SAGE III INSTRUMENT

The SAGE III instrument is a grating spectrometer that measures ultraviolet/visible energy. It relies upon the flight-proven designs used in the Stratospheric Aerosol Measurement (SAM I) and first and second SAGE instruments.

SPECIFICATIONS Weight 76 kg Power 80 W on-orbit average Data Rate 115 Kbit/s Dimension 73 cm x 45 cm x 93 cm

The new SAGE III design incorporates Charge Coupled Device (CCD) array detectors and a 16 bit A/D converter.

Combined, these devices allow for wavelength calibration, a self-consistent determination of the viewing geometry, lunar occultation measurements, and expanded wavelength coverage.

SAGE III sensor assembly is illustrated below and consists of pointing and imaging subsystems and a UV/visible spectrometer.

The pointing and imaging systems are employed to acquire light from either the Sun or Moon by vertically scanning across the object.

The spectrometer uses an 800 element CCD linear array to provide continuous spectral coverage between 290 and 1030 nm. Additional aerosol information is provided by a discrete photodiode at 1550 nm.

This configuration enables SAGE III to make multiple measurements of absorption features of target gaseous species and multi-wavelength measurements of broadband extinction by aerosols.

The SAGE III instrument was developed and managed by NASA Langley Research Center and was built by Ball Aerospace in Boulder, CO. Three copies were produced. One instrument is mounted on the Meteor-3M spacecraft and a second was to be placed in orbit on the International Space Station.