Japan launched the second of two U.S. Space Force space-monitoring payloads aboard a Japanese satellite, completing a bilateral effort to collect information on objects in orbit above the Indo-Pacific. The hosted sensor traveled on Quasi-Zenith Satellite-7, or QZS-7, which lifted off Aug. 10 aboard an H-3 launch vehicle from the Tanegashima Space Center in Japan, Breaking Defense reported, citing a U.S. Space Systems Command statement.
The two missions represent what Space Systems Command described as the first U.S.-Japan bilateral space effort focused on national security. The sensors were designed and built by the Massachusetts Institute of Technology’s Lincoln Laboratory. Their role is to monitor activity in space above the Indo-Pacific region, according to the Space Systems Command release cited in the report.
The payload launched with QZS-7 is the second sensor in the planned pair. The first sensor was launched in February 2025. The two payloads are hosted on QZS-7 and its predecessor, QZS-6, and will provide data to the U.S. Space Surveillance Network.
The Space Surveillance Network combines ground-based radar and telescopes on Earth and in space. It is operated by the 18th Space Defense Squadron, which is headquartered at Vandenberg Space Force Base in California. Data from the hosted payloads will support the network’s monitoring of objects in orbit.
The Pentagon initiated the bilateral hosted-payload effort in 2019 as part of agreements intended to improve cooperation with Japan on space situational awareness. The U.S. Space Force began funding the program in fiscal 2021. The plan called for the sensors to be hosted on the sixth and seventh satellites in Japan’s Quasi-Zenith Satellite System constellation.
QZS-7 is the seventh and final satellite in the QZSS constellation stationed in geosynchronous Earth orbit. Mitsubishi Electric built the satellite, and the Japan Aerospace Exploration Agency operates the constellation. QZSS provides positioning, navigation and timing information for civilian and military users and serves as Japan’s version of GPS.
The program’s initial schedule anticipated that QZS-6 would launch in calendar 2023 and QZS-7 would launch the following year. The first sensor was launched in February 2025, and QZS-7 launched Aug. 10, 2026. The second launch places both planned U.S. sensors on Japanese QZSS satellites and extends the data-sharing arrangement between the two countries.
The QZS-7 mission therefore adds a new U.S. space-monitoring payload to a Japanese navigation satellite while linking the resulting observations to an existing U.S. surveillance network. The arrangement combines Japan’s QZSS constellation with U.S. Space Force monitoring capabilities over the Indo-Pacific, the area identified by Space Systems Command for the sensors’ mission.