Stratosphere Stratosphere The stratosphere () is the second major layer of Earth's atmosphere, just above the troposphere, and below the mesosphere. The stratosphere is stratified in temperature, with warmer layers higher and cooler layers closer to the Earth; this increase of temperature with altitude is a result of the absorption of the Sun's ultraviolet radiation by the ozone layer. This is in contrast to the troposphere, near the Earth's surface, where temperature decreases with altitude. The border between the troposphere and stratosphere, the tropopause, marks where this temperature inversion begins. Near the equator, the stratosphere starts at as high as ,
Exposing Microorganisms in the Stratosphere Exposing Microorganisms in the Stratosphere Exposing Microorganisms in the Stratosphere (E-MIST) is a NASA study to determine if a specific microorganism could survive conditions like those on the planet Mars. The study transported "Bacillus pumilus" bacteria and their spores by helium-filled balloon to the stratosphere of Earth (~31 km above sea level) and monitored the ability of the microorganisms to survive in extreme Martian-like conditions such as low pressure, dryness, cold, and ionizing radiation. A test flight of the balloon and gondola was launched from New Mexico on 24 August 2014. A second, longer flight, took place on 10 October