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Raumfahrt - Im Interview: Hitoshi Kuninaka / Project Manager, Asteroid Explorer Hayabusa2

Ein Weg zur Weltraumforschung

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In June 2010, asteroid explorer Hayabusa completed a seven-year journey of about 6 billion kilometers, returning to Earth with dust particles from an asteroid. Its successor, Hayabusa2, was launched on an H-IIA Launch Vehicle from the Tanegashima Space Center on December 3, 2014. Hayabusa2 will make its own journey to asteroid 1999 JU3, carrying our hopes into outer space. Just before launch, we asked Project Manager Hitoshi Kuninaka to talk about the mission.
The launch is nothing more than the starting line
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— The Japanese people were excited at Hayabusa2’s launch.
Yes. But I believe that the fastest way to an engineering success is calmly going about your work according to plan. So while I know they were cheering us on, I took care to do my work without being distracted. All I want to say is that when the rocket launches, we were just standing at the starting line. The mission will continue for a long time, until the explorer’s return in 2020, so I want to do the job right – to make the mission a success, to make sure that Hayabusa2 returns to Earth and delivers an asteroid sample to scientists.
— What is the post-launch schedule?
After launch, the explorer will spend a year near Earth. During this time it will use its ion engines to accelerate, come back toward Earth next winter, and then use Earth’s gravity in a swing-by to accelerate more. It will arrive at asteroid 1999 JU3 around June 2018, and then spend a year and a half flying over the body. During that time Hayabusa2 will send a lander to the asteroid, use an impactor to create an artificial crater on the asteroid’s surface, and extract subsurface materials. The explorer will also drop three small MINERVA (MIcro/Nano Experimental Robot Vehicle for Asteroid) robots on the asteroid, which will make their own observations. Hayabusa2 will leave the asteroid around November 2019, and return to Earth around November 2020. Only the capsule, which will have separated from the explorer, will actually land, while the explorer itself will alter its orbit and head back into outer space.
— The first Hayabusa was launched from Uchinoura on an M-V Launch Vehicle, while this explorer went up on an H-IIA Launch Vehicle from Tanegashima. How is this launch different?
Hayabusa2 launched on an H-IIA, and in fact my career in the space industry began at Tanegashima. My first assignment after joining the Institute of Space and Astronautical Science (ISAS) was a satellite called SFU. I was there as an assistant during launch-pad work at Tanegashima. It was my first experience being out in the field, so I felt like I was coming back to where my career started.
Learning about the Solar System’s past is not the only objective
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— What are Hayabusa2’s objectives?
There are three objectives. The first is to expand our scientific knowledge. By analyzing the asteroid’s materials, we will get closer to learning about the Solar System’s origins and evolution, as well as the emergence and history of life. Hayabusa2’s target, 1999 JU3, has carbon, so we could discover water or organic materials, which are the basic building blocks of life.
The second objective is to maintain and develop Japan’s unique technology for exploring outer space. This precision explorer’s construction is the sum of Japanese technological, scientific and industrial capability. It is important for Japan to use the experience we’ve gained from the many failures the first Hayabusa experienced, in order to make our space technology even more sophisticated.
The third objective is to venture out into the frontier and broaden the range of human activity in space. We expect this to have a ripple effect in industry and society, to raise our international profile, and to provide an educational experience for today’s youth. For example, I think it will be difficult for a country to undertake a manned mission to Mars all on its own – such a mission has to involve international collaboration. The important questions are, how much of a technological contribution Japan can make, and how visible can we make Japan’s presence. In addition, since space exploration missions are not short-term projects, we will need the help of today’s young generation. We will teach the people who will succeed us, and continue the exploration of space.
— What upgrades have been made since the first Hayabusa?
A variety of upgrades have been made to Hayabusa2, using the technology from the first explorer and the experience we gained on that mission. For example, we have boosted the ion engines’ thrust by 25% and made them sturdier. Microwave-discharge ion engines are long-lasting and reliable, and their fuel consumption rate is 10 times better than chemical propulsion. Hayabusa was the first successful attempt at a practical application of this technology, and since then we have further improved performance. In addition, the first explorer could only send and receive X-band (8 GHz) signals, but the new one can also communicate along the Ka-band (32 GHz). Thus the explorer will be able to send large volumes of data to Earth. Because of that, we have added a second antenna, but despite the addition the explorer is still only half as heavy as the first one. We have also added much more decision-making on the ground to the autonomous navigation technology we demonstrated with Hayabusa. When Hayabusa2 is more than 100 meters from the asteroid, it will be controlled by an operator on Earth. When it comes within 100 meters, Hayabusa2 will operate autonomously. The asteroid 1999 JU3 is 300 million kilometers from Earth, and it will take 40 minutes for the explorer to respond to a command and send information back to Earth, so it will have to decide where to land on its own. And the landing process will be an improvement from the last mission: rather than landing wherever it can, Hayabusa2 will decide where it wants to land.
— So it will select a landing site with high scientific value, pinpoint it, land, and extract a sample?
The purpose of Hayabusa was to demonstrate engineering technology – the ion engines and autonomous navigation – but for this mission planetary scientists around the world asked us to build a explorer that fulfills a scientific purpose. One of our responses is the impactor. We will fire a metal slug at the asteroid’s surface at a speed of 2 kilometers per second, create an artificial crater, and extract a subsurface sample. Asteroids contain the history of the Solar System’s birth, but due to the influence of the Sun and solar wind, their surface is weathered. Therefore, we want to get inside and investigate fresh materials. This is a new challenge for us.
Building on past missions is a huge advantage
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— Can you reflect back on Hayabusa2’s development?
The project had a lot of delays – it was a very difficult explorer to develop. Even though we had experience from developing the first Hayabusa 10 years ago, creating a new system was very challenging. We applied strict rules of “configuration management,” which meant that we couldn’t proceed until even the smallest design changes were thoroughly checked and reflected in the drawings. So simply revising the drawings required a lot of effort. Plus, we didn’t get the budget for Hayabusa2 and start full-on development until the spring of 2012, so we only had two-and-a-half years before the launch date. For a mission like this, you calculate things like the orbit of the target asteroid, and find a launch window that gives you the most efficient path to your destination. So we had to work really hard, because we couldn’t let our chance get away – we had to launch in winter of 2014. There have been many difficulties over the past two-and-a-half years, so we had no time for breaks, but we were able to solve problems one at a time and build an extremely complex explorer. The unified Hayabusa2 project team, including the people at the private-sector companies involved in the mission, really made a great effort. Also, the accumulated achievements and technology that ISAS has built up over the past 50 years were a big advantage. I can say with confidence that we have built a good explorer.
— The last Hayabusa was saved from a life-threatening crisis because you had secretly installed cross-networked circuitry in the ion engines. Hayabusa2 was built under a strict management system, so you don’t seem to have had the same degree of freedom.
That’s right. But JAXA took the lead in the design of some of the components – we call it “JAXA integration.” But we had a lot of freedom to incorporate ingenuity. The components are pretty interesting. They’re packed with off-the-wall ideas and technology. Some examples are the DCAM3 detachable camera, the impactor that will make the artificial crater, and MINERVA 2, the second of the MINERVA bots. I wasn’t directly involved in their development, but it looked like the teams were having a lot of fun. The impactor was created entirely with Japanese technology that is so sophisticated you’d think it’s not from this world. Stay tuned to see how these components perform in space.
— Hayabusa2 also has a component made with cash donations, right?
That’s CAM-C, the camera on the end of the sampler horn. We also plan to use the donations we received for ground-based systems. I’d like to take this opportunity to express our deep, heartfelt gratitude for everyone’s support.
— What did you have to watch out for when leading the team as the project manager?
Hayabusa2 is an amalgamation of diverse specialized technology – the mechanical parts, heat-related equipment, communications equipment, and the ion engines – and it was completed as a single system. I doubt any one person is proficient at all of these technologies. I, for one, am not some superman with a mastery of all these fields. That’s why I gave the people working on the project as free a hand as possible, and I respected their decisions. When I questioned a decision, I first tried to listen to what they had to say. I was careful to create an environment where individuals with expertise could display their inventiveness. However, of course, when things like cost and resources pushed me to make a decision, I acted like a professional manager and made the decisions I had to make, taking full responsibility for them.
Getting involved in planning is pointless unless it’s in a leading role
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— What was your personal goal for Hayabusa2?
I think I’d like to pave the way for the idea of exploration. Space development has to be done on the state level. For example, the private sector can’t turn a profit doing such things as disaster monitoring and basic science, so that’s where JAXA takes the lead. On the other hand, there are things the private sector can do, like rocket and satellite development and operation, and in these areas, private companies are taking over from JAXA. In that sense, JAXA’s range of activities has gradually become more narrow. But we can’t change that, because JAXA purpose as an organization is researching and developing new technologies. So if you ask what there is for us to do that the private sector hasn’t gotten involved in, I think the answer is exploration. In other words, rather than depending on the Earth’s limited resources, we should focus on humans doing more in space. With Hayabusa, I want to show where the path to exploration lies.
As for the asteroid, its gravity is weak, making it easy to approach and leave, but since the viable landing spots have a hard surface, I think it is also effective as a test site for a manned mission to Mars. Right now only Japan has the technology to go to an asteroid, land, and then return to Earth. What we demonstrated with Hayabusa was something no one else in the world had ever done, and that was extremely valuable. It’s proof that Japan possesses advanced technological expertise, and that’s why we are in a position to ask the world for help – because Hayabusa2 is a more sophisticated version of the original technology. I will do everything possible to make the mission a success, and lead the way for Japan to become more involved and have a greater say in international exploration projects.
— How meaningful is being able to lead the planning process of an international mission?
I don’t think there’s a point in being involved in planning unless we’re leading. It’s important for Japan to be able to act independently while also collaborating with other space agencies, and I think this is why we embarked on the Hayabusa2 mission. I think the reason we were able to build Hayabusa2 in just two-and-a-half years is that Japan took the lead on construction, and the manager for each onboard device had an overall understanding of what Hayabusa2 was supposed to be. In other words, they had an accurate idea of what role their devices were going to play, and how to coordinate them with other components. I was in charge of the ion engines on the first Hayabusa, but I was completely engrossed in my own job and couldn’t see the big picture. I understood the engines, but I didn’t think about what they could do when connected with another component. I think only the project manager, Junichiro Kawaguchi, had that overall idea. But with Hayabusa2 we’ve learned from that first experience, and we’ve been able to share a vision with everyone of what Japanese technology can do when everyone works together. I believe the reason we’ve been able to get to the finish line while operating under various constraints – costs, schedules, performance and manpower – is that all the managers understood the entire project and were highly motivated.
— How has Hayabusa’s success contributed to increasing the international community’s trust in Japan.
In addition to the United States and Australia, who helped with the previous mission, for Hayabusa2 we’ve also formed a partnership with Europe. Specifically, NASA will let us use its global outer space network to conduct the explorer’s operations; Australia will let us use its vast desert to land the explorer (for a fee); and the German Aerospace Center, known as DLR, is handling MASCOT (Mobile Asteroid Surface Scout), the small lander on Hayabusa2. MASCOT will detach from Hayabusa2, land on the asteroid, and make observations from up close. MASCOT carries a near-infrared imaging microscope developed by France’s aerospace agency, CNES, which will investigate things like the types of minerals on the asteroid’s surface, so I think we’ll be able to get some interesting data. By the way, did you know that the other day the Rosetta comet explorer’s lander, Philae, landed on the comet Churyumov-Gerasimenko between Mars and Jupiter? It was the DLR that built Philae, the first machine to ever land on a comet. It’s a big responsibility when you team up with people who perform such amazing missions, but I feel it’s so very worthwhile.
Epic journeys into space create the joy of new discoveries
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— What are your thoughts on missions that will come after Hayabusa2?
Personally, I want to do a mission to Jupiter, and if I had the chance to build a new explorer, I would want to try to make it entirely out of Japanese-made parts. When you have a set schedule and are building within a budget, sometimes it’s better to procure a part from overseas rather than make it ourselves. Hayabusa2 also has foreign-made components in it, but if something goes wrong with them then you run into information disclosure issues and it’s hard to make any progress. They used to say it was a sounder approach to purchase American-made ion engines, but I think there’s significance in doing it yourself, even if it’s a trying experience. I believe Hayabusa made it back because of our masterful control of the ion engines, but we were only able to do that because we had made all the parts ourselves. If a component we procure from abroad has a black box, then we can’t manipulate it as well. That’s why I want to make as many components as possible in Japan.
I think Japan’s fiscal situation will make it tough to put together a plan for the next mission, but even so I want to somehow pave the way for an epic journey into space. I think Hayabusa’s technology is also applicable to exploring Mars, and I believe that Japan’s space technology still has much more potential. I want us to build the technological foundation, train capable personnel who are up to the challenge, and prepare, so that we can start development soon after we get the budget for our next mission.
— An epic journey into space is no easy feat. Where do you get the passion that makes you want to embark on this expedition?
I think it’s because building a vehicle that flies great distances, whether an airplane or a space explorer like Hayabusa, involves a desire to go wherever you want with complete freedom. First we conquered the Earth with airplanes. Then we built rockets to go into near space. And now that technology is well established, so next we are aiming for more distant space. Exploration is in the human heart, so this is the path we must walk. Thus we will be able to see entirely new things, which is a supreme joy. This is why we undertake epic journeys into space. When Hayabusa approached the asteroid Itokawa and showed it to us for the first time, that was fun. I still clearly remember the joy of that moment. They say that 1999 JU3, the asteroid Hayabusa2 is targeting, is just a round black body, but so far we have only been able to see it as a speck through a telescope, so I want to know just what sort of shape it has. The asteroid might even have satellites orbiting around it. It’ll be a lot of fun when Hayabusa2 shows us what it looks like.
— Finally, could you give a message to everyone?
Hayabusa2 is a vessel we Japanese designed ourselves, and we are sending out into space with our own hands. Nobody knows what kinds of adventures await, but it is sure to be an interesting voyage. Please follow Hayabusa’s journey, and see what happens. We’re all so excited!
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Hitoshi Kuninaka, Ph.D.
Hironobu Yokota
Project Manager, Asteroid Explorer Hayabusa2 
Professor of Space Flight, Department of Space Flight Systems, Institute of Space and Astronautical Science, JAXA
Dr. Kuninaka completed a Ph.D. program in aerodynamics at the University of Tokyo’s School of Engineering in 1988. That same year he took up a new post at the Institute of Space and Astronautical Science, which is now part of JAXA. In 2005, Dr. Kuninaka became a professor of aerospace engineering at the University of Tokyo’s School of Engineering. In 2011 he served as Lunar and Planetary Exploration Program Group Director, then assumed his current post in 2012. Dr. Kuninaka’s areas of expertise are electric propulsion and plasma engineering. He has been involved in the development of the ion engines for the Hayabusa asteroid explorers.
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Quelle: JAXA

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