HawkEye 360 constellation

The HawkEye 360 constellation is an operational commercial RF geolocation system operated by HawkEye 360. The first cluster, known as the Pathfinder, launched on 3 December 2018; by March 2026 fourteen clusters totalling 42 satellites had been deployed, with further clusters under contract.^[1] The Pathfinder model is part of the permanent collection of the Smithsonian National Air and Space Museum.^[2]

Each satellite is built on the Space Flight Laboratory NEMO-15 microsatellite bus, measuring approximately 20x26.7x44 cm and massing around 13.4 kg.^[3][2] Satellites fly in three-satellite formation clusters with approximately 125 km along-track spacing, collecting RF signals across a frequency range from 70 MHz to approximately 18 GHz.^[2] Time-of-arrival and frequency-of-arrival multilateration across the formation is used to geolocate RF emitters on the ground and at sea.^[2] Cluster 11, launched in December 2024, features upgraded payloads with expanded bandwidth and multi-band signal capture capability.^[2]

Most clusters fly in Sun-synchronous orbits between 485 and 598 km altitude, within FCC-authorised limits of 475 to 615 km; Clusters 8 and 11 fly at 45-degree inclination to broaden temporal revisit diversity.^[4][2] Launch vehicles have included SpaceX Falcon 9 Transporter and Bandwagon rideshare missions and Rocket Lab Electron.^[1][2]

The constellation is used for maritime domain awareness including vessel tracking via AIS and non-cooperative RF emissions, detection and geolocation of GNSS interference sources, spectrum monitoring, illegal fishing detection, search and rescue beacon location, and defence domain awareness.^[5][2]