The Delta L, Thor-Delta L, or Thrust-Augmented Long Tank Thor-Delta was a US

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 ...

used to launch the Pioneer E and TETR satellites in 1969 (failed) and HEOS satellite in 1972. 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. The Delta L was a three-stage rocket. The first stage was a

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 ...

, a stretched version of 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, augmented by three

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 booster A solid rocket booster (SRB) is a large solid propellant motor used to provide thrust in spacecraft launches from initial launch through the first ascent. Many launch vehicles, including the Atlas V, SLS and space shuttle, have used SRBs to give ...

s. The second stage was the

Delta E The Delta E, or Thor-Delta E was an American expendable launch system used for twenty-three orbital launches between 1965 and 1971. It was a member of the Delta family of rockets. The first stage was a Thor missile in the DSV-2C configuration, ...

. An FW-1D solid rocket motor was used as the third stage. The first launch of the Delta L took place on 27 August 1969, from Launch Complex 17A at the

Cape Canaveral Air Force Station Cape Canaveral Space Force Station (CCSFS) is an installation of the United States Space Force's Space Launch Delta 45, located on Cape Canaveral in Brevard County, Florida. Headquartered at the nearby Patrick Space Force Base, the statio ...

. A defective valve caused plumbing in the hydraulics system to rupture and leak fluid, causing first-stage engine gimbaling to fail around minutes into launch. The stage completed its burn successfully, but threw the second stage far off course. Orbital velocity could not be achieved, and Range Safety sent the destruct command at T+383 seconds. Neither the

Pioneer E ''Pioneer 6'', ''7'', ''8'', and ''9'' were space probes in the Pioneer program, launched between 1965 and 1969. They were a series of solar-orbiting, spin-stabilized, solar cell- and battery-powered satellites designed to obtain measurements ...

nor the TETR payloads achieved orbit. The second, and final, Delta L launch was from Space Launch Complex 2E at the

Vandenberg Air Force Base Vandenberg may refer to: * Vandenberg (surname), including a list of people with the name * USS General Harry Taylor (AP-145), USNS ''General Hoyt S. Vandenberg'' (T-AGM-10), transport ship in the United States Navy, sank as an artificial reef in K ...

, on 31 January 1972. It successfully placed the HEOS-2 satellite into a

highly elliptical orbit A highly elliptical orbit (HEO) is an elliptic orbit with high eccentricity, usually referring to one around Earth. Examples of inclined HEO orbits include Molniya orbits, named after the Molniya Soviet communication satellites which used them, ...

References

Delta (rocket family) {{rocket-stub