Upper Atmosphere Research Satellite between positions downrange, generally northeast of this position. Upper Atmosphere Research Satellite The Upper Atmosphere Research Satellite (UARS) was a NASA-operated orbital observatory whose mission was to study the Earth’s atmosphere, particularly the protective ozone layer. The satellite was deployed from Space Shuttle "Discovery" during the STS-48 mission on 15 September 1991. It entered Earth orbit at an operational altitude of , with an orbital inclination of 57 degrees. The original mission duration was to be only three years, but was extended several times. When the mission finally ended in June 2005 due to funding cuts, 14 years after the
Greenhouse and icehouse Earth of "scrubbing" of this carbon dioxide in the atmosphere, that the earth would return to a greenhouse state. Some scientists believe that the end of the snowball Earth caused an event known as the Cambrian Explosion, which produced the beginnings of multi-cellular life. However some biologists claim that a complete snowball Earth could not have happened since photosynthetic life would not have survived underneath many meters of ice without sunlight. However, it has been observed that, even under meters of thick ice around Antarctica, sunlight shows through. Most scientists today believe that a "hard" Snowball Earth, one completely covered by