Thor Ablestar Credit - © Thom Media Gallery

As Thor Able but with enlarged second Ablestar second stage with 2 1/2 x greater burn time.

As is almost always the case in such programs, the Air Force requested increases in the propulsion system capabilities in an effort to meet their ever-expanding mission requirements. As a result, the stainless steel version of the basic Able engine was selected, and it was uprated to increase thrust 34.7 kN to 37.0 kN and to increase the duration 2-1/2 times (easily done with the stainless steel thrust chamber) - and this configuration was called Ablestar. The Ablestar also included modifications that allowed in-space restarting - a first in the industry. The time required for developing and qualifying the Ablestar propulsion system was eight months, most of which was needed for the design, development and qualification of the much larger propellant tanks and titanium helium spheres. These remarkably short development times was a result of the basic simplicity of the Able design - mainly the low chamber pressure, hypergolic propellants, and gas pressurized propellant tanks. This simplicity also resulted in a number of additional very desirable features:

• The ability to achieve rapid, relatively low cost modifications, and high reliability for a variety of missions
• The ability to shift back to the aluminum thrust chamber and injector which provided an extremely good thrust to weight ratio (180, based on 3500 kgf thrust and a weight of 19.5 kg)
• Very light weight tankage based on heat treated 410 stainless steel
• Easily adjustable run time (in the stainless steel version) based on simply varying the length of the cylindrical section of the tanks.

Manufacturer: Douglas. Launches: 19. Failures: 5. Success Rate: 73.68%. First Launch Date: 1960-04-13. Last Launch Date: 1965-08-13. Launch data is: complete. LEO Payload: 150 kg (330 lb). to: 1,100 km Orbit. at: 90.00 degrees. Associated Spacecraft: Anna, APL, Calsphere, Courier, DODECAPOLE, GRAB, Injun, Lofti, Lofti 2, SECOR, Surcal, Tempsat, TRAAC, Transit. Liftoff Thrust: 667.200 kN (149,993 lbf). Total Mass: 53,000 kg (116,000 lb). Core Diameter: 2.44 m (8.00 ft). Total Length: 29.00 m (95.00 ft). Flyaway Unit Cost $: 12.830 million. in: 1985 unit dollars.

2 stage vehicle consisting of 1 x Thor DM-21 + 1 x Able-Star/AJ10-104

Apogee: 1,500 km (900 mi). Liftoff Thrust: 668.000 kN (150,172 lbf). Total Mass: 53,000 kg (116,000 lb). Core Diameter: 2.44 m (8.00 ft). Total Length: 23.50 m (77.00 ft).

2 stage vehicle consisting of 1 x Thor DSV-2A + 1 x Able-Star/AJ10-104D

Apogee: 1,500 km (900 mi). Liftoff Thrust: 756.000 kN (169,955 lbf). Total Mass: 53,000 kg (116,000 lb). Core Diameter: 2.44 m (8.00 ft). Total Length: 23.80 m (78.00 ft).

• Stage Number: 1. 1 x Stage: Thor DM-21. Gross Mass: 48,354 kg (106,602 lb). Empty Mass: 2,948 kg (6,499 lb). Thrust (vac): 760.643 kN (170,999 lbf). Isp: 285 sec. Burn time: 164 sec. Isp(sl): 250 sec. Diameter: 2.44 m (8.00 ft). Span: 2.44 m (8.00 ft). Length: 18.41 m (60.40 ft). Propellants: Lox/Kerosene. No Engines: 1. Engine: MB-3-1.

• Stage Number: 2. 1 x Stage: Able-Star. Gross Mass: 4,470 kg (9,850 lb). Empty Mass: 590 kg (1,300 lb). Thrust (vac): 35.088 kN (7,888 lbf). Isp: 278 sec. Burn time: 296 sec. Isp(sl): 210 sec. Diameter: 1.40 m (4.50 ft). Span: 1.40 m (4.50 ft). Length: 5.88 m (19.29 ft). Propellants: Nitric acid/UDMH. No Engines: 1. Engine: AJ10-104. As is almost always the case in such programs, the Air Force requested increases in the propulsion system capabilities in an effort to meet their ever-expanding mission requirements. As a result, the stainless steel version of the basic Able engine was selected, and it was uprated to increase thrust 34.7 kN to 37.0 kN and to increase the duration 2-1/2 times (easily done with the stainless steel thrust chamber) - and this configuration was called Ablestar. The Ablestar also included modifications that allowed in-space restarting - a first in the industry. The time required for developing and qualifying the Ablestar propulsion system was eight months, most of which was needed for the design, development and qualification of the much larger propellant tanks and titanium helium spheres. These remarkably short development times was a result of the basic simplicity of the Able design - mainly the low chamber pressure, hypergolic propellants, and gas pressurized propellant tanks. This simplicity also resulted in a number of additional very desirable features:
  • The ability to achieve rapid, relatively low cost modifications, and high reliability for a variety of missions
  • The ability to shift back to the aluminum thrust chamber and injector which provided an extremely good thrust to weight ratio (180, based on 3500 kgf thrust and a weight of 19.5 kg)
  • Very light weight tankage based on heat treated 410 stainless steel
  • Easily adjustable run time (in the stainless steel version) based on simply varying the length of the cylindrical section of the tanks.
  In addition, the basic philosophy of pressure fed, low chamber pressure and ablative (rather than regeneratively cooled) thrust chambers for upper stage engines produced outstanding reliability and scalability. In a vacuum engine, a low chamber pressure still provides a reasonable expansion ratio, and thus reasonable performance. Secondly, low chamber pressure allows use of a very simple, pressure fed propellant system with relatively light and inexpensive tanks. Thirdly, the low chamber pressure results in lower heat transfer rates, thus making ablative chambers more practical - and they are inherently less expensive, and much mere reliable. And finally ablative chambers greatly simplify restarts in a vacuum environment because there are essentially no problems with cooling jacket and manifold fill times or coking in the coolant system.

1960 April 13 - 12:02 GMT - Launch Site: Cape Canaveral. Launch Complex: LC17. Launch Pad: LC17B. Launch Vehicle: Thor Able-Star. Model: Thor Ablestar. LV Configuration: Thor Ablestar 257 AB002?.

• Transit 1B Nation: USA. Program: Transit. Mass: 121 kg (266 lb). Class: Navigation. Spacecraft: Transit. Agency: DARPA. Perigee: 363 km (225 mi). Apogee: 644 km (400 mi). Inclination: 51.20 deg. Period: 94.60 min. COSPAR: 1960-Gamma-2. USAF Sat Cat: 31. Duration: 89.00 days. Decay Date: 1967-10-05. The Able-Star second stage demonstrated the first engine restart in space and the feasibility of using satellites as navigational aids. The first experimental Transit satellite to achieve orbit operated for 89 days. It transmitted on two frequency pairs to test the technique for refraction correction and to determine if the transmitted frequencies should be close together or far apart. It also tested a magnetic torque device for spacecraft attitude control - the first satellite to do so.References: 1, 2, 5, 6.

• Dummy subsatellite Nation: USA. Payload: GRAB dummy. Mass: 18 kg (39 lb). Class: Sigint. Spacecraft: GRAB. Agency: USAF. COSPAR: 1960-Gamma-3. USAF Sat Cat: 33. Decay Date: 1960-07-17. References: 279.

• Transit 2A Nation: USA. Program: Transit. Mass: 101 kg (222 lb). Class: Navigation. Spacecraft: Transit. Agency: U.S. Navy. Perigee: 604 km (375 mi). Apogee: 988 km (613 mi). Inclination: 66.70 deg. Period: 100.80 min. COSPAR: 1960-Eta-1. USAF Sat Cat: 45. Also returned geodetic data. Similar to Transit 1B, it transmitted until 26 October 1962. A planned Transit 2B was considered redundant and never built. References: 1, 2, 5, 6.

• Solrad 1 Nation: USA. Payload: GRAB 1. Mass: 19 kg (41 lb). Class: Sigint. Spacecraft: GRAB. Agency: U.S. Navy. Perigee: 596 km (370 mi). Apogee: 935 km (580 mi). Inclination: 66.70 deg. Period: 100.20 min. COSPAR: 1960-Eta-2. USAF Sat Cat: 46. Solar radiation data. Spacecraft engaged in research and exploration of the upper atmosphere or outer space (US Cat B). References: 1, 2, 5, 6.

• Courier 1A Nation: USA. Mass: 225 kg (496 lb). Class: Communications. Spacecraft: Courier. Agency: DARPA. COSPAR: F600818A. Decay Date: 1960-08-18. Experimental communications sattelite. References: 5, 126.

• Courier 1B Nation: USA. Mass: 230 kg (500 lb). Class: Technology. Type: Comsat. Spacecraft: Courier. Agency: U.S. Army. Perigee: 967 km (600 mi). Apogee: 1,214 km (754 mi). Inclination: 28.30 deg. Period: 107.10 min. COSPAR: 1960-Nu-1. USAF Sat Cat: 58. Experimental communications. Spacecraft engaged in practical applications and uses of space technology such as weather or communication (US Cat C). References: 1, 2, 5, 6.

• Transit 3A Nation: USA. Program: Transit. Payload: Transit 3A. Mass: 91 kg (200 lb). Class: Navigation. Spacecraft: Transit. Agency: U.S. Navy. COSPAR: F601130A. Decay Date: 1960-11-30. Destroyed by range safety; launched with Solrad 2. Thor shut down too early. References: 5, 126.

• Solrad 2 Nation: USA. Payload: GRAB 2. Mass: 18 kg (39 lb). Class: Sigint. Spacecraft: GRAB. Agency: USAF. COSPAR: F601130B. References: 279.

• Transit 3B Nation: USA. Program: Transit. Mass: 112 kg (246 lb). Class: Navigation. Spacecraft: Transit. Agency: U.S. Navy. COSPAR: 1961-Eta-1. USAF Sat Cat: 87. Decay Date: 1961-02-22. Lofti 1 piggyback payload did not separate. Nevertheless Transit 3B returned useful data needed for design of the operational satellites. It carried a digital clock driven by the same oscillator that drove the transmitters. It transmitted timing signals governed by the clock and a 384-bit memory. This allowed testing of the techniques for loading the memory from the ground, the ability of the memory to hold a message in orbit, and the ability to encode the memory contents by means of a frequency modulation on one of the main transmitters. It was also shown that ±60° phase modulation could be used to transmit the contents of the satellite memory without degradation of the accuracy of the Doppler signal and Doppler measurements.References: 5, 6.

• Lofti 1 Nation: USA. Program: Transit. Mass: 25 kg (55 lb). Class: Navigation. Spacecraft: Transit. Agency: U.S. Navy. Perigee: 188 km (116 mi). Apogee: 983 km (610 mi). Inclination: 28.30 deg. Period: 96.40 min. COSPAR: 1961-Eta-2. USAF Sat Cat: 87. Decay Date: 1961-03-30. Failed to separate from Transit 3B. References: 1, 2, 5, 6.

• Lofti Nation: USA. Spacecraft: Lofti. Agency: USAF. COSPAR: 1961-Eta-xx. References: 279.

• Transit 4A Nation: USA. Program: Transit. Mass: 79 kg (174 lb). Class: Navigation. Spacecraft: Transit. Agency: U.S. Navy. Perigee: 865 km (537 mi). Apogee: 986 km (612 mi). Inclination: 66.80 deg. Period: 103.50 min. COSPAR: 1961-Omicron-1. USAF Sat Cat: 116. Transits 4A and 4B were drum-shaped instead of spherical to provide more space for solar cells. In addition, operational 150-and 400-MHz frequencies were used for the first time. Carried SNAP-3A nuclear power source. References: 1, 2, 5, 6.

• Injun 1 Nation: USA. Mass: 25 kg (55 lb). Class: Earth. Type: Magnetosphere. Spacecraft: Injun. Agency: U.S. Navy. Perigee: 869 km (539 mi). Apogee: 992 km (616 mi). Inclination: 66.80 deg. Period: 103.60 min. COSPAR: 1961-Omicron-2. USAF Sat Cat: 117. Dual launch; failed to separate from Solrad 3; still returned radiation data. Space craft engaged in investigation of spaceflight techniques and technology (US Cat A). References: 1, 2, 5, 6.

• Solrad 3 Nation: USA. Payload: GRAB 3. Mass: 18 kg (39 lb). Class: Sigint. Spacecraft: GRAB. Agency: USAF. COSPAR: 1961-Omicron-xx. References: 279.

• Transit 4B Nation: USA. Program: Transit. Mass: 86 kg (189 lb). Class: Navigation. Spacecraft: Transit. Agency: U.S. Navy. Perigee: 953 km (592 mi). Apogee: 1,104 km (685 mi). Inclination: 32.40 deg. Period: 105.70 min. COSPAR: 1961-A-Eta-1. USAF Sat Cat: 202. Together, Transits 4A and 4B allowed the determination of harmonics in the Earth’s gravity field that had not yet been evaluated, and they also allowed firm navigational ties to be established from continent to continent as well as to isolated islands. As a result, it was discovered that the position of Hawaii was incorrect by 1 km. Carried SNAP 3 nuclear power source.References: 1, 2, 5, 6.

• TRAAC Nation: USA. Mass: 109 kg (240 lb). Class: Technology. Spacecraft: TRAAC. Agency: U.S. Navy. Perigee: 956 km (594 mi). Apogee: 1,107 km (687 mi). Inclination: 32.40 deg. Period: 105.80 min. COSPAR: 1961-A-Eta-2. USAF Sat Cat: 205. Transit Research and Attitude Control. Spacecraft engaged in research and exploration of the upper atmosphere or outer space (US Cat B). References: 1, 2, 5, 6.

• Lofti 2 Nation: USA. Mass: 99 kg (218 lb). Class: Earth. Type: Magnetosphere. Spacecraft: Lofti 2. Agency: U.S. Navy. COSPAR: F620124A. Decay Date: 1962-01-24. Carried 5 satellites. References: 5, 126.

• Solrad 4 Nation: USA. Payload: GRAB 4. Mass: 18 kg (39 lb). Class: Sigint. Spacecraft: GRAB. Agency: USAF. COSPAR: F620124B. References: 279.

• Secor Nation: USA. Payload: Secor. Spacecraft: SECOR. Agency: USAF. COSPAR: F620124C. References: 279.

• Injun 2 Nation: USA. Payload: Injun 2. Spacecraft: Injun. Agency: USAF. COSPAR: F620124D. References: 279.

• Surcal Nation: USA. Payload: Surcal. Class: Calibration. Spacecraft: Surcal. Agency: USAF. COSPAR: F620124E. References: 279.

• Anna 1A Nation: USA. Payload: Anna 1A. Mass: 160 kg (350 lb). Class: Earth. Type: Geodetic. Spacecraft: Anna. Agency: U.S. Army, U.S. Navy, U.S. Air Force, NASA. COSPAR: F620510A. Decay Date: 1962-05-10. USN, USAF, US Army, NASA joint program. References: 5, 126.

• Anna 1B Nation: USA. Mass: 161 kg (354 lb). Class: Earth. Type: Geodetic. Spacecraft: Anna. Agency: U.S. Navy. Perigee: 1,075 km (667 mi). Apogee: 1,181 km (733 mi). Inclination: 50.10 deg. Period: 107.90 min. COSPAR: 1962-B-Mu-1. USAF Sat Cat: 446. Spacecraft engaged in research and exploration of the upper atmosphere or outer space (US Cat B). References: 1, 2, 5, 6.

• Transit 5BN-1 Nation: USA. Program: Transit. Mass: 70 kg (154 lb). Class: Navigation. Spacecraft: Transit. Agency: USN. Perigee: 1,066 km (662 mi). Apogee: 1,125 km (699 mi). Inclination: 90.10 deg. Period: 107.20 min. COSPAR: 1963-038B. USAF Sat Cat: 670. First test of nuclear-powered Transit operational prototype. Carried SNAP-9A nuclear power source. The satellite achieved gravity-gradient stabilization, but upside down, making the signal level too low for operational users with low-gain antennas. However, geodetic and navigational evaluation data were obtained.References: 1, 2, 5, 6.

• Transit 5E-1 Nation: USA. Program: Transit. Payload: APL SN 39. Mass: 61 kg (134 lb). Class: Earth. Type: Magnetosphere. Spacecraft: Transit. Agency: USN. Perigee: 1,065 km (661 mi). Apogee: 1,123 km (697 mi). Inclination: 90.10 deg. Period: 107.10 min. COSPAR: 1963-038C. USAF Sat Cat: 671. The missions of Satellite 1963-038C were to measure omnidirectional flux of protons and electrons at various energy levels, radiation effects on transistors, and the effectiveness of thermal coatings. The satellite was launched together with a classified Department of Defense spacecraft on September 28, 1963. Its planned orbit was apogee 1120 kilometres, perigee 1070 kilometres, inclination 88.9 degrees. The satellite weighed 62 kg; its body was in the shape of an 0.46 m x 0.25 m octagonal prism. It was powered by four solar blades and transmited on 136, 162, and 324 mcs. The spacecraft was built for the Bureau of Naval Weapons. In 1967 it was still sending usable data from all systems.References: 1, 2, 5, 6.

• Transit 5BN-2 Nation: USA. Program: Transit. Mass: 75 kg (165 lb). Class: Navigation. Spacecraft: Transit. Agency: USN. Perigee: 1,061 km (659 mi). Apogee: 1,110 km (680 mi). Inclination: 90.10 deg. Period: 107.00 min. COSPAR: 1963-049B. USAF Sat Cat: 704. Transit operational prototype powered by a SNAP-9A nuclear power source. First operational navigation satellite. It was used regularly by both surface and submarine units of the Navy until November 1964. From this point in time the US Navy had continuous use of satellite navigation.References: 1, 2, 5, 6.

• Transit 5E-3 Nation: USA. Program: Transit. Mass: 53 kg (116 lb). Class: Earth. Type: Magnetosphere. Spacecraft: Transit. Agency: USN. Perigee: 1,060 km (650 mi). Apogee: 1,108 km (688 mi). Inclination: 90.10 deg. Period: 106.90 min. COSPAR: 1963-049C. USAF Sat Cat: 705. Radiation monitoring. References: 1, 2, 5, 6.

• Transit 5BN-3 Nation: USA. Program: Transit. Mass: 75 kg (165 lb). Class: Navigation. Spacecraft: Transit. Agency: U.S. Navy. COSPAR: F640421A. Decay Date: 1964-04-21. Carried SNAP-9A nuclear power source. After this launch failure it was decided that operational Transits would be solar-powered only. References: 5, 126.

• Transit 5E-4 Nation: USA. Program: Transit. Class: Earth. Type: Magnetosphere. Spacecraft: Transit. Agency: U.S. Navy. COSPAR: F640421B. Radiation monitoring. References: 279.

• Transit O-1 Nation: USA. Program: Transit. Payload: NNS 30010 / Ablestar 016. Mass: 60 kg (132 lb). Class: Navigation. Spacecraft: Transit. Agency: USN. Perigee: 1,046 km (649 mi). Apogee: 1,077 km (669 mi). Inclination: 90.20 deg. Period: 106.40 min. COSPAR: 1964-063B. USAF Sat Cat: 897. Naval Avionics Facility-assembled production spacecraft. Failed after a few days operation. References: 1, 2, 5, 6.

• Calsphere 1 Nation: USA. Payload: Dragsphere 1. Mass: 1.00 kg (2.20 lb). Class: Calibration. Spacecraft: Calsphere. Agency: USN. Perigee: 997 km (619 mi). Apogee: 1,034 km (642 mi). Inclination: 90.10 deg. Period: 105.50 min. COSPAR: 1964-063C. USAF Sat Cat: 900. Space craft engaged in investigation of spaceflight techniques and technology (US Cat A). References: 1, 2, 5, 6.

• Calsphere 2 Nation: USA. Payload: Dragsphere 2. Mass: 10 kg (22 lb). Class: Calibration. Spacecraft: Calsphere. Agency: USN. Perigee: 1,049 km (651 mi). Apogee: 1,078 km (669 mi). Inclination: 90.20 deg. Period: 106.50 min. COSPAR: 1964-063E. USAF Sat Cat: 902. Space craft engaged in investigation of spaceflight techniques and technology (US Cat A). References: 1, 2, 5, 6.

• Transit 5E-5 Nation: USA. Program: Transit. Payload: APL SN 43. Mass: 78 kg (171 lb). Class: Earth. Type: Magnetosphere. Spacecraft: Transit. Agency: USN. Perigee: 1,007 km (625 mi). Apogee: 1,064 km (661 mi). Inclination: 89.80 deg. Period: 105.90 min. COSPAR: 1964-083C. USAF Sat Cat: 959. Celestial UV, magnetic field data. References: 1, 2, 5, 6.

• Transit O-2 Nation: USA. Program: Transit. Payload: NNS 30020. Mass: 60 kg (132 lb). Class: Navigation. Spacecraft: Transit. Agency: USN. Perigee: 1,020 km (630 mi). Apogee: 1,079 km (670 mi). Inclination: 89.80 deg. Period: 106.20 min. COSPAR: 1964-083D. USAF Sat Cat: 965. Naval Avionics Facility-assembled production spacecraft. Failed after a few days operation. References: 1, 2, 5, 6.

• Transit-O-3 Nation: USA. Program: Transit. Mass: 60 kg (132 lb). Class: Navigation. Spacecraft: Transit. Agency: USN. Perigee: 191 km (118 mi). Apogee: 418 km (259 mi). Inclination: 90.00 deg. Period: 90.70 min. COSPAR: 1965-017A. USAF Sat Cat: 1303. Decay Date: 1965-06-14. Naval Avionics Facility-assembled production spacecraft. Failed after a few weeks operation. References: 1, 2, 5, 6.

• SECOR 2 Nation: USA. Payload: EGRS 2. Mass: 18 kg (39 lb). Class: Earth. Type: Geodetic. Spacecraft: SECOR. Agency: USA ACE. Perigee: 296 km (183 mi). Apogee: 1,014 km (630 mi). Inclination: 90.00 deg. Period: 97.90 min. COSPAR: 1965-017B. USAF Sat Cat: 1250. Decay Date: 1968-02-26. Failed. Space craft engaged in investigation of spaceflight techniques and technology (US Cat A). References: 1, 2, 5, 6.

• Transit O-4 Nation: USA. Program: Transit. Payload: NNS 30040. Mass: 61 kg (134 lb). Class: Navigation. Spacecraft: Transit. Agency: USN. Perigee: 1,016 km (631 mi). Apogee: 1,125 km (699 mi). Inclination: 90.10 deg. Period: 106.60 min. COSPAR: 1965-048A. USAF Sat Cat: 1420. Spacecraft built by Naval Avionics Facility, but refurbished by APL. Operated for 7 to 11 months, but then failed due to poor workmanship of NAFI components. References: 1, 2, 5, 6.

• Dodecapole 2 Nation: USA. Payload: PORCUPINE 2. Mass: 4.00 kg (8.80 lb). Class: Calibration. Spacecraft: DODECAPOLE. Agency: USN. Perigee: 979 km (608 mi). Apogee: 1,051 km (653 mi). Inclination: 90.00 deg. Period: 105.40 min. COSPAR: 1965-065C. USAF Sat Cat: 1510. Surveillance Calibration; dodecahedron; extended 12 25 ft. antennas. Space craft engaged in investigation of spaceflight techniques and technology (US Cat A). References: 1, 2, 5, 6.

• Tempsat 1 Nation: USA. Mass: 9.00 kg (19.80 lb). Class: Calibration. Spacecraft: Tempsat. Agency: USN. Perigee: 1,082 km (672 mi). Apogee: 1,188 km (738 mi). Inclination: 89.90 deg. Period: 108.00 min. COSPAR: 1965-065E. USAF Sat Cat: 1512. Surveillance Calibration; black 14 inch dia. sphere. Space craft engaged in investigation of spaceflight techniques and technology (US Cat A). References: 1, 2, 5, 6.

• Transit O-5 Nation: USA. Program: Transit. Payload: NNS 30050. Mass: 61 kg (134 lb). Class: Navigation. Spacecraft: Transit. Agency: USN. Perigee: 1,078 km (669 mi). Apogee: 1,183 km (735 mi). Inclination: 89.90 deg. Period: 107.90 min. COSPAR: 1965-065F. USAF Sat Cat: 1514. Naval Avionics Facility-assembled production spacecraft. Failed after a few weeks operation. References: 1, 2, 5, 6.

• Long Rod Nation: USA. Payload: Navspasur Rod. Class: Calibration. Spacecraft: Surcal. Agency: USN. Perigee: 1,090 km (670 mi). Apogee: 1,194 km (741 mi). Inclination: 90.00 deg. Period: 108.10 min. COSPAR: 1965-065G. USAF Sat Cat: 1515. Space craft engaged in investigation of spaceflight techniques and technology (US Cat A). References: 1, 2, 5, 6.

• Calsphere 4A Nation: USA. Payload: NRL PL 158?. Mass: 2.00 kg (4.40 lb). Class: Calibration. Spacecraft: Calsphere. Agency: USN. Perigee: 1,077 km (669 mi). Apogee: 1,179 km (732 mi). Inclination: 90.10 deg. Period: 107.90 min. COSPAR: 1965-065H. USAF Sat Cat: 1520. Surveillance Calibration; white 14 inch dia. sphere. References: 2, 5, 6.

• SURCAL 5 Nation: USA. Payload: NRL PL150C?. Class: Calibration. Spacecraft: SURCAL. Agency: USN. Perigee: 1,083 km (672 mi). Apogee: 1,196 km (743 mi). Inclination: 90.00 deg. Period: 108.11 min. COSPAR: 1965-065K. USAF Sat Cat: 1521. References: 279.

• 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.