Thor (rocket family)

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Thor Able with Pioneer 1 at Cape Canaveral in Florida Pioneer I on the Launch Pad - GPN-2002-000204.jpg
Thor Able with Pioneer 1 at Cape Canaveral in Florida

Thor was an American space launch vehicle derived from the PGM-17 Thor intermediate-range ballistic missile. The Thor rocket was the first in a large family of space launch vehicles that came to be known as Delta . The last derivative of the Thor was retired in 2018, which was the first stage of the Delta II.

Launch vehicle rocket used to carry payload into outer space

A launch vehicle or carrier rocket is a rocket used to carry a payload from Earth's surface through outer space, either to another surface point, or into space. A launch system includes the launch vehicle, launch pad, vehicle assembly and fuelling systems, range safety, and other related infrastructure.

PGM-17 Thor first operational ballistic missile deployed by the U.S. Air Force

Thor was the first operational ballistic missile deployed by the U.S. Air Force (USAF). Named after the Norse god of thunder, it was deployed in the United Kingdom between 1959 and September 1963 as an intermediate-range ballistic missile (IRBM) with thermonuclear warheads. Thor was 65 feet (20 m) in height and 8 feet (2.4 m) in diameter. It was later augmented in the U.S. IRBM arsenal by the Jupiter.

Intermediate-range ballistic missile ballistic missile with a range of 3,000–5,500 km

An intermediate-range ballistic missile (IRBM) is a ballistic missile with a range of 3,000–5,500 km, between a medium-range ballistic missile (MRBM) and an intercontinental ballistic missile (ICBM). Classifying ballistic missiles by range is done mostly for convenience; in principle there is very little difference between a low-performance ICBM and a high-performance IRBM, because decreasing payload mass can increase range over ICBM threshold. The range definition used here is used within the U.S. Missile Defense Agency. Some other sources include an additional category, the long-range ballistic missile (LRBM), to describe missiles with a range between IRBMs and true ICBMs. The more modern term theater ballistic missile encompasses MRBMs and SRBMs, including any ballistic missile with a range under 3,500 km (2,175 mi).


Origins and early history

Thor Able on display at LC-26B of the Air Force Space & Missile Museum LC-26B Thor-Able.jpg
Thor Able on display at LC-26B of the Air Force Space & Missile Museum

The first type of space launch mission Thor was asked to perform was testing of the warhead reentry vehicle for the Atlas missile . [1] For these three tests a Thor core stage was topped by a second stage named Able using the Aerojet AJ-10-40 engine from the Vanguard second stage. The first such launch, 116, was lost April 23, 1958 due to a turbopump failure in the main engine. The recovery of the reentry vehicles on the succeeding two attempts were not successful. Three mice, one on each vehicle, died in these tests. [2]

Able (rocket stage)

Able rocket stage was a rocket stage manufactured in the United States by Aerojet for the Vanguard rockets used in the Vanguard project from 1957 to 1959. The rocket engine stage use as a rocket propellant Nitric acid and UDMH. Able rocket stage was the second of three stages on the multistage rocket Vanguard. The Able rocket stage was discontinued in 1960. A further improved versions were used in the upper stage in the Thor rocket family (Thor-Able). An upgrade to the Able Stage was the Thor-Ablestar rocket. The Ablestar second stage was an enlarged version of the Able rocket stage, which gave the Thor-Ablestar a greater payload capacity compared to the Thor-Able. It also incorporated restart capabilities, allowing a multiple-burn trajectory to be flown, further increasing payload, or allowing the rocket to reach different orbits. It was the first rocket to be developed with such a capability and development of the stage took a mere eight months.

Laboratory mouse animal used in labs

The laboratory mouse is a small mammal of the order Rodentia which is bred and used for scientific research. Laboratory mice are usually of the species Mus musculus. They are the most commonly used mammalian research model and are used for research in genetics, psychology, medicine and other scientific disciplines. Mice belong to the Euarchontoglires clade, which includes humans. This close relationship, the associated high homology with humans, their ease of maintenance and handling, and their high reproduction rate, make mice particularly suitable models for human-oriented research. The laboratory mouse genome has been sequenced and many mouse genes have human homologues.

The Able stage from the Atlas reentry vehicle tests was upgraded (to become the Able I) with a third stage consisting of an unguided Altair X-248 solid rocket motor. A Thor Able I was used in an attempt to place the 84 lb (38 kg) Pioneer 0 spacecraft into lunar orbit where it would take pictures of the lunar surface with a TV camera. The mission ended prematurely at 73.6 seconds after launch on August 17, 1958, due to a turbopump failure.

Pioneer 0

Pioneer 0 was a failed United States space probe that was designed to go into orbit around the Moon, carrying a television camera, a micrometeorite detector and a magnetometer, as part of the first International Geophysical Year (IGY) science payload. It was designed by the United States Air Force (USAF) as the first satellite in the Pioneer program and was one of the first attempted launches beyond Earth orbit by any country, but the rocket failed shortly after launch. The probe was intended to be called Pioneer, but the launch failure precluded that name.

On August 7, 1959 a Thor-Able was used to successfully launch Explorer 6, the first satellite to transmit pictures of Earth taken from orbit.

Explorer 6

Explorer 6, or S-2, was an American satellite launched on August 7, 1959. It was a small, spheroidal satellite designed to study trapped radiation of various energies, galactic cosmic rays, geomagnetism, radio propagation in the upper atmosphere, and the flux of micrometeorites. It also tested a scanning device designed for photographing the Earth's cloud cover, and transmitted the first pictures of Earth from orbit.


Ablestar was a liquid rocket stage burning hypergolic propellants fed from gas-pressurized propellant tanks. It was used as the upper stage, and provided improved performance. [3] On April 13, 1960 a Thor-Ablestar launched Transit 1B, the first experimental satellite to demonstrate the feasibility of using satellites as navigation aids. [4] On June 22, 1960, a Thor-Ablestar launched the first Galactic Radiation and Background (GRAB) electronic intelligence (ELINT) satellite for the United States Navy. These now-declassified satellites, operated under a cover story of providing solar radiation data, included an electronics package to detect Soviet air defense radar signals. [5] GRAB-1 was thus the world's first successful reconnaissance satellite, preceding the first Corona mission to return film (Discoverer 14 on August 18) by almost two months. On 1961-06-29 the Ablestar stage used to launch Transit 4A became the first object to unintentionally explode in space, creating at least 294 trackable pieces of space debris. [6]

Galactic Radiation and Background

Galactic Radiation and Background (GRAB) was the covername for a series of five Project Dyno ELINT intelligence satellites, the first surveillance satellites operated by the U.S. Naval Research Laboratory (NRL) shortly after the Cold War U-2 incident of 1960. Though only two of the five satellites made it into orbit, they returned a wealth of information on Soviet air defense radar capabilities.

United States Navy Naval warfare branch of the United States Armed Forces

The United States Navy (USN) is the naval warfare service branch of the United States Armed Forces and one of the seven uniformed services of the United States. It is the largest and most capable navy in the world and it has been estimated that in terms of tonnage of its active battle fleet alone, it is larger than the next 13 navies combined, which includes 11 U.S. allies or partner nations. with the highest combined battle fleet tonnage and the world's largest aircraft carrier fleet, with eleven in service, and two new carriers under construction. With 319,421 personnel on active duty and 99,616 in the Ready Reserve, the Navy is the third largest of the service branches. It has 282 deployable combat vessels and more than 3,700 operational aircraft as of March 2018, making it the second largest and second most powerful air force in the world.

Reconnaissance satellite satellite collecting intelligence

A reconnaissance satellite or intelligence satellite is an Earth observation satellite or communications satellite deployed for military or intelligence applications.

Thorad-Agena D with SERT-2 satellite at Space Launch Complex 2 East (SLC-2E), Vandenberg AFB, California. Thorad Agena with SERT-2.jpg
Thorad-Agena D with SERT-2 satellite at Space Launch Complex 2 East (SLC-2E), Vandenberg AFB, California.

Thor and the Corona program

Thor formed the core of the Thor-Agena vehicle used to launch the early Corona (also known as "Keyhole" and "Discoverer") satellites from Vandenberg AFB. [7] These were the first photographic spy satellites, used for photographic surveillance of the Soviet Union, China and other areas. Thor-Agenas were used as launch vehicles for Corona satellites from June 1959 through May 1963.

Thor-Agena rocket developed in the USA

Thor-Agena was a series of orbital launch vehicles. The rockets used Thor first stages and Agena second stages. They are thus cousins of the more-famous Thor-Deltas, which founded the Delta rocket family. The first attempted launch of a Thor-Agena was in January 1959. The first successful launch was on February 28, 1959, launching Discoverer 1.

Corona (satellite) series of American strategic reconnaissance satellites

The Corona program was a series of American strategic reconnaissance satellites produced and operated by the Central Intelligence Agency Directorate of Science & Technology with substantial assistance from the U.S. Air Force. The Corona satellites were used for photographic surveillance of the Soviet Union (USSR), the People's Republic of China, and other areas beginning in June 1959 and ending in May 1972. The name of this program is sometimes seen in pre-ASCII all caps as "CORONA", but in mixed caps, its actual name "Corona" was a codeword, not an acronym.

Soviet Union 1922–1991 country in Europe and Asia

The Soviet Union, officially the Union of Soviet Socialist Republics (USSR), was a socialist state in Eurasia that existed from 30 December 1922 to 26 December 1991. Nominally a union of multiple national Soviet republics, its government and economy were highly centralized. The country was a one-party state, governed by the Communist Party with Moscow as its capital in its largest republic, the Russian Soviet Federative Socialist Republic. Other major urban centres were Leningrad, Kiev, Minsk, Alma-Ata, and Novosibirsk.

Thor spawns Delta

A fourth modification to Thor for space launch purposes, the Thor-Delta, has proven to be the longest-lasting of all Thor-derived rockets. Members of the Delta rocket family derived from the Thor-Delta continue to launch satellites and space probes.

By 1969 the Thor core was being used regularly both in Delta vehicles and in the USAF Standard Space Launch Vehicle (SLV-2), with thrust augmentation and a variety of upper stages.

Use with Agena upper stage

The Thrust-Augmented Thor (TAT) was used with the Agena upper stage, as was the Thrust-Augmented Long Tank Thor/Agena, capable of sending payloads ranging from 1400 to about 2800 pounds into 100-nautical-mile (190 km) polar circular orbits. [8]

Thrust Augmented Thor

The Thrust Augmented Thor, or TAT, was developed to handle the growing recon sats of the Corona program. It added three Castor solid rocket strapon boosterseach providing 53,000 lbf (236 kN) thrustto the standard Thor core stage. The boosters were lit on the ground and jettisoned after burnout.


The Thorad-Agena (pictured) was developed from Thor. It used a Thor, modified for use as a Delta rocket, to launch an Agena upper stage.

Long Tank Thor

See also


  1. Deny Rocket Lag. Atlas Firing Keynotes U.S. Missile Build-Up, 1959/01/29 (1959). Universal Newsreel. 1959. Retrieved February 22, 2012.
  2. [ citation needed ]
  3. [ citation needed ]
  4. "Transit 1B - NSSDC ID: 1960-003B". NASA NSSDC.
  5. "GRAB: 1st Recon Satellite". U.S. Navy.
  6. "Orbital Debris: A Chronology" (PDF). NASA JSC. 1999. p. 18. Archived from the original (PDF) on 2000-09-01.
  7. "Corona". NASA. Archived from the original on 2007-03-11.
  8. Bleymaier, Joseph S. "Future Space Booster Requirements". USAF.

Related Research Articles

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Delta (rocket family) rocket family

Delta is an American versatile family of expendable launch systems that has provided space launch capability in the United States since 1960. There have been more than 300 Delta rockets launched, with a 95% success rate. Only the Delta IV remains in use as of 2018. Delta rockets are currently manufactured and launched by the United Launch Alliance.

Titan IIIB

Titan IIIB was the collective name for a number of derivatives of the Titan II ICBM and Titan III launch vehicle, modified by the addition of an Agena upper stage. It consisted of four separate rockets. The Titan 23B was a basic Titan II with an Agena upper stage, and the Titan 24B was the same concept, but using the slightly enlarged Titan IIIM rocket as the base. The Titan 33B was a Titan 23B with the Agena enclosed in an enlarged fairing, in order to allow larger payloads to be launched. The final member of the Titan IIIB family was the Titan 34B which was a Titan 24B with the larger fairing used on the Titan 33B.

The Delta III rocket was an expendable launch vehicle made by Boeing. The first Delta III launch was on August 26, 1998. Of its three flights, the first two were failures, and the third, though declared successful, reached the low end of its targeted orbit range and carried only a dummy (inert) payload. The Delta III could deliver up to 8,400 pounds to geostationary transfer orbit, twice the payload of its predecessor, the Delta II. Under the 4-digit designation system from earlier Delta rockets, the Delta III is classified as the Delta 8930.

Thor-Able American expendable launch system and sounding rocket used for a series of re-entry vehicle tests and satellite launches between 1958 and 1960

The Thor-Able was an American expendable launch system and sounding rocket used for a series of re-entry vehicle tests and satellite launches between 1958 and 1960. It was a two stage rocket, consisting of a Thor IRBM as a first stage and a Vanguard-derived Able second stage. On some flights, an Altair solid rocket motor was added as a third stage. It was a member of the Thor family and an early predecessor of the Delta.

Scout (rocket family) family of American rockets

The Scout family of rockets were American launch vehicles designed to place small satellites into orbit around the Earth. The Scout multistage rocket was the first orbital launch vehicle to be entirely composed of solid fuel stages.


The Atlas-Centaur was an American expendable launch system derived from the SM-65 Atlas D missile. Launches were conducted from Launch Complex 36 at the Cape Canaveral Air Force Station in Florida.

Vandenberg AFB Space Launch Complex 3 launch site at Vandenberg Air Force Base in California

Space Launch Complex 3 (SLC-3) is a launch site at Vandenberg Air Force Base that has been used by Atlas and Thor rockets. It was built in the early 1960s and consists of two pads, SLC-3E (East) and SLC-3W (West). The East-West coastline at Vandenberg allows SLC-3 to launch over-ocean polar trajectories that avoid landfall until passing over Antarctica. By contrast, Cape Canaveral has a North-South coastline permitting over-ocean launches into standard orbits.

Atlas-Agena expendable launch system

The Atlas-Agena was an American expendable launch system derived from the SM-65 Atlas missile. It was a member of the Atlas family of rockets, and was launched 109 times between 1960 and 1978. It was used to launch the first five Mariner unmanned probes to the planets Venus and Mars, and the Ranger and Lunar Orbiter unmanned probes to the Moon. The upper stage was also used as an unmanned orbital target vehicle for the Gemini manned spacecraft to practice rendezvous and docking. However, the launch vehicle family was originally developed for the Air Force and most of its launches were classified DoD payloads.

Castor (rocket stage) family of solid-fuel rocket stages and boosters

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Atlas (rocket family) family of American missiles and space launch vehicles

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Thorad-Agena rocket developed by the USA, more powerful than the Thor-Agena

The Thorad-Agena was an American expendable launch system, derived from the Thor and Delta rockets. The first stage of the rocket was a stretched Thor variant named "Long Tank Thrust Augmented Thor". The Long Tank Thor first stage was later adopted by NASA's Delta program for its "Thrust Augmented Improved Delta", which first flew in 1968. The second stage was the Agena-D, which had already been used in conjunction with the standard configuration Thor, as the Thor-Agena. Three Castor rockets would be used as boosters. Most launches carried Corona (KeyHole) reconnaissance satellites, particularly spacecraft of the KH-4 series, however some scientific and technology development satellites were also flown, mostly towards the end of the program.

The Atlas SLV-3, or SLV-3 Atlas was an American expendable launch system derived from the SM-65 Atlas / SM-65D Atlas missile. It was a member of the Atlas family of rockets.

Delta L

The Delta L, Thor-Delta L, or Thrust-Augmented Long Tank Thor-Delta was a US expendable launch system used to launch the Pioneer E and TETR satellites in 1969 (failed) and HEOS satellite in 1972. It was a member of the Delta family of rockets.

Delta N

The Delta N or Thor-Delta N was an American expendable launch system used for nine orbital launches between 1968 and 1972. It was a member of the Delta family of rockets, and the last Delta to be given an alphabetical designation - subsequent rockets were designated using a four digit numerical code.

The Star is a family of American solid-fuel rocket motors used by many space propulsion and launch vehicle stages. It is used almost exclusively as an upper stage.