The maximum speed of the Sojourner rover was 1 centimeter per second.
Sojourner was NASA’s small robotic rover on the Mars Pathfinder mission, which landed on Mars on July 4, 1997. Built as a technology demonstration, it was designed to show that a lightweight, wheeled vehicle could operate on another planet and investigate rocks and soil near its lander.
At 1 cm/s, Sojourner moved only 0.036 kilometers per hour, or about 86.4 meters in a full hour of continuous driving. Its slow pace was intentional: controllers had to navigate around rocks, slopes, and other hazards using images and data transmitted from Mars, where communication delays made direct joystick-style driving impossible.
A common mix-up is confusing Sojourner’s maximum speed with the distance it could travel. The rover could reach roughly 500 meters from the Pathfinder lander, limited largely by communications. Sojourner also carried the Alpha Proton X-ray Spectrometer, which analyzed the composition of Martian rocks and soil.