Following in the Footsteps of a Lost Pioneer to Reach Venus
Kozo Otani, operations planning support software development and operations engineer, NEC Aerospace Systems
AKATSUKI's five on-board cameras will capture images of Venus by using a variety of modes. To control these cameras, new operations planning support software was introduced for AKATSUKI.
When development started, two people were in charge: Masafumi Kimura (described in the highlighted article below) and Kozo Otani. However, Masafumi Kimura, a veteran with years of experience, died suddenly during development. "What would Mr. Kimura have done?" Mr. Otani asked himself, relying on the support of those around him as he followed in his mentor's footsteps to finish the system.
- You helped develop the operations support software and are currently using the software as a member of the AKATSUKI operations team. What can you tell me about the software?
Otani: The software, which is called PCNAV, is used to help create probe operations plans. For AKATSUKI, the main mission is to capture images of Venus and send them to Earth.
During observation, it is necessary to aim the surface on which the cameras are installed towards Venus, and, to send the image data to Earth, it is naturally necessary to aim the antenna towards Earth. At the same time, no sunlight can be permitted to enter the camera's field of vision. This means that there are actually times that, even though we want to aim the cameras at Venus, we cannot because doing so would allow sunlight into the field of vision. AKATSUKI will be used to observe Venus under various conditions such as these.
If AKATSUKI can successfully enter Venus's orbit, it will revolve around Venus once every 30 hours. Which of the probe's five on-board cameras to use will change depending on where in the orbit AKATSUKI is. In addition, as Venus revolves around the Sun, the orientation of the Sun also changes. In other words, the direction in which the cameras must not be aimed and the probe attitudes that must not be used to avoid heat are not fixed and constantly change.
The researchers who will observe Venus have various requirements. As a manufacturer, we wanted to devise a way to create an operations plan that can change according to needs as flexibly as possible. For this, it is more useful to have software that automatically judges various conditions and then outputs the commands to send to the probe than to prepare templates of fixed commands.
Concerning the software PCNAV, the PC in the name refers to the AKATSUKI project name PLANET-C. When you enter what sorts of operations you want to perform into the software, the software automatically judges various conditions and eventually outputs the commands to send to the probe.
- Can you explain the software in a little more detail?
Otani: These are the PCNAV windows. Information related to operations is arranged in an intuitive and easy-to-understand way. The center shows the waxing and waning of Venus and its apparent size. This window also shows where in the orbit the probe is.
PCNAV operation windows
As an example, the user might enter a request to perform observations at a certain time. The software then analyzes judgment conditions such as the direction of the Sun and Earth, the direction of the shadow of Venus, the angle of the orbit around Venus, and the period of time during which communication between AKATSUKI and the Usuda Deep Space Center (UDSC) is possible.
The software then uses the conditions to judge whether the entered request can be safely carried out, and then returns a result indicating that the request can be carried out or that there is a problem. Next, the software creates an operations plan consisting of a series of steps for safely carrying out the request and then outputs commands that can be directly sent to the probe.
- So, the software can only be used after AKATSUKI enters the orbit around Venus?
Otani: No, the software was designed so that it can output operations plans even during AKATSUKI's trip to Venus because several observations were planned for. For example, during the last third of October, the probe captured images of the ecliptic plane to observe zodiacal light.
- It seems like coordinating all of this would have been difficult for just one person. Have you always been involved in this field?
Otani: No, actually. I spent my time in college researching probe orbit determination at the National Aerospace Laboratory of Japan (NAL), which is now known as the Japan Aerospace Exploration Agency (JAXA) Chofu Aerospace Center (CAC). I researched methods for calculating where and how a probe is flying in the Solar System based on data received on the ground. I started working at NEC Aerospace Systems because I wanted to do this sort of work, but I initially worked in a different division for four and a half years. Luckily, I was eventually recommended due to my research of orbit determination and was moved to my current division in 2004.
After that, I was involved in the lunar orbit explorer Kaguya and started participating in the AKATSUKI project in 2008.
- Was the development of PCNAV Mr. Kimura's idea?
Otani: Yes, we originally had the EPNAV software, which was created for the operations of the asteroid explorer Hayabusa. Mr. Kimura lead the development of EPNAV, and he felt that similar operations support software would definitely be required for AKATSUKI, which would orbit Venus.
- What sorts of differences are there between EPNAV and PCNAV?
Otani: The EPNAV software was intended for operations to support the daily navigation of Hayabusa using its ion engines. The EP in the name refers to electric propulsion. EPNAV was designed by NEC engineers who participated in supporting Hayabusa operations, and was created for their own use.
The PCNAV software is intended for creating observation plans used as the probe is navigated from Earth to Venus, as well as after the probe enters the orbit around Venus. This software is therefore a tool for effectively and efficiently observing Venus while considering various conditions. PCNAV has a major role not only in the operations of the main part of the probe, but also in creating observation plans.
This software is designed to be used by members of the AKATSUKI operations team, including researchers who are not accustomed to satellite operations. Therefore, the software has to have an easy-to-use graphical user interface (GUI). During the development of PCNAV, we invested a lot of effort in creating a GUI that was extremely easy to use. The software had to be easy for anyone to use. The GUI window design was mostly done by Mr. Kimura.
- So you're saying that developing the software was a coordinated effort?
Otani: Mr. Kimura was a really exceptional engineer. He freely used equations and calculations as though he were using nothing more complicated than scissors and glue. Not only that, but he had tons of experience. He was involved in probe operations from the time that Japan first launched Sakigake and Suisei into the Solar System, and, even though we failed to enter the orbit of Mars, he was instrumental in leading the orbit operations as the Mars explorer Nozomi struggled towards Mars. (This is described in detail in Shinya Matsuura's "Terrible journey: Mars "Nozomi" took in 12 years".) In other words, Mr. Kimura had loads of the sort of know-how that can only be acquired through life-and-death experiences on the field of battle.
Mr. Kimura applied the know-how he gained during his work to PCNAV to help reduce the possibility of mistakes. As I only had experience with the Kaguya operations, I learned a lot from him.
However, in August 2009, Mr. Kimura died of a sudden illness. The death was so sudden that no one could really believe he was gone.
At that time, we did not even have the complete specifications in document form. I'm sure that Mr. Kimura's head was just full of ideas for how to go about finishing the PCNAV software. Unfortunately, he died before all of the specifications could be documented.
I ended up having to finish developing PCNAV on my own. Every day was a struggle and a series of trials and errors. I found myself constantly wishing that Mr. Kimura was still around. In the end, I only managed to finish the software thanks to the support of Mr. Oshima, the project manager, and many other co-workers.
- How did you continue to develop the software after Mr. Kimura died?
Otani: I talked to people related to the project to gain a clear understanding of the user needs. For example, each of the five on-board cameras has a different observation target, person in charge, and operation requirements. I talked to space research professor Takeshi Imamura (an AKATSUKI project scientist), asked about camera-related needs, and eventually put together a list of several patterns for using the cameras in combination while in the orbit around Venus. I then set up the software so that a user could create an operations plan by selecting the pattern to use.
As the launch date approached, various specific user requirements for the software became apparent. I found out about these needs, determined which ones were feasible, and continued working to develop the specifications.
I continue to do this work even now. One aspect of software is that it must be corrected to match changing conditions even as it is used. I suspect that, when the actual observations of Venus begin, there will be more new requirements. If so, PCNAV will probably have to be upgraded even more. My goal is to ensure that the software is reliable and makes it possible to do what those in charge of operations want to do.
- What do you want to do next?
Otani: During my most recent work, I helped develop the software for AKATSUKI, which is bound for Venus, an inner planet, but I want to modify the software so that it can also be used for outer planets. Operations support software similar to PCNAV will probably also be required for the successor to Hayabusa. When we travel further into the Solar System, I suspect that we will need yet another new system. I'm looking forward to that.
On the fourth floor in a certain building at the NEC Fuchu Plant, there is a desk that lost its owner. A file on which "PLANET-C -PCNAV" is written remains there. Standing in front of that desk, Otani realized that he had inherited Kimura's dreams of planetary exploration.
"I think I achieved most of what Mr. Kimura planned."
Following Kimura's sudden death, Otani tried to do what he thought Kimura would have as he worked on AKATSUKI. Perhaps, even now, he can see his mentor ahead of him, pushing ever forward.
Researched and written by Shinya Matsuura, October 27, 2010
Remaining forever in our memories
Masafumi Kimura was born in Fukuyama, Hiroshima.
He joined NEC Aerospace Systems in 1983.
Immediately after starting work, he was put in charge of the orbit operations for the Halley's Comet probes Sakigake and Suisei.
In 1990, Kimura was instrumental during the orbit operations for Hiten, which was the first probe to successfully enter a moon swing-by orbit, and he then applied this experience to the launch of the Mars explorer Nozomi in 1998. Due to an electrical circuit failure, it was necessary to give up on entering the orbit of Mars, but the mission efforts were praised in "The Heroes at the End of the Nozomi Mission" (p. 429 of "A Terrible Journey"). After learning from the above missions, Kimura and his successors went on to launch Hayabusa in 2003 and Kaguya in 2007, and formed a powerful team that has delivered striking results up until now. Kimura was hospitalized with a sudden illness in June 2009 and passed away on August 11th, 2009, without ever seeing the launch of AKATSUKI, which he helped develop, or Hayabusa's return to Earth. He was 49 years old.
Kimura's co-workers successfully got Hayabusa back to Earth and guided AKATSUKI to Venus, as Kimura would have wanted. AKATSUKI bears a plate on which the memories his acquaintances have of him are inscribed.
The title of this engineer interview, "To the Morning Star!", refers to everyone's memories of Kimura.
AKATSUKI message, <group application 37> plate
Words written by members of Mr. Kimura's family and 190 acquaintances
November 17, 2010
Written by Masahiro Ogasawara,
Senior Expert of Space Systems and Public Information Systems Division,
NEC Aerospace Systems
NEC Aerospace Systems
Joined the company in 2000.
He started developing operations software with the space division in October 2004 and has mainly been in charge of SELENE (Kaguya) and OICETS (Kirari) operations.
In October 2008, he was put in charge of the operations planning software for PLANET-C (AKATSUKI).