Naval Ocean Surveillance System

Satellites

The first generation of NOSS satellites was developed by the Naval Research Laboratory (NRL), building on earlier electronic listening satellites Grab (1960–1962) and Poppy (1962–1971). Between 1976 and 1987, eight clusters of three satellites were launched, each carried by an Atlas F, E, or H rocket. A dispenser with a solid propellant engine placed the three sub-satellites into an operational orbit of 1,050 × 1,150 km at an inclination of 63°, maintaining a triangular formation with inter-satellite distances between 30 and 240 km. Each satellite carried antennas on one face, kept pointed toward Earth, and used a gravity-gradient boom 10 to 15 meters long for orientation.

The second generation, first launched in 1990, kept the same configuration. Clusters of three were launched using a Titan Launch Dispenser (TLD) that positioned them in a 1,100 × 1,100 km orbit at 63.4° inclination.

Four NOSS-2 cluster launches occurred between 1990 and 1996, with one failure in 1993. These heavier satellites required a Titan IV rocket. After ejecting the satellites, the dispenser moved to an elliptical orbit (1,100 × 9,000 km) where a Satellite Launch Dispenser Communications System (SLDCOM) module handled tactical military telecommunications.

The third generation, deployed after 2001, operates in pairs without a dispenser. Each pair has a combined mass of 6,500 kg and occupies a 1,100 × 1,100 km orbit at 64° inclination. Eight pairs were launched between 2001 and 2017 using Atlas II, Atlas III, and Atlas V rockets. One satellite from each third-generation pair is officially catalogued as debris.