Japan Retires H2A After 50 Launches, Sending Climate Satellite Into Orbit on Final Flight

A final flight closes 24 years of Japanese space history

Japan's H2A rocket completed its 50th and final mission in the early hours of June 29, 2025, carrying a satellite designed to monitor greenhouse gases and the global water cycle into orbit. The successful launch from the Tanegashima Space Center in Kagoshima Prefecture ended a career spanning nearly a quarter of a century and completed the rocket's record of 49 successful missions from 50 attempts.

The final payload, GOSAT-GW, also known as Ibuki GW, connects the rocket's retirement with a continuing task: gathering information about global warming, the movement of water around the planet and conditions at the ocean surface. Japan now turns to the H3 rocket as its main launch vehicle, seeking lower costs and a stronger position in the international launch market.

More than 1,300 spectators gathered at Tanegashima to watch the departure. Cheers accompanied the engines lighting up the sky before dawn, bringing a public celebration to a moment that carried particular weight for the engineers and officials responsible for the program.

Keiji Suzuki, the Mitsubishi Heavy Industries official in charge of the final launch, described his relief and the importance of reaching the program's reliability goal:

I was more nervous than ever about the launch and feel like I'm still dreaming. We achieved our long-cherished goal of a 98 percent success rate.

That figure captures the H2A's central achievement. Since its debut in 2001, the rocket became the backbone of Japan's access to space, carrying missions for weather forecasting, navigation, national security and scientific exploration. Its retirement closes a dependable chapter while placing responsibility for future launches on its successor.

How H2A built its reliability record

Mitsubishi Heavy Industries (MHI) developed the H2A in partnership with the Japan Aerospace Exploration Agency (JAXA). Across 24 years, the rocket achieved a success rate of 98 percent, placing it among the world's most reliable launch vehicles.

The program's only failed mission came in 2003, on its sixth launch. A damaged jet nozzle and a booster separation problem led to the destruction of the rocket. The failure prompted an investigation and redesign lasting about a year, followed by changes intended to prevent the problem from recurring.

H2A then completed 44 consecutive successful launches. Together with the five successful flights before the accident, that run brought the final total to 49 successes in 50 attempts. The record reflects both the early setback and the sustained performance that followed the engineering changes.

The main dates show how the rocket's career and the development of its replacement overlapped:

• 2001: H2A made its debut and began its role as Japan's principal launch vehicle.
• 2003: The sixth H2A mission failed, leading to an investigation and redesign.
• March 2023: The H3 rocket's first flight failed when its second stage engine did not ignite.
• June 29, 2025: H2A completed its 50th and final launch, successfully deploying GOSAT-GW.

A rocket built for different destinations

H2A used two stages powered by liquid fuel, with solid fuel boosters added when needed for heavier payloads. That arrangement gave the rocket the flexibility to carry different spacecraft and support missions with very different destinations.

The rocket could send satellites into geostationary and sun-synchronous orbits, as well as onto trajectories toward the Moon. Its range of missions allowed Japan to use one launch system for services close to everyday life and for exploration far beyond Earth.

Weather forecasting, satellite navigation and deep space science all benefited from that flexibility. The same program that supported practical services across Japan and the wider region also helped scientists investigate an asteroid and reach the lunar surface.

The missions that shaped H2A's legacy

Himawari meteorological satellites were among H2A's important payloads. They support weather forecasting across the Asia-Pacific region, giving the rocket a role in services used well beyond Japan. The program also contributed to disaster management through the spacecraft it placed in orbit.

Michibiki satellites, part of Japan's Quasi-Zenith Satellite System, supported more accurate GPS positioning in Japan and neighboring countries. Alongside weather observation, navigation was one of the practical tasks made possible by the rocket's ability to launch satellites into different orbits.

Hayabusa2 extended that record into planetary science. The asteroid mission returned samples from Ryugu to Earth, attracting global attention and giving researchers material that could help them understand the origins of the solar system.

The SLIM lunar lander was another major payload. Its mission made Japan the fifth nation to achieve a soft landing on the Moon, adding a lunar milestone to a launch history already spanning weather, navigation and asteroid exploration.

H2A also carried reconnaissance satellites for national security. The related H2B variant supported International Space Station resupply missions using HTV cargo vehicles. Across these activities, Japan's launch capabilities served scientific, strategic and international purposes, while the H2A's reliability strengthened its reputation as a spacefaring nation and supported partnerships with agencies and organizations worldwide.

What the last satellite will measure

GOSAT-GW, the Global Observing Satellite for Greenhouse Gases and Water Cycle, gives the final H2A mission a focus on Earth's changing environment. The satellite combines observations of the atmosphere with measurements connected to water and the oceans.

Its two main instruments have different jobs. The Advanced Microwave Radiometer (AMSR) monitors the water cycle and sea surface temperatures. The Greenhouse Gases Observation Sensor (TANSO) tracks atmospheric carbon dioxide, methane and other greenhouse gases.

Together, those instruments are intended to provide detailed information about greenhouse gas concentrations and water cycle conditions. The satellite's mission brings those measurements into one program, supporting research into global warming as well as international efforts to monitor and limit climate change.

From observations in orbit to climate information

GOSAT-GW can observe a strip approximately 900 kilometers wide at a time. That broad coverage supports comprehensive, seamless surveys of the planet, allowing scientists and policymakers to study environmental conditions over a much wider area than a single local observation could cover.

The satellite is designed to provide information at high resolution and close to the time observations are made. Those features matter for a mission examining both greenhouse gas concentrations and the movement of water, where the goal is to build a detailed picture of conditions across the globe.

Takashi Hamazaki, JAXA's GOSAT project manager, described the mission's role in climate research:

GOSAT-GW will play an important role in understanding global warming.

The plan is to make its data available to users worldwide within a year, including agencies such as the U.S. National Oceanic and Atmospheric Administration (NOAA). The timetable gives the final launch a purpose extending well beyond the retirement ceremony: observations intended to inform climate policy and scientific research for years to come.

Why reliability was not enough commercially

H2A's technical record did not translate into a large share of the commercial satellite launch market. Its estimated cost of around 10 billion yen, roughly $90 million, per flight limited its appeal to international customers.

Competition added pressure. SpaceX's Falcon 9 helped drive launch prices down, making cost a difficult part of the H2A's business case even as its reliability improved. A successful record was valuable, but customers also had to weigh the price of getting their satellites into space.

Japan consequently used H2A primarily for government, scientific and national security missions. Commercial launches remained a small part of its work, with only a handful undertaken for customers such as Inmarsat and Telesat.

The contrast between dependable performance and limited commercial reach helps explain the move to H3. Japan wants to retain reliable access to space while making its launch service less expensive and more attractive to a broader range of customers. The successor's goals therefore reach beyond replacing an aging rocket: they include changing the cost and capacity of Japan's launch operations.

H3 takes over with a lower cost target

JAXA and MHI jointly developed the H3 as Japan's next main launch vehicle. It is intended to address the H2A's commercial limitations through a combination of lower launch costs, greater payload capacity and several configurations suited to different mission requirements.

The cost target is roughly half that of H2A. Against the predecessor's estimated 10 billion yen per flight, that target represents a substantial reduction in the expense of reaching space. H3 is also designed to carry larger and heavier satellites, giving Japan more capacity as well as a lower price goal.

Different configurations allow the rocket to be adapted to different missions. That flexibility is part of the effort to serve a wider range of launch needs, rather than relying on a single arrangement for every customer and payload.

H3's development has included a serious setback. Its maiden flight in March 2023 ended in failure after the second stage engine failed to ignite, resulting in the loss of both the rocket and its payload. Subsequent launches have succeeded, preparing the vehicle to take over as Japan's mainstay launcher.

Hiroshi Yamakawa, president of JAXA, expressed the emotion surrounding the transition from the rocket the agency helped develop:

It is a deeply emotional moment for all of us at JAXA as a developer.

The transfer of responsibility brings two goals together. Japan needs stable access to space for government and scientific missions, while also seeking a commercially competitive transport service. H3's continued operational success will shape its ability to meet both needs.

A wider strategy for Japan's access to space

Japan is also developing the smaller Epsilon rocket for compact satellites. Alongside H3, that program is intended to help the country serve a wider range of customers and mission sizes.

The government regards an independent, dependable launch capability as essential to technological sovereignty, economic growth and international collaboration. In practical terms, Japan wants the ability to send its own important spacecraft into space while continuing to work with international partners.

National security is part of that calculation, as shown by H2A's reconnaissance satellite missions. Scientific discovery is another, reflected in Hayabusa2, SLIM and the climate satellite carried on the final flight. Commercial opportunity adds a further goal as the global space economy expands rapidly.

Japan hopes to secure a larger share of that commercial market without giving up the scientific and strategic roles its launch program already serves. H3 and Epsilon are intended to address different parts of that ambition, with H3 assuming the central role left by H2A.

A farewell tied to work still to come

The response to H2A's final launch combined nostalgia with anticipation. For engineers, scientists and members of the public, the retirement marked the end of an era associated with technical achievement and national pride. For those gathered at Tanegashima, the departure was also a visible reminder of how much of Japan's space activity had depended on one rocket program.

H2A leaves behind a record that joins everyday services with exploration: weather forecasting across the Asia-Pacific region, improved navigation, security missions, asteroid samples and a successful lunar landing. Its last payload adds a continuing effort to understand global warming and the planet's water cycle.

Japan's next chapter now depends on H3 delivering the reliability, lower costs and flexibility it was designed to provide. As GOSAT-GW begins its mission, the immediate results of H2A's final flight will be measured in environmental observations, while the longer transition will be measured through the performance of the rocket that replaces it.

Key Points

• H2A completed its 50th and final launch on June 29, 2025, from Tanegashima Space Center in Kagoshima Prefecture.
• The rocket retired after 24 years with 49 successful launches from 50 attempts, a success rate of 98 percent.
• Its only failure came in 2003. Engineering changes were followed by 44 consecutive successful missions.
• The final payload, GOSAT-GW, will monitor greenhouse gases, the water cycle and sea surface temperatures, with data intended for worldwide users within a year.
• Launch costs of around 10 billion yen, roughly $90 million, limited H2A's commercial appeal despite its reliability.
• H3 is taking over with targets including roughly half the launch cost, greater payload capacity and flexible configurations.
• Japan is also developing Epsilon for compact satellites as it pursues scientific, national security and commercial goals.