The depletion of stratospheric ozone and the changes in the global climate system are examples of environmental problems that have the potential to affect the Earth's habitability for generations. In order to understand how these changes will affect the coupled atmosphere-ocean-land systems, NASA has built a series of research and monitoring systems that use satellites, aircraft, balloons and ground-based instruments. At Table Mountain Facility (TMF) our group has built two spectrometers for the remote measurement of atmospheric composition:
Fourier Transform Ultraviolet Spectrometer (FTUVS) is a high resolution interferometric spectrometer for the measurement of atmospheric molecules with resolved spectral features in the 290-800 nm spectral region. This instrument uses the Sun or Moon as a light source, and measures the absorption spectra of molecules such as OH (hydroxyl), NO2 (nitrogen dioxide), NO3 (nitrate radical) and BrO (bromine monoxide) to obtain vertical column abundances.
Grating Spectograph is a medium resolution grating spectrometer which employs a 1024 element diode array detector. This instrument can be used in the solar/lunar absorption modes, and also in a sky-viewing mode to detect light that has been scattered by high-altitude air molecules. This instrument is used for measurements of NO3 (nitrate radical), NO2 (nitrogen dioxide), O3 (ozone) and other molecules.
Layout of the FTUVS facility showing the tracker (heliostat), telescope and FTUVS interferometer.
The FTUVS heliostat showing the 20 in. primary mirror and the 12.6 in. secondary mirror. The secondary can be easily removed from its mounting for zenith sky observations.
View of the FTUVS interferometer (inside the large white box) and the telescope. The telescope achieves a 3:1 magnification of the solar image and has a CCD camera for fine tracking which views the solar image reflected off the field stop.