Japan has launched the Himawari 9 weather satellite on Wednesday afternoon local time, with the aid of its H-IIA rocket. Liftoff from the Tanegashima Space Centre, in Japan’s Osumi Islands, was on schedule at 15:20 local time (06:20 UTC), which was the opening of an available window of two-hour, 58-minutes.
Himawari 9 is the second of two third-generation satellites in Japan’s Himawari weather-monitoring series. Alongside Himawari 8, which was launched in October 2014, it is expected to provide the Japan Meteorological Agency (JMA) and the Ministry of Transport with observational data into the late 2020s.
Himawari – meaning sunflower – is a series of spacecraft which began in July 1977 with the launch of Geostationary Meteorological Satellite 1 (GMS-1) which took on the name Himawari after reaching orbit. GMS-1 was the first of five American-built first-generation satellites, whose launches continued until March 1995.
Constructed by the Hughes Aircraft Company, GMS-1 used an HS-335 bus while the later satellites were based on the HS-378 platform. GMS-1 also launched aboard an American rocket – a Delta 2914 – however all other satellites in the series were launched by Japan.
GMS-2 and GMS-3, which became Himawari 2 and 3 respectively on orbit, were launched in 1981 and 1984 atop N-II rockets – a version of the Delta built and launched under license in Japan. GMS-4 lifted off atop an H-I rocket, which incorporated a Thor-derived first stage and a Japanese second stage, in September 1989. The final Hughes-built Himawari, GMS-5, was launched by an H-II – a wholly-Japanese vehicle – in March 1995.
The GMS-type satellites were to be replaced by the Multifunctional Transport Satellite (MTSAT) spacecraft. MTSAT-1 was launched aboard an H-IIS – an enhanced version of the original H-II vehicle which was only used for the one launch, also the final flight of the original H-II design – but was lost following a turbopump failure on the first stage of the rocket.
When the ageing Himawari 4 ceased operations a few months later, the JMA was left with only Himawari 5 – itself already at the end of its design life – in operable condition. When Himawari 5 began to fail in 2003 the GOES-9 satellite was loaned from the US National Oceanic and Atmospheric Administration (NOAA) as a temporary replacement.
A replacement for MTSAT-1 – MTSAT-1R – was orbited by an H-IIA in February 2005, becoming Himawari 6 after its successful deployment allowing GOES-9 to return to NOAA. MTSAT-2 was launched a year after MTSAT-1R and became Himawari 7. The MTSAT-1 and 1R satellites were built by Space Systems/Loral; MTSAT-2 was constructed by Mitsubishi Electric.
Himawari 8 and 9 were developed to replace the MTSAT spacecraft; unlike their predecessors, these satellites have not been known by different names before launch. Himawari 8 was successfully launched by an H-IIA in October 2014 and entered service on 7 July 2015.
Himawari operations call for only one operational satellite at a time, so with Himawari 8’s entry into service Himawari 7 became the constellation’s on-orbit spare satellite and the previous spare, Himawari 6, was decommissioned. Himawari 9 will initially replace Himawari 7 as the spare satellite before swapping roles with Himawari 8 in five or six years’ time. The satellites will be stationed together in geostationary orbit, at a longitude of 140 degrees East.
The Himawari 8 and 9 satellites were constructed by Mitsubishi Electric and Boeing, using the same DS-2000 bus that was used for MTSAT-2. The spacecraft have design lives of fifteen years; however their instruments have an operational lifespan of eight years – hence the need to swap the primary and backup satellites over halfway through their missions.
After swapping roles, Himawari 8 will serve out the remainder of its design life as a backup to Himawari 9 prior to the launch of new satellites at the end of the next decade.
The 3,500-kilogram (7,700 lb) Himawari 9 satellite is equipped with the same three instruments as Himawari 8. Its primary instrument, the Advanced Himawari Imager (AHI) will be used in the production of full-disc and area images of the Earth. Operating at a resolution of up to 500 metres (1,640 ft), AHI allows multispectral imaging across sixteen channels and will be used to study cloud cover, winds, temperatures, precipitation and the distribution of aerosols in the atmosphere.
The Space Environmental Data Acquisition Monitor (SEDA) will record proton and electron fluxes in the spacecraft’s orbit, helping to characterise its radiation environment. Himawari’s third payload, the Data Collection Subsystem, is used to relay data from remote ground weather stations.
Himawari 9 rode to orbit atop an H-IIA rocket. Built and operated by Mitsubishi Heavy Industries the H-IIA is a two-stage liquid-fuelled rocket, which will be making its thirty-first flight. Since its maiden flight in August 2001 the H-IIA has achieved twenty-nine successes, its only failure coming on the sixth launch – which carried a pair of IGS reconnaissance satellites in November 2003 – when one of the solid rocket motors attached to the first stage failed to separate.
For Wednesday’s launch the H-IIA flew in its 202 configuration, which uses two SRB-A3 solid rocket motors to provide additional thrust at liftoff. This is the less-powerful of the rocket’s two operational configurations, compared to the 204 configuration which uses four boosters. Two intermediate versions, the 2022 and 2024 – which used two SRB-A motors and two or four Castor-4AXL boosters – were common during the rocket’s early years but are no longer in use.
The flight number for Wednesday’s mission was H-IIA F31. The rocket used a 4S-type fairing, the standard payload fairing for an H-IIA.
H-IIA launches take place from Pad 1 of the Yoshinobu Launch Complex at the Tanegashima Space Centre. Located in the Osumi Islands, off the south coast of Kyushu, Tanegashima has been used for orbital launches since the introduction of the N-I vehicle in 1975 and was used by sounding rockets before that. The Yoshinobu complex was constructed for the H-II in the early 1990s, replacing the nearby Osaka Launch Complex that had been used by the N-I, N-II, H-I and J-I rockets.
Yoshinobu consists of two launch pads; Pad 1 has been used since the H-II’s maiden flight in February 1994, while the second pad was added in 2000 was intended as a backup for the H-IIA. In practice, the H-IIA has exclusively used Pad 1, while Pad 2 has been used by the larger H-IIB rocket that deploys Kounotori resupply vehicles to the International Space Station.
The pads are served by a shared integration facility, where rockets are assembled vertically atop a mobile launch platform which is moved to the launch pad around half a day before liftoff.
The first stage of the H-IIA is powered by an LE-7A engine, fuelled by liquid hydrogen and liquid oxygen. Following ignition of the first stage engine, the H-IIA ignited its twin solid rocket motors and lifted off at the zero mark in its countdown. Ascending from Tanegashima across the Pacific Ocean, H-IIA F31 assumed a launch azimuth of 96 degrees.
The SRB-A3 motors burned for the first ninety-eight seconds of flight before burning out and separating ten seconds later. Following booster separation, the first stage continued to provide thrust as the rocket climbed towards space.
Once the rocket cleared Earth’s atmosphere, the payload fairing was no longer required to protect the satellite and was jettisoned to save weight. Fairing separation occurred approximately four minutes and five seconds after liftoff, with the rocket at an altitude of 142 kilometres (88.2 miles, 76.7 nautical miles).
The first stage burned for the first six minutes and thirty-six seconds of the ascent, at the conclusion of which it shut down its engine. Eight seconds after cutoff, the spent first stage separated, having propelled the vehicle to an altitude of 222 kilometres (138 miles, 120 nautical miles) and a velocity of 5.3 kilometres per second (3.3 miles per second). The second stage ignited six seconds after stage separation.
During Wednesday’s mission the second stage’s LE-5B engine performed two burns. Like the first stage, the second stage burns liquid hydrogen and liquid oxygen. Its first burn lasted five minutes and 22 seconds, after which the mission entered a coast phase. After coasting for eleven minutes and 38 seconds, the stage restarted for its second burn, lasting three minutes and seventeen seconds.
Himawari 9 separated from the H-IIA fifty seconds after the conclusion of the second burn. The mission profile from liftoff to spacecraft separation is identical, down to the individual burn durations, to the 2014 launch of Himawari 8.
The target orbit for Wednesday’s mission is a perigee of 250 kilometres (155 miles, 135 nautical miles), an apogee of 35,976 kilometres (16,141 miles, 14,026 nautical miles) and inclination of 22.4 degrees to the equator. From this transfer orbit, Himawari 9 will manoeuvre itself into geostationary orbit.
The launch of Himawari 9 was Japan’s second of 2016, following the launch of the Hitomi – or ASTRO-H – satellite atop another H-IIA in February. Japan is aiming to carry out one more launch before the end of the year, with an H-IIB slated to launch Kounotori 6 to the International Space Station on 9 December. The next H-IIA launch is currently scheduled for January next year with the DSN-2 communications satellite.
Himawari 9 is the first of two geostationary weather satellites expected to be launched this month. The National Oceanic and Atmospheric Administration’s GOES-R spacecraft is currently scheduled for launch aboard an Atlas V rocket on 16 November from Cape Canaveral. GOES-R will be the first of a new generation of US weather forecasting satellites.
(Images via JAXA).