Japans GOSAT-GW to launch aboard final H-IIA rocket

Date:
Sat, 28 Jun 2025 15:02:28 +0000

Description:
The final flight of Japans H-IIA rocket will carry the GOSAT-GW environmental research satellite to The post Japans GOSAT-GW to launch aboard final H-IIA rocket appeared first on NASASpaceFlight.com .

FULL STORY ======================================================================The final flight of Japans H-IIA rocket will carry the GOSAT-GW environmental research satellite to orbit on Saturday, ending a career that has spanned 24 years and 50 missions. Liftoff from the Tanegashima Space Center is scheduled for a 19-minute window opening at 16:33 UTC (1:33 AM local time on Sunday).



The Global Observing Satellite for Greenhouse Gases and Water Cycle
(GOSAT-GW) is the third mission in the GOSAT series operated by the Japan Aerospace Exploration Agency (JAXA) . Previously, GOSAT stood for Greenhouse Gases Observing Satellite; the subtle change to the name for GOSAT-GW indicates the new satellites broader role that will see it also serve as a successor to the Global Change Observation Mission Water (GCOM-W), or Shizuku, satellite.

Japanese satellites typically have two names: a descriptive name such as
GOSAT or GCOM-W, and a more abstract or poetic name like Shizuku or Ibuki which is given to it once it reaches orbit. Following this tradition,
GOSAT-GW is expected to become the third satellite to be named Ibuki a name that means breath or puff. This was also the name given to the two previous GOSAT spacecraft that were launched in January 2009 and October 2018.

The 2,600 kg GOSAT-GW spacecraft carries two instruments: the Advanced Microwave Scanning Radiometer 3 (AMSR-3) and the Total Anthropogenic and Natural Emissions Mapping Spectrometer 3 (TANSO-3). It is expected to operate for at least seven years in a Sun-synchronous orbit 666 km above the Earth.



AMSR-3 is a microwave radiometer operating across eight spectral frequencies in 21 channels. It is capable of all-weather observation of microwave emissions from sources on the Earths surface or in the atmosphere. By
studying the spectra of these emissions, a number of data points related to water content can be extrapolated. This allows AMSR to build a picture of Earths water cycle by monitoring soil moisture levels, snow depths, sea ice, sea surface temperatures, and winds, water in clouds and precipitation, and water vapor in the atmosphere. See Also H-IIA F-50 Updates Japanese Section NSF Store Click here to Join L2

AMSR-3 follows on from the AMSR-2 instrument flown aboard Shizuku , which was launched in 2012. This was itself a successor to two first-generation AMSR payloads which were flown aboard the ADEOS II ( Midori 2) and Aqua
satellites, both of which launched in 2002. ADEOS II was lost early in its mission, but the instrument aboard Aqua was operated until late 2015 and AMSR-2 remains in service. Once AMSR-3 is operational it will ensure that
data collection continues uninterrupted as AMSR-2 ages and eventually reaches the end of its operational life.

TANSO-3 is the successor to similar instruments flown aboard the two previous GOSAT spacecraft. It will use diffraction grating spectrometry to measure concentrations of three greenhouse gases in the atmosphere: carbon dioxide, methane, and nitrogen dioxide. TANSO-3 has two observation modes: in its wide-area mode it can monitor a 911-km-wide swath with a resolution of 10 km; in precise observation mode its resolution increases to between one and three kilometers across a 90 km swath.

With TANSO-3, GOSAT-GW will supplement and eventually replace the two earlier satellites in monitoring global monthly average carbon dioxide levels, large sources of atmospheric greenhouse gases, and tracking anthropogenic (human-caused) emissions by country. The GOSAT-GW satellite prior to launch (Credit: JAXA)

GOSAT-GW will launch aboard the 50th and final flight of the H-IIA rocket, with the mission designated H-IIA F-50. First launched in 2001, the H-IIA has been one of Japans most successful rockets, delivering a wide array of commercial, scientific, and military spacecraft into orbit.

H-IIA evolved from the earlier H-II, which launched seven times between 1994 and 1999: six in its original form plus a seventh in a modified H-IIS configuration. H-II was Japans first fully-indigenous liquid-fueled launch vehicle, following on from the earlier N-I, N-II, and H-I, which combined Japanese-developed components with license-built hardware derived from the U.S. Thor and Delta vehicles. H-II was developed by the National Aerospace Development Agency (NASDA), a predecessor of JAXA which merged with the Institute of Space and Astronautical Science (ISAS) and the National
Aerospace Laboratory in 2003 to form Japans present-day space agency.

Early in H-IIs career, it became evident that the rocket cost too much per launch to compete with foreign commercial vehicles, so the H-IIA was
conceived as a lower-cost vehicle offering several configurations to tailor
it to different payloads. This new rocket first flew on Aug. 29, 2001, with another development launch on Feb. 4, 2002, clearing the way for its first operational flight that September. As with H-II, the project was led by
NASDA, with the rockets constructed and operated by Mitsubishi Heavy Industries (MHI) . H-IIAs predecessor, H-II, at the launch pad in February 1998 (Credit: JAXA)

The end of the original H-II was hastened by two launch failures. On its
sixth flight, the second stage engine burned through, causing a premature shutdown that left it in a lower-than-planned orbit. On the next launch, the only flight of the upgraded H-IIS, a turbopump malfunction caused a first stage engine failure about four minutes into the flight leaving the rocket unable to reach orbit.

During its time in service, H-IIA has flown in four different configurations, all differing in the types and numbers of solid rocket boosters used to augment the first stage during the early phases of flight. Further configurations with liquid-fueled boosters and enlarged upper stages were
also proposed or studied but none of these were developed.

Both the first and second stages of the rocket use cryogenic propellants: liquid hydrogen oxidized by liquid oxygen. The first stage is powered by a single LE-7A engine, while the second uses an LE-5B. At least two SRB-A solid rocket boosters upgraded to SRB-A3s from 2009 onwards provide additional propulsion at liftoff. H-IIA F-4 lifts off in 2002. The H-IIA 2024 configuration used SRB-A and Castor solid rocket motors. (Credit: JAXA)

For the GOSAT-GW launch, H-IIA is flying in its 202 configuration. With just
a pair of SRB-A3 motors, this is the lightest configuration and also the most frequently flown. Of 50 H-IIA missions, 35 have used the H-IIA 202. The heaviest configuration was the H-IIA 204 with four SRB-As or A3s which made five launches, all with large geosynchronous satellites.

During the early years of the program, two intermediate configurations were flown, the H-IIA 2022 and 2024. These used the smaller U.S.-built Castor-4AXL boosters in addition to a pair of SRB-As, with the 2022 fitted with a pair of Castors and the 2024 with four. Both of these configurations were retired following the introduction of the SRB-A3 as its increased performance
rendered them obsolete. The H-IIA 2022 made three launches between 2005 and 2007, while the 2024 flew seven times between 2002 and 2008.

H-IIAs first five launches were successful. During the sixth launch, which carried a pair of reconnaissance satellites for the Japanese government, one of the SRB-A motors failed to separate from the first stage, and the rocket was subsequently destroyed by range safety after it became clear that it
would not be able to make it to orbit. Ahead of Saturdays launch, the sixth flights mishap remains the only blemish on H-IIAs otherwise exemplary record.

Over its career, H-IIA has deployed a host of science and technology demonstration satellites for JAXA. These included both previous GOSAT and
both previous GCOM missions; the Global Precipitation Mission (GPM) Core satellite to measure global rainfall in partnership with NASA and the Hitomi (ASTRO-H) x-ray telescope which malfunctioned shortly after launch; and its replacement, XRISM. H-IIA F-40 launches GOSAT-2 in 2018 (Credit: JAXA)

In September 2007, an H-IIA launched the Kaguya orbiter towards the Moon, and in 2010 the rocket made its first interplanetary launch when it deployed the Akatsuki (PLANET-C) mission bound for Venus. Hayabusa 2 was launched on its mission to the asteroid (162173) Ryugu in 2014, and in 2020 another H-IIA boosted Al-Amal Hope the first Mars mission from the United Arab Emirates, toward the Red planet.

Closer to home, H-IIA has deployed four Himawari weather forecasting satellites; five spacecraft for the Quasi-Zenith Satellite System (QZSS), intended to enhance satellite navigation in Japanese cities; and data relay satellites for other spacecraft. A large number of H-IIAs missions were dedicated to building and maintaining Japans fleet of optical and radar reconnaissance satellites. Seventeen launches deployed a total of 21 satellites for the Cabinet Satellite Information Centers Joho Shushu Eisei (JSE), or Information Gathering Satellite (IGS), series.

In 2015, H-IIA carried out the first of two commercial launches of foreign communications satellites, the first such contracts to be won by a Japanese rocket. H-IIA F-29 deployed the Telstar 12V for Canadian operator Telesat.
Six years later, in December 2021, H-IIA F-45 carried the Inmarsat-6 F1 satellite into orbit. The DSN-2 satellite, launched in 2017, was operated by Japans commercial DSN Corporation on behalf of the countrys Ministry of Defense. The H-IIB, developed from H-IIA, was used to launch Kounotori resupply missions to the ISS (Credit: JAXA)

A more powerful rocket, H-IIB, was developed from H-IIA to carry out cargo missions to the International Space Station using the H-II Transfer Vehicle (HTV), or Kounotori . This flew nine times between 2009 and 2020, all successfully.

JAXA and MHI have developed the new H3 rocket as a successor to the H-II family, including both the H-IIA and H-IIB. H3s maiden flight took place in March 2023, but the vehicle was lost after its second stage failed to ignite. H3 posted its first successful launch on the second attempt , in February 2024, and has since flown three more successful missions. This new rocket builds on the legacy and success of the H-II family.

H-IIA F-50 will lift off from the same launch pad that was used for the previous 49 H-IIA missions and the H-II before that: Pad 1 of the Yoshinobu Launch Complex of the Tanegashima Space Center, located on the island of Tanegashima off Japans south coast. This is one of two launch pads that make up the Yoshinobu complex, whose second pad was originally built as a backup for H-IIA, was later used by the H-IIB and now serves as the launch pad for H3. Rockets are assembled vertically atop mobile launch platforms in a
vehicle assembly building (VAB) approximately 500 m to the northwest and rolled out a few hours before the scheduled liftoff. Artwork on H-IIA F-50 commemorating the final flight (Credit: JAXA)

It will take H-IIA F-50 about 16 minutes to deploy GOSAT-GW into orbit. After lifting off, the rocket will fly south from Tanegashima as it ascends through the atmosphere. About 108 seconds into the flight the SRB-A3 motors will burn out, separating 16 seconds later. Four minutes and 20 seconds after liftoff, the payload fairing will separate from around GOSAT-GW at the nose of the vehicle.

The first stage will burn for six minutes and 38 seconds before main engine cutoff (MECO) occurs, with stage separation expected eight seconds later.
Nine seconds after staging, the second stage will ignite for its burn. The second stage will fire for eight minutes and 15 seconds, with spacecraft separation due at 16 minutes and one second mission elapsed time, 51 seconds after second stage engine cutoff (SECO).

Saturdays launch is Japans second of 2025, following an H3 mission in
February that deployed a satellite for the QZSS navigation system. Japans
next orbital launch is expected to be a test flight of the H3-30S, a version of H3 optimized for smaller payloads, although a launch date has not yet been announced.

(Lead image: Previous H-IIA on the pad ahead of a launch. Credit: JAXA)



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https://www.nasaspaceflight.com/2025/06/gosat-gw-launch/


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