Patent Publication Number: US-2023143771-A1

Title: Space traffic management system, space traffic management device, space traffic management method, collision avoidance assistance business device, satellite constellation business device, mega-constellation business device, space object business device, space situational awareness business device, and oadr

Description:
TECHNICAL FIELD 
     The present disclosure relates to a space traffic management system, a space traffic management device, a space traffic management method, a collision avoidance assistance business device, a satellite constellation business device, a mega-constellation business device, a space object business device, a space situational awareness business device, and an OADR. 
     BACKGROUND ART 
     In recent years, large-scale satellite constellations including several hundred to several thousand satellites, which are called mega-constellations, have started to be constructed, and the risk of collision between satellites in orbit is increasing. In addition, space debris such as an artificial satellite that has become uncontrollable due to a failure or rocket debris has been increasing. 
     With the rapid increase in space objects such as satellites and space debris in outer space as described above, in space traffic management (STM) there is an increasing need to create international rules for avoiding collisions between space objects. 
     Patent Literature 1 discloses a technology for forming a satellite constellation composed of a plurality of satellites in the same circular orbit. 
     There is so far a system in which the Combined Space Operations Center (CSpOC) in the United States continues to monitor space objects and issues an alert when a proximity or collision between space objects is foreseen. At a manned space station and in a commercial communications satellite, an avoidance operation is carried out in response to this alert when it is judged necessary. However, a plan to transfer the system to issue alerts for private satellites to a private business operator has recently been announced in the United States, and a new system is needed. 
     CITATION LIST 
     Patent Literature 
     Patent Literature 1: JP 2017-114159 A 
     SUMMARY OF INVENTION 
     Technical Problem 
     Satellites orbiting Earth includes a satellite whose orbit information is not appropriate to be disclosed or whose orbit information is kept secret. Such a satellite also has a risk of approaching and colliding with an individual satellite in a mega-constellation satellite group for which it is difficult to disclose high-precision orbit information in real time. A problem is that there is no scheme in which a collision can be foreseen without using public information in a satellite whose orbit information is not appropriate to be disclosed and an individual satellite in a mega-constellation satellite group, so that collision avoidance cannot be performed. 
     Patent Literature 1 does not describe a scheme for avoiding a collision between a satellite whose orbit information is not appropriate to be disclosed and an individual satellite in a mega-constellation satellite group. 
     An object of the present disclosure is to avoid a collision between a satellite whose orbit information is not appropriate to be disclosed and an individual satellite in a mega-constellation satellite group. 
     Solution to Problem 
     A space traffic management system according to the present disclosure is a system in which space traffic management devices installed respectively in a space object business device that manages a specific space object, a collision avoidance assistance business device that assists avoidance of a collision between space objects in outer space, and a satellite constellation business device that manages a satellite constellation composed of a plurality of satellites are connected with a communication line that is kept secret with a common cryptographic key, each of the space traffic management devices including a database and a server, 
     wherein the database included in the space traffic management device of the collision avoidance assistance business device records non-public orbit information of the specific space object that is received from the space object business device via the communication line that is kept secret and orbit information or flight region information of a satellite group of a satellite constellation that is acquired from the satellite constellation business device, 
     wherein the server included in the space traffic management device of the collision avoidance assistance business device includes 
     an orbit analysis unit to analyze an orbit of the specific space object, and 
     a notification unit to, when it is foreseen that the specific space object will intrude into an orbital altitude region where the satellite group of the satellite constellation flies, notify a satellite constellation business operator of an intrusion alert and the non-public orbit information of the specific space object via the communication line that is kept secret, and 
     wherein the server included in the space traffic management device of the satellite constellation business device includes 
     a collision analysis unit to analyze a collision between the specific space object and an individual satellite in the satellite group of the satellite constellation, and 
     a countermeasure planning unit to plan a collision avoidance countermeasure when a collision is foreseen. 
     Advantageous Effects of Invention 
     A space traffic management system according to the present disclosure can provide assistance to avoid a collision between a specific space object whose orbit information is not appropriate to be disclosed and a satellite group constituting a satellite constellation. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG.  1    is an example in which a plurality of satellites cooperatively realize a communication service to the ground over the entire globe of Earth; 
         FIG.  2    is an example in which a plurality of satellites in a single orbital plane realize an Earth observation service; 
         FIG.  3    is an example of a satellite constellation having a plurality of orbital planes that intersect in the vicinity of the polar regions; 
         FIG.  4    is an example of a satellite constellation having a plurality of orbital planes that intersect outside 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    is an example of a functional configuration of the satellite constellation forming system; 
         FIG.  9    is an example of a hardware configuration of a space traffic management device according to Embodiment 1; 
         FIG.  10    is a diagram illustrating an example of orbit forecast information according to Embodiment 1; 
         FIG.  11    is an example of a functional configuration of the space traffic management system according to Embodiment 1; 
         FIG.  12    is an example of a space information recorder of a mega-constellation business device according to Embodiment 1; 
         FIG.  13    is a flowchart illustrating a space traffic management process of the space traffic management system according to Embodiment 1; 
         FIG.  14    is an example of a hardware configuration of the space traffic management device according to a variation of Embodiment 1; 
         FIG.  15    is a diagram illustrating danger regions caused by a mega-constellation according to Embodiment 1; 
         FIG.  16    is an example of a functional configuration of the space traffic management system according to Embodiment 2; 
         FIG.  17    is a detailed configuration diagram of forecast orbit information according to Embodiment 2; 
         FIG.  18    is an example of a functional configuration of the space traffic management system according to Embodiment 3; 
         FIG.  19    is an example of a functional configuration of an OADR according to Embodiment 4; and 
         FIG.  20    is an example of the functional configuration of the OADR according to Embodiment 4. 
     
    
    
     DESCRIPTION OF EMBODIMENTS 
     Embodiments of the present disclosure will be described hereinafter with reference to the drawings. Throughout the drawings, the same or corresponding parts are denoted by the same reference signs. In the description of the embodiments, description of the same or corresponding parts will be suitably omitted or simplified. In the drawings hereinafter, the relative sizes of components may be different from actual ones. In the description of the embodiments, directions or positions such as “up”, “down”, “left”, “right”, “front”, “rear”, “top side”, and “back side” may be indicated. These terms are used only for convenience of description, and are not intended to limit the placement and orientation of components such as devices, equipment, or parts. 
     Embodiment 1 
     Examples of a satellite constellation assumed for a space traffic management system according to the following embodiments will be described. 
       FIG.  1    is a diagram illustrating an example in which a plurality of satellites cooperatively realize a communication service to the ground over the entire globe of Earth  70 . 
       FIG.  1    illustrates a satellite constellation  20  that realizes a communication service over the entire globe. 
     The ground communication service range of each satellite of a plurality of satellites flying at the same altitude in the same orbital plane overlaps the communication service range of a following satellite. Therefore, with such satellites, the satellites in the same orbital plane can provide a communication service to a specific point on the ground in turn in a time-division manner. By providing adjacent orbital planes, a communication service can be provided to the ground with widespread coverage across the adjacent orbits. Similarly, by placing a large number of orbital planes at approximately equal intervals around Earth, a communication service to the ground can be provided over the entire globe. 
       FIG.  2    is a diagram illustrating an example in which a plurality of satellites in a single orbital plane realize an Earth observation service. 
       FIG.  2    illustrates a satellite constellation  20  that realizes an 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 sensor such as a synthetic-aperture radar, fly at the same altitude in the same orbital plane. In this way, in a satellite group  300  in which the ground imaging ranges of successive satellites overlap in a time-delay manner, a plurality of satellites in orbit provide an Earth observation service by capturing ground images in turn in a time-division manner. 
     As described above, the satellite constellation  20  is formed with the satellite group  300  composed of a plurality of satellites in each orbital plane. In the satellite constellation  20 , the satellite group  300  cooperatively provides a service. Specifically, the satellite constellation  20  refers to a satellite constellation formed with one satellite group by a communications business service company as illustrated in  FIG.  1    or an observation business service company as illustrated in  FIG.  2   . 
       FIG.  3    is an example of a satellite constellation  20  having a plurality of orbital planes  21  that intersect in the vicinity of the polar regions.  FIG.  4    is an example of a satellite constellation  20  having a plurality of orbital planes  21  that intersect outside the polar regions. 
     In the satellite constellation  20  of  FIG.  3   , the orbital inclination of each of the plurality of orbital planes  21  is about 90 degrees, and the orbital planes  21  exist on mutually different planes. 
     In the satellite constellation  20  of  FIG.  4   , the orbital inclination of each of the plurality of orbital planes  21  is not about 90 degrees, and the orbital planes  21  exist on mutually different planes. 
     In the satellite constellation  20  of  FIG.  3   , any given two orbital planes intersect at points in the vicinity of the polar regions. In the satellite constellation  20  of  FIG.  4   , any given two orbital planes intersect at points outside the polar regions. In  FIG.  3   , a collision between satellites  30  may occur in the vicinity of the polar regions. As illustrated in  FIG.  4   , the intersections between the orbital planes each with an orbital inclination greater than 90 degrees move away from the polar regions according to the orbital inclination. Depending on the combinations of orbital planes, orbital planes may intersect at various locations including the vicinity of the equator. For this reason, places where collisions between satellites  30  may occur are diversified. A satellite  30  is referred to also as an artificial satellite. 
     In particular, in recent years, large-scale satellite constellations including several hundred to several thousand satellites have started to be constructed, and the risk of collision between satellites in orbit is increasing. In addition, space debris such as an artificial satellite that has become uncontrollable due to a failure or rocket debris has been increasing. A large-scale satellite constellation is referred to also as a mega-constellation. Such debris is referred to also as space debris. 
     As described above, with the increase in debris in outer space and the rapid increase in the number of satellites such as those in a mega-constellation, the need for space traffic management (STM) is increasing. 
     For an orbital transfer of a space object, there is an increasing need for deorbit after completion of a mission in orbit (PMD) or ADR, which causes debris such as a failed satellite or an upper stage of a rocket that is floating to deorbit by external means such as a debris retrieval satellite. International discussions have begun as STM on the need for such ADR. PMD is an abbreviation for Post Mission Disposal. ADR is an abbreviation for Active Debris Removal. 
     There is a specific space object which includes a satellite whose orbit information is not appropriate to be disclosed or whose orbit information is kept secret. It is difficult for a satellite group constituting a mega-constellation to disclose high-precision orbit information in real time. Therefore, there is a risk of proximity and collision between such a specific space object and an individual satellite in a mega-constellation satellite group. 
     In this embodiment, a scheme for avoiding a collision between a specific space object whose orbit information is not appropriate to be disclosed and an individual satellite in a mega-constellation satellite group will be described. 
     Referring to  FIGS.  5  to  8   , an example of a satellite  30  and a ground facility  700  in a satellite constellation forming system  600  that forms a satellite constellation  20  will be described. For example, the satellite constellation forming system  600  is operated by a business operator that conducts a satellite constellation business, such as a mega-constellation business device  41 , an LEO constellation business device, or a satellite business device. 
       FIG.  5    is a configuration diagram of the satellite constellation forming system  600 . 
     The satellite constellation forming system  600  includes a computer.  FIG.  5    illustrates a configuration with one computer but, in practice, a computer is provided in each satellite  30  of a plurality of satellites constituting the satellite constellation  20  and the ground facility  700  that communicates with each satellite  30 . The functions of the satellite constellation forming system  600  are realized cooperatively by the computers provided in each of the satellites  30  and the ground facility  700  that communicates with the satellites  30 . In the following, an example of a configuration of the computer that realizes the functions of the satellite constellation forming system  600  will be described. 
     The satellite constellation forming system  600  includes the satellite  30  and the ground facility  700 . The satellite  30  includes a satellite communication device  32  that communicates with a communication device  950  of the ground facility  700 . Among the components included in the satellite  30 , the satellite communication device  32  is illustrated in  FIG.  5   . 
     The satellite constellation forming system  600  includes a processor  910 , and also includes other hardware components 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 with other hardware components via signal lines and controls these other hardware components. The hardware of the satellite constellation forming system  600  is substantially the same as the hardware of a space traffic management device  100  to be described later with reference to  FIG.  9   . 
     The satellite constellation forming system  600  includes a satellite constellation forming unit  11  as a functional element. The functions of the satellite constellation forming unit  11  are realized by hardware or software. 
     The satellite constellation forming unit  11  controls formation of the satellite constellation  20  while communicating with the satellite  30 . 
       FIG.  6    is a configuration diagram of the satellite  30  of the satellite constellation forming system  600 . 
     The satellite  30  includes a satellite control device  31 , the satellite communication device  32 , a propulsion device  33 , an attitude control device  34 , and a power supply device  35 . Although other constituent elements that realize various functions are included, 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  will be described in  FIG.  6   . The satellite  30  is an example of a space object  60 . 
     The satellite control device  31  is a computer that controls the propulsion device  33  and the attitude control device  34  and includes a processing circuit. Specifically, the satellite control device  31  controls the propulsion device  33  and the attitude control device  34  in accordance with various 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 related to the satellite itself to the ground facility  700 . The satellite communication device  32  also receives various commands transmitted from the ground facility  700 . 
     The propulsion device  33  is a device that provides thrust force to the satellite  30  to change the velocity of the satellite  30 . Specifically, the propulsion device  33  is a chemical propulsion device or an electronic propulsion device. 
     The chemical propulsion device is a thruster using monopropellant or bipropellant fuel. The electronic propulsion device is an ion engine or a Hall thruster. 
     The attitude control device  34  is a device to control the attitude of the satellite  30  and attitude elements, such as the angular velocity and the line of sight, of the satellite  30 . The attitude control device  34  changes the orientation of each attitude element to a desired orientation. Alternatively, the attitude control device  34  maintains each attitude element in a desired orientation. The attitude control device  34  includes an attitude sensor, an actuator, and a controller. The attitude sensor is a device such as a gyroscope, an Earth sensor, a sun sensor, a star tracker, a thruster, or a magnetic sensor. The actuator is a device such as an attitude control thruster, a momentum wheel, a reaction wheel, or a control moment gyroscope. The controller controls the actuator in accordance with measurement data of the attitude sensor or various commands from the ground facility  700 . 
     The power supply device  35  includes equipment such as a solar cell, a battery, and an electric power control device, and provides electric power to each piece of equipment installed in the satellite  30 . 
     The processing circuit included in the satellite control device  31  will be described. 
     The processing circuit may be dedicated hardware, or may be a processor that executes programs stored in a memory. 
     In the processing circuit, some functions may be realized by hardware, and the remaining functions may be realized by software or firmware. That is, the processing circuit can be realized by hardware, software, firmware, or a combination of these. 
     Specifically, the dedicated hardware is a single circuit, a composite circuit, a programmed processor, a parallel-programmed processor, an ASIC, an FPGA, or a combination of these. 
     ASIC is an abbreviation for Application Specific Integrated Circuit. FPGA is an abbreviation for Field Programmable Gate Array. 
       FIG.  7    is a configuration diagram of the ground facility  700  included in the satellite constellation forming system  600 . 
     The ground facility  700  controls a large number of satellites in all orbital planes by programs. The ground facility  700  is an example of a ground device. The ground device is composed of a ground station, such as a ground antenna device, a communication device connected to a ground antenna device, or an electronic computer, and a ground facility as a server or terminal connected with the ground station via a network. The ground device may include a communication device installed in a mobile object such as an airplane, a self-driving vehicle, or a mobile terminal 
     The ground facility  700  forms the satellite constellation  20  by communicating with each satellite  30 . The ground facility  700  is provided in the space traffic management device  100 . The ground facility  700  includes a processor  910  and also includes other hardware components 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 with other hardware components via signal lines and controls these other hardware components. The hardware components of the ground facility  700  is substantially the same as the hardware components of the space traffic management device  100  to be described later with reference to  FIG.  9   . 
     The ground facility  700  includes an orbit control command generation unit  510  and an analytical prediction unit  520  as functional elements. The functions of the orbit control command generation unit  510  and the analytical prediction unit  520  are realized by hardware or software. 
     The communication device  950  transmits and receives signals for tracking and controlling each satellite  30  in the satellite group  300  constituting the satellite constellation  20 . The communication device  950  transmits an orbit control command  55  to each satellite  30 . 
     The analytical prediction unit  520  performs analytical prediction on the orbit of the satellite  30 . 
     The orbit control command generation unit  510  generates an orbit control command  55  to be transmitted to the satellite  30 . 
     The orbit control command generation unit  510  and the analytical prediction unit  520  realize the functions 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 an example of a functional configuration of the satellite constellation forming system  600 . 
     The satellite  30  further includes a satellite constellation forming unit  11   b  to form the satellite constellation  20 . The functions of the satellite constellation forming system  600  are realized cooperatively by the satellite constellation forming unit  11   b  included in each satellite  30  of a plurality of satellites and the satellite constellation forming unit  11  included in the ground facility  700 . The satellite constellation forming unit  11   b  of the satellite  30  may be included in the satellite control device  31 . 
     DESCRIPTION OF CONFIGURATIONS 
     A space traffic management system  500  according to this embodiment is a system aimed at avoiding a collision between a specific space object whose orbit information is not appropriate to be disclosed and a satellite in a mega-constellation satellite group. 
     The specific space object whose orbit information is not appropriate to be disclosed is, for example, a satellite whose orbit information is not appropriate to be disclosed or a satellite whose orbit information is kept secret. 
       FIG.  9    is a diagram illustrating an example of a hardware configuration of the space traffic management device  100  according to this embodiment. 
     The space traffic management device  100  is installed in each of business devices  40  of management business operators that manage space objects flying in space. 
     Specifically, the space traffic management device  100  is installed in each of the mega-constellation business device  41 , a space object business device  42 , and a collision avoidance assistance business device  43 . 
     The mega-constellation business device  41  manages a satellite constellation composed of a plurality of satellites. Specifically, the mega-constellation business device  41  is a computer of a mega-constellation business operator that conducts a large-scale satellite constellation, that is, mega-constellation business. The mega-constellation business device  41  is an example of a satellite constellation business device that manages, for example, a satellite constellation composed of 100 or more satellites. The satellite constellation composed of 100 or more satellites is referred to also as a mega-constellation. 
     The space object business device  42  manages a specific space object S. Specifically, the space object business device  42  is a computer of a space object business operator that manages the specific space object S. The specific space object S is, for example, a space object whose orbit information is not appropriate to be disclosed or whose orbit information is kept secret. 
     The collision avoidance assistance business device  43  assists avoidance of a collision between space objects in outer space. Specifically, the collision avoidance assistance business device  43  is a computer of a collision avoidance business operator that assists avoidance of a collision between space objects in outer space. 
     The space traffic management device  100  is installed in each of the mega-constellation business device  41 , the space object business device  42 , and the collision avoidance assistance business device  43 , and includes a database and a server. The space traffic management system  500  connects the space traffic management devices  100  installed respectively in the mega-constellation business device  41 , the space object business device  42 , and the collision avoidance assistance business device  43  with a secret communication line  200  that is kept secret with a common cryptographic key. The space traffic management devices  100  installed respectively in the mega-constellation business device  41 , the space object business device  42 , and the collision avoidance assistance business device  43  can communicate mutually via the secret communication line  200  and can also communicate via an ordinary communication line. 
     In addition to the mega-constellation business device  41 , the space object business device  42 , and the collision avoidance assistance business device  43 , the business devices  40  may also 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 an SSA business device. LEO is an abbreviation for Low Earth Orbit. SSA is an abbreviation for Space Situational Awareness. The SSA business device is referred to also as a space situational awareness business device. 
     Each of the business devices  40  provides information related to a space object  60  such as an artificial satellite managed by each device or debris. Each of the business devices  40  is a computer of a business operator that collects information related to a space object  60  such as an artificial satellite or debris. 
     The LEO constellation business device is a computer of an LEO constellation business operator that conducts a low Earth orbit constellation, that is, LEO constellation business. 
     The satellite business device is a computer of a satellite business operator that handles one to several satellites. 
     The orbital transfer business device is a computer of an orbital transfer business operator that performs a space object intrusion alert for satellites. 
     The debris removal business device is a computer of a debris removal business operator that conducts a business to retrieve debris. 
     The rocket launch business device is a computer of a rocket launch business operator that conducts a rocket launch business. 
     The SSA business device is a computer of an SSA business operator that conducts an SSA business, that is, a space situational awareness business. 
     The space traffic management device  100  may be installed in a ground facility  701  included in each of the business devices  40 . The space traffic management device  100  may be installed in the satellite constellation forming system  600 . 
     The space traffic management device  100  includes a processor  910  and also includes other hardware components 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 with other hardware components via signal lines and controls these other hardware components. 
     The processor  910  is an example of the server. The memory  921  and the auxiliary storage device  922  are examples of the database. The server may include other hardware components such as an input interface  930 , an output interface  940 , a communication device  950 , and a storage device. The server realizes the functions of each of the mega-constellation business device  41 , the space object business device  42 , and the collision avoidance assistance business device  43 . 
     The space traffic management device  100  of the collision avoidance assistance business device  43  includes an orbit analysis unit  431 , a notification unit  432 , and a storage unit  140  as an example of functional elements that realize a collision avoidance assistance function. In the storage unit  140 , orbit forecast information  51  and a cryptographic key  521  are stored. 
     The space traffic management device  100  of the mega-constellation business device  41  includes a collision analysis unit  411 , a countermeasure planning unit  412 , and a storage unit  140  as an example of functional elements that realize a mega-constellation management function. In the storage unit  140 , the orbit forecast information  51  and the cryptographic key  521  are stored. 
     The space traffic management device  100  of the space object business device  42  has a function of managing the specific space object S whose orbit information is not appropriate to be disclosed or whose orbit information is kept secret. 
     Referring to  FIG.  9   , a hardware configuration of the space traffic management device  100  will be described below, using the space traffic management device  100  of the collision avoidance assistance business device  43  as an example. It is assumed that the space traffic management devices  100  of other business devices  40  also have substantially the same hardware configuration. 
     The functions of the orbit analysis unit  431  and the notification unit  432  are realized by software. The storage unit  140  is provided in the memory  921 . Alternatively, the storage unit  140  may be provided in the auxiliary storage device  922 . Alternatively, the storage unit  140  may be divided and provided in the memory  921  and the auxiliary storage device  922 . 
       FIG.  9    will be described assuming that the space traffic management device  100  realizes the collision avoidance assistance function. However, the space traffic management device  100  has various functions other than the collision avoidance assistance function. 
     The processor  910  is a device that executes a space traffic management program. The space traffic management program is a program that realizes the functions of the constituent elements of the space traffic management device  100  and the space traffic management system  500 . 
     The processor  910  is an integrated circuit (IC) that performs operational 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 to temporarily store data. Specific examples of the memory  921  are a static random access memory (SRAM) and a dynamic random access memory (DRAM). 
     The auxiliary storage device  922  is a storage device to store 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, CF, a NAND flash, a flexible disk, an optical disc, a compact disc, a Blu-ray (registered trademark) disc, or a DVD. HDD is an abbreviation for Hard Disk Drive. SD (registered trademark) is an abbreviation for Secure Digital. CF is an abbreviation for CompactFlash (registered trademark). DVD is an abbreviation for Digital Versatile Disk. 
     The input interface  930  is a port to be connected with an input device, such as a mouse, a keyboard, or a touch panel. Specifically, the input interface  930  is a Universal Serial Bus (USB) terminal. The input interface  930  may be a port to be connected with a local area network (LAN). 
     The output interface  940  is a port to which a cable of a display device  941 , such as a display, is to be connected. Specifically, the output interface  940  is a USB terminal or a High Definition Multimedia Interface (HDMI, registered trademark) terminal. Specifically, the display is a liquid crystal display (LCD). 
     The communication device  950  has a receiver and a transmitter. Specifically, the communication device  950  is a communication chip or a network interface card (NIC). In this embodiment, the space traffic management devices  100  of the mega-constellation business device  41 , the space object business device  42 , and the collision avoidance assistance business device  43  communicate mutually via the secret communication line  200  that is kept secret with the common cryptographic key  521 . For communication that does not need to be kept secret, the communication is performed via an ordinary communication line. 
     The space traffic management program is read into the processor  910  and executed by the processor  910 . The memory  921  stores not only the space traffic management program but also an operating system (OS). The processor  910  executes the space traffic management program while executing 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 that are stored in the auxiliary storage device  922  are loaded into the memory  921  and executed by the processor  910 . Part or the entirety of the space traffic management program may be embedded in the OS. 
     The space traffic management device  100  may include a plurality of processors as an alternative to the processor  910 . These processors share the execution of programs. Each of the processors is, like the processor  910 , a device that executes programs. 
     Data, information, signal values, and variable values that are used, processed, or output by programs are stored in the memory  921  or the auxiliary storage device  922 , or stored in a register or a cache memory in the processor  910 . 
     “Unit” of each unit of the space traffic management device may be interpreted as “process”, “procedure”, “means”, “phase”, or “step”. “Process” of an orbit analysis process and a notification process may be interpreted as “program”, “program product”, or “computer readable recording medium recording a program”. The terms “process”, “procedure”, “means”, “phase”, and “step” may be interpreted interchangeably. The space traffic management program causes a computer to execute each process, each procedure, each means, each phase, or each step, where “unit” of each unit of the space traffic management system is interpreted as “process”, “procedure”, “means”, “phase”, or “step”. A space traffic management method is a method performed by execution of the space traffic management program by the space traffic management device  100 . 
     The space traffic management program may be stored and provided in a computer readable recording medium. Alternatively, each program may be provided as a program product. 
       FIG.  10    is a diagram illustrating an example of the orbit forecast information  51  according to this embodiment. 
     The space traffic management device  100  stores, in the storage unit  140 , the orbit forecast information  51  in which forecast values of orbits of space objects  60  are set. For example, the space traffic management device  100  may acquire forecast values of the orbit of each of the space objects  60  from the business device  40  used by a management business operator that manages the space objects  60  and store them as the orbit forecast information  51 . Alternatively, the space traffic management device  100  may acquire the orbit forecast information  51  in which forecast values of the orbit of each of the space objects  60  are set from the management business operator and store it in the storage unit  140 . 
     The management business operator is a business operator that manages the space objects  60  that fly in outer space, such as a satellite constellation, various types of satellites, a rocket, and debris. As described above, the business device  40  used by each management business operator is a computer, such as a mega-constellation business device, 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 an SSA business device. 
     The orbit forecast information  51  includes satellite orbit forecast information  52  and debris orbit forecast information  53 . In the satellite orbit forecast information  52 , forecast values of orbits of satellites are set. In the debris orbit forecast information  53 , forecast values of orbits of debris are set. In this embodiment, it is arranged that the satellite orbit forecast information  52  and the debris orbit forecast information  53  are included in the orbit forecast information  51 . However, the satellite orbit forecast information  52  and the debris orbit forecast information  53  may be stored in the storage unit  140  as separate pieces of information. 
     In the orbit forecast information  51 , information such as a space object identifier (ID)  511 , a forecast epoch  512 , forecast orbital elements  513 , and a forecast error  514  is set, for example. 
     The space object ID  511  is an identifier that identifies a space object  60 . In  FIG.  10   , a satellite ID and a debris ID are set as the space object ID  511 . Specifically, a space object is an object such as a rocket to be launched into outer space, an artificial satellite, a space station, a debris removal satellite, a planetary space probe, or a satellite or rocket that has become debris after completing a mission. 
     The forecast epoch  512  is an epoch that is forecast for the orbit of each of the space objects. 
     The forecast orbital elements  513  are orbital elements that identify the orbit of each of the space objects. The forecast orbital elements  513  are orbital elements that are forecast for the orbit of each of the space objects. In  FIG.  10   , the six Keplerian elements are set as the forecast orbital elements  513 . 
     The forecast error  514  is an error that is forecast for the orbit of each of the space objects. In the forecast error  514 , a traveling direction error, an orthogonal direction error, and a basis for the error are set. In this way, the forecast error  514  explicitly indicates the amount of error included in a record value together with the basis. The basis for the amount of error includes at least one or all of means for measurement, the content of data processing performed as means for improving the precision of location coordinate information, and a result of statistical evaluation on past data. 
     In the orbit forecast information  51  according to this embodiment, the forecast epoch  512  and the forecast orbital elements  513  are set for the space object  60 . Using the forecast epoch  512  and the forecast orbital elements  513 , the time and location coordinates of the space object  60  in the near future can be obtained. For example, the time and location coordinates of the space object  60  in the near future may be set in the orbit forecast information  51 . 
     The orbit forecast information  51  thus includes information on the orbit of each space object including the epoch and orbital elements or the time and location coordinates, and explicitly indicates forecast values of the space object  60  in the near future. 
     Referring to  FIGS.  11  and  12   , an example of a functional configuration of the space traffic management system  500  according to this embodiment will now be described. The hardware configuration of each of the space traffic management devices  100  is as described above. 
     The space traffic management devices  100  included in the space traffic management system  500  are mutually connected with the secret communication line  200  using the common cryptographic key  521 . The space traffic management devices  100  are provided respectively in the mega-constellation business device  41 , the space object business device  42 , and the collision avoidance assistance business device  43 . 
     Mega-Constellation Business Device  41   
     The space traffic management device  100  of the mega-constellation business device  41  includes a space information recorder  101 , a danger alert device  102 , a danger analysis device  103  to analyze the orbit of a space object, a danger avoidance action assistance device  104 , and danger avoidance action implementation plan information  105 . 
     The space information recorder  101  of the mega-constellation business device  41  records orbit information of satellites of a mega-constellation. A specific example of the space information recorder  101  is the orbit forecast information  51  of  FIG.  10   . The space information recorder  101  includes public orbit information  61  associated with a satellite group ID that identifies a satellite group and real-time high-precision orbit information  63  associated with satellite IDs that identify satellites. 
     The public orbit information  61  is orbit information that can be disclosed to other business devices. In the public orbit information  61 , information on constituent satellites, such as the number of satellites constituting the satellite group and satellite IDs, upper and lower limits of the orbital altitude of the satellite group, and upper and lower limits of the orbital inclination of the satellite group are set. 
     The real-time high-precision orbit information  63  is forecast orbit information and record orbit information of individual satellites of the satellite group. 
     The danger alert device  102  notifies a danger of proximity or collision with a space object. The danger alert device  102  includes orbit information associated with a space object ID that identifies a space object, and also has disclosure condition information in which a disclosure condition for the orbit information is set. 
     The danger analysis device  103  analyzes the orbit of a space object. For example, the danger analysis device  103  is an example of the collision analysis unit  411  that analyzes collisions between the specific space object S and individual satellites in a mega-constellation satellite group. 
     The danger avoidance action assistance device  104  plans responsibility assignment for an avoidance action for a space object. For example, the danger avoidance action assistance device  104  is an example of the countermeasure planning unit  412  that plans a collision avoidance countermeasure when a collision between the mega-constellation and the specific space object S is foreseen. 
     In the danger avoidance action implementation plan information  105 , an avoidance action plan created by the danger avoidance action assistance device  104  is set. 
       FIG.  12    is an example of the space information recorder of the mega-constellation business device  41  according to this embodiment  1 .  FIG.  12    describes, in particular, details of the real-time high-precision orbit information  63 . 
     In the real-time high-precision orbit information  63 , forecast orbit information and record orbit information are set in association with each satellite ID. The forecast orbit information and the record orbit information are set such that they are real-time and highly precise. 
     Space Object Business Device  42   
     The space traffic management device  100  of the space object business device  42  includes a space information recorder  101 . The space object business device  42  manages, for example, a satellite whose orbit information is not appropriate to be disclosed or whose orbit information is kept secret. Therefore, the space information recorder  101  of the space traffic management device  100  of the space object business device  42  includes non-public orbit information  62  associated with a space object ID that is the ID of the specific space object S. 
     In the non-public orbit information  62 , forecast orbit information of the space object S is set. In the forecast orbit information, an epoch, orbital elements, and a predicted error are set, as in  FIG.  10   . 
     Collision Avoidance Assistance Business Device  43   
     The space traffic management device  100  of the collision avoidance assistance business device  43  includes a space information recorder  101 , a danger alert device  102 , and a danger analysis device  103 . 
     The space information recorder  101  of the collision avoidance assistance business device  43  records the non-public orbit information  62  of the space object S that is received from the space object business device  42  via the secret communication line  200 . The non-public orbit information  62  of the space object S is associated with the space object ID that indicates the ID of the space object S. 
     The space information recorder  101  of the collision avoidance assistance business device  43  also records the public orbit information  61  that is received from the mega-constellation business device  41  and is associated with a satellite group ID. In the public orbit information  61 , orbit information or flight region information of a mega-constellation is set. 
     As described above, the database included in the space traffic management device  100  of the collision avoidance assistance business device  43  records the following information. 
     The non-public orbit information  62  of the specific space object S that is received from the space object business device  42  via the communication line that is kept secret. Orbit information or flight region information of a satellite group of a satellite constellation that is acquired from the mega-constellation business device  41 . 
     The danger analysis device  103  analyzes the orbit of a space object. The danger analysis device  103  is an example of the orbit analysis unit  431  that analyzes the orbit of the specific space object S. The danger analysis device  103  analyzes, for example, whether the specific space object S will intrude into an orbital altitude region where a satellite group of a satellite constellation flies. 
     The danger alert device  102  notifies danger of a proximity or collision with a space object. The danger alert device  102  is an example of the notification unit  432  that notifies a mega-constellation business operator of an intrusion alert and the non-public orbit information  62  of the specific space object S via the secret communication line  200  when it is foreseen that the specific space object S will intrude into an orbital altitude region where a satellite group of a satellite constellation flies. 
     DESCRIPTION OF OPERATION 
       FIG.  13    is a flowchart of a space traffic management process of the space traffic management system  500  according to this embodiment. The orbit analysis unit  431  and the notification unit  432  are provided in the server of the space traffic management device  100  of the collision avoidance assistance business device  43 . The collision analysis unit  411  and the countermeasure planning unit  412  are provided in 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 assistance business device  43  receives the non-public orbit information  62  of the specific space object S from the space object business device  42  via the secret communication line  200 . 
     The space traffic management device  100  of the collision avoidance assistance business device  43  also receives the public orbit information  61  in which orbit information or flight region information of a mega-constellation satellite group is set from the mega-constellation business device  41 . The public orbit information  61  may be communicated via the secret communication line  200 , or may be communicated via an ordinary communication line. The public orbit information  61  may be recorded in advance in the database of the space traffic management device  100  of the collision avoidance assistance business device  43 . 
     The database of the space traffic management device  100  of the collision avoidance assistance business device  43  records the non-public orbit information  62  of the specific space object S and the public orbit information  61  in which the orbit information or flight region information of the mega-constellation satellite group is set. 
     In step S 102 , the orbit analysis unit  431  analyzes the orbit of the specific space object S. Specifically, the orbit analysis unit  431  analyzes whether the specific space object S will intrude into an orbital altitude region where a satellite group of a satellite constellation flies. 
     In step S 103 , if it is foreseen that the specific space object S will intrude into the orbital altitude region where the mega-constellation satellite group flies, the process proceeds to step S 104 . 
     In step S 104 , the notification unit  432  notifies the mega-constellation business operator of an intrusion alert and the non-public orbit information  62  of the specific space object S via the secret communication line  200 . Although the intrusion alert may be notified via an ordinary communication line, the non-public orbit information  62  is notified via the secret communication line  200 . 
     In step S 105 , the collision analysis unit  411  analyzes collisions between the specific space object S and individual satellites in the mega-constellation satellite group. The collision analysis unit  411  analyzes collisions between the specific space object S and individual satellites in the mega-constellation satellite group, using the non-public orbit information  62  of the space object S and the information recorded in the space information recorder  101  of its own device. 
     In step S 106 , if a collision is foreseen, the process proceeds to step S 107 . 
     In step S 107 , the countermeasure planning unit  412  plans a collision avoidance countermeasure to avoid a collision between the specific space object S and a satellite in the satellite group of the satellite constellation. The collision avoidance countermeasure is set in the danger avoidance action implementation plan information  105  in the mega-constellation business device  41 . 
     OTHER CONFIGURATIONS 
     In this embodiment, the functions of the space traffic management device  100  are realized by software. As a variation, the functions of the space traffic management device  100  may be realized by hardware. 
     In  FIG.  14   , a hardware configuration of the space traffic management device  100  according to a variation of this embodiment will be described. The hardware configuration of the space traffic management device  100  will be described using the space traffic management device  100  of the mega-constellation business device  41  as an example. It is assumed that the space traffic management devices  100  of the other business devices  40  also have substantially the same hardware configuration. 
     As described above, the space traffic management device  100  of the mega-constellation business device  41  includes the collision analysis unit  411 , the countermeasure planning unit  412 , and the storage unit  140  as an example of functional elements that realize the mega-constellation management function. 
     The space traffic management device  100  includes an electronic circuit  909  in place of the processor  910 . 
     The electronic circuit  909  is a dedicated electronic circuit that realizes the functions of the space traffic management device  100 . 
     Specifically, the electronic circuit  909  is a single circuit, a composite circuit, a programmed processor, a parallel-programmed processor, a logic IC, a GA, an ASIC, or an FPGA. GA is an abbreviation for Gate Array. 
     The functions of the space traffic management device  100  may be realized by one electronic circuit, or may be distributed among and realized by a plurality of electronic circuits. 
     As another variation, some of the functions of the space traffic management device  100  may be realized by the electronic circuit, and the rest of the functions may be realized by software. 
     Each of the processor and the electronic circuit is also called processing circuitry. That is, the functions of the space traffic management device  100  are realized by the processing circuitry. 
     DESCRIPTION OF EFFECTS OF THIS EMBODIMENT 
       FIG.  15    is a diagram illustrating danger regions caused by a mega-constellation according to this embodiment. 
     In the space traffic management system according to this embodiment, orbit information of the space object S is used as non-public information, and is provided and received via the secret communication line. 
     Furthermore, the collision avoidance assistance business operator holds regions where mega-constellation satellite groups fly in the database in advance. Therefore, by analyzing the orbit of the space object S, the collision avoidance assistance business device can foresee an intrusion into a flight region of a mega-constellation satellite group. 
     The notification of an alert for this intrusion and the non-public orbit information of the space object S to the mega-constellation business operator concerned allows collision analysis to be performed in the mega-constellation business device that holds real-time high-precision orbit information of the mega-constellation satellite group. 
     There is an effect that when a collision is foreseen, the collision can be avoided by a collision avoidance action by the mega-constellation satellite group. 
     There is an effect that even in a case in which the system for issuing alerts is transferred to a private business operator, non-public satellite information can be managed as secret information to be disclosed only to parties concerned. 
     Embodiment 2 
     In this embodiment, differences from Embodiment 1 and additions to Embodiment 1 will be mainly described. 
     In this embodiment, components that have substantially the same functions as those in Embodiment 1 will be denoted by the same reference signs and description thereof will be omitted. 
     DESCRIPTION OF CONFIGURATIONS AND OPERATION 
       FIG.  16    is a diagram illustrating a configuration of a space traffic management system  500   a  according to this embodiment. 
       FIG.  17    is a diagram illustrating a detailed configuration of forecast orbit information  64  according to this embodiment. Referring to  FIGS.  16  and  17   , an example of a functional configuration of the space traffic management system  500   a  according to this embodiment will be described. The hardware configuration of each of the space traffic management devices  100  is as described above. 
       FIG.  16    differs from  FIG.  11    in that the space object business device  42  includes a danger alert device  102  and danger avoidance action implementation plan information  105 . 
     The mega-constellation business device  41  may be without the danger alert device  102 , the danger analysis device  103 , the danger avoidance action assistance device  104 , and the danger avoidance action implementation plan information  105 . The collision avoidance assistance business device  43  and the mega-constellation business device  41  share the forecast orbit information  64  for each satellite in addition to the public orbit information  61  for each satellite group. 
     The space traffic management devices  100  of the space object business device  42  and the collision avoidance assistance business device  43  are connected with the secret communication line  200  that is kept secret with the common cryptographic key  521 . 
     The database of the space traffic management device  100  of the collision avoidance assistance business device  43  records the non-public orbit information  62  of the specific space object S that is received from the space object business device  42  via the secret communication line  200 . In addition, the database of the space traffic management device  100  of the collision avoidance assistance business device  43  records the orbit information or flight region information of the mega-constellation satellite group that is acquired from the mega-constellation business device  41 . 
     The server of the space traffic management device  100  of the collision avoidance assistance business device  43  includes the following phases. 
     The server of the collision avoidance assistance business device  43  analyzes the orbit of the specific space object S. 
     When it is foreseen that the specific space object S will intrude into the orbital altitude region where the mega-constellation satellite group flies, the server of the collision avoidance assistance business device  43  determines at least one representative satellite  311  from the mega-constellation satellite group that flies at the same orbital altitude. Then, the server acquires quasi-real-time high-precision orbit information  641 , which is predicted values of the orbit of the representative satellite  311 , and orbit information relative values  642  of constituent satellites  321  other than the representative satellite  311 . The orbit information relative values  642  of the constituent satellites  321  are values relative to the quasi-real-time high-precision orbit information  641  of the representative satellite  311 . 
     The server of the collision avoidance assistance business device  43  analyzes collisions between the specific space object S and individual satellites in the mega-constellation satellite group. 
     By the above phases, the forecast orbit information  64  for each satellite ID is recorded in the space information recorder  101  of the space traffic management device  100  of the collision avoidance assistance business device  43 . 
     Referring to  FIG.  17   , the forecast orbit information  64  according to this embodiment will be described. 
     The forecast orbit information  64  includes the quasi-real-time high-precision orbit information  641  of the representative satellites  311  and the orbit information relative values  642  of the constituent satellites  321 . 
     In the quasi-real-time high-precision orbit information  641  of the representative satellites  311 , an epoch, orbital elements, a predicted error, an information provider business device ID, and an information update date are set for each satellite ID. 
     In the orbit information relative values  642  of the constituent satellites  321 , a reference representative satellite ID, an orbital plane relative azimuth angle, an orbital plane relative azimuth angle, a relative elevation angle within an orbital plane, and a relative elevation angle between orbital planes are set for each satellite ID. 
     As illustrated in  FIG.  16   , the public orbit information  61  for each satellite group and the forecast orbit information  64  for each satellite are shared by the collision avoidance assistance business device  43  and the mega-constellation business device  41 . 
     The server of the space traffic management device  100  of the space object business device  42  has a phase of creating a collision avoidance action plan when a collision is foreseen. 
     Specifically, when a collision between the space object S and an individual satellite in the mega-constellation satellite group is foreseen by the collision avoidance assistance business device  43 , a notification is issued from the danger alert device  102  of the collision avoidance assistance business device  43  to the danger alert device  102  of the space object business device  42 . Based on this notification, the server of the space object business device  42  generates danger avoidance action implementation plan information  105 . 
     DESCRIPTION OF EFFECTS OF THIS EMBODIMENT 
     In the space traffic management system  500   a  according to this embodiment, an avoidance action may be carried out as appropriate at the discretion of a mega-constellation business operator. 
     With the space traffic management system  500   a  according to this embodiment, there is an effect that collision analysis and an collision avoidance action can be carried out by providing secret information only to a space object business operator and a collision avoidance assistance business operator. 
     Embodiment 3 
     In this embodiment, differences from Embodiments 1 and 2 and additions to Embodiments 1 and 2 will be mainly described. 
     In this embodiment, components that have substantially the same functions as those in Embodiments 1 and 2 will be denoted by the same reference signs and description thereof will be omitted. 
     DESCRIPTION OF CONFIGURATIONS AND OPERATION 
       FIG.  18    is a diagram illustrating a configuration of a space traffic management system  500   b  according to this embodiment. 
     Referring to  FIG.  18   , an example of a functional configuration of the space traffic management system  500   b  according to this embodiment will be described. The hardware configuration of each of the space traffic management devices  100  is as described above. 
     In  FIG.  18   , the collision avoidance assistance business device  43  and the mega-constellation business device  41  share the forecast orbit information  64  for each satellite in addition to the public orbit information  61  for each satellite group. 
     The space traffic management system  500   b  connects the space traffic management devices  100  installed respectively in the space object business device  42 , the collision avoidance assistance business device  43 , and the mega-constellation business device  41  with the secret communication line  200 . 
     The database of the space traffic management device  100  of the collision avoidance assistance business device  43  records the non-public orbit information  62  of the specific space object S that is received from the space object business device  42  via the secret communication line  200 . In addition, the database of the space traffic management device  100  of the collision avoidance assistance business device  43  records orbit information or flight region information of a mega-constellation satellite group acquired from the mega-constellation business device  41 . 
     The server of the space traffic management device  100  of the collision avoidance assistance business device  43  has the following phases. 
     The server of the collision avoidance assistance business device  43  analyzes the orbit of a specific space object. 
     When it is foreseen that the specific space object S will intrude into the orbital altitude region where the mega-constellation satellite group flies, the server of the collision avoidance assistance business device  43  determines at least one representative satellite  311  from the mega-constellation satellite group that flies at the same orbital altitude. Then, the server acquires the quasi-real-time high-precision orbit information  641 , which is predicted values of the orbit of the representative satellite  311 , and orbit information relative values  642  of constituent satellites  321  other than the representative satellite  311 . The orbit information relative values  642  of the constituent satellites  321  are values relative to the quasi-real-time high-precision orbit information  641  of the representative satellite  311 . As illustrated in  FIG.  18   , the public orbit information  61  for each satellite group and the forecast orbit information  64  for each satellite are shared by the collision avoidance assistance business device  43  and the mega-constellation business device  41 . The configuration of the forecast orbit information  64  is substantially the same as that described in  FIG.  17   . 
     The server of the collision avoidance assistance business device  43  analyzes collisions between the specific space object S and individual satellites in the mega-constellation satellite group. 
     When a collision is foreseen, the server of the collision avoidance assistance business device  43  notifies the mega-constellation business operator of a collision alert and the non-public orbit information  62  of the specific space object S via the secret communication line  200 , 
     The server included in the space traffic management device  100  of the mega-constellation business device  41  has a phase of planning a collision avoidance countermeasure. Specifically, the mega-constellation business device  41  generates danger avoidance action implementation plan information  105 . 
     DESCRIPTION OF EFFECTS OF THIS EMBODIMENT 
     In the space traffic management system  500   b  according this embodiment, when a collision avoidance action is to be carried out on the mega-constellation side, the collision avoidance assistance business device  43  needs to share secret information with the mega-constellation business operator only when a collision alert has been issued. Therefore, with the space traffic management system  500   b  according to this embodiment, there is an effect that information disclosure occasions can be limited to the minimum. 
     In Embodiments 1 to 3 above, business devices such as the following have been described. 
     A satellite constellation business device is included in a space traffic management system. The satellite constellation business device includes a collision analysis unit to analyze a collision between a specific space object and an individual satellite in a satellite group of a satellite constellation and a countermeasure planning unit to plan a collision avoidance countermeasure when a collision is foreseen. 
     A mega-constellation business device is included in the space traffic management system. The mega-constellation business device includes a collision analysis unit to analyze a collision between a specific space object and an individual satellite in a mega-constellation satellite group and a countermeasure planning unit to plan a collision avoidance countermeasure when a collision is foreseen. 
     The mega-constellation business device included in the space traffic management system plans a collision avoidance countermeasure. 
     A space object business device included in the space traffic management system creates a collision avoidance action plan. 
     An SSA business device (space situational awareness business device) that conducts an SSA business also functions as the collision avoidance assistance business device. 
     The space object business device also functions as the collision avoidance assistance business device. 
     Embodiment 4 
     In this embodiment, differences from Embodiments 1 to 3 and additions to Embodiments 1 to 3 will be mainly described. 
     In this embodiment, components that have substantially the same functions as those in Embodiments 1 to 3 will be denoted by the same reference signs and description thereof will be omitted. 
     The emergence of mega-constellation business operators has caused a situation where several thousand satellites are flying all over the sky at orbital altitudes of 500 km and lower. As a result, there is a high risk that a satellite or the like that contributes to security will collide with a mega-constellation satellite. There may be cases in which orbit information cannot be disclosed, so that collision analysis or alert issuance by an SSA business operator or the like cannot be performed. Thus, Embodiments 1 to 3 have described arrangements for realizing a space traffic management system in which a collision avoidance assistance business operator and a mega-constellation business operator that share a cryptographic key are connected with a secret communication line, and a collision with a mega-constellation satellite group is analyzed based on non-public orbit information. 
     Consideration is being given to construction of a public information system called an open architecture data repository (OADR) so as to share information among business operators and secure fight safety for space objects. 
     In this embodiment, an arrangement in which flight safety of space objects is secured by a public information system called an OADR will be described. 
     When the OADR is constructed as a public institution for international cooperation, an authority for issuing an instruction or a request across a national border may be given to a business operator. 
     For example, to centrally manage orbit information of space objects held by business operators around the world, it is rational if an instruction or request to provide orbit information to the OADR can be made under rules based on an international consensus. 
     When a particular country constructs the OADR as a public institution, an authority to issue an instruction or request may be given to a business operator in the country concerned. 
     It may be arranged such that information is disclosed unconditionally to business operators of the country concerned and information is disclosed conditionally to other business operators. 
     As disclosure conditions, a payment requirement, a fee setting, a restriction of disclosed items, a restriction of precision of disclosed information, a restriction of disclosure frequency, non-disclosure to a specific business operator, and so on may be set. 
     For example, a difference between free and chargeable or a difference in fee for acquiring information may arise between the country concerned and other countries, and the setting of disclosure conditions by the OADR will have influence in creating a system of space traffic management or in terms of industrial competitiveness. 
     It is rational that confidential information on space objects that contributes to security is held by the OADR constructed as a public institution by a nation and is not disclosed to third parties. For this reason, the OADR may include a database to store non-public information in addition to a database for the purpose of information disclosure. 
     Space object information held by a private business operator includes information that cannot be disclosed generally due to corporate secrets or the like. There is also information that is not appropriate to be disclosed generally because of a huge amount of information or a high update frequency due to constant maneuver control. 
     When danger analysis and analytical evaluation related to proximities or collisions between space objects are to be performed, it is necessary to take into account orbit information of all space objects regardless of whether or not space objects require confidentiality. For this reason, it is rational that the OADR as a public institution carries out danger analysis taking confidential information into account, and discloses information conditionally by restricting a disclosure recipient or disclosure content if danger is foreseen as a result of analytical evaluation. For example, it is rational to process information to allow disclosure and then disclose the information by restricting a disclosure recipient or disclosure content, such as disclosing only orbit information of a time period with danger to a disclosure recipient that will contribute to avoiding the danger. 
     If the number of objects in orbit increases and the risk of proximity or collision increases in the future, various danger avoidance measures will be necessary, such as means by which a debris removal business operator removes dangerous debris or means by which a mega-constellation business operator changes an orbital location or passage timing to avoid a collision. If the OADR that is a public institution can instruct or request a business operator to execute a danger avoidance action, a significant effect can be expected in securing flight safety in space. 
     There are space objects that are managed by an institution such as a venture business operator in an emerging country or a university that has little experience in space business and lacks information that contributes to danger avoidance. If it is foreseen that a space object managed by such an institution that has little experience in space business and lacks information that contributes to danger avoidance will intrude into an orbital altitude zone in which a mega-constellation flies, danger avoidance can be effected promptly and effectively by the OADR acting as an intermediary to transmit information to business operators as required. 
     In addition, by executing a danger avoidance measure or by interceding for or introducing space insurance for private business operators, contribution can be made to the promotion and industrialization of space traffic management. 
     Arrangements for realizing the OADR include the following arrangements.
     An arrangement that includes only a public database.   An arrangement that has danger analysis means, collision avoidance assistance means, or space situational awareness (SSA) means, and independently contributes to danger avoidance.   An arrangement that makes an instruction or request to a business operator or performs intercession or introduction for a business operator, and contributes to danger avoidance by information management.   

     As arrangements for realizing the OADR, there are also various possibilities other than the above arrangements. 
     Note that “the OADR intercedes for implementation of a space traffic management method” means, for example, a case in which the entities that implement the space traffic management method are external business devices other than the OADR, and the OADR mediates between the business devices to prompt the implementation instead of forcibly ordering it. That “the OADR intercedes for implementation of the space traffic management method” is rephrased, for example, as “the OADR mediates so that external business devices other than the OADR cooperatively implement the space traffic management method”. Alternatively, “mediates” may be replaced with “provides direction”. 
     Configuration examples of the OADR according to this embodiment will be described below. 
     Configuration Example 1 of the OADR 
       FIG.  19    is Configuration Example  1  of an OADR  800  according to this embodiment. 
     The OADR  800  is a public information system that discloses orbit information of a space object. The OADR  800  includes a database  810  to store orbit information of space objects and a server  820 . 
     The database  810  includes a first database  811  to store pubic 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 at least one of a space traffic management device, an SSA business device (space situational awareness business device), a collision avoidance assistance business device, a mega-constellation business device, and a debris removal business device, and stores the space object information in the second database  812 . The space traffic management device is provided in the CSpOC, for example. 
     The CSpOC of the United States has not so far been equipped with a bidirectional line and has unidirectionally notified danger alerts. If the CSpOC is equipped with a space traffic management device, the space traffic management device allows contribution to be made to space traffic management through a bidirectional communication line with other business devices. 
     The server  820  generates conditional public information for which a disclosure recipient and disclosure content are restricted and stores the conditional public information in the first database  811 . 
     The server  820  transmits the conditional public information to only a specific business device among the SSA business device, the collision avoidance assistance business device, the mega-constellation business device, the debris removal business device, and a space insurance business device that handles space insurance. 
     The OADR  800  of Configuration Example 1 realizes the above-described functions and also intercedes for implementation of the space traffic management method described in Embodiments 1 to 3. 
     Confidential information on space objects that is held by the CSpOC and contributes to security may be disclosed only to the OADR. A proximity or collision risk needs to be analyzed and foreseen by taking confidential information into account. 
     Confidential information is processed into information that can be disclosed conditionally and then conditional public information that contributes to collision avoidance assistance is shared with only a business device involved in a collision risk. This allows even a private business operator to carry out a collision avoidance action. 
     In addition, with regard to space object information held by private business operators, if the OADR similarly processes space object information that cannot be generally disclosed into information that can be disclosed conditionally, collision avoidance becomes possible. 
     Configuration Example 2 of the OADR 
       FIG.  20    is Configuration Example 2 of the OADR  800  according to this embodiment. 
     Configuration Example 2 of the OADR  800  includes the collision avoidance assistance business device described in Embodiments 1 to 3 in addition to Configuration Example 1. As illustrated in  FIG.  20   , the server  820  may be configured to include the functions of the collision avoidance assistance business device. 
     The server  820  acquires space object information including non-public information from all or at least one of a space traffic management device, an SSA business device, a different collision avoidance assistance business device, a mega-constellation business device, a debris removal business device, and a space object business device, and stores the space object information in the second database  812 . The space traffic management device is installed in the CSpOC, for example. 
     Note that the different collision avoidance assistance business device is a collision avoidance assistance business device other than the collision avoidance assistance business device included in the OADR  800 . 
     The server  820  generates conditional public information for which a disclosure recipient and disclosure content are restricted and stores the conditional public information in the first database  811 . 
     The server  820  transmits the conditional public information only to a specific business device among the SSA business device, the different collision avoidance assistance business device, the mega-constellation business device, the debris removal business device, the space object business device, and a space insurance business device that handles space insurance. 
     By arranging that the OADR functions as a collision avoidance assistance business operator as in Configuration Example 2, similar effects as those of Configuration Example 1 can be obtained. 
     In Embodiments 1 to 4 above, each unit of the space traffic management system and the space traffic management device has been described as an independent functional block. However, the configurations of the space traffic management system and the space traffic management device may be different from the configurations described in the above embodiments. The functional blocks of the space traffic management system and the space traffic management device may be arranged in any configuration, provided that the functions described in the above embodiments can be realized. Each of the space traffic management system and the space traffic management device may be a single device or a system composed of a plurality of devices. 
     Portions of Embodiments 1 to 4 may be implemented in combination. Alternatively, one portion of these embodiments may be implemented. These embodiments may be implemented as a whole or partially in any combination. 
     That is, in Embodiments 1 to 4, portions of Embodiments 1 to 4 may be freely combined, or any constituent element may be modified. Alternatively, in Embodiments 1 to 4, any constituent element may be omitted. 
     The embodiments described above are essentially preferable examples and are not intended to limit the scope of the present disclosure, the scope of applications of the present disclosure, and the scope of uses of the present disclosure. The embodiments described above can be modified in various ways as necessary. 
     REFERENCE SIGNS LIST 
       20 : satellite constellation;  21 : orbital plane;  30 : satellite;  311 : representative satellite;  321 : constituent 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 planning unit;  431 : orbit analysis unit;  432 : notification unit;  42 : space object business device;  43 : collision avoidance assistance business device;  51 : orbit forecast information;  52 : satellite orbit forecast information; 
       53 : debris orbit forecast information;  511 : space object ID;  512 : forecast epoch;  513 : forecast orbital elements;  514 : forecast error;  521 : cryptographic key;  60 : space object;  70 : Earth;  100 : space traffic management device;  140 : storage unit;  55 : orbit control command;  61 : public orbit information;  62 : non-public orbit information;  63 : real-time high-precision orbit information;  64 : forecast orbit information;  641 : quasi-real-time high-precision orbit information;  642 : orbit information relative value;  500 ,  500   a,    500   b : 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 device;  950 : communication device;  101 : space information recorder;  102 : danger alert device;  103 : danger analysis device;  104 : danger avoidance action assistance device;  105 : danger avoidance action implementation plan information;  200 : secret communication line;  800 : OADR;  810 : database;  811 : first database;  812 : second database;  820 : server.