The Japan Aerospace Exploration Agency (JAXA) and Mitsubishi Industries have conducted the nation’s first orbital flight of 2023. The mission saw an H-IIA rocket carry the classified IGS-7 radar reconnaissance satellite into a Sun-synchronous orbit.
Liftoff occurred on Thursday, Jan. 26, 2023, at 01:49:20 UTC from Launch Area Y1 at the Tanegashima Space Center in southern Japan. The launch window lasted just 61 seconds, closing at 01:50:21 UTC.
The mission is the first of several planned orbital launches for Japan in 2023; however, that flight rate hinges not just on payload availability but on the successful introduction of the H3 rocket, currently slated for no earlier than February 12, 2023.
The payload for this classified H-IIA mission was the IGS (Intelligence Gathering Satellite) 7 spacecraft for the Japanese government’s Cabinet Satellite Information Center.
Reports indicate a ground resolution of less than one meter for the Synthetic Aperture Radar (SAR) series of the overall IGS program, which also includes a series of optical satellites.
The newer generations of the system launched since 2015 have been capable of resolutions down to 30 cm for the optical range and 50 cm for the SAR range.
The IGS program was created in response to the 1988 North Korean missile test over Japan. The network is tasked, in large part, with providing early warning of impending hostile missile launches.
Information from the satellites is also used as part of civil natural disaster monitoring and response.
The exact orbital parameters were not known prior to launch; however, past IGS missions indicate a Sun-synchronous orbit with a perigee between 475 and 500 km and an apogee between 500 to 515 km with an inclination of approximately 97.4°.
H-IIA’s Retirement Year
Taking IGS-Radar 7 to orbit — as it has for all the other IGS missions — was the H-IIA rocket.
Operated by Mitsubishi Heavy Industries for JAXA, the H-IIA entered service on August 29, 2001. Four variants of the rocket have flown over the course of its career — though only one variant remains today.
The H-IIA flew this mission in the H2A 202 configuration, with the first number denoting the number of stages (2), the second representing the number of liquid-fueled boosters (0), and the third representing the number of SRB-A solid rocket boosters (2).
Just before liftoff, the H-IIA commanded the single LE-7A liquid engine on the hydrogen-oxygen first stage to ignite and build up to full thrust. After a brief series of health checks, commands were sent to simultaneously ignite the two SRB-A solid rocket boosters, release the rocket, and disconnect the T0 umbilicals — committing the vehicle to flight.
The twin SRB-As burned hydroxyl-terminated polybutadiene for 120 seconds before burning out and separating, leaving the first stage’s approximately 1,098 kN of thrust (247,000 lbf or 112 tonnes-force) to continue pushing the stack toward orbit.
After a 390-second burn, the first stage shut down and handed off to the rocket’s hydrogen-oxygen second stage, which used its single LE-5B engine to finish the climb to orbit.
The LE-5B engine produces approximately 137 kN of thrust (31,000 lbf or 14 tonnes-force).
After the IGS-Radar 7 mission, only four H-IIA missions remain as the rocket is set to retire on its 50th mission.
That retirement flight is currently planned for this year.
The H3 rocket is set to succeed the H-IIA, introducing numerous improvements and performance boosts while lowering the overall cost of the system.
The H3 is currently tracking toward a debut launch no earlier than Feb. 12, 2023, in a window that opens at 01:37:55 UTC and closes at 01:44:15 UTC.
The rocket is currently stacked in the vertical integration facility at the launch site after undertaking a static fire campaign on the launch pad in November 2022.
After initial installation, the second of the two SRB-3 boosters was reattached in late December after inspections on the H3 liquid core stage were needed.
The first mission will carry the ALOS-3 (Advanced Land Observing Satellite 3) into a Sun-synchronous orbit. The rocket will fly in its H3-22S configuration.
The final three digits of each H3 mission denote the rocket configuration. The first number indicates the number of first-stage LE-9 engines (2 or 3), the second digit signifies the number of SRB-3 boosters, and the final digit is either “S,” “L,” or “W” for the payload fairing.
The “S” is for a short fairing at 10.4 m long, and “L” is for the long fairing at 16.4 m. Both the short and long fairings are 5.2 m in diameter.
The “W” designation is for a wider 5.4 m diameter fairing that is the same length as the long variant.
For its first mission, the H3-22S will fly with a two-engine first stage, two SRB-3 boosters, and a short fairing.
Only three total propulsion configurations for the H3 are possible: H3-30, H3-22, and H3-24.
The first stage will carry 225 tonnes of propellant and oxidizer, while the second stage will carry 23 tonnes of propellant and oxidizer.
The first stage’s LE-9 engines burn hydrogen and oxygen, with the two-engine variant producing 2,942 kN of thrust (661,000 lbf or 300 tonnes force) whereas the three-engine variant will produce 4,413 kN of thrust (992,000 lbf or 450 tonnes force).
The H3’s upper stage’s LE-5B-3 engine will produce 137 kN of thrust (31,000 lbf or 14 tonnes-force).
While the H3 rocket will be a versatile vehicle in terms of the payloads it will launch, a main customer is JAXA’s upcoming HTV-X cargo resupply craft for the International Space Station.
HTV-X is a follow-on and upgraded version of the H-II transfer vehicle which flew from 2009 to 2020.
HTV-X will sport a 16 metric ton launch mass (comparable to HTV), with a payload-to-ISS capacity of 4.07 t in the pressurized volume and 1.75 t in the unpressurized section.
The pressurized section of HTV-X measures 78 cubic meters — far exceeding HTV’s pressurized volume of 14 cubic meters.
The craft will be capable of remaining docked to the ISS for up to six months, double the length of its predecessor. HTV-X will also be able to remain in orbit after leaving the ISS for up to 18 months to serve as a free-flying space station and technology demonstration platform.
HTV-X’s first launch, assuming the first year of operational service of the H3 rocket is successful, is currently planned for no earlier than January 2024.
(Lead image: An H-IIA rocket prepares for flight ahead of a previous mission. Credit: JAXA)