One other thing is IoT*1, where commu-nication shifts from places with people to data sensing in places without people, for example, on the ocean. Ocean surface tem-perature, wind direction / velocity, and atmo-spheric pressure, etc., have a great inuence on the weather, and as such are important data, but there is no easy-to-use network on the ocean right now. However, if the ocean is networked by developing more exible satel-lite communications technology, then it will be possible to collect data in real time. You can say that it is something like Beyond 5G, which comes after 5G.Q: Large-capacity optical communication technologies are becoming important, ar-en’t they?KADOWAKI Optical link can provide a larger communications capacity than radio waves. Additionally, onboard satellite com-ponents for optical communications can be made smaller than the ones required for radio communication, so it will be easy to mount them on the increasing numbers of small sat-ellites and microsatellites in the future.Another major feature of optical commu-nication is its capability to realize quantum cryptographic communications. In quantum cryptographic communications using optical wave, quantum keys must be distributed over an optical network, and at present, terrestrial optical ber transmission cannot reach very far. However, if satellites and the ground are connected via optical communication, then quantum keys can be delivered across con-tinents. There are already countries overseas that have succeeded in sending quantum keys via satellite by using relatively large satel-lites, but we are conducting research on send-ing quantum keys via small satellites.As for quantum cryptography, NICT has already conducted basic experiments on the feasibility of quantum cryptographic com-munications by developing SOTA*2, a small optical communications device for satel-lites, and mounting it onto a 50 kg class SOCRATES*3 (developed by Advanced En-gineering Services Co., Ltd. and launched by JAXA in 2014) microsatellite.Additionally, if the satellites are connect-ed to the Internet, then they may be hacked like on terrestrial networks. NICT also has a department that studies quantum cryptogra-phy and cybersecurity, so I expect that they will collaborate as a team and promote mea-sures against hacking.■Implementing a next-generation engineering test satelliteNext, full-scale experiments with ETS-9*4 are getting closer and closer, aren’t they?KADOWAKI We have started the “ETS-9 Satellite Communications Project” demon-stration project to respond to new communi-cations demands in recent years. This is an attempt to demonstrate 10 Gbps class optical satellite communications between a geosta-tionary satellite and the ground, and to devel-op and demonstrate satellite communication technologies in the so-called Ka-band (20 / 30 GHz) that are more exible than those us-ing radio waves. It will be the rst time in the world to demonstrate 10 Gbps optical com-munication between a geostationary satellite and the ground.The radio wave transmission antenna is adopting active phased array antenna tech-nology. With this, we can electronically scan beams via a digitized beam former, and it is an important fundamental technology for re-alizing large-capacity communication with 100-beam class multi-beams in the future. Additionally, the bandwidth allocated to each beam can be exibly changed by using digi-tal channelizer technology. These technolo-gies also enable us to dynamically control the beam’s direction and bandwidth, increasing radio wave utilization efciency.NICT is currently developing an onboard wireless communication device in collabo-ration with universities and manufacturers, and, if all goes well, ETS-9 will be launched in 2022.■Wanting participation of youth who will lead the next generationQ: What is the future outlook for SPIF’s activities?KADOWAKI Technological progress in this eld is extremely fast. If something like a large satellite takes ve or six years to de-velop, then it may be equipped with old technology by the time it is launched, and the longer the development time, the high-er the cost. Therefore, we have to consider shortening satellite development cycles and reducing costs by using small satellites for in-orbit demonstrations. Furthermore, we are also considering using commercial-off-the-shelf (COTS) components to reduce costs. We consider presenting a new concept of the space development process like this to be one of SPIF’s goals.To that end, we would like to receive a variety of ideas and opinions, including from universities and private companies, and lay out the direction of research and develop-ment for Japanese space communication technologies while discussing with them.We would also like to invite students to participate in SPIF and to make it into a place to talk about space together. I hope that the number of young researchers interested in satellite communications will increase.＊1 IoT: Internet of Things＊2 SOTA: Small Optical TrAnsponder ＊3 SOCRATES: Space Optical Communications Research Ad-vanced Technology Satellite＊4 ETS-9: Engineering Test Satellite-93NICT NEWS 2021 No.1
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