 Mukai: The greatest advantage of the space station orbiting the Earth is the ability to adjust its on-board gravity to zero. In combination with the centrifuge, it is possible to create any level of gravity we need between 0 G and 1 G. On the ground, the base is always 1 G. We can have hyper-G, like 1.2 G, 1.5 G and 2 G, but we cannot create long-term low gravity. Earth has a unique environment, which allows humans and other living entities to exist. But the only familiar gravity level for us is 1 G, so we do not know if 0.5 G would be better for us. For example, an experiment with cell cultures in space sometimes indicates that multiplication of cells increases in an environment with gravity lower than 1 G. Without leaving Earth, we will not be able to find the best level of gravity for us. Although seeking our future in space is important, going to space will also give us a chance to look at why humans have come to be the shape we are, and why there is such a wide variety of living entities in our world.
I am often asked what I found most fascinating in space, and it was to realize how much we are controlled by gravity. I experienced that when I returned to Earth after a stay in the world of zero gravity. We never really think about it, as we are born and live all our lives with it. When I came back, I vividly felt that, as well as other things, I was being pulled down to the planet’s core by a strong force.
To learn more about the phenomena caused by gravity, we need a gravity-free environment. It’s like testing eyesight. To test how much an eye can see in darkness, you need a dark room. In pitch darkness, you can measure the volume of light an eye can catch. To study the function of an ear, a room with absolute silence is essential, so that we can test how sound is heard. Accordingly, if we want to learn more about our own planet, we must observe it at a distance, and I believe that the space station will be the place for that purpose.
Akiba: Space is still not an easy destination for us to travel to. And yet, we have reached the stage of thinking about commercializing space, and have started thinking about the need to design a system of laws covering human space travel, including space tourism.
Japan has great rockets, but I must say that this is 20th-century technology. We need to realize that the transportation means of the 21st century are going to be very different. Some people who have watched a rocket launch on site say that they were moved by the sound. But I don’t think that they could bear it if they had to hear that sound every day. My proposed solution is a system where rockets will launched from an airplane. The current system allows us only 20 to 30 rocket launches a year, at most. If, say, 10 tons of equipment and supplies are carried each time, that means we are limited to only 200 to 300 tons transported to space per year. Using aircraft, we will be able to perform several hundred launches per year. Manned space activities are, of course, important, but I think it is vital to develop the next generation of space transportation vehicle, as well as robotics, which play a key role in dangerous environments such as space.
Ono: Some in the audience might have thought the same when listening to Prof. Akiba, but it is true that the concept of rockets has not changed at all since I was with ISAS. I have the impression that, since Germany’s V2 rocket, no fundamental technological innovation for the system has been made.
Tachikawa: I agree. To a layman’s eye, as Mr. Ono said, not much conceptual progress has been made in space transportation systems for the last 50 years. Therefore, as Prof. Akiba suggests, I think that we need fresh concepts for space utilization and access. This will give the younger generation something to aspire to.
Ono: You cannot have success in a new endeavor without failure. But if an organization cannot learn from its failures, I am afraid that it is not qualified to make new attempts. We, of course, are highly critical when a rocket launch fails, because we hope the organization will overcome the failure and improve. I am not saying that development should be stopped. We are looking for risk takers, but at the end of the day we do not need those who do not learn from failure. As far as budget is concerned, a large amount cannot be given, but we would like to meet the expected number as much as possible.
Matogawa: Today, the success rate for rocket launches around the world is about 90 per cent, which means that one out of ten launches fails. Let me remind you that failure is the result of someone’s best efforts, and I think that “challenge” is still a keyword to space development. Having said that, the level of the technology that allows one failed launch out of ten is not mature enough when we are looking at moving our activities to space. You would not fly if you heard that 100 airplanes left Narita airport for the moon but 10 of them were expected to crash. In that sense, the maturity of space technology is far from that of aircraft. To enhance space technology, as Prof. Akiba pointed out earlier, we should be aware that space development is no longer something to be done only by the state. It is time for individual citizens to be aware and involved in it.
Finally, all the panelists are going to address you with their final words.
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