|   A Transtage | |
| Manufacturer | Martin Marietta | 
|---|---|
| Country of origin | United States | 
| Used on | Titan III | 
| General characteristics | |
| Height | 4.57 meters (15.0 ft) | 
| Diameter | 3.05 meters (10.0 ft) | 
| Gross mass | 12,247 kilograms (27,000 lb) | 
| Engine details | |
| Powered by | 2 AJ10-138 | 
| Maximum thrust | 8,000 lbf (36 kN) each [1] | 
| Specific impulse | 311 seconds (3.05 km/s) | 
| Burn time | 440 seconds | 
| Propellant | Aerozine 50 / N2O4 | 
Transtage, given the United States Air Force designation SSB-10A, was an American upper stage used on Titan III rockets, developed by Martin Marietta and Aerojet.
 
 Transtage was developed in anticipation of a requirement to launch military payloads to geostationary orbit; a contract for development of the stage was issued on 20 August 1962. [2] Transtage used a pressure-fed two-chamber configuration, using Aerozine 50 fuel and nitrogen tetroxide as oxidizer; the thrust chambers were gimbaled for steering and each produced 8,000 lbf (36 kN) of thrust. [3] The design specification required up to three restarts during the first six hours of a mission. [4]
Forty-seven Titan III launches are known to have used Transtage upper stages; [5] of those, three are known to have suffered launch failures. [6] The first launch, boosted by a Titan IIIA, occurred on 1 September 1964; [7] the Transtage failed to pressurize, resulting in premature engine cutoff, and a failure to reach orbit. [6] The second launch, on 10 December, was successful, and all ensuing launches used the Titan IIIC launch vehicle. The last launch of a Transtage was on 4 September 1989, boosted by a Titan 34D rocket. [6]