Patent Publication Number: US-2023137948-A1

Title: Space traffic management system, space traffic management device, collision avoidance assist business device, ssa business device, mega-constellation business device, space traffic management method, and oadr

Description:
TECHNICAL FIELD 
     The present disclosure relates to a space traffic management system, a space traffic management device, a collision avoidance assist business device, an SSA business device, a mega-constellation business device, a space traffic management method, and an OADR. 
     BACKGROUND ART 
     In recent years, construction of a large-scale satellite constellation consisting of several hundred to several thousand satellites, or a so-called mega-constellation, has started, and a risk of satellite collision on an orbit is increasing. In addition, space debris such as satellites that have become uncontrollable due to failure, and rocket wreckage are increasing. 
     With this rapid increase of space objects such as satellites and space debris in outer space, there is an increasing need in space traffic management (STM) to create international rules for avoiding collisions of space objects. 
     Patent Literature 1 discloses a technique of forming a satellite constellation consisting of a plurality of satellites on the same circular orbit. 
     Conventionally, a framework exists with which the U.S. Combined Space Operations Center (CSpOC) continuously monitors space objects and issues an alarm when approach of space objects to each other or collision of space objects against each other is anticipated. In response to this alarm, manned space stations and commercial communication satellites carry out avoidance operation when it is determined to be necessary. However, in recent years, projects have been announced in the United States to transfer the framework of issuing alarms to private satellites, to a private business operator, and a new framework has been in need. 
     CITATION LIST 
     Patent Literature 
     Patent Literature 1: JP 2017-114159 A 
     SUMMARY OF INVENTION 
     Technical Problem 
     A framework is not available that allows mega-constellation business operators to avoid collisions with each other so that flight safety is ensured at an unsteady operation stage such as orbit insertion and orbital disposal. Thus, collision avoidance operations might be insufficient in the future. 
     Patent Literature 1 does not describe a framework that allows mega-constellation business operators to avoid collisions with each other so that flight safety is ensured. 
     The present disclosure has as its objective to provide a framework that allows a plurality of mega-constellation business devices to avoid collisions with each other so that flight safety is ensured at an unsteady operation stage such as orbit insertion and orbital disposal. 
     Solution to Problem 
     In a space traffic management system according to the present disclosure, space traffic management devices, individually mounted in a collision avoidance assist business device and a plurality of mega-constellation business devices and each including a database and a server, are connected to each other via a communication line, the collision avoidance assist business device assisting avoidance of collision of space objects with each other in outer space, the plurality of mega-constellation business devices managing mega-constellations which are satellite constellations each consisting of 100 or more satellites, 
     wherein the database provided to the space traffic management device of the collision avoidance assist business device records 
     orbital information, acquired from the plurality of mega-constellation business devices, of mega-constellation satellite groups during steady operation, and orbital information of an unsteady-operation space object, 
     wherein the server provided to the space traffic management device of the collision avoidance assist business device comprises 
     an orbital analysis unit to identify a mega-constellation satellite group formed in an orbital altitude which the mega-constellation satellite group is anticipated to pass during a flight of the unsteady-operation space object, and 
     an announcement unit to announce a danger alarm and orbital information of the unsteady-operation space object to the mega-constellation business devices which manage the mega-constellation satellite groups, and 
     wherein the server provided to the space traffic management device of each of the collision avoidance assist business devices comprises 
     a collision analysis unit to analyze collision of the unsteady-operation space object with an individual satellite constituting a mega-constellation satellite group, and 
     a countermeasure formulating unit to formulate a collision avoidance countermeasure when collision is predicted. 
     Advantageous Effects of Invention 
     A space traffic management system according to the present disclosure can provide a framework that allows a plurality of mega-constellation business devices to avoid collisions with each other so that flight safety is ensured at an unsteady operation stage such as orbit insertion and orbital disposal. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG.  1    presents an example in which a plurality of satellites cooperate with each other to realize a global communication service around the entire Earth. 
         FIG.  2    presents an example in which a plurality of satellites having the same single orbital plane realize an Earth observation service. 
         FIG.  3    presents an example of a satellite constellation having a plurality of orbital planes intersecting in vicinities of polar regions. 
         FIG.  4    presents an example of a satellite constellation having a plurality of orbital planes intersecting outside of the polar regions. 
         FIG.  5    is a configuration diagram of a satellite constellation forming system. 
         FIG.  6    is a configuration diagram of a satellite of the satellite constellation forming system. 
         FIG.  7    is a configuration diagram of a ground facility of the satellite constellation forming system. 
         FIG.  8    presents a function configuration example of the satellite constellation forming system. 
         FIG.  9    presents a hardware configuration example of a space traffic management device of a collision avoidance assist business device according to Embodiment 1. 
         FIG.  10    presents a hardware configuration example of a space traffic management device of a mega-constellation business device according to Embodiment 1. 
         FIG.  11    presents an example of orbital prediction information provided to a space information recorder according to Embodiment 1. 
         FIG.  12    presents a business example of mega-constellations currently under planning. 
         FIG.  13    is a diagram illustrating intrusion of a new launch rocket into mega-constellation satellite groups according to Embodiment 1. 
         FIG.  14    is a diagram illustrating intrusion of a satellite at an orbit insertion stage into mega-constellation satellite groups according to Embodiment 1. 
         FIG.  15    is a diagram illustrating intrusion of a satellite at an orbital descent stage into mega-constellation satellite groups according to Embodiment 1. 
         FIG.  16    presents an example of a change in a number of on-orbit objects of a mega-constellation satellite group according to Embodiment 1. 
         FIG.  17    presents an example of launching a rocket to a region of a mega-constellation satellite group according to Embodiment 1. 
         FIG.  18    presents an example of a flight image of a mega-constellation satellite group near an altitude of 340 km according to Embodiment 1. 
         FIG.  19    presents an overall configuration of an example of a space traffic management system according to Embodiment 1. 
         FIG.  20    presents a detailed configuration example of a space information recorder of the collision avoidance assist business device according to Embodiment 1. 
         FIG.  21    presents a detailed configuration example of a space information recorder of the mega-constellation business device according to Embodiment 1. 
         FIG.  22    is a flowchart illustrating a space traffic management process of the space traffic management system according to Embodiment 1. 
         FIG.  23    presents a hardware configuration example of a space traffic management device according to a modification of Embodiment 1. 
         FIG.  24    presents a function configuration example of an OADR according to Embodiment 2. 
         FIG.  25    presents a function configuration example of the OADR according to Embodiment 2. 
         FIG.  26    presents a function configuration example of the OADR according to Embodiment 2. 
     
    
    
     DESCRIPTION OF EMBODIMENTS 
     Embodiments of the present disclosure will now be described below with referring to drawings. In the drawings, the same or equivalent portion is denoted by the same reference sign. In description of the embodiments, where appropriate, the same or equivalent portion will not be described, or will be described only briefly. Further, in the drawings below, a relationship in size among configurations may differ from what it actually is. Further, in description of the embodiments, sometimes a direction or position such as “upper”, “lower”, “left”, “right”, “forward”, “backward”, “front”, and “rear” is indicated. These notations are merely given for descriptive convenience and do not limit a layout and orientation of a configuration such as a device, an appliance, and a component. 
     Embodiment 1 
     An example of a satellite constellation which is a prerequisite for a space traffic management system according to the embodiment below will be described. 
       FIG.  1    is a diagram illustrating an example in which a plurality of satellites cooperate with each other to realize a global communication service around an entire Earth  70 . 
       FIG.  1    illustrates a satellite constellation  20  that realizes the communication service around the entire Earth. 
     Regarding a plurality of satellites flying on the same orbital plane and at the same altitude, a ground communication service range of each satellite overlaps with a communication service range of a following satellite. Hence, with the plurality of such satellites, the plurality of satellites on the same orbital plane can provide a communication service for a particular point on the ground alternately in a time-division manner. If an adjacent orbital plane is formed, the communication service can exhaustively cover the surface of the ground between adjacent orbits. Likewise, if a large number of orbital planes are arranged almost evenly around the Earth, it is possible to provide a global communication service for the ground around the entire Earth. 
       FIG.  2    is a diagram illustrating an example in which a plurality of satellites having the same single orbital plane realize an Earth observation service. 
       FIG.  2    illustrates a satellite constellation  20  that realizes the Earth observation service. In the satellite constellation  20  of  FIG.  2   , satellites each equipped with an Earth observation device, which is an optical sensor or a radio wave sensor such as a synthetic aperture radar, fly on the same orbital plane and at the same altitude. In this manner, with a satellite group  300  in which a ground imaging range of a following satellite overlaps a preceding ground imaging range with a time delay, the plurality of satellites on the orbit sense a ground image of a particular point on the ground alternately in a time-division manner, thereby providing the Earth observation service. 
     In this manner, the satellite constellation  20  is constituted of the satellite groups  300  each formed of the plurality of satellites having individual orbital planes. In the satellite constellation  20 , the service is provided by cooperation of the satellite group  300 . The satellite constellation  20  specifically refers to a satellite constellation formed of one satellite group run by a communication business service company as illustrated in  FIG.  1   , or by an observation business service company as illustrated in  FIG.  2   . 
       FIG.  3    presents an example of a satellite constellation  20  having a plurality of orbital planes  21  intersecting in vicinities of polar regions.  FIG.  4    presents an example of a satellite constellation  20  having a plurality of orbital planes  21  intersecting outside of the polar regions. 
     In the satellite constellation  20  of  FIG.  3   , orbital inclinations of the individual orbital planes  21  of the plurality of orbital planes are approximately 90 degrees, and the individual orbital planes  21  of the plurality of orbital planes exist on different planes. 
     In the satellite constellation  20  of  FIG.  4   , orbital inclinations of orbital planes  21  of the plurality of orbital planes are not approximately 90 degrees, and the individual orbital planes  21  of the plurality of orbital planes exist on different planes. 
     In the satellite constellation  20  of  FIG.  3   , two arbitrary orbital planes intersect at points in the vicinities of polar regions. In the satellite constellation  20  of  FIG.  4   , two arbitrary orbital planes intersect at points outside of the polar regions. In  FIG.  3   , there is a possibility that collision of satellites  30  occurs in the vicinities of the polar regions. As illustrated in  FIG.  4   , intersections of the plurality of orbital planes having orbital inclinations of more than 90 degrees move to separate from the polar regions according to the orbital inclinations. Also, depending on a combination of the orbital planes, there is a possibility that the orbital planes intersect at various positions including a vicinity of an equator. Accordingly, a location where collision of the satellites  30  can occur varies. The satellites  30  are also called artificial satellites. 
     Particularly, in recent years, construction of a large-scale satellite constellation consisting of several hundred to several thousand satellites has started, and a risk of satellite collision on the orbit is increasing. In addition, debris such as artificial satellites that have become uncontrollable due to failure, and rocket wreckage, are increasing. The large-scale satellite constellation is also called a mega-constellation. Such debris is also called space debris. 
     In this manner, as the debris increases in outer space and a number of satellites typically represented by mega-constellations increases rapidly, demands for space traffic management (STM) have arisen. 
     Also, to realize orbital transfer of a space object, demands have arisen for post-mission disposal (PMD) that takes place after a mission on the orbit is ended, or for ADR according to which debris such as a failed satellite and a floating upper block of a rocket is subjected to orbital disposal by an external means such as a debris removal satellite. International discussion for STM about such ADR demands has begun. PMD stands for Post Mission Disposal. ADR stands for Active Debris Removal. STM stands for Space Traffic Management. 
     With referring to  FIGS.  5  to  8   , description will be made on an example of a satellite  30  and a ground facility  700  in a satellite constellation forming system  600  which forms the satellite constellation  20 . For example, the satellite constellation forming system  600  is operated by a business operator that runs a satellite constellation business of a mega-constellation business device  41 , an LEO constellation business device, a satellite business device, or the like. LEO stands for Low Earth Orbit. 
     A satellite control scheme using the satellite constellation forming system  600  is also applied to a business device  40  that controls a satellite. For example, this satellite control scheme may be loaded in a business device  40  such as a debris removal business device  45  which manages a debris removal satellite, a rocket launch business device  46  which launches a rocket, and orbital transfer business devices  44  which manage orbital transfer satellites. 
     The satellite control scheme using the satellite constellation forming system  600  may be loaded in any business device as far as it is a business device of a business operator that manages a space object  60 . 
     Individual devices of the business devices  40  will be described later. 
       FIG.  5    is a configuration diagram of the satellite constellation forming system  600 . 
     The satellite constellation forming system  600  is provided with a computer.  FIG.  5    illustrates a one-computer configuration. In practice, computers are provided to the individual satellites  30  of the plurality of satellites constituting the satellite constellation  20  and to the ground facility  700  which communicates with the satellites  30 . The computers provided to the individual satellites  30  of the plurality of satellites and to the ground facility  700  communicating with the satellites  30  cooperate with each other to implement functions of the satellite constellation forming system  600 . In the following, an example of a configuration of a computer that implements the functions of the satellite constellation forming system  600  will be described. 
     The satellite constellation forming system  600  is provided with the satellites  30  and the ground facility  700 . Each satellite  30  is provided with a satellite communication device  32  to communicate with a communication device  950  of the ground facility  700 .  FIG.  5    illustrates the satellite communication device  32  among configurations provided to the satellite  30 . 
     The satellite constellation forming system  600  is provided with a processor  910  and other hardware devices as well, 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 devices via a signal line and controls the other hardware devices. The hardware of the satellite constellation forming system  600  is the same as hardware of a space traffic management device  100  to be described later with referring to  FIG.  9   . 
     The satellite constellation forming system  600  is provided with a satellite constellation forming unit  11  as a function element. A function of the satellite constellation forming unit  11  is implemented by hardware or software. 
     The satellite constellation forming unit  11  controls formation of the satellite constellation  20  while communicating with the satellites  30 . 
       FIG.  6    is a configuration diagram of the satellite  30  of the satellite constellation forming system  600 . 
     The satellite  30  is provided with a satellite control device  31 , a satellite communication device  32 , a propulsion device  33 , an attitude control device  34 , and a power supply device  35 . The satellite  30  is also provided with other constituent elements that implement various types of functions. With referring to  FIG.  6   , description will be made on the satellite control device  31 , the satellite communication device  32 , the propulsion device  33 , the attitude control device  34 , and the power supply device  35 . The satellite  30  is an example of the space object  60 . 
     The satellite control device  31  is a computer that controls the propulsion device  33  and the attitude control device  34 , and is provided with a processing circuit. Specifically, the satellite control device  31  controls the propulsion device  33  and the attitude control device  34  in accordance with various types of commands transmitted from the ground facility  700 . 
     The satellite communication device  32  is a device that communicates with the ground facility  700 . Specifically, the satellite communication device  32  transmits various types of data concerning its own satellite to the ground facility  700 . The satellite communication device  32  receives various types of commands transmitted from the ground facility  700 . 
     The propulsion device  33  is a device to give propulsion to the satellite  30  and changes a speed of the satellite  30 . Specifically, the propulsion device  33  is an apogee kick motor, a chemical propulsion device, or an electric propulsion device. The apogee kick motor (AKM) refers to an upper-block propulsion device used for orbit insertion of an artificial satellite, and is also called an apogee motor (when a solid rocket motor is employed) or an apogee engine (when a liquid engine is employed). 
     The chemical propulsion device is a thruster that uses a one-component or two-component fuel. An example of the electric propulsion device is an ion engine or a Hall thruster. Apogee kick motor is a name of a device used for orbital transfer, and is sometimes a kind of chemical propulsion device. 
     The attitude control device  34  is a device to control attitude elements such as an attitude of the satellite  30 , an angular velocity of the satellite  30 , and a Line of Sight. The attitude control device  34  changes the attitude elements into desired directions. Alternatively, the attitude control device  34  maintains the attitude elements in desired directions. The attitude control device  34  is provided with 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 rection wheel, and a control moment gyro. The controller controls the actuator in accordance with measurement data of the attitude sensor or various types of commands from the ground facility  700 . 
     The power supply device  35  is provided with apparatuses such as a solar cell, a battery, and a power control device, and supplies power to the apparatuses mounted in the satellite  30 . 
     The processing circuit provided to the satellite control device  31  will be described. 
     The processing circuit may be dedicated hardware, or may be a processor that runs a program stored in the memory. 
     In the processing circuit, some of its functions may be implemented by dedicated hardware, and its remaining functions may be implemented by software or firmware. That is, the processing circuit can be implemented by hardware, software, or firmware; or a combination of hardware, software, and firmware. 
     The dedicated hardware is specifically a single circuit, a composite circuit, a programmed processor, a parallel-programmed processor, an ASIC, or an FPGA; or a combination of a single circuit, a composite circuit, a programmed processor, a parallel-programmed processor, an ASIC, and an FPGA. 
     ASIC stands for Application Specific Integrated Circuit. FPGA stands for Field Programmable Gate Array. 
       FIG.  7    is a configuration diagram of the ground facility  700  provided to the satellite constellation forming system  600 . 
     The ground facility  700  program-controls a large number of satellites on every orbit plane. The ground facility  700  is an example of a ground device. The ground device is constituted of: a ground station including, for example, a ground antenna device, a communication device connected to the ground antenna device, and an electronic calculator; and a ground facility serving as a server or terminal connected to the ground station via a network. The ground device may include a communication device mounted in a mobile body such as an aircraft, an automotive vehicle, and a mobile terminal. 
     The ground facility  700  forms the satellite constellation  20  through communication with the satellites  30 . The ground facility  700  is provided to the space traffic management device  100 . The ground facility  700  is provided with the processor  910  and other hardware devices such as the memory  921 , the auxiliary storage device  922 , the input interface  930 , the output interface  940 , and the communication device  950 . The processor  910  is connected to the other hardware devices via the signal line and controls the other hardware devices. The hardware of the ground facility  700  is the same as hardware of the space traffic management device  100  to be described later with referring to  FIG.  9   . 
     The ground facility  700  is provided with an orbit control command generation unit  510  and an analytical prediction unit  520 , as function elements. Functions of the orbit control command generation unit  510  and analytical prediction unit  520  are implemented by hardware or software. 
     The communication device  950  transmits and receives a signal that performs tracking control of the satellites  30  of the satellite group  300  constituting the satellite constellation  20 . Also, the communication device  950  transmits an orbit control command  55  to the satellites  30 . 
     The analytical prediction unit  520  analytically predicts orbits of the satellites  30 . 
     The orbit control command generation unit  510  generates the orbit control command  55  to be transmitted to the satellites  30 . 
     The orbit control command generation unit  510  and the analytical prediction unit  520  implement the function of the satellite constellation forming unit  11 . That is, the orbit control command generation unit  510  and the analytical prediction unit  520  are examples of the satellite constellation forming unit  11 . 
       FIG.  8    is a diagram illustrating a function configuration example of the satellite constellation forming system  600 . 
     The satellite  30  is further provided with a satellite constellation forming unit  11   b  which forms the satellite constellation  20 . The satellite constellation forming units  11   b  of the individual satellites  30  of the plurality of satellites and the satellite constellation forming unit  11  provided to the ground facility  700  cooperate with each other to implement the functions of the satellite constellation forming system  600 . Alternatively, the satellite constellation forming unit  11   b  of the satellite  30  may be provided to the satellite control device  31 . 
     Description of Configurations 
     A space traffic management system  500  according to the present embodiment is provided with a collision avoidance assist business device  43  and a plurality of mega-constellation business devices  41 . The collision avoidance assist business device  43  assists avoidance of collision of space objects with each other in outer space. The mega-constellation business devices  41  manage mega-constellations which are satellite constellations each consisting of 100 or more satellites. 
     The space traffic management device  100  according to the present embodiment is mounted in the collision avoidance assist business device  43  and in each of the plurality of mega-constellation business devices  41 , and is provided with a database  211  and a server  212 . A space traffic management device  100  may be mounted in a space insurance business device  47  of a space insurance business operator which runs a space insurance business. 
     In the space traffic management system  500 , the space traffic management devices  100  individually mounted in the collision avoidance assist business device  43 , the plurality of mega-constellation business devices  41 , and the space insurance business device  47  are connected to each other via a communication line. 
       FIG.  9    is a diagram illustrating a hardware configuration example of the space traffic management device  100  of the collision avoidance assist business device  43  according to the present embodiment. 
       FIG.  10    is a diagram illustrating a hardware configuration example of the space traffic management device  100  of the mega-constellation business device  41  according to the present embodiment. 
     In the present embodiment, the space traffic management device  100  is mounted in each of the plurality of mega-constellation business devices  41 , the space insurance business device  47 , and the collision avoidance assist business device  43 . 
     The mega-constellation business device  41  manages the satellite constellation consisting of a plurality of satellites. Specifically, the mega-constellation business device  41  is a computer of a mega-constellation business operator which runs a large-scale satellite constellation business, that is, a mega-constellation business. The mega-constellation business device  41  is an example of a satellite constellation business device that manages a satellite constellation consisting of, for example, 100 or more satellites. 
     The collision avoidance assist business device  43  assists avoidance of collision of space objects with each other in outer space. Specifically, the collision avoidance assist business device  43  is a computer of a collision avoidance assist business operator which assists avoidance of collision of space objects with each other in outer space. 
     The business devices  40  may include business devices such as an LEO constellation business device, a satellite business device, an orbital transfer business device, a debris removal business device, a rocket launch business device, and a space situational awareness (SSA) business device, in addition to the mega-constellation business devices  41 , the space object business device  42 , and the collision avoidance assist business device  43 . 
     Each business device  40  provides information concerning the space object  60  such as an artificial satellite managed by each device, and debris. The business device  40  is a computer of a business operator which collects information concerning the space object  60  such as the artificial satellite and debris. 
     The LEO constellation business device is a computer of an LEO constellation business operator which runs a low-Earth-orbit constellation business, that is, an LEO constellation business. 
     The satellite business device is a computer of a satellite business operator which deals with one to several satellites. 
     The orbital transfer business device is a computer of an orbital transfer business operator which issues a space object intrusion alarm about a satellite. 
     The debris removal business device is a computer of a debris removal business operator which runs a debris removal business. 
     The rocket launch business device is a computer of the rocket launch business operator which runs the rocket launch business. 
     The SSA business device is a computer of an SSA business operator which runs an SSA business, that is a space situational awareness business. 
     A space traffic management device  100  may be mounted in a ground facility  701  provided to each business device  40 . A space traffic management device  100  may be mounted in the satellite constellation forming system  600 . 
     The space traffic management device  100  is provided with a processor  910 , and is provided with other hardware devices as well, 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 devices via a signal line and controls the other hardware devices. 
     The processor  910  is an example of a server. The memory  921  and the auxiliary storage device  922  are examples of the database  211 . The server  212  may be provided with other hardware devices such as an input interface  930 , an output interface  940 , a communication device  950 , and a storage apparatus. The server  212  implements individual functions of the mega-constellation business device  41 , the space insurance business device  47 , and the collision avoidance assist business device  43 . 
     As illustrated in  FIG.  9   , the space traffic management device  100  of the collision avoidance assist business device  43  is provided with an orbital analysis unit  431 , an announcement unit  432 , and a storage unit  140 , as examples of function elements that implement a collision avoidance assist function. A space information recorder  101  is stored in the storage unit  140 . 
     As illustrated in  FIG.  10   , the space traffic management device  100  of the mega-constellation business device  41  is provided with a collision analysis unit  411 , a countermeasure formulating unit  412 , and a storage unit  140 , as examples of function elements that implement a mega-constellation management function. A space information recorder  101  is stored in the storage unit  140 . 
     In the following, a hardware configuration of the space traffic management device  100  will be described with referring to  FIG.  9   , using the space traffic management device  100  of the collision avoidance assist business device  43  as an example. Note that the space traffic management device  100  of another business device  40  has the same hardware configuration. 
     To simplify the description, a configuration having the same function is denoted by the same reference sign. However, the mega-constellation business device  41 , the collision avoidance assist business device  43 , and the space insurance business device  47  individually have a hardware configuration and a function configuration, per device. 
     Functions of the orbital analysis unit  431  and announcement unit  432  are implemented by software. The storage unit  140  is provided to the memory  921 . Alternatively, the storage unit  140  may be provided to the auxiliary storage device  922 . Also, the storage unit  140  may be divided between the memory  921  and the auxiliary storage device  922 . 
       FIG.  9    describes the space traffic management device  100  as a device that implements a function of collision avoidance assistance. However, the space traffic management device  100  has various functions other than the function of collision avoidance assistance. 
     The processor  910  is a device that runs a space traffic management program. The space traffic management program is a program that implements the functions of various constituent elements of the space traffic management device  100  and space traffic management system  500 . 
     The processor  910  is an Integrated Circuit (IC) that performs computation processing. Specific examples of the processor  910  are a Central Processing Unit (CPU), a Digital Signal Processor (DSP), and a Graphics Processing Unit (GPU). 
     The memory  921  is a storage device that stores data temporarily. A specific example of the memory  921  is a Static Random-Access Memory (SRAM) or a Dynamic Random-Access Memory (DRAM). 
     The auxiliary storage device  922  is a storage device that keeps data. A specific example of the auxiliary storage device  922  is an HDD. Alternatively, 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) Disc, and a DVD. HDD stands for Hard Disk Drive. SD (registered trademark) stands for Secure Digital. CF stands for CompactFlash (registered trademark). DVD stands for Digital Versatile Disk. 
     The input interface  930  is a port to be connected to an input device such as a mouse, a keyboard, and a touch panel. The input interface  930  is specifically a Universal Serial Bus (USB) terminal. Alternatively, the input interface  930  may be a port to be connected to a Local Area Network (LAN). 
     The output interface  940  is a port to which a cable of a display apparatus  941  such as a display is to be connected. The output interface  940  is specifically a USB terminal or a High-Definition Multimedia Interface (HDMI, registered trademark) terminal. The display is specifically a Liquid Crystal Display (LCD). 
     The communication device  950  has a receiver and a transmitter. The communication device  950  is specifically a communication chip or a Network Interface Card (NIC). In the present embodiment, the space traffic management devices  100  of the mega-constellation business devices  41 , space insurance business device  47 , and collision avoidance assist business device  43  communicate with each other via the communication line. 
     The space traffic management program is read by the processor  910  and run by the processor  910 . Not only the space traffic management program but also an Operating System (OS) is stored in the memory  921 . The processor  910  runs the space traffic management program while running the OS. The space traffic management program and the OS may be stored in the auxiliary storage device  922 . The space traffic management program and the OS which are stored in the auxiliary storage device  922  are loaded into the memory  921  and run by the processor  910 . Part or a whole of the space traffic management program may be built in the OS. 
     The space traffic management device  100  may be provided with a plurality of processors that substitute for the processor  910 . The plurality of processors share running of the program. Each processor is a device that runs the program, just as the processor  910  does. 
     Data, information, signal values, and variable values which are used, processed, or outputted by the program are stored in the memory  921 , the auxiliary storage device  922 , or a register or cache memory in the processor  910 . 
     The term “unit” in each unit of the space traffic management device may be replaced by “process”, “procedure”, “means”, “phase”, or “stage”. The term “process” in an orbital analysis process and in an alarming process may be replaced by “program”, “program product”, or “program-recorded computer-readable recording medium” recorded with a program. The terms “process”, “procedure”, “means”, “phase”, and “stage” are replaceable with one another. 
     The space traffic management program causes the computer to execute processes, procedures, means, phases, or stages corresponding to the individual units in the space traffic management system, with the “units” being replaced by “processes”, “procedures”, “means”, “phases”, or “stages”. A space traffic management method is a method that is carried out by the space traffic management device  100  running the space traffic management program. 
     The space traffic management program may be provided as being stored in a computer-readable recording medium. Each program may be provided in the form of a program product. 
       FIG.  11    is a diagram illustrating an example of orbit prediction information  51  provided to the space information recorder  101  according to the present embodiment. 
     The space traffic management device  100  stores, to the storage unit  140 , the orbit prediction information  51  in which prediction values of the orbit of the space object  60  are set. For example, the space traffic management device  100  may acquire prediction values of orbits of a plurality of space objects  60  from the business device  40  utilized by a management business operator which manages the plurality of space objects  60 , and may store the prediction values as orbit prediction information  51 . Alternatively, the space traffic management device  100  may acquire, from the management business operator, orbit prediction information  51  in which prediction values of orbits of a plurality of space objects  60  are set, and may store the acquired orbit prediction information  51  to the storage unit  140 . 
     The management business operator is a business operator that manages the space object  60  such as a satellite constellation, various types of satellites, a rocket, and debris, which fly in space. As described above, the management business device  40  utilized by each management business operator is a computer such as the mega-constellation business device, the LEO constellation business device, the satellite business device, the orbital transfer business device, the debris removal business device, the rocket launch business device, and the SSA business device. 
     The orbit prediction information  51  includes satellite orbit prediction information  52  and debris orbit prediction information  53 . Prediction values of an orbit of a satellite are set in the satellite orbit prediction information  52 . Prediction values of an orbit of debris are set in the debris orbit prediction information  53 . In the present embodiment, the satellite orbit prediction information  52  and the debris orbit prediction information  53  are included in the orbit prediction information  51 . However, the satellite orbit prediction information  52  and the debris orbit prediction information  53  may be stored in the storage unit  140  as different pieces of information. 
     Information such as, for example, a space object Identifier (ID)  511 , a predicted epoch  512 , predicted orbital elements  513 , and predicted errors  514  are set in the orbit prediction information  51 . 
     The space object ID  511  is an identifier that identifies a space object  60 . In  FIG.  11   , a satellite ID and a debris ID are set as the space object ID  511 . The space object is specifically an object such as a rocket to be launched to outer space, an artificial satellite, a space base, a debris removal satellite, a planetary space probe, and a satellite or rocket that turned into debris after a mission is completed. 
     The predicted epoch  512  is an epoch predicted for an orbit of each of the plurality of space objects. 
     The predicted orbital elements  513  are orbital elements that identify an orbit of each of the plurality of space objects. The predicted orbital elements  513  are orbital elements predicted for the orbit of each of the plurality of space objects. In  FIG.  11   , Keplerian six orbital elements are set as the predicted orbital elements  513 . 
     The predicted errors  514  are errors predicted for an orbit of each of the plurality of space objects. A traveling-direction error, an orthogonal-direction error, and an error basis are set in the predicted errors  514 . In this manner, error amounts involved in performance values are explicitly indicated in the predicted errors  514 , together with their bases. The bases of the error amounts include contents of data processing carried out as a measurement means and as an accuracy improving means of position coordinate information, and part or a whole of statistic evaluation results of past data. 
     In the orbit prediction information  51  according to the present embodiment, the predicted epoch  512  and the predicted orbital elements  513  are set concerning the space object  60 . A time and position coordinates of the space object  60  in the near future can be obtained from the predicted epoch  512  and the predicted orbital elements  513 . For example, the time and position coordinates of the space object  60  in the near future may be set in the orbit prediction information  51 . 
     In this manner, the orbit prediction information  51  is provided with orbital information of the space object, including the epoch and the orbital elements or the time and the position coordinates, to explicitly indicate predicted values of the space object  60  in the near future. 
     Description of Functions 
     &lt;Necessity for Space Traffic Management System  500  according to Present Embodiment&gt; 
     A necessity for the space traffic management system  500  according to the present embodiment will be described with referring to  FIGS.  12  through  18   . 
       FIG.  12    is a diagram of a business example of a mega-constellation which is currently under planning. 
       FIG.  13    is a diagram illustrating intrusion of a new launch rocket into mega-constellation satellite groups according to the present embodiment. 
       FIG.  14    is a diagram illustrating intrusion of a satellite at an orbit insertion stage into mega-constellation satellite groups according to the present embodiment. 
       FIG.  15    is a diagram illustrating intrusion of a satellite at an orbital descent stage into mega-constellation satellite groups according to the present embodiment. 
     As illustrated in  FIG.  12   , a plurality of mega-constellation business operators advocate a project of deploying many, several hundred to several ten-thousand satellites as if to exhaustively cover the sky. 
     At the present stage, a mega-constellation business operator A has already announced a deployment project involving about 42,000 satellites, a mega-constellation business operator B has announced a deployment project involving about 3,000 satellites, and a mega-constellation business operator C has announced a deployment project involving about 600 satellites. 
     As illustrated in  FIG.  13   , at the stage of deploying mega-constellation satellite groups, as a total number of satellites deployed on orbits increases, a collision risk during new rocket launch increases. 
     As illustrated in  FIG.  14   , some satellite business operators announce a project in which after a rocket is launched and a satellite is disconnected, a propulsion device provided to the satellite raises an altitude of the satellite, thereby performing orbit insertion. This is aimed at reducing a risk that a rocket upper block remains as debris. In this case as well, however, as the total number of satellites deployed on the orbit increases, a collision risk during an orbit insertion process increases. 
     As illustrated in  FIG.  15   , a collision risk exists even after each mega-constellation business operator has completed deployment of all satellites and steady operation is started. Specifically, after completion of the satellite life, in a process of orbital disposal by PMD and lowering a trajectory altitude until atmospheric entry, a risk exists that a satellite at an orbital descent stage collides with a mega-constellation satellite group that is in steady operation. 
     In this manner, a space object such as an unsteadily-operation satellite and a rocket poses a collision risk against a mega-constellation satellite group which is deployed as if to exhaustively cover the sky and performs steady operation. 
       FIG.  16    is a diagram illustrating an example of a change in a number of on-orbit objects in a mega-constellation satellite group according to the present embodiment. 
     As illustrated in  FIG.  16   , at a terminal period of a design life, a satellite to follow a satellite that has been performing steady operation so far must be put into orbit in order to continue the service. Accordingly, the number of on-orbit objects multiplies in a generation shift process. Also, if a deorbit period taken until atmospheric entry after PMD is longer than a satellite life, the total number of on-orbit objects further increases during generation shift. Hence, it is worried that the total number of on-orbit objects including currently recognized debris may swell by several times. 
     Assume that in a mega-constellation satellite group, a satellite group consisting of up to several thousand satellites flies on the same orbit, as illustrated in  FIG.  3   . On a polar orbit having an orbital inclination of almost 90°, a satellite density is high in polar regions where all orbital planes meet. Therefore, the mega-constellation business device  41  must conduct strict passing timing control for ensuring flight safety. 
     Meanwhile, as illustrated in  FIG.  4   , on an inclined orbit having an orbital inclination far from 90°, a collision risk exists at an orbital-plane intersection in a middle-latitude region. Therefore, to ensure flight safety by shifting a satellite passing timing at every lattice intersection, the mega-constellation business device  41  must conduct strict passing timing control. 
     In this manner, in order to realize strict passing timing control, the individual satellite groups fly while constantly operating the propulsion devices  33 . 
     A procedure of ensuring flight safety requires performing danger analysis first of all, such as approach analysis and collision analysis. To perform high-accuracy danger analysis, high-accuracy orbital information of a space object is indispensable. 
     As described above, however, in mega-constellation satellite groups, the individual satellite groups fly while constantly operating the propulsion devices, in order to realize strict passing timing control. Hence, accurate position information cannot be grasped unless the orbital information is updated in a real-time manner. It is rational to consider that it is only mega-constellation business operators which manage individual mega-constellation satellite groups that can manage real-time high-accuracy orbital information of several hundred to several ten-thousand satellites. 
     Furthermore, it is supposed to be difficult to share real-time high-accuracy orbital information among different business operators. 
     In view of this, it is rational to proceed as follows. Information of a region where the mega-constellation satellite group flies is disclosed and shared, instead of the real-time high-accuracy orbital information of the individual satellites of the mega-constellation satellite group at a steady operation stage. After the information of the region where the mega-constellation satellite group flies is disclosed and shared, if passing of an unsteady space object is predicted, information of this passing is shared among stakeholders as a danger alarm. Then, high-accuracy orbital information of the unsteady space object is transmitted to the mega-constellation business operator that is in steady operation. The mega-constellation business operator itself which manages the real-time high-accuracy orbital information of the mega-constellation satellite group performs danger analysis. 
     It is assumed that as the number of on-orbit objects including those from generation shift of the mega-constellation satellite group increases greatly, the number of space objects in the orbit insertion stage and deorbit stage will increase greatly. Hence, it is assumed that a collision avoidance assist business will also appear which manages and shares these pieces of information among the stakeholders, performs danger analysis, and announces a danger alarm. It would be possible that an SSA business operator takes charge of this role. 
     In the procedure of ensuring flight safety, a collision avoidance countermeasure is particularly important when a danger of collision is predicted. A geostationary-orbit satellite conventionally avoids collision by operating its own propulsion device in response to a danger alarm from CSpOC. 
     However, since the mega-constellation satellite group is under strict timing management as described above, the safety is not always guaranteed by a collision avoidance action of an individual satellite alone. This is because as a result of the avoidance action, a risk of collision with another satellite arises. 
     Hence, for avoiding collision with an individual satellite, sometimes it may be rational to take a collision avoidance action by synchronously controlling part or a whole of the mega-constellation satellite group. 
     There is also a possibility that an unstably operating space object takes an avoidance action. However, there may be a case where the unsteady-operation space object is not provided with a propulsion device, or is not provided with an avoidance action function because, for example, a provided propulsion device is function-suspended or has failed. 
     In rocket launch, it is possible to take a collision avoidance countermeasure of optimizing a launch timing. However, real-time high-accuracy orbital information of the mega-constellation satellite group is indispensable even when optimizing the launch timing. Furthermore, it is almost impossible to set a launch timing that guarantees flight safety for all of a plurality of mega-constellation satellite groups. 
       FIG.  17    is a diagram illustrating an example of launching a rocket to a region of a mega-constellation satellite group according to the present embodiment. 
       FIG.  18    is a diagram illustrating an example of a flight image of a mega-constellation satellite group near an altitude of 340 km according to the present embodiment.  FIG.  18    illustrates an example of a safe region in rocket launch. 
     There is a mega-constellation business operator that proclaims being provided with an automatic collision preventive function. However, as a method of practicing the automatic collision preventive function or its algorithm is not disclosed, it is difficult for a third party to estimate behavior of satellites of that mega-constellation business operator. 
     As described above, in a stage of launching individual satellites constituting the mega-constellation satellite group and deploying the individual satellites on orbits, the satellites must pass through an orbital-altitude region where a mega-constellation satellite group managed by another business operator flies. Furthermore, in a deorbit period after completion of a mission on an orbit until atmospheric entry, the satellites must pass through an orbital-altitude region where the mega-constellation satellite group managed by another business operator flies. 
     Therefore, a framework is required that enables mega-constellation business operators to avoid satellite collision with each other at an unsteady operation stage such as orbit insertion and orbital disposal so that flight safety is ensured. 
     Many mega-constellation business operators are, so to speak, in the same boat. For each mega-constellation business operator, another mega-constellation business operator exists in both at a higher altitude and a lower altitude than its own system. In such a case, a contradictory situation occurs which involves a risk that a high-altitude satellite in deorbiting might intrude into a lower-altitude flight region of another business operator, and a risk that a new satellite being put into orbit by rocket launch might intrude into a higher-altitude flight region of another business operator. 
     In the example of  FIG.  12   , for each of the mega-constellation business operators A, B, and C, a satellite group of another business operator exists at a higher altitude than its own satellite group, and a satellite group of another business operator exists at a lower altitude than its own satellite group. 
     Therefore, which is the offender and which is the casualty cannot be one-sidedly determined with respect to a responsibility for avoiding collision when an unsteady space object intrudes into a steady operation orbit and with respect to an accountability for an accident in the event of collision. The positions of the business operator A, the business operator B, and the business operator C can be reversed anytime. Hence, without a framework where a plurality of mega-constellation business operators can coexist and prosper together, it is difficult to guarantee sustainability of mega-constellation businesses. 
     As a feature of a mega-constellation, quite a large number of satellites fly in the same-orbit altitude zone. Therefore, a high risk of a collision accident leading to chained collision must be considered. 
     It is very dangerous if a mega-constellation operator believes that “even if some out of many satellites fail, there is no problem because the service as a satellite group can be continued”. Business operators should address collision avoidance considering that the whole space business will be suspended if chained collision does not stop to cause a Kessler syndrome. 
     In view of the above situation, in the present embodiment, orbital information of the mega-constellation satellite group at the steady operation stage and space object information at the unsteady operation stage are shared among business devices of related stakeholders. Then, the collision avoidance assist business device or the SSA business device announces a danger alarm, and the steady-operation mega-constellation business device side carries out danger analysis using the real-time high-accuracy orbital information. When a danger of collision is predicted, the steady operation mega-constellation business device formulates a collision avoidance action plan and shares information of the plan with the business devices of the related stakeholders. 
     At first glance, the unsteady space object side seems to be a “troubling side”, and the steady operation mega-constellation side seems to be a “troubled side”. However, since the mega-constellation business operators which are in the same boat are faced with the same problem, they should cooperate to realize a space traffic management system that ensures flight safety. 
     This situation is commonly observed anywhere in the world regardless of a difference in position such as a company, a nation, and a race or ethnic group. It is expected that even a mega-constellation concept that is currently unknown is to realize a space traffic management system having the same scheme so that coexistence and co-prosperity and conservation of space environment as a public good are achieved. 
     &lt;Function of Space Traffic Management System  500 &gt; 
     Function configuration examples of the space traffic management system  500  according to the present embodiment will now be described with referring to  FIGS.  19  to  21   . The hardware configurations of the individual space traffic management devices  100  have been described above. 
     The plurality of space traffic management devices  100  provided to the space traffic management system  500  are connected to each other via a communication line  200 . The space traffic management devices  100  are individually provided to the plurality of mega-constellation business devices  41  and the collision avoidance assist business device  43 .  FIG.  19    illustrates mega-constellation business devices A and B as the plurality of mega-constellation business devices  41 . 
       FIG.  19    is a diagram illustrating an overall configuration example of the space traffic management system  500  according to the present embodiment. 
       FIG.  20    is a diagram illustrating a detailed configuration example of the space information recorder  101  of the collision avoidance assist business device  43  according to the present embodiment. 
       FIG.  21    is a diagram illustrating a detailed configuration example of the space information recorder  101  of the mega-constellation business device  41  according to the present embodiment. 
       FIG.  19    illustrates the configuration in detail of the space traffic management device  100  of only the mega-constellation business device B. However, the mega-constellation business devices A and the mega-constellation business device B have space traffic management devices  100  of the same configuration. 
       FIG.  21    illustrates the space information recorder  101  of the mega-constellation business device B. 
     &lt;Mega-Constellation Business Device  41 &gt; 
     The space traffic management device  100  of the mega-constellation business device  41  is provided with the space information recorder  101 , a danger alarm device  102 , a danger analysis device  103  which performs orbital analysis of a space object, a danger avoidance action assist device  104 , and a danger avoidance action implementation plan information  105 . 
     The space information recorder  101  of the mega-constellation business device  41  records orbital information of satellites constituting a mega-constellation. 
     The space information recorder  101  is provided with public orbital information  61  associated with a satellite group ID that identifies a satellite group, and real-time high-accuracy orbital information  64  associated with a satellite ID that identifies a satellite. The space information recorder  101  is also provided with unsteady orbital information  63  associated with a satellite ID that identifies an unsteady-operation satellite. 
     The public orbital information  61  is orbital information that can be disclosed to the other business devices. Constituent satellite information such as a number of satellites constituting the satellite group and satellite IDs of the satellites, an upper limit and lower limit of an orbital altitude of the satellite group, and an upper limit and lower limit of an orbital inclination of the satellite group are set in the public orbital information  61 . 
     The real-time high-accuracy orbital information  64  consists of predicted orbital information and performance orbital information of each of the satellites constituting the satellite group. A specific example of the predicted orbital information is the orbit prediction information  51  of  FIG.  11   . 
     The danger alarm device  102  announces approach or danger of collision of a space object. The danger alarm device  102  is provided with orbital information associated with a space object ID that identifies a space object. The danger alarm device  102  is also provided with public condition information in which a public condition of the orbital information is set. 
     The danger analysis device  103  performs orbital analysis of the space object. For example, the danger analysis device  103  is an example of the collision analysis unit  411  that analyzes collision of an unsteady-operation space object with an individual satellite constituting a mega-constellation satellite group. That is, the server  212  provided to the space traffic management device  100  of the mega-constellation business device  41  analyzes collision of the unsteady-operation space object with the individual satellite constituting the mega-constellation satellite group. 
     The danger avoidance action assist device  104  formulates role division of an avoidance action against a space object. For example, the danger avoidance action assist device  104  is an example of the countermeasure formulating unit  412  that formulates a collision avoidance countermeasure when collision of a mega-constellation with an unsteady-operation space object is predicted. That is, the server  212  provided to the space traffic management device  100  of the mega-constellation business device  41  formulates a collision avoidance countermeasure when collision is predicted. 
     An avoidance action plan formulated by the danger avoidance action assist device  104  is set in the danger avoidance action implementation plan information  105 . 
     The predicted orbital information and the performance orbital information are set in the real-time high-accuracy orbital information  64  to correspond to the satellite ID. The predicted orbital information and the performance orbital information are set in a real-time manner and accurately. 
     Predicted orbital information about a space object which performs unsteady operation in an own mega-constellation is set in the unsteady orbital information  63 . An epoch, orbital elements, and predicted errors are set in the predicted orbital information, as in  FIG.  11   . 
     &lt;Collision Avoidance Assist Business Device  43 &gt; 
     The space traffic management device  100  of the collision avoidance assist business device  43  is provided with a space information recorder  101 , a danger alarm device  102 , and a danger analysis device  103 . 
     The database  211  provided to the space traffic management device  100  of the collision avoidance assist business device  43  records orbital information, acquired from the plurality of mega-constellation business devices  41 , of the mega-constellation satellite group during steady operation, and orbital information of the unsteady-operation space object. Specifically, the space information recorder  101  of the collision avoidance assist business device  43  records the public orbital information  61 , acquired from the mega-constellation business devices A and B, of the mega-constellation satellite group, and the unsteady orbital information  63  of the unsteady-operation space object. 
     The public orbital information  61  is orbital information, acquired from the mega-constellation business devices A and B, of the mega-constellation satellite group during steady operation. 
     The unsteady orbital information  63  is orbital information of the unsteady-operation space object. 
       FIG.  20    illustrates the configuration in detail of the unsteady orbital information  63  of only the space object A. However, each of space objects B and of C has the same configuration as that of the unsteady orbital information  63 . Also,  FIG.  20    illustrates the configuration in detail of the public orbital information  61  of only the mega-constellation business device A. However, each of the other mega-constellation satellite groups B and C has the same configuration as this. 
     In  FIG.  20   , the collision avoidance assist business device  43  acquires the unsteady orbital information  63  of the mega-constellation satellite group B and the public orbital information  61  of the mega-constellation satellite group B, from the mega-constellation satellite group B. Likewise, the collision avoidance assist business device  43  acquires the unsteady orbital information  63  of the space object A and the public orbital information  61  of the mega-constellation satellite group A, from the mega-constellation satellite group A. 
     An unsteady-operation space object is an unsteady-operation individual satellite, or a new launch rocket to be launched newly. The unsteady-operation individual satellite includes an individual satellite inserted in an orbit, or an individual satellite that deorbits. 
     The danger analysis device  103  of the collision avoidance assist business device  43  performs orbital analysis of a space object. The danger analysis device  103  is an example of the orbital analysis unit  431  that identifies a mega-constellation satellite group formed in an orbital altitude which the mega-constellation satellite group is anticipated to pass during a flight of the unsteady-operation space object. That is, the server  212  provided to the space traffic management device  100  of the collision avoidance assist business device  43  identifies a mega-constellation satellite group formed in an orbital altitude which the mega-constellation satellite group is anticipated to pass during a flight of the unsteady-operation space object. 
     The danger alarm device  102  of the collision avoidance assist business device  43  announces danger of approach or collision of a space object. The danger alarm device  102  is an example of the announcement unit  432  that announces a danger alarm and the unsteady orbital information  63  of an unsteady-operation space object, when it is predicted that an unsteady-operation space object intrudes into an orbital-altitude region where a mega-constellation satellite group flies. That is, the server  212  provided to the space traffic management device  100  of the collision avoidance assist business device  43  announces a danger alarm and orbital information of an unsteady-operation space object to the mega-constellation business device  41  which manages a mega-constellation satellite group. 
     Description of Operations 
       FIG.  22    is a flowchart illustrating a space traffic management process of the space traffic management system  500  according to the present embodiment. The orbital analysis unit  431  and the announcement unit  432  are provided to the server of the space traffic management device  100  of the collision avoidance assist business device  43 . The collision analysis unit  411  and the countermeasure formulating unit  412  are provided to the server of the space traffic management device  100  of the mega-constellation business device  41 . 
     In step S 101 , the space traffic management device  100  of the collision avoidance assist business device  43  receives the unsteady orbital information  63  of an unsteady-operation space object S and the public orbital information  61  of a mega-constellation satellite group, from the plurality of mega-constellation business devices  41  via the communication line  200 . The public orbital information  61  may be recorded in advance in a database of the space traffic management device  100  of the collision avoidance assist business device  43 . 
     The database of the space traffic management device  100  of the collision avoidance assist business device  43  records unsteady orbital information  63  of the steady-operation space object S, and public orbital information  61  in which orbital information or flight region information of the mega-constellation satellite group is set. 
     In step S 102 , the orbital analysis unit  431  identifies a mega-constellation satellite group formed in an orbital altitude which the mega-constellation satellite group is anticipated to pass during the flight of the unsteady-operation space object S. 
     In step S 103 , if it is predicted that the unsteady-operation space object S intrudes into an orbital altitude region where satellite groups of a mega-constellation fly, the processing proceeds to step S 104 . 
     In step S 104 , the announcement unit  432  announces a danger alarm and the unsteady orbital information  63  of the unsteady-operation space object S, to the mega-constellation business operator via the communication line  200 . Specifically, the announcement unit  432  transmits the danger alarm and orbital information of the unsteady-operation space object in the identified mega-constellation satellite group to the space traffic management device  100  of a business operator that is different from the business operator that manages the space object S. 
     In step S 105 , the collision analysis unit  411  analyzes collision of the unsteady-operation space object S with an individual satellite constituting the mega-constellation satellite group. The collision analysis unit  411  analyzes collision of the space object S with the individual satellite constituting the mega-constellation satellite group, with using the unsteady orbital information  63  of the space object S and the orbital information of the satellite group which is recorded in the space information recorder  101  of its own device. 
     In step S 106 , if collision is predicted, the processing proceeds to step S 107 . In step S 107 , the countermeasure formulating unit  412  formulates a collision avoidance countermeasure to avoid collision of the unsteady-operation space object S with the satellite constituting the mega-constellation satellite group. The collision avoidance countermeasure is set in the danger avoidance action implementation plan information  105  of the mega-constellation business device  41 . 
     Regarding the collision avoidance countermeasure, in a case where the unsteady-operation space object S is not provided with a control device or a provided control device has failed, the steady-operation mega-constellation satellite group must take a collision avoidance action. In this case, it is effective to use an effect of the following procedure. All or some of the propulsion devices of the mega-constellation satellite group are operated in a traveling direction to perform acceleration, thereby raising trajectory altitude. As a result, the ground speed decreases and the orbital position change. After the unsteady-operation space object S passes safely, the propulsion devices are operated to achieve propulsion in a direction opposite to the traveling direction. Consequently, the trajectory altitude is lowered and the ground speed increases, so that the mega-constellation satellite group can return to the original flying position. 
     As described above, the mega-constellation business device performs collision analysis on the basis of an acquired danger alarm, and after collision is predicted, executes a collision avoidance action. In other words, the mega-constellation business device executes a collision avoidance action on the basis of a collision avoidance countermeasure formulated by the space traffic management method of the space traffic management system. 
     The mega-constellation business operator operates the propulsion devices provided to the individual satellites in order to perform acceleration or deceleration, thereby raising or lowering the trajectory altitude. The mega-constellation business operator sync-controls all the satellite groups having the same nominal orbital altitude so that the satellite groups execute the same operation. Thus, the mega-constellation business operator can execute a collision avoidance action while almost maintaining a relative relationship among mega-constellation satellite groups. 
     If satellites having orbital planes with normals in different directions fly at the same altitude, there is a risk of collision to occur on an intersection line of the orbital planes within its own system. Hence, the mega-constellation business device is required to perform analysis of collision within its own system and to find an optimum passing timing for risk avoidance. This collision analysis is however difficult for the other business operators to perform. 
     Another method to implement the collision avoidance action can include a means of sync-controlling only a satellite group on a particular orbital plane to conduct similar operations, or a means of taking a collision avoidance action for only a satellite whose collision is predicted. 
     Yet, collision analysis for avoiding collision of the mega-constellation satellite groups to occur within its own system is required likewise. 
     A collision avoidance assist business operator may be an SSA business operator. That is, the collision avoidance assist business device  43  may be an SSA business device utilized by an SSA business operator. 
     Other Configurations 
     Description will be made below on functional examples of a space traffic management system in which space traffic management devices individually mounted in a collision avoidance assist business device, a plurality of mega-constellation business devices for managing mega-constellations, and an SSA business device are connected to each other via a communication line. 
     &lt;Functional Example 1&gt; 
     A collision avoidance assist business device performs danger analysis using orbital information, acquired from a first mega-constellation business device, of a mega-constellation satellite group in steady operation, orbital information, acquired from a second mega-constellation business device, of an unsteady-operation individual satellite, or orbital information of a new launch rocket, and announces a danger alarm and orbital information of a space object to the mega-constellation business devices. 
     &lt;Functional Example 2&gt; 
     An SSA business device serves as a collision avoidance assist business device as well. The SSA business device performs danger analysis using orbital information, acquired from a plurality of mega-constellation business devices, of a mega-constellation satellite group in steady operation, orbital information of an unsteady-operation individual satellite, or orbital information of a new launch rocket, and announces a danger alarm and orbital information of a space object to the mega-constellation business devices. 
     &lt;Functional Example 3&gt; 
     A mega-constellation business device discloses orbital information of a mega-constellation satellite group in steady operation to a collision avoidance assist business device or an SSA business device, and acquires a danger alarm and orbital information of a space object from the collision avoidance assist business device or the SSA business device. 
     &lt;Functional Example 4&gt; 
     A mega-constellation business device discloses orbital information of an unsteady-operation individual satellite to a collision avoidance assist business device or an SSA business device, and acquires a danger alarm from the collision avoidance assist business device, another mega-constellation business device, or the SSA business device. 
     &lt;Functional Example 5&gt; 
     A mega-constellation business device discloses orbital information of a new launch rocket to a collision avoidance assist business device or an SSA business device, and acquires a danger alarm from the collision avoidance assist business device, another mega-constellation business device, or the SSA business device. 
     &lt;Functional Example 6&gt; 
     A mega-constellation business device discloses orbital information of an unsteady-operation individual satellite among constituent satellites of a first mega-constellation satellite group of a first mega-constellation business device, or orbital information of a new launch rocket, to a second mega-constellation business device, and acquires a danger alarm from the second mega-constellation business device, a collision avoidance assist business device, or an SSA business device. 
     In the present embodiment, the functions of the space traffic management device  100  are implemented by software. A modification may be possible in which the functions of the space traffic management device  100  are implemented by hardware. 
     With referring to  FIG.  23   , a hardware configuration of a space traffic management device  100  according to a modification of the present embodiment will be described. Using a space traffic management device  100  of a mega-constellation business device  41  as an example, the hardware configuration of the space traffic management device  100  will be described. Note that space traffic management devices  100  of other business devices  40  have the same hardware configuration. 
     As described above, the space traffic management device  100  of the mega-constellation business device  41  is provided with the collision analysis unit  411 , the countermeasure formulating unit  412 , and the storage unit  140 , as examples of function elements that implement the mega-constellation management function. 
     The space traffic management device  100  is provided with an electronic circuit  909  in place of a processor  910 . 
     The electronic circuit  909  is a dedicated electronic circuit that implements the functions of the space traffic management device  100 . 
     The electronic circuit  909  is specifically a single circuit, a composite circuit, a programmed processor, a parallel-programmed processor, a logic IC, a GA, an ASIC, or an FPGA. GA stands for Gate Array. 
     The functions of the space traffic management device  100  may be implemented by one electronic circuit, or may be distributed among a plurality of electronic circuits and implemented by them. 
     Another modification may be possible in which some of the functions of the space traffic management device  100  are implemented by an electronic circuit and the remaining functions are implemented by software. 
     A processor and an electronic circuit are called processing circuitry as well. That is, the functions of the space traffic management device  100  are implemented by processing circuitry. 
     Description of Effect of Present Embodiment 
     A mega-constellation satellite group constantly operates propulsion devices to intentionally conduct orbit control. Accordingly, to conduct high-accurate collision analysis, real-time high-accuracy orbital information must be used. However, it is reasonable to assume that only a mega-constellation business device that manages the relevant mega-constellation satellite group can grasp this information. 
     There is a case where a satellite at an unsteady operation stage which is possessed by a different mega-constellation business operator intrudes into a region where the mega-constellation satellite group flies. In this case, it is difficult for a mega-constellation business device to hold real-time high-accuracy orbital information possessed by a different business device, together with real-time high-accuracy orbital information of a satellite group of its own system, and to perform collision analysis. 
     In the present embodiment, business devices of a plurality of mega-constellation business operators and a business device of a collision avoidance assist business operator are provided with space traffic management devices. The space traffic management devices are connected to each other via a communication line in order to set up an environment that allows information sharing. 
     Furthermore, a database provided to the collision avoidance assist business operator records, in the database, a region where a plurality of mega-constellation satellite groups fly. In the space traffic management devices, this database is also called a space information recorder. 
     The collision avoidance assist business device acquires orbital information of an unsteady-operation individual satellite, such as a new satellite at an orbit insertion stage and a satellite at a deorbit stage after mission completion, from the mega-constellation business operator, and records the orbital information to the space information recorder. The collision avoidance assist business device also records launch orbital information of a rocket to be launched newly, to the space information recorder. 
     A danger analysis device is mounted in the space traffic management device provided to the collision avoidance assist business device. The danger analysis device identifies a mega-constellation satellite group flying at an orbital altitude which an unsteady-operation satellite or a new launch rocket passes on its flight route. The collision avoidance assist business device transmits a danger alarm and orbital information of the unsteady-operation space object in the identified mega-constellation business satellite group, to a space traffic management device of a business operator different from a business operator of the unsteady-operation space object. 
     The mega-constellation business device having acquired the danger alarm analyzes collision with the relevant unsteady space object with using real-time high-accuracy information of a mega-constellation satellite group which the mega-constellation business device manages. 
     When collision is predicted, the mega-constellation business device controls the mega-constellation satellite group it possesses, and formulates a plan for collision avoidance. 
     As described above, when the unsteady-operation space object is not provided with a control device or a provided control device has failed, the steady-operation mega-constellation satellite group takes a collision avoidance action. 
     In the case of a new rocket launch, a countermeasure of avoiding collision with the mega-constellation satellite group by controlling a launch timing may be possible. However, it is difficult to avoid collision in all flight regions of a plurality of mega-constellation satellite groups by timing control alone. 
     With the space traffic management system according to the present embodiment, when an unsteady-operation space object intrudes into a flight region of a steady-operation satellite group which is managed by a different business operator, real-time high-accuracy orbital information of both sides can be shared with the collision avoidance assist business device. This information sharing has an effect of enabling high-accuracy collision analysis. For example, assume that if an unsteady-operation space object is managed by a mega-constellation business operator A, a steady-operation mega-constellation satellite group is managed by a mega-constellation business operator B which is different from the mega-constellation business operator A. 
     With the space traffic management system according to the present embodiment, when collision is predicted, an appropriate collision avoidance countermeasure can be formulated, achieving an effect of collision avoidance. 
     Embodiment 2 
     In the present embodiment, a difference from Embodiment 1 and an additional point to Embodiment 1 will mainly be described. 
     In the present embodiment, a configuration having the same function as in Embodiment 1 will be denoted by the same reference sign, and its description will be omitted. 
     Due to emergence of mega-constellation business operators, currently, several thousand satellites fly at an orbital altitude of 500 km or less as if to exhaustively cover the sky. This poses a high risk of collision of a satellite in a process of deorbiting from a high altitude with a low-altitude satellite, collision of a low-altitude satellite with a new launch rocket, or collision of satellites with each other both during geostationary-orbital transfer. Above all, in order that different mega-constellation satellite groups coexist, a framework is required for each business operator to avoid collision with an unsteady space object intruding into a steady-operation satellite group. Hence, a framework is required in which a collision avoidance assist business operator issues a danger alarm and mega-constellation business operators perform collision analysis and collision avoidance. 
     Studies have been in progress on building a public information system called open architecture data repository (OADR) which allows business operators to share orbital information of a space object so that flight safety of the space object is ensured. 
     The present embodiment will describe a mode of ensuring flight safety of a space object by the public information system called OADR. 
     When setting up an OADR as a public institution of international cooperation, there is a possibility that the OADR is authorized to make an instruction or request to a business operator beyond borders. 
     For example, in central management of orbital information of space objects possessed by business operators around the world, it is rational if the OADR can make an instruction or a request to provide orbital information under a rule based on an international consensus. 
     When a particular country sets up an OADR as a public institution, there is a possibility that the OADR is authorized to make an instruction or request to business operators of the relevant country. 
     There is also a possibility that the OADR forms a framework of disclosing information to business operators of the relevant country unconditionally while disclosing information conditionally to the other business operators. 
     As a public condition, it is possible to set, for example, fee charging, price setting, disclosure item restriction, accuracy restriction of public information, disclosure frequency restriction, and non-disclosure to a specific business operator. 
     For example, a difference of no charging or fee charging, or a difference in an amount of fee for information acquisition may arise between the relevant country and other countries. How the public condition is set by the OADR affects framework making for space traffic management or industrial competitive power. 
     It is rational that, regarding space-object confidential information which serves security, the OADR being set up by a country as a public institution possesses the confidential information but keeps the confidential information closed to the outside. Therefore, there is a possibility that the OADR is provided with a database for storing non-public information, in addition to a database for information disclosure. 
     In addition, among pieces of space object information possessed by private business operators, there is information that cannot be disclosed to the public because, for example, the information belongs to a corporate secret. In addition, there is information that is not appropriate for public disclosure, because the information is under constant maneuver control and accordingly an amount of information or an update frequency of the information becomes enormous. 
     When conducting danger analysis and analysis evaluation related to approach or collision of a space object, it is necessary that orbital information of all space objects be dealt with regardless of whether the space object is confidential or not. For this reason, when the OADR as a public institution conducts danger analysis including confidential information and danger is predicted as a result of analysis evaluation, it is rational to restrict a publication target or a publication content and to conduct conditional disclosure. For example, it is rational to restrict the publication target or a publication content and to conduct conditional disclosure by processing information into disclosable information, and disclosing only orbital information of a risky timeframe to a disclosure target that contributes to danger avoidance. 
     In the future, when the number of on-orbit objects increases and the risk of approach or collision increases, various danger avoidance countermeasures will be needed, such as means with which a debris removal business operator removes dangerous debris, and means with which a mega-constellation business operator changes an orbital position or a passing timing so as to avoid collision. If the OADR, being a public institution, can instruct or request a business operator to execute a danger avoidance action, a tremendous effect can be expected in ensuring flight safety of space. 
     There are space objects managed by an institution, such as an emerging country venture business operator or a university, that is inexperienced in the space business and lacks information that serves danger avoidance. When it is predicted that a space object managed by such an institution which is inexperienced in the space business and lacks information that serves danger avoidance will intrude into an orbital altitude zone where a mega-constellation flies, the OADR intermediates to transmit the relevant information to the business operator in need of the information, so that the danger can be avoided quickly and effectively. 
     In addition, mediation or introduction of implementation of a danger avoidance countermeasure or space insurance to private business operators will contribute to promotion and industrialization of space traffic management. 
     The OADR may be realized in the following modes.
         A mode where the OADR is provided with only a public database.   A mode where the OADR possesses a danger analysis means, a collision avoidance assist means, or a space situational awareness (SSA) means to positively contribute to danger avoidance independently.   A mode where the OADR gives an instruction or a request to a business operator, or performs mediation or introduction to a business operator, thus contributing to danger avoidance through information management.       

     For realizing the OADR, there are various possibilities other than the above-mentioned modes. 
     “The OADR mediates implementation of a space traffic management method” signifies a case where, for example, an entity implementing the space traffic management method includes a plurality of external business devices other than the OADR, and the OADR does not issue a compulsory order but encourages implementation of the method by intermediating among the plurality of business devices. “The OADR mediates implementation of the space traffic management method” is paraphrased as, for example, “the OADR intermediates so that a plurality of external business devices other than the OADR cooperate with each other to implement a space traffic management method”. Alternatively, “mediation” may be replaced with “teaching”. 
     A configuration example of the OADR according the present embodiment will be described below. 
     &lt;Configuration Example 1 of OADR&gt; 
       FIG.  24    illustrates an OADR  800  as Configuration Example 1 according to the present embodiment. 
     The OADR  800  is a public information system to disclose orbital information of a space object. The OADR  800  is provided with a database  810  to store the orbital information of the space object, and a server  820 . 
     The database  810  is provided with a first database  811  to store public information and a second database  812  to store non-public information. 
     The server  820  acquires space object information including non-public information from all or some of business devices which are: a space traffic management device; a space situational awareness business device (SSA business device); a collision avoidance assist business device; a mega-constellation business device; and a debris removal business device, and stores the acquired space object information to the second database  812 . The space traffic management device is provided to, for example, CSpOC. 
     Conventionally, the U.S. CSpOC is not provided with a bi-directional line, and announces a danger alarm uni-directionally. If is provided with a space traffic management device, CSpOC can contribute to space traffic management by communication of the space traffic management device with the other business devices via a bi-directional communication line. 
     The server  820  generates conditional public information with restricted publication target and restricted publication content and stores the generated information to the first database  811 . 
     Then, the server  820  transmits the conditional public information only to a particular business device among the SSA business device, the collision avoidance assist business device, the mega-constellation business device, the debris removal business device, and a space insurance business device which deals with a space insurance. 
     The OADR  800  of Configuration Example 1 mediates implementation of the space traffic management method described in Embodiment 1 while implementing the above functions. 
     There is a possibility that space object confidential information possessed by CSpOC and serving safety security is disclosed only to the OADR. Meanwhile, a risk of approach or collision must be analyzed to include the confidential information, and must be predicted. 
     After the information is processed into conditional disclosable information, the conditional public information which serves collision avoidance assist is shared only to a business device related to a collision risk. Hence, even a private business operator can take a collision avoidance action. 
     Among pieces of space object information possessed by the private business operators, regarding space object information that cannot be disclosed to the public, the OADR processes it into conditional disclosable information likewise, so that collision avoidance becomes possible. 
     &lt;Configuration Example 2 of OADR&gt; 
       FIG.  25    illustrates an OADR  800  as Configuration Example 2 according to the present embodiment. 
     The OADR  800  as Configuration Example 2 is provided with the collision avoidance assist business device described in Embodiment 1, in addition to Configuration Example 1. As illustrated in  FIG.  25   , a server  820  may be provided with a function of the collision avoidance assist business device. 
     The server  820  acquires space object information including non-public information from all or some of business devices which are: a space traffic management device; an SSA business device; another collision avoidance assist business device other than that of its own OADR; a mega-constellation business device; and a debris removal business device, and stores the acquired space object information to a second database  812 . The space traffic management device is provided to, for example, CSpOC. 
     Another collision avoidance assist business device is another collision avoidance assist business device other than the collision avoidance assist business device of the OADR  800 . 
     The server  820  generates conditional public information with restricted publication target and restricted publication content and stores the generated information to a first database  811 . 
     Then, the server  820  transmits the conditional public information only to a particular business device among the SSA business device, another collision avoidance assist business device, the mega-constellation business device, the debris removal business device, and a space insurance business device which deals with a space insurance. 
     When the OADR serves as a collision avoidance assist business operator as in Configuration Example 2, the same effect as that of Configuration Example 1 can be obtained. 
     &lt;Configuration Example 3 of OADR&gt; 
       FIG.  26    illustrates an OADR  800  as Configuration Example 3 according to the present embodiment. 
     The OADR  800  as Configuration Example 3 is provided with the SSA business device described in Embodiment 1, in addition to Configuration Example 1. The SSA business device is also called a space situational awareness business device that monitors space situation. As illustrated in  FIG.  26   , a server  820  may be provided with a function of the SSA business device. 
     The server  820  acquires space object information including non-public information from all or some of business devices which are: a space traffic management device; another SSA business device other than that of its own OADR; a collision avoidance assist business device; a mega-constellation business device; and a debris removal business device, and stores the acquired space object information to a second database  812 . The space traffic management device is provided to, for example, CSpOC. 
     Another SSA business device is another SSA business device other than the SSA business device of the OADR  800 . 
     The server  820  generates conditional public information with restricted publication target and restricted publication content and stores the generated information to a first database  811 . 
     Then, the server  820  transmits the conditional public information only to a particular business device among another SSA business device, the collision avoidance assist business device, the mega-constellation business device, the debris removal business device, and a space insurance business device which deals with a space insurance. 
     When the OADR serves as an SSA business operator as in Configuration Example 3, the same effect as in Configuration Example 1 and Configuration Example 2 can be obtained. 
     In above Embodiments 1 and 2, individual units in each of the space traffic management system, the space traffic management device, and the business device are described as independent function blocks. However, the space traffic management system, space traffic management device, and business device need not have configurations as in the embodiments described above. The function blocks in each of the space traffic management system and the space traffic management device may have any configurations as far as they can implement the functions described in the above embodiments. Also, each of the space traffic management system, the space traffic management device, and the business device may be one device, or may be a system constituted of a plurality of devices. 
     A plurality of parts out of Embodiments 1 and 2 may be practiced by combination. Alternatively, one part of these embodiments may be practiced. Also, these embodiments may be practiced as a whole or partly by any combination. 
     That is, in Embodiments 1 and 2, any parts out of Embodiments 1 and 2 can be combined arbitrarily, or an arbitrary constituent element can be modified. Also, in Embodiments 1 and 2, an arbitrary constituent element can be omitted. 
     The embodiments described above are essentially preferable exemplifications and are not intended to limit the scope of the present disclosure, the scope of an application product of the present disclosure, and the scope of use of the present disclosure. Various changes can be made to the embodiments described above as necessary. 
     REFERENCE SIGNS LIST 
       20 : satellite constellation;  21 : orbital plane;  211 : database;  212 : server;  30 : satellite;  31 : satellite control device;  32 : satellite communication device;  33 : propulsion device;  34 : attitude control device;  35 : power supply device;  40 : business device;  41 : mega-constellation business device;  411 : collision analysis unit;  412 : countermeasure formulating unit;  431 : orbital analysis unit;  432 : announcement unit;  42 : space object business device;  43 : collision avoidance assist business device;  44 : orbital transfer business device;  45 : debris removal business device;  46 : rocket launch business device;  47 : space insurance business device;  51 : orbit prediction information;  52 : satellite orbit prediction information;  53 : debris orbit prediction information;  511 : space object ID;  512 : predicted epoch;  513 : predicted orbital element;  514 : predicted error;  60 : space object;  70 : Earth;  100 : space traffic management device;  140 : storage unit;  55 : orbit control command;  61 : public orbital information;  63 : unsteady orbital information;  64 : real-time high-accuracy orbital information;  500 : space traffic management system;  600 : satellite constellation forming system;  11 ,  11   b : satellite constellation forming unit;  300 : satellite group;  700 ,  701 : ground facility;  510 : orbit control command generation unit;  520 : analytical prediction unit;  909 : electronic circuit;  910 : processor;  921 : memory;  922 : auxiliary storage device;  930 : input interface;  940 : output interface;  941 : display apparatus;  950 : communication device;  101 : space information recorder;  102 : danger alarm device;  103 : danger analysis device;  104 : danger avoidance action assist device;  105 : danger avoidance action implementation plan information;  200 : communication line;  800 : OADR;  810 : database;  811 : first database;  812 : second database;  820 : server.