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LITE Instrument

The LITE instrument was carried in the Shuttle cargo bay on a standard Spacelab pallet. The instrument was mounted on an orthogrid platform attached to the pallet by 52 struts. The orthogrid is a support platform for the instrument subsystems and was designed to be immune to thermal deformations which could affect optical alignment. A description of the major LITE subsystems follows.

Receiver Assembly

The receiver includes a one meter telescope and an aft-optics package. The telescope collects laser light scattered from the atmosphere, and brings it to focus in the aft optics. The aft optics includes wavelength selective optics to separate the return signal into its three color components. The 532 nm and 355 nm detectors are photomultiplier tubes, while the 1064 nm detector is a silicon avalanche photodiode.

Boresight Assembly

The boresight assembly consists of a two-axis motor-driven prism. Its purpose is to align the laser beam to the telescope field-of-view so that both point to the same column of atmosphere.

Laser Transmitter Module (LTM)

The LTM consists of two flash lamp-pumped, Q-switched Neodymium:YAG lasers which emit simultaneously at the three harmonically related wavelengths of 1064 nm (infrared), 532 nm (visible green), and 355 nm (ultraviolet). The two-laser system provides redundancy in case one laser fails. Only one laser operates at a time.

Orbiter Experiments Autonomous Support Instrumentation System (OASIS-I)

The OASIS-I is a data-logging, subsystem which was used to record accelerations, acoustic loads, strains temperatures, thermal flux and pressures during the launch, ascent, on-orbit, descent, and landing phases of the LITE mission.

Camera Assembly

The LITE camera is a modified half-frame 35 mm camera originally used for aerial reconnaissance. It was used to photograph the Earth's surface and cloud cover during the daylight portions of orbits when lidar data were acquired. A 25 mm focal length lens was used, giving a coverage of 200 X 200 km2. The time interval between photographs is approximately 21 seconds, giving roughly 20% overlap between successive frames. A GMT time stamp recorded on each frame was used to determine the latitude and longitude on the surface of the Earth that corresponds to the center of each frame. LITE camera photographs may be obtained from the LITE Camera Photographs and Photos and Images pages.

The LITE Camera Photographs page contains the entire set of LITE camera photographs. The photographs are available as JPEG images.

The Photos and Images page contains the LITE camera photographs coincident with daytime LITE observations. The LITE camera photographs are displayed with color-modulated, altitude-time plots of daytime LITE (background subtracted) signal profiles for the 532 nm wavelength. The LITE photographs are available as JPEG images.

Instrument Controller

The Instrument Controller (IC) handles all command and data interfaces of the LITE instrument. All subsystems could be commanded and controlled via the IC. Health and status of the LITE instrument are monitored and transferred to the Spacelab's Smart Flexible Multiplexer/Demultiplexer (SFMDM). The IC software consists of over 18 real-time Ada tasks that perform all commands and data interfaces for the IC as well as autonomous operations.

Instrument Photograph





References.

Winker, D. M., Couch, R. H., and McCormick, M. P., An overview of LITE: NASA's Lidar In-space Technology Experiment, Proc. IEEE, 84, 2, 164-180, Feb. 1996.

McCormick, M. P., Winker, D. M., Browell, E. V., Coakley, J. A., Gardner, C. S., Hoff, R. M., Kent, G. S., Melfi, S. H., Menzies, R. T., Platt, C. M. R., Randall, D. A., and Reagan, J. A., Scientific investigations planned for the Lidar In-space Technology Experiment (LITE), Bull. Amer. Meteorol. Soc., 74, 2, 205-214, Feb. 1993.