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The Moment HAYABUSA Became a Meteor Junichi Watanabe Member of the HAYABUSA Atmospheric Re-entry Observation Team at the National Astronomical Observatory of Japan

Impressive spectacle in Australia

Q. What was the purpose of HAYABUSA’s atmospheric re-entry observation team? Why did you want to witness HAYABUSA’s return to Earth?

HAYABUSA as a meteor (Courtesy of KAGUYA)
HAYABUSA as a meteor (Courtesy of KAGUYA)

HAYABUSA’s atmospheric re-entry observation team was organized to observe the atmospheric re-entry of the Asteroid Explorer HAYABUSA prior to its touchdown in Australia. The team of seven consisted mainly of members of the National Astronomical Observatory of Japan (NAOJ) and included a professional photographer.
The reason we wanted to observe HAYABUSA’s return to Earth was its connection to NAOJ’s research on meteors, which we usually observe from the ground. Meteors are natural phenomena in which space-dust particles enter Earth’s atmosphere, heat up due to friction with the atmosphere, and become luminous. However, we don’t know very much about the composition of this falling dust, so we can only guess what kind of materials are glowing and to what degree of brightness. On the other hand, details about HAYABUSA, including the composition and mass of the explorer and its re-entry capsule, were well-known. I thought that if we could measure how HAYABUSA released light during its re-entry into the atmosphere, we could find some clues to the mystery of meteors. In other words, HAYABUSA was an artificial meteor. Since it was a Japanese spacecraft that was going to become an artificial meteor, we couldn’t miss that chance. I wanted to see it with my own eyes, and so I organized an observation team.

Q. How did HAYABUSA’s capsule re-enter the atmosphere on June 13, 2010. What were your thoughts after witnessing this event?

The last of HAYABUSA. The dot to the lower left of the fireball is the capsule. (Courtesy of Yutaka Iijima)
The last of HAYABUSA. The dot to the lower left of the fireball is the capsule. (Courtesy of Yutaka Iijima)

We waited for HAYABUSA’s return near the desert where the capsule would land, on the outskirts of Coober Pedy, in South-Central Australia. According to the official schedule, I was to announce the countdown information: "the current time is such and such, it’s so many minutes before atmospheric re-entry." I think the hearts of everyone waiting for HAYABUSA were united as one.
HAYABUSA was scheduled to separate from the re-entry capsule at 19:15 Japan time, and make an atmospheric re-entry three hours later, together with the capsule. While we were impatiently waiting for the big moment, a dot of light started to appear in the western sky almost exactly as scheduled. This had to be HAYABUSA. My eyes were stuck on that light, which had a tail just like a meteor. It became brighter and brighter, and lit up the clouds around it while traveling across the Milky Way. A small dot moving ahead of it was the capsule, and the main body of the explorer was chasing after it while releasing a bright light. Soon, the main body of the explorer couldn’t tolerate the heat of the atmospheric re-entry, and broke into pieces and burned up. At the same time, the light that seemed to be coming from the capsule disappeared into the darkness of the night sky. The time span from the first appearance of the light to when it vanished was very short, around 40 seconds, but it was very exciting.
The weather that day was excellent, and we were able to acquire good data and images of the artificial meteor HAYABUSA. I thought that was really lucky. I felt so glad that I had come to Australia to witness the event. In addition, based on information supplied by JAXA, we had predicted the direction from which HAYABUSA would fall, and the light actually appeared at almost the exact location we had predicted, so once again I was impressed by the explorer’s orbit control technology. I think it was an amazing experience for me to witness the last day of HAYABUSA’s life at the end of its 7-year-long space journey.

HAYABUSA sowed seeds of curiosity and fostered confidence

Q. Why do you think HAYABUSA attracted so much attention from the general public?

Asteroid explorer HAYABUSA (Courtesy of Akihiro Ikeshita)
Asteroid explorer HAYABUSA (Courtesy of Akihiro Ikeshita)

To tell the truth, I honestly don’t understand why. In the past, the world was impressed when Apollo 13 returned safely to Earth after encountering system trouble, but that was a manned mission that involved the lives of its crew, so the interest was not surprising. But HAYABUSA was an unmanned explorer. Many people got emotionally involved in its mission, and I was surprised at the strong feelings the explorer generated. Probably, the situation reflected the spirit of the Japanese people, with HAYABUSA’s miraculous revival and its seven-year journey through space with wounds all over its body, overcoming numerous crises.
There were so many people who wanted to support HAYABUSA after learning about it on the news, but this couldn’t have happened if you’d planned it. People were simply charmed by HAYABUSA - there was no pressure to support it - and that charm created a boom in interest. The way planetariums and the media rode the crest of this wave and produced shows about HAYABUSA created a large synergetic effect.
Based on this experience, one may wonder why Japan’s first ever Mars explorer, NOZOMI, which was launched in 1988, didn’t gain that much attention. NOZOMI managed to approach Mars even though it had various troubles on its way there. But in the end, we couldn’t inject it into the Martian orbit and the mission ended in failure. I wonder why people weren’t that interested in NOZOMI at the time. I suppose HAYABUSA’s special feature of a return to Earth greatly affected people.

Q. How do you think we should utilize the popularity of HAYABUSA?

ALMA Telescope under construction in Chile. (Courtesy of NAOJ)
ALMA Telescope under construction in Chile. (Courtesy of NAOJ)

HAYABUSA’s achievement gave Japanese children great confidence in our space technology. When Japanese athletes win medals at the Olympic Games, people feel very proud of them. The same way, HAYABUSA made young people impressed by Japanese science and technology, and gave them something to be very proud of. I’m pretty sure they felt "Japan is awesome!" Once they start thinking like that, the next feeling they probably have is, "Let’s try that ourselves." I think the best way to use HAYABUSA’s popularity is to encourage such thinking in young people, so that they develop an interest in something.
It is a very important task for us to raise children who are going to be responsible for the future of Japan. But with today’s stable social systems and hyper-networked world, human beings start to see stability as a primary value. It may even happen that more young people will think that all they need to do is follow the roads that have already been paved. If this happens, there will be fewer people wanting to do creative work. To prevent this attitude from taking root, we cannot ignore education. If kids think, "We’d like to do that, too," or, "We may be able to do that," I think things are going to move in the right direction. In that sense, HAYABUSA was very effective, so before this sensation disappears, I would like to create the next "space star."
For example, there are two "stars" at NAOJ: the Subaru Telescope and the ALMA (Atacama Large Millimeter/submillimeter Array) Telescope. Besides having an open house every year, we carry out various kinds of public activities, such as stargazing parties, a public screening at a 4D movie theater, junior astronomy classes during summer holidays, etc. On these occasions, we talk about a "star" such as the Subaru Telescope, but we try to emphasize the interesting, fun and mysterious parts of astronomy. Specifically, we make sure to tell guests about something that we haven’t learned yet. If we just tell them about the results - things we already understand - people might think, "Since all these things are known, there is nothing else we need to do." When there are unknowns, people think they’d like to study them as well, right? Similarly, there are many "stars" in other fields, such as science and medicine, so if we all use these "stars," I think we can help solve the problem of children turning off science. I think our top priority is to make people feel amazed by and interested in science.

  
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