H3, Japan’s Bid for Space Access in a Competitive World

Artist’s Impression of H3 flying in the two booster configuration.
Credit: JAXA

On the 7th of March, the Japan Aerospace Exploration Agency launched the inaugural mission of their H3 rocket. After over a decade in development, the launch was highly anticipated, and with the final four launches of H3’s predecessor scheduled, the successful launch of H3, carrying the ALOS-3 mission, would ensure Japan a foothold in today’s launch market, and avoid a gap in national launch capabilities. ALOS-3, however, was not successfully launched, as the second stage of H3 failed to light. The self-destruct command was sent around 10 minutes into the flight and the payload was lost.

The incident is under investigation by an assembled task force headed by JAXA president Hiroshi Yamakawa, and the results of the failure on the scheduling of future H3 launches, including a handful planned for this year, remain uncertain. The 50th and final launch of H-IIA which H3 is meant to replace is scheduled for JFY2024. JAXA grounded H-IIA in the immediate aftermath of the ALOS-3 failure, in order to determine if the cause of the incident is shared with H-IIA, however H-IIA launches are expected to resume next week with the launch of XRISM on August 27. With only a few H-IIA launches left, the possibility that H3 may not be ready by the time the H-II family retires is very real.

H3 lifts off on its maiden flight on March 7th, 2023.
Credit: JAXA

H3 has been in some stage of development as far back as 2010, when its main engine was in its earliest stages of prototyping. This alongside its nature as an expendable launch vehicle in an era of operational and upcoming reusable lifters make it easy to dismiss H3 as an outdated rocket which was delayed past the time where it would’ve been competitive and practical. This understanding is without a doubt common in reports on H3, and overall the shift to emphasizing reusability in upcoming launch systems has been difficult for government/commercial hybrids to adopt. However, focusing solely on if a rocket is reusable or not  overlooks steps taken to adopt new technology and manufacturing methods that bring down cost and lead time. An expendable system is not inherently one without any merit whatsoever.

H3’s stated goals are high flexibility, high reliability, and high cost performance, and its prime contractor, Mitsubishi Heavy Industries (MHI), has taken numerous steps to achieve said goals. H3 has a variety of different launch configurations, comprising two different fairings with differing volumes, the ability to have either two or three LE-9 main engines, up to four solid rocket boosters, or none at all. This diversity of configurations means that H3 can be adapted to a diversity of mission profiles in both low orbit and GTO. Additionally the SRB-3 solid rocket motor developed for H3 will also form the first stage of the Epsilon S small launcher, upgrading the Epsilon system while minimizing development costs. This versatility and synergy with Epsilon mean H3’s development program provides advantages for Japanese space access across missions of all sizes.

Line up of H-II and H3 configurations, showing the vehicle’s versatility.
Credit: Mitsubishi Heavy Industries

Beyond offering a variety of configurations H3 also represents an increase to payload capabilities previously offered by H-IIA. H3’s primary focus in terms of expanding capabilities was increasing the total payload that could be delivered to geostationary transfer orbit. While payload capacity to low orbit and sun-synchronous orbit, (SSO being the target of ALOS-3), is not dramatically higher than that offered by H-IIA, the payload to GTO has increased from around four tons to over six and a half. Even across capabilities already offered by H-IIA, H3 represents a dramatic reduction in cost, halving the cost of H-IIA. This combined with streamlined production, aspirationally, would allow for a doubling of Japan’s launch cadence from four per year, optimally, to eight once H3 enters full operations.

The basis of H3’s reliability claims lie in its heritage hardware with H-IIA, and modifications made to simplify that hardware. The LE-5B upper stage engine which has a long and reliable flight record operating on H-IIA was carried over to H3 with some modifications made to reduce cost and improve performance as LE-5B-3. LE-5B also forms the basis of LE-9, the main engine, which provides higher reliability and lower complexity over the LE-7 used on H-IIA, namely through LE-9’s usage of an expander bleed cycle. The separation systems used for SRB-3 have also been simplified to reduce failure points, and the SRBs themselves use much of the same flight-proven hardware and materials of their predecessors while adopting fixed nozzles to remove yet another point of complexity.

Twin LE-9s firing during the fourth Battleship Firing Test (BFT) of an H3 first stage.
Credit: JAXA

Running counter to its claims of reliability, however, is of course the fact that H3 failed its first mission, and unlike other experimental launch vehicles its first mission did not carry a dummy payload, but an operational one. The failure cost JAXA its ALOS-3 spacecraft, which according to a report by the Japanese Ministry of Education, Culture, Sports, Science and Technology, was valued at around 28.2 billion yen, or about $198 million USD. The Advanced Land Observing Satellite, the third of its lineage, would’ve provided high resolution orbital observations of regions across the world, with emphasis on providing detailed imagery that could be used in disaster relief efforts. ALOS-4 was already in active development before ALOS-3 launched, and was scheduled to be the payload of H3’s second launch. However in light of the rocket’s failure, launching the even more expensive payload on H3’s second flight no longer seems to be the plan.

It is worth the reminder, however, that the most experimental aspects of H3’s design operated as expected for the first launch. The LE-9 main engines and SRB-3 boosters functioned perfectly for their first operational launch; it was the failure of the upper stage engine to light that cost H3 a successful mission. An abundance of caution was allotted to LE-9 in the last three years of its development, rigorous stress testing was employed to iron out any possible failure that could occur. While the launch was delayed by engine issues, the rest of the vehicle moved forward. Redesigns to the turbopumps and combustion chamber ran alongside the assembly and testing of the first launch vehicle. While LE-9 technically poised the greatest risk to the success of H3’s inaugural launch, this hyperfocus may have in turn resulted in insufficient attention towards the novel aspects of H3’s design. The upper stage, which is largely heritage hardware, may not have been granted the scrutiny it deserved, and could’ve had if development on other subsystems was slowed to use to the time opened by engine delays. If true, H3’s failure serves as a harrowing reminder not to take any aspects of a mission for granted, though with what is known publicly we cannot say for certain. What can be said however is that LE-5B-3 is built off an engine that JAXA and MHI already have great experience with, and whatever the precise cause of the failure is, the technical knowledge necessary to amend it is surely less significant than would be required if a newer piece of hardware was the mission’s failure point.

H3 sits on the pad during its wet dress rehearsal.
Credit: JAXA

Furthermore, a failure on its inaugural launch by no means dooms H3 to forever be an unreliable vehicle. The iconic Ariane 5, which at time of writing retired just days ago, is considered by many one of the most reliable launch vehicles in history; the last time an Ariane 5 launch would result in the loss of a payload was back in December of 2002, over two decades ago. However, Ariane 5 similarly experienced a dramatic failure on its first launch in June of 1996, a software error caused the vehicle to drift off-course, beginning to disintegrate due to increased aerodynamic stress, which then triggered a self-destruct just 37 seconds into flight. The first Ariane 5 also brought down an operational payload, much like H3 did, one that was even more expensive. Of course, while Ariane 5’s failure was more visually dramatic, it was not an error of hardware, as is the case for H3. It is difficult to compare the effects of a software issue in the late 90s to a hardware fault today, but judging by Ariane 5’s turn around and the high reliability of H-IIA, there is little reason to assume H3 will not find its footing and establish itself as a rocket with a similar reputation of reliability. The question then becomes when it will do so, the answer to which will remain unknown until JAXA announces their plan for H3’s second flight, which has not happened yet.

H3’s structure is largely derived from that of well proven H-IIA, however it has been streamlined, the number of parts and the complexity of their assembly have both been drastically reduced. Furthermore, along its long developmental history, Mitsubishi has been more than willing to adopt new manufacturing methods to further reduce the time and complexity of manufacturing for H3, employing 3D printing in the production of the LE-9 engine, particularly with its injectors and expected to be introduced into the production of its combustion chamber down the line. While this implementation is nowhere near the extensive usage of 3D printing being pioneered commercially by companies like RocketLab and Relativity, even ArianeGroup successfully tested their own 3D printed combustion chamber in 2020, the fact it exists at all is an important step in ensuring H3’s cost remains somewhat competitive.

Production of components to H3 also involves tactics that are less new, but still represent significant improvements over those used to manufacture H-IIA. For instance its tankage makes use of “integrally formed deep spinning dome,” which reduces the amount of parts used and steps required to produce the base structure of the tank ends by using a tactic that bends a singular sheet of metal into the proper shape. Mitsubishi also employs an automated drilling and riveting machine, a robotic arm which takes over assembly roles which previously required human labor, for H3’s main structure. MHI’s technical review from December of 2021 also describes the usage of “off-the-shelf components” from automobiles and aircraft used “to the maximum extent possible” for H3’s avionics, though the specific details of what these components are is not made clear. Another report from December of 2017 details that the parts used were extensively tested to ensure every opportunity in which off-the-shelf components could be integrated without harming performance was taken.

Cost reduction techniques used in the manufacturing of H3
Credit: Mitsubishi Heavy Industries

All of these factors are promising, and as things stand H3’s pricing is competitive, with the base vehicle’s currently anticipated pricing of $50 million per launch undercutting even the market price of SpaceX’s Falcon 9 Block 5. However, in today’s market the present and future potential of a vehicle cannot be accurately assessed without addressing the matter of reusability, and in this case, H3’s lack thereof. Streamlined manufacturing, while its value is often unstated, is an important pursuit when competing in the launch market, ULA’s Vulcan and Arianespace’s Ariane 6, like H3, will both initially launch on the grounds that improvements made to production pipelines will reduce their costs. Making the production of an engine, a fuel tank, or an entire stage cheaper is without a doubt important, but it is only the next best thing compared to making those components able to support multiple launches.

ULA and Arianespace recognize this, Vulcan is expected to eventually perform so-called “SMART reuse,” which has been part of ULA’s vision for Vulcan for years now, and refers to the recovery, recertification, and relaunch of the vehicle’s engine section. Arianespace, while it has not has reusability in mind with Ariane 6 for nearly as long, detailed in September last year their plan to eventually employ reusable liquid fuel boosters on the vehicle, in the hopes of reducing the cost of Ariane 6 and paving the way for a future system based on reusability from the start. The Prometheus engine which will enable this evolution of the system entered testing last November. 

With all this in mind, it is disheartening to see that H3 has no declared plans of employing even partial reusability in its future. While recognizing reusability as “essential” to the future of Japanese launch capabilities, Mitsubishi’s 2021 report does not recognize any plans to introduce reusability to H3. Rather that a separate vehicle referred to as an “innovative future transport system” will enter development alongside upgrades and improvements to H3. The roadmap referred to was presented by the Ministry of Education, Culture, Sports, Science and Technology and calls for a subscale demonstration vehicle in 2026, an operational vehicle with first-stage recovery launching in 2030, and a fully reusable vehicle in 2040. While it has not been greenlit by JAXA, the haste of the proposal raises questions of how long H3 will remain a competitive lifter even in its home country. No matter how promising the immediate future may seem for the vehicle, in a few years, H3 could find itself as one of the only new rockets without even a long term plan to implement reuse. Cadence is also a point of trouble for H3, while it should provide a major upgrade to Japan’s national launch cadence, the anticipated rate of eight flights per year is not competitive globally. Falcon 9 launched 60 times in 2022, and ULA’s Vulcan is aiming for a similar flight rate.

A pathway by which H3 could grant Japan Lunar cargo capabilities, but does not grant the vehicle any form of reusability.
Credit: Mitsubishi Heavy Industries

In the face of these technical limitations, it is no surprise that H3 has had difficulty finding customers, in 2017 MHI signed a deal with Inmarsat to launch the Inmarsat-6 F1 communication satellite aboard H-IIA. The deal also secured the launch of an Inmarsat satellite on a future H3 flight, however the exact satellite H3 is going to launch has not been stated, and beyond this singular launch H3 has failed to find private customers. In the wake of its failure, it is unlikely to find any until it has a successful flight, and it will remain to be seen if it finds any once it does.

While private enterprises do not have much interest in H3 at this point, H3 will be handling Japanese government payloads, ranging from spy satellites to weather satellites such as a successor to Himawari. H3 will launch JAXA planetary science payloads such as the ambitious Martian Moons Explorer (MMX) which seeks to explore the moons of Mars and return samples from Phobos, currently scheduled for next year, it is unclear if H3’s failure will cause the launch to slip. H3 will carry HTV-X, the successor to the H-II transfer vehicle, which will bring cargo to the International Space Station, once again the scheduling is unclear in the wake of the ALOS-3 failure. H3 is also one of Japan’s contributions to the Lunar Polar Exploration Mission (LUPEX), also known as Chandrayaan-4, an international mission with India to send a robotic Indian lander and Japanese rover to the Lunar south pole as part of India’s larger Chandrayaan Program. H3’s lunar prospects continue as it will also serve a cargo role in the Artemis Program, where it will deliver cargo to the Lunar Gateway Station around the Moon via a further evolution of HTV, though the outline of these flights is unclear.

An artistic rendering of the LUPEX mission, with the Japanese rover departing its Indian landing platform.
Credit: JAXA

All things considered, while it is unlikely to occupy a large portion of the international launch market, H3 shows the potential to provide reliable launch services in the near future. If it were not for the current disinterest displayed by commercial enterprises, the current pricing of H3 and Ariane 6 would give MHI a significant advantage. Ariane 6 is the successor to a vehicle which totally embodied the goals of H3, and seeing that pedestal taken from Arianespace by MHI would be a significant shift. All that potential, however, is sealed behind a successful return to flight, and whether or not H3 can be turned around fast enough to garner the attention of consumers looking for a cost-effective alternative. Regardless of if H3 finds customers however, it is guaranteed to provide a ride to space for Japanese national payloads, and grounds for international contribution with other nations in space. The latter is a major element of H3’s styling, as it is the first member of its lineage to display the international name “Japan”  upon its tankage as opposed to the native name “Nippon,” an adjustment four decades in the making. As stated by Isao Kotani during the broadcast of H3’s first launch, the change was made in “the hope that people all over the world will use [H3],” it represents a hope to shift the presentation of Japanese space launch from national pride to international service. While it won’t be disruptive towards the market by any means, H3 seems well poised to live a quiet and humble operational life through the 2020s, and likely a bit beyond, perhaps representing the final generation of purely expendable rocketry in the modern age of spaceflight.

Edited by Nik Alexander, Beverly Casillas

While writing this article, on July 14th, a test firing of Epsilon S’s second stage resulted in an explosive failure halfway through its expected duration. While the failure of Epsilon S’ second stage is not necessarily relevant to H3 in terms of hardware, this further exacerbates the genuine risk of a gap in Japanese launch capabilities.

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