SAGE III on ISS role in climate processes. water vapor measurements will provide important contributions on the long-term effect of this green house gas. Ozone research has remained at the forefront of atmospheric science for many years because stratospheric ozone shields the Earth's surface (and its inhabitants) from harmful ultraviolet radiation. Since recent declines in stratospheric ozone have been linked to human activity, accurate long-term measurements of ozone remain crucial. It is important to monitor ozone levels in the lower stratosphere and upper troposphere since observed trends are the largest and most poorly understood at those altitudes. SAGE III's high vertical resolution and long-term
Ultraviolet astronomy provide essential information about the evolution of galaxies. The ultraviolet universe looks quite different from the familiar stars and galaxies seen in visible light. Most stars are actually relatively cool objects emitting much of their electromagnetic radiation in the visible or near-infrared part of the spectrum. Ultraviolet radiation is the signature of hotter objects, typically in the early and late stages of their evolution. In the Earth's sky seen in ultraviolet light, most stars would fade in prominence. Some very young massive stars and some very old stars and galaxies, growing hotter and producing higher-energy radiation near their birth or