HTV-X1 is the first flight of theHTV-X series, serving as a technical demonstration mission of the newuncrewed expendablecargo spacecraft. It launched on 26 October 2025.[2]
As the maiden flight, HTV-X1 is flown as a technical demonstration and was thus not loaded to maximum capacity, with a deficit of approximately 1,500 kilograms (3,300 lb) deducted mainly from unpressurised cargo.[a] Attaining the full design capacity of the HTV-X, 4,069 kg (8,971 lb) pressurised and 1,750 kg (3,860 lb) unpressurised,[4] requires use of the H3 rocket's optional[c]Autonomous Flight Safety System, which enables the flight to be aborted autonomously if anomalies are detected while the rocket is out of range of ground control centers. This system was first tested, but not fully operational during HTV-X1's launch on H3 Flight 7.[b][6][d]
HTV-X1 is scheduled to remain berthed to the ISS for up to six months, during which cargo will be transferred to the ISS and waste loaded onto the HTV-X.[1]
The Japanese licensee for outdoor apparel brand CHUMS[ja] will film advertising and educational videos involving its mascot character in stuffed toy form
Rice seeds fromKazo, Saitama are being sent to the ISS and will be subsequently recovered for cultivation on Earth in a local agriculture and education initiative byDigitalBlast
Japan Airlines is sending "passports" of customers to be stamped and photographed on board the ISS before being returned to their owners
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Atechnology demonstration will showcase the deployment and operation of small, automatic, distributed sensors intended for monitoringenvironmental quality on board future commercial space stations
Apart from its primary cargo mission, the HTV-X is also capable of serving as an orbital platform for conducting experiments and technology demonstrations for up to one and a half years following departure from the ISS. The technology demonstration mission phase for HTV-X1 is planned to last three months, and involves the following payloads:[1]
H-SSOD, a small satellite deployer that will release theCubeSatTen-Koh 2 at an altitude of approximately 500 km. This will demonstrate HTV-X's capability to deploy microsatellites from a higher orbit than the ISS, which offers a longer operational lifetime (with respect toorbital decay) and opens up new potential applications for deployed satellites.
Mt.FUJI, a technology demonstration forsatellite laser ranging (SLR). Apart from measuring distance from the ground to the HTV-X, this will be the time that the accuracy ofspacecraft attitude determination using SLR is evaluated against actual spacecraft telemetry.
Technologies related to construction of large space structures for future space solar power generation systems and other applications:
DELIGHT, a lightweight flat antenna mounted to the deployable structure
SDX, a next-generation solar cell technology demonstration
The HTV-X project was formally initiated in 2017, originally intending to launch the first flight in JFY2021,[8] though eventually it was delayed to 2025 due to the delay of H3 launch vehicle development. Manufacturing of a proto-flight model began in 2018.[9] The Pressurized Module (PM) for HTV-X1 was assembled byMitsubishi Heavy Industries inAichi Prefecture and shipped to theTanegashima Space Center (TNSC) in August 2022.[1][10] The Service Module (SM) was assembled byMitsubishi Electric inKanagawa Prefecture and delivered to TNSC in January 2025.[1][10]
At TNSC, the PM and SM were integrated, and a full system checkout was completed in May 2025.[1] The modules were then separated for cargo and propellant loading beginning in August 2025.[1] The PM and SM were reintegrated and encapsulated within the payload fairing on 9 October, and mated to the H3 launch vehicle on 14 October.[5] Late-access cargo, including perishable food, was loaded on 19 October.[11]
HTV-X1 was initially scheduled for launch on 21 October 2025.[12] The launch was postponed due to unfavorable weather conditions.[13]
HTV-X1 was successfully launched on 26 October 2025 at 00:00:15 UTC (09:00:15 JST) aboard Flight 7[b] of the H3 launch vehicle from Launch Area 2 of theYoshinobu Launch Complex at TNSC.[14] This mission marked the first H3 flight to use four solid rocket boosters and the first with a wide payload fairing.[15]
On 29 October 2025, JAXA astronautKimiya Yui, assisted byZena Cardman, captured the spacecraft using the roboticCanadarm2 at 15:58 UTC.Akihiko Hoshide served asCAPCOM from NASA’sMission Control Center at theJohnson Space Center in Houston, Texas.[16] Ground teams at NASA and JAXA'sTsukuba Space Center completed berthing to the nadir (Earth-facing) port of theHarmony module at 19:43 UTC. Power transfer from the ISS to HTV-X1 was confirmed at 11:10 UTC on 30 October.[17][18] During the approach, the spacecraft conducted a commanded retreat maneuver as part of a proximity operations demonstration.[19]
The hatch of the Pressurized Module was opened at approximately 12:37 UTC on 30 October.[20]
On 4 November, theCanadarm2 removed the i-SEEP3B payload from the unpressurized cargo deck and transferred it to the roboticJEMRMS arm for installation inside theKibō module’s airlock.[7]
Departure from the ISS and post-berthing operations
HTV-X1 is planned to leave the ISS on 6 March 2026.[21]
Following its departure from the ISS, HTV-X1 is scheduled to conduct a series of technology demonstration missions lasting approximately three months.[1]
^abc"H3ロケット7号機による新型宇宙ステーション補給機1号機（HTV-X1）の 打上げ結果" [Launch result of new unmanned cargo transfer spacecraft HTV-X1 aboard H3 rocket flight 7] (Press release) (in Japanese). JAXA. 26 October 2025.
^Sasaki, Hiroshi; Ito, Norimasa (9 February 2021).新型宇宙ステーション補給機（HTV‐X）の開発状況について(PDF) (in Japanese). Ministry of Education, Culture, Sports, Science and Technology. Retrieved7 November 2025.
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