Thor (launch vehicle)
Encyclopedia
Launch vehicle
In spaceflight, a launch vehicle or carrier rocket is a rocket used to carry a payload from the Earth's surface into outer space. A launch system includes the launch vehicle, the launch pad and other infrastructure....
derived from the PGM-17 Thor
PGM-17 Thor
Thor was the first operational ballistic missile of the U.S. Air Force . 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 with thermonuclear warheads. Thor was in height and in diameter. It was...
intermediate-range ballistic missile
Intermediate-range ballistic missile
An intermediate-range ballistic missile is a ballistic missile with a range of 3,000–5,500 km , between a medium-range ballistic missile and an intercontinental ballistic missile...
. The Thor rocket
Rocket
A rocket is a missile, spacecraft, aircraft or other vehicle which obtains thrust from a rocket engine. In all rockets, the exhaust is formed entirely from propellants carried within the rocket before use. Rocket engines work by action and reaction...
was the first in a large family of space launch vehicles that came to be known as Delta. A derivative of the Thor was still in service as of 2011, as the first stage of the Delta II
Delta II
Delta II was an American space launch system, originally designed and built by McDonnell Douglas. Delta II is part of the Delta rocket family and was in service from 1989 until November 1, 2011...
.
Origins and early history
The first type of space launch mission Thor was asked to perform was testing of the warhead reentry vehicle for the Atlas missile. For these three tests a Thor core stage was topped by a second stage named Able using the Aerojet AJ-10-40AJ-10
The AJ-10 or AJ10 is a hypergolic rocket engine. It has been used to propel the upper stages of several carrier rockets, including the Delta II and Titan III. It will also be used as the main engine of the Orion Crew Exploration Vehicle for NASA's Project Constellation.It was first used in the Able...
engine from the Vanguard
Vanguard rocket
The Vanguard rocket was intended to be the first launch vehicle the United States would use to place a satellite into orbit. Instead, the Sputnik crisis caused by the surprise launch of Sputnik 1 led the U.S., after the failure of Vanguard TV3, to quickly orbit the Explorer 1 satellite using a Juno...
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.
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
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 science payload...
spacecraft into lunar orbit where it would take pictures of the lunar surface with a TV camera. The mission ended prematurely at 77 seconds after launch on August 17, 1958, due to a turbopump failure.
On August 7, 1959 a Thor-Able was used to successfully launch Explorer 6
Explorer 6
Explorer 6 was a United States 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...
, the first satellite to transmit pictures of Earth taken from orbit.
Ablestar
Ablestar was a liquid rocketLiquid rocket
A liquid-propellant rocket or a liquid rocket is a rocket engine that uses propellants in liquid form. Liquids are desirable because their reasonably high density allows the volume of the propellant tanks to be relatively low, and it is possible to use lightweight pumps to pump the propellant from...
stage burning hypergolic propellants fed from gas-pressurized propellant tanks. It was used as the upper stage, and provided improved performance. On April 13, 1960 a Thor-Ablestar launched Transit 1B, the first experimental satellite to demonstrate the feasibility of using satellites as navigation aids
Global Navigation Satellite System
A satellite navigation or SAT NAV system is a system of satellites that provide autonomous geo-spatial positioning with global coverage. It allows small electronic receivers to determine their location to within a few metres using time signals transmitted along a line-of-sight by radio from...
. On June 22, 1960, a Thor-Ablestar launched the first Galactic Radiation and Background
Galactic Radiation and Background
Galactic Radiation and Background was the covername for Project Dyno ELINT intelligence satellites operated by the U.S. Naval Research Laboratory shortly after the Cold War U-2 incident of 1960...
(GRAB) electronic intelligence (ELINT) satellite for the United States Navy
United States Navy
The United States Navy is the naval warfare service branch of the United States Armed Forces and one of the seven uniformed services of the United States. The U.S. Navy is the largest in the world; its battle fleet tonnage is greater than that of the next 13 largest navies combined. The U.S...
. 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. GRAB-1 was thus the world's first successful reconnaissance satellite, preceding the first Corona
Corona (satellite)
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...
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
Space debris
Space debris, also known as orbital debris, space junk, and space waste, is the collection of objects in orbit around Earth that were created by humans but no longer serve any useful purpose. These objects consist of everything from spent rocket stages and defunct satellites to erosion, explosion...
.
Thor and the Corona program
Thor formed the core of the Thor-AgenaThor-Agena
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...
vehicle used to launch the early Corona
Corona (satellite)
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...
(also known as "Keyhole" and "Discoverer") satellites from Vandenberg AFB.
These were the first photographic spy satellites, used for photographic surveillance of the Soviet Union
Soviet Union
The Soviet Union , officially the Union of Soviet Socialist Republics , was a constitutionally socialist state that existed in Eurasia between 1922 and 1991....
, China
China
Chinese civilization may refer to:* China for more general discussion of the country.* Chinese culture* Greater China, the transnational community of ethnic Chinese.* History of China* Sinosphere, the area historically affected by Chinese culture...
and other areas. Thor-Agenas were used as launch vehicles for Corona satellites from June 1959 through May 1963.
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 AgenaRM-81 Agena
The RM-81 Agena was an American rocket upper stage and satellite support bus which was developed by Lockheed initially for the canceled WS-117L reconnaissance satellite program...
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 miles (185.2 km) polar circular orbits.
Thrust Augmented Thor
The Thrust Augmented Thor, or TAT, was developed to handle the growing recon sats of the CoronaCorona (satellite)
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...
program. It added three Castor
Castor (rocket stage)
The Castor family of solid-fuel rocket stages and boosters were built by Thiokol and used on a variety of launch vehicles. They were initially developed as the second stage motor of the Scout rocket...
solid rocket strapon boosters—each providing 53,000 lbf (236 kN) thrust—to the standard Thor core stage. The boosters were lit on the ground and jettisoned after burnout.
Thorad
The Thorad-AgenaThorad-Agena
The Thorad-Agena was an American expendable launch system, derived from the Thor and Delta rockets. The first stage of the rocket was the stretched variant of the Thor which had been developed for the Delta programme. The second stage was the Agena-D, which had already been used in conjunction with...
(pictured) was developed from Thor. It used a Thor, modified for use as a Delta rocket, to launch an Agena
RM-81 Agena
The RM-81 Agena was an American rocket upper stage and satellite support bus which was developed by Lockheed initially for the canceled WS-117L reconnaissance satellite program...
upper stage.
Long Tank Thor
- Tapered fuel tank changed to cylindrical.
- Both tanks lengthened.
- Core stage 14 feet (4.3 m) longer.
- 49,000 lb (22,000 kg) more propellant.