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Transit 2A
Transit 2A -

Credit: USN. 10,776 bytes. 249 x 234 pixels.



Class: Navigation. Nation: USA. Agency: U.S. Navy. Manufacturer: RCA.

In July 1964, the Navy put into operational service a system of spin-stabilized early Transit navigational satellites for precision position determination of Polaris missile submarines aid surface vessels. The system consists of 4 satellites, each weighing less than 45 kg, in near-circular orbits at 1000 km altitude. The satellites, originally known as Transit, were launched by the Scout booster. Early Transits carried a variety of piggy-back payloads, many still classified.

Operational Transit used a very different gravity-gradient design and was also known as the Navy Navigation Satellite (NNS) or OSCAR. The first OSCAR was launched by a 4-stage Scout May 19, 1966. The satellite was an octagonal prism, 0.37 m across and 0.25 m high with four blades of solar cells,each 1.67 m long and 0.25 m wide. The 65 kg satellite carried 2 transmitters for telemetering, doppler signals and memory read-out. All of the OSCAR spacecraft employ electromagnetic and gravity gradient stabilisation systems. Each also had a memory system for storing advance orbital data. Pulse signals in the memory system provided the satellites with a digital clock. Launched into polar orbits, at a general inclination of 90 degrees to the equator, the Oscar satellites circled the Earth at altitudes from 725 to 970 km. Prime Contractor was The Johns Hopkins University Applied Physics Laboratory. Associate Contractor, also responsible for manufacture of operational satellites, was Radio Corporation of America, Moorestown.

Transit provided continuous navigation satellite service from 1964, initially for Polaris submarines and later for civilian use. Transit receivers used the known characteristics of the satellites orbit, measured the Doppler shift of the satellite's radio signal, and thereby calculated the receivers position on the earth. Individual satellites operated for over 10 years. Technical breakthroughs during the program included gravity gradient stabilization, the use of radio-isotope thermoelectric generators (RTG), and navigation satellite technologies used in the later GPS series. The TRIAD satellite was launched in 1972 to test improvements, including a sensor designed to compensate for atmospheric drag and keep the satellite precisely in its orbit. This sensor used a mass floating inside a cavity. Small thrusters automatically fired to keep the floating mass in the middle of the cavity. Transit was superseded by the Navstar global positioning system. The use of the satellites for navigation was discontinued at the end of 1996, but the satellites continued transmitting and became the Navy Ionospheric Monitoring System (NIMS).


Specification

Total Length: 0.3 m. Maximum Diameter: 0.4 m. Total Mass: 65 kg.


Transit Chronology


17 September 1959 Transit 1A Program: Transit. Launch Site: Cape Canaveral . Launch Vehicle: Thor Able. FAILURE: Third stage failed. Mass: 119 kg.
13 April 1960 Transit 1B Program: Transit. Launch Site: Cape Canaveral . Launch Vehicle: Thor Able-Star. Mass: 121 kg. Perigee: 363 km. Apogee: 644 km. Inclination: 51.2 deg.

Navy TRANSIT I-B launched into orbit by Thor-Able-Star with navigation payload experiment at Cape Canaveral. Flight demonstrated the first engine restart in space and the feasibility of using satellites as navigational aids.


22 June 1960 Transit 2A Program: Transit. Launch Site: Cape Canaveral . Launch Vehicle: Thor Able-Star. Mass: 101 kg. Perigee: 604 km. Apogee: 988 km. Inclination: 66.7 deg.

Also returned geodetic data.


30 November 1960 Transit 3A Program: Transit. Launch Site: Cape Canaveral . Launch Vehicle: Thor Able-Star. FAILURE: Destroyed by range safety; launched with Solrad 2. Thor shut down too early. Failure. Mass: 91 kg.

Destroyed by range safety; launched with Solrad 2. Thor shut down too early.


22 February 1961 Lofti 1 Program: Transit. Launch Site: Cape Canaveral . Launch Vehicle: Thor Able-Star. Mass: 25 kg. Perigee: 188 km. Apogee: 983 km. Inclination: 28.3 deg.

Dual launch; failed to separate from Transit 3B. Partial Failure.


29 June 1961 Transit 4A Program: Transit. Launch Site: Cape Canaveral . Launch Vehicle: Thor Able-Star. Mass: 79 kg. Perigee: 865 km. Apogee: 986 km. Inclination: 66.8 deg.

Carried SNAP-3A nuclear power source.


15 November 1961 Transit 4B Program: Transit. Launch Site: Cape Canaveral . Launch Vehicle: Thor Able-Star. Mass: 86 kg. Perigee: 953 km. Apogee: 1,104 km. Inclination: 32.4 deg.

Carried SNAP 3 nuclear power source.


19 December 1962 Transit 5A Program: Transit. Launch Site: Vandenberg . Launch Vehicle: Scout X-3. Mass: 61 kg. Perigee: 336 km. Apogee: 347 km. Inclination: 90.6 deg.


Transit OperationalTransit Operational

Credit: USN. 33,451 bytes. 338 x 294 pixels.


Operational prototype; failed first day.
05 April 1963 Transit 5A-2 Program: Transit. Launch Site: Vandenberg . Launch Vehicle: Scout X-3. FAILURE: Failure. Mass: 84 kg.
16 June 1963 Transit 7 Program: Transit. Launch Site: Vandenberg . Launch Vehicle: Scout X-3. Mass: 55 kg. Perigee: 350 km. Apogee: 360 km. Inclination: 89.8 deg.
28 September 1963 Transit 5B-1 Program: Transit. Launch Site: Vandenberg . Launch Vehicle: Thor Able-Star. Mass: 70 kg. Perigee: 1,062 km. Apogee: 1,126 km. Inclination: 90.0 deg.
05 December 1963 Transit 5B-2 Program: Transit. Launch Site: Vandenberg . Launch Vehicle: Thor Able-Star. Mass: 75 kg. Perigee: 1,057 km. Apogee: 1,110 km. Inclination: 90.1 deg.

Carried SNAP-9A nuclear power source.


21 April 1964 Transit 5BN-3 Program: Transit. Launch Site: Vandenberg . Launch Vehicle: Thor Able-Star. FAILURE: Able-Star failed. Mass: 75 kg.

Carried SNAP-9A nuclear power source.


04 June 1964 Transit 9 Program: Transit. Launch Site: Vandenberg . Launch Vehicle: Scout X-4. Mass: 54 kg. Perigee: 825 km. Apogee: 898 km. Inclination: 90.5 deg.
06 October 1964 Transit 5B-4 NNS 30010 Program: Transit. Launch Site: Vandenberg . Launch Vehicle: Thor Able-Star. Mass: 60 kg. Perigee: 1,045 km. Apogee: 1,073 km. Inclination: 90.1 deg.
13 December 1964 Transit 5B-5 Program: Transit. Launch Site: Vandenberg . Launch Vehicle: Thor Able-Star. Mass: 60 kg. Perigee: 1,015 km. Apogee: 1,079 km. Inclination: 89.7 deg.
11 March 1965 Transit-O 3 Program: Transit. Launch Site: Vandenberg . Launch Vehicle: Thor Able-Star. Mass: 60 kg. Perigee: 191 km. Apogee: 418 km. Inclination: 90.0 deg.
24 June 1965 Transit 5B-6 Program: Transit. Launch Site: Vandenberg . Launch Vehicle: Thor Able-Star. Mass: 61 kg. Perigee: 1,015 km. Apogee: 1,124 km. Inclination: 90.1 deg.
13 August 1965 Transit 5B-7 Program: Transit. Launch Site: Vandenberg . Launch Vehicle: Thor Able-Star. Mass: 61 kg. Perigee: 1,075 km. Apogee: 1,183 km. Inclination: 90.0 deg.
22 December 1965 Transit 10 Program: Transit. Launch Site: Vandenberg . Launch Vehicle: Scout A. Mass: 60 kg. Perigee: 890 km. Apogee: 1,061 km. Inclination: 89.1 deg.
28 January 1966 Transit 11 Program: Transit. Launch Site: Vandenberg . Launch Vehicle: Scout A. Mass: 50 kg. Perigee: 849 km. Apogee: 1,183 km. Inclination: 89.9 deg.
26 March 1966 Transit 12 Program: Transit. Launch Site: Vandenberg . Launch Vehicle: Scout A. Mass: 50 kg. Perigee: 879 km. Apogee: 1,099 km. Inclination: 89.7 deg.
19 May 1966 Transit 13 Program: Transit. Launch Site: Vandenberg . Launch Vehicle: Scout A. Mass: 50 kg. Perigee: 833 km. Apogee: 951 km. Inclination: 90.1 deg.
18 August 1966 Transit 14 Program: Transit. Launch Site: Vandenberg . Launch Vehicle: Scout A. Mass: 58 kg. Perigee: 1,037 km. Apogee: 1,089 km. Inclination: 88.9 deg.
13 April 1967 Transit 15 Program: Transit. Launch Site: Vandenberg . Launch Vehicle: Scout A. Mass: 60 kg. Perigee: 1,037 km. Apogee: 1,064 km. Inclination: 90.1 deg.
02 March 1968 Transit 18 Program: Transit. Launch Site: Vandenberg . Launch Vehicle: Scout A. Mass: 60 kg. Perigee: 1,013 km. Apogee: 1,130 km. Inclination: 90.0 deg.
27 August 1970 Transit-O 19 Program: Transit. Launch Site: Vandenberg . Launch Vehicle: Scout A. Mass: 18 kg. Perigee: 944 km. Apogee: 1,202 km. Inclination: 90.0 deg.
30 October 1973 Transit-O 20 Program: Transit. Launch Site: Vandenberg . Launch Vehicle: Scout A-1. Mass: 58 kg. Perigee: 884 km. Apogee: 1,123 km. Inclination: 89.8 deg.
28 October 1977 Transit O-11 Program: Transit. Launch Site: Vandenberg . Launch Vehicle: Scout D. Mass: 94 kg. Perigee: 1,059 km. Apogee: 1,097 km. Inclination: 89.7 deg.
03 August 1985 Transit-O 30 Program: Transit. Launch Site: Vandenberg . Launch Vehicle: Scout G. Mass: 55 kg. Perigee: 999 km. Apogee: 1,255 km. Inclination: 89.9 deg.
16 September 1987 Transit-O 29 Program: Transit. Launch Site: Vandenberg . Launch Vehicle: Scout G. Mass: 59 kg. Perigee: 1,010 km. Apogee: 1,180 km. Inclination: 90.4 deg.
26 April 1988 Transit-O 23 Program: Transit. Launch Site: Vandenberg . Launch Vehicle: Scout G. Mass: 64 kg. Perigee: 1,013 km. Apogee: 1,301 km. Inclination: 90.3 deg.
25 August 1988 Transit-O 25 Program: Transit. Launch Site: Vandenberg . Launch Vehicle: Scout G. Mass: 59 kg. Perigee: 1,029 km. Apogee: 1,176 km. Inclination: 89.9 deg.

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Last update 12 March 2001.
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