U.S. Space Force Expands Surveillance Capabilities with Second Sensor in Japanese Constellation

## U.S. Space Force Expands Surveillance Capabilities with Second Sensor in Japanese Constellation The U.S. Space Force has completed the deployment of two space-surveillance sensors aboard Japanese navigation satellites, expanding its ability to monitor objects in geosynchronous orbit. This achievement is part of a bilateral program that utilizes allied spacecraft and launch systems to field U.S. military payloads. The second sensor was deployed aboard the Quasi-Zenith Satellite 7 (QZS-7) on August 10, following the launch of the first U.S. sensor aboard Japan's QZS-6 satellite on February 2, 2025. The QZS-7 was launched using Japan's H3 rocket, which is part of the Quasi-Zenith Satellite System-Hosted Payload program (QZSS-HP). This program is a national security space partnership established by the United States and Japan under a 2020 agreement. ## A Deeper Form of Allied Space Cooperation The U.S. sensors perform a separate mission from the satellites' navigation payloads, providing the Space Force with additional vantage points for observing spacecraft at high altitudes. This represents a deeper form of allied space cooperation than simply exchanging surveillance data. A U.S.-owned operational military sensor is integrated with a Japanese government spacecraft, launched aboard a Japanese rocket, and then incorporated into the U.S. military's space domain awareness architecture. The U.S.-owned space domain awareness payload was designed and built by the Massachusetts Institute of Technology's Lincoln Laboratory and was integrated and tested with its Japanese host satellite over a two-year period before launch. The sensor was placed in geosynchronous orbit over the Indo-Pacific region, and its observations will be fed in near real-time into the U.S. Space Surveillance Network. This network is used by the military to detect, track, and characterize satellites and other objects in orbit. According to Col. Gina Peterson, deputy commander of Mission Delta 2 - Space Domain Awareness, "QZSS-HP is a key contributor to help us meet the threat of peer adversaries in space and build towards resilient capabilities to detect, understand, and maintain custody of objects in deep space." The program represents a significant expansion of the U.S. Space Force's surveillance capabilities and demonstrates the growing cooperation between the U.S. and Japan in the field of space security.