Science Report 024

Lifting the Curtain on Auroras 06

Aurora Science as Key to Understanding Earth, Universe and Who We Are

With our daily lives increasingly dependent on infrastructures existing in space, including communication satellites, it is ever more important to better understand the environment surrounding our planet. To do that, however, requires much more than researching the Earth and Sun. “Earth and planetary science” is an all-encompassing field of study, which attempts to answer such questions as, “How are planets born?” and “Where does life come from?”

Today, the availability of big data is transforming earth and planetary science -- which includes aurora science -- into a melting pot of science, breaking down all sorts of disciplinary walls, including the one that used to exist between the studies of the tropospheric and stratospheric atmosphere and the research on the upper atmosphere 50 kilometers or more above the ground.

“The research on Earth’s crust, atmosphere and oceans -- which were three separate fields -- are also becoming increasingly interconnected, as well, and will likely fuse together into one eventually,” said Ryoichi Fujii, the president of the Research Organization of Information and Systems (ROIS), Inter-University Research Institute Corporation.

So, what exactly is happening on the frontier of aurora research? How far could the new research methods take scientists in their quest to solve the mystery surrounding space and life? Dr. Fujii will give us an overview of the latest research endeavors in earth and planetary science.

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Ryoichi Fujii

Ask the Expert: Ryoichi Fujii (Research Organization of Information and Systems — ROIS)

Since 2017, Ryoichi Fujii has served as the president of the Research Organization of Information and Systems (ROIS), Inter-University Research Institute Corporation. As an expert in space physics, Dr. Fujii has a particular interest in the research of Earth’s magnetosphere and ionosphere, where auroras occur. He has worked to advance Japan’s collaboration for the European Incoherent Scatter Scientific Association (EISCAT)’s multinational radar observation program that conducts ionospheric and atmospheric measurements. Prior to his appointment to his current position at the ROIS, he has taught at Nagoya University as a professor and served as the director of the university’s Solar-Terrestrial Environment Laboratory, and then as the university’s vice president. External appointments he has had include: EISCAT Council chairperson (2003-2004); a member of the ad hoc committee on Space Science and Exploration under the Subcommittee on Space Industry, Science, and Technology of the Committee on National Space Policy, Cabinet Office of Japan (2015-). Dr. Fujii holds a doctorate degree in science from the University of Tokyo.


Geospace research could reveal universal truths

What kind of planet is the Earth?

Earth and planetary scientists try to answer the question by looking at the Earth from two different perspectives: in relation to its immediate environment, or geospace, and in relation to the entire universe.

These days, people are paying a lot of attention to the former context, as geospace is becoming an integral part of our lives on Earth.

“Space, and geospace in particular, is becoming a more important place for human activities,” Dr. Fujii said. “From weather and communication satellites to the global positioning systems (GPS), many components of the infrastructure that supports our lives are now in space. We cannot sustain the current level of human activities without relying on what we have in space.”

The need to maintain and protect these infrastructures in space is spurring research on space weather forecasting (predicting how the Earth’s environment is changing), according to Dr. Fujii.

Studying the geospace also helps us better understand the Earth in a larger context -- the context of the universe, as well.

“For example, there are times when you look at images or energy measurements of the solar system and realize similar phenomena are found in various parts of space outside the solar system. There may be the same basic principles behind all of these phenomena,” Dr. Fujii said.

“To truly understand a phenomenon, you have to be there and conduct thorough observations. But, humans can travel only so far in space. So, our observational activities become restricted to within the geospace,” he said.

Arase, a geospace exploration satellite, was launched in 2016 to make such direct observations.

“The satellite physically explores the Van Allen belts to observe interactions between plasma waves and high-energy particles. It’s the world’s first observation of its kind,” Dr. Fujii said.

Eight planets: Earth is a lot like, and so different from, its neighbors

Commonalities and differences that exist among the eight planets of the solar system can also provide important clues in understanding space in a larger scale.

All eight planets differ in size. Venus has very few magnetic fields. Mercury has no atmosphere. Large auroras appear only in the skies of Jupiter, Mars and Earth -- the three planets that are in the direct path of solar winds and have both magnetic fields and atmosphere.

“These planetary features appear in pairs, and there are four different pairs. In other words, the geospace planets are very diverse,” Dr. Fujii said.

“However, we suspect there may be a common thread that runs through these differences. These features may share a physical process through which they occur” Dr. Fujii said. “If we understand the process through which the solar system’s phenomena develops, that might also apply to phenomena observed in other galaxies -- or could even explain the process of nuclear fusion on Earth. In that sense, earth and planetary science is a very important science.”

In order to understand different phenomena, earth and planetary science researchers have traditionally used the equations of electromagnetism, kinetics, and fluid dynamics to derive how physical quantities -- such as velocity, mass, and electric and magnetic fields -- are spatially distributed and how they change with time. But because it’s impossible to elucidate complex natural phenomena by just using first principles and theories, they are now using simulations that are based on observations, as well as graphical modeling, as their research tools. Combining all these methods creates “a three-pronged approach” to their research.

“People say things like, ‘We see an aurora every night,’ and you’d think it really comes back nightly. But in reality, no natural phenomenon ever repeats itself in the exact same way,” Dr. Fujii said. “It’s important to observe and try to understand the fine details without over-simplifying things. At the same time, we need to try to think what all those differences have in common.”

To the right of the photo is an omnidirectional film camera once used for observations. “I used to calibrate this all night long in the Antarctic to keep records of auroras,” said Dr. Fujii, who served in the 23rd and 32nd Japanese Antarctic Research Expedition as a member of the winter expedition teams. Researchers nowadays are increasingly using the machine learning technology to sift through enormous amounts of imagery data and identify phenomena on which they want to conduct research.

Science at crossroad: Changing research methods

In today’s earth and planetary studies, a “scientific method” can mean more than one thing. For example, in order to understand the mechanism of correlation between solar cycles and Earth’s climate, one could take the traditional scientific approach by relying on data and theories to determine the process of physical changes occuring in the Sun -- such as the solar dynamo, flares and plasma motions --and in the solar earth system --such as energy conversions and propagations.

“Or, they could take advantage of the rapidly improving capabilities of artificial intelligence (AI),” Dr. Fujii said. “Machine learning has made it possible for us to obtain a colossal amount of data. We can feed that data to a machine to make it learn, so its accuracy in forecasting will improve.”

There are many ongoing projects aimed at identifying the solar-earth correlation mechanism, because this is the last major mystery left to be solved in solar research.

The Sun’s activity and energy control pretty much everything in the physical space being studied in earth and planetary science. Scientists already know a lot about the Sun, including the details of the distribution of magnetic fields on the Sun’s surface, how they change with time and how much energy they have. The Sun is “the most precisely understood celestial body of all in terms of its physical quantity,” as Dr. Fujii puts it. However, researchers still understand very little about the mechanism behind the correlations between the short- and long-term cyclical changes and the changes in the Earth’s environment.

Ongoing research endeavors on this topic include novel ones, such as a project to determine the aforementioned correlations through an analysis of an over two-thousand-year-old tree’s rings.

“If such research projects enable us to understand how the solar dynamo (magnetic field formation) works, we may then be able to predict whether the Earth will enter another Ice Age or continue to warm up. That would make a big difference for our human species,” Dr. Fujii said.

“I tend to want to understand what basic principles are behind such a mechanism,” Dr. Fujii said about his choice between the traditional and new research methods. “But, machine learning is a research field that has advanced tremendously in recent years, and there are those who say we should make use of this science to the best of our ability. Given machine learning’s social impact, I believe it’s also important to heed the demand,” Dr. Fujii said.

Data science makes it possible to elucidate complex phenomena by analyzing massive amounts of data, and it’s a growing science trend to incorporate data science into research.

“It is most important to connect the traditional and new methods,” Dr. Fujii said. “I believe that will lead to further advancement of data science.”

‘Open data’ and ‘open science’ for new discoveries

Having massive amounts of data and being able to effectively analyze it are critical to the success of In earth and planetary science research that deals with complex natural phenomena. In other words, promoting data collection and the advancement of data science is of key importance to furthering earth and planetary science research.

For geospace and aurora research, Dr. Fujii has thought it would be particularly helpful to obtain three-dimensional, high-resolution measurements of the density, temperature and movements of the ionospheric atmosphere. This was the reason why since the 1970s, Dr. Fujii has tirelessly spearheaded Team Japan’s efforts in the European Incoherent Scatter Scientific Association (EISCAT)’s multinational radar observation program.

The National Institute of Polar Research (NIPR) joined the EISCAT in 1996 and has since represented Team Japan on EISCAT. The EISCAT is currently working to implement “EISCAT-3D,” a project in which radars in three different locations in northern Europe will be used to take three-dimensional, high-resolution measurements of the atmospheric density, temperature and movements, among others, in the upper and middle atmosphere.

“These radars use cutting-edge phased-array systems, which Japan has greatly contributed to develop. Phased-array radars shoot a beam up in the sky and steer it extremely fast, so it can detect things in the sky, their spatial distributions and how they change with time. There are regions of the atmosphere where ionosphere and magnetosphere interact with each other in a complex manner. The EISCAT radars will be used to observe these regions, as well, and so it will be very interesting,” Dr. Fujii said. “The systems’ resolutions are so high that they have the ability to capture tiny objects very clearly, including tracking a meteorite’s fall toward Earth.”

EISCAT_3D is scheduled to go online for full operation in 2021.

In the meantime, the growing use of “open data” and the “open science” movement are helping advance data science.

“How we maintain data and make use of it, including data analysis, has changed a lot in recent years. We are now in a new phase in the data era,” Dr. Fujii said. “The research institutes that make up the Research Organization of Information and Systems (ROIS) include the National Institute of Polar Research (NIPR), as well as the Institute of Mathematical Statistics (IMS), which conducts research on ‘data fusion’ for effective integrations of simulations with data. As an Inter-University Research Institute Corporation, we are committed to support and collaborate with these and all other organizations, including universities, for data compilation and sharing. We believe, by continuing to work together, we could make extraordinary discoveries in science.”

The omnidirectional film camera and this antique vehicle used for the Japanese Antarctic Research Expedition are both exhibited at the NIRP’s Polar Science Museum (Tachikawa City, Tokyo), which is also home to the Aurora Theater.

Interviewer: Rue Ikeya
Photographs: Yuji Iijima unless noted otherwise
Released on: Jan. 10, 2020 (The Japanese version released on Jan. 10, 2019)

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