Lockheed Martin (General Dynamics) SSB-8 Centaur
The Centaur upper stage, fuelled by liquid oxygen and liquid hydrogen, was initially developed by General Dynamics to place military communications satellites into orbit. When the programme was cancelled, the launcher was handed over for civilian use by NASA. In 1994 the rights to the Centaur upper stage were sold to Martin Marietta, which in 1995 merged with Lockheed to become Lockheed Martin. Current prime contractor for Centaur is United Launch Alliance, a joint-venture of Boeing and Lockheed Martin, founded in 2006.
The Centaur upper stage was first used on 27 November 1963 after a failure on 8 May 1962. The stage was also known by its military designation SSB-8A although this designation was probably restricted to military launches.
Atlas uses
The Centaur upper stage was extensively used with the basic Atlas launch vehicle in a range of versions. It is still being used in the Atlas V.
| Type | Length | Diameter | Engine | Thrust | Used with | # |
|---|---|---|---|---|---|---|
| Centaur A | 9.10 m | 3.05 m | 2 P&W RL-10A-1 | 133,453 N | Atlas Centaur A | 1 |
| Centaur B | 9.10 m | 3.05 m | 2 P&W RL-10A-3 | 133,453 N | Atlas Centaur B | 1 |
| Centaur C | 9.10 m | 3.05 m | 2 P&W RL-10A-3 | 133,453 N | Atlas Centaur C | 3 |
| Centaur D | 9.10 m | 3.05 m | 2 P&W RL-10A-3-1 or -3 | 131,227 N | Atlas Centaur D | 17 |
| Centaur D1A | 9.10 m | 3.05 m | 2 P&W RL-10A-3-3 | 131,227 N | Atlas Centaur D1A | 6 |
| Centaur D1AR | 9.10 m | 3.05 m | 2 P&W RL-10A-3-3 | 131,227 N | Atlas Centaur D1AR | 33 |
| Centaur I | 9.10 m | 3.05 m | 2 P&W RL-10A-3-3A | 146,810 N | Atlas I | 11 |
| Centaur II | 10.06 m | 3.05 m | 2 P&W RL-10A-3-3A | 146,810 N | Atlas II | 10 |
| Centaur IIA | 10.06 m | 3.05 m | 2 P&W RL-10A-4 | 185,019 N | Atlas IIA, Atlas IIAS | 53 |
| Centaur IIIA | 10.06 m | 3.05 m | 1 P&W RL-10A-4-1 | 99,158 N | Atlas IIIA | 2 |
| Centaur IIIB DEC | 11.68 m | 3.05 m | 2 P&W RL-10A-4-2 | 198,317 N | Atlas IIIB | 1 |
| Centaur IIIB SEC | 11.68 m | 3.05 m | 1 P&W RL-10A-4-2 | 99,158 N | Atlas IIIB | 3 |
| Centaur III(5) DEC | 11.68 m | 3.05 m | 2 P&W RL-10A-4-2 | 198,317 N | Atlas V | 3 * |
| Centaur III(5) SEC | 11.68 m | 3.05 m | 1 P&W RL-10A-4-2 | 99,158 N | Atlas V | 103 * |
| * as of 31 December 2025 |
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-sec.jpg) | |
| Photos: NASA | ||
| Centaur IIA | Centaur III(5) SEC | |
Titan uses
The Centaur was also used with the basic Titan IIIE and IV launch vehicles, in two versions.
| Type | Length | Diameter | Engine | Thrust | Used with | # |
|---|---|---|---|---|---|---|
| Centaur D1T | 9.60 m | 3.05 m | 2 P&W RL-10A-3-3 | 131,227 N | Titan IIIE Centaur | 7 |
| Centaur T | 9.00 m | 4.30 m | 2 P&W RL-10A-3A | 146,810 N | Titan 401A/B | 15 |
The Centaur D/E was a proposed version to be used with the Titan IIIBAS2 launch vehicle whilst the Centaur upper stage was also proposed for the Titan IIIL. Neither launch vehicle was developed beyond the initial design stages.
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| Photo: Author's collection |
| Centaur T |
Space Shuttle use
The Centaur G was a version proposed for use with the Space Shuttle. It was to have 2 Pratt & Whitney RL-10-3-3A engines and was to be built in a basic version with a length of 6.00 m and a diameter of 4.30 m, and a stretched version with a length of 9.00 m. Development of this version was not proceeded with.
Centaur 5
The Centaur 5 is a new and enlarged development, with a diameter of 5.4 m (17.7 ft) and two RL10C engines with a combined thrust of 214 kN (48000 lb). It is used as upper stage in the Vulcan-Centaur launch vehicle, and first flew on that rocket on 8 January 2024.
Main Sources (for updates in 2026)
[1] Gunter Krebs: Gunter's Space Page (launch lists)
Back to Directory of U.S. Military Rockets and Missiles, Appendix 3
Last Updated: 22 February 2026