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An aurora is a message from the Sun

--- What questions are you particularly interested in right now?

Aurora curtain (courtesy: Zoltan Kenwell/NASA)
Aurora curtain (courtesy: Zoltan Kenwell/NASA)

People like aurorae because they are beautiful to our eyes, but they actually contain a lot of messages from the Sun, because the Sun is their home. I would like to decipher these messages as much as possible.

Solar wind plasma enters the magnetosphere, and something directs it to flow over the polar regions. It is thought to have something to do with the instabilities of the plasma in the magnetosphere. But what causes plasma instabilities? What makes plasma flow over the polar regions? How does an aurora explosion occur? Why do aurorae appear to be moving? What I want to know changes endlessly – it’s like a chain reaction.

--- Did you say that aurorae appear to be moving? You mean, they are not really moving?

Coronal aurora (courtesy: Nanook Aurora Tours/Yoshifumi Otsuka)
Coronal aurora (courtesy: Nanook Aurora Tours/Yoshifumi Otsuka)

No, they are not. They look like they are moving in the same way that neon or electronic signs look like they’re moving. Neon lights aren’t moving, but they look like they are because the bulbs light up in sequence. As a matter of fact, it is the same with an aurora. An order for which part of the sky should glow, and how, is issued in space. When the aurora curtain starts waving and reverses direction, the audience thinks that the direction of the wind has shifted. But it’s not because of wind. It’s still a mystery to us why an aurora can seem to move in such a bewitching, unique way.

Japan to lead the world with its own satellite

--- JAXA has an aurora observation satellite, AKEBONO, and a magnetospheric observation satellite, GEOTAIL. What is your impression of these satellites?

Aurora observed by the AKEBONO satellite
Aurora observed by the AKEBONO satellite

In addition to observing plasma particles, which create aurorae and geomagnetic storms, AKEBONO has discovered ions flowing out from the Earth’s polar ionosphere. While electrons that generate aurorae are accelerated in the direction of the Earth, conversely ions escape upward from the upper atmosphere. I think that this is a world-class achievement in the area of ion outflow observations. Although the satellite was launched more than 20 years ago and its aurora imager has deteriorated, it is still continuing to observe magnetospheric particles.

GEOTAIL has achieved great results in its observation of the tail of the Earth’s magnetosphere. Plasma particles, which create aurorae, gather at the center of the magnetospheric tail, and GEOTAIL has directly observed that region. This is a little technical, but it was confirmed that a physical process called magnetic reconnection plays a key role in the acceleration of auroral particles. I remember the mission very well because a prestigious U.S. academic periodical, the Journal of Geophysical Research, published many Japanese papers about results obtained by GEOTAIL. Besides, the pre-launch management and planning was impressive, too.

Prof. Atsuhiro Nishida, the former Director General of JAXA’s Institute of Space and Astronautical Science, was the project manager. The project progressed under the concept of “all Japan” from its beginning, gathering opinions about what to observe with GEOTAIL, what could be discovered with what data, etc.

Although I am not a hardware person, I attended the meetings, too. The satellite was launched after much preparation, so it is no surprise that people’s motivation was very high and many papers were published. Japan led the project, which also involved the U.S. and Europe. The mission is highly regarded in the world in this respect, too.

--- What would you like to see from JAXA in the future?

ERG (Exploration of energization and Radiation in Geospace) satellite
ERG (Exploration of energization and Radiation in Geospace) satellite

Japan has earned a great reputation in the world for the results of solar observation satellites, YOHKOH, launched in 1991, and HINODE, launched in 2006. And now, there seem to be active discussions about the next satellite after HINODE. In the U.S., there is an observatory for measuring the polar magnetic fields of the Sun, but they are observed from the side. I imagine that there are many technical challenges but I hope for the realization of a satellite, which can look at the poles from directly above them someday.

Aurorae are phenomena that occur in geospace, the near-Earth space environment. Geospace is a compound word, consisting of “geo,” meaning “earth,” and “space.” This region is filled with solar wind plasma. JAXA is planning to launch the exploration of Energization and Radiation in Geospace (ERG) satellite around 2015 to observe the radiation belt, which has a large volume of highly charged particles. This also has a lot to do with aurorae, so I am very much looking forward to the data that will be collected. I really hope this mission goes well.

These satellite missions are progressing under the leadership of young scientists. I hope that, like Prof. Nishida of the GEOTAIL project did, they will be able to develop teams capable enough to lead the world. It’s important to collaborate with people overseas, but I would like Japan to lead the world anyhow. In the world of research, there is both competition and collaboration. It is no good if you are always fighting, but you cannot be too friendly because otherwise they will take everything from you. For scientists, papers are the end game, so I would like to see many papers by Japanese researchers get published.

Break the culture of silence and challenge the world!

--- What is your impression of today’s young scientists?

There are many competent scientists, but compared to the past, I am under the impression that they are less ambitious overall. I know what things were like when GEOTAIL was leading the world, so in comparison, I feel that today they are relatively low key. According to a recent announcement by the Ministry of Education, Culture, Sports, Science and Technology of Japan, these days papers written by the Japanese are less frequently referenced and less influential.

--- What would you like to say to these scientists?

I want them to write many papers that shine and can survive for the next 100 years. In other words, I am hoping that they will have high aspirations to conduct research. To accomplish great things, they need to be cosmopolitan and abandon the Japanese culture of silence. In Japan, if you are straightforward in expressing your opinion, you are criticized for being impudent. There is even an expression, “the aesthetics of silence.” However, this does not work in the international community. If you keep silent outside Japan, people will think that you know nothing or that you are not thinking anything.

What I learned in the U.S. is that scientists with different nationalities exchange opinions openly, as they respect each other. In scientific discussions, you cannot be reserved. If you cannot understand the speaker’s English, it may be good if some Japanese can be bold enough to complain that their English is bad. (laugh)

--- Finally, could you give us a message for children?

When studying science, you should not start with memorization. It doesn’t do any good to memorize formulas without understanding what they mean. Dinosaurs, bugs or plants – it doesn’t matter what it is, but it’s important to find something you like, and to let yourself be carried away by it. For example, you can be impressed by the beauty or the dynamism of aurorae. I think that this should be how people are introduced to science. I hope that children, who are the bearers of the future, find something they can be passionate about.

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