HTV-X1

HTV-X1

Mission type	ISS resupply
Operator	JAXA
Mission duration	~30 days (planned) [1]
Spacecraft properties
Spacecraft type	HTV-X
Manufacturer	Mitsubishi Heavy Industries
Launch mass	16,000 kg (35,000 lb) [2]
Dimensions	8.0 m × 4.4 m (26.2 ft × 14.4 ft)
Start of mission
Launch date	NET 21 October 2025, 01:58  UTC (10:58  JST) [3]
Rocket	H3-24W, Flight 7 [2]
Launch site	Tanegashima, LA-Y2
Contractor	Mitsubishi Heavy Industries
Orbital parameters
Reference system	Geocentric orbit
Regime	Low Earth orbit
Inclination	51.6°
Berthing at ISS
Berthing port	Harmony or Unity nadir
Cargo
Mass	5,819 kg (12,829 lb) [1]
Pressurised	4,069 kg (8,971 lb) [1]
Unpressurised	1,750 kg (3,860 lb) [1]
HTV (Kotonotori) ←  Kounotori 9 HTV-X2  → HTV-X HTV-X2  →

HTV-X1 is the first flight of the HTV-X series, serving as a technical demonstration mission of the new uncrewed expendable cargo spacecraft. It is scheduled to launch on 21 October 2025. ^{[4] [5]}

Cargo

Pressurised cargo

HTV-X1 will deliver the following pressurised cargo to the International Space Station (ISS): ^[6]

• Crew supplies
• DRCS (Demonstration of Removing Carbon Dioxide System)
• NORS (Nitrogen/Oxygen Recharge System) tank
• RST (Water Resupply Tank)

Unpressurised cargo

• i-SEEP (IVA-replaceable Small Exposed Experiment Platform)

Additional payloads

In addition to its primary cargo mission, HTV-X1 carries several technology demonstration payloads: ^[2]

• DELIGHT, a demonstration of a lightweight expandable flat antenna
• Mt.FUJI, a technology demonstration for satellite laser ranging
• H-SSOD, a small satellite deployer that will release the CubeSat Ten-Koh 2 following departure from the ISS

References

1. G. D. Krebs. "HTV-X1, 2, 3 (Kotonotori 1, 2, 3)". Gunter's Space Page. Retrieved 25 August 2025.
2. 新型宇宙ステーション補給機（HTV‐X）の開発状況について [Development status of the new space station resupply vehicle (HTV-X)](PDF) (in Japanese). MEXT. 9 February 2021. Retrieved 4 March 2021.
3. "HTV-X1". Next Spaceflight. Retrieved 26 October 2024.
4. "Launch Schedule of New unmanned cargo transfer spacecraft（HTV-X1）aboard the 7th H3 Launch Vehicle (H3 F7)". JAXA. 22 August 2025. Retrieved 23 August 2025.
5. "Japan to launch new ISS resupply vehicle in October". The Japan Times. 23 August 2025. Retrieved 25 August 2025.
6. 新型宇宙ステーション補給機（HTV-X）1号機の開発状況 [Development status of the first HTV-X (HTV-X) space station resupply vehicle](PDF) (in Japanese). JAXA. 2 June 2025. Retrieved 3 June 2025.