New generation H3 rocket ready to launch High performance & low cost, new engine is the trump card

The first launch of Japan’s next-generation large rocket “H3” is approaching on the 15th. It is the successor to the H2A, which has been in operation since 2001, and has achieved both high performance and low cost to cope with the increasing size of satellites, and will become a mainstay of space development and utilization. The trump card for realizing this was the new 1-stage engine “LE9”, which changed the design concept. Technical barriers loomed over the development team, and the debut was postponed for two years. “We want to complete the rocket just as we envisioned, and contribute to the world,” said a person concerned, who is preparing for the launch.

“The final scene of joining forces”

　”Development is almost complete, and we will start the launch work. I want to do my best in the final scene where many people are working together.”

　Masafumi Okada, project manager of the Japan Aerospace Exploration Agency (JAXA), who is leading the development of the H3, emphasized at a press conference held on December 20, 2017, following the results of the engine test in November last year, which was the final climax of development.

　This test is a “first stage actual tank stage combustion test”. It is positioned as the finishing touch to the engine test. As with the actual launch, at the Tanegashima Space Center (Minamitane-cho, Kagoshima Prefecture), H3 No. 1 was brought to the launch site and fuel was put in, and the two LE9s onboard were burned for 25 seconds. The aircraft is fixed to the launch pad and does not take off. It was a large-scale project to verify whether the entire system, including ground related equipment, functioned properly through a series of operations.

　Although there are some areas for improvement, the overall results are good. JAXA announced in late December that it will launch on the 12th of this month. After that, there were confirmation items, and as of the morning of the 10th, it was planned to be launched after 10:30 am on the 15th.

Conscious of the world, “JAPAN” on the aircraft

　The H3 is the successor to the H2A and the enhanced H2B, which operated until 2020, and is also a two-stage liquid-fuel rocket. The total length is 10 meters longer than H2A, up to 63 meters. It weighs 575 tons. The maximum capacity will be 6.5 tons or more, exceeding the 6 tons of H2B (equivalent to a geostationary transfer orbit, launch at the equator). Jointly developed by JAXA and Mitsubishi Heavy Industries, the development cost so far is 206.1 billion yen.

　The structure of the aircraft varies depending on the application. There is a pattern to install 2 or 3 LE9s with 1.3 times the thrust of the H2A 1st stage engine, and 0, 2, or 4 “solid rocket boosters” beside the 1st stage fuselage. The big difference from H2A is that it does not have a booster. The “fairing” that covers the satellite at the tip is also available in 3 different sizes. With a strong awareness of global penetration, it is eye-catching that “JAPAN” is written on the side instead of “NIPPON” up to H2A.

　The first unit adopts a pattern with two LE9s and two boosters, and carries JAXA’s advanced optical satellite “DAICHI-3” for photographing land.

A little sacrifice of fuel efficiency, simple mechanism

　The LE9 was the centerpiece of H3’s technology and the most difficult. Japan’s unique combustion method “expander bleed”, which has been used for the 2nd stage, is adopted for the 1st stage for the first time. Compared to the “two-stage combustion” of the H2A’s single-stage engine, this simplifies the mechanism at the cost of slightly lower fuel consumption. This is the key to H3’s low cost. In order to overcome the gravity of the ground and raise the aircraft in the first stage, it is necessary to have an order of magnitude ability compared to the second stage.

　In both methods, the basic mechanism is the same: the liquid hydrogen and liquid oxygen fuels are pressurized by a pump and sent to the combustion chamber, and the generated gas is discharged from the nozzle to fly the rocket. In two-stage combustion, the hydrogen is first burned in the auxiliary combustion chamber, and after the gas is pumped, it is sent to the combustion chamber, in other words, it is burned in two stages. It uses fuel without waste and has good fuel efficiency, but the control is extremely complicated.

　In 1999, the H2A’s predecessor, the H2, experienced an explosion in its two-stage combustion stage engine during flight. The H2A failed only once in 2003, but it wasn’t the engine. Together with H2B, 49 satellites have been successfully launched so far, and it can be said that the two-stage combustion technology has stabilized, but complexity and cost have become bottlenecks.

　On the other hand, in the expander bleed, hydrogen is first expanded by the heat of the combustion chamber to drive the pump. Since there is no auxiliary combustion chamber, the number of parts can be reduced by more than 20%, reducing costs and improving reliability. Moreover, there is very little risk of explosion in the event of trouble. However, the hydrogen that moves the pump is not sent to the combustion chamber, but is discharged from the nozzle (bleed) and thrown away. This makes it easier to control in exchange for a 3% sacrifice in fuel consumption.

　Development of the H3 started in 2014. Initially, the launch was targeted for 2020. However, Mr. Okada’s words, “rocket engines are monsters,” are true. During the combustion test in May 2020, when development was thought to be nearing completion, many small holes were made in the wall of the combustion chamber and the blades of the turbine were cracked. Despite overcoming these problems, in January 2010, it was postponed again due to the discovery of abnormal vibrations in the turbine. In September, he said he finally had a chance to come up with a countermeasure.

“Customer first” in people’s life, science and business

　The government calls the H2A, H3, and the small solid-fuel rocket “Epsilon” “key rockets.” It is a rocket necessary for launching various satellites, probes, and spacecraft based on government policy without relying on foreign countries. There are earth observation and positioning satellites, information gathering satellites for security, etc. H2A also worked on the familiar meteorological satellites “Himawari 8 and 9” and the asteroid probe “Hayabusa 2”. H2B carried the cargo resupply vehicle “Kounotori” of the International Space Station (ISS). The H3 will take over that role.

　Another pillar of use is business. In order to keep flagship rockets alive, it is necessary to launch them frequently and sustain related industries. H2A entered the market in 2007 by transferring launch operations from JAXA to Mitsubishi Heavy Industries. So far, it has launched five foreign satellites and probes for a fee. JAXA will launch H3 1 and 2 as a test model, but the 3rd will be transferred to the company at the earliest.

　H2A’s success rate is 97.82%, which is the highest level of reliability in the world, but it is expensive compared to overseas companies. After the development of H2A, commercial communication satellites became larger, and there was a problem that they could not meet the demand due to lack of capacity. The H3 has been developed with the aim of overcoming these problems. “We will make the rocket a customer-first with flexible services,” says Mr. Okada. In 2018, without waiting for the first launch, Mitsubishi Heavy Industries agreed to launch the H3 satellite of British mobile satellite communications giant Inmarsat.

Consumer products, automatic inspections… Pursuit of rationalization, halving costs

　In addition to the development of the LE9, H3 pursued streamlining through various innovations. As much as possible, various parts are used for consumer products such as automobiles, not for space use. In the near future, we will incorporate 3D printed parts into the LE9. In addition, the H2A booster has the same specifications as the Epsilon 1st stage, but it will be the same as the H3’s successor “Epsilon S” under development.

　Through automatic inspection of the aircraft, the control room, which was close to the launch pad, can now be placed about 3 kilometers away. The current 100-150 workers can be reduced to 30-40. Efficient production lines. It will be possible to launch in a short period of time after receiving an order, and the required interval between launches will be shortened from less than two months for H2A to about one month.

　Through a series of initiatives, the launch cost of the H2A basic type, which is said to be about 10 billion yen, will be halved to about 5 billion yen for the H3 type without a booster. In addition, even if the launch of H3 begins, H2A is planned to coexist until 2024.

The market is in serious shortage of rockets

　Japan is not the only country that has struggled with the development of large rockets. Europe’s “Ariane 6” has been affected by design changes and the corona disaster, and the combustion test has taken time, and the first flight has been delayed from 2020 to the fourth quarter of this year. At a press conference in Japan last October, Arianespace CEO Stephan Israel touched on the delays in the H3 and the U.S. Vulcan, saying, “At a scale that aims to be large and high, there will inevitably be delays. All three rockets are on the same path,” he said of the difficulty of development.

　In 2017, SpaceX, which accelerated price competition, realized the reuse of the first-stage airframe of “Falcon 9”, further consolidating its advantage. Ariane, which has pioneered the global market, boasts a deep-rooted popularity. Under these circumstances, attention will be paid to how far the H3 can penetrate the world while steadily succeeding and fulfilling the role of a flagship rocket.

　In recent years, the use of satellites has been rapidly progressing, including the “constellation” that links many satellites. On the other hand, the market is facing a severe shortage of rockets due to the fact that Russia’s aircraft cannot be used due to the invasion of Ukraine. There is an urgent need for rockets that can be used stably. If the H3’s first launch succeeds, as Mr. Okada has repeatedly said, “We will launch without a single cloud,” we will be able to strongly communicate its value to the world.