Russian robotic rover Lunokhod 1 landed on the moon in 1970, and traveled about 6 miles (10 km) before vanishing from detection in September 1971.
IRobot has been building larger robotic rovers that are used for bomb disposal and other hazardous tasks, but the challenge was putting everything into a five-pound package that doesn't fall apart.
"It then deployed instruments, including Sojourner, a small, six-wheeled robotic rover, which explored as far as 1,600 ft (500 m) from the lander and sent pictures Back for over a month."