The Ice, Cloud and Land Elevation Satellite mission: laser radar science for the NASA Earth Observing System

The Geoscience Laser Altimeter System (GLAS) is a spaceborne laser designed to 1) measure the altitude between the instrument and Earth's surface and 2) measure the vertical distributions of clouds and aerosols. Measurement of altitude, when combined with precise position knowledge of the instrument in space and precise laser pointing knowledge, enables high accuracy determination of surface profiles with respect to the Earth's center of mass. The altitude measurements will be made using laser pulses with wavelengths of 1064 nm (near infrared) and the atmospheric properties will be measured using a 532 nm (green) wavelength. The laser will be pointed in the geodetic nadir direction during typical operations. GLAS is a facility instrument within NASA's Earth Science Enterprise. The Ice, Cloud and Land Elevation Satellite (ICESAT) mission provides overall project management. The GLAS instrument, under development at NASA Goddard Space Flight Center, will be carried by a commercial spacecraft provided by Ball Aerospace (Boulder, Colorado). The ICESAT Observatory (spacecraft plus instrument) is scheduled for launch in 2001 from Vandenberg (CA). The ICESAT Observatory will have an altitude of about 600 km and an orbit inclination of 940. The mission has a 3-year lifetime requirement, with a 5- year goal. It is planned that follow-on orbiting instruments will extend the observation period to 15-yrs and longer.