Titan 23G

The Titan 23G, Titan II(23)G, Titan 2(23)G or Titan II SLV was an American expendable launch system derived from the LGM-25C Titan II intercontinental ballistic missile. Retired Titan II missiles were converted by Martin Marietta, into which the Glenn L. Martin Company, which built the original Titan II, had merged. It was used to carry payloads for the United States Air Force, NASA and NOAA. Thirteen were launched from Space Launch Complex 4W at the Vandenberg Air Force Base between 1988 and 2003.[1]

Titan 23G
The first Titan 23G prior to launch
FunctionExpendable launch system
ManufacturerMartin Marietta
Country of originUnited States
Height31.4 meters (103 ft)
Diameter3.05 meters (10.0 ft)
Mass117,020 kilograms (257,980 lb)
StagesTwo or Three
Payload to LEO3,600 kilograms (7,900 lb)
Payload to Polar LEO2,177 kilograms (4,799 lb)
Payload to HCO227 kilograms (500 lb)
Associated rockets
Launch history
Launch sitesVandenberg SLC-4W
Total launches13
First flight5 September 1988
Last flight18 October 2003
Notable payloadsClementine
First stage
EnginesLR-87 (one engine with two combustion chambers)
Thrust1,900 kilonewtons (430,000 lbf)
Specific impulse258 sec
Burn time156 seconds
Second stage
Engines1 LR-91
Thrust445 kilonewtons (100,000 lbf)
Specific impulse316 sec
Burn time180 seconds
Third stage (Optional) – Star-37XFP-ISS
Engines1 Solid
Thrust38.03 kilonewtons (8,550 lbf)
Specific impulse290 sec
Burn time67 seconds
Third stage (Optional) – Star-37S
Engines1 Solid
Specific impulse287 sec

Titan 23G rockets consisted of two stages burning liquid propellant. The first stage was powered by one Aerojet LR87 engine with two combustion chambers and nozzles, and the second stage was propelled by an LR91. On some flights, solid upper stages were flown, usually the Star-37XFP-ISS; however, the Star-37S was also used.[1]

A contract to refurbish fourteen Titan II missiles to the Titan 23G configuration was awarded to Martin Marietta in January 1986. The first launch occurred on 5 September 1988, carrying a classified payload for the US National Reconnaissance Office. Thirteen were launched, with the fourteenth going to the Evergreen Aviation Museum.[2] The final flight occurred on 17 October 2003, carrying a DMSP satellite.[3]

During refurbishment, the forward structure of the second stage was modified with the addition of a payload attachment fitting to attach the payload to the rocket, and installing a payload fairing to protect it during launch. The engines were refurbished, and the rockets' guidance and control systems were upgraded by Delco Electronics.

The former Titan IIIB pad at Vandenberg, SLC-4W, was modified to accommodate the Titan 23G, and was used for all thirteen launches.


All launches of Titan II(23)G rockets took place from Space Launch Complex 4W at Vandenberg Air Force Base.

Date/Time (UTC) Serial number Third Stage Payload Outcome Remarks
Rocket Stages
5 September 1988
G-1 B-98/56 None USA-32 (Bernie) Successful
6 September 1989
G-2 B-75/99 None USA-45 (Bernie) Successful Spacecraft failed immediately after launch
25 April 1992
G-3 B-102 None USA-81 (Bernie) Successful
5 October 1993
G-5 B-65 Star-37XFP-ISS Landsat 6 Failure[4] Star-37 failure, failed to achieve orbit[5]
25 January 1994
G-11 B-89/67 None Clementine
4 April 1997
G-6 B-106 Star-37S-ISS USA-131 (DMSP-5D2 F-14) Successful
13 May 1998
G-12 B-84/80 Star-37XFP-ISS NOAA-15 (NOAA-K) Successful Included oxygen tank from Titan II B-72
20 June 1999
G-7 B-99/75 None QuikSCAT Successful
12 December 1999
G-8 B-94/44 Star-37XFP-ISS USA-147 (DMSP-5D3 F-15) Successful
21 September 2000
G-13 B-96/39 Star-37XFP-ISS NOAA-16 (NOAA-L) Successful
24 June 2002
G-14 B-71/72 Star-37XFP-ISS NOAA-17 (NOAA-M) Successful Included oxygen tank from Titan II B-92
6 January 2003
G-4 B-105 None Coriolis Successful
18 October 2003
G-9 B-107 Star-37XFP-ISS USA-172 (DMSP-5D3 F-16) Successful Final Titan II launch

A fourteenth rocket, G-10, based on Titan II B-108, but incorporating an oxygen tank from B-80, was not launched and is preserved at the Evergreen Aviation & Space Museum in McMinnville, Oregon. The remaining 42 Titan II missiles were stored at Davis-Monthan AFB with most being broken up for salvage. Four were transferred to museums.

See also


  1. Krebs, Gunter. "Titan-2". Gunter's Space Page. Retrieved 2009-04-29.
  2. Kyle, Ed (2009-04-14). "Titan 23G Data Sheet". Space Launch Report. Retrieved 2009-04-29.
  3. Wade, Mark. "Titan". Encyclopedia Astronautica. Retrieved 2009-04-29.
  4. Kyle, Ed. "Titan Launch History". Space Launch Report. p. 3. Retrieved 24 January 2014.
  5. Wade, Mark. "Landsat 6". Encyclopedia Astronautica. Retrieved 24 January 2014.
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