HTV-X1

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]

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 →

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