Directory of U.S. Military Rockets and Missiles
Appendix 3: Space Vehicles
Copyright © 2003-2009 Jos Heyman
 (HTML formatting by Andreas Parsch) 

Boeing (Rockwell) NS-7 Navstar GPS

The designation NS-7A referred to the Navstar series of navigational satellite also known as Navigational Development Satellite (NDS) and the Global Positioning System (GPS). The satellites were developed for the US Navy by Rockwell and four satellites provided a positional fix with an accuracy of 30 m. It was also made available to civilian users. The 525 kg Navstar satellites were fitted with three rubidium clocks and one caesium clock. They transmitted at 1575.42 MHz for civilian users and at 1227.6 MHz for military users.

Image: Author's collection
Navstar-1 (1978 020A)

Name Intl. Designation Launch Re-entry Notes
Navstar-11978 020A22-Feb-1978 Also known as Ops-5111
Navstar-21978 047A13-May-1978 Also known as Ops-5112
Navstar-31978 093A7-Oct-1978 Also known as Ops-5113
Navstar-41978 112A11-Dec-1978 Also known as Ops-5114
Navstar-51980 011A9-Feb-1980 Also known as Ops-5117
Navstar-61980 032A26-Apr-1980 Also known as Ops-5118
Navstar-7---18-Dec-1981---Failed to orbit
Navstar-81983 072A14-Jul-1983 Also known as Ops-9794
Navstar-91984 059A13-Jun-1984 Also known as USA-1
Navstar-101984 097A8-Sep-1984 Also known as USA-5
Navstar-111985 093A9-Oct-1985 Also known as USA-10

Launch dates of the Navstar series

The Navstar 2 system, designated as NS-7B, was also built by Rockwell. The operational system consisted of 21 satellites. Each 1665 kg satellite was equipped with an atomic clock with an accuracy of 1 second in 300,000 years. The transmissions were at 1575.42 MHz for civilian purposes and 1227.6 MHz for military purposes.

Image: Author's collection
Navstar 2-1 (1989 013A)

Name Intl. Designation Launch Re-entry Notes
Navstar 2-11989 013A14-Feb-1989 Also known as USA-35
Navstar 2-21989 044A10-Jun-1989 Also known as USA-38
Navstar 2-31989 064A18-Aug-1989 Also known as USA-42
Navstar 2-41989 085A21-Oct-1989 Also known as USA-47
Navstar 2-51989 097A11-Dec-1989 Also known as USA-49
Navstar 2-61990 008A24-Jan-1990 Also known as USA-50
Navstar 2-71990 025A26-Mar-1990 Also known as USA-54
Navstar 2-81990 068A2-Aug-1990 Also known as USA-63
Navstar 2-91990 088A1-Oct-1990 Also known as USA-64

Launch dates of the Navstar 2 series

The Navstar 2A series, designated as NS-7C, was similar to the Navstar 2 series but carried improved instrumentation.

Name Intl. Designation Launch Re-entry Notes
Navstar 2A-11990 103A26-Nov-1990 Also known as USA-66
Navstar 2A-21991 047A4-Jul-1991 Also known as USA-71
Navstar 2A-31992 009A23-Feb-1992 Also known as USA-79
Navstar 2A-41992 019A10-Apr-1992 Also known as USA-80
Navstar 2A-51992 039A7-Jul-1992 Also known as USA-83
Navstar 2A-61992 058A9-Sep-1992 Also known as USA-84
Navstar 2A-71992 079A23-Nov-1992 Also known as USA-85
Navstar 2A-81992 089A18-Dec-1992 Also known as USA-87
Navstar 2A-91993 007A3-Feb-1993 Also known as USA-88
Navstar 2A-101993 017A30-Mar-1993 Also known as USA-90
Navstar 2A-111993 032A13-May-1993 Also known as USA-91
Navstar 2A-121993 042A26-Jun-1993 Also known as USA-92
Navstar 2A-131993 054A30-Aug-1993 Also known as USA-94
Navstar 2A-141993 068A26-Oct-1993 Also known as USA-96
Navstar 2A-151994 016A10-Mar-1994 Also known as USA-100
Navstar 2A-161996 019A28-Mar-1996 Also known as USA-117
Navstar 2A-171996 041A16-Jul-1996 Also known as USA-126
Navstar 2A-181996 056A12-Sep-1996 Also known as USA-128
Navstar 2A-191997 067A5-Nov-1997 Also known as USA-134

Launch dates of the Navstar 2A series

Further improvements to the instrumentation was introduced with the Navstar 2R ("R" for "replenishment") series, which was also designated as NS-7D. Whilst these satellites used the original Rockwell design, they were in fact built by Lockheed Martin. Navstar 2R-M was a "modernised" version (hence the "M") of the 2R series. The series used the remaining eight unlaunched 2R satellites but converted with increased power for existing signals and two new military signals as well as a second civilian signal, along with a redesigned external antenna panel and more efficient transmitters. The mass of the satellites increased by 28 kg to 2073 kg.

Image: Lockheed Martin

Name Intl. Designation Launch Re-entry Notes
Navstar 2R-1---17-Jan-1997--- Failed to orbit
Navstar 2R-21997 035A23-Jul-1997 Also known as USA-132
Navstar 2R-31999 055A7-Oct-1999 Also known as USA-145
Navstar 2R-42000 025A11-May-2000 Also known as USA-150
Navstar 2R-52000 040A16-Jul-2000 Also known as USA-151
Navstar 2R-62000 071A10-Nov-2000 Also known as USA-154
Navstar 2R-72001 004A30-Jan-2001 Also known as USA-156
Navstar 2R-82003 005A29-Jan-2003 Also known as USA-166
Navstar 2R-92003 010A31-Mar-2003 Also known as USA-168
Navstar 2R-102003 058A21-Dec-2003 Also known as USA-175
Navstar 2R-112004 009A20-Mar-2004 Also known as USA-177
Navstar 2R-122004 023A23-Jun-2004 Also known as USA-178
Navstar 2R-132004 045A6-Nov-2004 Also known as USA-180
Navstar 2R-142005 038A26-Sep-2005 Also known as USA-183
Navstar 2R-152006 042A26-Sep-2006 Also known as USA-190
Navstar 2R-162006 052A17-Nov-2005 Also known as USA-192
Navstar 2R-172007 047A17-Oct-2007 Also known as USA-196
Navstar 2R-182007 062A20-Dec-2007 Also known as USA-199
Navstar 2R-192008 012A15-Mar-2008 Also known as USA-201

Launch dates of the Navstar 2R series

The designation NS-7E refers to the Navstar 2F series of satellites. Boeing (which now owns Rockwell) has received an order to build six against a requirement of 33 by 2012. As it is recognised that over the years that the Navstar 2F series will be launched, technology and needs will change, Boeing has adopted a modular approach which will allow them to meet those changes.

Image: Boeing

Background history

Navigational satellites are essentially radio transmitters of which the orbital positions are known. Through analysing the signals from three satellites, a navigator is not only able to determine his longitude and latitude but also, where appropriate, his altitude.

The early navigational satellites in the Transit series used a radio-Doppler navigation method in which the ship's position was calculated from the observed change in the received frequency of the satellite radio transmission as the satellite passes across the sky. This technique is based on the principle that the orbit of a satellite can be accurately computed by the analysis of the Doppler shift of the radio transmissions by the satellites. The accuracy is, however, limited by the frequency stability of the satellite transmissions and the ability to predict the satellite's orbit between the time it is measured by a ground tracking station and the time the user observed the satellite.

Another method is based on time ranging. Here the user calculates his distance from a satellite by a measurement of the time that the radio signal of the satellite takes to cover the distance to the receiver. To achieve a reasonable accuracy, this method requires three separate satellites and a very accurate clock.

Transit series

The early navigational satellites of the United States were of an experimental nature. They were sponsored by the U.S. Navy and were built by RCA. The Transit-1A and -2 series carried two ultrastable oscillators, an electronic clock and four frequency transmitters which operated in the 162/216 MHz and 53/324 MHz bands. Transit-3 carried in addition a small magnetic memory. The Transit-4 series, which was of a different design, was unique in that they carried a Supplementary Nuclear Power (SNAP) source to generate the satellite's power requirements. Transmitters operated at 150/400 MHz. The Transit-5 series satellites were of an octagonal shape and carried dual frequency transmitters as well as a 30 m gravity gradient stabilisation boom. The 5A sub-series were powered by solar cells whilst the 5B sub-series carried a SNAP-9A nuclear power source. The 5C sub-series reverted again to solar cells.

Image: Author's collection
Transit-5C1 (1964 026A)

Name Intl. Designation Launch Re-entry Notes
Transit-1A---17-Sep-1959--- Failed to orbit
Transit-1B1960 γ213-Apr-19605-Oct-1967 
Transit-2A1960 η122-Jun-1960  
Transit-3A---30-Nov-1960--- Failed to orbit
Transit-3B1961 η121-Feb-196130-Mar-1961 Failed to separate from Lofti-1
Transit-4A1961 ο129-Jun-1961  
Transit-4B1961 αη115-Nov-1961  
Transit-5A11962 βψ119-Dec-196225-Sep-1986 
Transit-5A2---5-Apr-1963--- Also known as Ops-0804; failed to orbit
Transit-5A31963 022A16-Jun-19633-Aug-1990 
Transit-5BN11963 038B28-Sep-1963  
Transit-5BN21963 049B5-Dec-1963  
Transit-5BN3---21-Apr-1964--- Failed to orbit
Transit-5C11964 026A4-Jun-1964 Also known as Ops-4412

Launch dates of the Transit series


The Navy Navigational Satellite System (NNSS), also called Oscar or Transit-O, was the first operational system. The principal objective was to provide positioning facilities with an accuracy of 150 m to submarines carrying Polaris missiles. At a later stage the system was also made available to civilian users. The satellites transmitted at 150 MHz and 400 MHz. Whilst six satellites provide a useful coverage, additional satellites have been launched as in-orbit spares. The satellites had an initial mass of 32 kg and in total 32 were built by RCA. They have been identified by the third and fourth characters in the numeric designation whilst the meaning of the numeric '3' is not known.

A number of the satellites were converted for other uses as Transat (#11), P76-5 (#15), Hilat (#16) and Polar Bear (#17). Spacecraft #22 was used in 1992 ground tests to assess the impact of aluminium projectiles bombarded onto the spacecraft structure. Of the remaining spacecraft #21, #26 and #28, one was given to Naval Post Graduate School and two went to the Applied Research Laboratory of the University of Texas, Austin. Of these three, one was destroyed in impact tests like spacecraft #22. The satellites launched in the 1985/88 period are sometimes referred to as Stacked Oscar On Scout (SOOS).

Image: Author's collection
NNSS-30010 (1964 063B)

Name Intl. Designation Launch Re-entry Notes
NNSS-300101964 063B6-Oct-1964 Also known as Ops-5798
NNSS-300201964 083D12-Dec-1964 Also known as Ops-6582
NNSS-300301965 017A11-Mar-196514-Jun-1965 Also known as Ops-7087
NNSS-300401965 048A24-Jun-1965 Also known as Ops-8480
NNSS-300501965 065F13-Aug-1965 Also known as Ops-8464
NNSS-300601965 109A21-Dec-1965 Also known as Ops-1509
NNSS-300701966 005A28-Jan-1966 Also known as Ops-1593
NNSS-300801966 024A26-Mar-1966 Also known as Ops-1117
NNSS-300901966 041A19-May-1966 Also known as Ops-0082
NNSS-301001966 076A18-Aug-1966 Also known as Ops-2366
NNSS-30110---------Used as Transat
NNSS-301201967 034A14-Apr-1967 Also known as Ops-0100
NNSS-301301967 048A18-May-1967 Also known as Ops-7218
NNSS-301401967 092A25-Sep-1967 Also known as Ops-4947
NNSS-30150---------Used as P76-5
NNSS-30160---------Used as Hilat
NNSS-30170---------Used as Polar Bear
NNSS-301801968 012A2-Mar-1968 Also known as Ops-7034
NNSS-301901970 067A27-Aug-1970  
NNSS-302001973 081A30-Oct-1973  
NNSS-30210---------Not used
NNSS-30220--------- Expended in tests, 1992
NNSS-302301988 033A26-Apr-1988  
NNSS-302401985 066A3-Aug-1985  
NNSS-302501988 074A25-Aug-1988  
NNSS-30260---------Not used
NNSS-302701987 080A16-Sep-1987  
NNSS-30280---------Not used
NNSS-302901987 080B16-Sep-1987  
NNSS-303001985 066B3-Aug-1985  
NNSS-303101988 074B25-Aug-1988  
NNSS-303201988 033B26-Apr-1988  

Launch dates of the NNSS series


The Timation or Navigation Technology Satellites (NTS) series tested new equipment to be used in the Global Positioning System (GPS). Timation-1 carried two high-precision quartz clocks for accurate measurements based on a three dimensional navigation technique. Timation-2 carried improved equipment and a dual frequency transmitter operating at 150/400 MHz. In addition Timation-3 or NTS-1 carried two rubidium vapor atomic clocks and operated at the 335 MHz and 1580 MHz frequencies whilst NTS-2 tested a ceasium clock. The satellite also carried an experimental solar array.

Image: Author's collection
Timation-1 (1967 053E)

Name Intl. Designation Launch Re-entry Notes
Timation-11967 053E31-May-1967  
Timation-21969 082A30-Sep-196930-Oct-1970 Also known as Ops-7613
Timation-31974 054A14-Jul-1974 Also known as NTS-1 and Ops-7518
NTS-21977 053A23-Jun-1977  

Launch dates of the Timation/NTS series


The satellites in the Transit Improvement Program (TIP) were considered as a precursor to the Nova series and incorporated the Disturbance Compensating System (Discos), hence Transit Improved And Discos (Triad), which was designed to maintain position in orbit by correcting disturbances caused by solar wind and atmospheric resistance. In addition TIP-1 carried a radio-isotope thermal generator.

Name Intl. Designation Launch Re-entry Notes
TIP-11972 069A2-Sep-1972 Also known as Triad
TIP-21975 099A12-Oct-197526-May-1991 
TIP-31976 089A1-Sep-197630-May-1981 

Launch dates of the TIP series


The Nova military navigational satellite had a mass of 166 kg and tested new instruments and techniques. They also carried a tri-axis vector magnetometer, four solar detectors and an internal mass displacement detector.

Image: Author's collection
Nova-1 (1981 044A)

Name Intl. Designation Launch Re-entry Notes
Nova-11981 044A15-May-1981 Also known as NNSS 30480
Nova-21988 052A16-Jun-1988 Also known as NNSS 30490
Nova-31984 110A12-Oct-1984 Also known as NNSS 30450

Launch dates of the Nova series

Back to Directory of U.S. Military Rockets and Missiles, Appendix 3

Last Updated: 25 June 2009