![]() Delta L before the failed attempt to launch Pioneer E | |
Has use | Expendable launch system |
---|---|
Country of origin | USA |
Size | |
Stages |
|
Launch history | |
Status | Retired |
Launch sites | Cape Canaveral LC-17A Vandenberg SLC-2E |
Total launches | 2 |
Success(es) | 1 |
Failure(s) | 1 |
First flight | 27 August 1969 |
Last flight | 31 January 1972 |
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.
The Delta L was a three-stage rocket. The first stage was a Long Tank Thor, a stretched version of the Thor missile, augmented by three Castor-2 solid rocket boosters. The second stage was the Delta E. 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. A defective valve caused plumbing in the hydraulics system to rupture and leak fluid, causing first-stage engine gimbaling to fail around 2+1⁄2 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 nor the TETR [1] payloads achieved orbit. The second, and final, Delta L launch was from Space Launch Complex 2E at the Vandenberg Air Force Base, on 31 January 1972. It successfully placed the HEOS-2 satellite into a highly elliptical orbit. [2] [3]
Delta is an American versatile family of expendable launch systems that has provided space launch capability in the United States since 1960. Japan also launched license-built derivatives from 1975 to 1992. More than 300 Delta rockets have been launched with a 95% success rate. Only the Delta IV Heavy rocket remains in use as of November 2020. Delta rockets are currently manufactured and launched by the United Launch Alliance.
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Intelsat III F-1 was a communications satellite intended to be operated by Intelsat. Launched towards geostationary orbit in 1968 it failed to achieve orbit.