This is a sign used at the Vertical Test Stand No. 1 of the Santa Susana Field Laboratory of Rocketdyne in the Santa Susana Mountains, California. The Vertical Test Stand No. 1, or VTS-1, was an important site used by Rocketdyne and its predcessor from the 1950s for the testing of the U.S.'s first large-scale liquid propellant rocket engines, starting with the engine for the Redstone missile.

This engine evolved into the engines for the Thor, Jupiter, and Atlas missiles, the engines for the Saturn V launch vehicle that took men to the Moon, and the Shuttle Main Engine. The VTS-1 was demolished in 1996 but the sign and other parts were retrieved. This object was donated to the Smithsonian by Rocketdyne in 1996.