Encyclopedia Astronautica
Home - Search - Browse - Alphabetic Index: 0- 1- 2- 3- 4- 5- 6- 7- 8- 9
A- B- C- D- E- F- G- H- I- J- K- L- M- N- O- P- Q- R- S- T- U- V- W- X- Y- Z

Gemini Agena Target Vehicle
Part of Agena Family
Agena Target Vehicle
Agena Target Vehicle
Agena Target Docking Vehicle
Credit: © Mark Wade
American modification of the Agena-D upper stage for use as a docking target and space tug for Gemini.

Status: Operational 1965. First Launch: 1965-10-25. Last Launch: 1966-11-11. Number: 6 . Gross mass: 3,260 kg (7,180 lb). Height: 7.93 m (26.01 ft). Diameter: 1.52 m (4.98 ft).

To provide the Gemini spacecraft with a rendezvous and docking target, Agena D rocket stages were modified with the addition of a docking collar, status panel display, and restart capabilities for the Gemini program. After docking, the Agena had sufficient fuel reserves to boost the Gemini into high earth orbits, to the edge of the Van Allen radiation belts.

The Gemini-Agena Target Vehicle design was an adaptation of the basic Agena-D vehicle using the alternate Model 8247 rocket engine and additional program-peculiar equipment required for the Gemini mission. This GATV was divided into:

  • The program-peculiar forward auxiliary section. This section consisted of the auxiliary equipment rack, the McDonnell Aircraft Company-furnished docking-adapter module, and the clamshell nose shroud.
  • The Agena-D forward and mid-body sections. The Agena-D forward section housed the main equipment bay, and the mid-body contained the main fuel and oxidizer tanks which supplied propellants through a feed and load system for the main engine. (3) the program-peculiar aft section. The Model 8247 multi-start main engine and the smaller Model 8250 maneuvering and ullage orientation engines were located in this section.

Orbital length of the GATV was approximately 26 feet. Vehicle weight-on-orbit was approximately 7200 lb. This weight included propellants still remaining in the main tanks and available for Model 8247 engine operation after the Agena achieved orbit.

The Gemini-ATV propulsion system consisted of the following:

  • Model 8247 rocket engine, also known as XLR-81-BA-13, and its controls, mount, gimbals, and titanium nozzle extension
  • Pyrotechnically operated helium-control valve (POHCV) and associated pressurization plumbing
  • Fuel and oxidizer feed and load system, including propellant tanks, vents, and fill quick disconnects
  • Propellant isolation valves (PIV's)
  • All associated pyro devices and solid-propellant rockets.

The XLR-81-BA-13 engine thrust chamber was an 80-percent bell-shape with an expansion ratio of 45:1. This thrust chamber assembly performed satisfactorily throughout a gimbaling orientation of plus 5 deg in a square pattern from the associated planes, with a gimbal acceleration of 30 rads/sec/sec. The nozzle was regeneratively cooled up to the point at which the area ratio was 13.3: I. The remaining portion of the nozzle (13.3:1 to 45:1) was a radiation-cooled titanium extension.

The propulsion system was designed to inject the GATV into an orbital path which has an altitude varying between 161 nautical miles (nm) and 87 nm when measured at a latitude of 28. 34 deg. A minimum of five main-engine burns were available to complete the mission requirements; one burn was required for injection into orbit and four subsequent burns were available to perform orbital plane and phase changes, as required and selected from ground stations or from the spacecraft. All launches took place from AMR Pad 14.

Once the GATV was in orbit, the PPS provided the thrust necessary for the following maneuvers :

  • Adjusting the orbits so that they were coplanar and making the radius of one apside of the Agena orbit equal to the rendezvous radius
  • Circularizing the Agena at the rendezvous radius and proceeding to an inertial location which was a point lying on the line of the apsides of the catch-up orbit
  • At the initial location of the injection point, transferring the Agena to a catch-up orbit for placing the vehicle at the rendezvous point when specified.

The XLR-8I-BA-13 was a liquid bi-propellant rocket engine with a minimum capability of five starts and a demonstrated capability of fifteen starts under vacuum conditions. This rocket engine consisted of the following major components:

  • Thrust-chamber assembly
  • Multiple-restart assembly
  • Turbine-pump assembly
  • Overspeed shutdown electronic-gate and cable assembly
  • Turbine-exhaust duct
  • Propellant manifolds
  • Thrust-chamber nozzle extension

Fuel used was unsymmetrical dimethylhydrazine (UDMH); oxidizer used was inhibited red fuming nitric acid (IRFNA). The propulsion system provided the thrust necessary to place the GATV into a selected orbit and to accomplish major orbital changes. A minimum of five starts was available for performing these maneuvers.

The Gemini-ATV Status Panel (ASP), was mounted on the forward end of the Target Docking Adapter of the Agena Target Vehicle where it was visible to the astronauts in the Gemini spacecraft during and after the docking maneuver. The panel displayed information on the status and safety of the Agena propulsion, guidance, electrical power, and docking systems. Originally, only eight Agena parameters were to be displayed in the Gemini spacecraft; however, the number of parameters increased to the point that the spacecraft no longer had the space or weight capability to accommodate them. Accordingly, the panel was placed on the Target Docking Adapter. The ASP system consisted of a display panel with nine display lights and three analog dials and the necessary circuitry which was distributed throughout the Gemini-ATV. When not in use, this system was normally de-energized in order to save power; however, the PPS and SPS Time Remaining Clocks were energized whenever the PPS or SPS engines fire. Three of the twelve parameters displayed on the ASP panel, indicated PPS status and three indicated SPS status. The Primary Propulsion System displays were as follows:

  • PPS Burn Time Remaining Clock
  • "MAIN" Red Light
  • "MAIN" Green Light

The Secondary Propulsion System displays were as follows:

  • SPS Burn Time Remaining Clock
  • "SEC HI" Green Light
  • "SEC LO" Green Light

Requirements received from the astronauts stated that a dimming circuit must be added to the ASP system, because the panel lights were found to be too bright when the spacecraft docked with the GATV on the night side of the earth. Consequently, a dimming circuit was added to reduce or increase the brightness to the desired level. The dimming circuit functions on all lights except MAIN Red which was always bright when "ON". In order to improve reliability, two lamps were incorporated in each indicator light.

Family: Space Tugs. People: McDonnell. Country: USA. Spacecraft: Gemini. Launch Vehicles: Atlas, Atlas SLV-3 Agena D. Launch Sites: Cape Canaveral, Cape Canaveral LC14. Agency: NASA. More at: 6517. Bibliography: 126, 2, 205, 2193, 2194, 2195, 2196, 2197, 2198, 2199, 2200, 2201, 2202, 2203, 26, 278, 4365, 6.


Photo Gallery

Gemini-AgenaGemini-Agena
Gemini docked to Agena
Credit: © Mark Wade


Gemini 10 Agena TargGemini 10 Agena Targ
Credit: Manufacturer Image



1965 October 25 - . 15:00 GMT - . Launch Site: Cape Canaveral. Launch Complex: Cape Canaveral LC14. LV Family: Atlas. Launch Vehicle: Atlas SLV-3 Agena D. FAILURE: Exploded 6 minutes after takeoff. Failure.. Failed Stage: U.
  • Gemini 6 Agena Target - . Payload: TDA-2. Mass: 3,261 kg (7,189 lb). Nation: USA. Agency: NASA. Program: Gemini. Class: Manned. Type: Manned logistics spacecraft. Flight: Gemini 6, Gemini 7. Spacecraft Bus: Agena. Spacecraft: Gemini Agena Target Vehicle. Decay Date: 1965-10-25 . The Agena target vehicle failed to reach orbit. Gemini 6, awaiting launch, was cancelled. In the ashes of this setback, the idea of launching Gemini 6 to rendezvous with Gemini 7 was born..

1966 March 16 - . 15:00 GMT - . Launch Site: Cape Canaveral. Launch Complex: Cape Canaveral LC14. LV Family: Atlas. Launch Vehicle: Atlas SLV-3 Agena D.
  • Gemini 8 Agena Target - . Payload: TDA 3/Agena D 5003 GATV. Mass: 3,175 kg (6,999 lb). Nation: USA. Agency: NASA Houston. Program: Gemini. Class: Manned. Type: Manned logistics spacecraft. Flight: Gemini 8. Spacecraft Bus: Agena. Spacecraft: Gemini Agena Target Vehicle. Decay Date: 1967-09-15 . USAF Sat Cat: 2104 . COSPAR: 1966-019A. Apogee: 299 km (185 mi). Perigee: 285 km (177 mi). Inclination: 28.9000 deg. Period: 90.40 min. Target vehicle for Gemini 8..

1966 April 12 - .
  • Gemini Agena target vehicle 5005 completed modification and final assembly with the installation of a number of electrical and electronic components for which it had been waiting. - . Nation: USA. Spacecraft Bus: Agena. Spacecraft: Gemini Agena Target Vehicle.

    These included the guidance module, flight control junction box, and flight electronics package. The vehicle was transferred to test complex C-10 at Sunnyvale to begin Vehicle Systems Tests. Preliminary test tasks were completed by April 23, with preliminary inspection on April 26-27.


1966 May 17 - . 15:15 GMT - . Launch Site: Cape Canaveral. Launch Complex: Cape Canaveral LC14. LV Family: Atlas. Launch Vehicle: Atlas SLV-3 Agena D. FAILURE: Control system failure.. Failed Stage: G.
  • Gemini 9 Agena Target - . Payload: TDA 5. Mass: 3,248 kg (7,160 lb). Nation: USA. Agency: NASA. Program: Gemini. Class: Manned. Type: Manned logistics spacecraft. Flight: Gemini 9. Spacecraft Bus: Agena. Spacecraft: Gemini Agena Target Vehicle. Decay Date: 1966-05-17 .

    The Gemini 9 mission was scrubbed when the Atlas booster launched from Cape Canaveral failed to place the Gemini Agena Target Vehicle (GATV) in its planned circular orbit. A malfunction of the number 2 booster engine of the Atlas caused both the Atlas and Agena to fall into the ocean. The Gemini 9-Atlas/Agena mission was later rescheduled to 1 June using the Augmented Target Docking Adapter (ATDA).


1966 July 18 - . 20:39 GMT - . Launch Site: Cape Canaveral. Launch Complex: Cape Canaveral LC14. LV Family: Atlas. Launch Vehicle: Atlas SLV-3 Agena D.
  • Gemini 10 Agena Target - . Payload: TDA 1A/Agena D 5005 GATV. Mass: 3,175 kg (6,999 lb). Nation: USA. Agency: NASA Houston. Program: Gemini. Class: Manned. Type: Manned logistics spacecraft. Flight: Gemini 10. Spacecraft Bus: Agena. Spacecraft: Gemini Agena Target Vehicle. Decay Date: 1966-12-29 . USAF Sat Cat: 2348 . COSPAR: 1966-065A. Apogee: 296 km (183 mi). Perigee: 290 km (180 mi). Inclination: 28.9000 deg. Period: 90.40 min.

    An Air Force Titan Gemini Launch Vehicle placed the Gemini 10 (GT-10) spacecraft into orbit for the three-day mission of Astronauts John Young and Michael Collins. Rendezvous and docking were accomplished with the Gemini Agena Target Vehicle (GATV) that had been launched from Cape Kennedy aboard an Atlas Booster just ahead of GT-10. Using the GATV-10 Primary Propulsion System (PPS), the docked vehicles achieved a manned-flight altitude record of 476 miles. Reentry was accomplished on 21 July and recovery was made 544 miles east of Cape Canaveral. Space craft engaged in investigation of spaceflight techniques and technology (US Cat A).


1966 September 12 - . 13:05 GMT - . Launch Site: Cape Canaveral. Launch Complex: Cape Canaveral LC14. LV Family: Atlas. Launch Vehicle: Atlas SLV-3 Agena D.
  • Gemini 11 Agena Target - . Payload: TDA 6/Agena D 5006 GATV. Mass: 3,175 kg (6,999 lb). Nation: USA. Agency: NASA Houston. Program: Gemini. Class: Manned. Type: Manned logistics spacecraft. Flight: Gemini 11. Spacecraft Bus: Agena. Spacecraft: Gemini Agena Target Vehicle. Decay Date: 1966-12-30 . USAF Sat Cat: 2414 . COSPAR: 1966-080A. Apogee: 298 km (185 mi). Perigee: 298 km (185 mi). Inclination: 28.8000 deg. Period: 90.40 min. Docking target for Gemini 11..

1966 November 11 - . 19:07 GMT - . Launch Site: Cape Canaveral. Launch Complex: Cape Canaveral LC14. LV Family: Atlas. Launch Vehicle: Atlas SLV-3 Agena D.
  • Gemini 12 Agena Target - . Payload: TDA 7A/Agena D 5001R GATV. Mass: 3,175 kg (6,999 lb). Nation: USA. Agency: NASA Houston. Program: Gemini. Class: Manned. Type: Manned logistics spacecraft. Flight: Gemini 12. Spacecraft Bus: Agena. Spacecraft: Gemini Agena Target Vehicle. Decay Date: 1966-12-23 . USAF Sat Cat: 2565 . COSPAR: 1966-103A. Apogee: 310 km (190 mi). Perigee: 243 km (150 mi). Inclination: 28.8000 deg. Period: 89.90 min. Docking target for Gemini 12..


Home - Search - Browse - Alphabetic Index: 0- 1- 2- 3- 4- 5- 6- 7- 8- 9
A- B- C- D- E- F- G- H- I- J- K- L- M- N- O- P- Q- R- S- T- U- V- W- X- Y- Z
© 1997-2016 Mark Wade - Contact
© / Conditions for Use