

Near-circular polar science orbit, ~400 km altitude, 2-hour period

Key Findings

1.NOMAD and ACS instruments produced the most precise inventory of Martian trace gases to date, placing stringent upper limits on methane abundance (<0.05 ppb) — conflicting with earlier ESA/NASA detections and constraining possible biological or geological methane sources
2.FREND neutron detector found large near-surface hydrogen (water-ice) deposits at mid-latitudes down to ~1 m depth, significantly expanding the known water-ice map
3.Detected seasonal variations in chlorine compounds including HCl — the first detection of a halide gas in the Martian atmosphere, indicating active surface chemistry
4.CaSSIS camera captures 4.6 m/pixel colour stereo imagery, providing complementary landing-site characterisation and change detection

Mission Outcome

ExoMars TGO has operated in its science orbit since April 2018 and continues science operations as of 2026. Its definitive methane non-detection challenged previous mission results and constrains astrobiology models for Mars. The spacecraft serves as the primary relay for the ESA/Roscosmos Rosalind Franklin rover mission, planned for launch in 2028.

Sources

[1] ESA — retrieved 2026-06-01
“The Trace Gas Orbiter (TGO) is looking for signs of life on Mars and is setting up a communications relay for rovers and landers.”
[2] NASA NSSDCA — retrieved 2026-06-01

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