The TanSat mission (also known as CarbonSat, Tan means "carbon" in Chinese), funded by MOST (Ministry of Science and Technology) of China, is the first Chinese minisatellite devoted to the monitoring and detection of carbon dioxide. The project was announced in 2010, within the Chinese National Program, but the official kick-off was in January 2011.

The satellite carries two scientific instruments: an Atmospheric Carbon-dioxide Grating Spectroradiometer and a Cloud Aerosol Polarization Imager.

The spectrometer is intended to detect the CO₂ near-infrared absorption (at 1.61 and 2.06 microns), and the O2 A-band within the reflected sunlight (at 0.76 microns, with 2*1 km2 of spatial resolution).

The Imager data are employed to compensate CO₂ measurement errors coming from cloud and aerosol. These measurements are acquired in high-resolution at 0.38, 0.67, 0.87, 1.38 and 1.64 microns. In addition, the Imager can also use polarimetric measurements (at 0.67 and 1.64 microns in multi polarization angles) to achieve detailed cloud and aerosol data.