Delta 1000 series
Delta 1910 launching OSO-8
FunctionExpendable launch system
Country of originUnited States
Launch history
Launch sitesCanaveral LC-17B
Vandenberg SLC-2W
Total launches8
First flight23 September 1972
Last flight21 June 1975

The Delta 1000 series (also referred to as Straight-Eight) was an American expendable launch system which was used to conduct eight orbital launches between 1972 and 1975. It was a member of the Delta family of rockets. Several variants existed, differentiated by a four digit numerical code. Delta 1000 was developed by McDonnell Douglas company (now — Boeing) in 1972.

The same first stage and boosters were used on all variants. The first stage was an Extended Long Tank Thor, a further stretched version of the Long Tank Thor used on earlier versions, itself derived from the Thor missile. Four, six or nine Castor-2 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:

Some flights used a third stage, either the Thiokol Star-37D or Star-37E, for launches beyond low Earth orbit. One probe launched by the Delta 1000 series, Delta 1913, was Explorer 49 that was placed into lunar orbit on 10 June 1973.

Delta 1000 rockets were launched from Space Launch Complex 2W at Vandenberg AFB and Launch Complex 17B at Cape Canaveral. All eight (1972-1975) launches were successful.

The Japanese N-II 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 engine which used liquid hydrogen and oxygen.[2][3]


  1. ^ Kyle, Ed (9 April 2010). "Delta 1000 series". Space Launch Report.
  2. ^ Wade, Mark. "Delta". Archived from the original on 2008-07-24.
  3. ^ Krebs, Gunter. "Thor Family". Gunter's Space Page. Archived from the original on 2007-08-06. Retrieved 2021-12-21.