Directory of U.S. Military Rockets and Missiles
Appendix 3: Space Vehicles
Copyright © 2003-2009 Jos Heyman
Updates © 2024 Andreas Parsch

Boeing (Rockwell) NS-7 Navstar GPS

GPS Block I

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 Notes
Navstar-11978-020A22-Feb-1978Also known as Ops-5111
Navstar-21978-047A13-May-1978Also known as Ops-5112
Navstar-31978-093A 7-Oct-1978Also known as Ops-5113
Navstar-41978-112A11-Dec-1978Also known as Ops-5114
Navstar-51980-011A 9-Feb-1980Also known as Ops-5117
Navstar-61980-032A26-Apr-1980Also known as Ops-5118
Navstar-7---18-Dec-1981Failed to orbit
Navstar-81983-072A14-Jul-1983Also known as Ops-9794
Navstar-91984-059A13-Jun-1984Also known as USA-1
Navstar-101984-097A8-Sep-1984Also known as USA-5
Navstar-111985-093A9-Oct-1985Also known as USA-10

Launch dates of the Navstar series

GPS Block II

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 Notes
Navstar 2-11989-013A14-Feb-1989Also known as USA-35
Navstar 2-21989-044A10-Jun-1989Also known as USA-38
Navstar 2-31989-064A18-Aug-1989Also known as USA-42
Navstar 2-41989-085A21-Oct-1989Also known as USA-47
Navstar 2-51989-097A11-Dec-1989Also known as USA-49
Navstar 2-61990-008A24-Jan-1990Also known as USA-50
Navstar 2-71990-025A26-Mar-1990Also known as USA-54
Navstar 2-81990-068A 2-Aug-1990Also known as USA-63
Navstar 2-91990-088A 1-Oct-1990Also 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 Notes
Navstar 2A-11990-103A26-Nov-1990Also known as USA-66
Navstar 2A-21991-047A 4-Jul-1991Also known as USA-71
Navstar 2A-31992-009A23-Feb-1992Also known as USA-79
Navstar 2A-41992-019A10-Apr-1992Also known as USA-80
Navstar 2A-51992-039A 7-Jul-1992Also known as USA-83
Navstar 2A-61992-058A 9-Sep-1992Also known as USA-84
Navstar 2A-71992-079A23-Nov-1992Also known as USA-85
Navstar 2A-81992-089A18-Dec-1992Also known as USA-87
Navstar 2A-91993-007A 3-Feb-1993Also known as USA-88
Navstar 2A-101993-017A30-Mar-1993Also known as USA-90
Navstar 2A-111993-032A13-May-1993Also known as USA-91
Navstar 2A-121993-042A26-Jun-1993Also known as USA-92
Navstar 2A-131993-054A30-Aug-1993Also known as USA-94
Navstar 2A-141993-068A26-Oct-1993Also known as USA-96
Navstar 2A-151994-016A10-Mar-1994Also known as USA-100
Navstar 2A-161996-019A28-Mar-1996Also known as USA-117
Navstar 2A-171996-041A16-Jul-1996Also known as USA-126
Navstar 2A-181996-056A12-Sep-1996Also known as USA-128
Navstar 2A-191997-067A 5-Nov-1997Also 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 Notes
GPS 2R-1---17-Jan-1997Failed to orbit
GPS 2R-21997-035A23-Jul-1997Also known as USA-132
GPS 2R-31999-055A 7-Oct-1999Also known as USA-145
GPS 2R-42000-025A11-May-2000Also known as USA-150
GPS 2R-52000-040A16-Jul-2000Also known as USA-151
GPS 2R-62000-071A10-Nov-2000Also known as USA-154
GPS 2R-72001-004A30-Jan-2001Also known as USA-156
GPS 2R-82003-005A29-Jan-2003Also known as USA-166
GPS 2R-92003-010A31-Mar-2003Also known as USA-168
GPS 2R-102003-058A21-Dec-2003Also known as USA-175
GPS 2R-112004-009A20-Mar-2004Also known as USA-177
GPS 2R-122004-023A23-Jun-2004Also known as USA-178
GPS 2R-132004-045A 6-Nov-2004Also known as USA-180
GPS 2RM-12005-038A26-Sep-2005ex GPS-2R-14; also known as USA-183
GPS 2RM-22006-042A26-Sep-2006ex GPS-2R-15; also known as USA-190
GPS 2RM-32006-052A17-Nov-2005ex GPS-2R-16; also known as USA-192
GPS 2RM-42007-047A17-Oct-2007ex GPS-2R-17; also known as USA-196
GPS 2RM-52007-062A20-Dec-2007ex GPS-2R-18; also known as USA-199
GPS 2RM-62008-012A15-Mar-2008ex GPS-2R-19; also known as USA-201
GPS 2RM-72009-014A24-Mar-2009ex GPS-2R-20; also known as USA-203
GPS 2RM-82009-043A07-Aug-2009ex GPS-2R-21; also known as USA-206

Launch dates of the GPS 2R (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

Name Intl. Designation Launch Notes
GPS 2F-12010-022A28-May-2010Also known as USA-213
GPS 2F-22011-036A16-Jul-2011Also known as USA-232
GPS 2F-32012-053A04-Oct-2012Also known as USA-239
GPS 2F-42013-023A15-May-2013Also known as USA-242
GPS 2F-52014-008A21-Feb-2014Also known as USA-248
GPS 2F-62014-026A17-May-2014Also known as USA-251
GPS 2F-72014-045A02-Aug-2014Also known as USA-256
GPS 2F-82014-068A29-Oct-2014Also known as USA-258
GPS 2F-92015-013A25-Mar-2015Also known as USA-260
GPS 2F-102015-033A15-Jul-2015Also known as USA-262
GPS 2F-112015-062A31-Oct-2015Also known as USA-265
GPS 2F-122016-007A05-Feb-2016Also known as USA-266

Launch dates of the GPS 2F (Navstar 2F) series


The third generation of GPS satellites is known as GPS Block III or simply GPS 3. Prime contractor is Lockheed Martin, building on their experience with the GPS 2R series. A total of 10 GPS Block III satellites is on order. A major improvement of the GPS 3 satellites are new navigation signals to increase availability and accuracy for civilian and military users. Additionally, the satellites have a directional antenna to transmit the latest military signal standard (called M-Code) with high power to a specific area on Earth.

Image: Lockheed Martin / USSF

Name Intl. Designation Launch Notes
GPS 3-12018-109A23-Dec-2018Also known as USA-289
GPS 3-22019-056A22-Aug-2019Also known as USA-293
GPS 3-32020-041A30-Jun-2020Also known as USA-304
GPS 3-42020-078A05-Nov-2020Also known as USA-309
GPS 3-52021-054A17-Jun-2021Also known as USA-319
GPS 3-62023-009A18-Jan-2023Also known as USA-343

Launch dates of the GPS 3 (Navstar 3) series

After the 10 Block III satellites, production will switch to the further improved Block IIIF. Current plans call for the launch of 22 Block IIIF satellites.

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-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-30210---------Not used
NNSS-30220--------- Expended in tests, 1992
NNSS-30260---------Not used
NNSS-30280---------Not used

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-21969-082A30-Sep-196930-Oct-1970 Also known as Ops-7613
Timation-31974-054A14-Jul-1974 Also known as NTS-1 and Ops-7518

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

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

Sources (for data after 2009)

[1] Wikipedia: GPS satellite blocks
[2] Gunter Krebs: Gunter's Space Page

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

Last Updated: 1 February 2024