Feature Story

Days of thunder

The Thor intermediate-range ballistic missile

Boeing Archives

The Thor intermediate-range ballistic missile was used to launch vehicles into space for research on re-entry.

In Norse mythology, Thor was the god of thunder, wielding a mighty hammer that flashed lighting across the sky.

It was a fitting name for the first operational ballistic missile deployed by the U.S. Air Force.

The Thor missile, developed in the 1950s by Boeing heritage company Douglas Aircraft, never had to wield its own hammer -- a nuclear warhead -- but it served as an early nuclear deterrent before the development of longer-range intercontinental ballistic missiles (ICBMs) such as Minuteman.

Thor also left an important legacy. It was modified to become the highly successful Delta launch vehicle, an eventual family of Boeing rockets that continue to hurtle military and commercial satellites into orbit to this day -- satellites that make possible everything from global communications to forecasting the weather.

The single-stage, liquid-fueled Thor was designed as an intermediate-range ballistic missile to meet Air Force requirements for a missile capable of accurately delivering a payload 1,500 miles (2,400 kilometers) from its launch site. A missile with that range could hit Moscow from the United Kingdom. The Korean War had ended, but the Cold War was escalating and the United States wanted not only the ability to respond to nuclear threats but, more important, a deterrent to nuclear war.

In late November 1955, three companies were given one week to bid on the project -- Douglas, Lockheed and North American Aviation. On Dec. 23, 1955, the Air Force selected Douglas as prime contractor for the missile’s airframe and integration, while North American Aviation’s Rocketdyne division was awarded the contact for the engine, which would produce 135,000 pounds (600 kilonewtons) of thrust.

North American also is a Boeing heritage company. Donald W. Douglas Jr., president of Douglas Aircraft Co., noted at the time: “In point of experience and volume of production, the Douglas Santa Monica Division holds a position of unquestioned leadership as a manufacturer of missiles. ... Our output of missiles since we entered the business in 1941 numbers more than 19,000 and by weight exceeds that of all other American missile manufacturers combined.”

Thor measured 8 feet (2.4 meters) in diameter and was 65 feet (20 meters) long, and could be transported by a Douglas C-124 Globemaster for rapid deployment if needed.

After several failures, Thor made its first successful flight in September 1957.

It reached a speed of about 10,000 mph (4.5 kilometers per second) and attained an altitude of 1,100 miles (1,800 kilometers) before the inert warhead splashed into the south Atlantic Ocean. Further testing continued and in August 1958, after 18 research-and-development launches, Thor was cleared for operational use.

Under the code name Operation Go Away, the first Thor operational missiles were deployed in the United Kingdom in September 1958, and by April 1960 four Royal Air Force squadrons had 60 missiles. They were all deployed at above-ground launch sites, stored horizontally on transporter-erector trailers.

More than 200 Thor missiles were built. But once the first generation of ICBMs based in the United States became operational, Thor was no longer needed and the missiles were quickly retired. Thor was deactivated in 1966.

“The capability of sending such a missile hurtling above the earth’s atmosphere at supersonic speeds has tremendous implications,” Douglas said of Thor. But his words also could have been used to describe the more powerful ICBMs that took Thor’s place.

“Any nation so armed can strike devastating blows at any adversary with only a moment’s notice,” Douglas noted. “Perhaps this is truly the ultimate weapon which no one will dare to use. Yet we must be prepared to use it if we have to and to take countermeasures against similar weapons that might be used against us.”