Pathfinder landed on Mars' surface carrying the six-wheeled Sojourner rover, a mobile robot. Rover and lander took over 17,000 pictures, analyzed rocks and soil, and sent back 8.5 million measurements of the red planet's atmospheric pressure, temperature, and wind. Sojourner was operated from Earth by remote control—but the commands took about six minutes to reach Mars.

Image credits: main image, courtesy of JPL, California Institute of Technology and NASA.