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Interest in lasers for space applications such as active remote sensing in Earth orbit, planetary science, and inter-satellite laser communications is growing. These instruments typically use diode-pumped solid state lasers for the laser transmitter. The mission specifications and constraints of space qualification, place strict requirements on the design and operation of the laser. Although a laser can be built in the laboratory to meet performance specifications relatively routinely, tile mission constraints demand unique options and compromises in the materials used, and design to ensure the success of the mission. Presently, the best laser architecture for a light weight, rugged, high peak power and efficient transmitter is a diode laser pumped ND:YAG laser. Diode lasers can often obviate the need for water cooling, reduce the size and weight of the laser, increase the electrical to optical efficiency, system reliability, and lifetime. This paper describes the in-space operation and performance of the Mars Orbiter Laser Altimeter (MOLA) laser transmitter, representing the current state-of-the-art in space-based solid- state lasers.

The Goddard Visible and Near IR Lidar(VIRL) 1 has been modified to the 2.1um region by replacing the Raman cell previously used to generate the 1.54 um pulse with an Optical Parametric Oscillator (OPO) 2 that can efficiently convert the 1.064um output of the system Nd:YAG laser to generate a pulse at 2.1um. The initial test and application of the 2.1um measurements was during a deployment of the lidar on the NASA DC-8 for the TOGA/COARE project in January-February 1993. For T/C, the DC-8 was flown to and out of Townsville, Queensland. The T/C flights were north to the region of the equator and back. From the transit and local flights, a data set of significant coverage is to be generated.