The Mars Exploration Rover (MER) Surface System Test-Bed (SSTB) on display at the Udvar-Hazy Center in Chantilly, Virginia. The rover is nearly identical to the twin rovers "Spirit" and "Opportunity," which landed on mars in 2004. The main difference is that this rover was designed for use on Earth. It spent its life up until recently crawling around the In-Situ Instruments Laboratory at NASA's Jet Propulsion Laboratory.
The model joined the collection in 2019, and will eventually go on display in the museum's building in Washington, D.C. in one of the first new galleries scheduled to open in late 2022.