US Space Force sensors have been launched on a Japanese satellite, marking the second of two planned payloads designed to monitor activity in space above the Indo-Pacific.
According to Space Systems Command, the paired missions constitute the first bilateral US-Japan cooperative space effort focused on national security. The first of the two sensors launched in February 2025.
The US Space Force sensors, designed and built by the Massachusetts Institute of Technology’s Lincoln Laboratory, will support vigilance over the Indo-Pacific region, according to the command.
The latest payload rode aboard Quasi-Zenith Satellite-7, or QZS-7, which lifted off on an H-3 launch vehicle from Tanegashima Space Center in Japan on Aug. 10. The satellite was built by Mitsubishi Electric Corporation.
QZS-7 is the seventh and final spacecraft in the Quasi-Zenith Satellite System constellation in geosynchronous Earth orbit. Operated by the Japan Aerospace Exploration Agency, the network serves as Japan’s version of GPS and provides position, navigation, and timing services for civilian and military users.
The Pentagon initiated the arrangement in 2019 to host US payloads on the sixth and seventh QZSS satellites as part of a broader set of agreements to deepen space situational awareness cooperation with Japan.
Funding for the program began in fiscal 2021, with plans for QZS-6 to launch in calendar year 2023 and QZS-7 to follow the next year.
The two US Space Force sensors will supply tracking data to the Space Surveillance Network, a system of ground-based radars and telescopes on Earth and in orbit. The network is operated by the 18th Space Defense Squadron, headquartered at Vandenberg Space Force Base in California.
US Space Force sensors strengthen Indo-Pacific monitoring
The added coverage from the QZSS-hosted payloads is intended to bolster awareness of objects and activity in geosynchronous orbit across the Indo-Pacific, complementing existing US and allied capabilities.
The program aligns with broader Pentagon efforts to enhance sensing and tracking architectures, including initiatives like FBM Radar Next.