Thor-Agena A Credit - US Air Force Media Gallery

2 stage vehicle consisting of 1 x Thor DM-18A + 1 x Agena A

Manufacturer: Douglas. Launches: 16. Failures: 6. Success Rate: 62.50%. First Launch Date: 1959-01-21. Last Launch Date: 1960-09-13. Launch data is: complete. LEO Payload: 250 kg (550 lb). Apogee: 1,000 km (600 mi). Associated Spacecraft: KH-1. Liftoff Thrust: 667.200 kN (149,993 lbf). Total Mass: 53,130 kg (117,130 lb). Core Diameter: 2.44 m (8.00 ft). Total Length: 28.00 m (91.00 ft). Flyaway Unit Cost $: 10.730 million. in: 1985 unit dollars.

• Stage Number: 1. 1 x Stage: Thor DM-19. Gross Mass: 49,340 kg (108,770 lb). Empty Mass: 3,125 kg (6,889 lb). Thrust (vac): 758.711 kN (170,565 lbf). Isp: 282 sec. Burn time: 165 sec. Isp(sl): 248 sec. Diameter: 2.44 m (8.00 ft). Span: 2.44 m (8.00 ft). Length: 18.42 m (60.43 ft). Propellants: Lox/Kerosene. No Engines: 1. Engine: LR-79-7.

• Stage Number: 2. 1 x Stage: Agena A . Gross Mass: 3,790 kg (8,350 lb). Empty Mass: 885 kg (1,951 lb). Thrust (vac): 68.950 kN (15,501 lbf). Isp: 276 sec. Burn time: 120 sec. Isp(sl): 0 sec. Diameter: 1.52 m (4.98 ft). Span: 1.52 m (4.98 ft). Length: 4.73 m (15.51 ft). Propellants: Nitric acid/UDMH. No Engines: 1. Engine: Bell 8048. Other designations: RM-81. Status: Out of production. Historical Essay © Andreas Parsch

  Lockheed RM-81 Agena

  The Agena space vehicle was used in large numbers during the 1960s and 1970s as upper stage with SLV-2 Thor, SLV-3 Atlas and SLV-5 Titan boosters to launch a variety of military and civilian payloads into orbit. The Agena itself was actually the first general-purpose satellite, and formed the core for many operational satellites and experimental space vehicles. It is included in this missile directory, because the U.S. Air Force allocated the formal missile designator RM-81 to the Agena (see section on RM-81 Designation for details).

  In 1955, the U.S. Air Force began its Weapons System 117L program, calling for the development of a strategic satellite system. The initial primary goal of WS-117L was the development an orbital photo-reconnaissance platform, and in October 1956, Lockheed became prime contractor for the system. The core element of WS-117L was a new multipurpose spacecraft with boost and manoeuvering engines, which would act as the second stage of the launch vehicle as well as the carrier vehicle for the reconnaissance system. Lockheed's Agena spacecraft was built around the Bell XLR81 liquid-propellant rocket engine, and was initially known informally as Hustler, because the XLR81 was originally developed for a (later cancelled) rocket-powered weapons pod for the B-58 Hustler bomber. The first launch of a Thor-Agena combination in January 1959 was a failure, but on 28 February that year, Agena scored its first success when a Thor-Agena launcher placed the Discoverer 1 satellite into polar orbit.

  Agena A

  The first few Agenas, including the vehicle used in the Discoverer 1 launch, used a Bell XLR81-BA-3 rocket engine, but most vehicles of the initial Agena A series used an XLR81-BA-5 (Bell Model 8048). The engine had gimballed nozzles for pitch and yaw control, and could deliver a thrust of 68.9 kN (15500 lb) for up to 120 s.

  Launch Vehicle Combination	Number of Launches	First/Last Launch
  Thor (SLV-2) + Agena A	16	21-Jan-1959 / 13-Sep-1960
  Atlas (LV-3A) + Agena A	4	26-Feb-1960 / 31-Jan-1961
  Total for Agena A	20	21-Jan-1959 / 31-Jan-1961

  Launch summary for Agena A

  The Thor-Agena A launched the initial reconnaissance satellites of the CORONA (publicly named Discoverer) series (KH-1 system), while the Atlas-Agena A was used for the first two launches of both the Midas (Missile Detection And Surveillance) early-warning system and Samos (Satellite and Missile Observation System) ELINT satellite series.

  Agena B

  The Agena B had an improved XLR81-BA-7 engine (Bell Model 8081), which could be restarted in space, and was stretched to carry much more propellant, doubling the total burn time to 240 s. Both features greatly increased the versatility of the Agena vehicle. When launched into low orbits, the Agena B had plenty of fuel left for extensive orbital manoeuvers, an important requirement for a reconnaissance platform. Later models of the Agena B used a further improved XLR81-BA-9 (Bell Model 8096) engine, which (among other changes) increased the thrust to 71.1 kN (16000 lb) by using a different type of fuel.

  Launch Vehicle Combination	Number of Launches	First/Last Launch
  Thor (SLV-2) + Agena B	44*	26-Oct-1960 / 28-Aug-1964
  Thrust-Augmented Thor (SLV-2A/C) + Agena B	3*	29-Jun-1963 / 15-May-1966
  Atlas (LV-3A) + Agena B	28	12-Jul-1961 / 21-Mar-1965
  Atlas (SLV-3) + Agena B	1	9-Jun-1966
  Total for Agena B	76	26-Oct-1960 / 9-Jun-1966

  Launch summary for Agena B

  * Thor variant counts slightly differ between sources, but Thor-Agena total is not in question

  Most of the Thor-Agena B vehicles launched KH-series reconnaissance systems (all KH-2/3 CORONAs, and some satellites of the KH-4 CORONA and KH-5 ARGON series). The remainder included e.g. some ELINT systems of the Samos program. The Atlas-Agena B launched a variety of spacecraft, the major ones being Midas early-warning systems, Samos ELINT systems and Ranger space probes.

  Agena C

  The designation Agena C was reserved for a proposed enlarged variant, which was to have doubled the capability of the Agena B (most likely by doubling the fuel tank size). However, this version was not built.

  Agena D

  The majority of Agenas were of the final Agena D variant. This was essentially a "standardized" Agena B, which could accept a variety of payloads (in a conical payload section in the nose) and be fitted to Atlas, Thor or Titan launchers without changes to the basic Agena. The earlier Agena A/B vehicles were tailor-made for their respective payloads and launcher types. The Agena D launched a large number of military and scientific payloads, including e.g. the Gemini-Agena target vehicles used by NASA for space capsule docking experiments in 1966.

  Launch Vehicle Combination	Number of Launches	First/Last Launch
  Thor (SLV-2) + Agena D	22*	28-Jun-1962 / 31-May-1967
  Thrust-Augmented Thor (SLV-2A/C) + Agena D	60*	28-Feb-1963 / 17-Jan-1968
  LTTAT** (SLV-2G/H) + Agena D	22*	9-Aug-1966 / 16-Jul-71
  Thorad (SLV-2G/H) + Agena D	21*	18-May-1968 / 25-May-72
  Atlas (LV-3A) + Agena D	15	12-Jul-1963 / 20-Jul-1965
  Atlas (SLV-3) + Agena D	48	14-Aug-1964 / 5-Nov-1967
  Atlas (SLV-3A) + Agena D	12	4-Mar-1968 / 7-Apr-1978
  Atlas F + Agena D	1	27-Jun-1978
  Titan 3B å (SLV-5B)	29	29-Jul-1966 / 23-Oct-1970
  Titan 23B åå	2	21-Jan-1971 / 22-Apr-1971
  Titan 33B åå	3	21-Mar-1971 / 21-Aug-1973
  Titan 24B åå	23	12-Aug-1971 / 21-Aug-1973
  Titan 34B åå	11	10-Mar-1975 / 12-Feb-1987
  Total for Agena D	269	28-Jun-1962 / 12-Feb-1987

  Launch summary for Agena D

  * Thor variant counts slightly differ between sources, but Thor-Agena total is not in question
  ** LTTAT = Long-Tank Thrust-Augmented Thor (quoted by some sources as identical to Thorad)
  å Titan 3B was the designation for the Titan 3 + Agena D combination
  åå These derivatives of the Titan 3B are sometimes called 3(23)B, 3(33B), 3(24)B and 3(34)B, respectively.

  The majority of Agena D missions on Thor-type boosters launched KH-series reconnaissance systems, mostly CORONA (KH-4/4A/4B), but also ARGON (KH-5) and LANYARD (KH-6). Most of the initial Atlas-Agena D vehicles (LV-3A/SLV-3) launched GAMBIT satellites (KH-7 reconnaissance system) into orbit, but payloads also included the Mariner series of interplanetary probes and the GATV (Gemini-Agena Target Vehicle). The SLV-3A/Agena D was used to launch the CANYON and RHYOLITE/AQUACADE series of ELINT/SIGINT satellites into geostationary orbits.

  The Titan 3B/23B/24B series launched GAMBIT (KH-8 reconnaissance system) satellites, while the payloads of the larger Titan 33B/34B boosters consisted of JUMPSEAT SIGINT and SDS communications satellites.

  A total of 365 Agena vehicles of all types were launched into space by the U.S. Air Force and NASA between January 1959 and 12 February 1987, when the last Agena D was launched with a USAF payload (SDS communications satellite #7) as upper stage of a Titan 34B booster.

  RM-81 Designation

  In 1958 (or early 1959), the U.S. Air Force allocated the formal "Research Missile" designation RM-81 to the Agena space vehicle. The reasons for this remain unclear, but the USAF possibly needed to assign a designator for formal purposes and there was no better alternative at that time. USAF serial number listings show a total order of 341 Agenas, designated as XRM-81, RM-81, SRM-81 and SRM-81A. Because I cannot connect these four designators in any way to the documented basic Agena variants (Agena A/B/D), I don't know what the significance of the different RM-81 designations is. The table below is a detailed listing of allocated Agena serial number blocks, sorted by type designation:

  Serial Range	Designation	Total Number Ordered
  59-2544/2557 60-606/615 60-5454/5463 60-6594/6630 60-6914/6922 62-12585	XRM-81	81
  60-3710/3719	RM-81	10
  63-7368/7406 63-12759/12764 65-10657/10685 66-4390/4432 66-9249/9262 67-14544/14579	SRM-81	167
  61-4530/4536 62-3876/3878 62-4614/4625 62-12202/12213 62-12289/12291 63-13040/13085	SRM-81A	83

  Notes:
  1. The Agena did not receive a new designation in June 1963, when the joint DOD missile designation system was introduced, because spacecraft were not originally part of the new system.
  2. One would expect that SRM-81A designated a newer version than SRM-81 (before 1962, an "A" suffix designated the second version), but the latest blocks are all attributed to plain SRM-81. However, after June 1963 the Agena's designation was no longer covered by any official regulation, so it's possible that the general SRM-81 designator was not meant to designate any specific variant, but was only retained in the serial number list for informal purposes.
  3. The 341 serials do not account for the full number of Agenas built (at least 365).

  Specifications

  Note: Data given by several sources show slight variations. Figures given below may therefore be inaccurate! Because exact numbers for each Agena depend on payload configuration, the data are to be regarded as "typical" values.

  Data for Agena A, Agena B, Agena D:

  	Agena A	Agena B/D
  Length	5.94 m (19.5 ft)	7.56 m (24.8 ft)
  Diameter	1.52 m (5 ft)
  Weight	3850 kg (8500 lb) Fuel: 2945 kg (6500 lb)	7160 kg (15800 lb) Fuel: 6115 kg (13500 lb)
  Propulsion	Bell XLR81-BA-5 liquid-fuel rocket; 68.9 kN (15500 lb) for 120 s	Bell XLR81-BA-9 liquid-fuel rocket; 71.1 kN (16000 lb) for 240 s

  Main Sources

  [1] Jos Heyman: "World Spacecraft Digest 1957-2002", Tiros Space Information, 2003
  [2] Jos Heyman: "Spacecraft Tables 1957-2002", Tiros Space Information, 2003
  [3] RenÚ J. Francillon: "Lockheed Aircraft since 1913", Putnam, 1987
  [4] Norman J. Bowman: "The Handbook of Rockets and Guided Missiles", Perastadion Press, 1963
  [5] Mark Wade: Encyclopedia Astronautica
  [6] Gunter Krebs: Gunter's Space Page
  [7] USAF Aircraft Serial Number Records (data provided by Jos Heyman)

  
  

1959 January 21 - Launch Site: Vandenberg. Launch Complex: 75. Launch Pad: 75-3-4. Launch Vehicle: Thor Agena A. Model: Thor Agena A. LV Configuration: Thor Agena A 160 / Agena A. FAILURE: Launch vehicle failure.

• Thor Agena test Nation: USA. Spacecraft: KH-1. Agency: USAF. COSPAR: F590121A. First flight test of Thor-Agena for KH program. References: 279.

• Discoverer 1 Nation: USA. Payload: KH-1 prototype / Agena A 1022. Mass: 618 kg (1,362 lb). Class: Surveillance. Type: Military. Spacecraft: KH-1. Agency: DARPA. Perigee: 163 km (101 mi). Apogee: 968 km (601 mi). Inclination: 89.70 deg. Period: 96.00 min. COSPAR: 1959-Beta-1. USAF Sat Cat: 13. Decay Date: 1959-03-03. First polar orbiting satellite; KH-1 prototype; did not carry camera or film capsule. References: 1, 2, 5, 6.

• Discoverer 2 Nation: USA. Payload: KH-1 prototype / Agena A 1022. Mass: 743 kg (1,638 lb). Class: Surveillance. Type: Military. Spacecraft: KH-1. Agency: DARPA. Perigee: 239 km (148 mi). Apogee: 346 km (214 mi). Inclination: 89.90 deg. Period: 90.40 min. COSPAR: 1959-Gamma-1. USAF Sat Cat: 14. Decay Date: 1959-04-26. KH-1 prototype; tested capsule recovery techniques; did not carry camera; capsule recovery failed. Because of a timing error, the US believed that the capsule landed somewhere on the island of Spitsbergen, north of Norway, instead of landing in the recovery zone near Hawaii. The capsule was never found; and CIA officials suspect it may have been snatched by the Soviets. The search for this capsule formed the basis of the book and film 'Ice Station Zebra'.

  In the winter of 1960/1961, a US Discovery spy satellite capsule was found by loggers near Kalinin, 200 km north of Moscow. The loggers cracked it open with an axe. Sergei Khrushchev believed this to be the Discoverer 2 capsule. What was left was examined by Soviet engineers but didn’t reveal much information - it was a polished aluminium sphere, 30 cm in diameter, gilded on the exterior. Some said it was found as early as the winter of 1959.References: 1, 2, 5, 6.

• Discoverer 3 Nation: USA. Payload: KH-1 prototype / Agena A 1018. Mass: 753 kg (1,660 lb). Class: Surveillance. Type: Military. Spacecraft: KH-1. Agency: DARPA. COSPAR: F590603A. Decay Date: 1959-06-03. KH-1 prototype; did not carry camera; film capsule recovery failed. References: 5, 126.

• SRV Nation: USA. Spacecraft: KH-1. Agency: USAF. COSPAR: F590603B. References: 279.

• Discoverer 4 Nation: USA. Payload: KH-1 9001. Mass: 743 kg (1,638 lb). Class: Surveillance. Type: Military. Spacecraft: KH-1. Agency: DARPA. COSPAR: F590625A. Decay Date: 1959-06-25. KH-1; 1st generation low resolution photo surveillance. Failed to achieve orbit. References: 5, 126.

• SRV 102 Nation: USA. Spacecraft: KH-1. Agency: USAF. COSPAR: F590625B. References: 279.

• Discoverer 5 Nation: USA. Payload: KH-1 9002 / Agena A 1029. Mass: 781 kg (1,721 lb). Class: Surveillance. Type: Military. Spacecraft: KH-1. Agency: DARPA. Perigee: 214 km (132 mi). Apogee: 731 km (454 mi). Inclination: 79.90 deg. Period: 94.10 min. COSPAR: 1959-Epsilon-1. USAF Sat Cat: 18. Decay Date: 1959-09-28. KH-1; 1st generation low resolution photo surveillance; film capsule boosted into higher orbit, decayed 2/11/61. Mission failed. Power supply failure. No recovery. References: 1, 2, 5, 6.

• Discoverer 5 Capsule Nation: USA. Payload: KH-1 9002 Capsule. Class: Surveillance. Type: Military. Spacecraft: KH-1. Agency: USAF. Perigee: 218 km (135 mi). Apogee: 1,700 km (1,000 mi). Inclination: 78.90 deg. Period: 104.30 min. COSPAR: 1959-Epsilon-2. USAF Sat Cat: 26. Decay Date: 1961-02-11. KH-1; 1st generation low resolution photo surveillance; film capsule boosted into higher orbit, decayed 2/11/61. Mission failed. Power supply failure. No recovery. References: 2, 5, 6.

• Discoverer 6 Nation: USA. Payload: KH-1 9003 / Agena A 1028. Mass: 783 kg (1,726 lb). Class: Surveillance. Type: Military. Spacecraft: KH-1. Agency: DARPA. Perigee: 207 km (128 mi). Apogee: 846 km (525 mi). Inclination: 83.90 deg. Period: 95.10 min. COSPAR: 1959-Zeta-1. USAF Sat Cat: 19. Decay Date: 1959-10-20. KH-1; 1st generation low resolution photo surveillance; film capsule recovery failed. Mission failed. Retro rockets malfunctioned negating recovery. References: 1, 2, 5, 6.

• Discoverer 7 Nation: USA. Payload: KH-1 9004 / Agena A 1051. Mass: 794 kg (1,750 lb). Class: Surveillance. Type: Military. Spacecraft: KH-1. Agency: DARPA. Perigee: 158 km (98 mi). Apogee: 820 km (500 mi). Inclination: 81.60 deg. Period: 94.40 min. COSPAR: 1959-Kappa-1. USAF Sat Cat: 24. Decay Date: 1959-11-26. KH-1; 1st generation low resolution photo surveillance; satellite tumbled; film capsule not recovered. Mission failed. Failed to achieve orbit. References: 1, 2, 5, 6.

• Discoverer 8 Nation: USA. Payload: KH-1 9005 / Agena A 1050. Mass: 795 kg (1,752 lb). Class: Surveillance. Type: Military. Spacecraft: KH-1. Agency: U.S. Air Force. Perigee: 186 km (115 mi). Apogee: 1,661 km (1,032 mi). Inclination: 80.50 deg. Period: 103.50 min. COSPAR: 1959-Lambda-1. USAF Sat Cat: 25. Decay Date: 1960-03-08. KH-1; 1st generation low resolution photo surveillance; film capsule recovery failed. Mission failed. Eccentric orbit negating recovery. References: 1, 2, 5, 6.

• Discoverer 9 Nation: USA. Payload: KH-1 9006. Mass: 765 kg (1,686 lb). Class: Surveillance. Type: Military. Spacecraft: KH-1. Agency: U.S. Air Force. COSPAR: F600204A. Decay Date: 1960-02-04. KH-1; 1st generation low resolution photo surveillance. Mission failed. References: 5, 126.

• SRV 113 Nation: USA. Spacecraft: KH-1. Agency: USAF. COSPAR: F600204B. References: 279.

• Discoverer 10 Nation: USA. Payload: KH-1 9007. Mass: 765 kg (1,686 lb). Class: Surveillance. Type: Military. Spacecraft: KH-1. Agency: U.S. Air Force. COSPAR: F600219A. Decay Date: 1960-02-19. KH-1; Mission failed. References: 5, 126.

• SRV 110 Nation: USA. Spacecraft: KH-1. Agency: USAF. COSPAR: F600219B. References: 279.

• Discoverer 11 Nation: USA. Payload: KH-1 9008 / Agena A 1055. Mass: 790 kg (1,740 lb). Class: Surveillance. Type: Military. Spacecraft: KH-1. Agency: U.S. Air Force. Perigee: 166 km (103 mi). Apogee: 603 km (374 mi). Inclination: 80.40 deg. Period: 92.20 min. COSPAR: 1960-Delta-1. USAF Sat Cat: 32. Decay Date: 1960-04-26. KH-1; film capsule recovery failed. Mission failed. Attitude control system malfunctioned. References: 1, 2, 5, 6.

• Discoverer 12 Nation: USA. Payload: KH-1 prototype. Mass: 790 kg (1,740 lb). Class: Surveillance. Type: Military. Spacecraft: KH-1. Agency: U.S. Air Force. COSPAR: F600629A. Decay Date: 1960-06-29. KH-1 prototype; designed to test capsule recovery system; did not carry camera. References: 5, 126.

• SRV Nation: USA. Spacecraft: KH-1. Agency: USAF. COSPAR: F600629B. References: 279.

• Discoverer 13 Nation: USA. Payload: KH-1 prototype / Agena A 1057. Mass: 850 kg (1,870 lb). Class: Surveillance. Type: Military. Spacecraft: KH-1. Agency: U.S. Air Force. Perigee: 258 km (160 mi). Apogee: 683 km (424 mi). Inclination: 82.80 deg. Period: 94.00 min. COSPAR: 1960-Theta-1. USAF Sat Cat: 48. Decay Date: 1960-11-14. KH-1 prototype; designed to test capsule recovery system; did not carry camera; capsule successfully recovered from ocean. References: 1, 2, 5, 6.

• Discoverer 14 Nation: USA. Payload: KH-1 9009 / Agena A 1056. Mass: 850 kg (1,870 lb). Class: Surveillance. Type: Military. Spacecraft: KH-1. Agency: U.S. Air Force. Perigee: 177 km (109 mi). Apogee: 803 km (498 mi). Inclination: 79.60 deg. Period: 94.40 min. COSPAR: 1960-Kappa-1. USAF Sat Cat: 54. Decay Date: 1960-09-16. KH-1; film capsule recovered 1.2 days later; 1st successful photosurveillance mission. First successful mission. Cameras operated satisfactorily. References: 1, 2, 5, 6.

• Discoverer 15 Nation: USA. Payload: KH-1 9010 / Agena A 1058. Mass: 863 kg (1,902 lb). Class: Surveillance. Type: Military. Spacecraft: KH-1. Agency: U.S. Air Force. Perigee: 200 km (120 mi). Apogee: 755 km (469 mi). Inclination: 80.90 deg. Period: 94.10 min. COSPAR: 1960-Mu-1. USAF Sat Cat: 57. Decay Date: 1960-10-18. KH-1; film capsule lost at sea. Mission failed. Attained orbit successfully. Capsule sank prior to retrieval. References: 1, 2, 5, 6.

• McDowell, Jonathan, Jonathan's Space Home Page, Harvard University, 1997-present. Jonathan McDowell's complete on-line listing of all objects orbited and over 20,000 rocket launches Accessed at: http://www.planet4589.org/jsr.html.

• Koelle, Heinz Hermann,, Handbook of Astronautical Engineering, McGraw-Hill,New York, 1961. The only such comprehensive handbook ever produced, and at the dawn of the space age.