What are our planet’s main carbon sinks: tropical rainforests or the oceans? How many tonnes of CO₂ are released by the world’s cities, vegetation and the oceans? As surprising as it may seem, we don't know how much CO₂ is absorbed and released in certain parts of the world, due to a scarcity of ground-based measuring stations. Nor do we know how these amounts vary with the seasons. Yet this type of information is crucial for understanding the causes and consequences of climate warming, as CO₂ is the most important greenhouse gas produced by human activity.

To fill in these gaps in our knowledge, NASA launched the OCO-2 satellite in 2014. In 2020, CNES will take over this role with the launch of MicroCarb. Its dispersive spectrometer instrument will be able to measure the total column concentration of CO₂ with a high degree of precision (on the order of 1 ppm) and with a pixel size of 5 km x 6 km.

The instrument will be flown on a microsatellite built around CNES’s Myriade spacecraft bus. This mission involves the French scientific community studying climatology and the carbon cycle.