On its maiden flight, HTV-X - launched on October 26, 2025 - has achieved another critical mission milestone just days later with its successful arrival at the ISS.

HTV-X is a Japanese cargo transfer vehicle designed to deliver essential goods such as food, water and clothing as well as experiments to astronauts aboard the International Space Station (ISS). It is capable of transporting large spare parts and technical equipment. After berthing with the ISS, the spacecraft remains attached for a certain period, during which it is loaded with garbage and waste. After departing from the ISS, several technical demonstrations will be conducted before re-entering the atmosphere. Upon re-entry into Earth's atmosphere, HTV-X burns up and thereby ensures the safe disposal of the waste it carries. The key advantage of HTV-X is an increased cargo capacity.

 
The Japan Aerospace Exploration Agency (JAXA) serves as the customer and operator of HTV-X. HTV-X consists of two modules: a Service Module (SM) that integrates all the functions required for the spacecraft to navigate in outer space and a Pressurized Module (PM) that is used to stow cargoes to be used in the ISS (experiment racks, experiment devices, potable water, foodstuffs and clothing). Mitsubishi Electric Corporation (MELCO) acts as the prime contractor, responsible for the development and manufacturing of the Service Module (SM). The German space company Jena-Optronik provides RVS3000 LiDAR sensors and ASTRO APS Star Trackers for HTV-X on behalf of MELCO.

 
“HTV-X is a crucial component of Japan's space program in the coming years. We are deeply honored to contribute to the mission's success with our sensors”, explains Matthias Pischeli from Jena-Optronik’s #teamspace. “We are truly thankful to MELCO for their trust in our sensors. For Jena-Optronik, it is an honor to have continuously supported the Japanese Cargo Resupply Missions with our LiDAR and Star Tracker technology for more than 20 years. Personally being involved since the very beginning of our collaboration, and also our whole team are incredibly proud of the achievements accomplished with MELCO and JAXA in the HTV-X program.”

 

LiDAR sensor RVS^© 3000 for HTV-X

The RVS 3000 configuration is used for the maiden flight of the HTV-X mission. This configuration has a long lasting, very successful heritage and consistently demonstrated outstanding performance on numerous rendezvous and docking missions with the International Space Station.

The two RVS 3000 units on the HTV-X cargo spacecraft ensure semi-automatic, safe, and precise guidance of the resupply vehicle toward the ISS. When a predefined “parking” position in very close proximity to the ISS is reached, the resupply vehicle is captured by the station's robotic arm.

 
The RVS 3000 LiDAR system, used for rendezvous and docking, measures the distance and relative motion between the spacecraft and the ISS as target. It does this by emitting laser pulses and measuring the time-of-flight of the reflected laser beam. This time-of-flight corresponds to the distance. By determining the direction of each returned laser pulse, the system calculates the relative 3D coordinates of each point.

 
Operating in autonomous guidance mode, the RVS 3000 uses known retro-reflectors on the ISS. The system features a compact, space-proven single-box design. As an active sensor, the LiDAR provides accurate 3D information even in darkness or shadow, independent of sunlight or target illumination - unlike cameras or passive sensors. 
 

The RVS 3000 is essential for the guidance, navigation, and control systems, enabling precise maneuvers to avoid collisions and ensures the reliable berthing of the resupply vehicle to the International Space Station (ISS).

Star Tracker ASTRO^© APS for HTV-X

Jena-Optronik supports the HTV-X mission with its state-of-the-art star tracker, the ASTRO APS. Two units are installed on the latest Japanese resupply vehicle. 

 
The ASTRO APS provides attitude information with exceptional accuracy of less than 1 arc second across the boresight. This supports precise navigation of the HTV-X transporter on its trajectory to the ISS. The working principle of the fully autonomous star tracker is to acquire the star patterns in the field of view and to determine based on this attitude information using in-house developed algorithms as well as an onboard star catalog. The system covers the entire celestial sphere and tolerates high rotational rates of the spacecraft of up to 5° per sec. 

Therefore, the ASTRO APS is an essential component of the Attitude and Orbit Control System (AOCS), ensuring safe and precise navigation to the berthing position of the International Space Station (ISS).

Japan's HTV-X1 cargo spacecraft is captured by the International Space Station's Canadarm2 robotic arm. (JAXA/Kimiya Yui)