Delta 1910 launching OSO-8
|Function||Expendable launch system|
|Country of origin||United States|
|Launch sites||Canaveral LC-17B|
|First flight||23 September 1972|
|Last flight||21 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.
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.