AN END OF AN ERA: Japanese H-IIA rocket launches for the final time, carrying the GOSAT-GW satellite
H-IIA launching for the 50th and final time (Credit: JAXA)
After a historic 25 years since its first launch, the H-IIA rocket by Mitsubishi Heavy Industries (MHI) and the Japan Aerospace Exploration Agency (JAXA) launched for its 50th and final flight from the Yoshinobu Launch Complex (LP-1) at the Tanegashima Space Center in Japan. Liftoff occurred on June 29, 2025, at 1:33 AM Japan Standard Time (JST) (4:33 PM UTC; June 28). The rocket was carrying the GOSAT-GW satellite by JAXA, which is a next-generation satellite to be used to monitor greenhouse gases like carbon dioxide in the Earth’s atmosphere.
With its near-perfect track record of 49 out of 50 successful missions, this rocket provided Japan and its other customers access to space for 25 years. One may ask, how did this final launch go? What are the instruments and purposes inside this satellite? What is the next rocket coming after this?
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Launch to Deployment Recap
After igniting its core stage engine seconds before T-0, the two solid rocket boosters on the rocket ignited. The rocket lifted off from the pad at 1:33 a.m. Japan Standard Time (JST), marking the launch of the 50th and final flight of the H-IIA rocket, carrying the GOSAT-GW satellite onboard. The vehicle passed Maximum Aerodynamic Pressure (Max-Q) soon after.
Approximately 3 minutes after liftoff, the two solid rocket boosters had all their fuel burned off, initiating booster separation soon after.
Based on the mission control audio, the fairing separation was also confirmed around 4 minutes and 20 seconds after liftoff.
At six minutes and 38 seconds into the mission, the main engine cutoff (MECO) occurred, followed by stage separation eight seconds later. The second stage then ignited after this maneuver.
The second stage burned its engines for around eight minutes and 15 seconds, performing a second stage engine cutoff (SECO) after that estimated duration.
The GOSAT-GW satellite was then deployed around 16 minutes and one second, 51 seconds after second stage engine cutoff (SECO).
Completion of Critical Operations Phase
After the deployment of the spacecraft, JAXA has confirmed the success of the critical operations phase, making the satellite conduct three vital deployments for it to operate normally. The operations that were conducted on separate days after deployment were:
1. Deployment of the solar array paddles
“The Japan Aerospace Exploration Agency (JAXA) confirmed that the solar array paddles deployment was successfully performed by receiving telemetry from the Global Observing SATellite for Greenhouse gases and Water cycle “IBUKI GW” (GOSAT-GW).
The following are images of “IBUKI GW” (GOSAT-GW) solar array paddles received at the Santiago Station in Chile on June 29, 2025 at 2:25(JST).”
Credit: JAXA
2. Antenna deployment
“The Japan Aerospace Exploration Agency (JAXA) confirmed that the AMSR3*1 antenna deployment*2 was successfully performed by receiving telemetry from the Global Observing SATellite for Greenhouse gases and Water cycle “IBUKI GW” (GOSAT-GW). The following is actual photo of the AMSR3 antenna received at the Kiruna Station in Sweden on June 30 2025 at 14:57 (JST).”
Credit: JAXA
3. Initial run-up phase
“The Japan Aerospace Exploration Agency (JAXA) confirmed that the AMSR3 initial run-up*1 was successfully performed by receiving telemetry from the Global Observing SATellite for Greenhouse gases and Water cycle “IBUKI GW” (GOSAT-GW).
The following are images of the initial run-up received at the Kiruna Station in Sweden on June 30 2025 at 19:45 (JST).”
Credit: JAXA
About GOSAT-GW
The GOSAT-GW satellite (Credit: JAXA and NASASpaceflight)
The Global Observing Satellite for Greenhouse Gases and Water Cycle (GOSAT-GW) satellite by JAXA is a next-generation Earth-observation satellite by Japan to be used in monitoring the global water cycle and greenhouse gases like carbon dioxide in the Earth’s atmosphere.
It is also known as Ibuki GW and was formerly called GOSAT 3.
This mission is jointly developed by the Japan Aerospace Exploration Agency (JAXA), the Ministry of the Environment, and the National Institute for Environmental Studies (NIES).
The satellite will be a follow-up of its predecessors, which are the GOSAT 2 (Ibuki 2) and GCOM-W (Shizuku) missions.
What will follow the HII-A rocket?
Artwork placed on the HII-A rocket for its 50th & last flight (Credit: JAXA)
As the HII-A finally said its goodbye, JAXA and MHI still have remaining new rockets in place to fill in the role of the HII-A.
One of these Japanese rockets is the H-3, which has already flown 5 times, 4 of which are consecutive successful flights until this present. This launcher is one with a matching capacity to the H-IIA, while being cheaper in terms of cost.
Another Japanese rocket is the Epsilon rocket, which is a smaller, solid-fueled vehicle for lighter payloads. While not comparable to the huge payload capacity of the H-3 rocket, it will be part of the remaining options that Japan has for its access to space.
This is KYNNMASTER 123 for TWS: The Weekly Spaceman, see you in the next one! 😁
