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Transit-O (NNS, Oscar)

Transit-O [USN]

The Transit-O series of navigation satellites that closely followed the design of Transit 5C-1 were also called “Oscars” (Oscar is the phonetic alphabet for “O”, i. e., operational). They were also called NNS (Navy Navigation Satellite) or shortened NavSat.

The Transit-O series had one important change: Hysteresis rods were installed on the solar panels to dampen the residual motion after the satellite despin operation in orbit following launch).

The original plan was for the Oscar satellites to be built by the Naval Avionics Facility at Indianapolis (NAFI), and NAFI did build Oscars 1, 2, 3, 5, and 7. All except Oscar 3 reached orbit. However, the fabrication of the satellites did not meet specifications, and those that achieved orbit operated only a few weeks. After Oscars 1 and 2 failed to operate more than a few days, the Navy sponsor decided that APL would refurbish the subsystems built by NAFI for Oscars 4, 6, 8, 9, and 10, and then assemble and launch them. These satellites worked for 7 to 11 months in orbit. APL built Oscars 11 through 17 while the Navy sought a production contractor. Ultimately, RCA was selected and produced all satellites beginning with Oscar 18. The failures of Oscars 4, 6, 8, and 9 were due to several factors considered to be workmanship-related. For Oscar 10, a decrease in the number of solar cells available for charging the batteries was caused by thermal working of the solar cell interconnections as the satellite passed through the Sun and shade while orbiting the Earth. The problem was fixed on Oscar 12, which was the next operational satellite launched. Oscar 11 was not used at this time. It was later modified and launched as the satellite designated TRANSAT to perform related experiments. Beginning with Oscar 12, the satellites demonstrated an average orbital lifetime of more than 14 years. Two satellites, Oscars 13 and 20, operated for more than 20 years. Oscar 17 provides an interesting side note in the history of Transit. The satellite was turned over to the National Air and Space Museum in 1976 and was displayed to the public for more than 8 years. In 1984, it was refurbished at APL and launched as the Polar Bear (Polar Beacon Experiment and Auroral Research satellite) to collect data for studying communications over the Earth's polar regions. When the Navy contracted with RCA to build the Oscars, the satellite lifetimes were expected to be about 14 months. After RCA built Oscars 18 through 32, it became clear that the orbital lifetimes were much longer than anticipated so satellite production ceased. All unlaunched satellites were placed in containers for long-term storage at RCA. The row of gray containers became known as “the long gray line.”

By the late 1980s, the Scout-G1 rocket was able to launch about 260 lb into Transit's operational orbit. After a feasibility investigation by APL, the Navy awarded RCA a contract to launch two Oscar satellites on the same launch vehicle. This dual-launch method was called "stacked Oscars on Scout" (SOOS). This method allowed the remaining Transits to be stored in space and to be activated when needed.

Transit was superseded by the GPS 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).

Transit-O 22 was in 1992 intentionally destroyed on the ground in the Satellite Orbital debris Characterization Impact Test (SOCIT).

Nation: USA
Type / Application: Navigation
Operator: USN
Contractors: Naval Avionics Facility (#1-3, 5, 7); Johns Hopkins University Applied Physics Laboratory (APL) (#4, 6, 8-17); RCA (#18 - 32)
Equipment: ?
Configuration: Transit-Bus, Gravity Stabilized
Propulsion: ?
Power: 4 deployable fixed solar arrays, batteries
Satellite COSPAR Date LS Launch Vehicle Remarks
Transit-O 1 (NNS 30010, OPS 5798) 1964-063B 06.10.1964 Va 75-1-2 Thor-DSV2A Able-Star with Dragsphere 1, Dragsphere 2
Transit-O 2 (NNS 30020, OPS 6582) 1964-083D 13.12.1964 Va 75-1-2 Thor-DSV2A Able-Star with Transit-5E 5
Transit-O 3 (NNS 30030, OPS 7087) 1965-017A 11.03.1965 Va 75-1-1 P Thor-DSV2A Able-Star with SECOR 2
Transit-O 4 (NNS 30040, OPS 8480) 1965-048A 24.06.1965 Va 75-1-1 Thor-DSV2A Able-Star
Transit-O 5 (NNS 30050, OPS 8464) 1965-065F 13.08.1965 Va 75-1-1 Thor-DSV2A Able-Star with Tempsat 1, Dodecapole 2, Long Rod, Surcal 5, Calsphere 2
Transit-O 6 (NNS 30060, OPS 1509) 1965-109A 22.12.1965 Va PALC-D Scout-A
Transit-O 7 (NNS 30070, OPS 1593) 1966-005A 28.01.1966 Va PALC-D Scout-A
Transit-O 8 (NNS 30080, OPS 1117) 1966-024A 26.03.1966 Va PALC-D Scout-A
Transit-O 9 (NNS 30090, OPS 0082) 1966-041A 19.05.1966 Va PALC-D Scout-A
Transit-O 10 (NNS 30100, OPS 2366) 1966-076A 18.08.1966 Va SLC-5 Scout-A
Transit-O 11 (NNS 30110) - modified Transat
Transit-O 12 (NNS 30120, OPS 0100) 1967-034A 14.04.1967 Va SLC-5 Scout-A
Transit-O 13 (NNS 30130, OPS 7218) 1967-048A 18.05.1967 Va SLC-5 Scout-A
Transit-O 14 (NNS 30140, OPS 4947) 1967-092A 25.09.1967 Va SLC-5 Scout-A
Transit-O 15 (NNS 30150) - modified Wideband (P76-5)
Transit-O 16 (NNS 30160) - modified HILAT (P83-1)
Transit-O 17 (NNS 30170) - modified Polar Bear (P87-1)
Transit-O 18 (NNS 30180, OPS 7034) 1968-012A 02.03.1968 Va SLC-5 Scout-A
Transit-O 19 (NNS 30190, OPS 1999) 1970-067A 27.08.1970 Va SLC-5 Scout-A
Transit-O 20 (NNS 30200) 1973-081A 30.10.1973 Va SLC-5 Scout-A1
Transit-O 21 (NNS 30210) - not launched
Transit-O 22 (NNS 30220) - not launched destroyed in ground experiment
Transit-O 23 (NNS 30230, SOOS 3A) → NIMS 23 1988-033A 26.04.1988 Va SLC-5 Scout-G1 with Transit-O 32
Transit-O 24 (NNS 30240, SOOS 1A) 1985-066A 03.08.1985 Va SLC-5 Scout-G1 with Transit-O 30
Transit-O 25 (NNS 30250, SOOS 4A) → NIMS 25 1988-074A 25.08.1988 Va SLC-5 Scout-G1 with Transit-O 31
Transit-O 26 (NNS 30260) - not launched
Transit-O 27 (NNS 30270, SOOS 2A) → NIMS 27 1987-080A 16.09.1987 Va SLC-5 Scout-G1 with Transit-O 29
Transit-O 28 (NNS 30280) - not launched
Transit-O 29 (NNS 30290, SOOS 2B) → NIMS 29 1987-080B 16.09.1987 Va SLC-5 Scout-G1 with Transit-O 27
Transit-O 30 (NNS 30300, SOOS 1B) 1985-066B 03.08.1985 Va SLC-5 Scout-G1 with Transit-O 24
Transit-O 31 (NNS 30310, SOOS 4B) → NIMS 31 1988-074B 25.08.1988 Va SLC-5 Scout-G1 with Transit-O 25
Transit-O 32 (NNS 30320, SOOS 3B) → NIMS 32 1988-033B 26.04.1988 Va SLC-5 Scout-G1 with Transit-O 23

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