Sojourner on Mars and Lessons Learned for Future Planetary Rovers

On July 4, 1997, the Mars Pathfinder spacecraft successfully landed on Mars in the Ares Vallis landing site and deployed an 11.5-kilogram microrover named Sojourner. This microrover accomplished its primary mission objectives in the first 7 days, and continued to operate for a total of 83 sols (1 sol = Mars day = 1 Earth day + ∼24 mins) until the lander lost communication with Earth, probably due to lander battery failure. The microrover navigated to many sites surrounding the lander, and conducted various science and technology experiments using its on-board instruments. In this paper, the rover navigation performance is analyzed on the basis of received rover telemetry, rover uplink commands and stereo images captured by the lander cameras. Its physical traversal path is redrawn from the stereo images containing tracks and is compared with the rover-recorded path and the driver-planned path. Implications for next-generation planetary rovers are described, including the sub-1-Kg Nanorover being built by NASA to conduct asteroid exploration as part of the Japanese MUSES-C sample return mission and the large rover with the Athena payload which will be used as part of the Mars sample return program.