Significant technological advances were made toward utilizing the Hale telescope for receiving the faint laser communication signals transmitted from an optical transceiver on a spacecraft orbiting Mars. The so-called Palomar receive terminal design, which would have supported nominal downlink data rates of 1-30 Mbps, is described. Testing to validate technologies for near-Sun (3deg from edge of solar disc) daytime operations is also discussed. Finally, a laboratory end-to-end link utilizing a 64-ary pulse-position modulated photon-counting receiver and decoder that achieved predicted near-capacity (within 1.4 dB) performance is described.

Sun sensors are widely used in spacecraft attitude determination subsystems to provide a measurement of the Sun vector in spacecraft coordinates. At the Jet Propulsion Laboratory, California Institute of Technology, there is an ongoing research activity to utilize Micro Electro Mechanical Systems (MEMS) processes to develop a smaller and lighter Sun sensor for space applications. A prototype Sun sensor has been designed and constructed. It consists of a piece of silicon coated with a thin layer of chrome, and a layer of gold with hundreds of small pinholes, placed on top of an image detector at a distance of less than a millimeter. Images of the Sun are formed on the detector when the Sun illuminates the assembly. Software algorithms must be able to identify the individual pinholes on the image detector and calculate the angle to the Sun. Fuzzy image processing is utilized in this process. This paper describes how the fuzzy image processing is implemented in the instrument. Also, a camera pin hole model is constructed and used to evaluate the accuracy of the Sun sensor.