The Naval Ocean Surveillance System (NOSS) is a series of signals intelligence satellites that have conducted electronic signals intelligence for the U.S. Navy since the early 1970s. The first series of satellites were codenamed "White Cloud" or "PARCAE", while second and third-generation satellites have used the codenames "Ranger" and "Intruder".
The system is operated by the United States Navy and its main purpose was tactical geolocation of Soviet Navy assets during the Cold War. The NOSS satellites operate in clusters in low Earth orbit to detect radar and other electronic transmissions from ships at sea and locate them using the Time Difference of Arrival technique.
|Name||ID||Launch date||Launch vehicle||Launch site||NROL designation||Perigee||Apogee||Inclination||Remarks|
|OPS 6431 SSU-1||1976-038C||30 April 1976||Atlas E/F-MSD||VAFB, SLC-3W||N/A||1,092 km||1,128 km||63.5°||Dispenser designated OPS 6431 and catalogued as 1976-038A.|
|OPS 6431 SSU-2||1976-038D|
|OPS 6431 SSU-3||1976-038J|
|OPS 8781 SSU-1||1977-112D||8 December 1977||Atlas E/F-MSD||VAFB, SLC-3W||1,054 km||1,169 km||63.4°||Dispenser designated OPS 8781 and catalogued as 1977-112A.|
|OPS 8781 SSU-2||1977-112E|
|OPS 8781 SSU-3||1977-112F|
|OPS 7245 SSU-1||1980-019C||3 March 1980||Atlas E/F-MSD||VAFB, SLC-3W||1,035 km||1,150 km||63.0°||Dispenser designated OPS 7245 and catalogued as 1980-019A.|
|OPS 7245 SSU-2||1980-019D|
|OPS 7245 SSU-3||1980-019G|
|OPS 3255 SSU-1||N/A||9 December 1980||Atlas E/F-MSD||VAFB, SLC-3W||Failed to orbit||Dispenser designated OPS 3255, loss of control after engine failure, followed by explosion.|
|OPS 3255 SSU-2||N/A|
|OPS 3255 SSU-3||N/A|
|OPS 0252 SSU-1||1983-008E||9 February 1983||Atlas H-MSD||VAFB, SLC-3E||1,063 km||1,186 km||63.40°||Dispenser designated OPS 0252 and catalogued as 1983-008A.|
|OPS 0252 SSU-2||1983-008F|
|OPS 0252 SSU-3||1983-008H|
|OPS 6432 SSU-1||1983-056C||9 June 1983||Atlas H-MSD||VAFB, SLC-3E||851 km||1,363 km||63.4°||Dispenser designated OPS 6432 and catalogued as 1983-056A.|
|OPS 6432 SSU-2||1983-056D|
|OPS 6432 SSU-3||1983-056G|
|OPS 8737 SSU-1||1984-012C||5 February 1984||Atlas H-MSD||VAFB, SLC-3E||1,052 km||1,172 km||63.4°||Dispenser designated OPS 8737 and catalogued as 1984-012A.|
|OPS 8737 SSU-2||1984-012D|
|OPS 8737 SSU-3||1984-012F|
|USA-16||1986-014C||9 February 1986||Atlas H-MSD||VAFB, SLC-3E||1,049 km||1,166 km||63.0°||Dispenser designated USA-15 and catalogued as 1986-014A.|
|USA-23||1987-043E||15 May 1987||Atlas H-MSD||VAFB, SLC-3E||1,045 km||1,179 km||62.9°||Dispenser designated USA-22 and catalogued as 1987-043A.|
|USA-60||1990-050E||8 June 1990||Titan IV(405)A||CCAFS, LC-41||N/A||1,071 km||1,146 km||63.4°||Dispenser designated USA-59 and catalogued as 1990-050A.|
|USA-74||1991-076C||8 November 1991||Titan IV(403)A||VAFB, SLC-4E||1,052 km||1,164 km||63.4°||Dispenser designated USA-72 and catalogued as 1991-076A.|
|Unnamed||N/A||2 August 1993||Titan IV(403)A||VAFB, SLC-4E||Failed to orbit||Exploded due to crack in solid rocket motor caused by poor repair.|
|USA-119||1996-029A||12 May 1996||Titan IV(403)A||VAFB, SLC-4E||1,050 km||1,166 km||63.4°||Dispenser designated USA-122 and catalogued as 1996-029D.|
|USA-160||2001-040A||8 September 2001||Atlas IIAS||VAFB, SLC-3E||NROL-13||1,100 km||1,100 km||63.0°|
|USA-173||2003-054A||2 December 2003||Atlas IIAS||VAFB, SLC-3E||NROL-18||1,013 km||1,200 km||63.4°|
|USA-181||2005-004A||3 February 2005||Atlas IIIB||CCAFS, SLC-36B||NROL-23||1,011 km||1,209 km||63.4°|
|USA-194||2007-027A||15 June 2007||Atlas V 401||CCAFS, SLC-41||NROL-30||1,053 km||1,163 km||63.4°||Launched into lower orbit than planned, spacecraft corrected under own power, at expense of operational life.|
|USA-229||2011-014A||15 April 2011||Atlas V 411||VAFB, SLC-3E||NROL-34||1,015 km||1,207 km||63.46°|
|USA-238||2012-048A||13 September 2012||Atlas V 401||VAFB, SLC-3E||NROL-36||1,056 km||1,158 km||63.4°|
|USA-264||2015-058A||8 October 2015||Atlas V 401||VAFB, SLC-3E||NROL-55||1,013 km||1,201 km||63.4°|
|USA-274||2017-011A||1 March 2017||Atlas V 401||VAFB, SLC-3E||NROL-79||1,010 km||1,204 km||63.4°|
|USA-3XX||2021-XXXA||December 2021 (planned)||Falcon 9 Block 5||CCAFS, SLC-40||NROL-85||1,100 km||1,100 km||63.4°||Awaiting a launch.|
- * One satellite from each third generation pair is officially catalogued as debris.
- data from , 
The costs of the NOSS satellites (excluding costs for the launch vehicle), which were destroyed in a Titan IV launch failure in 1993, were US$800 million (inflation adjusted US$ 1.4 billion in 2021).
- "Display: SSU 1/2 1976-038C". NASA. 14 May 2020. Retrieved 29 October 2020. This article incorporates text from this source, which is in the public domain.
- "NOSS Double and Triple Satellite Formations". satobs.org.
- Weiner, Tim (4 August 1993). "Titan Lost Payload: Spy-Satellite System Worth $800 Million". The New York Times.