Ground equipment

Abstract

To secure an environment of communication between a monitoring satellite and a ground facility in a satellite group which flies in an earth orbit.SOLUTION: A communication satellite group 44, formed of infrastructure satellites which each fly in an earth orbit (LEO), flies, in a substantially equal arrangement, an orbit that has an orbital altitude and an orbital inclination for forming a sun-synchronous orbit for orbiting an integral number of times per day. The communication satellite group 44 comprises: a first satellite 61 which communicates with a ground facility 701; a second satellite 62 which communicates with a monitoring satellite 521; and a third satellite 63 which communicates only with the communication satellites flying immediately ahead and behind. The monitoring satellite 521b and the ground facility 701 carry out transmission and reception of information therebetween via the communication satellite group 44. The ground facility 701 is installed at a latitude 60° or more and communicates with the first satellite 61 in every circulation.SELECTED DRAWING: Figure 14

Description

Technical Field

[0001] The present disclosure relates to ground facilities, communication satellites, component satellites, artificial satellites, communication satellite constellations, satellite constellations, and satellites.

Background Art

[0002] Satellite-based social infrastructure such as information exchange with remote or border areas via communication satellites, weather forecasting using images of the meteorological satellite Hinode, and utilization of geospatial information by quasi-zenith positioning satellites has become established in social life. These groups of practical satellites have become critical infrastructure indispensable for social life. On the other hand, due to factors such as debris collisions caused by an increase in the number of objects in the space environment, dangerous events accompanied by the risk of failure or loss of critical infrastructure are increasing. Therefore, there is a need for a mechanism to monitor critical infrastructure and take risk avoidance actions if necessary.

[0003] Patent Document 1 discloses a method for observing space debris in a space where sunlight is backlit.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] In a group of satellites flying in a low Earth orbit (LEO), when an emergency situation requiring immediate response occurs, if an infrastructure satellite is flying on the far side of the Earth, there is a problem that the communication environment with the monitoring center cannot be ensured. Note that the low Earth orbit is, for example, an orbit with an orbital altitude of 500 km or more and 2000 km or less. LEO is an abbreviation for Low Earth Orbit. Patent Document 1 does not disclose a method for monitoring critical infrastructure in a low Earth orbit.

[0006] The present disclosure aims to ensure the communication environment between a monitoring satellite and a monitoring center in a group of satellites flying in a low Earth orbit.

Means for Solving the Problems

[0007] According to the present disclosure A critical infrastructure, which is a social infrastructure in space, is composed of a group of infrastructure satellites flying in a low Earth orbit (LEO: Low Earth Orbit) with an orbital altitude of 500 km or more and 2000 km or less, A group of monitoring satellites flying in an orbit with an orbital altitude of 2000 km or less to monitor the group of infrastructure satellites and perform on-orbit services, Ground facilities installed on the ground to exchange information with each infrastructure satellite of the group of infrastructure satellites, A monitoring center installed on the ground to exchange information with the monitoring satellites are provided, The group of infrastructure satellites includes a group of communication satellites, The group of communication satellites Fly in an evenly arranged orbit having an orbital altitude and an orbital inclination angle that result in a sun-synchronous orbit that makes integer revolutions per day, The communication satellites Communicate with communication satellites flying before and after, The group of communication satellites a first satellite that communicates with the above-ground equipment; a second satellite that communicates with the monitoring satellite; a third satellite that only communicates with a communication satellite flying back and forth; and includes the monitoring satellite and the monitoring center In the ground equipment used in the satellite monitoring system that exchanges information via the communication satellite group, It is installed at a latitude of 60° or more and communicates with the first satellite once a week.

Advantages of the Invention

[0008] In the ground equipment used in the satellite monitoring system according to the present disclosure, the ground equipment is installed at a latitude of 60° or more and communicates with the first satellite once a week. By installing the ground equipment at a high latitude, even if the rotation period of the earth and the revolution period of the orbital plane are different, there is an effect that communication with the ground equipment can be achieved every time the communication satellite orbits the earth.

Brief Description of the Drawings

[0009]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Figure 10

Figure 11

Figure 12

Figure 13

Figure 14

Figure 15

Figure 16

Figure 17

Figure 18

Figure 19

Figure 20

Figure 21

Figure 22

Figure 23

Figure 24

Figure 25

Figure 26

Figure 27

Figure 28

Figure 29

Figure 30

Figure 31

Figure 32

Figure 33

Mode for Carrying Out the Invention

[0010] Hereinafter, embodiments of the present disclosure will be described with reference to the drawings. In each figure, the same or corresponding parts are denoted by the same reference numerals. In the description of the embodiments, the description of the same or corresponding parts will be omitted or simplified as appropriate. Also, in the following drawings, the size relationships of the respective configurations may be different from the actual ones. Further, in the description of the embodiments, directions or positions such as "upper", "lower", "left", "right", "front", "rear", "front side", and "back side" may be indicated. Those notations are merely for convenience of explanation and do not limit the arrangement and orientation of the configurations such as devices, instruments, or parts.

[0011] Embodiment 1. ***Explanation of the overall configuration of the satellite monitoring system 500*** FIG. 1 is a diagram showing an example of the overall configuration of the satellite monitoring system 500 according to the present embodiment. The satellite monitoring system 500 includes a group of monitoring satellites 52 that monitor the critical infrastructure 51 and a monitoring center 53. The satellite monitoring system 500 may also include the critical infrastructure 51 in addition to the group of monitoring satellites 52 and the monitoring center 53. The monitoring satellite 521 is also referred to as a monitoring satellite or a monitoring device.

[0012] The critical infrastructure 51 is infrastructure in space. Specific examples of the critical infrastructure 51 are formed by a group of satellites that make up the following types of social infrastructure. · Information exchange with remote or border areas via communication satellites · Weather forecasting using images from the meteorological satellite Himawari · Utilization of geospatial information by quasi-zenith positioning satellites Also, the satellites that make up the critical infrastructure 51 are referred to as infrastructure satellites 511.

[0013] The group of monitoring satellites 52 is composed of monitoring satellites 521 that monitor the infrastructure satellites 511 that make up the critical infrastructure 51. The monitoring center 53 is installed on the ground and exchanges information with the monitoring satellites 521 of the group of monitoring satellites 52. The monitoring satellites 521 of the group of monitoring satellites 52 and the monitoring center 53 exchange information via a communication device provided in the infrastructure satellite 511.

[0014] The group of satellites that make up the critical infrastructure 51 includes as infrastructure satellites 511 satellites equipped with communication devices that communicate with the monitoring center 53. The infrastructure satellite 511 includes all or part of the communication satellite 401, data relay satellite 402, meteorological satellite 403, observation satellite 404, first observation and monitoring satellite 405, positioning satellite 406, second observation and monitoring satellite 407, space base 408, lunar and planetary exploration satellite 409, exploration satellite 410, and transporter 411. The exploration satellite 410 is an exploration satellite that explores other planets or resources other than the moon. The first observation and monitoring satellite 405 is a satellite equipped in a high orbit such as a geostationary orbit or Molniya orbit, and performs wide-area observation or monitoring on the ground. The second observation and monitoring satellite 407 is an observation or monitoring satellite for collecting various important image information such as large-scale disasters.

[0015] In addition, ground facilities 54 for each infrastructure corresponding to the critical infrastructure 51 are installed on the ground. The ground facilities 54 for each infrastructure are an example of ground facilities installed on the ground and performing information exchange with each infrastructure satellite of the infrastructure satellite group 510.

[0016] Due to factors such as debris collisions caused by an increase in the number of objects in the space environment, dangerous events accompanied by the risk of failure or loss of the critical infrastructure 51 are increasing. Therefore, there is a need for a mechanism to monitor the critical infrastructure 51 and take risk avoidance actions if necessary.

[0017] The monitoring satellite group 52 includes the infrastructure satellite 511 equipped with a communication device for communicating with the monitoring center 53 as the monitoring satellite 521. The monitoring satellite 521 includes all or part of the optical monitoring satellite 421, the radio monitoring satellite 423, the infrared monitoring satellite 422, the service satellite 424, and the debris removal satellite 425. The optical monitoring satellite 421 monitors the infrastructure satellite 511 using an optical system. The radio monitoring satellite 423 monitors the infrastructure satellite 511 using radio waves. The infrared monitoring satellite 422 monitors the infrastructure satellite 511 using infrared detection. The service satellite 424 performs on-orbit services for the infrastructure satellite 511. The debris removal satellite 425 removes debris.

[0018] On-orbit services include all or part of capture, inspection, repair, fuel replenishment, movement, orbit departure (ADR: Active Debris Removal), and laser irradiation.

[0019] The monitoring service provided by the monitoring satellite group 52 is easy to understand when considered in analogy to the roles of eyes, ears, hands, and mouth. To achieve the purpose of visually monitoring the critical infrastructure 51 with a satellite, a method of visually monitoring suspicious objects such as debris using an optical telescope or radar image is effective. Also, a method of monitoring an abnormal temperature environment using infrared detection is effective.

[0020] In addition, the monitoring service of listening with ears has the purpose of monitoring radio waves in outer space where sound waves do not propagate. To achieve the purpose of auditorily monitoring the critical infrastructure 51 with a satellite, a method of receiving radio waves flying around and monitoring the radio wave situation that may cause malfunction is effective.

[0021] In addition, as an extended service for monitoring, on-orbit services can be cited as an analogy to the role of manual operation. Examples of on-orbit services include services such as capturing, inspecting, and repairing malfunctioning satellites. Also included are services such as refueling satellites that have run out of fuel, mobile services that move the position of the service, and active debris removal (ADR) of satellites that are unable to leave orbit on their own after the end of their lifespan. Additionally, services that irradiate lasers to monitor the distance to suspicious objects such as debris are also included.

[0022] Thus, it is expected that the monitoring satellite 521 will realize the roles of the eyes, ears, or hands. However, there are limitations to the role of the mouth, that is, the communication means for transmitting the monitoring information 590, and thus ingenuity is required.

[0023] In this embodiment, the infrastructure satellite 511 is used as the monitoring satellite 521 that plays the role of the mouth, that is, the monitoring satellite 521 that transmits the monitoring information 590. The monitoring satellite 521 includes the infrastructure satellite 511 as the monitoring satellite 521 that plays the role of the mouth. Also, the infrastructure satellite 511 includes the monitoring satellite 521 that plays the role of the mouth. That is, in the satellite monitoring system 500, there exists a satellite that is both the monitoring satellite 521 and the infrastructure satellite 511. Here, such a satellite has been mainly described as the infrastructure satellite 511 that plays the role of the mouth, but it may also be a satellite that plays the roles of the eyes, ears, and hands.

[0024] As shown in FIG. 1, the monitoring satellite 521 that conducts long-distance communication includes the communication satellite 401 and the data relay satellite 402 in the first satellite group 601. Also included is the communication satellite 401 in the second satellite group 602. Also included is the lunar planetary exploration satellite 409 in the third satellite group 603. The monitoring satellite 521 that conducts short-distance communication includes the meteorological satellite 403, the positioning satellite 406, and the observation satellite 404 in the first satellite group 601.

[0025] As shown in FIG. 1, the satellite monitoring system 500 includes a first satellite group 601, a second satellite group 602, a third satellite group 603, and a monitoring center 53. The first satellite group 601 is composed of a group of satellites flying near the geostationary earth orbit (GEO) or near the quasi-zenith orbit (QZO). The second satellite group 602 is composed of a group of satellites flying near the medium earth orbit (MEO) or near the low earth orbit (LEO). The third satellite group 603 is composed of a group of satellites flying in the cis-lunar space, which is the space between the moon and the earth, or beyond the moon.

[0026] FIG. 2 is a configuration example of the monitoring center 53 according to the present embodiment. The monitoring center 53 is also referred to as ground equipment 701 installed on the ground. Here, it will be described as the ground equipment 701.

[0027] The ground equipment 701 includes a computer. The ground equipment 701 includes a processor 910 and other hardware such as a memory 921, an auxiliary storage device 922, an input interface 930, an output interface 940, and a communication device 950. The processor 910 is connected to the other hardware via signal lines and controls these other hardware.

[0028] As an example of functional elements, the ground equipment 701 includes a monitoring management unit 710 and a storage unit 720. The monitoring information 590 is stored in the storage unit 720.

[0029] The function of the monitoring management unit 710 is realized by software. The storage unit 720 is provided in the memory 921. Alternatively, the storage unit 720 may be provided in the auxiliary storage device 922. Also, the storage unit 720 may be provided separately in the memory 921 and the auxiliary storage device 922.

[0030] The ground facility 701 exchanges monitoring information 590 with the monitoring satellite 521 via the infrastructure satellite 511. The monitoring management unit 710 uses the monitoring information 590 exchanged with the monitoring satellite 521 to realize a function of coping with the risk of failure or loss of the critical infrastructure 51. For example, the monitoring management unit 710 realizes functions such as danger warning, danger prevention, or danger avoidance in the critical infrastructure 51.

[0031] The processor 910 is a device that executes a monitoring management program. The monitoring management program is a program that realizes the functions of each component of the ground facility 701 and the satellite monitoring system 500.

[0032] The processor 910 is an IC (Integrated Circuit) that performs arithmetic processing. Specific examples of the processor 910 are a CPU, a DSP (Digital Signal Processor), and a GPU (Graphics Processing Unit).

[0033] The memory 921 is a storage device that temporarily stores data. Specific examples of the memory 921 are an SRAM (Static Random Access Memory) or a DRAM (Dynamic Random Access Memory). The auxiliary storage device 922 is a storage device that stores data. A specific example of the auxiliary storage device 922 is an HDD. Also, the auxiliary storage device 922 may be a portable storage medium such as an SD (registered trademark) memory card, a CF, a NAND flash, a flexible disk, an optical disk, a compact disk, a Blu-ray (registered trademark) disk, or a DVD. Note that HDD is an abbreviation for Hard Disk Drive. SD (registered trademark) is an abbreviation for Secure Digital. CF is an abbreviation for CompactFlash (registered trademark). DVD is an abbreviation for Digital Versatile Disk.

[0034] The input interface 930 is a port connected to an input device such as a mouse, a keyboard, or a touch panel. Specifically, the input interface 930 is a USB (Universal Serial Bus) terminal. Note that the input interface 930 may be a port connected to a LAN (Local Area Network). The output interface 940 is a port to which a cable of a display device 941 such as a display is connected. Specifically, the output interface 940 is a USB terminal or an HDMI (registered trademark) (High Definition Multimedia Interface) terminal. Specifically, the display is an LCD (Liquid Crystal Display).

[0035] The communication device 950 has a receiver and a transmitter. Specifically, the communication device 950 is a communication chip or a NIC (Network Interface Card).

[0036] The monitoring management program is loaded into the processor 910 and executed by the processor 910. In the memory 921, not only the monitoring management program but also an OS (Operating System) is stored. While executing the OS, the processor 910 executes the monitoring management program. The monitoring management program and the OS may be stored in an auxiliary storage device. The monitoring management program and the OS stored in the auxiliary storage device are loaded into the memory 921 and executed by the processor 910. Note that part or all of the monitoring management program may be incorporated into the OS.

[0037] The ground facility 701 may include a plurality of processors that replace the processor 910. These plurality of processors share the execution of the monitoring management program. Each processor is a device that executes the monitoring management program in the same manner as the processor 910.

[0038] Data, information, signal values, and variable values used, processed, or output by the monitoring management program are stored in the memory 921, auxiliary storage device 922, or registers or cache memory within the processor 910.

[0039] The "section" of the monitoring management unit 710 may be read as "process", "procedure", or "step". Also, the "processing" of the monitoring management process may be read as "program", "program product", or "computer-readable storage medium storing a program". The monitoring management program causes a computer to execute each process, each procedure, or each step obtained by reading the "section" of the monitoring management unit as "process", "procedure", or "step". Also, the monitoring management method is a method performed when the ground facility 701 executes the monitoring management program. The monitoring management program may be stored and provided in a computer-readable recording medium or storage medium. Also, the monitoring management program may be provided as a program product.

[0040] Also, the processor may be replaced by an electronic circuit. Each of the processor and the electronic circuit is also called a processing circuitry. That is, the functions of each device of the satellite monitoring system 500 are realized by the processing circuitry.

[0041] FIG. 3 is a configuration example of a satellite 30, which is an example of a celestial object according to the present embodiment. The satellite 30 includes a satellite control device 310, a communication device 32, a propulsion device 33, an attitude control device 34, and a power supply device 35. In addition, it includes components for realizing various functions. In FIG. 3, the satellite control device 310, the communication device 32, the propulsion device 33, the attitude control device 34, and the power supply device 35 will be described. The satellite 30 is an example of a celestial object.

[0042] The satellite control device 310 is a computer that controls the propulsion device 33 and the attitude control device 34, and includes a processing circuit. Specifically, the satellite control device 310 controls the propulsion device 33 and the attitude control device 34 according to various commands transmitted from the ground device. The satellite communication device 32 is a device that communicates with ground facilities or a ground device. Specifically, the communication device 32 transmits various data related to the satellite to the ground device. Also, the communication device 32 receives various commands transmitted from the ground device. The propulsion device 33 is a device that applies a propulsion force to the satellite 30 and changes the speed of the satellite 30. Specifically, the propulsion device 33 is an apogee kick motor or a chemical propulsion device, or an electric propulsion device. The apogee kick motor (AKM) is the upper-stage propulsion device used for launching artificial satellites, and is also called an apogee motor (when using a solid rocket motor) or an apogee engine (when using a liquid engine). The chemical propulsion device is a thruster using a mono-liquid or bi-liquid fuel. As the electric propulsion device, there are an ion engine or a Hall thruster. The apogee kick motor is the name of the device used for orbit transfer, and may also be a type of chemical propulsion device. The attitude control device 34 is a device for controlling attitude elements such as the attitude of the satellite 30, the angular velocity of the satellite 30, and the line of sight direction. The attitude control device 34 changes each attitude element in a desired direction. Or, the attitude control device 34 maintains each attitude element in a desired direction. The attitude control device 34 includes an attitude sensor, an actuator, and a controller. The attitude sensor is a device such as a gyroscope, an earth sensor, a sun sensor, a star tracker, a thruster, and a magnetic sensor. The actuator is a device such as an attitude control thruster, a momentum wheel, a reaction wheel, and a control moment gyro. The controller controls the actuator according to the measurement data of the attitude sensor or various commands from the ground device. The power supply device 35 includes devices such as a solar cell, a battery, and a power control device, and supplies power to each device mounted on the satellite 30.

[0043] The processing circuit provided in the satellite control device 310 will be described. The processing circuit may be dedicated hardware or a processor that executes a program stored in a memory. In the processing circuit, some functions may be realized by dedicated hardware and the remaining functions may be realized by software or firmware. That is, the processing circuit can be realized by hardware, software, firmware, or a combination thereof. Specifically, the dedicated hardware is a single circuit, a composite circuit, a programmed processor, a parallel-programmed processor, an ASIC, an FPGA, or a combination thereof. ASIC is an abbreviation for Application Specific Integrated Circuit. FPGA is an abbreviation for Field Programmable Gate Array.

[0044] FIG. 4 is a diagram showing a configuration example of the communication satellite 401 according to the present embodiment. FIG. 5 is a diagram showing a configuration example of the observation satellite 404 according to the present embodiment. FIG. 6 is a diagram showing another example of the configuration of the observation satellite 404 according to the present embodiment. In FIGS. 3 to 6, components with the same name have the same functions and their descriptions may be omitted.

[0045] Based on FIG. 4, the configuration of the communication satellite 401 will be described. The communication satellite 401 includes a communication device 121, a propulsion device 122, a power supply device 123, and a camera 124. For example, the camera 124 is a wide-angle camera that points in the same direction as the pointing direction of the first directional antenna 121E or the second directional antenna 121W.

[0046] The communication satellite 401 can visually capture an observation satellite and other space objects flying in a geostationary orbit or an orbit near the geostationary orbit. Therefore, it is possible to visually confirm that there are no obstacles around the communication satellite 401 that cause interference and noise due to communication. The other space objects are different from the space objects observed by the observation satellite.

[0047] By arranging the camera 124 so that the direction from the communication satellite 401 to the Earth becomes the line-of-sight vector, the observation satellite 404 and other space objects flying in a geostationary orbit or an orbit near the geostationary orbit can be visually captured. Furthermore, it becomes possible to estimate the positions of other space objects on the orbit. Therefore, it is possible to visually confirm that there is no interference and noise due to communication around the communication satellite 401.

[0048] Based on FIG. 5, the configuration of the observation satellite 404 will be described. The observation satellite 404 includes an observation device 111, a satellite control device 112, a communication device 113, a propulsion device 114, an attitude control device 115, a power supply device 116, and a camera 117. The observation device 111 is a device for observing space objects. The observation device 111 is also called monitoring equipment. The camera 117 is, for example, a wide-angle camera that points to the communication satellite 401.

[0049] The camera 117 can visually capture the communication satellite 401 and other space objects flying in a geostationary orbit or an orbit near the geostationary orbit. Therefore, it is possible to visually confirm that there is no interference and noise due to communication around the observation satellite 404.

[0050] The camera 117 is arranged so that the direction from the observation satellite 404 to the communication satellite 401 becomes the line-of-sight vector, whereby the communication satellite 401 and other space objects flying in a geostationary orbit or an orbit near the geostationary orbit can be visually captured. Furthermore, it becomes possible to estimate the positions of other space objects on the orbit. For this reason, it is possible to visually confirm that the environment around the observation satellite 404 is free from communication interference and noise.

[0051] Based on FIG. 6, another example of the configuration of the observation satellite 404 will be described. The observation satellite 404 includes an observation device 201, a satellite control device 202, a communication device 203, a propulsion device 204, an attitude control device 205, and a power supply device 206.

[0052] The observation device 201 is a device for observing space objects. The observation device 201 is a device for detecting space objects with an optical system. The observation device 201 photographs space objects flying at an altitude different from the orbital altitude of the observation satellite with an optical system. Specifically, the observation device 201 is a visible optical sensor. The observation device 201 generates observation data. The observation data is data obtained by the observation performed by the observation device 201. For example, the observation data corresponds to data representing an image in which a space object is reflected.

[0053] The satellite control device 202 is a computer that controls the observation satellite 404. The satellite control device 202 controls the observation device 201, the propulsion device 204, and the attitude control device 205 according to a predetermined procedure or various commands transmitted from ground facilities.

[0054] The communication device 203 is a device that communicates with ground facilities. It is also called a satellite communication device. The communication device 203 transmits, for example, observation data to ground facilities. Also, the communication device 203 receives, for example, various commands transmitted from ground facilities.

[0055] ***Explanation of the Configuration and Operation of the Satellite Monitoring System 500*** In this embodiment, mainly, the configuration and operation of the satellite monitoring system 500 in the second satellite group 602 shown in FIG. 1 will be described.

[0056] <Overall configuration example of the satellite monitoring system 500> In this embodiment, the critical infrastructure 51 is a social infrastructure in space. The critical infrastructure 51 is composed of an infrastructure satellite group 510 consisting of infrastructure satellites 511 flying in a low Earth orbit (LEO) with an orbital altitude of 500 km or more and 2000 km or less. The monitoring satellite group 52 consists of monitoring satellites 521 flying in an orbit with an orbital altitude of 2000 km or less, monitoring the infrastructure satellite group 510 and performing on-orbit services. The ground facility 54 for each infrastructure is an example of a ground facility installed on the ground and performing information exchange with each infrastructure satellite 511 of the infrastructure satellite group 510. The monitoring center 53 is an example of a ground facility installed on the ground and performing information exchange with the monitoring satellite 521.

[0057] As shown in FIG. 1, the infrastructure satellite group 510 includes a communication satellite group 44 consisting of communication satellites 401.

[0058] The communication satellite group 44 flies in an orbit having an orbital altitude and an orbital inclination angle that form a sun-synchronous orbit that makes an integer number of revolutions per day, with a substantially uniform arrangement. The communication satellite 401 communicates with the communication satellites flying before and after it. The communication satellite group 44 includes a first satellite 61 that communicates with a ground facility such as the ground facility 54 for each infrastructure, a second satellite 62 that communicates with the monitoring satellite 521b, and a third satellite 63 that only performs communication with the communication satellites flying before and after it. The monitoring satellite 521b and the monitoring center 53 perform information exchange via the communication satellite group 44.

[0059] FIG. 7 is a diagram showing a configuration example of the satellite monitoring system 500 according to the present embodiment. In FIG. 7, the monitoring satellite 521b that plays the role of the ear is the infrastructure satellite 511, and communicates with the communication satellite 401 that is the monitoring satellite playing the role of the mouth. The communication satellite 401 that communicates with the monitoring satellite 521b is an example of the second satellite 62. Here, the monitoring satellite 521b that plays the role of the ear may be the monitoring satellite 521a that plays the role of the eye, or the monitoring satellite 521c that plays the role of the hand. The monitoring satellite 521b that plays the role of the ear and the communication satellite 401 which is an example of the second satellite 62 are provided with a second communication device 42 for communication between infrastructure satellites.

[0060] The communication satellite 401 which is an example of the first satellite 61 is provided with a first communication device 41 for communicating with ground facilities. Further, the communication satellite 401 which is an example of the first satellite 61 is also provided with a second communication device 42 for communication between infrastructure satellites.

[0061] The communication satellite 401 which is an example of the third satellite 63 that only communicates with communication satellites flying back and forth is provided with a second communication device 42 for communication between infrastructure satellites.

[0062] In the group of satellites flying in LEO, when an emergency situation requiring emergency response occurs even when the infrastructure satellite 511 is flying on the back side of the earth, there may be a case where the communication environment with the monitoring center 53 cannot be ensured. However, according to the satellite monitoring system 500 according to the present embodiment, it has an environment in which a plurality of communication satellites communicate with each other, and monitoring information can be exchanged via the plurality of communication satellites from the back side of the earth. Therefore, there is an effect that the monitoring information can be exchanged with the monitoring center at any time and anywhere. For this reason, when a dangerous space object such as debris approaches the infrastructure satellite 511, there is an effect that it can immediately take a danger avoidance action.

[0063] <Configuration Example 1 of Communication Satellite Group 44> Each communication satellite 401 in the communication satellite group 44 flies in a sun-synchronous orbit with an orbital altitude of approximately 1,666 km and makes 12 orbits per day. The communication satellite group 44 is composed of five or more communication satellites 401.

[0064] When the orbital altitude is about 1,666 km and it makes 12 orbits per day, and the orbital inclination angle is set to 77° (180° - 103°), it becomes a sun-synchronous orbit. When five satellites fly in this orbit with an equal phase, the radius of the inscribed circle of the formed pentagon is larger than the radius of the Earth, so the communication field of view between the satellites can be ensured. Assuming that the altitude at which the influence of the atmosphere can be ignored is 300 km, if there are six or more satellites, there is an effect that a communication line can be ensured at an altitude of 585 km or more above the ground surface. Also, since it revisits the same latitude at the same time every day, every two hours, there is an effect that information can be exchanged between the ground facilities at a frequency of every two hours at a fixed time every day.

[0065] <Configuration Example 2 of Communication Satellite Group 44> Each communication satellite 401 in the communication satellite group 44 flies in a sun-synchronous orbit with an orbital altitude of approximately 1,248 km and makes 13 orbits per day. The communication satellite group 44 is composed of six or more communication satellites.

[0066] When the orbital altitude is about 1,248 km and it makes 13 orbits per day, and the orbital inclination angle is set to 79° (180° - 101°), it becomes a sun-synchronous orbit. When six satellites fly in this orbit with an equal phase, the radius of the inscribed circle of the formed hexagon is larger than the radius of the Earth, so the communication field of view between the satellites can be ensured. Assuming that the altitude at which the influence of the atmosphere can be ignored is 300 km, if there are seven or more satellites, there is an effect that a communication line can be ensured at an altitude of 491 km or more above the ground surface. Since it revisits the same latitude at the same time every day, every 111 minutes, there is an effect that information can be exchanged between the ground facilities at a frequency of every 111 minutes at a fixed time every day.

[0067] <Configuration Example 3 of Communication Satellite Group 44> Each communication satellite 401 in the communication satellite group 44 orbits in a sun-synchronous orbit at an orbital altitude of approximately 881 km, completing 14 orbits per day. The communication satellite group 44 is composed of seven or more communication satellites.

[0068] FIG. 8 is a diagram showing Configuration Example 3 of the communication satellite group 44 according to the present embodiment. When the orbital altitude is approximately 881 km and the orbital inclination angle is set to 81° (180° - 99°) and it orbits 14 times a day, it becomes a sun-synchronous orbit. If the orbital parameters for sun-synchronization at an orbital altitude of 881 km are set, an orbit that completes 14 orbits per day can be realized. When seven satellites fly in this orbit with an equal phase, the radius of the inscribed circle of the formed hexagon is larger than the radius of the Earth, so a communication field of view between the satellites can be ensured. Assuming that the altitude at which the influence of the atmosphere can be ignored is 300 km, if there are eight or more satellites, there is an effect that a communication line can be secured at an altitude of 327 km or more above the ground surface.

[0069] Since it revisits the same latitude at the same time every day, every 103 minutes, there is an effect that information can be exchanged between ground facilities at a fixed time every day at a frequency of every 103 minutes. Note that the orbital inclination angle of 77° is the same as 103° depending on the definition. Also, the orbital inclination angle of 79° is the same as 101° depending on the definition. Also, the orbital inclination angle of 81° is the same as 99° depending on the definition.

[0070] <Configuration Example 4 of the communication satellite group 44> The communication satellite group 44 is in a sun-synchronous orbit and is composed of satellite groups in two orbital planes of LST 9:00 and LST 15:00. LST is an abbreviation for Local Sun Time.

[0071] FIG. 9 is a diagram showing Configuration Example 4 of the communication satellite group 44 according to the present embodiment. Sun-synchronous orbits are frequently used in Earth observation satellites. In optical satellites, the vicinity of LST 10:30 and LST 13:30 with good sunlight conditions is frequently used. Also, in radar satellites, LST 06:00 and LST 18:00, which are advantageous for solar power generation, are frequently used. When the orbital altitude of the communication satellite is 881 km, the inscribed circle of a regular octagon is 6727 km, so a communication line can be secured with any LST monitoring satellite. Note that the monitoring satellite may be a user satellite that uses the communication satellite group 44 as a communication line. Therefore, if communication satellites are deployed in two orbital planes at LST 09:00 and LST 15:00, there is an effect that communication can be achieved with all of the satellite groups frequently used for earth observation.

[0072] <Communication method of communication satellite group 44> FIG. 10 is a diagram showing the communication method of the communication satellite group 44 according to the present embodiment. The communication satellite 401 and the monitoring satellite 521 include a bidirectional communication terminal 65 provided with a transmission / reception switching device 64 that realizes reception and transmission by switching between a reception function and a transmission function. The ground facility 701, which is the monitoring center 53, operates the transmission / reception switching device 64 based on the data amount α of the command transmitted to the monitoring satellite 521 and the data amount β of the monitoring data and telemetry received from the monitoring satellite 521, so that the reception time and transmission time ratio of the monitoring satellite 521 is α to β. Specifically, the ground facility 701 operates the transmission / reception switching device 64 based on the data amount α of the command transmitted to the monitoring satellite 521 and the data amount β of the monitoring report data received from the monitoring satellite 521, so that the ratio of the reception operation time when the reception function operates and the transmission operation time when the transmission function operates in the bidirectional communication terminal 65 is α to β. The monitoring satellite 521 and the ground facility 701 exchange information via the communication satellite 401.

[0073] In the present embodiment, a configuration example in which a command and monitoring report data are exchanged between the monitoring satellite and the monitoring center has been described. However, the monitoring satellite may be another user satellite that uses the communication satellite group 44 as a communication line.

[0074] Embodiment 2. In this embodiment, mainly, the points added to or different from those in Embodiment 1 will be described. Note that the same components as those in Embodiment 1 may be denoted by the same reference numerals, and the description thereof may be omitted.

[0075] In Embodiment 1, mainly, the configuration in which the monitoring satellite 521 and the monitoring center 53 perform information exchange via the communication satellite group 44 included in the infrastructure satellite group 510 was described. In this embodiment, a satellite information transmission system 501 in which the user satellite 531 and the ground facility 702 perform information exchange via the communication satellite group 44 included in the infrastructure satellite group 510 will be described.

[0076] FIG. 11 is a diagram showing a configuration example of the satellite information transmission system 501 according to this embodiment. FIG. 12 is a diagram showing an overall configuration example of the satellite information transmission system 501 according to this embodiment. The basic configuration of the satellite information transmission system 501 is the same as that of the satellite monitoring system 500 described in Embodiment 1. The satellite information transmission system 501 is similar to the satellite monitoring system 500 described in Embodiment 1, in which the monitoring satellite 521 is replaced with the user satellite 531 and the monitoring center 53 is replaced with the ground facility 702.

[0077] In FIGS. 11 and 12, the first satellite 61 that communicates with the ground facility 702 is represented by "first", the second satellite 62 that communicates with the user satellite 531 is represented by "second", and the third satellite 63 that only communicates with the communication satellites flying before and after is represented by "third".

[0078] The satellite information transmission system 501 includes a critical infrastructure 51 composed of an infrastructure satellite group 510 flying in LEO and a ground facility 702 that exchanges information with each infrastructure satellite of the infrastructure satellite group 510. The infrastructure satellite group 510 is composed of a communication satellite group 44 and a user satellite group 530 composed of user satellites 531 that use the communication satellite group 44 as a communication line.

[0079] As shown in FIGS. 11 and 12, the communication satellite group 44 flies in an orbit having an orbital altitude and an orbital inclination angle that result in an integer number of orbits around the sun per day, with the orbits being arranged approximately evenly. The communication satellite 401 communicates with the communication satellites flying before and after it. The communication satellite group 44 includes a first satellite 61 that communicates with the ground facility 702, a second satellite 62 that communicates with the user satellite 531, and a third satellite 63 that only communicates with the communication satellites flying before and after it. The user satellite 531 and the ground facility 702 exchange information via the communication satellite group 44.

[0080] <Configuration Examples 1 to 4 of the Communication Satellite Group 44> Also, regarding the configuration example of the communication satellite group 44 according to the present embodiment, it is possible to apply the same configuration as that of Configuration Examples 1 to 4 of the communication satellite group 44 described in the embodiment.

[0081] <Communication Method of the Communication Satellite Group 44> Regarding the communication method of the communication satellite group 44 according to the present embodiment, it is also possible to apply the same communication method as the communication method of the communication satellite group 44 described in the embodiment.

[0082] FIG. 13 is a diagram showing the communication method of the communication satellite group 44 according to the present embodiment. The communication satellite 401 and the user satellite 531 are equipped with a bidirectional communication terminal 65 having a transmission / reception switching device 64. The ground facility 702 operates the transmission / reception switching device 64 based on the data volume α of the command transmitted to the user satellite 531 and the data volume β of the user information data received from the user satellite 531, so that the reception time to transmission time ratio of the user satellite 531 is α to β. The user satellite 531 and the ground facility 702 exchange information via each communication device of the communication satellite group 44.

[0083] Embodiment 3. In this embodiment, mainly, the points added to or different from those in Embodiments 1 and 2 will be described. Note that the same components as those in Embodiments 1 and 2 may be denoted by the same reference numerals, and the description thereof may be omitted.

[0084] <Ground facilities> In this embodiment, the ground facilities used in the satellite monitoring system 500 or the satellite information transmission system 501 described in Embodiments 1 and 2 will be described. Examples of the ground facilities are the ground facilities 701 of the monitoring center 53, the ground facilities 54 for each infrastructure, or the ground facilities 702 that exchange information with the user satellite 531.

[0085] FIG. 14 is a diagram for explaining the ground facilities according to this embodiment. The ground facilities used in the satellite monitoring system 500 or the satellite information transmission system 501 described in Embodiments 1 and 2 are installed at a latitude of 60° or more and communicate with the "first" of the first satellite 61 once a week.

[0086] The rotation period of the earth and the revolution period of the orbital plane are different. For this reason, when a communication satellite flying in the orbit of LST 09:00 communicates with the ground facilities, for example, the ground facilities installed near the equator may be able to communicate only twice, around AM 09:00 and around PM 09:00. On the other hand, for the ground facilities installed at high latitudes, even if the rotation period of the earth and the revolution period of the orbital plane are different, there is an effect that the communication satellite can communicate with the ground facilities once a week as it orbits the earth.

[0087] <Example 1 of communication satellite> Next, Example 1 of the communication satellite 401 used in the satellite monitoring system 500 or the satellite information transmission system 501 described in Embodiments 1 and 2 will be described.

[0088] FIG. 15 is a diagram for explaining Example 1 of the communication satellite according to this embodiment. In Example 1 of the communication satellite, the communication satellite 401 includes a first communication device 41 that communicates with ground facilities and three second communication devices 42 that communicate between infrastructure satellites. In Example 1 of the communication satellite, the communication satellite 401 communicates with communication satellites flying in the same orbital plane and with a monitoring satellite or a user satellite simultaneously.

[0089] If there is a set of the first communication devices for communicating with ground facilities and three sets of the second communication devices for communicating between infrastructure satellites, it is possible to communicate with communication satellites flying in the same orbital plane and with a monitoring satellite or a user satellite simultaneously. Also, according to the communication satellite according to Example 1 of the communication satellite according to the present embodiment, there is an effect that information communicated with a user satellite can be transmitted to ground facilities in real time. Therefore, even in a situation where the number of satellites flying in the same orbital plane is small during the construction of critical infrastructure, there is an effect that information can be exchanged between a user satellite and ground facilities. Also, since communication terminals can be standardized, there is an effect that the total cost can be reduced.

[0090] <Example 2 of the communication satellite> Next, Example 2 of the communication satellite used in the satellite monitoring system 500 or the satellite information transmission system 501 described in Embodiments 1 and 2 will be described.

[0091] FIG. 16 is a diagram showing an example of the satellite information transmission system 501 according to the present embodiment. In Example 2 of the communication satellite, the communication satellite 401 includes a first communication device 41 that communicates with ground facilities, a second communication device 42 that communicates between infrastructure satellites, and a third communication device 43 that communicates with a monitoring satellite 521 or a user satellite 531.

[0092] FIG. 17 is a diagram for explaining Example 2 of the communication satellite according to the present embodiment. In Example 2 of the communication satellite, the communication satellite 401 is equipped with one set of a first communication device for communicating with ground facilities, two sets of a second communication device for communicating with infrastructure satellites flying before and after the orbital plane, and one set of a third communication device for communicating with a monitoring satellite or a user satellite. As a result, there is an effect that information communicated with the user satellite can be transmitted to the ground facilities in real time. Therefore, even in a situation where the number of satellites flying in the same orbital plane is small during the construction of critical infrastructure, there is an effect that information can be exchanged between the user satellite and the ground facilities. In addition, by using a dedicated terminal for the monitoring satellite or the user satellite, communication is possible even with a small-sized terminal with a small aperture. As a result, there is an effect that the monitoring satellite or the user satellite can be realized as a small satellite.

[0093] Embodiment 4. In this embodiment, mainly, points added to or different from Embodiments 1 to 3 will be described. Note that the same reference numerals are given to the same configurations as those in Embodiments 1 to 3, and the description thereof may be omitted.

[0094] In this embodiment, a monitoring system 502 will be described in which the constituent satellites of the first satellite constellation 810 that monitors the Earth, flying objects, and celestial objects perform information exchange of satellite information with ground facilities via the constituent satellites of the second satellite constellation 820.

[0095] <Overall configuration example of the monitoring system 502> FIG. 18 is a diagram showing a configuration example of the monitoring system 502 according to this embodiment. In the monitoring system 502, the constituent satellite 811 of the first satellite constellation 810 that monitors the Earth, flying objects, and celestial objects performs information exchange of satellite information with ground facilities via the constituent satellite 812 of the second satellite constellation 820.

[0096] The first satellite constellation 810 is a satellite group composed of three or more constituent satellites that cooperate to monitor the Earth, flying objects, and celestial objects. The ground equipment exchanges information with the component satellites that form the first satellite constellation 810. The second satellite constellation 820 consists of a communication satellite group of six or more communication satellites that fly in a substantially evenly distributed sun-synchronous orbit at an orbital altitude of 800 km or more and communicate with satellites flying before and after in the same orbital plane, and relays satellite information in cooperation. That is, the component satellites of the second satellite constellation 820 are a communication satellite group consisting of six or more communication satellites.

[0097] The component satellites that form the first satellite constellation 810 exchange information with the ground equipment via the second satellite constellation 820.

[0098] In recent years, with the emergence of flying objects that glide at supersonic speeds, satellite launching and flight path tracking are expected. However, it may be difficult to establish a constant communication environment in a LEO constellation.

[0099] There is also a technology of exchanging information via a data relay satellite on a geostationary orbit. However, when the number of on-orbit satellites increases and the usage frequency of data relay satellites increases, there may be cases where communication lines cannot be used in emergencies. Also, since information is transmitted from LEO satellites to ground equipment via a geostationary orbit, there may be a time delay.

[0100] In the monitoring system 502 according to this embodiment, information exchange between the first satellite constellation and the ground equipment can be enabled for constant communication via a communication satellite group configured in a low-altitude sun-synchronous orbit. Also, there is an effect that information can be exchanged in a shorter time than via a data relay satellite on a geostationary orbit.

[0101] Also, by increasing the number of satellites in the second satellite constellation, the number of component satellites of the first satellite constellation that can exchange data simultaneously can be increased. Therefore, there is an effect that monitoring data of a large number of monitoring targets can be exchanged simultaneously. In addition, by increasing the number of satellites in the second satellite constellation, the number of ground facilities that can simultaneously exchange data can be increased. Therefore, there is an effect that it becomes possible to take countermeasures against a large number of monitoring targets simultaneously.

[0102] In addition, in order to monitor the Earth, flying objects or space objects with a visible high-resolution optical monitoring device, even when a sun-synchronous orbit satellite is adopted, there is a problem that the time for exchanging information with ground facilities installed at a specific longitude is limited. The same problem existed even when a geostationary data relay satellite was adopted. In the monitoring system 502 according to the present embodiment, by realizing a constant communication environment via a low-orbit communication satellite group, there is an effect that it can be used for emergency response in the event of a disaster or the like.

[0103] Geosynchronous satellites generally use a geostationary orbit, but there is a problem that it is difficult to perform high-resolution monitoring with a geostationary satellite flying at an altitude of 36,000 km. Therefore, if an orbit that orbits the equator multiple times a day is adopted, there is an effect that high-resolution monitoring becomes possible. However, in this case as well, there is a problem that constant communication cannot be performed only with ground facilities installed at a specific longitude. Therefore, there is an effect that a group of geosynchronous satellites capable of constant communication can be realized.

[0104] <Example 1 of the First Satellite Constellation 810> Example 1 of the first satellite constellation 810 is a satellite constellation that orbits an inclined circular orbit with an orbital altitude of 1,000 km or more and 6,000 km or less multiple times a day. The plurality of orbital planes formed by the plurality of component satellites included in the first satellite constellation 810 are shifted by equal angles in the azimuth direction with respect to each other's normals, and the flying positions of each orbital plane are synchronously controlled.

[0105] FIG. 19 is a configuration example of Example 1 of the first satellite constellation 810 according to the present embodiment. Let the number of times each component satellite orbits the Earth in a day be "N". The first satellite constellation 810 includes N component satellites. Each component satellite moves in an inclined circular orbit and orbits the Earth N times a day. The plane formed by the orbit in which each component satellite moves is called the orbital plane. The N orbital planes formed by the N component satellites are such that their normal vectors are shifted by 360 / N degrees each in the azimuth direction. In other words, the relative angles of the azimuth components are shifted by 360 / N degrees each. The azimuth direction corresponds to the direction of travel of the component satellite. That is, the azimuth direction corresponds to the longitude direction, the east-west direction.

[0106] Specifically, the first satellite constellation 810 includes eight component satellites (A to H) and forms eight orbital planes. Each component satellite orbits the Earth eight times a day. The normal vectors of the eight orbital planes are shifted by 45 degrees each in the relative angle of the azimuth component.

[0107] The timings at which the N component satellites (A to H) pass through the northernmost points of their respective orbital planes are synchronized. That is, the N component satellites (A to H) pass through the northernmost points of their respective orbital planes at the same time.

[0108] <Example 2 of the first satellite constellation 810> Example 2 of the first satellite constellation 810 flies in a sun-synchronous non-freezing elliptical orbit with a perigee altitude of 300 km or more and an apogee altitude of 6000 km or less. The plurality of orbital planes formed by the plurality of component satellites included in the first satellite constellation 810 are shifted by equal angles in the azimuth direction components of their major axes.

[0109] FIG. 20 is a configuration example of Example 2 of the first satellite constellation 810 according to the present embodiment. FIG. 20 shows Example 2 of the first satellite constellation 810 as viewed from the normal direction of the orbital plane. The first satellite constellation 810 includes a plurality of component satellites (A to C). Each component satellite orbits in a sun-synchronous elliptical orbit. Each elliptical orbit has a high eccentricity and an orbital inclination angle. That is, the orbit of each component satellite is a sun-synchronous orbit, an inclined orbit, and an elliptical orbit. Also, the elliptical orbit of each component satellite is a non-frozen orbit. That is, the elliptical orbit of each component satellite is not a frozen orbit, and as time passes, the major axis of each elliptical orbit rotates around the Earth within the orbital plane.

[0110] The three component satellites (A to C) alternately monitor the target area of the Earth from the perigee, apogee, or midpoint. The midpoint is a point located between the perigee and the apogee. At the perigee, monitoring can be performed with high resolution although it is for a short time. At the apogee, monitoring can be performed for a long time although it has low resolution.

[0111] The major axis of each of the three elliptical orbits is inclined at equal intervals of approximately 120° each with respect to the circumferential direction of the orbital plane. The azimuth direction corresponds to the longitude direction, that is, the east-west direction. The major axis of each elliptical orbit rotates with respect to the sun 102, but the relative relationship of the three elliptical orbits is maintained.

[0112] <Example 3 of the first satellite constellation 810> In Example 3 of the first satellite constellation 810, it orbits the equatorial orbit multiple times a day, and the flying positions are synchronously controlled with the azimuth direction components shifted by equal angles. In Example 1 of the first satellite constellation 810 in FIG. 19, each component satellite moves in an inclined circular orbit and orbits the Earth N times a day. On the other hand, in Example 3 of the first satellite constellation 810, each component satellite moves in an equatorial orbit and orbits the Earth N times a day. Each component satellite moves in an inclined circular orbit and orbits the Earth N times a day. And the orbital planes in which each component satellite moves have their flying positions synchronously controlled with the azimuth direction components shifted by equal angles.

[0113] <Example 4 of the Second Satellite Constellation> FIG. 21 is a diagram showing a configuration example of Example 4 of the second satellite constellation 820 according to the present embodiment. Example 4 of the second satellite constellation 820 includes a first satellite 61 that communicates with ground facilities, a second satellite 62 that communicates with the constituent satellites that make up the first satellite constellation 810, and a third satellite 63 that only conducts communication with satellites flying before and after.

[0114] <Example 5 of the Second Satellite Constellation> Example 5 of the second satellite constellation 820 is in a sun-synchronous orbit, and a group of six or more communication satellites flying in each orbital plane between LST 09:00 and LST 15:00 cooperate to relay satellite information.

[0115] Sun-synchronous orbits are frequently used for Earth observation satellites. For optical satellites, the vicinity of LST 10:30 and LST 13:30 with good sunlight conditions is frequently used. Also, for radar satellites, LST 06:00 and LST 18:00, which are advantageous for solar power generation, are frequently used. When the orbital altitude of the communication satellite is 881 km, the inscribed circle of a regular octagon is 6727 km, so a communication line with a monitoring satellite at any LST can be ensured. Note that the monitoring satellite may be a user satellite that uses the communication satellite group 44 as a communication line. Therefore, as shown in FIG. 18, if the constituent satellites of the second satellite constellation 820 are deployed in two orbital planes of LST 09:00 and LST 15:00, there is an effect that communication can be made with all of the satellite groups frequently used for Earth observation.

[0116] ***Other Configurations*** The ground facilities of the monitoring system 502 according to the present embodiment may be a moving body. For example, when detecting the launch of a flying body that glides at supersonic speed, it is reasonable to transmit information to a moving body such as an aircraft, UAV (unmanned aerial vehicle), ship, or vehicle that takes direct countermeasures in terms of implementing short-time countermeasures.

[0117] Embodiment 5. In this embodiment, mainly, the points added to or different from Embodiments 1 to 4 will be described. Note that the same components as those in Embodiments 1 to 4 may be denoted by the same reference numerals, and the description thereof may be omitted. In this embodiment, mainly, the communication method of the satellite information transmission system 501 will be described.

[0118] <Example 1 of the communication method of the satellite information transmission system 501> FIG. 22 is a diagram showing a configuration example of the satellite information transmission system 501 according to this embodiment. FIG. 23 is a diagram showing an overall configuration example of the satellite information transmission system 501 according to this embodiment. The satellite information transmission system 501 according to this embodiment relays satellite information between the user satellite 531 that constitutes a group of user satellites orbiting the Earth and the ground facility 702. The satellite information transmission system 501 includes a communication satellite group 44 composed of six or more communication satellites that orbit a sun-synchronous orbit in a low Earth orbit (LEO) with an orbital altitude of 500 km or more and 2000 km or less in a substantially evenly arranged manner and communicate with communication satellites flying before and after in the same orbital plane. The communication satellite 401 communicates with communication satellites flying before and after.

[0119] In Example 1 of the communication method of the satellite information transmission system 501, the communication satellite group 44 includes a first satellite 61 that performs optical communication with the ground facility 702, a second satellite 62 that performs optical communication with the user satellite 531, and a third satellite 63 that only performs communication with communication satellites flying before and after. In the communication satellite group 44, radio communication is performed between communication satellites flying before and after. Optical communication is performed by the optical communication terminal 544. Also, radio communication is performed by the radio communication terminal 542.

[0120] Optical communication has the advantage of enabling high-capacity data transmission. However, since it is necessary to align the optical axes accurately between satellites, both the user satellite and the communication satellite need to perform two-axis high-precision pointing control. Since the relative positions of the ground equipment and the communication satellite vary greatly, it is necessary to perform real-time high-precision control of the pointing direction that changes moment by moment. Also, when the relative positions of the user satellite and the communication satellite vary greatly, it is similarly necessary to perform real-time high-precision control of the pointing direction that changes moment by moment. When the relative position variation is large, the communication available time is also limited, so it is necessary to perform high-capacity communication.

[0121] If a single satellite is to simultaneously achieve all optical communications between the communication satellites before and after, the user satellite, and the ground equipment, it is necessary to perform high-precision optical axis alignment with different targets simultaneously. This poses problems of high technical difficulty and a high risk of communication interruption. In radio wave communication, when realizing high-speed large-capacity data transmission over long distances, it is necessary to align the central axis of the main beam of the radio wave with high precision, similar to the above optical communication. However, in short-range communication, low-speed communication, or communication with a limited amount of data, communication without high-precision axis alignment is also possible using a fixed antenna or an omnidirectional antenna.

[0122] In the communication before and after the communication satellite group according to the above-described embodiment, the distance between the satellites is limited, and moreover, the relative angle variation between the front and rear satellites is small. Therefore, instead of optical communication or high-speed large-capacity radio wave communication that requires high-precision pointing control, radio wave communication using a fixed antenna is also achievable. Furthermore, since communication is always possible, there is an effect that even in low-speed communication, large-capacity communication can be achieved over time. If radio wave communication that does not require high-precision pointing control is used to realize communication between the front and rear satellites, whether the first satellite performs optical communication with the ground equipment or the third satellite performs optical communication with the user satellite, the communication target that requires high-precision pointing control is limited to one at a time. Therefore, there is an effect that the pointing control is easy and the risk of communication interruption can be sufficiently reduced.

[0123] <Example 2 of the communication method of the satellite information transmission system 501> In communication method example 2 of the satellite information transmission system 501, radio waves between communication satellites flying before and after are spread spectrum. When satellites flying before and after on the same orbit communicate by radio waves, there is a problem that there is a risk that a plurality of satellites flying forward or backward may cause radio wave interference or mistransmission. By spreading the spectrum and restoring only the desired satellite signal, there is an effect that radio wave interference or mistransmission can be avoided.

[0124] <Communication method example 3 of satellite information transmission system 501> In communication method example 3 of the satellite information transmission system 501, the communication satellite includes a bidirectional communication terminal 65 with a transmission / reception switching function for communicating with communication satellites flying before and after. If the communication satellite has a transmission terminal to the front satellite and a reception terminal from the rear satellite, and all satellites on the same orbit communicate with the front and rear satellites, it will be established as a satellite information transmission system. However, there is a problem that the risk of communication interruption is high during the maintenance stage of launching the satellite or when a failure occurs in orbit. If it is equipped with a bidirectional communication terminal 65 with a transmission / reception switching function, satellite information transmission will be possible even if not all satellites are in place on the orbit.

[0125] <Communication method example 4 of satellite information transmission system 501> In communication method example 4 of the satellite information transmission system 501, the communication satellite adopts different polarization waves for transmission and reception. Since the relative position and relative attitude with the front and rear communication satellites are maintained, by adopting different polarization waves for transmission and reception, there is an effect that the risk of radio wave interference or mistransmission can be eliminated.

[0126] <Communication method example 5 of satellite information transmission system 501> In communication method example 5 of the satellite information transmission system 501, the communication satellite group 44 includes a fourth satellite that performs optical communication with ground facilities and optical communication with user satellites. Regarding satellite information with urgency, if one satellite can simultaneously transmit and receive information between the user satellite and the ground facility, there is an effect that the delay time can be minimized. Since it is necessary to perform high-precision pointing control for two targets simultaneously, the technical difficulty is high, resulting in a high-cost system. However, if the communication with the front and rear satellites is also optical communication, compared with the case of performing high-precision pointing control for four different targets, it is easier to implement in each stage and has the effect of reducing costs. Also, when there is no urgency, the flying positions where the user satellite and the ground facility can communicate simultaneously are limited. Therefore, if one satellite has the communication function with both parties and communicates in a time-division manner, the targets for simultaneous high-precision pointing control can be limited to one.

[0127] <Example 6 of the communication method of the satellite information transmission system 501> FIG. 24 is a diagram showing Example 6 of the communication method of the satellite information transmission system 501 according to the present embodiment. The fourth satellite 644 shares the optical communication with the ground facility 702 and the optical communication with the user satellite 531 using the same optical communication terminal 544. The fourth satellite 644 rotates around the satellite traveling direction axis and performs the optical communication with the ground facility 702 and the optical communication with the user satellite 531 in a time-division manner.

[0128] Also, when there is no urgency, the flying positions where the user satellite and the ground facility can communicate simultaneously are limited. Therefore, if one satellite has the communication function with both parties and communicates in a time-division manner, the targets for simultaneous high-precision pointing control can be limited to one. Furthermore, standardizing the communication terminals with the user satellite and the ground facility has the effect of reducing costs. This is effective when a sufficient number of communication satellites are flying in orbit and do not deviate from the radio wave field of view even when rotating around the traveling direction axis.

[0129] ***Other configurations*** The ground facility 702 according to the present embodiment may be a moving body. Regarding satellite information with urgency, when it is necessary to transmit from a fixed ground facility to a moving body, directly transmitting the satellite information from the communication satellite to the moving body can suppress the delay time to a minimum. This is effective in cases where a time delay of seconds, such as instructing a countermeasure action after detecting the launch of a flying object, may lead to an increase in risk.

[0130] In addition, the communication satellite group 44 may include a first satellite 61 that communicates with the ground facility 702 via radio waves, a second satellite 62 that communicates with the user satellite 531 via optical communication, and a third satellite 63 that only conducts communication with communication satellites flying before and after. The communication satellite group 44 conducts radio wave communication between communication satellites flying before and after. In optical communication between a communication satellite and a ground facility, there is a problem that communication cannot be performed when there are clouds. For this reason, when the ground facility 701 using the satellite information transmission system of Communication Method Example 1 is in an area with a high cloud cover rate, there is an effect that availability is improved by using radio wave communication.

[0131] Embodiment 6. In this embodiment, mainly, the points added to or different from Embodiments 1 to 5 will be described. Note that the same components as those in Embodiments 1 to 5 may be denoted by the same reference numerals, and the description thereof may be omitted. In this embodiment, mainly, the configurations of a communication satellite constellation, a satellite constellation, and a satellite information transmission system using the satellites flying in the sun-synchronous orbit described in Embodiments 1 to 5 will be described.

[0132] <Configuration of Artificial Satellite 80> FIG. 25 is a diagram showing a configuration example of the artificial satellite 80 according to this embodiment. The artificial satellite 80 according to this embodiment includes a computer or a supercomputer equipped with AI (Artificial Intelligence), and at least one of a cloud server or an edge server as an information processing device 81. The artificial satellite 80 flies in a sun-synchronous orbit at LST 06:00 or LST 18:00. At this time, the artificial satellite 80 has a solar cell directed toward the sunlight incident side, and a heat dissipation surface of the information processing device 81 on the side opposite to the sunlight incident side. The artificial satellite 80 has a solar cell directed toward the sunlight incident side, and on the side opposite to the sunlight incident side, for example, a heat dissipation surface of a computer or an edge server.

[0133] A sun-synchronous orbit is a type of polar orbit that passes over the polar regions. The sun-synchronous orbit has a rotation period around the north-south axis of the orbital plane synchronized with the Earth's revolution period. Therefore, in a sun-synchronous orbit, the solar incidence angle with respect to the orbital plane remains constant throughout the year. Also, in the orbit at LST06:00 or LST18:00, since the normal vector of the orbital plane points in the solar direction, even a low-Earth orbit satellite is constantly irradiated with sunlight without being in the Earth's shadow. Strictly speaking, due to the inclination of the Earth's axis, the normal vector is inclined from the solar direction, but the influence is minor.

[0134] The computers and servers that play the role of the brain in a monitoring satellite are becoming more power-hungry with the advent of AI and the increase in server capacity and speed, and heat dissipation countermeasures are an issue for high-heat-generating devices. The LST06:00 or LST18:00 of the sun-synchronous orbit is also called a dawn-dusk orbit. This dawn-dusk orbit, although it is a low-Earth orbit satellite, does not enter the Earth's shadow and can always generate electricity using solar cells. Furthermore, since the opposite side of the solar incidence always points to deep space, the dawn-dusk orbit has excellent heat dissipation performance by radiative cooling. Therefore, in the dawn-dusk orbit, there is an effect that a large amount of power can be secured and heat dissipation of high-heat-generating devices can be achieved. The information processing device 81 is an example of a high-heat-generating device.

[0135] Also, with the recent large-scale and high-speed development of cloud computing, the issues of increased power consumption and heat dissipation countermeasures for high-heat-generating devices also exist in the cloud environment of the ground system. Therefore, by regarding the artificial satellite 80 equipped with an edge server as an IoT and performing distributed computing, there is an effect that the load on the ground system can be reduced and contributions can be made to the SDGs. Furthermore, by equipping the artificial satellite 80 with a supercomputer or a cloud server and installing a centralized computing device in space, there is an effect that the load on the ground system can be reduced and contributions can be made to the SDGs. IoT is an abbreviation for Internet of Things. SDGs is an abbreviation for Sustainable Development Goals.

[0136] <Configuration example of communication satellite constellation 801> FIG. 26 is a diagram showing a configuration example of the communication satellite constellation 801 according to the present embodiment. The communication satellite constellation 801 is a satellite constellation flying in a sun-synchronous orbit at LST 06:00 or LST 18:00. The communication satellite constellation 801 includes communication satellites equipped with communication devices with the ground. The communication satellite is an example of the artificial satellite 80. In addition, the communication satellite constellation 801 forms an annular communication network by including communication devices for communication between communication satellites flying before and after in the same orbital plane.

[0137] According to the communication satellite constellation 801, in the communication satellite, since power can be constantly generated by a fixed solar cell, there is an effect that the communication satellite can be realized at low cost.

[0138] <Configuration example of satellite constellation 802> FIG. 27 is a diagram showing a configuration example of the satellite constellation 802 according to the present embodiment. In FIG. 27, in the satellite constellation 802, the satellite is equipped with an edge server. The satellite constellation 802 flies in a sun-synchronous orbit at LST 06:00 or LST 18:00. The satellite constellation 802 includes satellites. The satellite is an example of the artificial satellite 80.

[0139] The satellite is equipped with a computer or supercomputer equipped with satellite AI and at least one of a cloud server or an edge server as an information processing device 81. Also, in the satellite, a solar cell is directed to the sunlight incident side, and a heat dissipation surface of the information processing device 81 is provided on the side opposite to the sunlight incidence. In the satellite, a solar cell is directed to the sunlight incident side, and on the side opposite to the sunlight incidence, for example, a heat dissipation surface of a computer or an edge server is provided. The satellite is equipped with a communication device with the ground.

[0140] The satellite constellation 802 is equipped with a communication device for communication between satellites flying before and after in the same orbital plane to form an annular communication network. That is, the satellites constituting the satellite constellation 802 are equipped with a communication device for communication between satellites flying before and after in the same orbital plane to form an annular communication network.

[0141] The sun-synchronous orbit passes through the polar regions once a week. Therefore, according to the satellite constellation 802, there is an effect that all satellites can always communicate with a ground data center installed in the high-latitude band via the annular communication network.

[0142] FIG. 28 is a diagram showing another example of the configuration of the satellite constellation 802 according to the present embodiment. In FIG. 28, the satellite constellation 802 is composed of a communication satellite, a satellite equipped with a supercomputer, and a satellite equipped with a cloud server. According to the satellite constellation 802 in FIG. 28, since the results of analysis processing on the orbit can be delivered to ground users, there is an effect that the burden on the ground system can be reduced.

[0143] <Configuration example of Example 1 of the satellite information transmission system 503> FIG. 29 is a diagram showing a configuration example of Example 1 of the satellite information transmission system 503 according to the present embodiment. In FIG. 29, the state of the satellite information transmission system 503 as viewed from the sun direction is shown.

[0144] Example 1 of the satellite information transmission system 503 is composed of a user satellite group, a communication satellite group, and ground facilities. The user satellite group consists of user satellites flying in a low Earth orbit (LEO) with an orbital altitude of 500 km or more and 2000 km or less. The communication satellite group consists of a plurality of communication satellites flying in a sun-synchronous orbit at LST 06:00 or LST 18:00. Each satellite of the communication satellite group is an example of the artificial satellite 80.

[0145] The communication satellite group includes a first satellite that communicates with ground facilities and a second satellite that communicates with user satellites. The communication satellite group communicates with communication satellites flying in front and behind. The user satellite and the ground facility exchange information via the communication satellite group.

[0146] For satellites in a sun-synchronous orbit, due to the effect of the Earth's rotation, communication with ground facilities is possible only in the same time zone of LST from the low-latitude zone to the mid-latitude zone. On the other hand, as long as a view can be secured over the polar region, communication with ground facilities is possible at all times without being limited to the time zone of LST. Therefore, by communicating with the front and rear satellites to form an annular communication network and having a satellite passing near the polar region communicate with the ground facility on behalf of others, communication with the ground facility can be achieved at all times.

[0147] The user satellite constitutes a flying object tracking system that is responsible for detecting and tracking the launch of flying objects. The information of the user satellite needs to transfer satellite information quickly in case of an emergency. According to Example 1 of the satellite information transmission system 503, there is an effect that satellite information can be quickly transmitted to ground facilities installed in the high-latitude zone via the annular communication network. Note that the user satellites constituting the flying object tracking system include surveillance satellites equipped with infrared detection devices and a communication satellite group formed in an inclined orbit.

[0148] <Configuration example of Example 2 of the satellite information transmission system 503> FIG. 30 is a diagram showing a configuration example of Example 2 of the satellite information transmission system 503 according to the present embodiment. In FIG. 30, a state of viewing the satellite information transmission system 503 from the North Pole is shown.

[0149] Example 2 of the satellite information transmission system 503 is composed of a first communication constellation 831, a second communication constellation 832, and ground facilities.

[0150] The first communication constellation 831 flies in an equatorial orbit. Also, the first communication constellation 831 is formed by a plurality of satellites equipped with a first communication device that communicates with satellites before and after in the traveling direction on the same orbital plane to form an annular communication network. The second communication constellation 832 flies in a sun-synchronous orbit. Also, the second communication constellation 832 is formed by a plurality of satellites equipped with a first communication device that communicates with satellites before and after in the traveling direction on the same orbital plane to form an annular communication network.

[0151] Each satellite of the first communication constellation 831 and the second communication constellation 832 is equipped with a second communication device through which the first communication constellation 831 and the second communication constellation 832 communicate. Each satellite of the first communication constellation 831 and the second communication constellation 832 transmits satellite information to ground facilities via the first communication constellation 831 and the second communication constellation 832.

[0152] Alternatively, each satellite of the first communication constellation and the second communication constellation may be equipped with a communication device that communicates with user satellites. The user satellite may transmit satellite information to ground facilities via the first communication constellation 831 and the second communication constellation 832.

[0153] There may be a case where satellite information obtained by a satellite flying in an equatorial orbit is transmitted to ground facilities installed from the mid-latitude zone to the high-latitude zone. In such a case, it is reasonable for an equatorial satellite that forms an annular communication network in the longitudinal direction and a sun-synchronous satellite that forms an annular communication network in the latitudinal direction to communicate with each other. If there are ground facilities in the high-latitude zone where the sun-synchronous satellite can ensure a communication field of view when passing over the polar region, there is an effect that satellite information obtained by the equatorial satellite can be transmitted to the ground facilities almost in real time with only one orbital plane of the sun-synchronous satellite. Needless to say, the first communication constellation and the second communication constellation may each be equipped with a communication device for communicating with a user satellite.

[0154] <Configuration example of Example 3 of satellite information transmission system 503> FIG. 31 is a diagram showing a configuration example of Example 3 of the satellite information transmission system 503 according to the present embodiment. In FIG. 31, a state of viewing the satellite information transmission system 503 from the North Pole is shown.

[0155] Example 3 of the satellite information transmission system 503 includes a first communication constellation 831, a second communication constellation 832, a third communication constellation 833, and ground facilities.

[0156] The first communication constellation 831 flies in an equatorial orbit. Also, the first communication constellation 831 is formed by a plurality of satellites equipped with a first communication device that communicates with satellites before and after in the traveling direction on the same orbital plane to form an annular communication network. The second communication constellation 832 flies in a sun-synchronous orbit. Also, the second communication constellation 832 is formed by a plurality of satellites equipped with a first communication device that communicates with satellites before and after in the traveling direction on the same orbital plane to form an annular communication network. The third communication constellation 833 flies in an inclined orbit. Also, the third communication constellation 833 is formed by a plurality of satellites equipped with a first communication device that communicates with satellites before and after in the traveling direction on the same orbital plane to form an annular communication network.

[0157] Each satellite of the first communication constellation 831, the second communication constellation 832, and the third communication constellation 833 is equipped with a second communication device. The second communication device is a communication device for the first communication constellation and the second communication constellation, or the second communication constellation and the third communication constellation, or the third communication constellation and the first communication constellation to communicate with each other.

[0158] Each satellite of the first communication constellation 831, the second communication constellation 832, and the third communication constellation 833 transmits satellite information to ground facilities via at least two of the first communication constellation 831, the second communication constellation 832, and the third communication constellation 833.

[0159] Alternatively, each satellite of the first communication constellation, the second communication constellation, and the third communication constellation 833 may be equipped with a communication device for communicating with user satellites. The user satellite may transmit satellite information to ground facilities via at least two of the first communication constellation 831, the second communication constellation 832, and the third communication constellation 833.

[0160] There may be a case where satellite information acquired by an equatorial orbit satellite is transmitted to ground facilities installed in the mid-latitude zone. In such a case, it is reasonable for an inclined orbit satellite that forms an annular communication network in an inclined orbit flying in the longitudinal direction in the mid-latitude zone, an equatorial satellite that forms an annular communication network in the longitudinal direction, and a sun-synchronous satellite that forms an annular communication network in the latitudinal direction to communicate with each other.

[0161] For example, when the ground facility is installed at 35 degrees north latitude, an inclined orbit satellite with an orbital inclination angle of 35 degrees flies in the longitudinal direction over the ground facility, so that the communication time with the ground facility can be ensured to be long. If an inclined orbit satellite group having a plurality of orbital planes with normal vectors dispersed in the longitudinal direction is provided as the inclined orbit satellite group, there is an effect that satellite information acquired by an equatorial satellite can be transmitted to ground facilities almost in real time.

[0162] <Configuration Example of Example 4 of Satellite Information Transmission System 503> FIG. 32 is a diagram showing a configuration example of Example 4 of the satellite information transmission system 503 according to the present embodiment. In FIG. 32, a state of viewing the satellite information transmission system 503 from the North Pole is shown.

[0163] The fourth example of the satellite information transmission system 503 is composed of a first communication constellation 831a, a second communication constellation 832, and ground equipment.

[0164] The first communication constellation 831a flies in a sun-synchronous orbit. In addition, the first communication constellation 831a has a plurality of satellites each equipped with a first communication device that communicates with satellites in front and behind it in the direction of travel in the same orbital plane, forming a circular communication network. The second communication constellation 832 flies in a sun-synchronous orbit of an LST different from that of the first communication constellation 831a. In addition, the second communication constellation 832 has a circular communication network formed by a plurality of satellites each equipped with a first communication device that communicates with satellites in front and behind the satellite in the direction of travel on the same orbital plane.

[0165] Each satellite of the first communication constellation 831a and the second communication constellation 832 includes a second communication device with which the first communication constellation 831a and the second communication constellation 832 communicate when passing near the polar regions. Each satellite in the first communication constellation 831a and the second communication constellation 832 transmits satellite information to ground facilities via the first communication constellation 831a and the second communication constellation 832.

[0166] Sun-synchronous satellites are polar orbit satellites that pass over the vicinity of the polar regions. Therefore, the first communication constellation 831a and the second communication constellation 832 that form the circular communication network include satellites that can communicate over the vicinity of the polar regions. By transmitting satellite information to the circular communication network of the communication constellations of different LSTs, it is possible to transmit satellite information at a desired time period regardless of the latitude in which the ground equipment is installed.

[0167] <Configuration example 5 of the satellite information transmission system 503> FIG. 33 is a diagram showing a configuration example of Example 5 of a satellite information transmission system 503 according to the present embodiment. FIG. 33 shows the state of the satellite information transmission system 503 as seen from above the equator.

[0168] Example 5 of the satellite information transmission system 503 is composed of a first communication constellation 831, a second communication constellation 832a, and ground facilities.

[0169] The first communication constellation 831 flies in an equatorial orbit. Also, the first communication constellation 831 is formed by a plurality of satellites equipped with a first communication device that communicates with satellites before and after in the traveling direction on the same orbital plane to form an annular communication network. The second communication constellation 832a flies in an inclined orbit. Also, the second communication constellation 832a is formed by a plurality of satellites equipped with a first communication device that communicates with satellites before and after in the traveling direction on the same orbital plane to form an annular communication network.

[0170] Each satellite of the first communication constellation 831 and the second communication constellation 832a is equipped with a second communication device through which the first communication constellation 831 and the second communication constellation 832a communicate. Each satellite of the first communication constellation 831 and the second communication constellation 832a transmits satellite information to the ground facilities via the first communication constellation 831 and the second communication constellation 832a.

[0171] According to Example 5 of the satellite information transmission system 503, there is an effect that satellite information acquired by a satellite in an equatorial orbit can be transmitted to ground facilities installed in the mid-latitude zone. Also, the time period during which the second communication constellation 832a flies over the ground facilities is known in advance from the planned orbit information. Therefore, there is an effect that satellite information can be transmitted to the ground facilities at a desired time period when the second communication constellation 832a is composed of a plurality of orbital planes with different normal vectors.

[0172] Note that, as described in Embodiment 1, the satellite is controlled by commands transmitted from ground facilities. The ground facilities include a satellite constellation forming unit in a processor that forms a satellite constellation by communicating with each satellite. Also, a satellite constellation forming unit is provided on the satellite side, and the satellite constellation forming units of each of the plurality of satellites cooperate with the satellite constellation forming unit provided in the ground facilities to realize the control of the satellite constellation. Note that the satellite constellation forming unit of the satellite is provided in, for example, a satellite control device.

[0173] In the above Embodiments 1 to 6, each part of each system and each device such as a satellite monitoring system, a satellite information transmission system, ground facilities, a communication satellite, a monitoring system, a constituent satellite, a communication satellite constellation, a satellite constellation, an artificial satellite, and a satellite has been described as an independent functional block. However, the configuration of each system and each device does not have to be the configuration as in the above-described embodiments. As long as the functional blocks of each system and each device can realize the functions described in the above-described embodiments, any configuration may be used. Also, each system and each device may be a single device or a system composed of a plurality of devices. Also, among Embodiments 1 to 6, a plurality of parts or examples may be combined and implemented. Alternatively, one part or example among these embodiments may be implemented. In addition, these embodiments may be combined and implemented in any way, either as a whole or partially. That is, in Embodiments 1 to 6, free combinations of each embodiment, modifications of any constituent elements of each embodiment, or omissions of any constituent elements in each embodiment are possible.

[0174] Note that the above-described embodiments are essentially preferred examples and are not intended to limit the scope of the present disclosure, the scope of the application of the present disclosure, and the scope of the use of the present disclosure. The above-described embodiments can be variously modified as necessary.

Explanation of Symbols

[0175] 30 Satellite, 310,112,202 Satellite Control Device, 33,122,114,204 Propulsion Device, 34,115,205 Attitude Control Device, 35,123,116,206 Power Supply Device, 111,201 Observation Device, 32,121,113,203 Communication Device, 124,117 Camera, 41 First Communication Device, 42 Second Communication Device, 43 Third Communication Device, 44 Communication Satellite Group, 401 Communication Satellite, 402 Data Relay Satellite, 403 Meteorological Satellite, 404 Observation Satellite, 405 First Observation and Monitoring Satellite, 406 Positioning Satellite, 407 Second Observation and Monitoring Satellite, 408 Space Base, 409 Lunar and Planetary Exploration Satellite, 410 Exploration Satellite, 411 Transporter, 421 Optical Surveillance Satellite, 422 Infrared Surveillance Satellite, 423 Radio Surveillance Satellite, 424 Service Satellite, 425 Debris Removal Satellite, 51 Critical Infrastructure, 510 Infrastructure Satellite Group, 511 Infrastructure Satellite, 52 Surveillance Satellite Group, 521,521a,521b,521c Surveillance Satellite, 53 Surveillance Center, 54 Ground Facility for Each Infrastructure, 530 User Satellite Group, 531 User Satellite, 542 Radio Communication Terminal, 544 Optical Communication Terminal, 590 Surveillance Information, 61 First Satellite, 62 Second Satellite, 63 Third Satellite, 644 Fourth Satellite, 64 Transmission / Reception Switching Device, 65 Bidirectional Communication Terminal, 601 First Satellite Group, 602 Second Satellite Group, 603 Third Satellite Group, 500 Satellite Surveillance System, 501,503 Satellite Information Transmission System, 502 Monitoring System, 701,702 Ground Facility, 710 Surveillance Management Department, 720 Storage Unit, 80 Artificial Satellite, 81 Information Processing Device, 801 Communication Satellite Constellation, 802 Satellite Constellation, 810 First Satellite Constellation, 811,812 Constituent Satellite, 820 Second Satellite Constellation, 831,831a First Communication Constellation, 832,832a Second Communication Constellation, 833 Third Communication Constellation, 910 Processor, 921 Memory, 922 Auxiliary Storage Device, 930 Input Interface, 940 Output Interface, 941 Display Device, 950 Communication Device.

Claims

1. A critical infrastructure which is a social infrastructure in space, comprising a critical infrastructure satellite group composed of infrastructure satellites flying in a low Earth orbit (LEO) with an orbital altitude of 500 km or more and 2000 km or less, A monitoring satellite group composed of monitoring satellites flying in an orbit with an orbital altitude of 2000 km or less to monitor the infrastructure satellite group and perform on-orbit services, Ground facilities installed on the ground to exchange information with each infrastructure satellite of the infrastructure satellite group, A monitoring center installed on the ground to exchange information with the monitoring satellites, and comprising, The infrastructure satellite group includes a communication satellite group composed of communication satellites, The communication satellite group, flies in orbits with an orbital altitude and orbital inclination angle that result in a sun-synchronous orbit that makes an integer number of revolutions per day, evenly distributed, The communication satellites, communicate with communication satellites flying before and after, The communication satellite group, includes a first satellite that communicates with the ground facilities, a second satellite that communicates with the monitoring satellites, and a third satellite that only performs communication with communication satellites flying before and after, and comprising, Each of the communication satellites and the monitoring satellites, is equipped with a transmission / reception switching device that realizes reception and transmission by switching between a reception function and a transmission function, Ground facilities used in a satellite monitoring system in which the monitoring satellites and the monitoring center exchange information via the communication satellite group, It is installed at a latitude of 60° or more, communicates with the communication satellite once a week, and based on the data volume α of the command transmitted to the monitoring satellite and the data volume β of the monitoring data and telemetry received from the monitoring satellite, operates the transmission / reception switching device so that the ratio of the reception operation time during which the receiver function in the monitoring satellite operates to the transmission operation time during which the transmitter function operates is α to β, and implements information exchange with the monitoring satellite via the communication satellite.

2. A critical infrastructure that is a social infrastructure in space, and is composed of a group of infrastructure satellites flying in a low Earth orbit (LEO: Low Earth Orbit) with an orbital altitude of 500 km or more and 2000 km or less. Ground facilities installed on the ground that implement information exchange with each infrastructure satellite of the group of infrastructure satellites. Comprising: The group of infrastructure satellites: A group of communication satellites composed of communication satellites; And a group of user satellites composed of user satellites that use the group of communication satellites as a communication line. The group of communication satellites: Fly in an evenly arranged orbit with an orbital altitude and orbital inclination angle that result in a sun-synchronous orbit that makes an integer number of orbits per day. The communication satellites: Communicate with communication satellites flying in front and behind. The group of communication satellites: A first satellite that communicates with the ground facilities; A second satellite that communicates with the user satellites; And a third satellite that only communicates with communication satellites flying in front and behind. Comprising: Each of the communication satellites and the user satellites: Is equipped with a transmission / reception switching device that realizes reception and transmission by switching between a receiver function and a transmitter function. A ground facility used in a satellite information transmission system in which the user satellite and the ground facility exchange information via the communication satellite group, Installed at a latitude of 60° or more, communicating with the communication satellite once a week, based on the data volume α of the command transmitted to the user satellite and the data volume β of the monitoring data and telemetry received from the user satellite, the ground facility operates the transmission / reception switching device so that the ratio of the reception operation time when the receiver function in the user satellite operates to the transmission operation time when the transmitter function operates is α to β, and exchanges information with the user satellite via the communication satellite.

Images