Tropomi circulates in an orbit around earth at an altitude of 824 km, onboard the Sentinel-5 precursor satellite. From this position, it is perfectly capable of mapping the entire atmosphere on a daily basis, with details of 7×7 km. This high resolution makes it possible to detect air pollution down to city level.
Tropomi watches, it compares. With a few steps it detects light reflected by the atmosphere, comparing it to direct sunlight. The difference between both sources of light reveal significant information on how the atmosphere is made up.
From infrared to ultraviolet, Tropomi is capable of observing many different wavelengths. Light is reflected through mirrors, it is unravelled by gratings and ultimately captured with a detector. Due to Dutch innovations like immersed grating and freeform optics, this device is a lot better compared to previous ones.