In July 2025, construction started on TANGO, an extraordinary pair of satellites. In a few years, they will be tracking sources of greenhouse gases on Earth from space.
It takes two to tango. In late June, the contract for the construction of TANGO was signed between the European Space Agency ESA and main contractor ISISPACE. So this week, construction started already.
Rubbish dumps and factories
TANGO stands for Twin ANthropogenic Greenhouse gas Observers. The name describes what it is: a pair of similar satellites observing man-made greenhouse gases, such as emissions from power plants, landfills and factories.
Emission plumes
Each of the two compact, manoeuvrable cubesats has a capacity of 16 litres, and weighs 25 kilograms. One will soon measureCO2 and methane emissions - the main greenhouse gases - and the other nitrogen dioxide.
Both satellites carry instruments, built by TNO, that scan the Earth's surface, so-called push bromine spectrometers, says SRON's Jochen Landgraf. 'NO2 you measure in the visible part of the spectrum, between 405 and 490 nanometres.CO2 and methane precisely in the short-wave infrared region (SWIR) between 1590 and 1680 nanometres. So we use different cameras and some other optical components. The SWIR camera SRON is building specifically for TANGO.'
The two fly after each other. They take images of emission plumes with a resolution of 300 x 300 metres. Thus, every four days, the pair measures emissions from 150 to 300 large, industrial facilities and power plants. Per year, TANGO measures emissions from more than ten thousand sources.
Tripomi
The satellite pair complements Sentinel-5p, which with instrument Tropomi has already been measuring methane, among others, with a wider field of view since 2017, and the upcoming CO2M mission, which does so forCO2. 'Sees' Tropomi only 5 per cent of greenhouse gas sources, TANGO cranks that up to 70 per cent
Maintaining agreements
Finding sources of greenhouse gases is key to slowing down climate change. Many countries have promised to reduce their greenhouse gas emissions, in, for example, the Paris Climate Agreement and the Global Methane Pledge. To enforce those agreements, it is important to see exactly where greenhouse gases come from. If a company leaks methane, for example, it can be held accountable for this to plug the leaks.
'The TANGO data are of great value internationally because they are actionable, they are going to help take targeted measures,' says Richard Engelen, deputy director of the Copernicus Atmospheric Monitoring System (CAMS) of the European weather service ECMWF in a press release from the Netherlands Space Office.
Mega garbage dumps
A big story in The Engineer of August 2023 covered the biggest sources of methane emissions: livestock farming (cows' burps and farts are notorious) and oil and gas plants that malfunction. But particularly surprising were mega-waste dumps in poorer countries where large amounts of methane are released by decaying organic waste.
Four cooperating Dutch parties
TANGO will be owned by the European Space Agency (ESA). The satellite system is now being developed by four collaborating Dutch parties: the Delft-based company ISISPACE, TNO, SRON in Leiden and KNMI.
ISISPACE is leading the implementation and is responsible for the satellites, launch and operations of the two satellites. TNO develops and builds the instruments providing measurements ofCO2, methane and NO2 and is working on an emissions atlas for greenhouse gas emissions. SRON and KNMI are the scientific leaders of the project and are developing the algorithms to derive the gas concentrations. SRON is developing the electronics of the detectors and the ground segment for processing the data.
Update 15 July: added details on the two satellites.
Opening image: still image from an animation of TANGO. Images: SRON
