A view of the ATMOS (Atmospheric Trace Molecule Spectroscopy Experiment)
instrument in the bay of the NASA Space Shuttle during its ATLAS I (Atmospheric
Laboratory for Applications and Science) mission during late March/early April
1992 (shuttle mission STS-45). The ATMOS instrument is the white box just behind the second black
sphere on the left. Data from the four flights of ATMOS on the space-
shuttle between 1985 and 1994 continue to be analyzed. Many scientific papers on the chemistry and transport of stratospheric ozone have resulted from these flights, including those in the special section of Volume 23 of the journal Geophysical Research Letters devoted to the ATLAS missions. Currently the ATMOS measurements are being retrieved using a new algorithm that extends the retrieval of atmospheric measurements to tropospheric altitudes.
The ATMOS instrument collects data using a technique called solar occultation. The transmission of sun light through the atmosphere is measured at very precise wavelengths during sunset and sunrise. By obtaining a series of transmission spectra as the sun grazes the atmosphere at different altitudes during its rise or set, scientists can infer concentration profiles for dozens of molecules. The following picture shows a sunrise as seen by the astronauts from the space shuttle during one of the ATMOS missions. The curvature of the earth is evident as the sun rises above a convective cloud system in the troposphere.
