TANGO The Twin Anthropogenic Greenhouse Gas Observers Mission

The Twin Anthropogenic Greenhouse Gas Observers (TANGO) mission is a small satellite mission to be launched in 2028, under the ESA Scout Programme tapping into NewSpace to quickly deliver affordable and innovative science, as part of ESA’s FutureEO Programme a schedule of three years from mission kick-off to launch. Designed to complement the Copernicus atmospheric monitoring missions Sentinel-5 Precursor, Sentinel‑4/5, and the CO2M carbon dioxide monitoring mission, TANGO will observe carbon dioxide and methane emissions from human activities to support verification of the Paris Agreement. The mission is anticipated to generate >10,000 emission estimates per year for major industrial facilities and power plants. The scientific community will be able to propose specific observation targets, which will be incorporated into mission planning alongside routine observations aimed at enhancing current state-of-the-art point-source emission inventories. Two agile CubeSat-class satellite buses, each carrying an imaging spectrometer, will operate in close formation with a temporal separation of less than 1 minute, enabling near-sequential observations of the same target area. Platform agility is ensured by three-axis stabilized reaction wheel control, which permits flexible spectrometer pointing with a roll capability of ±30° and forward motion compensation. This forward motion compensation increases the effective integration time by up to a factor of five, thereby enhancing spatial coverage and improving the precision of the retrieved geophysical quantities. As part of the mission implementation, a dedicated ground segment will be established to provide the scientific user community with open and freely accessible data products. These will include calibrated top-of-atmosphere radiance measurements (Level-1b), column-averaged dry air mole fractions of CO2 (XCO2) and CH4 (XCH4), as well as tropospheric NO2 column densities (Level-2), and corresponding emission estimates for CO2, CH4, and NO2 (Level-4). TANGO’s first satellite, TANGO-Carbon, will measure solar-reflected radiances in the 1.6 µm spectral region with a spectral resolution of 0.45 nm, enabling the detection of moderate to strong CH4 emissions (≥ 5 kt yr⁻¹) and CO2 emissions (≥ 2.5 Mt yr⁻¹). The TANGO-Nitro instrument will provide collocated NO2 observations derived from radiance measurements in the visible spectral range with a spectral resolution ≤ 0.6 nm, facilitating plume detection and the use of the CO2/NO2 ratio for improved source characterization and emission quantification. In this contribution, we describe the status of the TANGO mission, the planned data products, the associated scientific opportunities, and the mechanisms for engagement of the scientific community in data exploitation.