A Japanese amateur radio satellite, launched to the International Space Station (ISS) last October, will soon be deployed in a higher orbit.
After delivering about 12,000 pounds of supplies, scientific investigations, hardware, and other cargo to the ISS for NASA and its international partners, JAXA’s (Japan Aerospace Exploration Agency’s) uncrewed HTV-X1 cargo spacecraft departed the ISS on Friday, March 6. The spacecraft arrived at the space station on Oct. 29, 2025, after launching Oct. 25 on an H3 rocket from Japan’s Tanegashima Space Center.
The HTV-X1 spacecraft will boost itself to a 500km circular orbit where it will remain for more than three months acting as a scientific platform for JAXA’s experiments.
After attaining this higher orbit, HTV-X1 will deploy Ten-Koh 2, a 6U cubesat constructed by Nihon University carrying a variety of amateur radio experiments. These will include:
- A linear transponder, developed by JAMSAT, that will operate two days each week (schedule to be announced). Transponder frequencies that have been coordinated with the International Amateur Radio Union (IARU) feature an uplink in the range 145.895-145.935 MHz with downlink 435.875-435.915 MHz.
- Digitalker with pre-loaded audio to be transmitted at 435.895 MHz.
- Transmission of pre-loaded digital images created in cooperation with students from the Faculty of Arts, also at 435.895 MHz.
- Demonstration of microwave band communication technology at 5.8 GHz in the microwave band.
- Tests of high-speed data transmission at 38.4 kbps in 4FSK.
Following the deorbit command, HTV-X1 will dispose of several thousand pounds of trash from the ISS during re-entry into Earth’s atmosphere, where it will burn up harmlessly. However, Ten-Koh 2 is expected to remain in orbit and active for approximately one year to 18 months.