H3 Rocket No. 9 launch successful — Carries Quasi-Zenith Satellite Michibiki No. 7

Large rocket "H3" No. 9 was launched from the Tanegashima Space Center in Kagoshima Prefecture at 4:23:31 a.m. on the 11th. Placing the government's Quasi-Zenith Satellite "Michibiki" No. 7 into a predetermined orbit, the launch was successful. For H3, following the failure in December last year, this is a success continuing on from June this year, taking a step toward stable operation. Michibiki, which is the Japanese version of GPS (Global Positioning System) satellites, lost one unit during a launch failure. The realization of the seven-satellite system aimed for by the government has been postponed.

"Approached it with the determination never to fail again"

H3 separated its first and second stage airframes approximately 5 minutes after launch. After normally performing combustion of the second-stage engine twice, approximately 29 minutes after launch, it placed Michibiki No. 7 into geostationary transfer orbit. Although the launch was planned for the 7th, it was postponed due to the approach of a typhoon. President Hiroshi Yamakawa of the Japan Aerospace Exploration Agency (JAXA), who held a press conference after the launch, stated: "The fact that stakeholders from many institutions united to work carefully and reliably will lead to refining Japan's space transportation system into something more stable and highly reliable."

H3 is the successor to "H2A," which ended operation in June last year, and its enhanced type "H2B." A two-stage liquid-fuel rocket, No. 9 has an overall length of 57 meters and a weight of 422 tons excluding satellites. Depending on airframe configuration, capacity reaches over 6.5 tons at maximum (geostationary transfer orbit, converted for launch at the equator), exceeding H2B's 6 tons. Along with the small solid-fuel rocket "Epsilon," it is positioned as a flagship rocket of the government. In the future, launch operations will be transferred from JAXA to Mitsubishi Heavy Industries as with H2A, enabling entry into the market. No. 9 was equipped with two first-stage engines and two solid rocket boosters, similar to Nos. 1 through 5 and No. 8.

The maiden unit of H3 was launched in March 2023 but failed due to being unable to ignite the second-stage engine, losing an Earth observation satellite. The cause was an electrical system anomaly in the second-stage engine. Three countermeasures were implemented to address events that could have been causes. Afterward, it succeeded five consecutive times, but No. 8 failed in December last year, losing Michibiki No. 5. The cause was that detachment occurring during manufacturing inside the adapter mounting the satellite onto the airframe expanded due to impacts during flight. Unlike H2A, to reduce weight and costs, the adapter of H3 was assembled by bonding components made of carbon fiber reinforced plastic (CFRP). As a countermeasure, for No. 9 and onward for the time being, it was decided to assemble using the bolt-securing method adopted in H2A.

Project Manager Makoto Arita of JAXA stated: "Since the failure of No. 8, we have devoted all efforts to working toward restoring trust. Continuing from the previous No. 6 (in June, which did not carry a large satellite), to finally return to practical use this time, we were able to approach the launch with the determination never to fail again. We were able to raise the signal flare for restarting practical use. We have kept many customers waiting, but they can 'ride' H3 with peace of mind."

Project Manager Osamu Kitayama of Mitsubishi Heavy Industries, who develops H3 together with JAXA, expressed recognition stating: "We must continue to succeed. H3 must be a rocket that evolves, and design change points will emerge. Lowering costs without dropping quality is a major challenge."

According to the government's Implementation Plan of the Basic Plan on Space Policy (revised December last year), during this fiscal year, launches via H3 are planned for cargo resupply vehicle "HTV-X" No. 2 to carry supplies to the International Space Station (ISS), and an exploration vehicle for "MMX" to explore Mars's moon "Phobos" and bring samples back to Earth.

7-satellite system aiming for high precision, delays in infrastructure development

GPS is a mechanism that receives radio waves emitted from satellites on the ground, calculates distance from time taken for arrival, and identifies positions on the ground. Besides being widely used in smartphones and car navigation systems, utilization in automated driving of cars and agricultural machinery, and material transportation via drones is expected. It is also used for precise time synchronization, supporting mobile communications, financial transactions, power grid management, and more. To calculate positions and time, at least four satellites are required in principle.

Following the United States building GPS ahead of other countries, Europe, Russia, China, and others developed unique positioning systems. Japan also adopted a unique "quasi-zenith orbit" above Asia and Oceania, and began infrastructure development for Michibiki. In 2017, a basic system of four satellites was arranged, and service formally commenced the following year.

When adopting a quasi-zenith orbit, flight time becomes longer near directly above Japan (quasi-zenith). Considering a state where Earth's rotation is stopped, it is an orbit where the satellite moves as if drawing a figure eight, devised in 1972 by a researcher at the former Radio Research Laboratory of the Ministry of Posts and Telecommunications (currently the National Institute of Information and Communications Technology). Among satellites called quasi-zenith satellites, some actually adopt geostationary orbits or quasi-geostationary orbits rather than quasi-zenith orbits. Geostationary satellites fly above the equator and appear stationary from the ground. No. 7 this time is a quasi-geostationary satellite, and by flying slightly tilted against the equator, appears to move only a little from the ground. By creating a distinction from other geostationary satellites, inconvenience in positioning calculation can be avoided, and service suspensions due to orbit adjustments can be kept to the minimum.

Three satellites in quasi-zenith orbit and two geostationary satellites are in operation, and No. 7 joins them. With solar panels unfolded, overall length is approximately 19 meters, and weight at launch is approximately 4.9 tons. Development costs were approximately 100 billion yen in total for lump-sum procurement of three satellites including Nos. 5 and 6. Launch costs are undisclosed.

By starting the seven-satellite service in this fiscal year, the government aimed for a system capable of demonstrating sufficient precision without relying on foreign systems such as US GPS. However, No. 5 failed in December last year, and even if No. 7 this time starts full-scale operation, it has become a situation where there are only six satellites. With No. 8 launched in fiscal year 2031, the seven-satellite system is expected to be completed. For the time being, operation with six satellites continues, but going forward, by adjusting positions of existing satellites, regions with high positioning precision will be expanded somewhat.

No. 7 was equipped with the "Advanced Satellite Navigation System (ASNAV)," continuing from No. 6. It is a mechanism that not only receives signals from satellites on the ground, but also where satellites measure distances between other satellites or measure distances to the ground to cancel out errors. When all quasi-zenith satellites are equipped with this system in the future, positioning precision even on general smartphones will improve from the current 5 to 10 meters to approximately 1 meter. JAXA was in charge of development under commission from the Cabinet Office. However, No. 5, which was equipped with inter-satellite range-finding transmission functions, has been lost. For this reason, demonstration of inter-satellite range-finding must wait for No. 8, which will be equipped with transmission functions.