Patent Publication Number: US-2023143237-A1

Title: Space information recorder, danger analysis system, danger analysis method, mega-constellation business device, ssa business device, rocket launch business device, satellite business device, debris removal business device, orbital transfer business device, and oadr

Description:
TECHNICAL FIELD 
     The present disclosure relates to a space information recorder, a danger analysis system, a danger analysis method, a mega-constellation business device, an SSA business device, a rocket launch business device, a satellite business device, a debris removal business device, an orbital transfer 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. 
     CITATION LIST 
     Patent Literature 
     Patent Literature 1: JP 2017-114159 A 
     SUMMARY OF INVENTION 
     Technical Problem 
     With an increase in debris in outer space, an increase in the number of satellites due to the emergence of mega-constellations, and improvement in ground surveillance capability, it is becoming difficult to continue the existing alert issuance service by the CSpOC in the United States. Space situation awareness (SSA) is required to judge whether a space object will intrude into a satellite constellation. 
     In addition, there are management business operators that manage various space objects flying in space. These management business operators need to cooperate to analyze a proximity or collision between space objects. 
     However, Patent Literature 1 does not describe a system in which management business operators perform collision or proximity analysis while sharing orbit information of space objects. 
     An object of the present disclosure is to provide a system in which a satellite constellation business device that manages a satellite constellation performs proximity or collision danger analysis while sharing orbit information with management business devices. 
     Solution to Problem 
     A space information recorder according to the present disclosure acquires orbit forecast information from a management business device that is used by a management business operator that manages a plurality of space objects flying in space, and records the orbit forecast information, the orbit forecast information is forecast values of orbits of the plurality of space objects, and the space information recorder includes 
     two or more categories of 
     a category, acquired from a mega-constellation business device, of different constellations formed at nearby altitudes by a same business operator, the mega-constellation business device being a management business device of a satellite group constituting a mega-constellation composed of 100 or more satellites; 
     a category of a satellite group of each constellation that flies at a same nominal altitude and cooperatively realizes a same mission; 
     a category of orbital planes; 
     a category of each orbital plane of the orbital planes; and 
     a category of an individual satellite, 
     wherein the space information recorder includes information on upper and lower limit values of an orbital altitude or on a nominal altitude and an altitude fluctuation width for each category. 
     Advantageous Effects of Invention 
     With a space information recorder according to the present disclosure, there is an effect that a satellite constellation business device that manages a satellite constellation can perform proximity or collision danger analysis while sharing orbit information with management business devices. 
    
    
     
       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 configuration of a management business device other than a mega-constellation business device in a danger analysis system according to Embodiment 1; 
         FIG.  10    is an example of a configuration of the mega-constellation business device in the danger analysis system according to Embodiment 1; 
         FIG.  11    is an example of orbit forecast information included in a space information recorder according to Embodiment 1; 
         FIG.  12    is a diagram illustrating fluctuations in orbital altitude in a category of an individual satellite in a steady operation phase in a satellite constellation; 
         FIG.  13    is a diagram illustrating variations in orbital plane shape in a category of the same orbital plane in a constellation satellite group that realizes a single mission at the same altitude (nominal); 
         FIG.  14    is a diagram illustrating relative fluctuations between satellites in the same orbital plane (synchronous operation in steady operation); 
         FIG.  15    is a diagram illustrating factors in fluctuations in multiple orbital planes in a constellation satellite group that realizes a single mission at the same altitude (nominal); 
         FIG.  16    is a diagram illustrating a change of altitudes in a category of a constellation satellite group; 
         FIG.  17    is a diagram illustrating an example of a category of different constellation satellite groups of the same business operator at nearby altitudes; 
         FIG.  18    is an example of a configuration and a usage pattern of orbital altitude information for each category included in the space information recorder according to Embodiment 1; 
         FIG.  19    is an example of a configuration and a usage pattern of orbital altitude information for each category included in the space information recorder according to Embodiment 1; 
         FIG.  20    is an example of a configuration and a usage pattern of orbital altitude information for each category included in the space information recorder according to Embodiment 1; 
         FIG.  21    is an example of a configuration and a usage pattern of orbital altitude information for each category included in the space information recorder according to Embodiment 1; 
         FIG.  22    is a diagram illustrating an example of issuance of alerts when debris passes through orbital altitudes of a satellite constellation according to Embodiment 1; 
         FIG.  23    is a flowchart of an intrusion alert process according to Embodiment 1; 
         FIG.  24    is an example of a configuration of the management business device other than the mega-constellation business device in the danger analysis system according to a modification example of Embodiment 1; 
         FIG.  25    is an example of a configuration of the mega-constellation business device in the danger analysis system according to a modification example of Embodiment 1; and 
         FIG.  26    is a diagram illustrating an example of a functional configuration of an OADR according to Embodiment 2. 
     
    
    
     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 information recorder 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 composed of 100 or more satellite 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. 
     Due to the increase in debris in outer space, a dramatic increase in the total number of objects in outer space due to the emergence of mega-constellation business operators, and a dramatic increase in the amount of information due to the improvement in surveillance capability for objects in orbit, it is difficult for a single business operator to perform proximity and collision analysis for space objects. 
     Satellites in steady operation control the orbit and attitude moment to moment. For this reason, in order to grasp orbit information with high precision, it is necessary to update information moment to moment. In particular, it is increasingly difficult to share quasi-real time information of a satellite group of several thousand satellites of a mega-constellation business operator among many business operators. 
     On the other hand, danger risks such as proximities and collisions between space objects are increasing. 
     Under such circumstances, it is hoped that a rational system will be created in which proximity and collision analysis including a mega-constellation satellite group is performed, and if danger is foreseen, detailed analysis can be performed. 
     In a mega-constellation composed of polar orbit satellites, there are congested regions in the polar regions and there is a collision risk within the system. In a mega-constellation composed of inclined orbit satellites, there are many intersections of orbital planes over the entire mid-latitude zone, so that there is a collision risk within the system. In order to eliminate this collision risk, it is effective to change the orbital altitude between orbital planes with different normal vectors. This is because space objects between which there is no intersection of orbits will not collide with each other. 
     When this collision avoidance measure is adopted, variations in the actual orbital altitude of the satellite group with respect to the nominal orbital altitude are large, so that proximity and collision analysis using only nominal orbital altitude information is insufficient. Means for providing and receiving orbit information that appropriately reflects differences in orbital altitude is indispensable. 
     In this embodiment, high-precision orbit information of individual satellites that is used for collision analysis by a mega-constellation business operator and orbit information that is used by other business operators are classified by category. A space information recorder that lists the upper and lower limit values for each category, focusing on orbital altitudes, is provided. 
     By selecting a category with an amount of information and precision that are appropriate for each purpose of a business operator, it is possible to rationally perform both proximity and collision analysis with coarse precision on a macro level and collision analysis with high precision when a collision is foreseen demonstrably. 
     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. 
     The satellite constellation forming system  600  is installed in a management business device  40  operated by a management business operator that manages a satellite constellation, such as a mega-constellation business device  41 , an LEO constellation business device  42 , or a satellite business device  43 . LEO is an abbreviation for Low Earth Orbit. 
     A satellite control scheme by the satellite constellation forming system  600  is also applied to the management business device  40  that controls a satellite. Specifically, it may be installed on the management business device  40  such as a debris removal business device  45  that manages a debris removal satellite, a rocket launch business device  46  that launches a rocket, and an orbital transfer business device  44  that manages an orbital transfer satellite. 
     The satellite control scheme by the satellite constellation forming system  600  may be installed in any management business device, provided that it is a management business device of a business operator that manages a space object  60 . 
     Each device of the management business device  40  will be described later. 
       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 the ground facility  700  to be described later with reference to  FIG.  8   . 
     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 an apogee kick motor, a chemical propulsion device, or an electronic propulsion device. The apogee kick motor (AKM) is an upper-stage propulsion device used for orbital insertion of an artificial satellite, and is also called an apogee motor (when a solid rocket motor is used) or an apogee engine (when a liquid engine is used). 
     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 apogee kick motor is the name of a device used for orbital transfer and may be one type of chemical propulsion device. 
     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  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  will be described later with reference to  FIG.  8   . 
     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 . 
     The ground facility  700  includes the processor  910  and also includes other hardware components 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 with other hardware components via signal lines and controls these other hardware components. 
     The processor  910  is a device that executes programs. The programs are those that realize the functions of the ground facility  700 . In  FIG.  8   , the program that realizes the functions of the ground facility  700  is a satellite constellation forming program to form a satellite constellation. 
     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). 
     The programs are read into the processor  910  and executed by the processor  910 . The memory  921  stores not only the programs but also an operating system (OS). The processor  910  executes the programs while executing the OS. The programs and the OS may be stored in the auxiliary storage device  922 . The programs 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 each program may be embedded in the OS. 
     The ground facility  700  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 ground facility  700  may be interpreted as “process”, “procedure”, “means”, “phase”, or “step”. “Process” where “unit” of each unit is interpreted as “process” may be interpreted as “program”, “program product”, “computer readable recording medium recording a program”, or “computer readable storage medium storing a program”. The terms “process”, “procedure”, “means”, “phase”, and “step” can be interpreted interchangeably. 
     Each program causes a computer to execute each process, each procedure, each means, each phase, or each step, where “unit” of each unit of the ground facility  700  is interpreted as “process”, “procedure”, “means”, “phase”, or “step”. 
     Each program may be stored and provided in a computer readable recording medium. Alternatively, each program may be provided as a program product. 
     DESCRIPTION OF CONFIGURATIONS 
       FIG.  9    is an example of a configuration of the management business device  40  in a danger analysis system  500  according to this embodiment.  FIG.  9    illustrates an example of the configuration of the management business device  40  other than the mega-constellation business device  41 . 
       FIG.  10    is an example of a configuration of the mega-constellation business device  41  in the danger analysis system  500  according to this embodiment. 
     The danger analysis system  500  includes a space information recorder  100  and the management business device  40 . The danger analysis system  500  is a system that foresees in advance a collision risk between two space objects among a plurality of space objects so as to avoid a collision. 
     The space information recorder  100  acquires orbit forecast information, which is forecast values of orbits of space objects, from the management business device  40  that is used by a management business operator that manages space objects flying in space, and records the orbit forecast information. The space information recorder  100  may be installed in the management business device  40 , or may be installed in another device that communicates with each management business device  40 . The space information recorder  100  may be installed in the ground facility  700 . Alternatively, the space information recorder  100  may be installed in the satellite constellation forming system  600 . 
     The management business device  40  provides information related to space objects  60  such as artificial satellites or debris. The management business device  40  is a computer of a business operator that collects information related to the space objects  60  such as artificial satellites or debris. 
     The management business device  40  includes devices such as the mega-constellation business device  41 , the LEO constellation business device  42 , the satellite business device  43 , the orbital transfer business device  44 , the debris removal business device  45 , the rocket launch business device  46 , and an SSA business device  47 . 
     The mega-constellation business device  41  manages a mega-constellation composed of 100 or more satellites. The mega-constellation business device  41  is a computer of a mega-constellation business operator that conducts a large-scale constellation, that is, mega-constellation business. 
     The LEO constellation business device  42  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  43  is a computer of a satellite business operator that handles one to several satellites. 
     The orbital transfer business device  44  is a computer of an orbital transfer business operator that performs a space object intrusion alert for a satellite. 
     The debris removal business device  45  is a computer of a debris removal business operator that conducts a debris retrieval business. 
     The rocket launch business device  46  is a computer of a rocket launch business operator that conducts a rocket launch business. 
     The SSA business device  47  is a computer of an SSA business operator that conducts an SSA business, that is, a space situational awareness business. 
     The management business device  40  may be a device other than the above, provided that it is the device that collects information on space objects such as artificial satellites or debris, and provides the collected information to the space information recorder  100 . When the space information recorder  100  is installed on an SSA public server, the space information recorder  100  may be configured to function as the SSA public server. 
     The information provided from the management business device  40  to the space information recorder  100  will be described in detail later. 
     The management business device  40  of  FIG.  9    includes a processor  910  and also includes other hardware components such as a memory  921 , an auxiliary storage device  922 , and a communication device  950 . 
     The management business device  40  of  FIG.  9    includes, as functional elements, a determination unit  110 , an issuance unit  120 , and a storage unit  140 . In the storage unit  140 , the space information recorder  100  is stored. 
     The functions of the determination unit  110  and the issuance unit  120  are realized by software or hardware. 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 . 
     As illustrated in  FIG.  10   , the mega-constellation business device  41  includes a processor  910  and also includes other hardware components such as a memory  921 , an auxiliary storage device  922 , and a communication device  950 . 
     The mega-constellation business device  41  of  FIG.  10    includes, as functional elements, a danger analysis unit  410  and a storage unit  140 . In the storage unit  140 , the space information recorder  100  is recorded. 
     The functions of the danger analysis unit  410  are realized by software or hardware. 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.  11    is a diagram illustrating an example of orbit forecast information  51  included in the space information recorder  100  according to this embodiment. 
     The space information recorder  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 information recorder  100  may acquire forecast values of the orbit of each of space objects  60  from the management 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 information recorder  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 space objects  60  that fly in space, such as a satellite constellation, various types of satellites, a rocket, and debris. As described above, the management business device  40  used by each management business operator is a computer such as the mega-constellation business device  41 , the LEO constellation business device  42 , the satellite business device  43 , the orbital transfer business device  44 , the debris removal business device  45 , the rocket launch business device  46 , or the SSA business device  47 . 
     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 the orbits of satellites are set. In the debris orbit forecast information  53 , forecast values of the 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. 
     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 . Specifically, a space object is an object such as a rocket 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.  11   , 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 travelling 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. The time and location coordinates of the space object  60  in the near future may be set in the orbit forecast information  51 . 
     As described above, the orbit forecast information  51  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. 
     With respect to satellite constellations of mega-constellation business operators, factors in variations and fluctuations in orbital altitude are analyzed and classified as described below, focusing on each of a category of an individual satellite, a category of the same orbital plane, a category of multiple orbital planes, a category of constellations with the same nominal altitude, and constellations at nearby orbital altitudes. 
       FIG.  12    is a diagram illustrating fluctuations in orbital altitude in a category of an individual satellite in a steady operation phase in a satellite constellation. 
     The factors in fluctuations in orbital altitude in the category of an individual satellite in a steady operation phase in a satellite constellation according to this embodiment include the following factors. 
     &lt;&lt;Deviations in Shape of One Orbit&gt;&gt; 
     
         
         Fluctuations due to a flattening effect of Earth 
         Fluctuations due to gravity deviations of Earth 
         Deviations due to eccentricity 
       
    
     &lt;&lt;Deviations in Altitude of One Orbit&gt;&gt; 
     
         
         Above the polar region/above the equator 
         Perigee/apogee
 
&lt;&lt;Fluctuations Over time&gt;&gt;
 
         Daily fluctuations 
         Seasonal fluctuations 
       
    
     &lt;&lt;Fluctuations Due to Orbit or Attitude Control&gt;&gt; 
     
         
         Altitude rise due to acceleration 
         Altitude drop due to deceleration 
         Fluctuations due to changes in orbital inclination 
       
    
     &lt;&lt;Altitude Drop Due to Deceleration Caused by Atmospheric Drag&gt;&gt; 
     &lt;&lt;Tolerances and Errors&gt;&gt; 
     
         
         Difference between a planned orbit by design and an actual orbit 
         Difference between analytical prediction and an actual orbit 
       
    
       FIG.  13    is a diagram illustrating variations in the shape of the orbital plane in a category of the same orbital plane in a constellation satellite group that realizes a single mission at the same altitude (nominal). 
     The factors in fluctuations in the category of the same orbital plane in a constellation satellite group that realizes a single mission at the same altitude (nominal) include the following factors. 
     &lt;&lt;Variations in the Shape of Orbital Plane&gt;&gt; 
     
         
         Difference in eccentricity between satellites 
         Difference in major axis vector between satellites 
       
    
       FIG.  14    is a diagram illustrating relative fluctuations between satellites in the same orbital plane (synchronous operation in steady operation). 
     The relative fluctuations between satellites in the same orbital plane (synchronous operation in steady operation) include the following factors. 
     &lt;&lt;Relative Fluctuations Between Satellites in the Same Orbital Plane (Synchronous Operation in Steady Operation)&gt;&gt; 
     
         
         Influence of orbit or attitude control for relative altitude or position adjustment 
         Effect of acceleration or deceleration for relative position adjustment 
       
    
       FIG.  15    is a diagram illustrating factors in fluctuations in a category of multiple orbital planes in a constellation satellite group that realizes a single mission at the same altitude (nominal). 
     The factors in fluctuations in the category of multiple orbital planes in a constellation satellite group that realizes a single mission at the same altitude (nominal) include the following factors. 
     &lt;&lt;Factors in Fluctuations in the Category of Multiple Orbital Planes in a Constellation Satellite Group that Realizes a Single Mission at the Same Altitude (Nominal)&gt;&gt;
     Upper and lower limits when the orbital altitude is changed for each orbital plane for collision avoidance   Upper and lower limits when the eccentricity is changed for each orbital plane   Upper and lower limits when the major axis vector is changed for each orbital plane   

       FIG.  16    is a diagram illustrating changes of altitudes in a category of a constellation satellite group. 
     The category of changes of altitudes of a constellation satellite group include the following factors. 
     &lt;&lt;Category of Changes of Altitudes of a Constellation Satellite Group&gt;&gt; 
     
         
         Altitude rise or drop of the entire satellite group for a collision avoidance action 
         Altitude information or drop of part of the satellite group for a collision avoidance action 
       
    
       FIG.  17    is a diagram illustrating an example of a category of constellation satellite groups of the same business operator at nearby altitudes. 
     As a specific example, a mega-constellation business operator in the United States has announced plans to construct three different satellite constellations at orbital altitudes of about 340 km. As a general rule, satellites at different altitudes are not operated in synchronization, and it is assumed that there will be no cooperative operation to realize a communication mission. 
     In addition to the three constellations at orbital altitudes of about 340 km, the same business operator plans to construct a constellation at an orbital altitude of about 550 km and a constellation at an orbital altitude of about 1150 km. 
     Furthermore, it needs to be noted that there are factors described below as error factors. 
     &lt;&lt;Time Errors&gt;&gt; 
     
         
         Errors in the clock provided in a satellite 
         System errors in operation tracked and controlled by a ground system 
         Predicted errors and errors in actual orbits 
       
    
     &lt;&lt;Altitude Measurement Errors&gt;&gt; 
     
         
         Measurement errors of the GPS included in a satellite 
         Ranging errors from the ground 
         Measurement errors by the SSA business operator from the ground 
         Errors in high-precision prediction after a precise orbit is decided by a business operator 
       
    
     &lt;&lt;Location Measurement Errors&gt;&gt; 
     
         
         Measurement errors of the GPS included in a satellite 
         Ranging errors from the ground 
         Measurement errors by the SSA business operator from the ground 
         Errors in high-precision prediction after a precise orbit is decided by a business operator 
       
    
     &lt;&lt;Ambiguity Caused by Fluctuation Factors&gt;&gt; 
     
         
         Fluctuations in atmospheric drag 
         Fluctuations in the solar wind 
       
    
       FIGS.  18  to  21    are an example of configurations and usage patterns of orbital altitude information for each category included in the space information recorder  100  according to this embodiment. 
     In  FIGS.  18  to  21   , orbital altitude information is classified according to category, taking into consideration the above factors in altitude fluctuations. 
     The space information recorder  100  includes two or more categories of the following categories. 
     The space information recorder  100  includes information on upper and lower limit values of the orbital altitude or on a nominal altitude and an altitude fluctuation width for each category.
     A category, acquired from the mega-constellation business device  41  which is a management business device of a satellite group constituting a mega-constellation, of different constellations formed at nearby altitudes by the same business operator   A category of a satellite group of each constellation that flies at the same nominal altitude and cooperatively realizes the same mission   A category of multiple orbital planes   A category of each orbital plane of the multiple orbital planes   A category of an individual satellite   

     As illustrated in  FIG.  18   , a category  601  of constellations of multiple business operators includes information of business operators A, B, and so on. 
     In a category  602  of constellations of the same business operator, information on constellations managed by the business operator A is set. 
     For example, information on constellations  340 ,  550 , and  1150  that are managed by the business operator A and respectively have the same altitudes (nominal) is set. 
     The constellation  340  is each constellation with the same altitude (nominal) of 340 km. 
     The constellation  550  is each constellation with the same altitude (nominal) of 550 km. 
     The constellation  1150  is each constellation with the same altitude (nominal) of 1150 km. 
     In a category  603  of different constellations of the same business operator at nearby altitudes, constellation information of each constellation with the same altitude (nominal) is set. 
     For example, information on constellations A, B, and C included in the constellation  340  with the same altitude of 340 km is set. 
     The category  603  of different constellations of the same business operator at nearby altitudes has a category  504  of a constellation group corresponding to the constellation  340 . The category  504  of a constellation group includes an ID of the constellation group and information on upper and lower limit values of the orbital altitude or on a nominal altitude and an altitude fluctuation width. 
     The category  504  of a constellation group corresponding to a same-altitude (nominal) constellation group is used for macro-discussion such as discussion on overall STM, as indicated in  FIG.  19   . 
     In each category  604  of same-altitude (nominal) constellations, information on each same-altitude (nominal) constellation is set. 
     For example, information on each of the constellations A, B, and C included in the constellation  340  with the same altitude (nominal) of 340 km is set. 
     Referring to  FIGS.  18  to  21   , the configuration of each category  604  of same-altitude (nominal) constellations will be described. 
     This will be described using the constellation A as an example. 
     As illustrated in  FIG.  18   , the category  604  of same-altitude (nominal) constellations has a category  503  of a satellite group of each same-altitude (nominal) constellation corresponding to each same-altitude (nominal) constellation. 
     The category  503  of a satellite group includes an ID of the constellation group and information on upper and lower limit values of the orbital altitude or on a nominal altitude and an altitude fluctuation width. 
     The category  503  of a satellite group corresponding to each same-altitude (nominal) constellation is used when an STM business operator detects an intrusion by a space object into a congested region of a mega-constellation, as indicated in  FIG.  19   . 
     In a category  605  of orbital planes included in each same-altitude (nominal) constellation, information on orbital planes included in each same-altitude (nominal) constellation is set. 
     In  FIG.  18   , information on orbital planes A, B, C, and so on included in the constellation A, which is a same-altitude (nominal) constellation, is set. It also has a category  502  of variations in a satellite group in a single orbital plane for each orbital plane. 
     The category  502  of variations in a satellite group in a single orbital plane includes an ID of the orbital plane and information on upper and lower limit values of the orbital altitude or on a nominal altitude and an altitude fluctuation width. 
     The category  502  of variations in a satellite group in a single orbital plane is used for creating a launch plan by a rocket launch business operator or an orbital transfer satellite business operator, as indicated in  FIG.  20   . It is also used for creating a deorbit plan by a satellite business operator or a debris removal business operator that performs PMD, which is deorbit after completion of a mission in orbit. 
     In a category  606  of each orbital plane included in each same-altitude (nominal) constellation, information on individual satellites in each orbital plane included in each same-altitude (nominal) constellation is set. 
     As illustrated in  FIGS.  18  to  21   , the category  606  of each orbital plane included in each same-altitude (nominal) constellation has a category  501  of variations in individual satellites. 
     As illustrated in  FIG.  21   , for example, the category  501  of variations in individual satellites in the orbital plane A included in the constellation A includes an ID of each satellite included in the orbital plane and information on upper and lower limits values of the orbital plane or on a nominal altitude and an altitude fluctuation width. 
     The category  501  of variations in individual satellites is used for collision analysis by the mega-constellation business operator, as indicated in  FIG.  21   . It is also used for determining issuance of a collision alert or a proximity alert by the SSA business operator. 
     Use patterns of the space information recorder  100  according to this embodiment will now be described. 
     When the mega-constellation business device  41  uses the space information recorder  100 , the mega-constellation business device  41  itself can perform highly precise proximity collision because it has high-precision orbit information of its own satellite group in advance. However, it is difficult for the mega-constellation business device  41  to comprehensively handle information on space objects owned by other business operators or debris by including it in the space information recorder  100  of the mega-constellation business device  41 . Therefore, it is rational to acquire a proximity alert, a collision alert, or an alert for an intrusion into a region congested with mega-constellation satellites, as forecast information, from the SSA business operator. 
     &lt;Use of the Space Information Recorder  100  by the SSA Business Device  47 &gt; 
     When the SSA business device  47  uses the space information recorder  100 , it is difficult to update orbit information of all the satellite groups owned by the mega-constellation business operator in real time. Therefore, it is appropriate that the SSA business device  47  analyze and evaluate whether there is a possibility that a space object owned by another business operator or debris will intrude into an area congested with mega-constellation satellites, using information including variations in orbital altitude as a satellite group. 
     If an intrusion into a congested region is foreseen, the SSA business device issues an intrusion alert to the mega-constellation business device and the business device of the space object concerned. Then, the SSA business device acquires high-precision information of the individual satellite for which a collision is foreseen and the satellite group of the orbital plane that includes the individual satellite from the mega-constellation business device. 
     Use of this information allows proximity and collision analysis to be performed for a specific satellite. Thus, if a proximity or collision is foreseen, an intrusion alert is issued to the mega-constellation business operator and the business operator of the space object concerned. 
     If the SSA business device  47  provides high-precision orbit information of the intruding space object together with an intrusion alert to the mega-constellation business operator, the mega-constellation business device can also perform proximity and collision analysis, as described above. 
       FIG.  22    is a diagram illustrating an example of issuance of an alert when debris passes through orbital altitudes of a satellite constellation according to this embodiment. 
     Referring to  FIG.  22   , a procedure for issuing an intrusion alert for passage of debris through a congested region will be indicated. Using the upper and lower limit values of the orbital altitude of the mega-constellation satellite group included in the space information recorder  100 , it is possible to analyze time points and coordinates of an entrance and an exit of an intruding space object in passing through the congested region and a velocity vector. Therefore, the SSA business device  47  notifies this information together with the intrusion alert to the business operators involved. 
     As described above, the danger analysis system  500  that includes the mega-constellation business device  41  and the SSA business device  47  that is used by an SSA business operator performs a danger analysis method with the following procedures. 
     The danger analysis system  500  includes the space information recorder  100  and the management business device  40 , and foresees a collision risk between two space objects among a plurality of space objects in advance so as to avoid a collision.
     A procedure in which the SSA business device  47  issues an intrusion alert for an intrusion by a space object into an orbital altitude region where a mega-constellation is present to the mega-constellation business operator, based on orbital altitude information included in a category of a satellite group. The category of a satellite group refers to a category of a constellation that flies at the same nominal altitude and cooperatively realizes the same mission.   A procedure in which the mega-constellation business device  41  performs danger analysis to analyze danger of a proximity or collision between two space objects for which a collision risk is foreseen, based on the intrusion alert and orbit information of an intruding object that have been acquired from the SSA business device  47 .   

     &lt;Use of the Space Information Recorder  100  by the Rocket Launch Business Device  46 &gt; 
     When the rocket launch business device  46  uses the space information recorder  100 , a notification is made to the mega-constellation business operator with a proximity or collision risk, using orbit information of a satellite group that may fly above a launch lift-off point in a time period in which the launch is planned. In this case, if the rocket launch business device  46  provides high-precision orbit information of a planned flight orbit in the launch to the mega-constellation business operator, the mega-constellation business device  41  can perform highly precise proximity and collision analysis. If a proximity or collision is foreseen, collision avoidance is realized by changing the rocket launch time or by performing a collision avoidance operation on the mega-constellation side. 
     As described above, the danger analysis system  500  that includes the mega-constellation business device  41  and the rocket launch business device  46  that is used by a rocket launch business operator performs the danger analysis method with the following procedures.
     A procedure in which the rocket launch business device  46  notifies the mega-constellation business operator of a launch plan according to which a rocket will pass through an orbital altitude region where a mega-constellation is present, based on orbital altitude information included in the category of a satellite group.   A procedure in which the mega-constellation business device  41  performs danger analysis to analyze danger of a proximity or collision between two space objects for which a collision risk is foreseen, based on the launch plan and orbit information of the rocket that have been acquired from the rocket launch business device.   

     &lt;Use of the Space Information Recorder  100  by the Orbital Transfer Business Device  44 &gt; 
     When a satellite business operator that performs an orbital transfer uses the space information recorder  100 , an orbital transfer satellite may pass through a congested altitude of a mega-constellation during an orbital transfer from the perigee to the apogee of a geostationary transfer orbit GTO. Therefore, if high-precision orbit information of a planned flight orbit of the orbital transfer is provided to the mega-constellation business operator in advance, the mega-constellation business operator can perform highly precise proximity and collision analysis. If a proximity or collision is foreseen, collision avoidance is performed by changing the orbital transfer time or performing a collision avoidance operation on the mega-constellation side. 
     As described above, the danger analysis system  500  that includes the mega-constellation business device  41  and the orbital transfer business device  44  that is used by an orbital transfer business operator that manages a satellite that performs an orbital transfer performs the danger analysis method with the following procedures.
     A procedure in which the orbital transfer business device  44  notifies the mega-constellation business operator of an orbital transfer plan according to which an orbital transfer satellite will pass through an orbital altitude region where a mega-constellation is present, based on orbital altitude information included in the category of a satellite group.   A procedure in which the mega-constellation business device  41  performs danger analysis to analyze danger of a proximity or collision between two space objects for which a collision risk is foreseen, based on the orbital transfer plan and orbit information of the orbital transfer satellite that have been acquired from the orbital transfer business device  44 .   

     &lt;Use of the Space Information Recorder  100  by the Satellite Business Device  43 &gt; 
     When a satellite business operator or debris removal business operator during deorbit uses the space information recorder  100 , a passage through a congested altitude of a mega-constellation may be made in the process of causing descent in orbital altitude from a high altitude and entry into the atmosphere. Therefore, high-precision orbit information of a planned flight orbit of an orbital transfer is provided to the mega-constellation business operator in advance. This allows the mega-constellation business operator to perform highly precise proximity and collision analysis. If a proximity or collision is foreseen, collision avoidance is performed by changing the timing or speed of an orbital effect or by performing a collision avoidance operation on the mega-constellation side. 
     As described above, the danger analysis system  500  that includes the mega-constellation business device  41  and the satellite business device  43  that is used by a satellite business device that is used by a satellite business operator that performs deorbit performs the danger analysis method with the following procedures.
     A procedure in which the satellite business device  43  notifies the mega-constellation business operator of a deorbit plan according to which a deorbiting satellite will pass through an orbital altitude region where a mega-constellation is present, based on orbital altitude information included in the category of a satellite group.   A procedure in which the mega-constellation business device  41  performs danger analysis to analyze danger of a proximity or collision between two space objects, based on the deorbit plan and orbit information of the deorbiting satellite that have been acquired from the satellite business device  43 .   

     &lt;Use of the Space Information Recorder  100  by the Debris Removal Business Device  45 &gt; 
     The danger analysis system  500  that includes the mega-constellation business device  41  and the debris removal business device  45  that is used by a debris removal business operator that manages a debris removal satellite performs the danger analysis method with the following procedures.
     A procedure in which the debris removal business device  45  notifies the mega-constellation business operator of a deorbit plan according to which the debris removal satellite will pass through an orbital altitude region where a mega-constellation is present, based on orbital altitude information included in the category of a satellite group.   A procedure in which the mega-constellation business device  41  performs danger analysis to analyze danger of a proximity or collision between two space objects, based on the deorbit plan and orbit information of the debris removal satellite that have been acquired from the debris removal business device  45 .   

     As described above, the mega-constellation business device  41  includes the space information recorder  100  and executes the danger analysis method according to this embodiment. 
     The SSA business device  47  includes the space information recorder  100  and executes the danger analysis method according to this embodiment. 
     The rocket launch business device  46  includes the space information recorder  100  and executes the danger analysis method according to this embodiment. 
     The satellite business device  43  includes the space information recorder  100  and executes the danger analysis method according to this embodiment. 
     The debris removal business device  45  includes the space information recorder  100  and executes the danger analysis method according to this embodiment. 
     The orbital transfer business device  44  includes the space information recorder  100  and executes the danger analysis method according to this embodiment. 
     DESCRIPTION OF OPERATION 
       FIG.  23    is a flowchart illustrating an example of an intrusion alert process according to this embodiment.  FIG.  22    is a diagram illustrating an example of a predicted orbit of debris that passes through the satellite constellation  20  and an intrusion alert  111  according to this embodiment. 
     Operation of Space Object Intrusion Alert Process S 100   
     In step S 101 , the determination unit  110  determines whether debris will pass through a satellite orbit region  301 , which is an orbit or a region where a plurality of satellites constituting the satellite constellation  20  fly, based on the satellite orbit forecast information  52  and the debris orbit forecast information  53 . Specifically, the satellite orbit region  301  is an orbit where the satellite constellation  20  is formed. If it is determined that debris will pass through the satellite orbit region  301 , the process proceeds to step S 102 . If it is not determined that debris will pass through the satellite orbit region, the process of step S 101  is repeated. 
     In step S 102 , the determination unit  110  generates an intrusion alert  111  including a predicted time, predicted location coordinates, and predicted velocity vector information that relate to passage of the debris. 
       FIG.  22    illustrates a situation in which debris passes through the satellite orbit region  301  where a satellite constellation A at an orbital altitude of A km and a satellite constellation B at an orbital altitude of B km are formed. The determination unit  110  determines whether a predicted orbit of debris passes through a satellite constellation, based on the satellite orbit forecast information  52  and the debris orbit forecast information  53 . In  FIG.  22   , an entrance to and an exit from the satellite constellation A and an entrance to and an exit from the satellite constellation B are passage points of the satellite constellation  20 . 
     The determination unit  110  generates the intrusion alert  111  including a time, coordinates, and a velocity vector that are predicted for passage at each of these four passage points. 
     In step S 103 , the issuance unit  120  notifies the intrusion alert  111  to the management business device  40  used by the management business operator that manages the satellites that fly in the satellite orbit region  301 . Specifically, the issuance unit  120  notifies the intrusion alert to the satellite constellation business device used by the satellite constellation business operator that operates the satellite constellation. The satellite constellation business device is a business operator that conducts a satellite constellation business such as the mega-constellation business device  41 , the LEO constellation business device  42 , or the satellite business device  43 . 
     Collision Avoidance by the Satellite Constellation Forming System 
     The satellite constellation forming system  600  described with reference to  FIGS.  5  to  8    controls the satellite constellation  20  so as to avoid debris that intrudes into the satellite constellation  20 , based on the intrusion alert  111  by the space information recorder  100 . 
     As illustrated in  FIGS.  5  to  8   , the satellite constellation forming system  600  may be installed in the ground facility  700 . In this case, the ground facility  700  controls an avoidance action for avoiding collisions between debris that intrudes into the satellite orbit region  301  and satellites in the satellite constellation  20 , based on the intrusion alert  111  by the space information recorder  100 . 
     With the satellite constellation forming system  600 , the satellite constellation business operator can operate to avoid collisions without significantly disturbing the relative positional relationship among all satellites at least by a method such as accelerating or decelerating all the satellites at the same time. Therefore, the satellite constellation forming system  600  can avoid collisions with debris by the intrusion alert  111  according to this embodiment. 
     DESCRIPTION OF EFFECTS OF THIS EMBODIMENT 
     The danger analysis system according to this embodiment can optimize the amount of information and precision for each purpose of use by displaying orbit information of mega-constellation satellite groups by category. Therefore, the danger analysis system according to this embodiment can shorten the information processing time, reduce human resources, and provide a rational method for realizing collision avoidance for space objects. 
     In the space information recorder according to this embodiment, high-precision orbit information of individual satellites that is used for collision analysis and orbit information that is used by other business operators are classified by category, and the upper and lower limit values are listed for each category by focusing on orbital altitudes. 
     By selecting a category with an amount of information and precision that are appropriate for each purpose of a business operator, it is possible to rationally perform both proximity and collision analysis with coarse precision on a macro level and collision analysis with high precision when a collision is foreseen demonstrably. Therefore, by using the space information recorder according to this embodiment, there is an effect that time is reduced and human resources are reduced due to reduction in labor. 
     OTHER CONFIGURATIONS 
     In this embodiment, the functions of the space information recorder  100  are realized by software. As a modification example, the functions of the space information recorder  100  may be realized by hardware. 
       FIG.  24    is an example of the configuration of the management business device  40  in the danger analysis system  500  according to this embodiment.  FIG.  24    illustrates an example of the configuration of the management business device  40  other than the mega-constellation business device  41 . 
       FIG.  25    is an example of the configuration of the mega-constellation business device  41  in the danger analysis system  500  according to this embodiment. 
     The management business device  40  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 information recorder  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 information recorder  100  may be realized by one electronic circuit, or may be distributed among and realized by a plurality of electronic circuits. 
     As another modification example, some of the functions of the management business device  40  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 information recorder  100  are realized by the processing circuitry. 
     Embodiment 2 
     In this embodiment, differences from Embodiment 1 or 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. 
     When the SSA business operator performs debris collision prediction analysis and finds a risk of proximity or collision with satellites in a mega-constellation, it is rational that the mega-constellation business operator makes a judgment on an avoidance action. Unlike a proximity or collision alert for an individual satellite, an intrusion alert is issued to the mega-constellation business operator as a forecast for passage through orbital altitudes of the mega-constellation. Then, the mega-constellation business operator identifies the satellites concerned and makes a judgment on an avoidance action. Similarly, with respect to an alert for a congested region such as a congested orbital plane or the polar region, it is rational to create a system that issues an intrusion alert for a congested region and also includes outsourcing to a debris removal business operator for a countermeasure action. 
     An arrangement for providing a space object recorder that displays orbit information of satellite groups of mega-constellation business operators by category is required. In addition, a proximity and collision analysis method is required in which the mega-constellation business operator performs proximity and collision analysis with high precision for a space object whose intrusion into a congested region of a mega-constellation satellite group is foreseen based on information in the category of a satellite group. 
     Consideration is being given to securing flight safety for space objects by constructing a public information system called an open architecture data repository (OADR) so as to share information among business operators. 
     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 method” means, for example, a case in which the entities that implement a method, such as the danger analysis method or a 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 danger analysis method” is rephrased, for example, as “the OADR mediates so that the external business devices other than the OADR cooperatively implement the danger analysis method”. Alternatively, “mediates” may be replaced with “provides direction”. 
     Configuration examples of the OADR according to this embodiment will be described below. 
       FIG.  26    is a diagram illustrating an example of a functional configuration of an OADR  800  according to this embodiment. 
     Configuration Example 1 of the OADR 
     The OADR  800  includes the space information recorder  100 . 
     The OADR  800  includes the space information recorder  100  configured as described in Embodiment 1 as a database  810 , which is a public database. 
     The OADR  800  includes the space information recorder  100 , so that there is an effect that danger avoidance can be implemented promptly and rationally by categorizing orbit information on a huge number of satellites of mega-constellation business operators and sharing information among business operators. 
     Configuration Example 2 of the OADR 
     The OADR  800  provides information to and receives information from all or at least one of a mega-constellation business device, an SSA business device, a satellite business device, a debris removal business device, and an orbital transfer business device, and instructs or requests the mega-constellation business device to execute the danger analysis method described in Embodiment 1. 
     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. 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. Therefore, there is an effect that an instruction or request for danger analysis can be made promptly and rationally to the mega-constellation business operator. 
     Configuration Example 3 of the OADR 
     As illustrated in  FIG.  26   , the OADR  800  is a public information system that discloses orbit information of space objects. The OADR  800  includes the database  810  to store orbit information of space objects and a server  820 . The server  820  is referred to also as a space information management server that manages space information. 
     The database  810  includes a first database  811  to store non-public information and a second database  812  to store public information. 
     The server  820 , which is the space information management server, performs danger analysis by referring to the first database  811  and the second database  812 . The server  820  identifies and manages free public information and chargeable public information in the second database  812 . 
     In  FIG.  26   , the database  810  has the configuration of the space information recorder  100 , but it may be a database with a different configuration. 
     Space objects include those whose orbit information is kept non-public due to security needs. When analyzing danger such as a proximity or collision, danger analysis needs to be carried out taking into account non-public information. Therefore, to avoid a risk of information leakage, it is rational to separate databases. 
     In addition, public information may include free public information and chargeable public information, so that it is necessary to identify and manage these types of information when information is disclosed by the OADR. 
     Appropriate information management on a need-to-know basis is possible with the OADR by centrally separating non-public data from public data and then identifying and managing chargeable and free public information. 
     Configuration Example 4 of the OADR 
     The server  820 , which is the space information management server, may perform danger analysis by referring to the first database  811  and the second database  812 , and the server  820  may identify and manage unconditional public information and conditional public information in the second database  812 . 
     When a particular country constructs the OADR as a public institution, it is rational to disclose information unconditionally to business operators of the country concerned and disclose information conditionally to other business operators. As 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 can be set. 
     Configuration Example 5 of the OADR 
     As illustrated in  FIG.  26   , the OADR  800  includes the space information recorder  100  as the database  810 . 
     The space information recorder  100  includes the first database  811  to store public information and the 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 it 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. 
     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. 
     In Embodiments 1 and 2 above, each unit that is a functional element of each device and each system has been described as an independent functional block. 
     However, the configurations of each device and each system may be different from the configurations described in the above embodiments. The functional blocks of each device and each system may be arranged in any configuration, provided that the functions described in the above embodiments can be realized. Each device and each system may be one device or a system composed of a plurality of devices. 
     Portions of Embodiments 1 and 2 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 and 2, portions of Embodiments 1 and 2 may be freely combined, any of the constituent elements may be modified, or any of the constituent elements may be omitted in Embodiments 1 and 2. 
     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;  31 : satellite control device;  32 : satellite communication device;  33 : propulsion device;  34 : attitude control device;  35 : power supply device;  40 : management business device;  41 : mega-constellation business device;  42 : LEO constellation business device;  43 : satellite business device;  44 : orbital transfer business device;  45 : debris removal business device;  46 : rocket launch business device;  47 : SSA 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;  60 : space object;  70 : Earth;  100 : space information recorder;  110 : determination unit;  111 : intrusion alert;  120 : issuance unit;  140 : storage unit;  55 : orbit control command;  301 : satellite orbit region;  500 : danger analysis system;  600 : satellite constellation forming system;  11 ,  11   b : satellite constellation forming unit;  300 : satellite group;  501 ,  502 ,  503 ,  504 ,  601 ,  602 ,  603 ,  604 ,  605 ,  606 : category;  700 : 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;  800 : OADR;  810 : database;  811 : first database;  812 : second database;  820 : server.