MicroCarb is a mission dedicated to the study of the greenhouse gas, and more particularly to Carbon dioxide (CO₂). The measurement of the Carbon flux on the surface, meaning the exchanges between the different Carbon reservoirs that are the atmosphere, the ocean, the vegetation and "fossil" Carbon (coal, gas, oil) is one of the scientific community priority faced with announced global or regional climate changes.

A spatial measurement of atmospheric CO₂ could bring the measurement density needed to know the carbon budget of areas with nearly no measurement stations, such as Amazon, Africa and Boreal regions. These regions are vulnerable to climate changes, and GIEC (Groupe d'Experts Intergouvernemental sur l'Evolution du Climat) models are forecasting CO₂ loss by vegetation and grounds in the future.

CNES in close collaboration with LSCE has thus begun a phase A study for the MicroCarb project which objective is to measure the carbon dioxide (CO₂) atmospheric column on the whole world with precision sufficient to enable the retrieval of continental and oceanic surface flux.

One of this Phase A objectives is to select the best instrument concept (scattering grating spectrometer or static Fourier Transform interferometer) filling the mission requirement.

The Japanese mission GOSAT launched in February 2009 by JAXA is the first mission dedicated to the evaluation of the Carbon flux. NASA prepared the launch of OCO2 mission before 2013. With a launch forecast in 2018, MicroCarb will bring a European contribution to this set of Carbon flux measurements from space and could be a precursor for an operational series.