Team members on the frontlines of the LUCAS project who helped to bring optical communications to the unknown frontiers in space
A groundbreaking attempt to connect satellites in space through the use of an optical communication system, which offers greater speed and capacity than conventional radio waves, is about to be realized. For this JAXA-led project known as the Laser Utilizing Communication System: LUCAS, NEC designed, developed, and manufactured the optical communication system that is at the core of the system. We asked the frontline members of the team to talk about the challenges they faced and the hard work and passion they put into completing the LUCAS project.
From the design to the manufacture of the optical communication system
--What role did each of you play in the development of the LUCAS project?
Sugiho: Development of the LUCAS project began in 2015, and a data relay satellite carrying the LUCAS system was launched in November 2020. NEC was also responsible for developing and manufacturing the optical communication equipment for two other Earth observation satellites, for a total of three satellites. As the system manager, I was responsible for the overall management of the construction of the optical communication system. In this position, I supervised the series of work which involved designing the system, assembling and testing the equipment, and troubleshooting.
Yokota: During the first three years of the project, I was in charge of the structural design and assembly of parts for the equipment that serves as the emitter and receiver of the optical laser. For the next three years, I was in charge of coordinating with the project’s customer, the Japan Aerospace Exploration Agency (JAXA), and the manufacturer of the satellite itself. Whenever there was a delay in the progress of the project, I coordinated with the respective contacts early on to ensure that the overall schedule was not significantly affected.
Takei: I joined the project in 2017 when the project moved from the design and development phase to the manufacturing phase. I was in charge of the overall assembly of the equipment, but I was primarily responsible for fiber optic fusion splicing. This is the process of joining together the optical fibers of each of the devices that make up the optical communication system that was to be mounted on the satellite.
Kurogi: As a member of the System Integration & Inspection Group, I was in charge of inspecting the manufactured system. My job was to first inspect the engineering model, which is the equipment used for testing, and then feed the results back into the inspection of the flight model equipment that would actually be launched into space.
-- Please explain the innovative nature of the LUCAS project from the perspective of your work in designing and manufacturing the system from the frontlines.
Sugiho: LUCAS has achieved a high-speed signal transmission of 1.8 Gbps, which is more than seven times faster than conventional radio wave communications. The first inter-satellite optical communication experiment in 2005 was conducted using a communication method and acquisition & tracking method developed with Europe, but this time we developed methods from scratch that employed a laser beam with a wavelength of 1.5 μm. 1.5 μm is the wavelength used in terrestrial optical communications and is expected to become the standard wavelength for connecting satellites in space in the future. If successful, LUCAS will lay the foundation for optical communications in space.
Yokota: Compared to radio waves, optical communication not only allows larger volumes of data to be transmitted at higher speeds, but it also has the advantage of allowing the use of a smaller antenna compared to that for RF signals. Smaller antennas mean that satellites can be made lighter, resulting in lower launch costs. I think this is another major advantage that LUCAS will bring to the future use of this system in space.
Kurogi: LUCAS uses optical lasers to enable communications over a distance of 40,000 km between satellites orbiting the Earth. I find it absolutely amazing that this technology can connect and maintain communications between satellites over such a long distance using a laser beam that is invisible to the eye.
Takei: This project was NEC's first foray into optical communications in space between an optical data relay satellite and an Earth observation satellite. It has opened up the possibility of significant growth in optical communication technology, and I think this is another milestone for LUCAS.
The professionalism of each individual on the frontlines ensured the success of the project
-- What were the most challenging aspects of this six-year project?
Sugiho: Because it was a new communication and acquisition & tracking system, many devices and other equipment were newly developed, and as a result, many problems arose. Problems that were hidden at the design stage were revealed through testing, and these problems were solved one by one. This process was repeated over and over again. Looking back, I think this was the most strenuous part of the work for me.
Yokota: As I mentioned earlier, I was in charge of coordinating with other companies in the latter half of the project. Since I had little experience in this kind of work, I could not quite get the hang of it at first. I struggled to find my footing in the coordination meetings, and many times I was unable to firmly assert my opinions. The LUCAS system consists of three satellites: a data relay satellite and two Earth observation satellites. Since each satellite had a different person in charge, I had to change my communication method according to the character of each, and I found the coordination and communication aspect very challenging. I had to thoroughly prepare for each meeting, ensure to always be polite and respectful when speaking with each person in charge, deliver our promises on time, and get each person in charge to accept our requests. By keeping these things in mind, I was able to improve my coordination skills.
Kurogi: We had no past experience in testing space-bound optical communication equipment with our own testing equipment. Although there were engineers on our team who had worked on ground-based optical communication systems, we could not use all of their experience because free-space optics is different. The most challenging part of my work was that we had to devise our own tests one by one.
Takei: It was the same for me. Everything was new to us and there was no one to ask when we encountered things we did not understand. We had to find the best way ourselves by trial and error.
-- It seems the odds against succeeding in this project were high.
Sugiho: It is often said that connecting satellites 40,000 km apart with laser beams is as difficult as accurately shining a light from Tokyo onto a soccer ball at the top of Mt. Fuji. I believe that our success in developing such technology and manufacturing the equipment was the result of professionals giving 100% of their skills to each of the processes for which they were responsible. It was truly a project that was made successful by the hard work of each and every person on the frontlines.
The “hand of god” and “speed star”
-- I heard that Ms. Takei, who was in charge of fiber optic fusion splicing, had what you called the “hand of god.”
Sugiho: Fusion splicing involves the difficult process of joining optical fibers that are as thin as a strand of hair. Basically, it is done with a machine, but not everyone can do it. There are often cases where the fusion splicing is not precise enough, resulting in loss of light transmission. Ms. Takei’s skills in this area were outstanding.
Yokota: There are several stages in the fusion splicing process, but Ms. Takei was always asked to do the last and most important part.
Takei: The trick to fusion splicing was to make the angle of the cut surface of the fiber as perpendicular as possible. If the fusion splicing was off, we would lose one to two days, which would affect our overall schedule. I worked desperately hard to get the fusion splicing right.
-- Meanwhile, Ms. Kurogi, who was in charge of testing was called “speed star.”
Sugiho: Ms. Kurogi was in charge of inspecting each piece of equipment one by one for power and shaft misalignment. I would make the test plan, the technical staff would come up with the specific procedures, and the on-site test staff would actually inspect the equipment according to the plan. The accuracy and speed of these inspections also varied depending on the person in charge, but Ms. Kurogi was able to complete the inspections two times faster than the average person.
Kurogi: The main task of the inspector was to check whether the optical communication equipment manufactured by NEC could withstand the various environments from rocket launch to operation in space. Our job was to test the equipment’s resistance to vibration, noise, heat, and other factors during launch. Testing the equipment on the first satellite was my first experience, so I had to play things by ear, but this experience was invaluable when working on the second and third satellites. One thing I kept in mind was to focus on efficiency. I think the speedy inspections were possible as a result of our well-thought-out plans that included eliminating redundancy and consolidating work that could be done in a single task. Every day I would set a guideline for the day's work and announce it at the morning meeting so that there would be no delays in the work.
Inter-satellite optical communications as infrastructure for people's lives and economic activities
-- In what instances did you feel a sense of accomplishment while working on the project?
Takei: When we ran into a process that was not going well and we overcame the obstacle together through trial and error, it was like, "Yes! We did it!” Besides fiber optic fusion splicing, we encountered many other challenges, but we were able to overcome each one by working as a team.
Yokota: As I mentioned earlier, the first satellite with optical communications equipment was successfully launched in 2020. When this satellite was transported to Tanegashima, where the launch site is located, and launched, I felt that we had accomplished a great goal. When the second and third satellites are in orbit and optical communications are realized, I am sure I will feel an even greater sense of accomplishment.
Kurogi: I think the most memorable moment for me was also when I saw the launch of the rocket. I was not at Tanegashima to see the launch in person, but I was able to watch it on the screen in real time. It was the first satellite I had worked on after joining NEC, and it was such a huge undertaking that I almost cried watching the rocket launch. I felt that all our hard work had paid off.
-- What did you feel was unique to NEC throughout the project?
Kurogi: The thing that stood out for me was the personalities of the project members. The people in higher positions were very polite and conscientious and communicated well with us, so I never felt like I was being forced to do the work. I think in some companies there is a complete division of labor between the technical development staff and the frontline staff, but in our case, we were able to work together as a team to move the project forward.
Takei: It was the same for me. I was inspired to work hard when I saw all the people in higher positions and my colleagues working hard.
Yokota: I felt that the culture at NEC was focused on persistently responding to high-level requests from customers and partners. I also thought that the mindset of not causing trouble for people in the next process was also unique to NEC. In a previous project, I was once advised by a senior colleague to ensure that design work was always completed on schedule so as not to cause problems for frontline staff. I tried to follow this lesson in this project as well.
Sugiho: As Mr. Yokota says, it all comes down to persistence. Everyone shared the desire to make the project a success by solving problem after problem without giving up. I myself felt a sense of accomplishment in overcoming and solving difficult problems by joining forces with everyone. I think it was a really rewarding project.
-- Now that LUCAS is entering the phase of actual operation, what are your expectations for the future of LUCAS?
Sugiho: Inter-satellite optical communication systems are the infrastructure for space utilization. To be an infrastructure, it must be useful for people's daily lives and economic activities. I myself will be involved in the future operation of LUCAS, and I would like to continue my efforts to make LUCAS a truly useful infrastructure.
Takei: I hope that the equipment I was involved in building will not malfunction in space and will work beyond its expected lifetime.
Kurogi: In the future, as the use of optical communications in space becomes more widespread, it would be wonderful if future generations knew that LUCAS was a pioneer in this field.
Yokota: The inter-satellite optical communication project will not end with LUCAS. I hope that this project will lead to the next one with as little delay as possible. I also hope that this system will enter the commercialization phase as soon as possible.
-- Finally, please share your thoughts on completing this project.
Takei: I really enjoy working in space development. I would like to continue to be involved in space projects for a long time to come.
Kurogi: Using technology in space presents many technical challenges, so it is exciting to see the product of our imaginations come to life one by one. I hope more people will become interested in space.
Yokota: NEC's space business covers a wide range of areas from manufacturing to system manufacturing and operation. I believe that my job puts me in the wonderful position of having the potential to be involved in all of these areas. It is said that satellite constellations connecting many satellites will be developed in the future. I would like to promote co-creation not only within NEC but also with various partners so that we can build a network for collaboration in space projects.
Sugiho: In space development, the most important thing is human resources. My involvement in the LUCAS project has strengthened my desire to encourage young people to get involved in the space business and to further develop Japan's space development capabilities. To this end, I feel that we need to send out more and more messages about space.