The Upper Atmosphere Research Satellite (UARS) is an orbital observatory whose mission was to study the Earth’s atmosphere, particularly the protective ozone layer. The 5,900-kilogram satellite was deployed from Space Shuttle Discovery during the STS-48 mission in September 1991. UARS entered orbit on 15 September 1991 at an operational altitude of 600 kilometers, with an orbital inclination of 57 degrees.

The original mission duration was to be only three years, but in June 2005, 14 years after the satellite's launch, six of its ten instruments were still operational. The George W. Bush administration reduced funding for the Earth Science Enterprise, but increased concerns for ozone depletion in the scientific community made the de-commissioning of UARS controversial.

Read More at: NASA and the Environment, The case for ozone Depletion