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The sign accompanying the S-3 rocket engine. It reads

Jupiter S-3 Rocket Engine

A modification of the Redstone engine, the S-3 powered the Jupiter missile, the first U.S. intermediate-range ballistic missile. Rocketdyne began developing the Jupiter engine in 1956. The Jupiter missile was activated in 1958 and was used until 1963. A modified version with additional upper stages, called the Juno II, was developed to launch spacecraft. Junos launched two Pioneer unmanned lunar probes in the late 1950s and put the Explorer 7, 8, and 11 satellites into Earth Orbit.

Transferred from the U.S. Army Center of Military History, Museum Division

Length:	3.6 m (11 ft. 10 in.)
Thrust:	667,000 N (150,000 lb)
Propellants:	liquid oxygen, RP-1 (kerosene)
Manufacturer:	Rocketdyne Div. North American Aviation
	A19910024000

Although the sign states that this is a modified Redstone engine, it is related to the Redstone family of engines only distantly: The Redstone engine and the family of engines including the Jupiter engine both evolved from the original Navaho 75K engine. The Redstone engine was directly evolved from this engine, but the line eventually producing the Jupiter engine included another iteration of the Navaho engine and the S-3D engine's immediate predecessor, the engines developed for the Atlas missile. For additional information about the "family tree" of Rocketdyne engines, see my Rocket engine family tree.

While the sign indicates that the Jupiter was "activated" in 1958, missiles were not actually deployed until 1961.

The same basic engine was used to power the Thor missile. The S-3D engine was later evolved, incorporating many simplifications, into the H-1 engine.