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Thor Ablestar

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Thor Ablestar Credit: © Thomas Kladiva - Thomas Kladiva

AKA: Thor Able-Star. Status: Retired 1965. First Launch: 1960-04-13. Last Launch: 1965-08-13. Number: 19 . Payload: 150 kg (330 lb). Thrust: 667.20 kN (149,993 lbf). Gross mass: 53,000 kg (116,000 lb). Height: 29.00 m (95.00 ft). Diameter: 2.44 m (8.00 ft). Apogee: 1,100 km (600 mi).

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.

LEO Payload: 150 kg (330 lb) to a 1,100 km orbit at 90.00 degrees. Flyaway Unit Cost 1985$: 12.830 million.

Stage Data - Thor Able-Star

• Stage 1. 1 x 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. Status: Out of Production.

• Stage 2. 1 x 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. Status: Out of Production. Comments: Ultimate development of lineage Aerobee - Vanguard second stage - Able upper stage. Replaced by Agena.

Photo Gallery

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Thor Able Star Credit: © Mark Wade

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Launch Complex 17B Launch Complex 17B - Cape Canaveral

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• Ablestar second stage completed - .

  Aerojet-General Corporation completed development of the Ablestar second stage for use with Atlas, Titan, or Thor boosters. Primary improvements over the previous Able vehicles were increased propellant capacity, multiple restart capability, and full-time attitude control.

• Transit 1B - . Mass: 121 kg (266 lb). Nation: USA. Agency: DARPA. Program: Transit. Class: Navigation. Type: Navigation satellite. Spacecraft: Transit. Duration: 89.00 days. Decay Date: 1967-10-05 . USAF Sat Cat: 31 . COSPAR: 1960-Gamma-2. Apogee: 644 km (400 mi). Perigee: 363 km (225 mi). Inclination: 51.20 deg. Period: 94.60 min.

  The first Thor/Ablestar launched from Cape Canaveral placed the Navy's Transit IB navigation satellite into orbit. This was the first navigation satellite to be placed in orbit. The Ablestar upper stage demonstrated the first engine restart in space. 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.

• Dummy subsatellite - . Payload: GRAB dummy. Mass: 18 kg (39 lb). Nation: USA. Agency: USAF. Class: Surveillance. Type: SIGINT. Spacecraft: GRAB. Decay Date: 1960-07-17 . USAF Sat Cat: 33 . COSPAR: 1960-Gamma-3. Apogee: 615 km (382 mi). Perigee: 285 km (177 mi). Inclination: 51.30 deg. Period: 93.60 min. Mass model of GRAB ELINT satellite..

• Transit 2A - . Mass: 101 kg (222 lb). Nation: USA. Agency: USN. Program: Transit. Class: Navigation. Type: Navigation satellite. Spacecraft: Transit. USAF Sat Cat: 45 . COSPAR: 1960-Eta-1. Apogee: 988 km (613 mi). Perigee: 604 km (375 mi). Inclination: 66.70 deg. Period: 100.80 min.

  A Thor/Ablestar booster placed a U.S. Navy Transit IIA research and development navigation satellite into orbit using the Ablestar second stage with a restart engine. A smaller parasitic radiation-measuring satellite, the Galactic Radiation Experiment Background (GREB), was also placed into orbit. This was the first time two satellites had been carried in "piggyback" alignment on a single booster. Also returned geodetic data. Similar to Transit 1B, it transmitted until 26 October 1962. A planned Transit 2B was considered redundant and never built.

• Solrad 1 - . Payload: Grab 1. Mass: 19 kg (41 lb). Nation: USA. Agency: USN. Class: Surveillance. Type: SIGINT. Spacecraft: GRAB. USAF Sat Cat: 46 . COSPAR: 1960-Eta-2. Apogee: 935 km (580 mi). Perigee: 596 km (370 mi). Inclination: 66.70 deg. Period: 100.20 min.

  ELINT satellite, retransmitting to US ground stations signals from Soviet radar stations. Classified at time; official purpose and secondary payload collected solar radiation data. Officially: Spacecraft engaged in research and exploration of the upper atmosphere or outer space (US Cat B).

• Courier 1A - . Mass: 225 kg (496 lb). Nation: USA. Agency: DARPA. Class: Communications. Type: Military communications satellite. Spacecraft: Courier. Decay Date: 1960-08-18 . Discoverer XIV was launched from Vandenberg AFB aboard a Thor/Agena A booster.' Experimental communications sattelite..

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

• Transit 3A - . Mass: 91 kg (200 lb). Nation: USA. Agency: USN. Program: Transit. Class: Navigation. Type: Navigation satellite. Spacecraft: Transit. Decay Date: 1960-11-30 . Destroyed by range safety; launched with Solrad 2. Thor shut down too early..

• Solrad 2 - . Payload: Grab B. Mass: 18 kg (39 lb). Nation: USA. Agency: USAF. Class: Surveillance. Type: SIGINT. Spacecraft: GRAB. ELINT satellite..

• Transit 3B - . Mass: 112 kg (246 lb). Nation: USA. Agency: USN. Program: Transit. Class: Navigation. Type: Navigation satellite. Spacecraft: Transit. Decay Date: 1961-02-22 . USAF Sat Cat: 87 . COSPAR: 1961-Eta-1. Apogee: 225 km (139 mi). Perigee: 135 km (83 mi). Inclination: 28.40 deg. Period: 88.10 min.

  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.

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

• Lofti - . Mass: 26 kg (57 lb). Nation: USA. Agency: USAF. Spacecraft: Lofti. COSPAR: 1961-Eta-xx.

• Transit 4A - . Mass: 79 kg (174 lb). Nation: USA. Agency: USN. Program: Transit. Class: Navigation. Type: Navigation satellite. Spacecraft: Transit. USAF Sat Cat: 116 . COSPAR: 1961-Omicron-1. Apogee: 986 km (612 mi). Perigee: 865 km (537 mi). Inclination: 66.80 deg. Period: 103.50 min. 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..

• Injun 1 - . Mass: 25 kg (55 lb). Nation: USA. Agency: USN. Class: Earth. Type: Magnetosphere satellite. Spacecraft: Injun. USAF Sat Cat: 117 . COSPAR: 1961-Omicron-2. Apogee: 992 km (616 mi). Perigee: 869 km (539 mi). Inclination: 66.80 deg. Period: 103.60 min. 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). .

• Solrad 3 - . Payload: Grab 2. Mass: 18 kg (39 lb). Nation: USA. Agency: USAF. Class: Surveillance. Type: SIGINT. Spacecraft: GRAB. COSPAR: 1961-Omicron-xx. ELINT satellite, retransmitting to US ground stations signals from Soviet radar stations. Classified at time; official purpose and secondary payload collected solar radiation data..

• Transit 4B - . Mass: 86 kg (189 lb). Nation: USA. Agency: USN. Program: Transit. Class: Navigation. Type: Navigation satellite. Spacecraft: Transit. USAF Sat Cat: 202 . COSPAR: 1961-A-Eta-1. Apogee: 1,104 km (685 mi). Perigee: 953 km (592 mi). Inclination: 32.40 deg. Period: 105.70 min.

  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.

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

• Lofti 2 - . Mass: 99 kg (218 lb). Nation: USA. Agency: USN. Class: Earth. Type: Magnetosphere satellite. Spacecraft: Lofti 2. Decay Date: 1962-01-24 . Carried 5 satellites..

• Solrad 4 - . Payload: Grab D. Mass: 18 kg (39 lb). Nation: USA. Agency: USAF. Class: Surveillance. Type: SIGINT. Spacecraft: GRAB. ELINT satellite..

• Secor - . Nation: USA. Agency: USAF. Spacecraft: SECOR.

• Injun 2 - . Nation: USA. Agency: USAF. Spacecraft: Injun.

• Surcal - . Nation: USA. Agency: USAF. Class: Surveillance. Type: Radar calibration target. Spacecraft: Surcal.

• Anna 1A - . Payload: Anna 1A. Mass: 160 kg (350 lb). Nation: USA. Agency: US Army. Class: Earth. Type: Geodetic satellite. Spacecraft: Anna. Decay Date: 1962-05-10 . USN, USAF, US Army, NASA joint program..

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

• Transit 5BN-1 - . Mass: 70 kg (154 lb). Nation: USA. Agency: USN. Program: Transit. Class: Navigation. Type: Navigation satellite. Spacecraft: Transit. USAF Sat Cat: 670 . COSPAR: 1963-038B. Apogee: 1,125 km (699 mi). Perigee: 1,066 km (662 mi). Inclination: 90.10 deg. Period: 107.20 min.

  The first Thor/Ablestar launch from Vandenberg carried a Navy payload that became the first satellite to be operated completely with nuclear power. A SNAP-9A satellite nuclear power supply, built by the Martin Company and the Atomic Energy Commission, was used to power the satellite. 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.

• Transit 5E-1 - . Payload: APL SN 39. Mass: 61 kg (134 lb). Nation: USA. Agency: USN. Program: Transit. Class: Earth. Type: Magnetosphere satellite. Spacecraft: Transit. USAF Sat Cat: 671 . COSPAR: 1963-038C. Apogee: 1,123 km (697 mi). Perigee: 1,065 km (661 mi). Inclination: 90.10 deg. Period: 107.10 min.

  The first Thor/Ablestar launch from Vandenberg carried a Navy payload that became the first satellite to be operated completely with nuclear power. A SNAP-9A satellite nuclear power supply, built by the Martin Company and the Atomic Energy Commission, was used to power the satellite. 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.

• Transit 5BN-2 - . Mass: 75 kg (165 lb). Nation: USA. Agency: USN. Program: Transit. Class: Navigation. Type: Navigation satellite. Spacecraft: Transit. USAF Sat Cat: 704 . COSPAR: 1963-049B. Apogee: 1,110 km (680 mi). Perigee: 1,061 km (659 mi). Inclination: 90.10 deg. Period: 107.00 min.

  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.

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

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

• Transit 5E-4 - . Mass: 55 kg (121 lb). Nation: USA. Agency: USN. Program: Transit. Class: Earth. Type: Magnetosphere satellite. Spacecraft: Transit. COSPAR: F640421B. Radiation monitoring..

• Transit O-1 - . Payload: NNS 30010 / Ablestar 016 / OPS 5798. Mass: 60 kg (132 lb). Nation: USA. Agency: USN. Program: Transit. Class: Navigation. Type: Navigation satellite. Spacecraft: Transit. USAF Sat Cat: 897 . COSPAR: 1964-063B. Apogee: 1,077 km (669 mi). Perigee: 1,046 km (649 mi). Inclination: 90.20 deg. Period: 106.40 min. Naval Avionics Facility-assembled production spacecraft. Failed after a few days operation..

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

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

• Transit 5E-5 - . Payload: APL SN 43 / OPS 6582. Mass: 78 kg (171 lb). Nation: USA. Agency: USN. Program: Transit. Class: Earth. Type: Magnetosphere satellite. Spacecraft: Transit. USAF Sat Cat: 959 . COSPAR: 1964-083C. Apogee: 1,064 km (661 mi). Perigee: 1,007 km (625 mi). Inclination: 89.80 deg. Period: 105.90 min. Celestial UV, magnetic field data..

• Transit O-2 - . Payload: NNS 30020 / OPS 6582. Mass: 60 kg (132 lb). Nation: USA. Agency: USN. Program: Transit. Class: Navigation. Type: Navigation satellite. Spacecraft: Transit. USAF Sat Cat: 965 . COSPAR: 1964-083D. Apogee: 1,079 km (670 mi). Perigee: 1,020 km (630 mi). Inclination: 89.80 deg. Period: 106.20 min. Naval Avionics Facility-assembled production spacecraft. Failed after a few days operation..

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

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

• Transit O-4 - . Payload: NNS 30040 / OPS 8480. Mass: 61 kg (134 lb). Nation: USA. Agency: USN. Program: Transit. Class: Navigation. Type: Navigation satellite. Spacecraft: Transit. USAF Sat Cat: 1420 . COSPAR: 1965-048A. Apogee: 1,125 km (699 mi). Perigee: 1,016 km (631 mi). Inclination: 90.10 deg. Period: 106.60 min. 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..

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

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

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

• Transit O-5 - . Payload: NNS 30050 / OPS 8464. Mass: 61 kg (134 lb). Nation: USA. Agency: USN. Program: Transit. Class: Navigation. Type: Navigation satellite. Spacecraft: Transit. USAF Sat Cat: 1514 . COSPAR: 1965-065F. Apogee: 1,183 km (735 mi). Perigee: 1,078 km (669 mi). Inclination: 89.90 deg. Period: 107.90 min. Naval Avionics Facility-assembled production spacecraft. Failed after a few weeks operation..

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

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