JAXA Japan Aerospace Exploration Agency

Q. What specifically impressed you with respect to HAYABUSA?

Asteroid Itokawa

Asteroid Eros (Courtesy of NASA/JPL/JHUAPL)

That it showed us the true shape of the asteroid Itokawa. When I saw the pictures of Itokawa captured by HAYABUSA, I was astonished. HAYABUSA captured an image of the asteroid that had never been seen before. Since I am a planetary scientist, I thought this mission was a 100-percent success when HAYABUSA reached the asteroid and transmitted images from there.
Before this, the United States had explored several asteroids more than 10 kilometers in diameter, and all of them were covered with craters. Hence, even though Itokawa is a small asteroid that only measures 500 meters in length, it was thought that its surface was also covered with craters. But in fact, not many craters were seen on the surface of Itokawa, and it appeared to be very rocky. We also learned that Itokawa’s density is very small and its interior is porous. The world was astonished by HAYABUSA’s achievement, and Japan’s reputation in the space field received a boost. HAYABUSA’s achievements were introduced in a special edition of the world-famous American magazine Science. I think this was probably the first time ever the achievements of a Japanese explorer were documented in this magazine; even more so, even before the mission was complete.
Itokawa showed a face nobody had ever imagined, and through this I actually once again realized the importance of asteroid exploration. You can make as many predictions as you like based upon past data, but you cannot really find out the truth unless you actually go there. HAYABUSA was an explorer for the purpose of developing engineering technology, but it archived excellent scientific results as well.

Q. What are your hopes for the future of Japanese space science?

The ratio of Japan’s space science budget to its national budget is one tenth that of the United States. Investment in order to try to become a world leader in science and technology is more focused on the fields of medicine and biotechnology, which can achieve more pragmatic results in a short time span. Japan today is more materialistic, and its definition of culture is very narrow. But I think science is culture. In Western countries, there are restaurants and cafés in science museums, and adults go to science museums to enjoy themselves just like they go to art museums and concerts. In Japan, on the other hand, in most cases parents take their children to science museums to study, right? I don’t think that’s good. I think it’s important for us to become rich not only economically, but also spiritually. In this sense, I think things like space exploration and astronomical observations are "culture," based on our intellectual curiosity. I hope that Japan recognizes these aspects of space science as culture, and comes to admire them.

Q. What do you think about the idea of a successor explorer to HAYABUSA?

Asteroid explorer HAYABUSA 2 (courtesy: Akihiro Ikeshita)

I think HAYABUSA was just the start, so I’d love to see the launch of HAYABUSA-2, with improved performance. Asteroids are classified into several types, depending on their spectrum of sunlight reflection. Asteroid Itokawa is an S-type. In the HAYABUSA-2 mission currently being planned, I’ve heard that the destination is a C-type asteroid. A C-type is also a rocky asteroid, but it contains more organic - or carbon-based - matter. So this mission might discover something related to the origin of life. I hope that this second asteroid explorer becomes a reality, and that a third one travels to a D-type asteroid. A D-type asteroid is thought to contain volatile substances such as ice.
Most of the meteorites that fall to Earth are thought to be coming from the asteroid belt. For that reason, what we know about asteroids is surmised based on what we’ve learned about meteorites with similar characteristics. For example, S-type asteroids such as Itokawa correspond with meteorites known as "ordinary chondrite." But meteorites that correspond to D-type asteroids rarely fall to Earth, so we don’t understand their composition that well yet. D-type asteroids are thought to have a make-up similar to that of comets, which are the subject of my research, so I’m very interested in them. The main component of comets is ice; they are primitive celestial bodies thought to carry information from the time the Solar System was born.
I would like to continue to study small celestial bodies, and to try to solve the mysteries of the birth of the Solar System and the origin of life. So I am hoping that HAYABUSA was only the first of many such missions.