[SPREC Insight VOL.10] Promising future spin-off and spin-in space technologies: space optical communication
  • By. 김지선
  • Date. 2023-07-13
  • View. 376

■ What is space optical communication?

● Optical communication is to store information in light. The basic principle is the same as radio communication, but instead of radio waves in the tens of GHz band, light in the hundreds of THz band from visible light to near-infrared light is used.

- Since optical communication uses a higher frequency than radio waves, transmission speed is theoretically possible to send and receive data 105 times (transmission speed of radio waves is hundreds of Mbps, and optical communication is capable of tens of Gbps)

- For communication using radio waves, to reduce damage caused by interference, the International Telecommunication Union (ITU)

manages the frequency used, and therefore requires frequency permission for use, while optical communication can be used freely

● Optical communication can be divided into wired method using optical fiber on the ground and free-space optical communication using laser, which is being experimented with for 6G implementation, also called laser communication.

- Free space optical communication can be divided into ground-to-ground, space-to-space, and space-to-ground communication between satellites or deep space probes and ground stations in the earth's atmosphere.

- In this report, space-ground free space optical communication is defined and described as space optical communication.

● This report deals with space optical communication (space-to-ground), which is the most difficult and ultimately challenging technology among free space optical communications.

■ Since visible light and infrared rays are used to transmit and receive information, the difficulty of astronomical observation using an optical telescope is applied as it is, and therefore, technologies for this are being developed.

● Cosmic optical communication using lasers can have various benefits due to high directivity, but it requires precise recognition, orientation, and tracking (Acquisition, Pointing, Tracking) technology accordingly.

● In general, signals in wireless communication suffer from loss due to absorption and scattering by the atmosphere, and optical communication suffers from greater absorption and scattering than radio waves due to its short wavelength, requiring countermeasures.

● As infrared and visible light regions are used, all light used in daily life, such as sunlight, acts as noise, so a technology that can distinguish between light used in optical communication and background light is required.

■ Efforts for commercialization using technology verification satellites are accelerating, centered on advanced countries in space

● Technology verification cases for application to small satellites that can be deployed quickly and at low cost, which are essential for commercial use

- NASA's Optical Communication and Sensor Demonstration demonstrates the precision-oriented performance of cube satellites and the communication potential of small optical communication modules

- NASA's TeraByte InfraRed Delivery demonstrates the possibility of ultra-high-speed optical communication of 200 Gbps utilizing the advantages of low earth orbit

- NASA's CubeSat Laser Infrared Crosslink and German Aerospace Agency DLR's Optical Space InfraRed Downlink System demonstrate the possibility of using optical communication between cube satellites and low-cost mobile ground stations

● Technology verification case for building space optical communication relay network for stable communication

- NASA's Laser Communications Relay Demonstration uses geostationary satellites for stable communication with ground stations, and uses two ground stations in California and Hawaii to respond to local weather phenomena.

- NASA's Integrated LCRD LEO User Modem and Amplifier Terminal demonstrates optical communication relay between low earth orbit - geostationary earth orbit - ground station

- ESA's European Data Relay System demonstrates optical communication technology between geostationary satellites and uses radio waves for communication with ground stations

● Case of technology verification to overcome the atmospheric effect

- NASA's Optical PAyload for Lasercomm Science proves its effectiveness by using adaptive optics for ground stations for optical communication with the ISS

- In addition, failure factors that may occur when communicating with fast-moving low-orbit satellites are identified, and the performance of ground station beacon lasers required to accurately orient ground stations in space is verified.

● Focus on demonstration of long-distance space optical communication technology that can be efficiently used for space exploration missions

- NASA's Lunar Laser Communication Demonstration demonstrates long-distance space optical communication applicable to lunar exploration (400,000 km)

- NASA plans to demonstrate 300 million km space optical communication by applying Deep Space Optical Communications technology, which can be applied to deep space exploration, to the Psyche asteroid exploration mission

- NASA's Orion Artemis-2 Optical Communication System will utilize existing optical communication technology to demonstrate real-time communication for manned lunar exploration missions

■ Current state of technology in Korea

● Domestic space technology is being developed centering on free space optical communication linked to 6G, and is still in its infancy. Equipped with all elements such as ground station and manpower training

■ Future Prospects and Implications

● The need for space optical communication will further increase as space advanced countries transition into the era of new space in earnest.

- In order to form a private sector-led space industry ecosystem, it is important to flourish services using private micro/cube satellites, and space optical communication, which allows free use of frequencies and enables low-cost, small-sized, lightweight, high-speed, and large-capacity communication, is an essential technology for this.

- The growth of the private satellite market will be accelerated by alleviating the radio frequency depletion problem and providing opportunities for more private companies to enter the microsatellite business.

● Convergence technologies such as terrestrial sensors (CCTV), the Internet of Things, and the Korean Satellite Navigation System (KPS) will emerge, resulting in enormous economic effects by creating new values and reducing social economic losses.

● Countries with well-equipped terrestrial high-speed Internet infrastructure such as Korea are expected to lead the market.

- Since space optical communication cannot simultaneously communicate with multiple users on the ground unlike radio waves, ground station information must be shared through ground infrastructure, so the market expansion will be easier for countries with developed high-speed internet infrastructure on the ground.

- The economic feasibility is expected to be the greatest in Korea, which is the first in the world to commercialize 5G and leads 6G-related technologies.

● Free space optical communication is an important technology to realize 6G, one of the essential strategic technologies for the country (Ministry of Science and ICT 2020), and is expected to be a representative technology in which spin-off and spin-in between space technology and industrial technology are actively taking place.

- Space optical communication is directly or indirectly related to four technologies among the 10 essential national strategic technologies selected and announced in 2021, including aerospace, 6G, quantum, and cyber security, and corresponds to the privately led space industry.

- Domestic space optical communication technology is now in its infancy, but high economic feasibility and rapid development are expected due to the government's strong will to create a space industry ecosystem led by the private sector, its effectiveness in the satellite information industry, its great ripple effect on the ground industry, and its high-speed Internet infrastructure on the ground. field