It's truly a miracle, and soil is a piece of a star, containing the DNA of all life. The formation of clay minerals is also evidence of crustal movement, and progressing sedimentation in this area led to the appearance of a huge freshwater lake (Lake Tokai) about 5 to 10 million years ago. The Mino area was at the bottom of this lake, and magma slowly cooled and solidified in the volcano to form granite, which became weathered granite through weathering. The granite was then carried by water, becoming finer and finer, and after repeated dissolution by water, it flowed into Lake Tokai and produced a large amount of clay minerals because the larger the lake, the better the clay minerals. They matured by being acted on by bacteria in a deep underground location deprived of oxygen over a tremendous period of time, giving them their plasticity. The character of the pottery changes depending on what happened during the maturing period. If the clay minerals become iron-laden, you cannot fire pure white pottery.

Speaking of crustal movement and weathering, the Moon doesn't have an atmosphere or liquid water, so it doesn't have active weathering and erosion like on the Earth. In the distant past, though, there were active changes such as volcanic activity that caused lava to erupt and cover part of the surface.

Is the lava inside the Moon still alive?

We don't know, but we as scientists all want to know. The Moon is small, about a quarter the size of the Earth, so it has few internal heat sources, and it was thought that the lava had cooled completely and died. Recently, however, a very young volcano, younger than previously known, was discovered, and it is said that it may still be alive.

So you're saying there may be a volcano still active on the Moon?

Yes, that's right.

You don't have any photos showing the actual point where the volcano erupted, do you?

There are photos of lava flows and other such features. Most craters on the Moon are thought to have been carved out by meteorites or small celestial bodies that hit the surface at a very high speed. In very large craters, a hole opens in the crust, and basaltic magma erupts from it and fills the crater. Basalt contains a lot of dark iron and magnesium, so the area where the lava cooled and solidified looks black and shadowy, meaning there are traces of the flow in such areas.

And the smoke?

There's no smoke now because the lava is already cold and hardened.

I see. So the magma eruption you mentioned earlier was quite a long time ago.

Yes. We use a method known as "crater chronology" to estimate how old or new volcanic activity is. A certain number of meteorites are thought to fall fairly evenly across the Moon, so the more craters per unit area, the older the location.

Why don't meteorites rain down on the Earth?

Because they burn up in the atmosphere. What we see as shooting stars are in fact meteorites and dust that have fallen to Earth.

The Earth is saved by having an atmosphere, isn't it?

That's right. The Moon, on the other hand, has no atmosphere, but it's subject to weathering due to the large temperature difference between the times it's exposed to sunlight and the times it's not, and to erosion due to the impact of meteorites and dust. The surface of the Moon is also exposed to solar winds, and in this way the surface of the Moon is broken into small pieces and covered with fine sand (regolith). Since no wind blows on the Moon, the footprints made by the Apollo astronauts on the Moon about 60 years ago are still visible and the American flag is still standing on the lunar surface. The interesting thing is that they were not originally planning to put the Stars and Stripes on the Moon, but the idea eventually came to them and a flag they bought at a nearby department store was taken to the Moon.

I saw on TV the moment when Neil Armstrong put the American flag on the Moon.

The Moon is bathed in very strong ultraviolet rays, so the Stars and Stripes may be completely white and tattered by now. But we know from orbiter scans that the flag is still standing.

That's surprising. Come to think of it, the Moon is said to be receding from the Earth by three centimeters per year. What's the reason for this?

It's because the Earth's oceans are passing energy to the Moon. We have tides, right? They're caused by the gravitational pull of the Moon pulling on the Earth's ocean water. The Moon orbits slower than the Earth rotates. That means the Moon pulls on the Earth and is trying to move faster. That's why the Earth's rotation is slowing down. In fact, when the Earth was first created, the day was shorter than it is now but the Moon's pull caused the Earth to lose energy so the day is now 24 hours long. In other words, as the Earth's rotation slows down, the Moon's orbit grows larger, resulting in a greater distance between the Moon and the Earth.

So the Moon will eventually leave the Earth's gravitational sphere.

It will if this energy transfer continues far into the future

Without the tides, the Earth's rotational speed would still be the same as it was in the past and the Earth's environment would be different, so the existence of the Moon is a key factor in making the Earth what it is. As for the influence of the Moon in our lives besides the tides, it is said that wood cut at the new moon will last longer.

My question is, can ilmenite be used as a binder for clay (ceramic clay)? Because parts of the lunar maria (lunar plains covered with dark-colored basalt) contain a lot of ilmenite.

Ilmenite can indeed be used as a binding agent.

Have you actually used it?

Titanium is used in new ceramics, for example. Titanium is frequently used in glazes (glassy films covering the surface of ceramics). Titanium is also often used in sanitary ware such as toilet bowls and wash basins because of its ability to maintain a high level of hygiene for a long time.

I see.

Irradiating titanium with ultraviolet rays (photocatalysis) decomposes various organic substances. That is what makes it effective in removing stains and odors, as well as sterilizing and disinfecting.

You also know whether there are metals on the Moon through orbiter scans, don't you? Do you have any kind of distribution map of metals?

Yes, we do.

With that, we could predict the color of the pottery.

Really? (laughs)

The process of transforming glazed clay into pottery by applying heat is called honyaki (glost firing) and the firing temperature for this is about 1,200 to 1,300 degrees Celsius. What color will the clay come out if it is fired in the vacuum of the Moon with no oxygen? If we know the elements, I think we can make predictions. This one would be green, that one would be pink, and so on. Although open flames couldn't be used for firing, how about inserting a satellite into lunar orbit equipped with a concave mirror and a solar tracker and then creating a heating element (furnace) by concentrating sunlight to fire pottery in the furnace?

So the colors of the pottery that we usually have at hand are the colors produced because of the oxygen in the Earth's environment.

That's right. If you make pottery on the Moon, the color will be different. That's because there is no oxygen, so the metal crystallizes as is.

And you also said that the color might be more vivid if the pottery were fired on the Moon.

Yes, because the true color of the metal will come out. It might appear rainbow-colored or even resemble Yohentenmoku (a karamono tea bowl designated as a national treasure). If elements such as molybdenum, tungsten, and yttrium are present on the Moon, beautiful crystals would surely proliferate and the pottery would become rainbow-colored. It would be like the Andromeda Galaxy spreading out in space. The Moon is a large celestial body, so these elements could be present.

So you could say that oxygen actually interferes with making pottery in the Earth's environment.

It would be interesting to visualize that for the entire Moon.

Quite interesting. It would be nice if such a project could be launched.

It could be a new art form. Even though pottery is an ancient technology, I have never heard of any scientist at NASA or ESA (European Space Agency) having any association with such technology. It's a fusion of ancient and cutting-edge technology.

It's a dream. As a first step, I'd like to blend lunar minerals and metals into clay and glaze them, and make pottery in the Earth's environment first.

Your heritage as a ceramic clay merchant goes back for generations, doesn't it?

Yes. If you unravel the chronology, the first generation started an inn back in 1839. Later, in the Meiji era (1868-1912), the tenth generation built a waterway to turn a waterwheel and set up a ceramic clay shop. I am the fourth generation to run a clay shop, and ceramic clay has been all around me since I was a toddler. I grew up in that kind of environment, so I have always felt that there was some kind of fate that I could not escape. Even so, I did give up the business once when I was young.

What did you do then?

I started making pottery. After that, though, I came back to clay, so now my work involves both clay and pottery. It's because I once left the clay business that I can appreciate both.

I see. While it's true that clay is your business, talking to you gives me the impression that you know quite a bit about pottery. The pottery samples you showed me featured quite a wide variation.

I came to Kaneri Touryo looking for clay but, before I knew it, I was consulting with them about pottery. There are many such potters. We have quite a few people who tell us, "I want to make new pottery," or "I've hit a wall and want to rethink things from the clay", and in such cases I ask them to bring in some of their own pottery.

Why is that?

It's because pottery contains something unique to the person who made it. This lies in the realm of the unconscious, so the person is not aware of it.

So what you really want to do shows up in your pottery?

It does. I ask people "Why did you get into pottery?" and then compare this original aim with the pottery in front of them. Many people have lost sight of their own pottery so I try together with them to draw it out, seeking to extract the essence of the pottery they should be holding in their hands at that moment. That takes a lot of energy, though, and as a result I can no longer make my own pottery. Since I still have the desire to create, I make my own art works out of stone or dry wood to enjoy day-to-day around the studio. I think that directing my energy toward pottery and the like in this way ultimately gives me comfort. What are you looking for as a scientist?

I want to know what I don't know. I think that's the desire that has kept me studying the Moon. There's absolutely no way I could completely understand it, but I'm getting closer to what I want to know with every bit of research that I do. I guess I enjoy that feeling.

There must be some aspects of that you are doing unconsciously.

Certainly there are times in my research when it occurs to me that it might be interesting to dig deeper into something, and I may be doing this unconsciously. Science begins with a hypothesis. You may think something works in a certain way so your hypothesis must be right, but continuing to verify your hypothesis until everyone agrees that it's correct is a very difficult thing. The scientists around you will seek to verify your hypothesis with a critical eye, and in some cases they may insist you're wrong. The scientist who first constructs a hypothesis and continues to substantiate it in the face of these headwinds will, for example, go on to win a Nobel Prize. It's this type of tough scientist who ushers in a new era, but I myself am not that type. I'm more the type of scientist who simply wants to create something that will please everyone.

What kinds of things do you actually make?

We are using lunar data to create a global map of the lunar surface. In making this map, we use images of the Moon taken from various angles by JAXA's lunar orbiter Kaguya (no longer in operation) and the US lunar orbiter LRO, but the incident angles of sunlight in these images differ. We correct the images so that they appear to be illuminated from the same direction, a very challenging but interesting task. We use this difficulty to our advantage by accumulating images of the Moon from various angles to study how the light reflects in specific locations, which proves useful in geological analyses of the Moon.

What's the technical term for that?

It's called photometric correction. For example, we use the phase angle that refers to the angle between the Sun, the observed object, and the observer. In this case, the observed object is the Moon. When we measure the spectra (light of various wavelengths) of rocks in the laboratory, the standard phase angle is 30 degrees. In other words, when we look at the Moon corrected to 30 degrees, we can finally see it on the same basis as measured on the Earth. However, in some places - the Moon's polar regions, for example - it's rarely 30 degrees.

It might take me quite some time to understand something this difficult (laughs), but you're saying that when the global map of the Moon you are making is completed, it will be like the world map that we usually see.

Yes, that's what we're trying to achieve.