The Delta 1000 series (also referred to as Straight-Eight) was an American

expendable launch system An expendable launch system (or expendable launch vehicle/ELV) is a launch vehicle that can be launched only once, after which its components are either destroyed during reentry or discarded in space. ELVs typically consist of several rocket sta ...

which was used to conduct eight

orbit In celestial mechanics, an orbit is the curved trajectory of an object such as the trajectory of a planet around a star, or of a natural satellite around a planet, or of an artificial satellite around an object or position in space such as a p ...

al launches between 1972 and 1975. It was a member of the

Delta Delta commonly refers to: * Delta (letter) (Δ or δ), a letter of the Greek alphabet * River delta, at a river mouth * D ( NATO phonetic alphabet: "Delta") * Delta Air Lines, US * Delta variant of SARS-CoV-2 that causes COVID-19 Delta may also ...

family of rockets. Several variants existed, differentiated by a four digit numerical code. Delta 1000 was developed by

McDonnell Douglas McDonnell Douglas was a major American aerospace manufacturing corporation and defense contractor, formed by the merger of McDonnell Aircraft and the Douglas Aircraft Company in 1967. Between then and its own merger with Boeing in 1997, it produ ...

company (now —

Boeing The Boeing Company () is an American multinational corporation that designs, manufactures, and sells airplanes, rotorcraft, rockets, satellites, telecommunications equipment, and missiles worldwide. The company also provides leasing and product ...

) in 1972. The same first stage and boosters were used on all variants. The first stage was an

Extended Long Tank Thor Extension, extend or extended may refer to: Mathematics Logic or set theory * Axiom of extensionality * Extensible cardinal * Extension (model theory) * Extension (predicate logic), the set of tuples of values that satisfy the predicate * E ...

, a further stretched version of the

Long Tank Thor Long may refer to: Measurement * Long, characteristic of something of great time, duration * Long, characteristic of something of great length * Longitude (abbreviation: long.), a geographic coordinate * Longa (music), note value in early music ...

used on earlier versions, itself derived from the

Thor Thor (; from non, Þórr ) is a prominent god in Germanic paganism. In Norse mythology, he is a hammer-wielding æsir, god associated with lightning, thunder, storms, sacred trees and groves in Germanic paganism and mythology, sacred groves ...

missile. Four, six or nine

Castor-2 The Castor family of solid-fuel rocket stages and boosters built by Thiokol (now Northrop Grumman) and used on a variety of launch vehicles. They were initially developed as the second-stage motor of the Scout rocket. The design was based on the ...

solid rocket boosters were attached to increase thrust at lift-off. These improvements permitted the Delta 1000 series to lift 1,835 kg (4,045 lbs) to LEO or 635 kg (1,400 lbs) to GTO. The nickname "Straight-Eight" comes from the fact that its second stage variants had the same 8 ft. (2.4 m) diameter as the first stage; previous Delta second stages were smaller in diameter. Two different second stages were flown, depending on the variant: * The Delta-F second stage, featuring the Aerojet

AJ10 The AJ10 is a hypergolic rocket engine manufactured by Aerojet Rocketdyne (previously Aerojet). It has been used to propel the upper stages of several launch vehicles, including the Delta II and Titan III. Variants were and are used as the servi ...

-118G engine, was flown on three launches, with

Explorer 47 Explorer 47 (IMP-H or IMP-7), was a NASA satellite launched as part of Explorer program. Explorer 47 was launched on 23 September 1972 from Cape Canaveral, Florida, with a Thor-Delta 1604. Explorer 47 was the ninth overall launch of the Inter ...

, 50 and 51; the Aerojet engine was flown for the (

Anik A1 Anik may refer to: * Anik (satellite), satellites launched by Canadian telecommunications company Telesat * Anik, Iran, a village in South Khorasan Province, Iran * Anik Mountain * Anik Bissonnette, a Canadian ballet dancer * Anik Jean (born 1977) ...

) satellite launch (mistakenly marked as xx1x in Delta 1000 series) * The

Delta-P The Delta-P is an American rocket upper stage, stage, developed by McDonnell Douglas and TRW, first used on November 10, 1972 as the second stage for the Delta 1000 series. It continued to serve as the second stage for subsequent Delta 2000 and ...

second stage, featuring the new TRW

TR-201 The TR-201 or TR201 is a hypergolic pressure-fed rocket engine used to propel the upper stage of the Delta rocket, referred to as Delta-P, from 1972 to 1988. The rocket engine uses Aerozine 50 as fuel, and as oxidizer. It was developed in the ...

engine, was used for two launches each in 1973 and 1975. Some flights used a third stage, either the Thiokol

Star-37D The Star is a family of US solid-propellant rocket motors originally developed by Thiokol and used by many space propulsion and launch vehicle stages. They are used almost exclusively as an upper stage, often as an apogee kick motor. Three Star 3 ...

Star-37E The Star is a family of US solid-propellant rocket motors originally developed by Thiokol and used by many space propulsion and launch vehicle stages. They are used almost exclusively as an upper stage, often as an apogee kick motor. Three Star 3 ...

, for launches beyond

low Earth orbit A low Earth orbit (LEO) is an orbit around Earth with a period of 128 minutes or less (making at least 11.25 orbits per day) and an eccentricity less than 0.25. Most of the artificial objects in outer space are in LEO, with an altitude never mor ...

. One probe launched by the Delta 1000 series, Delta 1913, was

Explorer 49 Explorer 49 (also called Radio Astronomy Explorer-2, RAE-B) was a NASA satellite launched on 10 June 1973, for long wave radio astronomy research. It had four X-shaped antenna elements, which made it one of the largest spacecraft ever built. ...

that was placed into lunar orbit on 10 June 1973. Delta 1000 rockets were launched from Space Launch Complex 2W at

Vandenberg AFB Vandenberg Space Force Base , previously Vandenberg Air Force Base, is a United States Space Force Base in Santa Barbara County, California. Established in 1941, Vandenberg Space Force Base is a space launch base, launching spacecraft from th ...

and Launch Complex 17B at

Cape Canaveral , image = cape canaveral.jpg , image_size = 300 , caption = View of Cape Canaveral from space in 1991 , map = Florida#USA , map_width = 300 , type =Cape , map_caption = Location in Florida , location ...

. All eight (1972-1975) launches were successful. Launching from LC-17B was had resulted successful removal of the exploitor-47 spacecraft for the study of the Earth's magnetosphere. During the first stage a carrier rocket was used in the modification of Delta-1604 with the onboard number 579/D90. The Japanese

N-II N-II was the former name for the Route Nacional from Madrid Madrid ( , ) is the capital and most populous city of Spain. The city has almost 3.4 million inhabitants and a metropolitan area population of approximately 6.7 million ...

and H-I launch vehicles used the same Extended Long Tank Thor first stage. For the second stage, the N-II used the Delta-F while the H-I had the Japanese

LE-5 The LE-5 liquid rocket engine and its derivative models were developed in Japan to meet the need for an upper stage propulsion system for the H-I and H-II series of launch vehicles. It is a bipropellant design, using LH and LOX. Primary design ...

engine which used liquid hydrogen and oxygen.

References

Delta (rocket family) {{rocket-stub