The sign accompanying the missile. It reads
Intermediate-Range Ballistic Missile
The Thor missile, known as one of the most reliable and
versatile launch vehicles in the history of the U.S. missile program, was
developed as the world's first operational intermediate-range ballistic
Used as the booster stages for many space probes, the Thor provided in 1958 the
first stage for the Pioneer moon rocket that discovered the existence of the
Van Allen Radiation Belts.
That same year, the Discoverer satellite was put into the first polar orbit,
thanks to the Thor-Agena. By the end of 1962, the Thor missile had completed
100 space launchings with a 93 percent success record.
The Thor was one of two IRBMs developed by the United States. Development
began in late 1955, and the first missile was delivered to Cape Canaveral in
October 1956 -- a record-setting schedule for a modern weapon system.
In December 1958, the Thor became the first ballistic missile launched by an
all-SAC crew. Thor missiles were deployed in England beginning in 1958 under a
joint USAF-RAF "two key" program. A total force of twenty squadrons, each
equipped with three missiles, was operational by 1961.
Two versions of the Thor were developed: the Thor-Agena and the
Thor-Able-Star. The unique feature of the Thor-Agena was its restartable
second stage, which permitted great precision in selecting an orbit. The
Thor-Agena became the world's most widely used launch vehicle.
The Thor-Able-Star successfully launched the Tiros weather satellite and the
Echo satellite, an inflatable aluminum balloon designed to reflect radio
Two factors led to the phase-out of the Thor as a nuclear deterrent: creation
of the U.S. ICBM program and the British decision to rely on Polaris submarines
for its primary nuclear deterrent force. All Thor missiles were deactivated by
This missile is on loan from the U.S. Air Force Museum Program.
Specifications of the Thor
Purpose: Intermediate-range ballistic missile (IRBM)
Designation: SM-75/PGM-17 (Strategic Missile/Soft Pad-Surface
Manufacturer: Douglas Aircraft
Weight: 105,000 lb
Range: 2,000 mi
Speed: 12,100 MPH
Propulsion: 1 North American Rocketdyne LR-79 engine, 150,000-lb
static thrust and liquid-oxygen fuel (2 vernier rockets, 1,000-lb static thrust
Warhead: Nuclear (Single RV)
Apogee: 250 mi
Versions: Thor-Agena, Thor-Able-Star
Years of service: 1959-1963