Delta 4000

This article is about the rocket designated Delta 4000 under the old designation system. For the new system, see Delta IV.

Delta 4000 series

Launch of a Delta 4925
Function	Expendable launch system
Country of origin	United States
Launch history
Status	Retired
Launch sites	Canaveral LC-17B
Total launches	2
Successes	2
First flight	28 August 1989
Last flight	12 June 1990

The Delta 4000 series was an American expendable launch system which was used to conduct two orbital launches in 1989 and 1990. It was a member of the Delta family of rockets. Although several variants were put forward, only the Delta 4925 was launched. The designations used a four digit numerical code to store information on the configuration of the rocket. It was built from a combination of spare parts left over from earlier Delta rockets, which were being retired, and parts from the Delta II 6000-series, which was just entering service.

The first stage was the MB-3-III powered Extended Long Tank Thor, previously flown on the 1000-series. Nine Castor-4A solid rocket boosters were attached to increase thrust at lift-off, replacing the less powerful Castor-4 boosters used on the 3000 series. The Delta-K was used as a second stage. A Star-48B PAM-D was used as a third stage, to boost payloads into geosynchronous transfer orbit.

Both Delta 4000 launches occurred from Launch Complex 17B at Cape Canaveral. The first launched Marco Polo 1 for BSkyB, and the second launched INSAT 1D for the Indian Space Research Organisation. Both were successful.