Space Battleship Yamato has had an influence on real things actually happening in space exploration, and thanks to an ongoing NHK series titled Project X ~ Challengers we learned of a Yamato connection to the real-life Hayabusa asteroid sample return mission operated by JAXA from 2003-2010.

Asteroid probe Hayabusa‘s miraculous return to Earth

By ksagiksagi

Published at the Cultural Document Fan Club blog on September 30. See the original post here.

The author comments on documentary programming; this piece was published in response to an episode of an NHK series titled Project X ~ Challengers that focused on the Hayabusa mission.

The long-awaited appearance of Hayabusa

This time, Hayabusa appears. Well, if you think about it, this is the only project in Japan since the Heisei era that has been a spectacular success, so it’s easy to imagine that this is the main focus of the series.

In 1981, when America was launching the space shuttle, Japan was limited to launching unmanned unmanned rockets. Junichiro Kawaguchi of the Institute of Space and Astronautical Science (the predecessor of JAXA) was frustrated by this situation. In order for Japan to make its presence felt, Kawaguchi requested a joint study session with NASA and presented a plan for an asteroid rendezvous.

It is difficult to control a probe when approaching and observing an asteroid with low gravity. He proposed to develop the technology together, but at the eighth study session, NASA said they would do it alone. Feeling that his idea had been stolen, Kawaguchi declared, “In that case, we will do a sample return.”

Development of a new engine holds the key

After returning to Japan, Kawaguchi gathered members and began to consider the matter. The biggest problem was the engine. To get through the journey, a round trip of at least four years, an engine with good fuel efficiency, different from conventional chemical engines, was needed.

The key person in solving the problem was Hitoshi Kuninaka. He was researching a new engine called an ion engine. This engine was ten times more fuel-efficient than conventional engines, but was not yet ready for long-term operation in space.

In 1996, the government officially provided funding and the project started. More than 500 people, including those from private companies, were involved in development. Kawaguchi wanted the engine to last 14,000 hours. However, Kuninaka and his team only managed to achieve 150 hours.

The problem was that the internal parts of the device, which generates negative electricity when it exceeds 150 hours, would start to melt. After more than ten attempts at creating various prototypes, they finally achieved a structure that would not melt. They conducted durability tests and finally achieved the goal of 18,000 hours.

In 2003, the asteroid probe that was a symbol of Japan’s prestige was completed.

The landing was successful, but troubles continued

In May 2003, the probe was launched and named Hayabusa. An operations team of 30 people remotely controlled it. Two years and four months after launch, Hayabusa finally sent back photos of its target, Itokawa. But from here on, the biggest mission was to bring back the sand.

When it landed on Itokawa, it was supposed to fire a bullet into the surface and collect sand in a capsule. Finally, the landing took place. But then something went wrong. The altimeter went negative. Kawaguchi gave an emergency command to raise the craft. The question was whether to make a second attempt. If it failed, there was a possibility that it would not be able to return to Earth. However, since the bullet had not yet been fired, Kawaguchi did not have the option of returning home.

The second landing took place and was successful. The bullet was fired and the sample was collected. It soon took off, but communication with Hayabusa was lost. It seemed that the attitude control device was damaged during the landing, and the solar panels could not be pointed toward the sun, causing a loss of power. There had never been an example of a probe being reacquired in such conditions. The crew felt hopeless.

A month after communication was lost, the operations team continued to search for Hayabusa. Kawaguchi was searching for the possibility that communication might be restored, even for a moment. He thought there was still a chance. Then, two months after communication was lost, a peak appeared in the waveform on a monitor in the control room. A command was sent and Hayabusa gradually regained its functions. Finally, a year later, Hayabusa took off for Earth.

However, with six months to go, the engine began to malfunction. It was immediately clear that the engine’s lifespan had come to an end. Up to this point, excessive strain had been placed on the engine. Most of the four ion engines had lost their function.

Kawaguchi felt hopeless, but Kuninaka had one last move. He had secretly installed a circuit for cross operation, combining the remaining equipment of the surviving engines. There had been no examples of its operation in space, but this would bring the engines back to life.

In June 2010, Hayabusa returned to Earth, detached its capsule, returned to the atmosphere and burned up. Before that, Hayabusa sent back photos of the Earth. The capsule then descended into the Australian desert and was safely retrieved.

As you can see, this was a major project that truly demonstrated the reputation of Japan, a country built on technology, and it was a perfect example of success thanks to the careful preparation and bold decisions of the researchers. Even in America, where space development originates, it is strongly criticized as a “money pit.” So if Japan had failed in this project, there was a high possibility that we would have given up on planetary exploration. This project can be described as a gamble for the fate of the space development industry.

Key points for busy people

– Japan was lagging far behind America in space exploration technology. Junichiro Kawaguchi of the Institute of Space and Astronautical Science (the predecessor of JAXA) approached NASA about joint technology development for the asteroid rendezvous, but NASA decided to develop it alone. Furious, he declared that Japan would achieve sample return.

– The biggest problem was the development of a fuel-efficient engine that could be operated in a round trip that took at least four years. The key was the ion engine that Hitoshi Kuninaka had been researching, but its durability was still far from the target.

– The project officially began in 1996, and Kuninaka and his team worked hard to improve the engine. They somehow managed to reach the target durability. And so, in 2003, Hayabusa was launched.

– Two years and four months after launch, it finally reached Itokawa and attempted to land, but an anomaly occurred during the first landing, and they had to try again. The second attempt was successful, but communication with Hayabusa was subsequently cut off.

– The operations team continued to desperately search for Hayabusa, and after two months they finally succeed in restoring communication. They gradually restored its functions, and one year later Hayabusa finally departed for Earth.

– However, six months before reaching Earth, the engine experienced trouble. At this point, Kuninaka performed a cross operation, combining the parts of several engines that were not broken, and Hayabusa‘s engine started again. Hayabusa succeeds in delivering the sample capsule to Earth.

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