SM-78 Jupiter


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The SM-78 Jupiter was a medium-range, ground-launched, liquid-fueled ballistic missile developed and deployed by the United States. Due to its limited range, the Jupiter was forward based to allied European countries for deterrence against the Soviet Union.

SM-78 Jupiter at a Glance

Originated From
United States
Class
Medium-range Ballistic Missile (MRBM)
Possessed By
United States
Basing
Ground-based
Length
18.39 m
Diameter
2.67 m
Launch Weight
49,885 kg
Payload
Single warhead, Mk 3/4 RV
Warhead
W-49, 1.5 mT Nuclear
Propulsion
Single-stage, liquid propellant
Range
2,400 km
Status
Obsolete
In Service
1958-1964

SM-78 Jupiter Development

The Jupiter began development in 1954 under the supervision of Dr. Werner Von Braun, with many of its components constructed by the Chrysler Corporation. It was the first U.S. medium-range ballistic missile (MRBM), and was designed to replace the U.S. Army’s shorter-ranged PGM-11 Redstone missile. From its beginning, the project faced criticism from Air Force leaders who believed that the missile’s range made it a strategic weapon, not a battlefield support weapon, which they considered to be an encroachment on their mission by the Army.

The conflict between the Army and the Air Force grew when the Air Force began developing its IRBM, the Thor. Throughout 1956, the Army and Air Force disagreement made national headlines when officials from both branches began denouncing the other publicly.

In order to end the dispute, Secretary of Defense Charles Wilson signed a memorandum in November 1956 stating that the Jupiter would be transferred to the Air Force and the Army would be limited to developing short range and battlefield support weapons with ranges of less than 320 km.1

The Jupiter missile was also considered by the Navy for a sea-launched system, which led to a collaborative development effort between the Army and Navy. The sea-launched missile concept later evolved into the Navy’s Polaris sub launched ballistic missile (SLBM) program.

The Jupiter was first flight tested in 1957 and entered operation service in 1959.

Specifications

The Jupiter missile had a range of 2,400 km with the same Mk 3 and 4 reentry vehicles and used the same 1.44 MT W-49 warheads used on the Atlas missile. It featured an inertial navigation system which, though only accurate to 1,800 m CEP, was revolutionary at its time. The missile was 18.39 m long, 2.67 m wide and weighed 49,885 kg at launch.2

It was roughly the size of most modern intercontinental missiles, it had a significantly shorter range due to its extremely heavy single-stage liquid propellant design.

Service History

The Jupiter was a theater-based system intended for use against strategic targets. While the Jupiter’s navigation system was quite accurate for its time, the missile was ineffective at destroying hardened targets due to its 1.8 km CEP. However, the missile was capable of targeting cities, major staging areas, and troop transit points in the event of hostilities. After the missiles were transferred to the Air Force in 1956, the Air Force chose to transition the Jupiter to a fixed-launch missile, as the Army’s mobile variant was dependent on ground vehicles the Air Force did not possess.3

In 1958 and 1959, Jupiters were deployed to Italy and Turkey as a forward strike capability.4 30 missiles were deployed to Italy and 15 to Turkey. An additional 15 missiles were scheduled for deployment to Turkey, but these plans were later canceled.5

The missiles in Italy provided a direct nuclear threat against the Soviet Union, its satellite states and armed forces, and played a reassurance role for U.S. European allies. Meanwhile, the missiles based in Turkey were capable of threatening Moscow and other major Russian cities.

During the Cuban Missile Crisis in late 1962, the Kennedy Administration quietly negotiated the removal of Soviet SS-4 and SS-5 missiles from Cuba by removing the Jupiter missiles based in Italy and Turkey. All Jupiter missiles were retired two years later in 1964.6

Modified Jupiter missiles were used as the first stage boosters of the Juno satellite launch vehicles. Jupiter missiles were used to put the U.S. Explorer satellites into orbit.7

Footnotes

    1. David Baker. The Rocket: The History and Development of Rocket & Missile Technology. (New York: Crown Publishers, 1978.)
    2. David Baker. The Rocket: The History and Development of Rocket & Missile Technology. (New York: Crown Publishers, 1978.)
    3. Donald Mackenzie. Inventing Accuracy: A Historical Sociology of Nuclear Missile Guidance. (MIT Press, 1993.)
    4. David Baker. The Rocket: The History and Development of Rocket & Missile Technology. (New York: Crown Publishers, 1978.)
    5. David Baker. The Rocket: The History and Development of Rocket & Missile Technology. (New York: Crown Publishers, 1978.)
    6. James Gibson. The Navajo Missile Project: The Story of the “Know-How” Missile of American Rocketry. (Schiffer Publishing Ltd, 1996.)
    7. Duncan Lennox. “SM-78 Jupiter,” in Jane’s Strategic Weapon Systems (Offensive Weapons). (London: IHS Global 2011.)
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Missile Defense Project, "SM-78 Jupiter," Missile Threat, Center for Strategic and International Studies, December 20, 2016, last modified May 18, 2021, https://missilethreat.csis.org/missile/jupiter/.