Europe is set to launch a satellite on 13 October dedicated to monitoring Earth's atmosphere, the protective layer that shields the planet from the sun's radiation, the European Space Agency said.
The Sentinel-5P orbiter will form part of Europe's Copernicus Earth monitoring project to track environmental damage and aid disaster relief operations.
It will contribute to warnings about eruptions of volcanic ash that can threaten aviation safety, and high levels of air pollution or skin-damaging UV radiation, the agency said.
"In addition, the measurements will improve our knowledge of important processes in the atmosphere related to the climate and to the formation of holes in the ozone layer," it said.
The satellite has a special instrument to map concentrations of gases that affect the air we breathe and the climate.
Launch is set for 0927 GMT on Friday from the Plesetsk Cosmodrome in northern Russia, and a final rehearsal was successfully concluded on Tuesday, the ESA said.
This will be the sixth satellite to join the Copernicus constellation. Others, launched since April 2014, monitor forest cover, and land and water pollution.
The programme is named for the 16th-century Polish astronomer who determined that the Earth orbited the sun, and not the other way round as convention had it at the time.
By mapping areas stricken by flood or earthquake, Copernicus will also help emergency teams identify worst-hit areas and locate passable roads, rail lines and bridges.