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The early efforts were directed chiefly toward deployment, structural, and suspension problems, and resulted in a storage-battery-powered vehicle that served as a test bed for later developments. The next phase involved the development of a primitive vision system for detecting obstacles. This consisted of a pulsed laser source and single photodetector both mounted on the same mast. As the mast is rotated, they scan the terrain ahead at fixed elevation angles such that a ground reflection should be received for relatively flat terrain. Azimuth angles for which no ground reflection is received are presumed to contain boulders or craters. This information is processed and used to guide the vehicle by means of telemetry and a remote computer. Results of extensive testing of this vehicle are summarized. A more sophisticated vision system was subsequently developed that continues to use triangulation as a basic feature, but scans the terrain ahead in two dimensions. The improved telemetry system and other hardware and software improvements are discussed, along with some fixed-position test results for this vision system. Some suggestions for the direction of future efforts are included. Problems that were not addressed in this work are obstacle avoidance and navigation for distances over three meters, and autonomous power sources suitable for extended travel.