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The sign accompanying the missile. It reads

Thor
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 missile.

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 signals.

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 December 1963.

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 Attack-Missile)

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 each)

Warhead: Nuclear (Single RV)

Apogee: 250 mi

Versions: Thor-Agena, Thor-Able-Star

Years of service: 1959-1963

I also have pictures of the Thor-Agena at the Air Force Museum.