Japan’s H-IIA rocket has made its second flight of the year Thursday, carrying a new-generation optical imaging satellite for the country’s military. The launch of IGS Optical-5 occurred on schedule at 10:21 local time (01:21 UTC), setting sail from the first pad of the Tanegashima Space Centre’s Yoshinobu Launch Complex.
Thursday’s launch carried the fourteenth spacecraft in Japan’s Joho Shushu Eisei (JSE) series of satellites, commonly known in English as the Information Gathering Satellites or IGS. The IGS programme, which is operated by Japan’s Cabinet Satellite Intelligence Centre, consists of optical and radar imaging spacecraft.
The IGS programme was initiated by Japan following North Korea’s attempted launch of the Kwangmyŏngsŏng-1 satellite in August 1998; a launch which overflew Japan and raised concerns about North Korea’s ability to develop a rocket capable of attacking Japan.
The satellites are constructed by Mitsubishi Electric and launched by Mitsubishi Heavy Industries using the H-IIA rocket.
The first pair of IGS satellites – one carrying an optical imaging payload and the other a radar imager – were launched together in March 2003. After another dual launch the same year ended in failure, IGS launches were postponed until the deployment of a lone optical satellite in 2006. A radar spacecraft followed in 2007, launching with a prototype second-generation optical satellite.
The constellation entered it second generation of satellite in November 2009 with the fourth IGS Optical spacecraft; another second-generation optical spacecraft followed in September 2011.
The radar element of the constellation has also entered its second generation, with spacecraft launching in December 2011 and January 2013. The 2013 launch also carried a prototype for the third-generation optical IGS spacecraft, the operational version of which will be making its debut with Thursday’s launch.
A further second-generation radar satellite was deployed in January in order to provide the constellation with redundancy should a satellite be lost. The need for a spare satellite arose due to the poor reliability of the first-generation radar satellites, which both failed within four years of their launches.
Thursday’s launch carried the first third-generation spacecraft for the series, Optical 5. Taking advantage of systems demonstrated by 2013’s prototype mission, the Optical 5 satellite will be used to image the Earth’s surface in high resolution. The prototype was reported to have had a ground resolution of approximately 40 centimetres (16 in).
For Thursday’s launch the H-IIA flew in its 202 configuration. The smallest version of the H-IIA, the 202 has been used for all of its launches since a 2009 upgrade increased its performance and rendered the now-retired intermediate 2022 and 2024 configurations obsolete.
A two-stage vehicle, the rocket consists of fully cryogenic first and second stages; fuelled by liquid hydrogen and liquid oxygen. A pair of SRB-A3 solid rocket motors provide additional thrust to the first stage during the early phases of the flight.
The rocket that perform Thursday’s launch had the flight number F-28 and was the twenty eighth H-IIA to fly. Departing from Pad 1 of the Yoshinobu Launch Complex, or LA-Y, at the Japan Aerospace Exploration Agency’s (JAXA) Tanegashima Space Centre, the rocket carried its payload into a sun-synchronous orbit.
The Yoshinobu Complex consists of two pads, the first of which was built for Japan’s H-II rocket in the 1990s, with the second being constructed in the early 2000s as a backup pad for the H-IIA.
For this mission, the first pad was used by the H-IIA with the second plays host to the larger H-IIB, which is used for JAXA’s Kounotori resupply missions to the International Space Station.
The LE-7A engine which powers the first stage of the H-IIA ignited two to three seconds before liftoff.
When the countdown reaches zero, the vehicle ignited its SRM-A3 solid motors to begin the climb towards orbit. Although details of the mission profile have not been published, it is likely to have followed a similar flightplan to Japan’s previous launches into sun-synchronous orbits.
The solid rocket motors burned for the first 99 seconds of the flight before their thrust tailed off and they were no longer providing sufficient thrust to aid the vehicle’s ascent. Hydraulic actuators activated approximately nine seconds after the motors burn out to jettison their spent casings from the rocket.
The rocket’s payload fairing also separated during first-stage flight, likely around four to five minutes after liftoff.
The first stage’s fuel supply was depleted at around the six minute, fifty seconds mark in the flight, after which the vehicle coasted until stage separation eight seconds later. Six seconds after staging the LE-5B engine of the second stage ignited to begin its role in the launch.
Depending on mission parameters the second stage can either make a single burn with a duration of around eight minutes, or two shorter burns, to achieve the satellite’s operational sun-synchronous orbit. The single-burn profile, followed shortly be spacecraft separation, is the most likely scenario.
While there were unknowns, per the parameters of the ascent, a successful spacecraft separation was confirmed.
The sixteenth orbital launch of 2015 – including an uncatalogued Vega launch whose upper stage achieved orbit during test manoeuvres following a successful suborbital mission – Thursday’s was the second of the year for Japan and its H-IIA rocket.
It concludes a series of three launches in the space of seven hours, which began with United Launch Alliance’s Delta IV mission to deploy the GPS IIF-9 navigation satellite at 18:36 UTC (14:36 Eastern) Wednesday and continued with Russia’s Dnepr launching the Arirang-3A remote sensing satellite for South Korea at 22:08 UTC (03:08 Yekaterinburg Time).
Japan has three further launches scheduled for 2015, with the next scheduled departure that of an H-IIB with the fifth Kounotori, or H-II Transfer Vehicle (HTV), to carry supplies to the International Space Station. The HTV launch is slated for August, with the H-IIA next in action in November to deploy the New X-ray Telescope (NeXT), also known a ASTRO-H.
The final Japanese launch of the year is expected to be the country’s first ever dedicated commercial launch, with an H-IIA carrying the Telstar 12V communications satellite to geostationary transfer orbit.
(Images via JAXA and @koumeiShibata)