JP7664770B2 - Debris removal business equipment - Google Patents

Description

This disclosure relates to debris removal business equipment, ground facilities, and megaconstellation business equipment.

In recent years, the construction of large-scale satellite constellations, so-called mega-constellations, consisting of hundreds to thousands of satellites, has begun, increasing the risk of satellite collisions in orbit. In addition, the amount of space debris, such as satellites that have become uncontrollable due to malfunctions and rocket debris, is increasing.
With the rapid increase in space objects such as satellites and space debris in outer space, there is an increasing need for international rules in space traffic control (STM) to avoid collisions of space objects.

Patent document 1 discloses a technology for forming a satellite constellation consisting of multiple satellites in the same circular orbit.

Conventionally, there is a system in place where the US Combined Space Operations Center (CSpOC) continues to monitor space objects and issues warnings if it predicts that two space objects will approach or collide with each other. Manned space stations and commercial communications satellites respond to these warnings by taking evasive action if deemed necessary.

JP 2017-114159 A

Due to the increase in space debris, the increase in the number of satellites due to the emergence of mega-constellations, and the improvement of ground monitoring capabilities, it is becoming difficult to continue the conventional warning service provided by the U.S. CSPOC. Space Situation Awareness (SSA) is required to determine whether debris will enter the satellite constellation.
However, Patent Document 1 does not describe a method for predicting the intrusion of debris into a satellite constellation.

The objective of this disclosure is to avoid the risk of collisions in satellite constellations by capturing a deorbited space object before it enters a densely populated area and performing collision avoidance operations during orbital descent.

The debris removal business device according to the present disclosure comprises:
A debris removal business device used for managing a debris removal satellite by a debris removal business operator that removes space objects,
The debris removal satellite includes a capture device for capturing a space object, a propulsion device, an orbit control device, and a communication device;
When a space object leaves its orbit and enters the atmosphere,
A region in which the orbit altitude is between 500km and 1000km in the vicinity of 10:30am Local Sun Time (LST) in a sun-synchronous orbit;
A region in the vicinity of the sun-synchronous orbit LST13:30 with an orbit altitude of 500 km to 1000 km.
A region in the vicinity of the sun-synchronous orbit LST06:00 with an orbit altitude of 500km to 1000km.
A region in the vicinity of the sun-synchronous orbit LST 18:00 with an orbit altitude of 500 km or more and 1000 km or less;
An area above 80 degrees north latitude with an orbital altitude of 500km to 1000km,
Before the space object enters a region at latitudes of 80 degrees south or higher and an orbital altitude of 500 km to 1,000 km, the debris removal satellite captures the space object and performs collision avoidance operations during orbital descent.

The debris removal business device according to the present disclosure captures a space object that has de-orbited before it enters a densely populated area, and performs collision avoidance operations during orbital descent. Therefore, the debris removal business device according to the present disclosure has the effect of avoiding the risk of collision in satellite constellations.

An example of multiple satellites providing global communications services to the ground. An example of multiple satellites in a single orbital plane providing an Earth observation service. 1 is a schematic diagram showing an example of a plurality of orbital planes of a satellite constellation according to a first embodiment; 5 is a schematic diagram showing another example of a plurality of orbital planes of a satellite constellation according to the first embodiment. FIG. 2 shows an example of multiple satellites flying in one of the orbital planes of a satellite constellation according to the first embodiment. FIG. 1 is a configuration diagram of a satellite constellation forming system according to a first embodiment. FIG. 2 is a diagram showing the operation of the satellite constellation forming system according to the first embodiment. FIG. 11 is a diagram showing the relative altitude differences of a plurality of orbital planes according to the second embodiment. FIG. 13 is a diagram showing a ground service range of a comparative example. FIG. 13 is a diagram showing a ground service range according to the third embodiment. FIG. 13 is a diagram showing an orbital plane that satisfies the conditions for a sun-synchronous orbit according to the fourth embodiment. 13 shows an example of a satellite constellation formed by a satellite constellation forming system according to embodiment 5. FIG. 2 is a schematic diagram illustrating an example of a collision condition in a satellite constellation. FIG. 2 is a schematic diagram illustrating an example of a collision condition in a satellite constellation. 23 shows an example of a satellite constellation formed by a satellite constellation forming system according to the sixth embodiment. FIG. 23 is a diagram showing the surface service range provided by a satellite constellation in accordance with embodiment 7. FIG. 23 is a diagram showing the timing of polar passing in a satellite constellation according to a seventh embodiment when the number of orbital planes is an even number. FIG. 23 is a diagram showing the timing of polar passing in a satellite constellation according to a seventh embodiment when the number of orbital planes is an odd number. A diagram showing the concept of de-orbiting by free fall. A diagram showing the collision risk when a satellite de-orbits above a satellite constellation. A diagram showing the change in orbital altitude due to acceleration and deceleration of a satellite. A diagram showing the change in orbital inclination angle due to thrust from a thruster. FIG. 23 is a diagram showing the configuration of ground equipment relating to embodiment 10. 23 shows an example of a satellite constellation formed by a satellite constellation forming system according to the sixth embodiment. FIG. 23 is a schematic diagram showing a specific example of a satellite constellation 20 according to an eleventh embodiment. An example of the configuration of satellites in a satellite constellation formation system. An example of the configuration of ground equipment for a satellite constellation formation system. An example of the functional configuration of a satellite constellation formation system. 12 shows an example of the overall configuration of a space traffic management system according to embodiment 12. 12 is a configuration example of a space traffic management device relating to embodiment 12. FIG. 11 is a comparative example of the space traffic management processing example 2, showing a satellite arrangement in an orbital plane. A diagram showing a satellite arrangement in an orbital plane in example 2 of a space traffic management process relating to embodiment 12. A diagram showing multiple orbital planes with the same normal vector but different orbital altitudes. A diagram showing the intrusion of a high-altitude mega-constellation satellite into a dense area (dangerous area) during the satellite orbit descent process. FIG. 23 is a diagram showing a space traffic management process for avoiding intrusion into a crowded area during a satellite orbit descent process in accordance with embodiment 12. FIG. 23 is a diagram showing a configuration example of a debris removal satellite according to a thirteenth embodiment. FIG. 23 is a diagram showing a detailed configuration example of a space traffic management device of a debris removal business apparatus relating to embodiment 13. A diagram showing an example of the configuration of a megaconstellation business device related to embodiment 14. A diagram showing a detailed configuration example of a space traffic management device of a megaconstellation business device relating to embodiment 14. FIG. 2 is a diagram showing an example of the configuration of orbit forecast information according to the first embodiment.

The following describes an embodiment of the present invention with reference to the drawings. In each drawing, the same or corresponding parts are given the same reference numerals. In the description of the embodiment, the description of the same or corresponding parts will be omitted or simplified as appropriate. In addition, the size relationship of each component in the drawings may differ from the actual one. In the description of the embodiment, directions or positions such as "upper", "lower", "left", "right", "front", "rear", "front" and "back" may be indicated. These notations are written in this way only for the convenience of explanation and do not limit the arrangement or orientation of components such as devices, instruments, or parts.

Embodiment 1.
FIG. 1 is a diagram showing an example in which a plurality of satellites cooperate to provide communication services over the entire globe of the Earth 70 .
FIG. 1 shows a satellite constellation 20 that provides global communication services.
The communication service range of each of the multiple satellites flying at the same altitude in the same orbital plane overlaps with the communication service range of the succeeding satellite, so that such multiple satellites can provide communication services to a specific point on the ground by alternating between the multiple satellites on the same orbital plane in a time-division manner.
However, communication services can be provided only in a single orbital plane, which is limited to the area directly below the satellite orbit. Therefore, another orbital plane that rotates in an east-west direction with respect to the earth is provided adjacent to the satellite, and communication services are also provided by multiple satellites on that orbital plane. By providing adjacent orbital planes in this way, communication services to the ground between the adjacent orbits can be provided in a wide area. Similarly, by distributing a large number of orbital planes approximately evenly around the earth, communication services to the ground can be provided over the entire globe. From the perspective of a specific point on the ground, each satellite flies away in a short time. However, if multiple satellites in orbit provide communication services by alternating in a time-division manner, it becomes possible to provide continuous communication services to any point on the ground. In this case, each satellite transmits and receives necessary signals and information using an inter-satellite communication method in order to share communication services with its successor satellite.

When communication services are provided by a satellite constellation orbiting in low earth orbit, the service area of all satellites covers the entire globe, and communication services for any ground user are shared and continued by satellites that fly one after another, taking over signals and information. This ultimately makes it possible to provide continuous communication services to ground users. By equipping each satellite with inter-satellite communication functions in addition to satellite-to-ground communication functions, it becomes possible for signals and information to be handed over between satellites passing nearby. The handover of signals and information that contributes to the mission coordination of communication services will hereafter be referred to as handover.

In a satellite constellation, the orbital altitudes of the different orbital planes are generally all the same. Since the ground speeds of satellites flying at the same orbital altitude are similar, the service range of the ground moves according to the satellite's ground speed while maintaining the relative positions of the service ranges of each satellite. If the service ranges of subsequent satellites in the same orbital plane, or satellites in adjacent orbital planes, cover the Earth's surface comprehensively, the service range will always be maintained as seen from any point on the ground.

FIG. 2 is a diagram showing an example in which multiple satellites in a single orbital plane provide an earth observation service.
FIG. 2 shows a satellite constellation 20 that realizes an earth observation service. In the satellite constellation of FIG. 2, satellites equipped with earth observation equipment, which is a radio wave sensor such as an optical sensor or a synthetic aperture radar, fly at the same altitude in the same orbital plane. In this way, in a satellite group in which the imaging range of the ground is delayed and subsequent satellites overlap, multiple satellites in orbit take turns in a time-division manner to capture ground images for a specific point on the ground, thereby providing an earth observation service. However, the service can be provided in a single orbital plane only in the vicinity directly below the satellite orbit. In contrast, if another orbital plane that rotates in the east-west direction with respect to the earth is placed adjacent to the earth and a similar service is provided by multiple satellites at the same time, it becomes possible to cover the ground service between the adjacent orbits in a planar manner. In the same way, if multiple orbital planes are arranged approximately evenly around the earth, it becomes possible to provide a comprehensive earth observation service over the entire globe. From the perspective of a specific point on the ground, each satellite flies away in a short time, but if multiple satellites in orbit take turns in a time-division manner to provide services, it becomes possible to provide an earth observation service to any point on the ground at any time.

***Configuration Description***
The satellite constellation forming system 100 according to the present embodiment forms a satellite constellation 20 having a plurality of orbital planes 21. In each of the plurality of orbital planes 21, a plurality of satellites 30 fly at the same orbital altitude.

Here, a brief description will be given of the satellite constellation 20 formed by the satellite constellation forming system 100 according to this embodiment.
The satellite constellation 20 according to the present embodiment is composed of a satellite group 300 consisting of a plurality of satellites 30 in each orbital plane 21. In the satellite constellation 20 according to the present embodiment, the satellite group 300 cooperate to provide services. The satellite constellation 20 specifically refers to a satellite constellation consisting of one satellite group provided by a communications business service company as shown in Fig. 1. The satellite constellation 20 specifically refers to a satellite constellation consisting of one satellite group provided by an observation business service company as shown in Fig. 2.

FIG. 3 is a schematic diagram showing an example of a plurality of orbital planes 21 of a satellite constellation 20 according to this embodiment.
3, each of the multiple orbital planes 21 in the satellite constellation 20 exists in substantially the same plane. As an example, each orbital plane 21 may include 20 or more satellites flying as the multiple satellites.

FIG. 4 is a diagram showing another example of a plurality of orbital planes 21 of a satellite constellation 20 according to the present embodiment.
In Fig. 4, each of the orbital planes 21 of the multiple orbital planes in the satellite constellation 20 exists on a different plane from each other. In Fig. 4, the orbital inclination angle of each of the multiple orbital planes 21 is approximately 90 degrees, but the orbital planes are offset. That is, the multiple orbital planes 21 intersect with each other. As an example, each orbital plane 21 may have 20 or more satellites flying as the multiple satellites. Also, the satellite constellation 20 in Fig. 4 may have 20 or more orbital planes 21, as an example.

FIG. 5 shows an example of a plurality of satellites 30 flying in one of the orbital planes 21 of a satellite constellation 20 according to the present embodiment.
A plurality of satellites 30 flying at the same altitude in the same orbital plane fly at the same relative speed while maintaining the relative phase in the orbital plane, so that a plurality of satellites 30 flying at the same altitude in the same orbital plane will not collide with each other.

The configuration of a satellite constellation forming system 100 according to this embodiment will be described with reference to FIG.
The satellite constellation forming system 100 includes a computer. Although Fig. 6 shows the configuration of one computer, in reality, a computer is provided for each of the multiple satellites 30 constituting the satellite constellation 20 and for each of the ground facilities communicating with the satellites 30. The computers provided for each of the multiple satellites 30 and for each of the ground facilities communicating with the satellites 30 work together to realize the functions of the satellite constellation forming system 100 according to this embodiment. An example of the configuration of a computer that realizes the functions of the satellite constellation forming system 100 will be described below.

The satellite constellation forming system 100 includes a processor 910 and other hardware such as a memory 921, an auxiliary storage device 922, an input interface 930, an output interface 940, and a communication device 950. The processor 910 is connected to the other hardware via signal lines and controls the other hardware.

The satellite constellation forming system 100 includes a satellite constellation forming unit 110 as a functional element. The functions of the satellite constellation forming unit 110 are realized by hardware or software.

The processor 910 is a device that executes a satellite constellation formation program. The satellite constellation formation program is a program that realizes the functions of the satellite constellation formation unit 110.
The processor 910 is an integrated circuit (IC) that performs arithmetic processing. Specific examples of the processor 910 include a CPU, a digital signal processor (DSP), and a graphics processing unit (GPU).

The memory 921 is a storage device that temporarily stores data. Specific examples of the memory 921 include a static random access memory (SRAM) and a dynamic random access memory (DRAM).
The auxiliary storage device 922 is a storage device that stores data. A specific example of the auxiliary storage device 922 is a HDD. The auxiliary storage device 922 may also be a portable storage medium such as an SD (registered trademark) memory card, a CF, a NAND flash, a flexible disk, an optical disk, a compact disk, a Blu-ray (registered trademark) disk, or a DVD. Note that HDD is an abbreviation for Hard Disk Drive. SD (registered trademark) is an abbreviation for Secure Digital. CF is an abbreviation for CompactFlash (registered trademark). DVD is an abbreviation for Digital Versatile Disk.

The input interface 930 is a port connected to an input device such as a mouse, a keyboard, or a touch panel. Specifically, the input interface 930 is a Universal Serial Bus (USB) terminal. The input interface 930 may be a port connected to a Local Area Network (LAN).
The output interface 940 is a port to which a cable of an output device such as a display is 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 NIC (Network Interface Card). The satellite constellation forming system 100 communicates between ground facilities and satellites, or between satellites, via the communication device 950.

The satellite constellation formation program is read into the processor 910 and executed by the processor 910. The memory 921 stores not only the satellite constellation formation program but also an OS (Operating System). The processor 910 executes the satellite constellation formation program while executing the OS. The satellite constellation formation program and the OS may be stored in an auxiliary storage device. The satellite constellation formation program and the OS stored in the auxiliary storage device are loaded into the memory 921 and executed by the processor 910. Note that a part or all of the satellite constellation formation program may be incorporated into the OS.

The satellite constellation forming system 100 may include multiple processors that replace the processor 910. These multiple processors share the task of executing the satellite constellation forming program. Each processor is a device that executes the satellite constellation forming program, just like the processor 910.

The data, information, signal values and variable values used, processed or output by the satellite constellation formation program are stored in memory 921, auxiliary storage device 922, or in a register or cache memory within processor 910.

The "part" of the satellite constellation forming part 110 may be read as a "processing", "procedure" or "step". Also, the "processing" of the satellite constellation forming process may be read as a "program", a "program product" or a "computer-readable storage medium on which a program is recorded".
The satellite constellation forming program causes a computer to execute each process, procedure, or step of the above-mentioned satellite constellation forming unit, where "unit" is replaced with "process,""procedure," or "step." Also, the satellite constellation forming method is a method performed by the satellite constellation forming system 100 executing the satellite constellation forming program.
The satellite constellation forming program may be provided by being stored in a computer-readable recording medium or a storage medium, or may be provided as a program product.

*** Operation Description ***
The operation of the satellite constellation forming system 100 according to this embodiment will be described with reference to FIG.

In step S101, parameters are set in the satellite constellation forming system 100 so that the orbital altitudes of the orbital planes 21 of the satellite constellation 20 are different from each other.
In step S102, the satellite constellation forming unit 110 forms a satellite constellation 20 in which the orbital altitudes of the orbital planes 21 of the multiple orbital planes are different from each other. The satellite constellation forming unit 110 forms the satellite constellation 20 in which the orbital altitudes of the orbital planes 21 are different from each other using preset parameters. As an example, 20 or more satellites may fly as the multiple satellites on each orbital plane 21. Also, the satellite constellation 20 in FIG. 4 may have 20 or more orbital planes 21, as an example.

The following is a more detailed explanation of the case where the satellite constellation forming unit 110 forms a satellite constellation 20 (see FIG. 4) in which each of the multiple orbital planes 21 exists on a different plane from the others. As described above, the multiple satellites 30 of the satellite constellation 20 in FIG. 4 provide services to points on the ground in a time-division alternating manner.

To prevent collisions by flying at different orbital altitudes, it is necessary to consider not only the dimensions and shapes of the two objects, but also the accuracy of positioning during tracking and control on the ground. For example, if the dimensions of the objects are around 1m and their exact positions are known, a collision can be avoided by maintaining an altitude difference of 3m or more. However, if there are errors in the four elements of position coordinates and time (x, y, z, t), the possibility of collision remains.

It is believed that a satellite constellation operator can maintain a positioning accuracy of about 100 m for their satellites at any time. Therefore, by setting the altitude difference between different orbital planes to 200 m or more, a satellite constellation 20 having multiple orbital planes 21 with different orbital altitudes according to this embodiment can be formed. Alternatively, with some leeway, the altitude difference between different orbital planes can be set to 300 m or more to form a satellite constellation 20 having multiple orbital planes 21 with different orbital altitudes according to this embodiment. For a satellite constellation 20 with about 20 orbital planes, the satellite constellation forming unit 110 can construct the satellite constellation 20 with an altitude difference of about 6 km.

On the other hand, if a satellite operator who does not possess a method for improving satellite positioning avoids collisions based on public information, it is expected that the positioning accuracy at any time will deteriorate from 500 m to about 1 km. Therefore, by setting the altitude difference between different orbital planes to 2 km or more, it is possible to form a satellite constellation 20 having a plurality of orbital planes 21 with different orbital altitudes according to this embodiment. Alternatively, with a margin, it is also possible to form a satellite constellation 20 having a plurality of orbital planes 21 with different orbital altitudes according to this embodiment by setting the altitude difference between different orbital planes to 3 km or more. If the satellite constellation 20 has about 20 orbital planes, the satellite constellation forming unit 110 can construct the satellite constellation 20 with an altitude difference of about 60 km.
In recent years, a technology for monitoring orbital objects called Space Situation Awareness (SSA) has been attracting attention. If this technology improves monitoring accuracy, known as the Space Fence concept, it will be possible for satellite operators who do not have a method for improving satellite positioning to realize satellite constellations with reduced altitude differences.

Next, a more detailed explanation will be given of the case where the satellite constellation forming unit 110 forms a satellite constellation 20 (see FIG. 3) in which each of the multiple orbital planes 21 exists on the same plane. As described above, the multiple satellites 30 of the satellite constellation 20 in FIG. 3 provide services to points on the ground in a time-division alternating manner.

Unlike communication services, the earth observation service realized by the satellite constellation 20 in FIG. 3 does not necessarily need to continue the service at all times. On the other hand, the earth observation service requires "capturing any point anywhere at any time". For this reason, it is preferable to configure the satellite constellation 20 with satellites equipped with earth observation equipment equipped with a device that changes the viewing direction at least in the cross-track direction perpendicular to the satellite's traveling direction. In this way, by providing the satellite with a viewing direction changing function that includes the distance between adjacent orbits above the equator, it becomes possible to image any point on the globe at any time and anywhere. Compared to a satellite constellation using individual fixed-view earth observation equipment, there is an effect that the satellite constellation can be constructed with a smaller number of orbital planes, which makes it possible to reduce the system construction cost.
In addition, it is not necessary for the imaging field of view to be covered in the direction of satellite flight, and if imaging is possible by changing the field of view of subsequent satellites or satellites in adjacent orbital planes, it is possible to reduce the number of satellites in the same orbital plane. If the field of view change range is about 2000 km on the Earth's surface, it may be possible to cover the entire globe with just two or three satellites per orbital plane.

***Other configurations***
In this embodiment, the functions of the satellite constellation forming unit 110 are realized by software. As a modification, the functions of the satellite constellation forming unit 110 may be realized by hardware.

The satellite constellation forming system 100 includes an electronic circuit in place of the processor 910 .
The electronic circuit is a dedicated electronic circuit that realizes the functions of the satellite constellation forming unit 110.
Specifically, the electronic circuit 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. ASIC is an abbreviation for Application Specific Integrated Circuit. FPGA is an abbreviation for Field-Programmable Gate Array.
The functions of the satellite constellation forming unit 110 may be realized by a single electronic circuit, or may be realized by distributing the functions among multiple electronic circuits.
As another modification, some of the functions of the satellite constellation forming unit 110 may be realized by electronic circuits, and the remaining functions may be realized by software.

Each of the processor and electronic circuitry is also called processing circuitry. In other words, in the satellite constellation forming system 100, the functions of the satellite constellation forming unit 110 are realized by the processing circuitry.

***Description of Effects of This Embodiment***
In the satellite constellation forming system according to the present embodiment, multiple satellites in orbit provide services to a specific point on the ground in a time-division alternating manner. In any orbital plane, multiple satellites fly at the same altitude and at approximately equal intervals. Furthermore, a satellite constellation is formed that is made up of multiple orbital planes with different orbital altitudes.

In the satellite constellation forming system according to the present embodiment, satellites flying at the same altitude in the same orbital plane fly at the same relative speed while maintaining the relative phase in the orbital plane, so they do not collide. In addition, in different orbital planes, although there is a possibility of collision at the intersection of the two planes, satellites flying at different orbital altitudes do not collide. In this way, if the orbital altitudes are different in different orbital planes, there is an effect that the risk of collision can be avoided for all satellites in the satellite constellation.
As with the satellite constellation according to the present embodiment, satellites flying in the same orbital plane at different orbital altitudes do not collide with each other, even between different satellite constellations. Therefore, the basic concept according to the present embodiment is also effective in collision avoidance for multiple satellite constellations. In STM, where the need for international rule-making in the congested space has been appealed in recent years, there is an effect of providing a method for multiple satellite constellations to coexist and avoid collisions. In other words, according to the satellite constellation forming system according to the present embodiment, there is an effect of being able to avoid satellite collisions even when a huge number of satellites, such as several thousand satellites, are densely concentrated at nearby altitudes.

Embodiment 2.
In this embodiment, the following mainly describes differences or additions from embodiment 1. Note that the same components as those in embodiment 1 are given the same reference numerals, and the description thereof may be omitted.

In this embodiment, we will explain how the satellite constellation forming unit 110 forms a satellite constellation 20 in which the relative altitude difference between adjacent orbital planes in a plurality of orbital planes is sinusoidal.

FIG. 8 is a diagram showing the relative altitude differences of a plurality of orbital planes according to this embodiment.
Fig. 8 shows the relative altitude difference of each orbital plane in the satellite constellation 20 having 17 orbital planes. The vertical axis shows that the altitude of orbital plane 1 is high and the altitude decreases in descending order, and does not show distance. Fig. 8 shows that when the orbital plane 1 is used as the reference, the orbital altitude difference between adjacent orbital planes 1 and 2, the orbital altitude difference between orbital planes 2 and 3, etc. are plotted, a sine wave is formed.

If the altitudes of adjacent orbital planes differ significantly, the handover distance for inter-satellite communications becomes long, and the driving angle range for matching the communication antennas becomes wide, which is a disadvantage. In contrast, with the satellite constellation 20 according to this embodiment, the altitude difference between adjacent orbits is limited, so the relative difference changes gradually. This makes it easier to perform handovers that contribute to mission coordination with nearby satellites.

In addition, in an earth observation satellite, for example, the image quality of an optical sensor depends on the satellite altitude, so that a small difference in altitude between adjacent orbits has the effect of obtaining high-quality images with no inconsistency between image scenes.
A satellite constellation equipped with an optical sensor capable of acquiring images of the Earth's surface and imaging a wider area than the adjacent orbital distance above the equator can acquire images of the entire globe. Since the resolution and observation width of an optical sensor depend on the orbital altitude, a satellite constellation using an optical sensor with the same specifications will have the highest resolution and the smallest observation width when imaging at the lowest orbital altitude. Therefore, if the observation width of an optical sensor at the lowest orbital altitude above the equator is greater than the adjacent orbital distance, it will be possible to comprehensively image the Earth's surface, including above the equator.

When the altitudes of adjacent orbits differ significantly, discontinuity accompanied by differences in resolution at the seams of images is likely to become apparent. However, the satellite constellation forming system according to this embodiment limits the difference in altitude between adjacent orbits, which has the effect of making it possible to acquire global image data with good image quality without noticeable seams in the images. Another characteristic is that the greater the difference in satellite altitude, the faster the relative movement speed of the ground service area. Therefore, the satellite constellation forming system according to this embodiment can minimize the amount of relative movement of adjacent service areas, which makes it easier to transfer data to a subsequent satellite, a process known as handover in communications, and makes it easier to suppress errors.

Embodiment 3.
In this embodiment, a description will be given mainly of differences or additions from the embodiments 1 and 2. Note that the same components as those in the embodiments 1 and 2 are given the same reference numerals, and the description thereof may be omitted.

In this embodiment, the satellite constellation forming unit 110 forms a satellite constellation 20 in which the radius of the ground service range per satellite is equal to or greater than approximately √2/2 the distance between adjacent orbits above the equator. Specifically, in this satellite constellation 20, the radius of the ground service range per satellite in the orbital plane with the lowest orbital altitude ensures coverage of approximately √2/2 or more of the distance between adjacent orbits above the equator.

FIG. 9 is a diagram showing a ground service range of a comparative example.
When the relative position of the satellite is optimal, if the radius of the ground service range is secured to be equal to the distance between adjacent orbits above the equator, the service range can cover the entire globe. Also, if the satellite altitude is the same in all orbital planes, the relative relationship of the service area is maintained, so it is possible to continue the service covering the entire globe at all times. However, in orbital planes with different orbital altitudes, the satellite's traveling speed differs depending on the satellite altitude, so that the service area secured comprehensively when the relative position of the satellite is optimal may move relative to the satellite, resulting in a gap P, that is, an area that cannot be serviced.

Figure 9 shows the ground service ranges of three orbital planes. The radius ra of the ground service range is half the distance Ra between adjacent orbits above the equator. In this case, as shown in Figure 9, if the ground service range of the middle orbital plane shifts 45 degrees forward, an area (gap) that cannot be serviced will be created.

FIG. 10 is a diagram showing the ground service range according to this embodiment.
In Fig. 10, the radius rb of the ground service range is √2/2 of the distance Rb between adjacent orbits above the equator. In this case, as shown in Fig. 10, even if the ground service ranges of each orbital plane are shifted by 45 degrees, no area (gaps) that cannot be serviced will occur.

As described above, according to the satellite constellation forming system of this embodiment, even when the satellite relative positioning is in the worst state, i.e., when the service area of the adjacent orbit is located approximately 45 degrees forward, no gaps in the service area occur. Therefore, according to the satellite constellation forming system of this embodiment, even if the service area of the adjacent orbit moves relatively in the satellite's direction of flight, it is possible to continue to provide uninterrupted, globally comprehensive service.

Embodiment 4.
In this embodiment, a description will be given mainly of differences or additions from the embodiments 1 to 3. Note that the same components as those in the embodiments 1 to 3 are given the same reference numerals, and the description thereof may be omitted.

In this embodiment, the satellite constellation forming unit 110 will describe a mode in which the satellite constellation 20 is formed in which the orbital altitude of each of the multiple orbital planes satisfies the condition of a sun-synchronous orbit. In addition, the satellite constellation forming unit 110 will describe a mode in which the satellite constellation 20 is formed in which the orbital altitude of each of the multiple orbital planes is composed of only sun-synchronous quasi-recurrent orbits.

FIG. 11 is a diagram showing an orbital plane that satisfies the conditions for a sun-synchronous orbit according to this embodiment.
It is desirable for optical satellites of Earth observation satellites to continue observation under conditions of almost the same solar incidence angle. For this reason, satellite orbits called sun-synchronous satellites are often used. In the orbit of a sun-synchronous satellite, the angle between the normal to the orbital plane, which rotates once a year in synchronization with the revolution of the Earth, and the direction of the Sun is almost constant. In addition, the orbit of a sun-synchronous satellite is an orbit in which the local time (LST) of the Earth is the same throughout the year.
The orbital altitudes where the conditions for a sun-synchronous orbit are satisfied exist intermittently. In this embodiment, a satellite constellation 20 is formed in which the orbital plane is composed of only orbital altitudes that satisfy the conditions for a sun-synchronous orbit. With such a satellite constellation 20, each orbital plane can continue to provide service at the desired LST, and a satellite constellation without a collision risk can be realized.

The brightness and S/N characteristics of images taken by optical sensors change depending on the angle of incidence of sunlight. For this reason, sun-synchronous orbits are often used to provide continuous Earth observation services under conditions of a constant angle of incidence of sunlight on the orbital plane. Furthermore, the orbital plane between LST 10:00 and 11:00 is often used because it ensures a sufficient amount of light and there is no direct reflection from the sea surface. However, satellites around LST 10:30 alone cannot capture images "anytime, anywhere." Therefore, it is effective to increase the frequency of imaging by combining satellites in orbital planes with different LSTs.

For example, in addition to LST 10:30, add orbital planes at LST 9:00 and LST 12:00. In this case, there is a possibility that imaging can be performed approximately every 90 minutes, and assuming that it takes about 90 to 100 minutes for a low-orbit satellite to orbit the Earth once, there is an effect of improving the imaging frequency of any point, including the imaging opportunity of the next orbit. Furthermore, if the number of satellites in the same orbital plane increases, it becomes possible to cover the entire area, and if the LSTs are evenly distributed with the same idea, imaging can be performed "anytime, anywhere" in principle.
Incidentally, an optical sensor that can only capture visible images cannot capture images at night, but an infrared sensor or radio wave sensor can capture images at any time, including nighttime.

A satellite constellation equipped with an optical sensor capable of acquiring images of the Earth's surface and capturing an image of a wider area than the distance between adjacent orbits above the equator can acquire images of the entire globe. The resolution and observation width of an optical sensor depend on the orbital altitude, so in the case of a satellite constellation employing an optical sensor of the same specifications, the highest resolution and the smallest observation width are obtained when the image is captured at the lowest orbital altitude. Therefore, if the observation width of the optical sensor at the lowest orbital altitude above the equator is greater than the distance between adjacent orbits, comprehensive imaging of the Earth's surface, including above the equator, is possible. In addition, if the altitudes of adjacent orbits differ significantly, discontinuity due to differences in resolution at the seams of the images is likely to become apparent. However, even in this embodiment, by adopting the satellite constellation according to embodiment 2, the altitude difference between adjacent orbits is limited, and global image data with good image quality and inconspicuous seams can be acquired.

***Modification of this embodiment***
As a modified example of this embodiment, a mode will be described in which the satellite constellation forming unit 110 forms a satellite constellation 20 in which the orbital altitude of each of a plurality of orbital planes is composed of only sun-synchronous quasi-recurrent orbits.

A sun-synchronous subrecurrent orbit is an orbit in which the satellite's ground projection line revisits the orbit after multiple orbits, and is often used for Earth observation satellites. The orbital altitudes that meet the conditions for a sun-synchronous subrecurrent orbit are a subset of the orbital altitudes that meet the conditions for a sun-synchronous orbit.
The satellite constellation 20, in which the orbital altitudes of each of the multiple orbital planes are composed only of sun-synchronous quasi-recurrent orbits, makes it easier to plan operations, image capture, and data processing for repeated, regular observation of the same point over a long period of time using an earth observation satellite. Moreover, it has the effect of realizing a satellite constellation without a collision risk.

If the number of recurrence days is not important, the orbital altitude of the sun-synchronous quasi-recurrence orbit can be, for example, about 540 km (recurrence every 15 days), about 539 km (recurrence every 14 days), about 537 km (recurrence every 13 days), about 535 km (recurrence every 12 days), about 533 km (recurrence every 11 days), about 530 km (recurrence every 10 days), etc. With these six orbital planes, the satellite constellation 20 can be realized with a maximum altitude difference of about 10 km.
Furthermore, for example, if the orbit is configured with only a 13-day recurrence orbit, then satellite constellation 20 can be realized with six orbital planes and a maximum altitude difference of approximately 115 km if configured with orbits of approximately 537 km, approximately 514 km, approximately 491 km, approximately 467 km, 445 km, and approximately 422 km.

Embodiment 5.
In this embodiment, the following mainly describes differences or additions from embodiment 1. Note that the same components as those in embodiment 1 are given the same reference numerals, and the description thereof may be omitted.

FIG. 12 is a diagram showing an example of a satellite constellation 20 formed by the satellite constellation forming system 100 according to this embodiment.
The satellite constellation 20 according to the present embodiment is composed of a group of satellites 300. In the satellite constellation 20, the group of satellites 300 cooperate with each other to provide services. The satellite constellation 20 has a plurality of orbital planes 21 in which a plurality of satellites 30 fly at the same orbital altitude.
Moreover, in the satellite constellation 20 according to this embodiment, the orbital altitudes of the orbital planes 21 of the multiple orbital planes are the same, and the orbital planes 21 of the multiple orbital planes exist on different planes from each other.

In the satellite constellation 20 shown in FIG. 12, the orbital inclination angle of each of the multiple orbital planes 21 is approximately 90 degrees, and each of the multiple orbital planes 21 exists on a different plane from the others. Therefore, in the satellite constellation 20 shown in FIG. 12, the multiple orbital planes 21 intersect in the polar regions.

13 and 14 are schematic diagrams showing an example of collision conditions in a satellite constellation.
Satellites flying at the same altitude in the same orbital plane will not collide because they fly at the same speed while maintaining the relative phase in the orbital plane. However, satellites flying at the same orbital altitude in different orbital planes may collide at the intersection points where the orbital altitudes match on the orbital plane intersection lines, as shown in Figures 13 and 14. In particular, as shown in Figure 14, low-orbit satellites flying at an orbital altitude of about 100 km to 2000 km and with an orbital inclination angle of about 90 degrees have intersection points near the polar regions, so there is a risk of collision near the polar regions of the North Pole and the South Pole.

However, if the timing of satellites passing through intersections is always offset, two objects will not collide. The satellite constellation forming unit 110 forms a satellite constellation 20 in which two objects will not collide. Specifically, the time at which a satellite flying in both orbital planes passes an intersection between different orbital planes is a multiple of "waiting time T1 until the next satellite arrives/number of orbital planes" in the same orbital plane, and a satellite passing time does not coincide at any intersection between any two orbital planes.

The satellite constellation 20 shown in Fig. 12 has an orbital inclination angle of about 90 degrees and has a plurality of orbital planes that are different from each other. In this satellite constellation 20, all satellites in all orbital planes pass near the polar regions. Therefore, the satellite constellation forming unit 110 makes the satellites fly at intervals of "waiting time T1 until the next satellite arrives/number of orbital planes" in the same orbital plane, and staggers the polar pass times of the satellites in the plurality of orbital planes.
Specifically, assuming that it takes about 100 minutes for a low earth orbit satellite to complete one revolution, if 20 satellites fly per orbital plane, it takes about 5 minutes from when a satellite passes a specific point until the succeeding satellite arrives. If there are 20 orbital planes, the satellite constellation 20 according to this embodiment can be realized by shifting the time by 15 seconds, which is equal intervals of 300 seconds.

In the satellite constellation 20 formed by the satellite constellation forming system 100 according to this embodiment, multiple satellites in the same orbital plane fly synchronously at the same altitude, and satellites in different orbital planes also have the same orbital altitude and maintain the same satellite speed. Therefore, if the satellites in each orbital plane are initially set to pass through the intersection at different times in all orbital planes, the relative timing is always maintained, which has the effect of avoiding the risk of collision between any two satellites in all orbital planes.

In this embodiment, an example of timing is shown in which the waiting time until the next satellite arrives is evenly spaced according to the number of orbital planes. However, there are various ways to select the interval for shifting the polar crossing timing and the order of the orbital planes.

Embodiment 6.
In this embodiment, differences or additional points from embodiment 5 will be mainly described. Note that the same components as those in embodiment 5 are given the same reference numerals, and the description thereof may be omitted.

15 and 24 are diagrams showing examples of a satellite constellation 20 formed by the satellite constellation forming system 100 according to this embodiment.
In the satellite constellation 20 shown in Figures 15 and 24, the orbital inclination angle of each of the multiple orbital planes 21 is not approximately 90 degrees, and each of the multiple orbital planes 21 exists on a different plane from each other. In this satellite constellation 20, any two orbital planes intersect at a point other than the polar regions. Therefore, the satellite constellation forming unit 110 forms the satellite constellation 20 so that the time at which a satellite of each of the orbital planes passes through an intersection between different orbital planes is a multiple of "waiting time T1 until the next satellite arrives/number of orbital planes" of the same orbital plane, and the satellite passing times do not coincide at any intersection between any two orbital planes.

As shown in Figures 15 and 24, the intersections of multiple orbital planes with an orbital inclination angle of more than 90 degrees move away from the polar regions depending on the orbital inclination. In addition, depending on the combination of orbital planes, intersections may exist in various positions, including near the equator. Therefore, compared to the satellite constellation of embodiment 5, the locations where collisions may occur are more diverse. However, since the number of intersections does not increase, the collision probability does not increase with the diversification of locations. When many satellites fly synchronously on the same orbital plane, if the satellite passing timing of the two orbital planes is shifted at a specific intersection to avoid collisions between two specific orbital planes, the satellites in these two orbits will not collide with each other. However, it should be noted that there remains a risk that a subsequent satellite will collide with a satellite in another orbital plane. It is necessary to check by exhaustive testing for any orbital planes that the intersection passing timing does not match, and if the problem cannot be solved by timing adjustment, it is necessary to change either the orbital plane or the number of satellites in one orbital plane. Note that if it is confirmed that there are no collisions at all intersections, the satellites in all orbital planes and between the orbital planes will operate synchronously thereafter, which has the effect of avoiding the risk of collision.

In this embodiment, an example of timing is shown in which the waiting time until the next satellite arrives is evenly spaced according to the number of orbital planes. However, there are various ways to select the interval for shifting the polar crossing timing and the order of the orbital planes.

Here, as a specific example, an example of an earth observation satellite adopting a sun-synchronous quasi-recurrent orbit with an orbital inclination of about 98 degrees and an orbital period of about 98 minutes will be described. When a multi-satellite constellation is constructed using this orbit, all orbital planes will not meet in the polar regions because the orbital inclination is inclined at about 98 degrees. However, there is always an intersection line between two different orbital planes, and an intersection point exists at the same altitude, so a collision risk still exists. Furthermore, since a collision risk exists in all combinations of two different orbital planes, in this embodiment, collisions are avoided by shifting the satellite pass timing at an intersection point between any two planes.
Furthermore, there are also earth observation satellites that fly at an orbital inclination angle of about 45 degrees, and in this orbit, they become sun-synchronous satellites. In the case of a low orbital inclination angle, the intersection of two different orbital planes is located at a low latitude, and there is a possibility that intersections will occur at multiple latitudes. Depending on the combination of the number of orbital planes and the number of satellites flying in one orbital plane, collisions cannot always be avoided. Therefore, in the satellite constellation 20 according to this embodiment, a combination of the number of orbital planes and the number of satellites per orbital plane that does not cause collisions at all intersections of two orbital planes is found, and then the passing timing at each intersection is maintained to avoid collisions.
If the number of satellites increases extremely, the brute force collision avoidance calculations become complicated, so the first embodiment in which the satellites are configured using different orbital planes may be adopted.

Embodiment 7.
In this embodiment, differences or additional points from embodiment 5 will be mainly described. Note that the same components as those in embodiment 5 are given the same reference numerals, and the description thereof may be omitted.

In this embodiment, a method of shifting the waiting time of satellites in the case of the satellite constellation 20 of FIG. 14 in which multiple orbital planes intersect at the polar regions will be described. In this embodiment, when the multiple orbital planes are numbered in the order in which they are arranged, the waiting time until the arrival of the succeeding satellite at the polar crossing timing is shifted by about half for the odd-numbered orbital planes and the even-numbered orbital planes. In other words, the waiting time for the even-numbered orbital planes and the waiting time for the odd-numbered orbital planes are shifted by about half (the waiting time). By forming the satellite constellation 20 in this way, the terrestrial service range is alternately arranged between the adjacent odd-numbered and even-numbered planes, which has the effect of rationally covering the terrestrial service range.

FIG. 16 is a diagram showing the surface service range provided by the satellite constellation 20 according to this embodiment.
16 shows an example in which the number of orbital planes is 18, and the angle of the orbital planes changes by 10 degrees relative to each other. As the polar crossing timing, the waiting time until the arrival of the succeeding satellite is divided into 18 equal parts, and the polar crossings are shifted from timing 1 for odd-numbered planes and from timing 10 for even-numbered planes, so that the ground service area alternates between even-numbered and odd-numbered planes to fill in the gaps, which has the effect of comprehensively covering the earth's surface.

FIG. 17 is a diagram showing the polar passing timing when the number of orbital planes is an even number in the satellite constellation 20 according to this embodiment.
FIG. 18 is a diagram showing the polar passing timing when the number of orbital planes is an odd number in the satellite constellation 20 according to this embodiment.
As shown in Figures 17 and 18, in the satellite constellation 20 according to this embodiment, it is preferable that the number of orbital planes is an odd number. In the example of Figure 17, the service area of plane 1 adjacent to plane 18 is adjacent to each other, which may cause inconsistency in covering the whole globe. Therefore, by making the number of orbital planes an odd number as shown in Figure 18, the terrestrial service areas of the last plane and plane 1 are alternately arranged like the others, which has the effect of rationally covering the whole globe.

Embodiment 8.
In this embodiment, the following description will be mainly focused on the points added to the embodiments 1 to 7. Note that the same reference numerals are used to designate the same configurations as those in the embodiments 1 to 7, and the description thereof may be omitted.

In this embodiment, we will explain variations of debris removal methods that allow satellites to de-orbit while avoiding collisions.

FIG. 19 is a diagram showing the concept of de-orbiting by free fall.
FIG. 20 is a diagram showing the collision risk when a satellite above the satellite constellation 20 de-orbits.

<Debris removal method example 1>
The debris removal method of Example 1 according to this embodiment includes a capture device or external force application device for changing the orbital plane of a failed satellite that has become uncontrollable due to a malfunction or the like before the failed satellite descends and passes through an orbital plane where satellites are densely packed, and a propulsion device for propelling the failed satellite.

The sun-synchronous quasi-recurrent orbit from 10:00 LST to 11:00 LST has a relationship between the solar incidence angle and the orbital plane that is ideal for imaging with optical sensors for Earth observation, and is a dense orbital plane on which many optical Earth observation satellites fly. The orbital altitude is ideal for high-resolution imaging, and is concentrated at around 500 km to 1000 km where atmospheric resistance is low. However, there are also cases where ultra-low altitude satellites fly at orbital altitudes of around 200 km.

There are cases where a satellite constituting the satellite constellation 20 described in the first to seventh embodiments malfunctions and becomes uncontrollable. In this case, the malfunctioning satellite passes through a dense orbital plane while changing its orbital altitude in the process shown in FIG. 19, during which the malfunctioning satellite free falls from a high altitude, such as an orbital altitude of 1000 km to 2000 km, enters the Earth's atmosphere and disappears. In this case, as shown in FIG. 20, there is a high risk of collision because the malfunctioning satellite may meet with satellite groups at multiple orbital altitudes. Therefore, the debris removal method according to the present embodiment has the effect of avoiding collisions in the dense orbit by changing the orbital plane in advance so as not to pass through the dense orbit.

FIG. 21 is a diagram showing the change in orbital altitude due to acceleration and deceleration of a satellite.
FIG. 22 is a diagram showing the change in orbit inclination angle by the thrust of the propulsion device.
A specific example of a debris removal method is to use a debris removal satellite equipped with a capture device for capturing other satellites and a propulsion device for providing thrust to the other satellites to capture the malfunctioning satellite and to artificially change its orbit using the propulsion device. Note that debris removal satellites are also called debris recovery satellites.
If the satellite accelerates in the direction of travel, the orbital altitude temporarily rises, and the orbital plane rotates around the Earth's approximate axis due to the effect of perturbation in a cycle different from that of the dense orbit, making it possible to avoid the dense orbital plane. If the satellite decelerates in the direction of travel, the orbital altitude temporarily drops, and the orbital plane rotates around the Earth's approximate axis due to the effect of perturbation in a cycle different from that of the dense orbit, making it possible to avoid the dense orbital plane. Depending on the time allowance until the malfunctioning satellite is predicted to pass through the dense orbit, a collision avoidance method can be selected, either to descend before meeting with the dense orbit or to descend after passing through the dense orbit. This has the effect of reliably avoiding collisions. However, the method using perturbation has the disadvantage of a long residence time, so a method of actively firing the propulsion device to rotate the orbital plane in the out-of-plane direction is also possible. In this case, a large amount of propellant is consumed, so the debris removal method, including the propulsion tank, becomes large.

Note that recovery of the satellite itself is equivalent to recovery of a so-called cooperative target. Therefore, it is effective for the debris removal satellite to be equipped with an attachment that is compatible with the debris removal method in advance to facilitate capture. It is also effective for the debris removal satellite to transmit information informing the position of the satellite itself or the capture target, making it easier for the satellite to approach or join up. However, there are exceptions in cases where the satellite has lost control and is rotating.

<Debris removal method example 2>
The debris removal method of Example 2 according to this embodiment includes a capture device or external force imparting device for changing the orbital plane of an object floating at an altitude of about 100 km to 2000 km while describing an elliptical orbit, before the object passes through the orbital plane that constitutes the satellite constellation, and a propulsion device for imparting a thrust to the object. Note that the external force imparting device may include not only "force" but also "torque" or even "change in mass characteristics" accompanying merging as "external force". The external force imparting device is also called an external disturbance imparting device.

Removing obstacles is an issue for STMs. If the orbital plane of an object flying in an elliptical orbit coincides with the orbital plane of many satellites flying in nearly circular orbits at a specific orbital altitude, the risk of collision becomes very high. The debris removal method of Example 2 of this embodiment has the effect of safely removing obstacles with a high risk of collision.

Specific examples of debris removal methods are the same as those in <Debris Removal Method Example 1>. In <Debris Removal Method Example 1>, in order to capture the satellite itself, it is possible to equip it in advance with attachments that make it easy to capture as a so-called cooperative target. However, floating objects other than the satellite itself are so-called non-cooperative targets, and are difficult to capture, such as objects with complex shapes, rotating objects, heavy objects, or objects that do not have an appropriate structure for capture. For this reason, the capture device that should be equipped must be highly advanced. Specific examples that can be realized include a method of grasping with a robot, a method of enveloping the target in a capture net-like device, and a method of piercing and pulling a harpoon-like rod with a wire.

Embodiment 9.
In this embodiment, differences or additional points from the first to eighth embodiments will be mainly described. Note that the same components as those in the first to eighth embodiments are given the same reference numerals, and the description thereof may be omitted.

In this embodiment, we will explain a variation of a satellite constellation construction method in which the debris removal method described in Example 1 or Example 2 of the debris removal method of Embodiment 8 is applied to a satellite constellation constructed by the satellite constellation formation system described in Embodiments 1 to 7.

<Satellite constellation construction method example 1>
In example 1 of the satellite constellation construction method according to the present embodiment, a component satellite is inserted into an orbit at an orbital altitude that is different from the orbital altitude at which the satellites in the nearby orbital plane fly, and is in a different orbital plane near the orbital plane of the component satellites that make up the satellite constellation 20. In example 1 of the satellite constellation construction method, the component satellite is added by increasing or decreasing the speed to change the orbital altitude and the angle of the orbital plane about the Earth's axis.

In the process of constructing a given satellite constellation by launching satellites in order, there is a high risk of collision in the process of launching an additional satellite into an orbital plane after a large number of satellites have been launched. In Example 1 of the satellite constellation construction method according to this embodiment, it is possible to significantly reduce the risk of collision during launch by launching an additional satellite into an orbit with a slight shift in the orbital plane of an already launched satellite. Furthermore, it is possible to gradually approach the desired orbit from a satellite altitude that does not match the altitude of the already launched satellite, thereby reducing the risk of collision during the transitional phase.

<Satellite constellation construction method example 2>
In the satellite constellation construction method example 2 according to the present embodiment, a database is provided that collects in advance information on the orbit, orbital altitude, number of flying satellites, etc., adopted by other countries' systems or similar systems. In the satellite constellation construction method example 2 according to the present embodiment, a satellite is put into orbit at an orbital altitude different from the orbital altitude at which the satellites in the nearby orbital plane fly, which is different from the orbital plane in which the existing satellites fly and is in a different orbital plane in the vicinity of the orbital plane of the component. In the satellite constellation construction method example 2 according to the present embodiment, the component satellites are added by increasing or decreasing the speed to change the orbital altitude and the angle of the orbital plane around the earth's axis.

According to example 2 of the satellite constellation construction method of this embodiment, multiple satellite constellations are constructed, and the effect is that a satellite constellation can be constructed without the risk of collision in an environment where the entire space is congested.

In addition, in the example 1 of the satellite constellation construction method, a data processing device for the orbit and position of the satellite itself is provided on the ground.
In addition, in the second example of the satellite constellation construction method, a data processing device for the orbit and position of a flying object in space is provided on the ground.

Embodiment 10.
In this embodiment, the following description will be mainly focused on the points added to the first to ninth embodiments. Note that the same reference numerals are used to designate the same configurations as those in the first to ninth embodiments, and the description thereof may be omitted.

In this embodiment, a variation of a ground facility 500 that transmits an orbit control command 51 to a satellite 30 that constitutes a satellite constellation 20 and that has reached the end of its design life will be described. The orbit control command 51 is a command to deorbit the satellite 30 by operating a propulsion device equipped on the satellite 30.

<Example 1 of Ground Equipment 500>
FIG. 23 is a diagram showing a configuration of example 1 of a ground facility 500 according to the present embodiment.
The configuration of example 1 of ground equipment 500 is similar to that of embodiment 10.

The communication device 950 transmits and receives signals for tracking and controlling the satellites 30 that make up the satellite constellation 20 .
The orbit control command transmitter 510 transmits an orbit control command 51 to a satellite 30 that is to be de-orbited due to, for example, reaching the end of its design life.
The analysis and prediction unit 520 analyzes and predicts the passing orbit of the satellite 30 after receiving the deorbit command.

As a specific example, a case will be described in which the analysis prediction unit 520 determines that the satellite 30 will pass through an orbital plane near LST10:30 of a congested orbit in a sun-synchronous orbit at an orbital altitude of 500 km to 800 km. At this time, the orbit control command transmission unit 510 transmits to the satellite 30 an orbit control command 51 for performing active de-orbit operation to avoid collision risk by shifting the timing of passing through the congested orbit or the orbital plane. When the satellite 30 receives the orbit control command 51, the satellite 30 increases or decreases the orbital altitude by increasing or decreasing the satellite speed by the orbit control device equipped in the satellite 30. Alternatively, the satellite 30 changes the orbital inclination angle by applying acceleration in the out-of-plane direction of the orbital plane by thrusting the thruster in a direction approximately perpendicular to the satellite's traveling direction. In this way, the satellite 30 performs active de-orbit operation to avoid collision risk by shifting the timing of passing through the congested orbit or the orbital plane.

In constructing mega-constellations, as a measure to prevent the total amount of debris in space from increasing indefinitely, the necessity of making PMD (Post-Mission Disposal) mandatory and deorbiting, for example, 99% or more of satellites from orbit is being discussed. In addition, since the probability that a satellite will be in good condition at the end of its life must be taken into consideration, the necessity of ADR (Active Debris Removal) to deorbit satellites that cannot be deorbited autonomously due to the end of their life or loss of function due to a malfunction is also being discussed.
However, PMD and ADR only appeal to the necessity of a method of letting the satellite fall freely and burn up in the atmosphere, and do not have a method of avoiding the case of passing through a congested orbit on the way down. In addition, in the case of geostationary orbit satellites, when the risk of debris collision is predicted, there are cases where the satellite that is hit takes action to avoid the collision by publishing the predicted orbit information of the debris together with a collision warning. However, in the case of low-orbit satellites, when a different satellite constellation is constructed, there is a high risk that the avoidance action of the satellite that is hit becomes a secondary collision cause. In other words, there is a risk of collision with satellites in front and behind when parallel parking, or collision with a group of satellites at different altitudes in the same plane.
In addition, there is a high possibility that many satellites that will be hit will pass through the area in a short period of time. If multiple satellites take evasive action simultaneously, it will become difficult to predict the behavior of nearby satellites, resulting in a risk of a collision.
In addition, as a result of the evasive maneuver, not only the orbital altitude and in-plane phase of the orbit will change, but also the LST will move due to the rotation of the orbital plane, which may make it difficult to return to normal or may cause a risk of disruption to the continuity of the services intended by the satellite constellation.
Furthermore, there may be many satellites in flight, such as CubeSats, which are experimental satellites that do not have an avoidance function.
In addition, if the accuracy of orbit prediction due to free fall is poor, the area and time period in which a collision warning should be issued may become wide and long, causing the struck satellite to issue collision warnings frequently and making it unable to respond.

According to example 1 of the ground equipment 500 of this embodiment, even during altitude descent due to deorbiting, orbital control during descent is possible, which has the effect of avoiding passage through congested orbits and thus avoiding collisions. In addition, it has the effect of avoiding collisions even if the satellite that is hit does not take evasive action.

<Example 2 of Ground Equipment 500>
In Example 2 of the ground facility 500 of this embodiment, a capture command 52 and an orbit control command 51 for deorbiting a malfunctioning satellite that has lost its orbit control function are transmitted to the debris removal satellite 31. The debris removal satellite 31 is, for example, a satellite equipped with a device for recovering a satellite that has lost its orbit control function due to a malfunction. The debris removal satellite 31 is equipped with a capture device for capturing the malfunctioning satellite and a propulsion device.

Example 2 of the ground equipment 500 transmits a capture command 52 and an orbit control command 51 to the debris removal satellite 31 to deorbit the failed satellite by operating the capture device and propulsion device equipped on the debris removal satellite.
The communication device 950 transmits and receives signals for tracking, controlling and operating the debris removal satellites.
The orbit control command transmitter 510 transmits an orbit control command 51 or a capture command 52 .
The analysis and prediction unit 520 analyzes and predicts the passing orbit of the debris removal satellite in a state in which the failed satellite has been captured.

As a specific example, a case will be described in which the analysis prediction unit 520 determines that the debris removal satellite 31 will pass through an orbital plane of a congested orbit in a sun-synchronous orbit near LST10:30 at an orbital altitude of 500 km to 800 km. At this time, the orbit control command transmission unit 510 transmits an orbit control command 51 to the debris removal satellite 31 to perform active de-orbit operation to avoid collision risk by shifting the timing of passing through the congested orbit or the orbital plane. When the debris removal satellite 31 receives the orbit control command 51, the satellite 30's orbit control device increases or decreases the satellite speed to increase or decrease the orbital altitude. Alternatively, the satellite 30 changes the orbital inclination angle by applying acceleration in the out-of-plane direction of the orbital plane by thrusting the thruster in a direction approximately perpendicular to the satellite's traveling direction. In this way, the debris removal satellite 31 performs active de-orbit operation to avoid collision risk by shifting the timing of passing through the congested orbit or the orbital plane.

According to example 2 of the ground equipment 500 of this embodiment, the constituent satellites of the satellite constellation are already equipped with equipment such as attachments for capturing the debris removal satellites. Therefore, example 2 of the ground equipment 500 of this embodiment is effective in recovering the constituent satellites of the satellite constellation.

<Example 3 of Ground Equipment 500>
In example 3 of the ground equipment 500 according to this embodiment, the communication device 950 sends and receives signals to track, control and operate a debris removal satellite equipped with a device for recovering rocket debris flying above a congested orbit with an orbital altitude of 800 km or more.
The orbit control command transmitter 510 transmits a capture command and an orbit control command to the debris removal satellite to deorbit the rocket remains by operating the capture device and propulsion device equipped on the debris removal satellite.
The analysis and prediction unit 520 analyzes and predicts the passing orbit of the debris removal satellite after capturing the rocket remnants.

As a specific example, a case will be described in which the analysis prediction unit 520 determines that the satellite will pass through an orbital plane in the vicinity of LST 10:30 of a congested orbit in a sun synchronous orbit at an orbital altitude of 500 km to 800 km.
In Example 3 of the ground facility 500 according to this embodiment, the orbit control device equipped on the satellite increases or decreases the satellite speed to raise or lower the orbital altitude, or changes the orbital inclination by applying acceleration in the out-of-plane direction of the orbital plane by thrusting the thruster in a direction approximately perpendicular to the satellite's traveling direction. Then, in Example 3 of the ground facility 500 according to this embodiment, active de-orbit operation is performed to avoid the risk of collision by shifting the timing of passing through a congested orbit or the orbital plane.

Rocket debris does not usually have a capture attachment for the debris removal satellite, and it is difficult to capture because it rotates in orbit, making it more technically difficult than ground equipment example 2. According to ground equipment example 3 of this embodiment, the capture device can be a method of wrapping it in a net-like object like a cast net, a method of piercing and pulling a harpoon-like rod with a wire, or a method of adhering to the outer skin of the object to be captured with a sticky substance or adhesive. Even if a satellite constellation component satellite equipped with a capture attachment is deorbited, if it is allowed to fall freely without attitude control, the attitude becomes unstable, so there is a high possibility that the debris removal satellite will not be able to easily access the capture attachment. In such cases, the capture device of ground equipment example 3 of this embodiment of the present invention is effective.

<Example 4 of Ground Equipment 500>
Here, as explained in Examples 1 to 3 of the ground equipment 500, a case will be described in which the analysis prediction unit 520 determines that the satellite will pass through a polar dense area of another satellite constellation constructed at a low altitude during descent to de-orbit the satellite or to de-orbit for debris collection (debris removal).
In Example 4 of the ground facility 500, the orbital inclination angle is changed by applying acceleration in the out-of-plane direction of the orbital plane by jetting the thrusters in a direction approximately perpendicular to the satellite's traveling direction so that the orbital inclination angle is different from that of the satellite constellation. As a result, in Example 4 of the ground facility 500, the inclination of the orbital plane is changed from that of the congested orbit, or the passing timing is shifted to perform active de-orbit operation to avoid the risk of collision.

Examples 1 to 3 of ground equipment 500 not only cover the congested orbit avoidance around LST10:30, but also avoid collisions when passing through the polar congested area.

The above ground equipment 500 examples 1 to 4 may be implemented in any combination. For example, the following ground equipment may be implemented.

The ground facility includes a communication device that transmits and receives signals for tracking and controlling the satellites that make up the satellite constellation, an orbit control command transmitter that transmits an orbit control command, and an analysis and prediction unit that analyzes and predicts the passing orbit of the satellite after receiving a de-orbit command. The ground facility transmits the orbit control command to de-orbit the satellite that has reached the end of its design life by operating a propulsion device equipped on the satellite.
When analytical predictions reveal that the satellite will pass through a polar dense area or a congested orbital plane of another satellite constellation constructed at a low altitude during descent to deorbit the satellite or to deorbit the satellite for debris collection, the ground facility performs active deorbit operation to avoid the risk of collision. Specifically, the ground facility performs active deorbit operation to avoid the risk of collision by changing the inclination of the orbital plane from that of the congested orbit by applying acceleration in an out-of-plane direction of the orbital plane by thrusting the thrusters in a direction approximately perpendicular to the satellite's direction of travel so that the orbital inclination angle is different from that of the satellite constellation, thereby changing the inclination of the orbital plane from that of the congested orbit or by shifting the timing of the passage.

The ground facility includes a communication device for transmitting and receiving signals to track, control and operate the debris removal satellite equipped with a device for recovering a satellite that has failed and lost its orbit control function, an orbit control command transmitter, and an analysis and prediction unit for analyzing and predicting the passing orbit of the debris removal satellite in a state in which the failed satellite has been captured. The ground facility transmits a capture command and an orbit control command to the debris removal satellite to cause the failed satellite to deorbit by operating the capture device and propulsion device equipped on the debris removal satellite.
When analytical predictions reveal that the satellite will pass through a polar dense area or a congested orbital plane of another satellite constellation constructed at a low altitude during descent to deorbit the satellite or to deorbit the satellite for debris collection, the ground facility performs active deorbit operation to avoid the risk of collision. Specifically, the ground facility performs active deorbit operation to avoid the risk of collision by changing the inclination of the orbital plane from that of the congested orbit by applying acceleration in an out-of-plane direction of the orbital plane by thrusting the thrusters in a direction approximately perpendicular to the satellite's direction of travel so that the orbital inclination angle is different from that of the satellite constellation, thereby changing the inclination of the orbital plane from that of the congested orbit or by shifting the timing of the passage.

The ground facility includes a communication device for transmitting and receiving signals to track, control and operate the debris removal satellite equipped with a device for recovering rocket debris flying above a congested orbit with an orbital altitude of 800 km or more, an orbit control command transmitter, and an analysis and prediction unit for analyzing and predicting the passing orbit of the debris removal satellite after capturing the rocket debris. The ground facility transmits a capture command and an orbit control command to the debris removal satellite to cause the rocket debris to deorbit by operating the capture device and propulsion device equipped on the debris removal satellite.
When analytical predictions reveal that the satellite will pass through a polar dense area or a congested orbital plane of another satellite constellation constructed at a low altitude during descent to deorbit the satellite or to deorbit the satellite for debris collection, the ground facility performs active deorbit operation to avoid the risk of collision. Specifically, the ground facility performs active deorbit operation to avoid the risk of collision by changing the inclination of the orbital plane from that of the congested orbit by applying acceleration in an out-of-plane direction of the orbital plane by thrusting the thrusters in a direction approximately perpendicular to the satellite's direction of travel so that the orbital inclination angle is different from that of the satellite constellation, thereby changing the inclination of the orbital plane from that of the congested orbit or by shifting the timing of the passage.

Here, the effects of this embodiment will be further described.
The general method for deorbiting a low-orbit satellite is to operate a thruster in the opposite direction to the satellite's direction of travel to lower its orbital altitude and burn it up by re-entering the atmosphere. However, the mega-satellite constellations currently being planned have orbital altitudes of 1000 km or more, which are higher than low-orbit satellites, so there is a risk of colliding with satellites flying at lower orbital altitudes when deorbiting at the end of their life or when they have a malfunction.
In addition, because megasatellite constellations have a variety of orbital planes and many satellites fly in formation on each orbital plane, the orbital paths that satellites pass through when deorbiting are also diverse. The probability of collision is high, especially when there is a possibility of passing through congested areas of low-orbit satellites, such as near LST10:30 in a sun-synchronous orbit or in the polar regions.
If deorbiting relies on free fall, the orbital plane will rotate as the altitude gradually decreases, so a satellite deorbited from any orbital plane may pass through a congested orbit of sun-synchronous satellites.
In addition, when deorbiting a satellite in a satellite constellation whose orbital plane has an inclination of approximately 90 degrees and passes near the polar regions, the orbital inclination remains roughly the same even if the orbital altitude is lowered, so there is a high probability of collision with a polar orbit satellite in a lower orbit.

In this embodiment, in order to avoid passing through a congested orbital plane, the rotation of the orbital plane is used to hasten the descent before passing through the congested orbit, or conversely, to drop (pass) through a quiet orbital plane after the congested orbital plane has passed, thereby avoiding collisions. As a method for changing the timing of passing through a congested orbital plane, accelerating the satellite to be deorbited will raise the orbital altitude and delay the descent timing. Also, decelerating will accelerate the descent of the orbital altitude, so the descent timing can be advanced. In addition, the orbital plane rotates due to perturbation depending on the residence time at the orbital altitude, making it possible to wait for the passage of the congested orbit. Note that the orbital inclination angle can be changed by operating the thrusters in a direction perpendicular to the direction of travel when the satellite to be deorbited passes through the ascending node or descending node, so it is also possible to accelerate the rotation of the orbital plane.

In particular, in Example 4 of the ground facility 500, the orbital inclination angle is intentionally changed to avoid collisions at altitudes where the polar regions are congested, by changing the orbital plane so as not to pass through the polar regions. The orbital inclination angle can be effectively changed by operating the thrusters in a direction perpendicular to the direction of travel when the satellite to be de-orbited passes through the ascending node or descending node.

Next, the effects of the above-mentioned first to tenth embodiments will be further described.
In recent years, plans for large-scale satellite constellations involving several thousand satellites have been announced, but there is a risk that satellites flying at the same altitude will collide at two points where the satellite altitudes coincide on the intersecting line of the orbital planes. In large-scale constellations, the probability of collision is extremely high, especially in the polar regions where all orbital planes meet with a high probability.
A well-known example of multiple satellites flying in the same orbital plane is the geostationary orbit satellite, which flies above the equator at an orbital altitude of about 36,000 km, with about 300 satellites flying in the same orbital plane. Because they are synchronized with the rotation of the Earth, they appear to be stationary in space when viewed from the ground, but because they fly in a nearly circular orbit at the same altitude, satellites in geostationary orbit do not collide and continue to operate. Also, because the angle from the Earth is only about 1 to 2 degrees apart, it feels like they are close to each other, but the distance between two satellites in orbit is sufficient.

In contrast, in low-earth-orbit satellite constellations, which have been increasing in recent years, the number of satellites in a single constellation is on the scale of several thousand, and the total number of satellites in a multi-satellite constellation concept approaches 10,000. The orbital altitude is about 1/20 to 1/100 times lower than that of a geostationary satellite, and the distance between the two satellites is also much closer, so there is a higher risk of collision compared to geostationary orbit.
Also, unlike geostationary orbits, because different orbital planes are used simultaneously, there is a possibility of collisions at the intersection of the two planes. In a satellite constellation with an orbital inclination of nearly 90 degrees, multiple orbital planes intersect near the Earth's axis, and all satellites pass over the Antarctic and North Pole, so there is a high possibility of collisions if the orbital altitudes coincide.
In addition, the sun-synchronous orbit between 10:00 and 11:00 LST, which is commonly used by Earth observation satellites, has many orbital planes where satellites are densely packed, and there is a high risk of collision if an object that gradually changes its orbital altitude enters the same orbital plane.
In addition, in the completed form of the satellite constellation, no collision will occur unless the position coordinates and time of any two satellites are simultaneously the same, i.e. (x1, y1, z1, t1) = (x2, y2, z2, t2). Therefore, collisions can be avoided by artificially manipulating the orbital altitude, timing, or phase in the orbital plane. However, during the transitional stage of constructing a satellite constellation, there is a high risk of collision in the process of adding a new satellite to the constellation.
In addition, if a satellite flying at a higher altitude than many satellite constellations experiences an uncontrollable malfunction and falls freely, there is a high risk of collision if it passes through a dense orbital plane while changing altitude, as it may meet with multiple groups of satellites at orbital altitudes within the same orbital plane.

Because outer space is so vast, the absolute probability of a collision is still sufficiently small, but once a collision occurs, large-scale destruction will occur, and the large amount of scattered debris will collide with satellites flying nearby, causing secondary damage. In the worst case scenario, there is a concern that the entire nearby orbit will be violated due to a chain reaction of collisions and destruction.
If the entire nearby orbit were to be violated and a large amount of debris were to become airborne, there would be a risk that no satellites would be able to operate for a long period of time, which would have a negative impact on social life as a whole, as our dependence on space infrastructure increases.
In addition, satellites themselves are expensive, and the total cost of launching them by rocket and operating them is enormous, so a collision would result in huge economic losses.
Furthermore, because multiple satellites work together to achieve goals such as communication services, the loss of a satellite due to a collision will result in the interruption of the originally intended service and a deterioration in quality.

In the above-mentioned embodiments 1 to 10, collisions of satellite constellations can be avoided by providing methods such as combining orbital planes with different altitudes, artificially shifting the time of intersections, removing malfunctioning satellites, and injecting new satellites into orbit.

Embodiment 11.
In this embodiment, the following description will be mainly focused on the points added to the embodiments 1 to 10. Note that the same reference numerals are used to designate the same configurations as those in the embodiments 1 to 10, and the description thereof may be omitted.

As described in the first embodiment, the satellite constellation forming system 100 is composed of the satellite group 300, and the satellite group 300 cooperate to form the satellite constellation 20 that provides a service. The satellite constellation forming system 100 forms the satellite constellation 20 having a plurality of orbital planes in each orbital plane 21, in which a plurality of satellites fly at the same orbital altitude.
The satellite constellation forming unit 110 according to this embodiment forms a satellite constellation 20 in which the orbital altitudes of the orbital planes 21 are different from one another and each orbital plane has an orbital inclination angle that makes the orbital periods of the orbital planes 21 equal to one another. For example, each of the orbital planes is a sun-synchronous orbit as shown in FIG. 11 .

The satellite constellation forming system 100 has parameters set so that the orbital altitudes of the orbital planes 21 of the satellite constellation 20 are different from each other, and each orbital plane has an orbital inclination angle such that the orbital periods of each of the orbital planes 21 of the multiple orbital planes are equal to each other.
Then, using the set parameters, the satellite constellation forming unit 110 forms a satellite constellation 20 in which the orbital altitudes of each orbital plane 21 are different from each other and each orbital plane has an orbital inclination angle such that the orbital periods of each orbital plane 21 of the multiple orbital planes are equal to each other.

FIG. 25 is a schematic diagram showing a specific example of a satellite constellation 20 according to this embodiment.
Sun-synchronous orbital planes have the same orbital period even if they have different orbital altitudes. Below are examples of multiple orbital planes with different orbital altitudes that result in a sun-synchronous orbit. The constraints for sun synchronization are largely determined by the correlation between the orbital altitude and the orbital inclination, so a sun-synchronous orbit can be formed by appropriately setting the orbital inclination according to the orbital altitude.
Orbital altitude 1000km: Orbital inclination approximately 99.5°
Orbital altitude 1100km: Orbital inclination approximately 99.9°
Orbital altitude 1200km: Orbital inclination approximately 100.4°
Orbital altitude 1300km: Orbital inclination approximately 100.9°
Orbital altitude 1400km: Orbital inclination approximately 101.4°
Orbital altitude 1500km: Orbital inclination approximately 102.0°

For example, if the orbital planes for the above six types of orbital altitudes are set as follows in the LST, a group of orbital planes that differ from each other in the latitudinal direction by approximately 30 degrees will be formed, and the relative angles between these orbital planes will always be maintained. In other words, six orbital planes with the same revolution period will be formed.
Sun-synchronous orbit at an altitude of 1000 km: LST06:00
Sun-synchronous orbit at an altitude of 1,100 km: LST 08:00
Sun-synchronous orbit at an altitude of 1200 km: LST 10:00
Sun-synchronous orbit at 1300km altitude: LST 12:00
Sun-synchronous orbit at 1,400 km altitude: LST 14:00
Sun-synchronous orbit at an altitude of 1500 km: LST 16:00

Here, we have given an example of a sun-synchronous orbit as a typical example of an orbit with equal orbital periods, but even in the case of a sun-asynchronous orbit, it is possible to select multiple orbital altitudes that will result in equal orbital periods.

The satellite constellation forming unit 110 may form a satellite constellation 20 in which the orbital altitudes of the orbital planes 21 of the multiple orbital planes are different from each other, and each orbital plane has an orbital inclination angle at which the rotation of each orbital plane 21 of the multiple orbital planes is synchronized.

Next, a ground facility 500 that tracks and controls the satellite constellation 20 constructed by the satellite constellation forming system 100 according to this embodiment will be described.
The ground equipment 500 according to this embodiment adjusts the altitude of each satellite so as to maintain the relative phase of the multiple satellites in each of the multiple orbital planes, and generates commands to adjust the orbital altitude and orbital inclination of each orbital plane so as to maintain the relative angles between the multiple orbital planes, and transmits the commands to each satellite in the satellite constellation.

<Example 5 of Ground Equipment 500>
FIG. 23 is a diagram showing a configuration of an example 5 of the ground equipment 500 which is the ground equipment 500 according to the present embodiment.
The configuration of example 5 of the ground equipment 500 is similar to example 1 of the ground equipment 500 of embodiment 10.

The communication device 950 transmits and receives signals for tracking and controlling the satellites 30 that make up the satellite constellation 20 .
The orbit control command transmitter 510 transmits to the satellite 30 an orbit control command 51 that adjusts the altitude of each satellite so as to maintain the relative phase of the multiple satellites in each of the multiple orbital planes, and adjusts the orbital altitude and orbital inclination of each orbital plane so as to maintain the relative angle between the multiple orbital planes.

***Description of Effects of This Embodiment***
The orbital periods of orbital planes with different orbital altitudes and the same orbital inclination angle are different. Therefore, the relative angle between the orbital planes changes over a long period of operation. As a result, when multiple satellites cooperate to provide a service, the satellite configuration may change, causing a risk of disruption to the service. In addition, when the orbital plane is adjusted using a separate thruster to maintain an appropriate orbital configuration, there is a risk that the service may not be able to continue during the adjustment period.
According to the satellite constellation forming system of this embodiment, the relative relationship between the orbital planes is maintained, so it is possible to avoid the risk of collision while continuing to provide services without any problems.

Embodiment 12.
In this embodiment, the following will be mainly described with respect to the points added to or different from the first to eleventh embodiments. Note that the same reference numerals are used to designate the same configurations as those in the first to eleventh embodiments, and the description thereof may be omitted.

***Configuration Description***
FIG. 26 shows an example of the configuration of a satellite 30 of a satellite constellation forming system 600.
Here, the configuration of the satellites 30 that form the satellite constellation forming system 600 will be described.
The satellite 30 comprises a satellite control device 310, a satellite communication device 32, a propulsion device 33, an attitude control device 34, and a power supply device 35. The satellite 30 also comprises other components for implementing various functions, but Fig. 26 will explain the satellite control device 310, the satellite communication device 32, the propulsion device 33, the attitude control device 34, and the power supply device 35. The satellite 30 is an example of a space object 60.

The satellite control device 310 is a computer that controls the propulsion devices 33 and the attitude control device 34, and includes a processing circuit. Specifically, the satellite control device 310 controls the propulsion devices 33 and the attitude control device 34 in accordance with various commands transmitted from the ground facility 500. The satellite control device 310 is an orbit control device that controls the orbit of the satellite 30 by controlling the propulsion devices 33 and the attitude control device 34 in accordance with various commands transmitted from the ground facility 500.
The satellite communication device 32 is a device that communicates with the ground facility 500. Specifically, the satellite communication device 32 transmits various data related to its own satellite to the ground facility 500. In addition, the satellite communication device 32 receives various commands transmitted from the ground facility 500.
The propulsion device 33 is a device that provides propulsive force to the satellite 30 and changes the speed of the satellite 30. Specifically, the propulsion device 33 is an apogee kick motor, a chemical propulsion device, or an electric propulsion device. The apogee kick motor (AKM) is an upper stage propulsion device used to put an artificial satellite into orbit, and is also called an apogee motor (when a solid rocket motor is used) or an apogee engine (when a liquid engine is used).
Chemical propulsion systems are thrusters that use monopropellant or bipropellant fuels. Electric propulsion systems are ion engines or Hall thrusters. An apogee kick motor is a device used for orbital transfer, and can be a type of chemical propulsion system.
The attitude control device 34 is a device for controlling attitude elements such as the attitude of the satellite 30, the angular velocity of the satellite 30, and the line of sight (Line of Sight). The attitude control device 34 changes each attitude element to a desired direction. Alternatively, the attitude control device 34 maintains each attitude element in a desired direction. The attitude control device 34 includes an attitude sensor, an actuator, and a controller. The attitude sensor is a device such as a gyroscope, an earth sensor, a sun sensor, a star tracker, a thruster, and a magnetic sensor. The actuator is a device such as an attitude control thruster, a momentum wheel, a reaction wheel, and a control moment gyro. The controller controls the actuator according to measurement data of the attitude sensor or various commands from the ground equipment 500.
The power supply unit 35 includes devices such as a solar cell, a battery, and a power control device, and supplies power to each device mounted on the satellite 30 .

The processing circuitry provided in the satellite control device 310 will now be described.
The processing circuitry may be dedicated hardware or may be a processor that executes a program stored in a memory.
In the processing circuit, some functions may be realized by dedicated hardware and the remaining functions may be realized by software or firmware, i.e. the processing circuit may be realized by hardware, software, firmware or a combination thereof.
The dedicated hardware may specifically be a single circuit, a complex 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, and FPGA is an abbreviation for Field Programmable Gate Array.

FIG. 27 shows an example of the configuration of the ground equipment 500 provided in the satellite constellation forming system 600.
The ground equipment 500 controls programs of multiple satellites in all orbital planes. The ground equipment 500 is an example of a ground device. The ground equipment is composed of a ground station such as a ground antenna device, a communication device connected to the ground antenna device, or a computer, and ground equipment as a server or terminal connected to the ground station via a network. The ground equipment may also include a communication device mounted on a moving object such as an aircraft, a self-propelled vehicle, or a mobile terminal.

The ground equipment 500 forms the satellite constellation 20 by communicating with each satellite 30. The ground equipment 500 is provided in the space traffic management device 200. The ground equipment 500 includes a processor 910 and other hardware such as a memory 921, an auxiliary storage device 922, an input interface 930, an output interface 940, and a communication device 950. The processor 910 is connected to the other hardware via signal lines and controls the other hardware. The hardware of the ground equipment 500 is similar to the hardware of the satellite constellation forming system 100 described in FIG. 6.

The ground equipment 500 has, as its functional elements, an orbit control command transmission unit 510 and an analysis and prediction unit 520. The functions of the orbit control command transmission unit 510 and the analysis and prediction unit 520 are realized by hardware or software.

The communication device 950 transmits and receives signals for tracking and controlling each satellite 30 of the group of satellites 300 that make up the satellite constellation 20. The communication device 950 also transmits orbit control commands 55 to each satellite 30.
The analysis and prediction unit 520 analyzes and predicts the orbit of the satellite 30 .
The orbital control command transmitter 510 generates the orbital control command 55 to be transmitted to the satellite 30 .
The orbit control command transmission unit 510 and the analysis prediction unit 520 realize the functions of the satellite constellation formation unit 11. That is, the orbit control command transmission unit 510 and the analysis prediction unit 520 are an example of the satellite constellation formation unit 11.

FIG. 28 is a diagram showing an example of the functional configuration of the satellite constellation forming system 600.
The satellite 30 further includes a satellite constellation forming unit 11b that forms the satellite constellation 20. The satellite constellation forming unit 11b of each of the multiple satellites 30 and the satellite constellation forming unit 11 provided in each of the ground facilities 500 work together to realize the functions of the satellite constellation forming system 600. The satellite constellation forming unit 11b of the satellite 30 may be provided in the satellite control device 310.

FIG. 29 shows an example of the overall configuration of a space traffic management system 800 according to this embodiment.
The space traffic management system 800 includes a plurality of space traffic management devices 200 .
Each of the plurality of space traffic control devices 200 is implemented in the business device 40 of each of a plurality of businesses that manage space objects 60 flying in space. The plurality of space traffic control devices 200 are connected to each other by communication lines.

FIG. 30 is a diagram showing an example of the configuration of a space traffic management device 200 according to this embodiment.
The space traffic management device 200 communicates with other business devices 40. The space traffic management device 200 may be mounted on a ground facility 500. The space traffic management device 200 may also be mounted on a satellite constellation forming system 600.

The business device 40 provides information about a space object 60 such as an artificial satellite or debris. The business device 40 is a computer of an operator that collects information about a space object 60 such as an artificial satellite or debris.
The business equipment 40 includes equipment such as a megaconstellation business equipment 41, a LEO constellation business equipment 42, a satellite business equipment 43, an orbital transfer business equipment 44, a debris removal business equipment 45, a rocket launch business equipment 46, and an SSA business equipment 47. LEO is an abbreviation for Low Earth Orbit.

The mega-constellation business device 41 is a computer of a mega-constellation business operator that operates a large-scale satellite constellation, i.e., a mega-constellation business. For example, the mega-constellation business device 41 is a business device that manages a constellation of 100 or more satellites.
The LEO constellation business device 42 is a computer of a LEO constellation operator that operates a low earth orbit constellation, i.e., a LEO constellation business.
The satellite business device 43 is a computer of a satellite operator that handles one to several satellites.
The orbital transfer business device 44 is an orbital transfer business computer that issues space object intrusion warnings to satellites.
The debris removal business device 45 is a computer of a debris removal business operator that carries out a business of collecting debris. The debris removal business device 45 is used for managing the debris removal satellites by the debris removal business operator that removes space objects.
The rocket launch business device 46 is a computer of a rocket launch business operator that carries out the rocket launch business.
The SSA business device 47 is a computer of an SSA business operator that performs the SSA business, i.e., the space situation monitoring business.

The business device 40 may be any other device that collects information about space objects such as artificial satellites or debris and provides the collected information to the space traffic management system 800. In addition, if the space traffic management device 200 is mounted on the SSA's public server, the space traffic management device 200 may be configured to function as the SSA's public server.

The space traffic management device 200 includes a processor 910, as well as other hardware such as a memory 921, an auxiliary storage device 922, an input interface 930, an output interface 940, and a communication device 950. The processor 910 is connected to the other hardware via signal lines and controls the other hardware.

The space traffic management device 200 includes, as examples of functional elements, a space traffic management unit 120 and a memory unit 140. The memory unit 140 stores rule information 515 and dense area identification information 525.

The functions of the space traffic management unit 120 are realized by software. The storage unit 140 is provided in the memory 921. Alternatively, the storage unit 140 may be provided in the auxiliary storage device 922. The storage unit 140 may also be provided separately in the memory 921 and the auxiliary storage device 922.

The space traffic management unit 120, for example, manages the space object 60 according to the rule information 515. Alternatively, the space traffic management unit 120 uses the dense area identification information 525 to manage the space object 60 according to the rule information 515.

The processor 910 is a device that executes a space traffic management program. The space traffic management program is a program that realizes the functions of each component of the space traffic management device 200 and the space traffic management system 800.

The hardware of the space traffic management device 200 is similar to the hardware of the satellite constellation forming system 100 described in Figure 6.

The space traffic management program is loaded into the processor 910 and executed by the processor 910. The memory 921 stores not only the space traffic management program but also an OS (Operating System). The processor 910 executes the space traffic management program while executing the OS. The space traffic management program and the OS may be stored in the auxiliary storage device 922. The space traffic management program and the OS stored in the auxiliary storage device 922 are loaded into the memory 921 and executed by the processor 910. Note that part or all of the space traffic management program may be incorporated into the OS.

The space traffic management device 200 may include multiple processors that replace the processor 910. These multiple processors share the task of executing the program. Each processor is a device that executes a program, just like the processor 910.

The "parts" of each part of the space traffic control device may be read as "processing,""procedure,""means,""stage," or "step." In addition, the "processing" of the passage determination process, the alarm generation process, and the alarm notification process may be read as "program,""programproduct," or "computer-readable recording medium on which a program is recorded.""Processing,""procedure,""means,""stage," or "step" may be read as interchangeable with one another.
The space traffic management program causes a computer to execute each process, procedure, means, stage, or step of the space traffic management system, where the "part" of each part is interpreted as a "process,""procedure,""means,""stage," or "process." Also, the space traffic management method is a method carried out by space traffic management device 200 executing the space traffic management program.
The space traffic management program may be provided in a form stored in a computer-readable recording medium. Also, each program may be provided as a program product.

<Functional Overview of the Space Traffic Management System of the Present Embodiment>
Sun-synchronous orbits are commonly used in Earth observation, and are particularly densely populated with the following areas:
- The region in the vicinity of sun-synchronous orbit LST10:30, with an orbital altitude of 500 km or more and 1000 km or less.
- Sun-synchronous orbit, near LST13:30, in the region with an orbital altitude of 500km to 1000km.
- Sun-synchronous orbit near LST06:00, in the region with an orbital altitude of 500km to 1000km.
- Sun-synchronous orbit near LST 18:00, in the region with an orbital altitude of 500 km to 1000 km.

Since the orbital inclination angle of a sun-synchronous orbit is close to 90 degrees, satellites flying at the same orbital altitude have their orbital planes intersecting at the polar regions, increasing the risk of collision.
Therefore, if a rule for STM (Space Traffic Management) is made that satellites in orbital planes with different normal vectors use different orbital altitudes and the orbital intersections are eliminated, the collision probability during regular operations will be zero, and the collision risk will be eliminated. In reality, collision risk does occur during non-regular operations such as orbit insertion and deorbit, but if the collision probability during regular operations is zero, the risk will be greatly reduced.

Another method to avoid collisions is to shift the timing of polar crossings through artificial control, but since many operators in many countries operate satellites in sun-synchronous orbit, there remains a risk of collisions if they do not cooperate with each other.
There is also the issue that if an unforeseen accident, such as a debris collision, occurs and human control becomes impossible, there is a high risk of collision.
Therefore, if the collision probability during normal operation is zero, it has the effect of being able to avoid collision accidents even if human control becomes impossible.

Specifically, as shown in Figures 29 and 30, the space traffic management system 800 according to this embodiment executes a space traffic management process for managing space traffic of space objects 60 using information such as rule information 515 and dense area identification information 525. That is, in the space traffic management system 800, multiple space traffic management devices 200 manage the traffic of space objects 60 using rule information 515 and dense area identification information 525 that are common to the multiple space traffic management devices 200. The rule information 515 is also referred to as space traffic management rules 501.

<Space traffic management processing example 1>
The space traffic management unit 120 performs space traffic management processing for the space object 60 so that satellites in orbital planes with different normal vectors adopt different orbital altitudes.

Specifically, the rule information 515 includes information that indicates a rule that satellites in orbital planes with different normal vectors adopt different orbital altitudes.
The space traffic management unit 120 manages the space object 60 in accordance with the rule information 515 .

According to space traffic management processing example 1, satellites in orbital planes with different normal vectors adopt different orbital altitudes, which has the effect of eliminating the probability of collisions in polar regions and eliminating the risk of collisions during normal operations.

<Space traffic management processing example 2>
The space traffic management unit 120 performs space traffic management processing for the space object 60 so that multiple satellites with the same normal vector and flying at the same orbital altitude fly while maintaining a relative phase angle that results in approximately equal spacing within the orbital plane.

Specifically, the rule information 515 contains information that represents a rule that multiple satellites that have the same normal vector and fly at the same orbital altitude fly while maintaining a relative phase angle that results in approximately equal spacing within the orbital plane.
The space traffic management unit 120 manages the space object 60 in accordance with the rule information 515 .

FIG. 31 is a diagram showing a satellite arrangement in an orbital plane in a comparative example of the space traffic management processing example 2.
FIG. 32 is a diagram showing a satellite arrangement in an orbital plane in example 2 of the space traffic management processing according to this embodiment.
FIG. 33 is a diagram showing multiple orbital planes with the same normal vector but different orbital altitudes.

As shown in Figures 31 and 32, multiple satellites flying at the same orbital altitude in the same orbital plane can avoid collisions by flying in sync. However, if multiple satellites managed by different operators fly without managing the relative phase angles, there is a risk of collision.
According to the space traffic management process example 2, a plurality of satellites flying in the same orbital plane are identified using the space traffic management rules 501, and the plurality of satellites flying at the same orbital altitude fly while maintaining a relative phase angle that results in a roughly uniform arrangement in the orbital plane, thereby having the effect of avoiding collisions.

<Space traffic management processing example 3>
The dense area identification information 525 is information for identifying the following areas as dense areas.
- The region in the vicinity of sun-synchronous orbit LST10:30, with an orbital altitude of 500 km or more and 1000 km or less.
- Sun-synchronous orbit, near LST13:30, in the region with an orbital altitude of 500km to 1000km.
- Sun-synchronous orbit near LST06:00, in the region with an orbital altitude of 500km to 1000km.
- Sun-synchronous orbit near LST 18:00, in the region with an orbital altitude of 500 km to 1000 km.
- Areas above 80 degrees north latitude and with orbital altitudes between 500km and 1000km.
- Areas above 80 degrees south latitude and with orbital altitudes between 500km and 1000km.
The orbits around LST10:30 and LST13:30 are frequently used by optical satellites or various earth observation satellites known as the A-Train. The orbits around LST06:00 and LST18:00 are frequently used by radar satellites equipped with synthetic aperture radar.

The rule information 515 includes space traffic management rules 501 that indicate rules for operators who manage satellites flying in congested areas to disclose satellite information.
The space traffic management unit 120 realizes a means for operators managing satellites flying in the same orbital plane to exchange information on flight safety measures using the dense area identification information 525 and the rule information 515. The flight safety measure information exchanged here is information on the orbit altitude for each orbital plane to ensure flight safety.

In the space traffic management processing example 3, the space traffic management device 200 has the congested area identification information 525. The space traffic management device 200 also has space traffic management rules 501 by which operators who manage satellites flying in the congested area disclose satellite information, and a means by which operators who manage satellites flying in the same orbital plane can exchange information about flight safety measures.
Since it is dangerous for multiple operators to fly satellites in this orbit without control, satellite orbit information is made public as a traffic rule, and an environment is developed in which measures to ensure flight safety can be coordinated. Therefore, according to the space traffic management processing example 3, it is possible to avoid collisions.
As a means for exchanging information about flight safety measures, the space traffic management system 800 may be provided with a chat function on its portal, or a message may be sent to host a coordination meeting.

<Space traffic management processing example 4>
The space traffic management unit 120 uses the dense area identification information 525 to capture the space object 60 before it enters any of the dense areas during the process of leaving the orbit and re-entering the atmosphere, thereby achieving collision avoidance operation during orbit descent. Such a method of achieving collision avoidance operation during orbit descent is called an orbit descent collision avoidance operation method.
A specific example of the crowded area is similar to that described in Example 3 of the space traffic management process.

FIG. 34 is a diagram showing the intrusion of a high-altitude mega-constellation satellite into a crowded area (dangerous area) during the process of satellite orbit descent.
FIG. 35 is a diagram showing a space traffic management process for avoiding intrusion into a crowded area during a satellite orbit descent process according to this embodiment.

Specifically, the rule information 515 includes space traffic management rules 501 that represent rules for capturing the space object 60 before it enters any of the crowded regions during the process of leaving the orbit and re-entering the atmosphere, thereby realizing collision avoidance during orbit descent. The collision avoidance during orbit descent is also called active de-orbit operation.
The space traffic management unit 120 uses the dense area identification information 525 and the rule information 515 to capture the space object 60 before it enters any of the dense areas during the process of leaving orbit and re-entering the atmosphere, thereby achieving collision avoidance operations during orbit descent.

A specific explanation will be given using FIG.
(1) The space traffic control device 200 of the mega constellation business device 41 predicts that a high-altitude mega constellation satellite will become a malfunctioning satellite and invade a congested area (dangerous area). This intrusion prediction information is shared by all the space traffic control devices 200 of the space traffic management system 800 via communication lines.
(2) The space traffic management device 200 of the debris removal business device 45 captures the space object 60 before it enters any of the crowded areas based on the rule information 515, thereby realizing a collision avoidance operation during orbital descent. Specifically, a rapid-response debris removal satellite is launched.
(3) A rapid-response debris removal satellite will capture and combine with a malfunctioning satellite, and then re-enter the atmosphere while avoiding congested areas. This will allow for collision avoidance during orbital descent.

Embodiment 13.
In this embodiment, a description will be given mainly of differences from or additions to the embodiments 1 to 12. Note that the same reference numerals are used for configurations similar to those in the embodiments 1 to 12, and descriptions thereof may be omitted.
In particular, in this embodiment, a variation of the debris removal business device 45 described above will be confirmed.

FIG. 36 is a diagram showing an example of the configuration of a debris removal satellite 31 according to this embodiment.
The debris removal satellite 31 includes a capture device 36 that captures space objects such as debris, a propulsion device 33, a satellite control device 310 that is an orbit control device, and a satellite communication device 32 that is a communication device. The satellite control device 310 is an orbit control device that controls the orbit of the satellite 30 by controlling the propulsion device 33 and the attitude control device 34 in accordance with various commands transmitted from the ground facility 500.

The debris removal satellite 31 captures debris in response to control commands from the debris removal control device, and performs active control operation during orbit descent to avoid areas with a high risk of collision with space objects during the deorbit process up until re-entry into the atmosphere. Active control operation during orbit descent is also called active deorbit operation.
The debris removal control device may be mounted on the ground facility 500. Also, the debris removal control device may be mounted on the debris removal business device 45, or may be mounted on another device that communicates with the debris removal business device 45. Also, the debris removal business device 45 may be configured to include the ground facility 500.

<Example 1 of debris removal business equipment>
The debris removal business equipment 45 uses the debris removal satellite 31 to capture the space object before it enters the satellite-dense area (also called the satellite-congested area) described below, and performs collision avoidance operations during orbital descent.
- The region in the vicinity of sun-synchronous orbit LST10:30, with an orbital altitude of 500 km or more and 1000 km or less.
- Sun-synchronous orbit, near LST13:30, in the region with an orbital altitude of 500km to 1000km.
- Sun-synchronous orbit near LST06:00, in the region with an orbital altitude of 500km to 1000km.
- Sun-synchronous orbit near LST 18:00, in the region with an orbital altitude of 500 km to 1000 km.
- Areas above 80 degrees north latitude and with orbital altitudes between 500km and 1000km.
- Areas above 80 degrees south latitude and with orbital altitudes between 500km and 1000km.

<Example 2 of debris removal equipment>
The debris removal satellite 31 is a responsive satellite that is prepared for launch and waits on the ground.
The debris removal business device 45 launches a debris removal satellite 31 into the predicted orbit of the space object after it is predicted that the space object will enter an area densely populated with satellites, and the debris removal satellite 31 captures the space object and performs collision avoidance operations during the orbital descent.
The debris removal business equipment 45 may be a ground facility 500 .

<Example 3 of debris removal business equipment>
When analytical predictions reveal that a space object will pass through one of the satellite-dense areas described in Example 1 of the Debris Removal Business Device during its process of leaving orbit and re-entering the atmosphere, the debris removal business device 45 performs the following control on the debris removal satellite 31.
The debris removal business equipment 45 sends commands to the orbit control device equipped on the debris removal satellite to increase or decrease the orbital altitude by accelerating or decelerating the satellite speed, or to change the orbital inclination by applying acceleration out of the orbital plane by jetting the thrusters in a direction approximately perpendicular to the satellite's direction of travel, thereby performing collision avoidance operations during orbit descent to avoid the risk of collision by shifting the timing of passing through a congested orbit or the orbital plane.

<Example 4 of debris removal business equipment>
The debris removal business equipment 45 may be a ground facility 500 .
The ground equipment 500 is used for operational control of the debris removal satellite 31 by debris removal operators who remove space objects using the debris removal satellite 31.
The debris removal satellite 31 comprises a capture device 36 that restrains a space object in six degrees of freedom, and a propulsion device 33 .
The ground facility 500 includes a means for analyzing the position of the center of gravity of the debris removal satellite 31 in a state in which the space object has been captured. Then, the ground facility 500 transmits a command to the orbit control device included in the debris removal satellite 31, and controls the orbit control device so that the injection vector of the propulsion device 33 passes through the center of gravity in the captured state.

As described above, the debris removal business equipment 45 may be the ground equipment 500. The debris removal business equipment 45 may also be configured to include the ground equipment 500. The ground equipment 500 may also be configured to include the debris removal business equipment 45.

<Example 5 of debris removal business equipment>
The debris removal business apparatus 45 also includes a space traffic control device 200 that is compatible with the space traffic control devices included in a number of business apparatuses that manage space objects.
The debris removal business equipment 45 is connected to a space traffic management system, which connects space traffic control devices equipped in multiple business equipment with each other via communication lines, via a space traffic control device 200.

FIG. 37 is a diagram showing a detailed configuration example of the space traffic management device 200 of the debris removal business device 45 according to this embodiment.
The space traffic management device 200 includes all or some of a space information recorder 101 , a danger warning device 102 , a danger analysis device 103 , a danger avoidance action support device 104 , danger avoidance action implementation plan information 105 , and a security management device 106 .
The space information recorder 101 records orbital information of space objects.
The danger warning device 102 provides an indication that a space object is approaching a danger area.
The risk analysis device 103 analyzes the time and the position on the orbit when a risk is predicted.
The danger avoidance action support device 104 supports the planning of danger avoidance actions.
The danger avoidance action implementation plan information 105 is information for implementing a danger avoidance action.
The security management device 106 prevents information from being tampered with. The security management device 106 manages security management information for preventing information from being tampered with.

For example, the space traffic management device 200 realizes the following functions.
A danger warning device 102 obtains prediction information regarding the approach or collision between space object A and space object B.
A danger analysis device 103 acquires orbital information of space object A and orbital information of space object B from the space information recorder 101, and analyzes the time and orbital position when danger is predicted.
Then, the space traffic control device 200 executes danger avoidance actions using the debris removal satellite 31.

Furthermore, for example, the space traffic management device 200 realizes the following functions.
A danger warning device 102 obtains information regarding the intrusion of a space object into a danger area.
The danger analysis device 103 acquires the orbital information of the space object and the orbital information of multiple space objects flying in the danger area from the space information recorder 101, and analyzes the time and orbital position when danger is predicted.
The danger avoidance action support device 104 coordinates between businesses involved in danger avoidance and creates danger avoidance action implementation plan information 105.
Then, the space traffic control device 200 executes danger avoidance actions using the debris removal satellite 31.

The debris removal business device according to this embodiment captures a space object that has left orbit before it enters a satellite-dense area (also called a satellite-congested area) and performs collision avoidance operations during orbital descent. Therefore, the debris removal business device according to this embodiment has the effect of avoiding the risk of collision in satellite constellations.

Embodiment 14.
In this embodiment, differences from or additions to the embodiments 1 to 13 will be mainly described. Note that the same reference numerals are used to designate configurations similar to those in the embodiments 1 to 13, and descriptions thereof may be omitted.
In particular, in this embodiment, variations of the megaconstellation business device 41 described above will be confirmed.

<Example 1 of Mega Constellation Business Equipment>
As described above, the megaconstellation business device 41 includes a space traffic management device 200 .
The megaconstellation business equipment 41 is equipped with a space traffic management unit 120 that manages a group of satellites so that multiple satellites that have the same normal vector and fly at the same orbital altitude fly while maintaining a relative phase angle that results in approximately equal spacing within the orbital plane.

Alternatively, the megaconstellation business device 41 includes a space traffic management unit 120 that manages the satellite group so that satellites in orbital planes with different normal vectors adopt different orbital altitudes.

<Example 2 of Mega Constellation Business Equipment>
As described above, the megaconstellation business device 41 is equipped with the satellite constellation forming system 100 described above.
The mega-constellation business device 41 includes a satellite constellation forming unit 11 that forms a satellite constellation having a plurality of orbital planes in which a plurality of satellites fly at the same nominal orbital altitude in each orbital plane. The satellite constellation forming unit 11 continues to provide services while avoiding collisions by controlling the orbital altitudes of the group of satellites flying in an area where a plurality of orbital planes intersect and controlling the passing timing.

Alternatively, the mega-constellation business device 41 includes a satellite constellation forming unit 11 that, after a collision with a space object in orbital descent, a rocket in the middle of launch, a satellite in orbital transfer, or debris is predicted, continues to provide services while avoiding collisions by controlling the orbits of the satellite group and the timing of their passage.

<Example 3 of Mega Constellation Business Equipment>
The megaconstellation business equipment 41 includes a space traffic management unit 120 that performs collision avoidance operations for satellites during orbital descent before the satellites enter the following satellite-dense area (also called satellite congestion area).
- The region in the vicinity of sun-synchronous orbit LST10:30, with an orbital altitude of 500 km or more and 1000 km or less.
- Sun-synchronous orbit, near LST13:30, in the region with an orbital altitude of 500km to 1000km.
- Sun-synchronous orbit near LST06:00, in the region with an orbital altitude of 500km to 1000km.
- Sun-synchronous orbit near LST 18:00, in the region with an orbital altitude of 500 km to 1000 km.
- Areas above 80 degrees north latitude and with orbital altitudes between 500km and 1000km.
- Areas above 80 degrees south latitude and with orbital altitudes between 500km and 1000km.

<Example 4 of Mega Constellation Business Equipment>
The megaconstellation business equipment 41 includes ground equipment 500 as described above.
The ground facility 500 includes a communication device that transmits and receives signals for tracking and controlling the satellites that make up the satellite constellation, an orbit control command transmission unit that transmits an orbit control command, and an analysis and prediction unit that analyzes and predicts the passing orbit of the satellite after receiving a deorbit command. The ground facility 500 transmits the orbit control command to deorbit the satellite that has reached the end of its design life by operating a propulsion device equipped on the satellite.
When the analysis prediction unit determines that the satellite will pass through the orbital plane of the satellite constellation, the orbit control command transmission unit performs a collision avoidance operation during orbit descent to avoid a collision risk, using an orbit control device equipped in the satellite. Specifically, the orbit control command transmission unit transmits the orbit control command to perform a collision avoidance operation during orbit descent to avoid a collision risk by shifting the timing of passing through a congested orbit or the orbital plane. The orbit control command performs a collision avoidance operation during orbit descent to avoid a collision risk by shifting the timing of passing through a congested orbit or the orbital plane, by increasing or decreasing the orbital altitude by increasing or decreasing the satellite speed, or by changing the orbital inclination angle by applying acceleration in an out-of-plane direction of the orbital plane by thrusting the thruster in a direction approximately perpendicular to the satellite traveling direction.

<Example 5 of Mega Constellation Business Equipment>
The megaconstellation business device 41 includes the space traffic management device 200 as described above.
The space traffic management device 200 includes dense area identification information that identifies the above-mentioned satellite dense area (also called satellite congested area) as a dense area. The space traffic management device 200 also includes rule information that is a space traffic management rule that represents the rule for operators who manage satellites flying in the dense area to disclose satellite information. The space traffic management unit 120 uses the dense area identification information and the rule information to realize a means for operators who manage satellites flying in the same orbital plane to exchange information about flight safety measures. The flight safety measure information exchanged here is information about the orbital altitude for each orbital plane to ensure flight safety.

<Example 6 of Mega Constellation Business Equipment>
FIG. 38 is a diagram showing an example of the configuration of a megaconstellation business device 41 according to this embodiment.
FIG. 39 is a diagram showing a detailed configuration example of the space traffic management device 200 of the megaconstellation business device 41 according to this embodiment.

The megaconstellation business equipment 41 includes the space traffic management equipment 200 as described above.
The space traffic management device 200 also includes all or part of a space information recorder 101, rule information which is space traffic management rules representing the rules for multiple operators to disclose satellite information, a danger warning device 102, a danger analysis device 103, a danger avoidance action support device 104, danger avoidance action implementation plan information 105, and a security management device 106.

For example, the rule information includes rule information that describes a rule that multiple satellites that have the same normal vector and fly at the same orbital altitude fly while maintaining a relative phase angle that results in approximately equal spacing within the orbital plane, and rule information that states that satellites in orbital planes with different normal vectors adopt different orbital altitudes.

Also, for example, the rule information includes rule information for operating a satellite constituting a mega-constellation satellite group in a collision avoidance manner during its orbital descent before the satellite enters any of the above-mentioned satellite-dense regions (also called satellite congestion regions) during the process of the satellite leaving its orbit and re-entering the atmosphere.

FIG. 40 is a diagram showing an example of orbit forecast information according to the present embodiment.
The above-mentioned space traffic management device includes trajectory forecast information in which predicted values of the trajectory of a space object are set.
The orbit forecast information includes satellite orbit forecast information and debris orbit forecast information. The satellite orbit forecast information includes forecast values of satellite orbits. The debris orbit forecast information includes forecast values of debris orbits.

The orbit forecast information includes, for example, the space object ID, forecast epoch, forecast orbital elements, and forecast error.

The space object ID is an identifier that identifies a space object. In FIG. 8, a satellite ID and a debris ID are set as the space object ID. Specifically, space objects are objects such as rockets launched into space, flying vehicles, artificial satellites, space stations, debris removal satellites, planetary exploration spacecraft, and satellites or rockets that have become debris after completing a mission.

A forecast epoch is an epoch that is predicted for the orbit of each of a plurality of space objects.
The forecast orbital elements are orbital elements that specify the orbit of each of the multiple space objects. The forecast orbital elements are orbital elements that are predicted for the orbit of each of the multiple space objects. In Fig. 8, six Keplerian orbit elements are set as the forecast orbital elements.

The forecast error is the error predicted for each orbit of multiple space objects. The forecast error includes a heading error, a perpendicular error, and the basis for the error. In this way, the forecast error explicitly indicates the amount of error contained in the actual value along with the basis. The basis for the amount of error includes some or all of the measurement means, the contents of the data processing carried out as a means of improving the accuracy of position coordinate information, and the results of statistical evaluation of past data.

In the orbit forecast information, a forecast origin and forecast orbital elements are set for the space object. The forecast origin and the forecast orbital elements can be used to determine the time and position coordinates of the space object in the near future. For example, the time and position coordinates of the space object in the near future may be set in the orbit forecast information.
In this way, the orbital forecast information includes orbital information of a space object, including epoch and orbital elements, or time and position coordinates, and explicitly indicates the near-future forecast values of the space object.

The above-mentioned space traffic management device also includes trajectory performance information in which actual values of the trajectory of the space object are set. The configuration of the trajectory performance information is the same as that of the trajectory forecast information.

In the above first to fourteenth embodiments, each part of the satellite constellation forming system and the space traffic management system has been described as an independent functional block. However, the configuration of the satellite constellation forming system and the space traffic management system does not have to be as in the above-mentioned embodiments. The functional blocks of the satellite constellation forming system and the space traffic management system may have any configuration as long as they can realize the functions described in the above-mentioned embodiments. Furthermore, the satellite constellation forming system and the space traffic management system may be a system composed of one device or multiple devices.
In addition, a combination of multiple parts of the first to fourteenth embodiments may be implemented. Alternatively, one part of these embodiments may be implemented. In addition, any combination of these embodiments may be implemented, either as a whole or in part.
That is, in the first to fourteenth embodiments, any combination of the embodiments is possible, or any component of each embodiment can be modified, or any component of each embodiment can be omitted.

The above-described embodiment is essentially a preferred example, and is not intended to limit the scope of the present invention, the scope of the application of the present invention, or the scope of use of the present invention. The above-described embodiment can be modified in various ways as necessary.

11, 11b Satellite constellation formation unit, 20 Satellite constellation, 21 Orbital plane, 30 Satellite, 31 Debris removal satellite, 32 Satellite communication device, 33 Propulsion device, 34 Attitude control device, 35 Power supply device, 36 Capture device, 40 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 Orbital control command, 52 Capture command, 60 Space object, 70 Earth, 100 Satellite constellation formation system, 200 Space traffic management device, 110 Satellite constellation formation unit, 120 Space traffic management unit, 140 Memory unit, 300 Satellite group, 310 Satellite control device, 500 Ground equipment, 501 Space traffic management rules, 510 Orbit control command transmission unit, 515 rule information, 525 dense area identification information, 520 analysis prediction unit, 600 satellite constellation formation system, 800 space traffic management system, 910 processor, 921 memory, 922 auxiliary storage device, 930 input interface, 940 output interface, 950 communication device, 101 space information recorder, 102 danger warning device, 103 danger analysis device, 104 danger avoidance action support device, 105 danger avoidance action implementation plan information, 106 security management device.

Claims (1)

A debris removal business device that includes a debris removal satellite and ground equipment, and removes space objects that constitute a mega-constellation that are at risk of colliding with satellites flying at lower orbital altitudes when deorbiting at the end of their life or when a malfunction occurs,
The debris removal satellite,
A responsive satellite that is prepared for launch and stands by on the ground, the satellite comprising a capture device that captures the space object by constraining it in six degrees of freedom , a propulsion device, an orbit control device, and a communication device;
During the process of the space object leaving its orbit and re-entering the atmosphere,
A region in which the orbit altitude is between 500km and 1000km in the vicinity of 10:30am Local Sun Time (LST) in a sun-synchronous orbit;
A region in the vicinity of the sun-synchronous orbit LST13:30 with an orbit altitude of 500 km to 1000 km.
A region in the vicinity of the sun-synchronous orbit LST06:00 with an orbit altitude of 500km to 1000km.
A region in the vicinity of the sun-synchronous orbit LST 18:00 with an orbit altitude of 500 km or more and 1000 km or less;
An area above 80 degrees north latitude with an orbital altitude of 500km to 1000km,
After it is predicted that the space object will enter a region having a latitude of 80 degrees south or more and an orbital altitude of 500 km or more and 1000 km or less, launching the debris removal satellite into the predicted orbit of the space object,
The ground equipment includes:
A debris removal business device comprising a means for analyzing the position of the center of gravity of the debris removal satellite when it has captured the space object, and sending a command to an orbit control device equipped on the debris removal satellite to operate and control the orbit control device so that the jet vector of the propulsion device passes through the center of gravity in the captured state, thereby performing collision avoidance operations during orbit descent to avoid the risk of collision by shifting the timing of passing through a congested orbit or the orbital plane by increasing or decreasing the satellite speed to raise or lower the orbital altitude, or by changing the orbital inclination angle by applying acceleration in an out-of-plane direction of the orbital plane by jetting the propulsion device in a direction approximately perpendicular to the satellite 's direction of travel.

Images