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HAYABUSA returns after overcoming many obstacles
Shinji Hagino, Project Manager, NEC CorporationInterview: May 20, 2010
For the development of the asteroid probe HAYABUSA, NEC joined the project as a system integrator, and Shinji Hagino, from NEC, worked as a Project Manager to lead a team of NEC engineers. Under the powerful leadership of Junichiro Kawaguchi of the ISAS of JAXA, he listened to requests of universities and research centers, collaborated with other manufacturers, and found solutions for integrating various conflicting requirements. Finally, HAYABUSA was developed, the only asteroid probe of its kind. The whole process took 14 years since 1997, when development began. Hagino saw off HAYABUSA at its launch and participated in mission operations.
Hagino, who knows everything about HAYABUSA, participated in the final operations as a member of the operations team in order to safely land the re-entry capsule in the Woomera Desert in Australia.
Designing HAYABUSA from scratch
- Please describe your work.
Hagino: I have been in charge of satellite system design since I joined NEC.
- What kind of work does system design involve?
Hagino: It involves coordinating and integrating many different elements to make them work together in one satellite. After working as a system manager, I worked for the first time as a project manager for HAYABUSA.
- What was it like developing HAYABUSA?
Hagino: It wasn't easy, I can tell you that! Normally, when developing a new satellite, we inherit the designs used in earlier models for the basic parts such as the power system and attitude control, which are referred to as the bus systems in technical parlance. Since designs that have been used until now in space should be stable, the reliability of satellite systems can be ensured by adding new sensing devices on top of them.
However, in the case of HAYABUSA, everything was new. We had to design everything from scratch. Besides the sensing devices, we had to design just about everything anew, including the power system, attitude control system, and communications system to fully satisfy the requirements. On top of that, various other unique devices such as the sampler horn and the re-entry capsule were also to be squeezed in, with the requirement that the total weight be 510 kg or less so as to allow launching with the M-V rocket (links to JAXA website). Every day was a series of discussions.
loaded on HAYABUSA
- What did you feel at the time of the launch?
Hagino: At that time, I attended the first visible pass at the Uchinoura Space Center. The first visible pass means the operations done by receiving the first radio waves from the probe following its launch. When we received the radio waves from the probe, I recalled all our struggles and was full of emotion. But, having become a project manager on the HAYABUSA project, I thought to myself that it is still too early to be filled with emotion for all the upcoming projects. Some members of our team were moved to tears, but I thought it better not to cry myself.
- Did your feelings change after becoming a project manager?
Hagino: Previously, I was working on many different things and so was apprehensive about mistakes. But, after becoming a project manager, I worked by trusting my team, so my thought was that “once it goes up, it should work.” Trusting my team in this way made me feel more reassured than when I did the work myself.
HAYABUSA has both birth parents and foster parents
- What was it like during the touchdown operations in November 2005?
Hagino: The operations for the touchdowns in November extended all the way from rehearsal until the two actual touchdowns.
Professor Kawaguchi's resoluteness was truly astounding. He stated that we'd succeed in just days, and asked us whether we were up to it and really pushing the envelope. As a result, the operations side worked frantically to meet demands and did exactly what was expected. At that time, I thought that the operations team was really something!
- What was it like during the loss of communication in December?
Hagino: I was at my wit's end. I can barely recall anything I did or thought. I only remember that, after we lost communication, I thought, “What do we do now?” Since the only apparent problem was that the probe's attitude had gone off, it seemed logical to assume that we'd be able to get it back if we could get light to strike the solar cell paddles.
For HAYABUSA, we devised a special way to attach the paddles, in a design that ensured so that no matter how off the probe's attitude got, ultimately the probe would return to a rotation perpendicular with its solar cell paddles. Therefore, at some stage, the probe's attitude would correct itself to achieve a stable pin along its main axis, causing sunlight to strike its paddles and restoring communications.
the solar cell panels
- If its attitude becomes off, won't the HAYABUSA break down due to the drop in temperature?
Hagino: Of course, this is a possibility, but it might not actually occur. HAYABUSA's design is such that its temperature can easily drop. At touchdown, it approaches the asteroid from the direction of the Sun, so that it receives the sunlight reflected off the surface of the asteroid, causing its temperature to rise rapidly. Therefore, HAYABUSA was designed to normally allow its temperature to drop within a supportable range, and, if its temperature drops excessively, it maintains its temperature through heaters.
And thus, with the exception of the side bearing the antenna, heat radiation spots are provided, allowing heat to continuously escape. If the probe's attitude becomes off and the sunlight no longer reaches the side with the antenna, the sunlight reaches the heat-radiation side and heats the probe. HAYABUSA reaches its lowest temperature when it travels toward the Sun with the correct attitude, and, while the Sun is not directly overhead, it is least likely to experience a drop in temperature.
When we lost communication with HAYABUSA, there was a 70% chance of restoring communication by the spring of 2007 per JAXA's calculations. I myself thought that communications would be restored as sunlight had to strike the solar cells at some point.
- What have HAYABUSA's development and operation been like for you?
Hagino: We ran into various difficulties during development, but in a way, it was also easy. The reason is that HAYABUSA's theme was clearly defined. We clearly knew what had to be done, and the various manufacturers that participated in the project worked in concert toward this goal under JAXA's direction, which allowed us to clear some high hurdles.
HAYABUSA's operations were also extremely challenging, but the operations team made quick progress. Every time a problem would come up, people learned and gained experience. My job was to support them. Because many times we had situations requiring a particular person, as the skills we needed were not shared, some parts of the planning were a true headache (laughs).
- What is HAYABUSA for you?
Hagino: You may consider this trite, but HAYABUSA is like a child to me. From its development to its launch, the development team worked hard to bring it up, and after it was launched, the operations team continued working hard. Unanticipated uses have been thought up and various difficulties have been conquered. I say that we've brought up HAYABUSA.
HAYABUSA thus has both birth parents and foster parents. The HAYABUSA that came back was a HAYABUSA that had been splendidly brought up.
Since 1997, when development began, Hagino has built up HAYABUSA as NEC's project manager along with professor Junichiro Kawaguchi of the ISAS of JAXA. As HAYABUSA returned to Earth during the final days of the mission, Hagino guided the re-entry capsule toward the Woomera Desert in Australia by coordinating the operations team. “Even when I myself was participating in operations, I still found myself thinking that I must avoid mistakes. What I wanted was to ensure mistake-free operations all the way to capsule re-entry and recovery.”
Researched and written by Shinya Matsuura (released July 30 , 2010)
Shinji Hagino,
Manager of Space and Satellite Systems Department,
Space Systems Division,
NEC Corporation
Joined the company in 1985. Worked 21 years on system design of scientific satellites and is currently in charge of project management of HAYABUSA and other scientific satellites.
