# HTV-X by JAXA

Canonical page: https://technooptimist.io/spaceflight/htv-x
Frontier: [Spaceflight](https://technooptimist.io/spaceflight.md) · Field: Crew & cargo vehicles · Company: [JAXA](https://technooptimist.io/companies/jaxa.md)
Stage: Pilot (3 of 5: Research → Proto → Pilot → Deploy → Scaling)
Updated: last update 2026-03-11, facts checked 2026-10-11
Goal: Resupply the ISS at about half the cost of Japan's earlier HTV ship while carrying more, and turn each ship into a free-flying lab for testing new space hardware after it leaves the station.
Status: HTV-X1 flew in 2025-26; HTV-X2 launches no earlier than fall 2026 on an H3.
Next milestone: HTV-X2 launch to the ISS, target Q4 2026 (slipped 3 months; originally Q3 2026)

## Milestones

| Status | Milestone | Date | Slip |
| --- | --- | --- | --- |
| Done | HTV-X1 launches on an H3 from Tanegashima | 26 Oct 2025 |   |
| Done | HTV-X1 captured and berthed at the ISS | Oct 2025 |   |
| Done | HTV-X1 leaves the ISS after about four months | 6 Mar 2026 |   |
| Done | Deploys Nihon University's Ten-Koh2 satellite in free flight | 11 Mar 2026 |   |
| Done | HTV-X1 reenters after three months of tests | 26 May 2026 |   |
| Current | HTV-X2 launch to the ISS | Q4 2026 | +3 mo (originally Q3 2026) |
| Planned | HTV-X3 launch | 2027 |   |

## Upcoming events

- **Q4 2026**: HTV-X2 launch to the ISS (slipped 3 mo)
- **2027**: HTV-X3 launch

## Most important updates

- **11 Mar 2026**: HTV-X1 deploys Nihon University's Ten-Koh2 satellite, its first free-flight demonstration. Using its new H-SSOD deployer, HTV-X1 released the Ten-Koh2 satellite built by Nihon University. ([our story](https://technooptimist.io/stories/htv-x1-deploys-nihon-university-s-ten-koh2-satellite-its-first-free-83f7c8a6.md) · [original source](https://global.jaxa.jp/about/president/presslec/202604.html))
- **6 Mar 2026**: HTV-X1 leaves the ISS after four months and begins three months of free-flying tests. The station's Canadarm2 arm released Japan's first HTV-X cargo ship on March 6 (March 7 in Japan), ending its supply mission after about four months. ([our story](https://technooptimist.io/stories/htv-x1-leaves-the-iss-after-four-months-and-begins-three-months-of-free-cb2798a7.md) · [original source](https://global.jaxa.jp/press/2026/02/20260219-1_e.html))

## Current obstacles

- **Tied to the H3 rocket**: HTV-X can only fly on Japan's H3, so its schedule follows the rocket's; HTV-X2 has already slipped from summer to fall 2026 or later.
- **Automated docking demo may move**: HTV-X2 was meant to test docking on its own instead of being caught by the arm; JAXA said in 2025 the demo may move to a later flight.

## Physics limits

- **Single-use by design**: Cargo ships are built to burn up with the station's rubbish. Bringing anything back needs a heat shield and recovery system, which cost mass that would otherwise be cargo.
- **Berthing needs a robot arm and a crew**: A berthed ship must hover close enough for the arm to grab it, which needs a crewed station and its arm. Docking on its own needs extra sensors and a docking port.

## How it works

### Two-part ship: A cargo can on an engine room

A pressurized module reused from the old HTV holds crew supplies; a new service module carries the thrusters, solar panels, batteries and radios.

### Outside cargo: Big items ride on top

Unpressurized cargo sits on top of the service module, so its size is set by the rocket's fairing rather than an internal rack.

### Berthing: Caught by the station's arm

HTV-X flies to a point just below the ISS and holds still; astronauts grab it with the Canadarm2 robot arm and bolt it to a port.

### Test platform: A lab after the delivery

After leaving, it can fly for up to 18 months; HTV-X1 deployed a satellite and tested a laser reflector, a light antenna and solar cells.

## Spec sheet

| Spec | HTV-X | HTV (Kounotori) | Provenance |
| --- | --- | --- | --- |
| Launch mass | 16,000 kg |   | reported |
| Pressurized cargo | 4,070 kg |   | reported |
| Unpressurized cargo | 1,750 kg |   | reported |
| Pressurized volume | 39.6 m³ |   | reported |
| Length × diameter | 8 m × 4.4 m |   | reported |
| Solar power | 1 kW | 200 W (HTV) | reported |
| Time berthed at ISS | Up to 6 months |   | reported |
| Free flight after departure | Up to 1.5 years |   | reported |

Provenance: reported = stated by the company; estimated = our estimate; sample = a sample figure.

## About JAXA

Japan's national space agency, responsible for launch vehicles, exploration spacecraft and ISS experiments. Leads Japan's space science and deep-space missions.

- JAXA operates Japan's H3 heavy-lift launch vehicle and leads scientific deep-space missions.
- The Martian Moons eXploration (MMX) spacecraft launches on H3 F10 on October 20, 2026, to return samples from Phobos.
- MMX is a collaborative mission with NASA, ESA, CNES and DLR.

- Founded: 2003
- Headquarters: JP
- Status: government
- Website: https://global.jaxa.jp
- People: Hiroshi Yamakawa (President)
- Partners, customers, investors: NASA (partner); European Space Agency (partner); French Space Agency (partner); German Aerospace Center (partner)

Company page: https://technooptimist.io/companies/jaxa.md

## Related programs

More from JAXA:

- [Martian Moons eXploration](https://technooptimist.io/spaceflight/mmx.md) (Deploy)

Everything in Spaceflight: https://technooptimist.io/spaceflight.md

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