User interview – Professor Keiichi Hori, JAXA

1. Please briefly outline your research.

The main research subject is fuel for rockets. I specialize in chemistry and combustion. I am doing research on the combustion of new high-energy materials for solid fuel (solid propellant).

2. Please tell us one of the research subjects you are currently working on.

Conventional polymer rubber used for solid fuel is a thermosetting rubber. When a chemical substance is added as a curing agent to the polymer and the temperature is raised, it solidifies within a certain time (becomes rubbery). Once it solidifies, however, it cannot be returned to the original state. Therefore, the control of the manufacturing process is very severe and allows no errors. This is considered to constitute a major factor in making the price of the solid fuel high.

I am doing basic research on thermoplastic resin, which is a candidate for realizing low-cost solid fuel. The thermoplastic resin can be repeatedly molded, because it hardens at room temperature and melts when heated to high temperature (It can be repeatedly melted and molded and the remaining resin can be used at a later time). This is the advantage of thermoplastic resin over thermosetting resin.

Cost reduction becomes possible because thermoplastic resin can be continuously produced in small quantities and can be stored for a long time. We can produce and save it little by little, and then finally melt it and put it into a big rocket motor. This will eliminate the need for large-scale manufacturing facilities in the future. Currently, large manufacturing facilities are required. They are used in a pulse-like (intermittent) way, i.e., they are used for a short period during the production of a large rocket but are left unused until the next rocket is produced. This is because rockets are launched only several times a year because of their limited demand.

As mentioned earlier, it is necessary to raise the temperature to melt thermoplastic resin. The control of the temperature is one of the key points in the process control. It is easy to control the temperature of the THINKY MIXER by adjusting the rotation speed. Another important factor in mixing fuels is that no bubbles be contained in the material. Conventional mixers require long-time decompression of materials using a vacuum pump before actual mixing. However, the THINKY MIXER is able to remove bubbles quickly by making use of the interaction of the two forces of rotation and revolution with vacuum decompression. Therefore, we can save time, leading to cost reduction.

* The product used in Professor Hori’s project was specially designed with enhanced safety to accommodate rocket fuel material.

3. What motivated you to go into the research field of rockets and combustion?

Well, I guess I liked rockets. During my fifth grade of elementary school, the manned Apollo spacecraft landed on the moon for the first time. That news was very fascinating. I thought that I would like to go into the world of rockets. Because I liked science, I decided to major in chemistry. It is through the field of fuel that a chemist can contribute to rockets.

4. Many people see dreams and romance in rockets. What do you feel while you are actually working in the rocket world?

It is often said that rockets have dreams. To be honest, I was surprised at the considerable public attention on “Hayabusa” (laugh). Furthermore, I did not expect that the first “Epsilon” would attract similar attention. In fact, I did not think that “Epsilon” would become popular in spite of the popularity of “Hayabusa”, and was quite surprised that the interest turned out to be very high. I feel also that there are many women who like the universe and astronomy. They often ask questions such as “I want to make my son a researcher of outer space. What should I do?”

5. You actively accept students and researchers from abroad and often give lectures at overseas universities.

I have been teaching at a university in Kazakhstan since last year. The doctoral course over there requires that each student should have a thesis advisor from a foreign country in addition to a local professor. Last year, an expert in Europe retired and I was chosen to fill his position. Furthermore, this year, I was appointed professor at Tomsk State University in Russia.

6. What is the appealing point of research for you?

It might be a strange way of saying this, but when I discover a “peculiar property”, I feel fascination. It is boring if I find just common phenomena that conform to the existing theory. It is not interesting at all when phenomena can be explained merely by some known formulas. When a strange phenomenon not easily understood is observed, it is highly delightful for me to consider what causes such a response (reaction), etc. When I reach a right solution, I feel much satisfaction and that the research has been very successful and fruitful.

7. What is the appealing point of fuel for you?

https://www.thinkymixer.com/en-gl/?p=1462&preview=true
Basically, no rocket can fly without burning fuel. The point is that fuel is “indispensable”.

8. Are you excited when a rocket is launched?

Yes, I am excited, but I get nervous more than anything.

9. What is your dream?

In the immediate future, apart from the fuel mentioned above, my dream is to make the current project successful. Devices called thrusters, which are used in the trajectory control of satellites, etc., are about to be installed in satellites. I hope that they will be used more and more. After all, I am a fuel researcher and therefore I will be happy if a rocket using my fuel is actually launched.

Remarks after the interview

Professor Keiichi Hori is carrying out the solid fuel project using thermoplastic resin together with Professor Ryojiro Akiba, former Director of the Institute of Space and Astronautical Science and a former student of Professor Hideo Itokawa, and with Professor Yasuhiro Morita, Epsilon Project Manager. I am looking forward to success in his research.
*Detailed information on THINKY MIXER ARV-310

Brief Biography of Professor Keiichi Hori

March 1982: Graduated from Department of Reaction Chemistry, Faculty of Engineering, University of Tokyo
March 1984: Received Master’s Degree, Department of Reaction Chemistry, School of Engineering, University of Tokyo
March 1987: Received Doctorate Degree, Department of Reaction Chemistry, University of Tokyo (Doctor of Engineering)
April 1988: Research Fellow (PD), Japan Society for the Promotion of Science
June 1991: Research Associate, Institute of Space and Astronautical Science
April 1999: Associate Professor, Institute of Space and Astronautical Science
April 2009: Professor, Institute of Space and Astronautical Science (to the present)

Hori and Habu Laboratory, Institute of Space and Astronautical Science (ISAS / JAXA)
http://www.isas.jaxa.jp/home/propellant/index.html