GOSAT-GW ("IBUKI GW") Successful Launch and Completion of Critical Operations Phase

Global Observing SATellite for Greenhouse gases and Water cycle (GOSAT-GW, "IBUKI GW")^*1 developed jointly by the National Institute for Environmental Studies (NIES), the Ministry of the Environment (MOE), and the Japan Aerospace Exploration Agency (JAXA) was successfully launched on the H-IIA Launch Vehicle No. 50 (H-IIA F50) by Mitsubishi Heavy Industries, Ltd. on June 29, 2025 from the JAXA Tanegashima Space Center. The GOSAT-GW was safely separated from the launch vehicle. JAXA received telemetry data confirming that the deployment of the solar array paddles^*2 and a series of operations for mission payloads (the antenna deployment and the initial run-up^*3 of AMSR3^*4, and release of the pointing mirror lock for TANSO-3^*5), have been completed, and that the satellite is in stable condition to remain in its proper orbit.

With this confirmation, the critical operations^*6 phase was completed.

GOSAT-GW will move on to the initial functional verification operations phase^*7, to verify the functions of the onboard instruments over a period of approximately three months.

We would like to express our deepest gratitude to all parties concerned for their support and cooperation in the process of GOSAT-GW development.

*1: Global Observing SATellite for Greenhouse gases and Water cycle (GOSAT-GW, "IBUKI GW")
GOSAT-GW carries two mission instruments: Advanced Microwave Scanning Radiometer 3 (AMSR3) and Total Anthropogenic and Natural emissions mapping SpectrOmeter-3 (TANSO-3).

*2: The deployment of the solar array paddles
The solar array paddles are folded compactly during launch and unfolded in orbit.

*3: The initial run-up
The process to run AMSR3's rotating drive at a slow speed after releasing its antenna and test if the rotation speed reaches the targeted value.

*4: AMSR3
AMSR3 is a sensor designed to measure weak microwaves emitted from the land surfaces and the atmosphere, developed by Ministry of Education, Culture, Sports, Science and Technology (MEXT) and JAXA.

*5: TANSO-3
TANSO-3 is a sensor designed to observe global greenhouse gases over a wide area and with high accuracy, developed by MOE, NIES, and JAXA.

*6: Critical operations phase
The phase after the satellite separation from the launch vehicle, to deploy the solar array paddles and the antenna of AMSR3, to release the launch locks of mission payloads (AMSR3 and TANSO-3), and to transfer the satellite to an operational state.

*7: Initial functional verification operations phase
The period to verify the functions of the satellite system and its onboard instruments including the mission payloads (AMSR3 and TANSO-3).

Reference:
NIES GOSAT-GW Project website:https://gosat-gw.nies.go.jp/en/index.html
MOE GOSAT Series website (in Japanese):https://www.env.go.jp/earth/ondanka/gosat.html　(redirects to external site)
JAXA GOSAT-GW Project website:https://www.satnavi.jaxa.jp/files/project/gosat-gw/en/　(redirects to external site)
Mitsubishi Heavy Industries, Ltd.:https://www.mhi.com/news　(redirects to external site)

Related press release:
April 25, 2025
Launch of the Global Observing SATellite for Greenhouse gases and Water cycle (GOSAT-GW) (Japanese Only)
https://www.nies.go.jp/whatsnew/2025/20250425/20250425-2.html

【Expert Contact】
Satellite Observation Center,
National Institute for Environmental Studies
　Tsuneo Matsunaga, Director
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Planning Division, Public Relations Office
National Institute for Environmental Studies
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