October 29, 2025

— For the first time in five years, a Japanese spacecraft has arrived at the International Space Station.

JAXA (the Japan Aerospace Exploration Agency) on Wednesday (Oct. 29) oversaw the HTV-X1, its first upgraded cargo ship, as it was captured and berthed to the orbiting complex. Japanese astronaut Kimiya Yui and NASA astronaut Zena Cardman, members of the Expedition 73 crew, used the station's Canadarm2 robotic arm to grapple the solar-powered spacecraft at 11:58 a.m. EDT (1558 GMT or 12:58 a.m. Japan Standard Time on Oct. 30).

"HTV capture complete," said Yui. "This is a historic event in the Japanese space program. The spacecraft is so beautiful and shiny, representing our bright future."

NASA flight controllers at the Mission Control Center in Houston are set to control the arm and berth the HTV-X1 on the nadir port of the station's Harmony Node 2.

The HTV-X1 was launched atop an H3 rocket from the Tanegashima Space Center in Japan at 9:00 a.m. JST on Sunday (Oct. 26) [8:00 p.m. EDT on Oct. 25 or 0000 GMT on Oct. 26]. During its approach to the space station, the vehicle completed tests to demonstrate its performance and capability to maneuver.

HTV-X1 rendezvous and capture. Click to enlarge video in new pop-up window. (NASA)

'X' for advanced

Designed with an eye towards future missions beyond the ISS, the HTV-X differs from its preceding nine HTV (H-II Transfer Vehicle) craft in both appearance and capability. Although it is about 4 feet (1.2 meters) shorter than its predecessor, the HTV-X can carry approximately the same mass (about 13,200 pounds or 6,000 kilograms) into low Earth orbit.

The advanced vehicle offers increased power capabilities when not berthed (when attached to the station, the HTV-X draws electricity from the complex). The original HTV had solar cells mounted to its main body; the HTV-X has two solar paddles. That, together with a larger propellant tank enables HTV-X to support independent payloads in Earth orbit for up to 18 months after a half a year at the space station.

Upgrades could someday lead to a crewed version and, more in the near term, an autonomous docking capability.

"So, initial version is we need to capture it. That's going to be step by step," said Yui in an interview with collectSPACE prior to his launch. "And the next one, hopefully we're going to have a docking system. It might be on the third one."

"Eventually we are going to have a docking version of HTV-X. Then we can use it for the future exploration [missions] as well," he said.

Yui previously supported the arrival of HTV-5 when he was a member of the space station's Expedition 44 crew in August 2015.

Science, supplies and sake

Like the earlier HTV, HTV-X carries both pressurized and unpressurized cargo.

HTV-X1 is loaded with supplies for the Expedition 73 crew, including fresh food, oxygen and water. The vehicle also has on board replacement parts for JAXA's Kibo module, science and technology demonstration equipment and six CubeSats to be deployed from the space station.

On board but inside the unpressurised cargo module is JAXA's i-SEEP (IVA-resuppliable Small Exposed Experiment Platform), an adapter to make it easier to conduct science investigations without having to develop support hardware. i-SEEP can provide power, fluids and communications and easily be mounted on Kibo's external "porch."

There are also several commercial payloads on HTV-X1, including an attempt at sake fermentation through a partnership between Dassai and Mitsubishi Heavy Industries; an educational outreach project starring the stuffed toy mascot for the outdoor apparel brand CHUMS; plant seeds to be later cultivated and flowered on Earth for display at the World Horticultural Exhibition in 2027; toys and prints from online entertainers (VTubers); and Japan Airlines "passports" that will be stamped and photographed on the space station before being returned to their owners.

There are several payloads that will not be unpacked or moved over to the station, but instead will be tested for three months in Earth orbit after HTV-X1 departs. These payloads include a small satellite deployer to demonstrate releasing CubeSats at altitudes above the orbit of the ISS; a range finder (Mt.FUJI) to gauge the accuracy of telemetry readings with laser measurements; and a lightweight flat antenna (DELIGHT) and next-generation solar cell (SDX) that could support future space power generation systems.