Two Jet Propulsion Laboratory
engineers stand with three vehicles, providing a size comparison of three generations of Mars rovers. Front and center is the flight spare for the first Mars rover, Sojourner
, which landed on Mars in 1997 as part of the Mars Pathfinder Project. On the left is a Mars Exploration Rover (MER) test vehicle that is a working sibling to Spirit
, which landed on Mars in 2004. On the right is a test rover for the Mars Science Laboratory, which landed Curiosity
on Mars in 2012. Sojourner
is 65 cm (2.13 ft) long. The Mars Exploration Rovers (MER) are 1.6 m (5.2 ft) long. Curiosity
on the right is 3 m (9.8 ft) long.