JP7621533B2 - Collision avoidance method and ground equipment - Google Patents

Description

This disclosure relates to technology for avoiding collisions between satellites in a satellite constellation and flying objects.

A satellite constellation consisting of about 1,600 artificial satellites is planned to be constructed at an altitude of about 1,100 kilometers. A satellite constellation consisting of about 1,600 artificial satellites is planned to be constructed at an altitude of about 550 kilometers.
It is expected that three satellite constellations with different orbital altitudes and inclinations will be constructed at an altitude of about 340 km. Each satellite constellation will consist of about 2,500 satellites. In other words, the satellite constellation will consist of about 7,500 satellites in total.
These satellite constellations are reported to be capable of automatic collision avoidance operations.

Assume that another satellite constellation is constructed at an altitude of about 1200 kilometers.
If a satellite in this constellation is de-orbited by PMD or ADR, there is a risk that the satellite will collide with thousands of other satellites at lower altitudes.
PMD is an abbreviation for Post Mission Disposal.
ADR is an abbreviation for Active Debris Removal.

Let's assume that active de-orbit operations are performed, such as adjusting the timing of the de-orbiting satellite to pass at an altitude where several thousand satellites exist, in an attempt to avoid a collision. Let's also assume that the other satellite automatically activates its avoidance operation function. In that case, there is a risk of a collision occurring, as both satellites will behave differently from their avoidance predictions.

If the rocket is launched, there is a risk that it will collide with a satellite in a satellite constellation built at an altitude of 340 kilometers or 550 kilometers.

Patent Document 1 discloses a technique for bringing two non-geostationary satellites closer to each other while avoiding collision between the two non-geostationary satellites whose satellite orbits intersect with each other.
This technology is not intended to avoid collisions between each satellite in a satellite constellation and a flying object.

JP 2006-117180 A Special Publication No. 2014-520724 Special table 2017-526280 publication International Publication No. 2018/222796 US Patent Application Publication No. 2013/0024102

The purpose of this disclosure is to make it possible to avoid collisions between a rocket and each satellite in a satellite constellation.

The collision avoidance method of the present disclosure is performed by a satellite constellation and a ground facility on the ground that controls the satellite constellation.
When a rocket is scheduled to be launched into space, the ground facility transmits a collision avoidance command to each artificial satellite of the satellite constellation to instruct the satellite to take an avoidance action to avoid a collision with the rocket;
Each satellite of the satellite constellation receives the collision avoidance command transmitted by the ground facility and takes the avoidance action instructed by the received collision avoidance command.

This disclosure makes it possible to avoid collisions between a rocket and each satellite in a satellite constellation.

FIG. 1 is a configuration diagram of a collision avoidance system 100A according to a first embodiment. FIG. 2 is a configuration diagram of an artificial satellite 110 according to the first embodiment. FIG. 2 is a configuration diagram of a constellation control device 200 according to the first embodiment. FIG. 4 is a configuration diagram of a storage unit 290 according to the first embodiment. 4 is a flowchart of a collision avoidance method in the first embodiment. FIG. 11 is a configuration diagram of a collision avoidance system 100B according to a second embodiment. 13 is a flowchart of a collision avoidance method in the second embodiment. FIG. 11 is a configuration diagram of a collision avoidance system 100C according to a third embodiment. FIG. 11 is a diagram showing the configuration of a rocket 130 in embodiment 3. FIG. 11 is a configuration diagram of a launch control device 300 in embodiment 3. FIG. 13 is a configuration diagram of a storage unit 390 according to the third embodiment. 13 is a flowchart of a collision avoidance method in the third embodiment. FIG. 13 is a diagram showing an image of a satellite flying in the third embodiment. FIG. 13 is a configuration diagram of a collision avoidance system 100D according to a fourth embodiment. FIG. 13 is a configuration diagram of a constellation control device 200 according to a fourth embodiment. FIG. 13 is a configuration diagram of a storage unit 290 according to the fourth embodiment. 13 is a flowchart of a collision avoidance method in the fourth embodiment. FIG. 13 is a configuration diagram of a collision avoidance system 100E according to a fifth embodiment. FIG. 23 is a configuration diagram of a storage unit 290 according to the fifth embodiment. 13 is a flowchart of a collision avoidance method in the fifth embodiment. FIG. 13 is a diagram showing an example of a geostationary transfer orbit in embodiment 5. FIG. 13 is a diagram showing an example of a geostationary transfer orbit in embodiment 5. FIG. 23 is a configuration diagram of a collision avoidance system 100F in a sixth embodiment. FIG. 23 is a diagram showing the configuration of a rocket 130 in embodiment 6. FIG. 23 is a configuration diagram of a launch control device 300 in embodiment 6. FIG. 23 is a configuration diagram of a storage unit 390 according to the sixth embodiment. 23 is a flowchart of a collision avoidance method in the sixth embodiment. FIG. 23 is a configuration diagram of a collision avoidance system 100G in a seventh embodiment. FIG. 23 is a diagram showing the relationship between flight speed and orbit altitude in the seventh embodiment. FIG. 23 is a configuration diagram of a collision avoidance system 100H according to an eighth embodiment. FIG. 23 is a configuration diagram of a constellation control device 200 according to an eighth embodiment. FIG. 23 is a configuration diagram of a storage unit 290 in the eighth embodiment. 20 is a flowchart of a collision avoidance method in the eighth embodiment.

In the embodiments and drawings, the same or corresponding elements are given the same reference numerals. Explanations of elements given the same reference numerals as elements described above will be omitted or simplified as appropriate. Arrows in the drawings primarily indicate data flow or processing flow.

Embodiment 1.
A method for avoiding collisions between a deorbiting satellite and other satellites will be described with reference to Figs. 1 to 5.

***Configuration Description***
The configuration of a collision avoidance system 100A will be described with reference to FIG.
The collision avoidance system 100A includes a first satellite constellation 101, a second satellite constellation 102, and a ground facility 180.

The first satellite constellation 101 is a satellite constellation constructed at an orbital altitude higher than the orbital altitude of the second satellite constellation 102 .
The first satellite constellation 101 is made up of a plurality of artificial satellites 110 .
The artificial satellite 110 that is scheduled to deorbit and fall from the orbit of the first satellite constellation 101 is referred to as a deorbiting satellite 110X.

The second satellite constellation 102 is a satellite constellation constructed at an orbital altitude lower than that of the first satellite constellation 101.
The second satellite constellation 102 is made up of a plurality of satellites 120 .

Ground facility 180 is a facility located on Earth 109 that controls first satellite constellation 101 on the ground.
The ground equipment 180 includes a communication device 181 and a constellation control device 200 .

In the collision avoidance system 100A, a collision avoidance method is performed by the first satellite constellation 101 (its deorbiting satellite 110X) and the ground facility 180.
This collision avoidance method avoids collision of the deorbiting satellite 110X with each satellite 120 of the second satellite constellation 102.

The configuration of the artificial satellite 110 will be described with reference to FIG.
The artificial satellite 110 includes a monitoring device 111, a satellite control device 112, a communication device 113, a propulsion device 114, an attitude control device 115, and a power supply device 116.
The monitoring device 111 is a device for monitoring a target area on the Earth 109. For example, the monitoring device 111 is a visible optical sensor, an infrared optical sensor, or a synthetic aperture radar (SAR). The monitoring device 111 generates monitoring data. The monitoring data is data corresponding to an image showing the target area on the Earth.
The satellite control device 112 is a computer that controls the artificial satellite 110. Specifically, the satellite control device 112 controls the monitoring device 111, the propulsion device 114, and the attitude control device 115 in accordance with various commands transmitted from the ground facility 180.
The communication device 113 is a device that communicates with the ground equipment 180. Specifically, the communication device 113 transmits monitoring data to the ground equipment 180. In addition, the communication device 113 receives various commands transmitted from the ground equipment 180.
The propulsion device 114 is a device that provides thrust to the artificial satellite 110 and changes the speed of the artificial satellite 110. Specifically, the propulsion device 114 is an electric propulsion device. For example, the propulsion device 114 is an ion engine or a Hall thruster.
The attitude control device 115 is a device for controlling attitude elements such as the attitude of the artificial satellite 110, the angular velocity of the artificial satellite 110, and the line of sight of the monitoring device 111. The attitude control device 115 changes each attitude element to a desired direction. Alternatively, the attitude control device 115 maintains each attitude element in a desired direction. The attitude control device 115 includes an attitude sensor, an actuator, and a controller. The attitude sensor is a gyroscope, an earth sensor, a sun sensor, a star tracker, a thruster, a magnetic sensor, or the like. The actuator is an attitude control thruster, a momentum wheel, a reaction wheel, a control moment gyro, or the like. The controller controls the actuator according to measurement data of the attitude sensor or various commands from the ground facility 180.
The power supply unit 116 includes a solar cell, a battery, a power control device, and the like, and supplies power to each device mounted on the satellite 110 .

The satellite control device 112 will now be described in more detail.
The satellite controller 112 includes processing circuitry.
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.
Dedicated hardware may be, for example, a single circuit, multiple circuits, a programmed processor, parallel programmed processors, an ASIC, an FPGA, or a combination of these.
ASIC is an abbreviation for Application Specific Integrated Circuit.
FPGA is an abbreviation for Field Programmable Gate Array.

The configuration of the constellation control device 200 will be described with reference to FIG.
The constellation control device 200 is a computer including hardware such as a processor 201, a memory 202, an auxiliary storage device 203, a communication interface 204, and an input/output interface 205. These pieces of hardware are connected to each other via signal lines.

The processor 201 is an IC that performs arithmetic processing and controls other hardware. For example, the processor 201 is a CPU, a DSP, or a GPU.
IC is an abbreviation for Integrated Circuit.
CPU is an abbreviation for Central Processing Unit.
DSP is an abbreviation for Digital Signal Processor.
GPU is an abbreviation for Graphics Processing Unit.

The memory 202 is a volatile or non-volatile storage device. The memory 202 is also called a primary storage device or a main memory. For example, the memory 202 is a RAM. Data stored in the memory 202 is saved in the secondary storage device 203 as necessary.
RAM is an abbreviation for Random Access Memory.

The auxiliary storage device 203 is a non-volatile storage device. For example, the auxiliary storage device 203 is a ROM, a HDD, or a flash memory. The data stored in the auxiliary storage device 203 is loaded into the memory 202 as needed.
ROM is an abbreviation for Read Only Memory.
HDD is an abbreviation for Hard Disk Drive.

The communication interface 204 is a port to which the communication device 181 is connected, and functions as a receiver and a transmitter.

The input/output interface 205 is a port to which an input device and an output device are connected. For example, the input/output interface 205 is a USB terminal, the input device is a keyboard and a mouse, and the output device is a display.
USB is an abbreviation for Universal Serial Bus.

The constellation control device 200 includes elements such as an orbit deviation detection unit 211, an avoidance action decision unit 212, and an avoidance action instruction unit 213. These elements are realized by software.

The auxiliary storage device 203 stores a collision avoidance program for causing the computer to function as an orbit deviation detection unit 211, an avoidance action decision unit 212, and an avoidance action instruction unit 213. The collision avoidance program is loaded into the memory 202 and executed by the processor 201.
The auxiliary storage device 203 further stores an OS. At least a part of the OS is loaded into the memory 202 and executed by the processor 201.
The processor 201 executes a collision avoidance program while executing the OS.
OS is an abbreviation for Operating System.

Input and output data for the collision avoidance program are stored in the memory unit 290 .
The memory 202 functions as the storage unit 290. However, a storage device such as the auxiliary storage device 203, a register in the processor 201, or a cache memory in the processor 201 may function as the storage unit 290 instead of the memory 202 or together with the memory 202.

The constellation control device 200 may include multiple processors that replace the processor 201. The multiple processors share the functions of the processor 201.

The collision avoidance program can be recorded (stored) in a computer-readable manner on a non-volatile recording medium such as an optical disk or flash memory.

The configuration of the storage unit 290 will be described with reference to FIG.
The memory unit 290 stores first satellite constellation data 291, second satellite constellation data 292, and the like.
The first satellite constellation data 291 is orbital data of the first satellite constellation 101 and includes orbital data of each artificial satellite 110 in the first satellite constellation 101 .
The second satellite constellation data 292 is orbital data for the second satellite constellation 102 and includes orbital data for each artificial satellite 120 in the second satellite constellation 102 .

*** Operation Description ***
The procedure of operation of the collision avoidance system 100A corresponds to a collision avoidance method.

The collision avoidance method will be described with reference to FIG.
Assume that there is a satellite 110 (deorbiting satellite 110X) in the first satellite constellation 101 that is scheduled to deorbit and fall.

Steps S111 to S113 are executed by the constellation control device 200 of the ground equipment 180.

In step S111, the orbit departure detection unit 211 detects, based on the first satellite constellation data 291, the artificial satellite 110 that is scheduled to de-orbit and fall.
The detected satellite 110 is a deorbiting satellite 110X.

For example, the de-orbit detection unit 211 detects the de-orbit satellite 110X as follows.
The first satellite constellation data 291 includes orbital data for each satellite 110 in the first satellite constellation 101. The orbital data for each satellite 110 includes a scheduled de-orbit date and time.
The orbit departure detection unit 211 detects the artificial satellites 110 whose scheduled orbit departure times fall within a detection target time period. The detection target time period is a future time period that is a detection target.
The detected satellite 110 is a deorbiting satellite 110X.

In step S112, the avoidance action determination unit 212 determines an avoidance action for the deorbiting satellite 110X based on the first satellite constellation data 291 and the second satellite constellation data 292.
This avoidance action is an action to avoid collision with each artificial satellite 110 of the second satellite constellation 102. For example, the avoidance action is determined based on the date and time of execution of deorbit, the direction of fall at the time of deorbit, and the speed of fall at the time of deorbit.

For example, the avoidance action determination unit 212 determines the avoidance action of the deorbiting satellite 110X as follows.
The second satellite constellation data 292 includes orbital data for each satellite 120 in the second satellite constellation 102 .
The avoidance action determination unit 212 receives as input the orbit data of the de-orbit satellite 110X during the de-orbit time period and the orbit data of each of the artificial satellites 120 during the de-orbit time period, and calculates an avoidance action determination algorithm, thereby determining an avoidance action.
The de-orbit window is the time period that includes the scheduled de-orbit date and time.
The avoidance action decision algorithm is an algorithm for deciding an avoidance action.

In step S113, the avoidance behavior instruction unit 213 generates a collision avoidance command. The collision avoidance command is a command for instructing an avoidance behavior.
The avoidance action instruction unit 213 then accesses the communication device 181 via the input/output interface 205 and uses the communication device 181 to transmit a collision avoidance command to the deorbital satellite 110X.

Steps S121 and S122 are performed by the deorbiting satellite 110X.

In step S121, the communication device 113 receives a collision avoidance command.

In step S122, the satellite controller 112 takes the avoidance action instructed by the collision avoidance command.
Specifically, the satellite controller 112 controls the thrusters 114 and the attitude controller 115 to take evasive action.

The operation of the second satellite constellation 102 will now be described.
There is a ground facility for controlling the second satellite constellation 102. This ground facility is referred to as the second ground facility.
The second ground facility, like the ground facility 180, includes a constellation control device and a communication device.
Even if the constellation control device of the second ground facility detects the deorbiting satellite 110X, it does not transmit a command to each artificial satellite 120 of the second satellite constellation 102 to instruct them to take action to avoid a collision with the deorbiting satellite 110X.
Therefore, each artificial satellite 120 of the second satellite constellation 102 will fly as planned without taking any action to avoid a collision with the deorbiting satellite 110X.

***Description of the embodiment***
In the first embodiment, a common database of satellite constellations is provided among multiple megaconstellation operators.
The satellites dropping from high altitudes will then carry out collision avoidance maneuvers, while the low-orbit satellite constellations will not carry out automatic collision avoidance maneuvers.

***Advantages of First Embodiment***
According to the first embodiment, it becomes possible to avoid collisions between the deorbiting satellite and each of the other satellites.

Many operators operate Earth observation satellites in low orbits at altitudes between 500 and 800 kilometers. In particular, the time around LST 10:30 is often used for optical satellites. Also, the time around LST 06:00 is often used for synthetic aperture radar satellites. For this reason, satellites are densely concentrated in the Dawndusk orbit around LST 10:30 or LST 06:00.
In the Dawndusk orbit, satellites passing nearby are closer to each other than in a geostationary orbit. In addition, some satellites, such as microsatellites, do not have propulsion systems. Therefore, in an uncontrolled situation where some satellites perform collision avoidance operations while others do not, there is a risk of accidental collisions occurring.
It is currently difficult for multiple operators to coordinate and take avoidance actions. Therefore, when satellite operators operating mega-constellations at high altitudes implement PMD or ADR, it is rational to avoid congested orbits and use active de-orbiting to avoid collisions.
The number of LSTs where Earth observation satellites are densely concentrated is limited, so in order to avoid congested orbits, it is reasonable to delay the timing of passing through the congested orbital plane.
Moreover, the first embodiment enables rational collision avoidance.

Embodiment 2.
A mode for avoiding collisions between the deorbiting satellite and each of the other satellites will be described with reference to Figs. 6 and 7, mainly focusing on the differences from the first embodiment.

***Configuration Description***
The configuration of the collision avoidance system 100B will be described with reference to FIG.
The collision avoidance system 100B includes a first satellite constellation 101, a second satellite constellation 102, and a ground facility 180.

The first satellite constellation 101 is a satellite constellation constructed at an orbital altitude lower than the orbital altitude of the second satellite constellation 102 .
The first satellite constellation 101 is made up of a plurality of artificial satellites 110 .

The second satellite constellation 102 is a satellite constellation constructed at an orbital altitude higher than that of the first satellite constellation 101.
The second satellite constellation 102 is made up of a plurality of satellites 120 .
The satellite 120 scheduled to deorbit and fall from the orbit of the second satellite constellation 102 is referred to as a deorbiting satellite 120X.

In the collision avoidance system 100B, a collision avoidance method is implemented by the first satellite constellation 101 and the ground facility 180.
This collision avoidance method avoids collision of the deorbiting satellite 120X with each of the satellites 110 of the first satellite constellation 101.

The configuration of the artificial satellite 110 is the same as that in embodiment 1 (see Figure 2).

The configuration of the constellation control device 200 is the same as that in embodiment 1 (see Figures 3 and 4).

*** Operation Description ***
The procedure of operation of the collision avoidance system 100B corresponds to a collision avoidance method.

The collision avoidance method will be described with reference to FIG.
Assume that there is a satellite 110 (deorbiting satellite 120X) in the second satellite constellation 102 that is scheduled to deorbit and fall.

Steps S211 to S213 are executed by the constellation control device 200 of the ground equipment 180.

In step S211, the de-orbit detection unit 211 detects, based on the second satellite constellation data 292, the artificial satellite 120 that is scheduled to de-orbit and fall.
The detected satellite 120 is a deorbiting satellite 120X.

For example, the de-orbit detection unit 211 detects the de-orbit satellite 120X as follows.
The second satellite constellation data 292 includes orbital data for each satellite 120 in the second satellite constellation 102. The orbital data for each satellite 120 includes a scheduled de-orbit date and time.
The orbit de-orbit detection unit 211 detects the artificial satellites 120 whose scheduled de-orbit time falls within a detection target time period. The detection target time period is a future time period that is a detection target.
The detected satellite 120 is a deorbiting satellite 120X.

In step S212, the avoidance action determination unit 212 determines an avoidance action for each artificial satellite 110 of the first satellite constellation 101 based on the first satellite constellation data 291 and the second satellite constellation data 292.
This avoidance action is an action for avoiding a collision with the deorbital satellite 120X. For example, the avoidance action is determined by the time period during which acceleration or deceleration is performed, the magnitude of the acceleration or deceleration, the direction of the acceleration or deceleration, and the like.

For example, the avoidance action determination unit 212 determines the avoidance action for each artificial satellite 110 as follows.
The first satellite constellation data 291 includes orbital data for each satellite 110 in the first satellite constellation 101 .
The avoidance action determination unit 212 receives as input the orbit data of the de-orbit satellite 120X during the de-orbit time period and the orbit data of each of the artificial satellites 110 during the de-orbit time period, and calculates an avoidance action determination algorithm, thereby determining an avoidance action.
The de-orbit window is the time period that includes the scheduled de-orbit date and time.
The avoidance action decision algorithm is an algorithm for deciding an avoidance action.

In step S213, the avoidance action instruction unit 213 generates a collision avoidance command for each artificial satellite 110. The collision avoidance command is a command for instructing an avoidance action.
The avoidance action instruction unit 213 then accesses the communication device 181 via the input/output interface 205 and transmits each collision avoidance command to each artificial satellite 110 using the communication device 181 .

Steps S221 and S222 are performed by each artificial satellite 110 in the first satellite constellation 101.

In step S221, the communication device 113 receives a collision avoidance command.

In step S222, the satellite controller 112 takes the avoidance action instructed by the collision avoidance command.
Specifically, the satellite controller 112 controls the thrusters 114 and the attitude controller 115 to take evasive action.

The operation of the second satellite constellation 102 will now be described.
There is a ground facility for controlling the second satellite constellation 102. This ground facility is referred to as the second ground facility.
The second ground facility includes a constellation control device and a communication device, similar to the ground facility 180 (see FIG. 1).
Even if the constellation control device of the second ground facility detects the deorbiting satellite 120X, it does not transmit a command to the deorbiting satellite 120X to instruct the satellite 110 to take action to avoid collision with each of the satellites 110.
Therefore, the deorbiting satellite 120X does not take any action to avoid a collision with each of the artificial satellites 110 of the first satellite constellation 101, and deorbits as scheduled.

***Description of the embodiment***
In the second embodiment, a common database of satellite constellations is provided among multiple megaconstellation operators.
The satellite constellation built at a low altitude will then carry out collision avoidance operations, while the satellite falling from a high altitude will not carry out automatic collision avoidance operations.

***Advantages of the Second Embodiment***
According to the second embodiment, it becomes possible to avoid collisions between the deorbiting satellite and each of the other satellites.

There is an altitude band near an orbital altitude of 340 km that is used only by certain mega-constellation operators. In this altitude band, a single operator can control all satellites and perform collision avoidance operations. On the other hand, when a mega-constellation operator using a high altitude performs active de-orbit operations, it is extremely difficult for the de-orbit satellite to pass through an orbital altitude where several thousand satellites are deployed comprehensively in the sky. In this case, it is rational for the low-orbit side to perform the avoidance operations.
Moreover, the second embodiment enables rational collision avoidance.

Embodiment 3.
Regarding the mode for avoiding collisions between the rocket and each artificial satellite, the following will describe mainly the points that differ from the first and second embodiments with reference to Figs. 8 to 13 .

***Configuration Description***
The configuration of the collision avoidance system 100C will be described with reference to FIG.
The collision avoidance system 100C includes a satellite constellation 103, a rocket 130, and a ground facility 190.

The satellite constellation 103 is a satellite constellation constructed in space. Specifically, the satellite constellation 103 is constructed at an orbital altitude where the rocket 130 passes.
The satellite constellation 103 is made up of a number of artificial satellites 110 .

The rocket 130 is launched into space and passes through the orbital altitude of the satellite constellation 103.

The ground facility 190 is a facility provided on the Earth 109 and controls the launch of the rocket 130 on the ground.
The ground facility 190 includes a launch control system 300 .

In the collision avoidance system 100C, a collision avoidance method is executed by the rocket 130 and the ground equipment 190.
This collision avoidance method avoids the rocket 130 colliding with each satellite 110 in the satellite constellation 103 .

The configuration of the rocket 130 will be described with reference to FIG.
The rocket 130 includes a rocket control device 131 , a communication device 132 , a propulsion device 133 , an attitude control device 134 , and a power supply device 135 .
The rocket control device 131 is a computer that controls the rocket 130. Specifically, the rocket control device 131 controls the propulsion device 133 and the attitude control device 134 in accordance with various commands transmitted from the ground facility 190. The rocket control device 131 also controls the propulsion device 133 and the attitude control device 134 in order to fly according to the launch schedule set by the ground facility 190.
The communication device 132 is a device that communicates with the ground facility 190. Specifically, the communication device 132 receives various commands and launch schedules from the ground facility 190.
The propulsion device 133 is a device that provides thrust to the rocket 130. Specifically, the propulsion device 133 is a solid fuel propulsion device and an electric propulsion device.
The attitude control device 134 is a device for controlling the attitude elements of the rocket 130. The attitude control device 134 changes each attitude element in a desired direction. Alternatively, the attitude control device 134 maintains each attitude element in a desired direction. The attitude control device 134 includes an attitude sensor, an actuator, and a controller.
The power supply unit 135 includes a solar cell, a battery, a power control device, etc., and supplies power to each device mounted on the rocket 130.

A supplementary explanation will be given regarding the rocket control device 131.
Rocket control device 131 includes processing circuitry.
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.
Dedicated hardware may be, for example, a single circuit, multiple circuits, a programmed processor, parallel programmed processors, an ASIC, an FPGA, or a combination of these.

The configuration of the launch control device 300 will be described with reference to FIG.
The launch control device 300 is a computer including hardware such as a processor 301, a memory 302, an auxiliary storage device 303, a communication device 304, and an input/output interface 305. These pieces of hardware are connected to each other via signal lines.

The processor 301 is an IC that performs arithmetic processing and controls other hardware. For example, the processor 301 is a CPU, a DSP, or a GPU.

Memory 302 is a volatile or non-volatile storage device. Memory 302 is also called a primary storage device or main memory. For example, memory 302 is a RAM. Data stored in memory 302 is saved in auxiliary storage device 303 as necessary.

The auxiliary storage device 303 is a non-volatile storage device. For example, the auxiliary storage device 303 is a ROM, a HDD, or a flash memory. Data stored in the auxiliary storage device 303 is loaded into the memory 302 as needed.

The communication device 304 is a receiver and a transmitter, for example, a communication chip or a NIC.
NIC is an abbreviation for Network Interface Card.

The input/output interface 305 is a port to which an input device and an output device are connected. For example, the input/output interface 305 is a USB terminal, the input devices are a keyboard and a mouse, and the output device is a display.

The launch control device 300 includes elements such as a schedule determination unit 311 and a schedule setting unit 312. These elements are realized by software.

The auxiliary storage device 303 stores a collision avoidance program for causing the computer to function as a schedule determination unit 311 and a schedule setting unit 312. The collision avoidance program is loaded into the memory 302 and executed by the processor 301.
The auxiliary storage device 303 further stores an OS. At least a part of the OS is loaded into the memory 302 and executed by the processor 301.
The processor 301 executes a collision avoidance program while executing the OS.

Input and output data for the collision avoidance program are stored in the memory unit 390 .
The memory 302 functions as the storage unit 390. However, a storage device such as the auxiliary storage device 303, a register in the processor 301, or a cache memory in the processor 301 may function as the storage unit 390 instead of the memory 302 or together with the memory 302.

The launch control device 300 may include multiple processors that replace the processor 301. The multiple processors share the functions of the processor 301.

The collision avoidance program can be recorded (stored) in a computer-readable manner on a non-volatile recording medium such as an optical disk or flash memory.

The configuration of the storage unit 390 will be described with reference to FIG.
The memory unit 390 stores target orbit data 391, satellite constellation data 392, and the like.
The target trajectory data 391 is data on the trajectory along which the rocket 130 is launched. The trajectory along which the rocket 130 is launched is referred to as the target trajectory.
The satellite constellation data 392 is orbital data of the satellite constellation 103 and includes orbital data of each artificial satellite 110 in the satellite constellation 103 .

*** Operation Description ***
The procedure of operation of the collision avoidance system 100C corresponds to a collision avoidance method.

The collision avoidance method will be described with reference to FIG.
Assume that a rocket 130 is scheduled to be launched into space.

Steps S311 and S312 are executed by the launch control device 300 of the ground facility 190.

In step S311, the schedule determination unit 311 determines the launch schedule of the rocket 130 based on the target orbit data 391 and the satellite constellation data 392.
This launch schedule is a schedule for avoiding collisions with each artificial satellite 110 of the satellite constellation 103. For example, the launch schedule is determined by the launch date and time, the acceleration at each time during flight, the attitude angle at each time during flight, etc.

For example, the schedule determination unit 311 determines the launch schedule of the rocket 130 as follows.
Satellite constellation data 392 includes orbital data for each satellite 110 in satellite constellation 103 .
The schedule determination unit 311 calculates a schedule determination algorithm using the target orbit data 391 of the rocket 130 and the orbit data of each artificial satellite 110 as input, thereby determining a launch schedule.

In step S312, the schedule setting unit 312 sets the launch schedule in the rocket control device 131 by communicating with the communication device 132 of the rocket 130.

Step S321 is executed by rocket 130.
In step S321, the rocket control device 131 flies the rocket 130 according to the launch schedule.
Specifically, the rocket control device 131 controls the propulsion device 133 and the attitude control device 134 to fly the rocket 130 according to the launch schedule.
This allows the rocket 130 to fly according to the launch schedule.

The operation of the satellite constellation 103 will now be described.
There is a ground facility for controlling the satellite constellation 103. This ground facility is referred to as the constellation ground facility.
The constellation ground facility includes a constellation control device and a communication device, similar to the ground facility 180 (see FIG. 1).
Even if the constellation control device detects the rocket 130 scheduled for launch, it does not transmit a command to each artificial satellite 110 of the satellite constellation 103 to instruct the satellites 110 to take action to avoid a collision with the rocket 130 .
Therefore, each artificial satellite 110 in the satellite constellation 103 will fly as planned without taking any action to avoid a collision with the rocket 130.

***Description of the embodiment***
In embodiment 3, a common database is provided between the rocket launch operator and the megaconstellation operator.
The launch vehicle operator then performs collision avoidance operations. On the other hand, low-orbit satellite constellations do not perform automatic collision avoidance operations.

Figure 13 shows an image of a satellite flight at an altitude of about 340 km. The curved lines represent the orbits. The stars represent the satellites. The circles represent the launch windows.
It is assumed that there are 40 orbital planes at an orbital altitude of approximately 340 kilometers, with 60 satellites per orbital plane, for a total constellation of 2,400 satellites.
The satellite speed is about 7.7 km/sec. The orbit is about 42,000 km, and there are 60 satellites per orbital plane, so the distance between satellites in the same orbital plane is about 700 km. Therefore, the waiting time from one satellite passing until the next satellite revisits is about 90 seconds. Also, each of the 40 orbital planes revisits twice in 24 hours, so the time between adjacent orbital planes is about 18 minutes.

Assume that a satellite constellation consisting of three groups of artificial satellites at different orbital altitudes is constructed around an altitude of 340 km. Each group of artificial satellites consists of about 2,500 artificial satellites. In other words, this satellite constellation has a total of about 7,500 satellites. In this case, the three orbital planes basically rotate asynchronously.
Furthermore, assume that a rocket is launched from Guiana near the equator to an altitude of more than 340 km. In this case, the launch window during which the rocket can be launched without colliding with the satellite constellation is limited to only the gap of several minutes between the passing of one orbital plane and the crossing of the next. If the launch orbit of the rocket overlaps with the orbital plane, the risk of collision is high because the interval between satellites is only about 90 seconds. Note that the rotation speed of the orbital planes differs for each orbital altitude, so the interval between the passing of one orbital plane and the crossing of the next orbital plane varies randomly.

Let's assume that a rocket is launched from Tanegashima, which is located at approximately 30 degrees north latitude. In this case, the launch window will be narrow depending on the orbital inclination of the satellite constellation. If there is a satellite constellation with an orbital inclination of approximately 30 degrees, it will be difficult to avoid collisions in reality.

To avoid collisions during such a limited launch window, the megaconstellation operator needs to share the satellite orbital information held by the megaconstellation operator and the rocket launch plan information held by the rocket launch operator, and one of them needs to carry out avoidance operations.

When a rocket is launched from a ground base, the launch site's location coordinates are fixed in Earth-fixed coordinates. However, the orbital plane and satellite position in Earth-fixed coordinates change from moment to moment. Therefore, the information shared is a function of time and location coordinates.
When a rocket is launched from a moving body (such as a sea launch), the position coordinates of the launch site are also managed as time-varying parameters.

If both the satellite constellation operator and the rocket launch operator were to be equipped with autonomous collision avoidance capabilities and to independently carry out autonomous collision avoidance operations, a new risk of collision would arise.
Therefore, in the third embodiment, information on time and position coordinates is shared. Then, only one operator (the rocket launch operator) exercises collision avoidance measures. The other operator (the satellite constellation operator) operates as planned. This ensures collision avoidance.

***Advantages of Third Embodiment***
According to the third embodiment, it becomes possible to avoid collisions between the rocket and each artificial satellite.

If a mega-constellation of thousands of satellites were constructed at an orbital altitude of around 340 kilometers, there would be a risk of a collision between the rockets launched.
In this orbital altitude band, it is assumed that a single operator will operate several thousand satellites in synchronous operation, allowing rockets to navigate between the gaps between satellites in the same orbital plane and between adjacent orbits to avoid collisions.
Therefore, according to the third embodiment, it is possible to avoid collisions between the rocket and each artificial satellite.

Embodiment 4.
Regarding the mode for avoiding collisions between the rocket and each artificial satellite, the following will explain mainly the points that differ from the first to third embodiments with reference to Figs. 14 to 17.

***Configuration Description***
The configuration of the collision avoidance system 100D will be described with reference to FIG.
The collision avoidance system 100D includes a satellite constellation 103, a rocket 130, and a ground facility 180.

Ground equipment 180 is equipment installed on Earth 109 that controls satellite constellation 103 on the ground.

In the collision avoidance system 100D, a collision avoidance method is implemented by the satellite constellation 103 and the ground facility 180.
This collision avoidance method avoids rocket 130 colliding with each satellite 110 in satellite constellation 103 .

The configuration of the artificial satellite 110 is the same as that in embodiment 1 (see Figure 2).

The configuration of the constellation control device 200 will be described with reference to FIG.
The constellation control device 200 includes elements such as an avoidance action determination unit 212 and an avoidance action instruction unit 213. These elements are realized by software.
The collision avoidance program causes the computer to function as an avoidance action determination unit 212 and an avoidance action instruction unit 213 .

The configuration of the storage unit 290 will be described with reference to FIG.
The memory unit 290 stores satellite constellation data 293, a launch schedule 294, and the like.
The satellite constellation data 293 is orbital data of the first satellite constellation 101 and includes orbital data of each artificial satellite 110 in the first satellite constellation 101 .
The launch schedule 294 is a launch schedule for the rocket 130. For example, the launch schedule is determined by the launch date and time, the acceleration at each time during flight, the attitude angle at each time during flight, and the like.

*** Operation Description ***
The procedure of operation of the collision avoidance system 100D corresponds to a collision avoidance method.

A collision avoidance method will be described with reference to FIG.
Assume that a rocket 130 is scheduled to be launched into space.

Steps S411 and S412 are executed by the constellation control device 200 of the ground equipment 180.

In step S411, the avoidance action determination unit 212 determines an avoidance action for each artificial satellite 110 of the satellite constellation 103 based on the satellite constellation data 293 and the launch schedule 294.
This evasive action is an action for avoiding a collision with the rocket 130. For example, the evasive action is determined by the time period during which acceleration or deceleration is performed, the magnitude of the acceleration or deceleration, the direction of the acceleration or deceleration, and the like.

For example, the avoidance action determination unit 212 determines the avoidance action for each artificial satellite 110 as follows.
Satellite constellation data 293 includes orbital data for each satellite 110 in satellite constellation 103 .
The avoidance action determination unit 212 receives as input the launch schedule 294 of the rocket 130 and the orbital data of each artificial satellite 110 during the rocket's passing time period, and calculates an avoidance action decision algorithm, thereby determining an avoidance action.
The rocket pass time period is the time period during which the rocket 130 passes the orbital altitude of the satellite constellation 103. The rocket pass time period is calculated using the launch schedule 294.
The avoidance action decision algorithm is an algorithm for deciding an avoidance action.

In step S412, the avoidance action instruction unit 213 generates a collision avoidance command for each artificial satellite 110. The collision avoidance command is a command for instructing an avoidance action.
The avoidance action instruction unit 213 then accesses the communication device 181 via the input/output interface 205 and transmits each collision avoidance command to each artificial satellite 110 using the communication device 181 .

Steps S421 and S422 are performed by each satellite 110 in the satellite constellation 103.

In step S421, the communication device 113 receives a collision avoidance command.

In step S422, the satellite controller 112 takes evasive action as instructed by the collision avoidance command.
Specifically, the satellite controller 112 controls the thrusters 114 and the attitude controller 115 to take evasive action.

The operation of the rocket 130 will now be described.
There is a ground facility for controlling the launch of the rocket 130. This ground facility is called the launch ground facility.
The launch ground facility includes a launch control device similar to ground facility 190 (see FIG. 8).
The launch controller does not alter the launch schedule 294 of the rocket 130 even if the satellite constellation 103 is present.
Therefore, the rocket 130 flies according to the launch schedule 294 without taking any action to avoid collision with each of the artificial satellites 110 in the satellite constellation 103.

***Description of the embodiment***
In embodiment 4, a common database is provided between the rocket launch operator and the megaconstellation operator.
The satellite constellation constructed at a low altitude will then carry out collision avoidance operations, while the rocket launch company will carry out the launch at the scheduled time announced in advance.

***Advantages of the Fourth Embodiment***
According to the fourth embodiment, it becomes possible to avoid collisions between the rocket and each artificial satellite.

A satellite that rendezvous with a specific planet is called a planetary exploration satellite. There are strict constraints on the timing of launching a planetary exploration satellite. Furthermore, if the orbital plane of a low-orbit mega-constellation is in the planned launch orbit, there is a risk of collision.
If the megaconstellation can grasp this situation in advance and change the altitudes of all satellites simultaneously, the relative rotation rate between the Earth's rotation and the orbital plane will change, making it possible to launch at the desired timing while avoiding collisions.
Therefore, according to the fourth embodiment, it is possible to avoid collisions between the rocket and each artificial satellite.

Embodiment 5.
Regarding a mode for avoiding collisions between a geostationary satellite and each artificial satellite in a geostationary transfer orbit, the following will explain mainly the points that differ from the first to fourth embodiments with reference to Figs. 18 to 22.

***Configuration Description***
The configuration of the collision avoidance system 100E will be described with reference to FIG.
The collision avoidance system 100E includes a satellite constellation 103, a rocket 130, and a ground facility 180.

Ground equipment 180 is equipment installed on Earth 109 that controls satellite constellation 103 on the ground.

The rocket 130 is a rocket for launching the geostationary satellite 140 into the geostationary transfer orbit 104.

The perigee altitude of geostationary transfer orbit 104 is higher than the orbital altitude at which satellite constellation 103 is constructed.

In the collision avoidance system 100E, a collision avoidance method is implemented by the satellite constellation 103 and the ground facility 180.
This collision avoidance method avoids collisions of geostationary satellite 140 with each artificial satellite 110 in satellite constellation 103 .

The configuration of the artificial satellite 110 is the same as that in embodiment 1 (see Figure 2).

The configuration of the constellation control device 200 is the same as that in embodiment 4 (see FIG. 15).

The configuration of the storage unit 290 will be described with reference to FIG.
The storage unit 290 stores satellite constellation data 293, a stationary transition scheduler 295, and the like.
The geostationary transfer scheduler 295 is a schedule until the geostationary satellite 140 is injected into the geostationary orbit, and indicates a schedule for the geostationary satellite 140 to fly in the geostationary transfer orbit 104 .

*** Operation Description ***
The procedure of operation of the collision avoidance system 100E corresponds to a collision avoidance method.

The collision avoidance method will be described with reference to FIG.
Assume that a rocket 130 is scheduled to be launched into space.

Steps S511 and S512 are executed by the constellation control device 200 of the ground equipment 180.

In step S511, the avoidance action determination unit 212 determines an avoidance action for each artificial satellite 110 of the satellite constellation 103 based on the satellite constellation data 293 and the geostationary transition scheduler 295.
This avoidance action is an action to avoid a collision with the geostationary satellite 140 in the geostationary transfer orbit 104. For example, the avoidance action is determined by the time period during which acceleration or deceleration is performed, the magnitude of the acceleration or deceleration, the direction of the acceleration or deceleration, etc.

For example, the avoidance action determination unit 212 determines the avoidance action for each artificial satellite 110 as follows.
Satellite constellation data 293 includes orbital data for each satellite 110 in satellite constellation 103 .
The avoidance action determination unit 212 receives as input the geostationary transfer scheduler 295 of the geostationary satellite 140 and the orbit data of each artificial satellite 110 during the satellite passing time period, and calculates an avoidance action determination algorithm, thereby determining the avoidance action.
The satellite passing time period is the time period during which the geostationary satellite 140 passes through the orbital altitude of the satellite constellation 103. The satellite passing time period is calculated using the geostationary transfer scheduler 295.
The avoidance action decision algorithm is an algorithm for deciding an avoidance action.

In step S512, the avoidance action instruction unit 213 generates a collision avoidance command for each artificial satellite 110. The collision avoidance command is a command for instructing an avoidance action.
The avoidance action instruction unit 213 then accesses the communication device 181 via the input/output interface 205 and transmits each collision avoidance command to each artificial satellite 110 using the communication device 181 .

Steps S521 and S522 are performed by each satellite 110 in the satellite constellation 103.

In step S521, the communication device 113 receives a collision avoidance command.

In step S522, the satellite controller 112 takes evasive action as instructed by the collision avoidance command.
Specifically, the satellite controller 112 controls the thrusters 114 and the attitude controller 115 to take evasive action.

The operation of the geostationary satellite 140 will now be described.
There is a ground facility for controlling the launch of the rocket 130. This ground facility is called the launch ground facility.
The launch ground facility includes a launch control device similar to ground facility 190 (see FIG. 8).
The launch controller does not change the geostationary transfer scheduler 295 of the geostationary satellite 140 even if the satellite constellation 103 is present.
Therefore, the geostationary satellite 140 flies in the geostationary transfer orbit 104 according to the geostationary transfer scheduler 295 without taking any action to avoid collision with each artificial satellite 110 of the satellite constellation 103 .

***Description of the embodiment***
In embodiment 5, a common database is provided between the geostationary orbit launch operator and the megaconstellation operator.
The satellite constellation constructed at a low altitude will then carry out collision avoidance operations, while the geostationary orbit launch operator will carry out the launch at the scheduled time announced in advance.

***Advantages of Fifth Embodiment***
According to the fifth embodiment, it becomes possible to avoid collisions between a geostationary satellite and each artificial satellite in a geostationary transfer orbit.

FIG. 21 shows an example of a geostationary transfer orbit (GTO). The solid ellipse represents a geostationary transfer orbit. The solid circle represents a geostationary orbit. The dashed circle represents the orbit of a satellite constellation. The star represents a point where there is a risk of collision. The black circle represents the apogee or perigee of the geostationary transfer orbit. FIG. 22 shows an example of a geostationary transfer orbit. The mesh-like curve covering the Earth 109 represents the orbit of a satellite constellation. The circle going around the Earth 109 represents a geostationary orbit. The circular arc from the Earth 109 to the geostationary orbit represents a geostationary transfer orbit. The star represents the apogee of the geostationary transfer orbit.
Generally, a geostationary orbit satellite is equipped with a propulsion device called an apogee kick motor. The geostationary orbit satellite is then launched into a geostationary transfer orbit by a rocket. Thereafter, the geostationary orbit satellite raises the orbital altitude of the perigee by operating the apogee kick motor at the apogee. As a result, the geostationary orbit satellite reaches the geostationary orbit. In this case, an orbital transfer (orbit raising) that exceeds an altitude of 340 km above the equator is performed on the satellite side.
The timing of operating the apogee kick motor in a geostationary transfer orbit cannot necessarily be freely selected because of constraints such as the target geostationary position.
Therefore, a common database will be prepared between the geostationary orbit launch operator and the mega-constellation operator. The satellite constellation operator will then be able to determine whether or not a collision will occur by implementing collision avoidance operations.
Therefore, according to the fifth embodiment, it is possible to avoid collisions between a geostationary satellite and each artificial satellite in a geostationary transfer orbit.

Embodiment 6.
Regarding a mode for avoiding collisions between a geostationary satellite and each artificial satellite in a geostationary transfer orbit, the following will explain mainly the points that differ from the first to fifth embodiments with reference to Figs. 23 to 27.

***Configuration Description***
The configuration of the collision avoidance system 100F will be described with reference to FIG.
The collision avoidance system 100F includes a satellite constellation 103, a rocket 130, and a ground facility 190.

The ground facility 190 is a facility installed on the Earth 109, and controls the launch of the rocket 130 on the ground.

The rocket 130 is a rocket for launching the geostationary satellite 140 into the geostationary transfer orbit 104.

In the collision avoidance system 100F, a collision avoidance method is executed by the rocket 130 and the ground equipment 190.
This collision avoidance method avoids collisions of geostationary satellite 140 with each artificial satellite 110 in satellite constellation 103 .

The configuration of the rocket 130 will be described with reference to FIG.
The rocket 130 is
The rocket 130 is configured to include a satellite launch device 139 in addition to the elements explained in the third embodiment (see FIG. 9).
The rocket control device 131 further controls the satellite launch device 139 .
The satellite injection device 139 is a device for injecting the geostationary satellite 140 mounted on the rocket 130 into the geostationary transfer orbit 104. Specifically, the satellite injection device 139 holds the geostationary satellite 140 until the injection point and separates the geostationary satellite 140 at the injection point.

The configuration of the launch control device 300 will be described with reference to FIG.
The launch control device 300 includes components such as a geostationary transfer orbit determination unit 321 and an orbit parameter setting unit 322. These components are realized by software.
The collision avoidance program causes the computer to function as a geostationary transfer orbit determination unit 321 and an orbit parameter setting unit 322 .

The configuration of the storage unit 390 will be described with reference to FIG.
The storage unit 390 stores geostationary orbit data 393, satellite constellation data 392, and the like.
The geostationary orbit data 393 indicates the geostationary orbit around which the geostationary satellite 140 is scheduled to revolve.

*** Operation Description ***
The procedure of operation of the collision avoidance system 100F corresponds to a collision avoidance method.

A collision avoidance method will be described with reference to FIG.
Assume that a rocket 130 is scheduled to be launched into space.

Steps S611 and S612 are executed by the launch control device 300 of the ground facility 190.

In step S611, the geostationary transfer orbit determination unit 321 determines the geostationary transfer orbit 104 based on the geostationary orbit data 393 and the satellite constellation data 392.

For example, the geostationary transfer orbit determination unit 321 determines the geostationary transfer orbit 104 as follows.
Satellite constellation data 392 indicates the orbital altitude at which satellite constellation 103 is constructed.
The geostationary transfer orbit determination unit 321 receives the geostationary orbit data 393 and the satellite constellation data 392 and calculates a geostationary transfer orbit determination algorithm, thereby determining the geostationary transfer orbit 104.
The perigee altitude of the geostationary transfer orbit 104 is higher than the orbital altitude at which the satellite constellation 103 is constructed.

In step S612, the trajectory parameter setting unit 322 sets the trajectory parameters in the rocket control device 131 by communicating with the communication device 132 of the rocket 130.
The orbit parameters are parameters for specifying the geostationary transfer orbit 104 .

Step S621 is executed by rocket 130.
In step S621, the rocket control device 131 injects the geostationary satellite 140 into the geostationary transfer orbit 104 specified by the orbit parameters.
Specifically, the rocket control device 131 controls the propulsion device 133 and the attitude control device 134 to fly the rocket 130 to the launch point of the geostationary satellite 140. Then, the rocket control device 131 controls the satellite launch device 139 to separate the geostationary satellite 140 at the launch point.
As a result, the geostationary satellite 140 is injected into the geostationary transfer orbit 104. Thereafter, the geostationary satellite 140 transfers from the geostationary transfer orbit 104 to a geostationary orbit.

The operation of the satellite constellation 103 will now be described.
There is a ground facility for controlling the satellite constellation 103. This ground facility is referred to as the constellation ground facility.
The constellation ground facility includes a constellation control device and a communication device, similar to the ground facility 180 (see FIG. 1).
Even if the constellation control device detects the rocket 130 scheduled for launch, it does not transmit a command to each artificial satellite 110 of the satellite constellation 103 to instruct the satellite to take action to avoid a collision with the geostationary satellite 140 .
Therefore, each artificial satellite 110 in the satellite constellation 103 flies as scheduled without taking any action to avoid collision with the geostationary satellite 140.

***Description of the embodiment***
In the sixth embodiment, the altitude of the perigee of the geostationary transfer orbit into which the geostationary satellite is launched by the rocket is set to be higher than the orbital altitude at which the mega-constellation is constructed. In other words, the rocket side performs collision avoidance.

***Advantages of Sixth Embodiment***
According to the sixth embodiment, it becomes possible to avoid collisions between a geostationary satellite and each artificial satellite in a geostationary transfer orbit.

The perigee altitude of a conventional geostationary transfer orbit is lower than the orbital altitude of a mega-constellation, and because a geostationary satellite passes obliquely through the orbital plane of a mega-constellation above the equator, there is a high risk of collision.
Therefore, in the sixth embodiment, the geostationary satellite is launched to a higher altitude by a rocket. Therefore, the slope when the geostationary satellite passes through the danger altitude is small. And, the geostationary satellite passes through the danger altitude in a short time.
Therefore, according to the sixth embodiment, it is possible to avoid collisions between a geostationary satellite and each artificial satellite in a geostationary transfer orbit.

Embodiment 7.
Regarding the mode for avoiding collisions between the rocket and each artificial satellite, the following will explain mainly the points that differ from the first to sixth embodiments with reference to Figs. 28 and 29.

***Configuration Description***
The configuration of the collision avoidance system 100G will be described with reference to FIG.
The collision avoidance system 100G includes a satellite constellation 103, a rocket 130, and a ground facility 180.

Ground equipment 180 is equipment installed on Earth 109 that controls satellite constellation 103 on the ground.

In the collision avoidance system 100G, a collision avoidance method is implemented by the satellite constellation 103 and the ground facility 180.
This collision method avoids the rocket 130 colliding with each satellite 110 in the satellite constellation 103 .

The configuration of the artificial satellite 110 is the same as that in embodiment 1 (see Figure 2).

The configuration of the constellation control device 200 is the same as that in embodiment 4 (see Figures 15 and 16).

*** Operation Description ***
The procedure of operation of the collision avoidance system 100G corresponds to a collision avoidance method.

The collision avoidance method is the same as the procedure in the fourth embodiment (see FIG. 17).
However, the avoidance behavior of each artificial satellite 110 has the following characteristics.

The first feature is that all satellites 110 in the satellite constellation 103 change velocity at the same time.
The second feature is that it changes speed twice.
The first velocity change causes all of the satellites 110 in the satellite constellation 103 to change their orbital altitudes simultaneously.
The second velocity change causes all of the satellites 110 in the satellite constellation 103 to return to their orbital altitudes simultaneously.

The relationship between the velocity of the artificial satellite 110 and the orbital altitude of the artificial satellite 110 will be described with reference to FIG.
When the flight speed of the artificial satellite 110 increases, the altitude of the artificial satellite 110 increases. When the altitude of the artificial satellite 110 increases, the speed of the artificial satellite 110 relative to the ground decreases.
When the flight speed of the artificial satellite 110 decreases, the altitude of the artificial satellite 110 decreases. When the altitude of the artificial satellite 110 decreases, the ground speed of the artificial satellite 110 increases.

***Description of the embodiment***
In the seventh embodiment, a mega-constellation operator operates a large number of satellites in close orbit at a coordinated orbital altitude. All the satellites are equipped with propulsion devices, and the propulsion devices are used to simultaneously increase or decrease their speed.

***Effects of the Seventh Embodiment***
According to the seventh embodiment, it becomes possible to avoid collisions between the rocket and each artificial satellite.

A satellite that is intended to rendezvous with a specific asteroid is called a planetary exploration satellite. If the launch window is constrained severely and the orbital plane of a mega-constellation is on the planned launch orbit of a planetary exploration satellite, there is a risk of collision. If the mega-constellation operator is aware of this situation in advance, the following operation is possible. If all the satellites being operated are accelerated simultaneously by the thrusters, the orbital altitude of all the satellites will rise and the ground speed of all the satellites will decrease. As a result, the relative rotation speed between the orbital plane and the Earth's rotation will change. This makes it possible to delay the timing when the orbital plane of the mega-constellation revisits the planned launch orbit. As a result, a safe launch that complies with the constraints of the launch window is possible. After the launch is completed, all the satellites will decelerate and the orbital altitude of all the satellites will return to the specified altitude.

Mega-constellation operators may provide services by linking satellites in the same orbital plane, or satellites in adjacent orbital planes, through communication. In this case, if only some of the satellites perform collision avoidance operations, it will cause problems in the linked services.
According to the seventh embodiment, the orbital altitudes of all satellites are changed synchronously while the relative relationships between all satellites are maintained, so that collision avoidance can be achieved without interfering with coordinated services.

Embodiment 8.
Regarding the mode for avoiding collision between space debris and each artificial satellite, the following will explain mainly the points that differ from the first to seventh embodiments with reference to Figs. 30 to 33.

***Configuration Description***
The configuration of the collision avoidance system 100H will be described with reference to FIG.
The collision avoidance system 100H includes a satellite constellation 103 and a ground facility 180.

Ground equipment 180 is equipment installed on Earth 109 that controls satellite constellation 103 on the ground.

In the collision avoidance system 100H, a collision avoidance method is implemented by the satellite constellation 103 and the ground facility 180.
This collision avoidance method prevents debris 105 from colliding with each satellite 110 in satellite constellation 103 .

The configuration of the artificial satellite 110 is the same as that in embodiment 1 (see Figure 2).

The configuration of the constellation control device 200 will be described with reference to FIG.
The constellation control device 200 includes elements such as a collision warning reception unit 221, a target satellite group detection unit 222, an avoidance action decision unit 223, and an avoidance action instruction unit 224. These elements are realized by software.
The collision avoidance program causes the computer to function as a collision warning receiving unit 221 , a target satellite group detection unit 222 , an avoidance action decision unit 223 , and an avoidance action instruction unit 224 .

The configuration of the storage unit 290 will be described with reference to FIG.
The memory unit 290 stores satellite constellation data 293, collision warning data 296, and the like.
The collision warning data 296 indicates the content of the collision warning issued by the collision warning system. Specifically, the collision warning data 296 indicates a predicted collision time zone, a predicted collision area, and the like.
The predicted collision time period is a time period during which the debris 105 is predicted to collide with the artificial satellite 110 .
The predicted collision area is an area in which the debris 105 is predicted to collide with the artificial satellite 110 .

*** Operation Description ***
A collision avoidance method will be described with reference to FIG.
Assume that a collision warning has been issued.

Steps S811 to S814 are executed by the constellation control device 200 of the ground equipment 180.

In step S811, the collision warning receiving unit 221 receives the collision warning data 296.
Then, the collision warning receiving unit 221 stores the collision warning data 296 in the memory unit 290 .

In step S 812 , the target satellite group detection unit 222 detects the target satellite group based on the satellite constellation data 293 and the collision warning data 296 .
A constellation of interest is one or more satellites of interest.
The target satellite is an artificial satellite 110 that may collide with the debris 105. Specifically, the target satellite is an artificial satellite 110 that passes through a collision prediction region during a collision prediction time period.

For example, the target satellite group detection unit 222 detects the target satellite group as follows.
The satellite constellation data 293 includes orbital data for each satellite 110 in the satellite constellation 103. The orbital data for each satellite 110 indicates the points through which each satellite 110 passes at each time.
The target satellite group detection unit 222 receives the satellite constellation data 293 and the collision warning data 296 and calculates a target satellite group detection algorithm, thereby detecting the target satellite group.
The target satellite group detection algorithm is an algorithm for detecting a target satellite group.

In step S813, the avoidance action determination unit 223 determines an avoidance action for each target satellite based on the orbit data and the collision warning data 296 of each target satellite.
This avoidance action is an action for avoiding a collision with the debris 105. For example, the avoidance action is determined by the time period during which acceleration or deceleration is performed, the magnitude of the acceleration or deceleration, the direction of the acceleration or deceleration, and the like.

The avoidance actions of each target satellite have the following characteristics:
The first feature is that all of the target satellites change velocity at the same time.
The second feature is that it changes speed twice.
The first speed change causes all target satellites to change their orbital altitudes simultaneously.
The second speed change causes all target satellites to return to their orbital altitudes simultaneously.

For example, the avoidance action determination unit 223 determines the avoidance action for each target satellite as follows.
The avoidance action determination unit 223 receives the orbit data of each target satellite and the collision warning data 296, and calculates an avoidance action determination algorithm, thereby determining an avoidance action.
The avoidance action decision algorithm is an algorithm for deciding an avoidance action.

In step S814, the avoidance action instruction unit 224 generates a collision avoidance command for each target satellite. The collision avoidance command is a command for instructing an avoidance action.
The avoidance action instruction unit 224 then accesses the communication device 181 via the input/output interface 205 and uses the communication device 181 to transmit each collision avoidance command to each target satellite.

Steps S821 and S822 are performed by each target satellite in the satellite constellation 103.

In step S821, the communication device 113 receives a collision avoidance command.

In step S822, the satellite controller 112 takes evasive action as instructed by the collision avoidance command.
Specifically, the satellite controller 112 controls the thrusters 114 and the attitude controller 115 to take evasive action.

***Description of the embodiment***
In the eighth embodiment, when there are many satellites passing through a danger zone for which a collision warning has been issued during a collision predicted time period, the group of satellites near the danger zone are simultaneously accelerated or decelerated by the propulsion devices.

***Effects of the Eighth Embodiment***
According to the eighth embodiment, it becomes possible to avoid collisions between space debris and each artificial satellite.

In a low-orbit satellite constellation, when multiple satellites fly closely together in phase and only one of them independently performs collision avoidance operations, there is a risk that the satellite will collide with another satellite flying nearby.
If multiple satellites were to perform collision avoidance operations independently and in an uncoordinated manner, there would be a risk that the satellites taking evasive action would collide with each other.
On the other hand, if all satellites operating in the same orbital plane accelerate simultaneously, all satellites in that orbital plane can change their orbital altitudes without colliding.

By simultaneously increasing the speed of multiple satellites on the same orbital plane that are at risk of collision, avoidance maneuvers can be achieved. In addition, the new collision risk associated with avoidance maneuvers is no longer limited to consideration of collisions with satellites in front and behind.
After a collision is successfully avoided during the period when the collision warning was issued, multiple aircraft can simultaneously slow down and return to their original operating state.
In this way, embodiment 8 makes it possible to avoid collisions between space debris and each artificial satellite.

***Additional Information on the Implementation ***
Each embodiment is an example of a preferred embodiment, and is not intended to limit the technical scope of the present disclosure. Each embodiment may be implemented in part or in combination with other embodiments. The procedures described using flow charts, etc. may be modified as appropriate.
The "part" that is an element of the constellation control device 200 or the launch control device 300 may be read as a "process" or a "step."

100A to 100F collision avoidance system, 101 first satellite constellation, 102 second satellite constellation, 103 satellite constellation, 104 geostationary transfer orbit, 105 debris, 109 earth, 110 artificial satellite, 110X deorbiting satellite, 111 monitoring device, 112 satellite control device, 113 communication device, 114 propulsion device, 115 attitude control device, 116 power supply device, 120 artificial satellite, 120X deorbiting satellite, 130 rocket, 131 rocket control device, 132 communication device, 133 propulsion device, 134 attitude control device, 135 power supply device, 139 satellite launch device, 140 geostationary satellite, 180 ground equipment, 181 communication device, 190 ground equipment, 200 constellation control device, 201 processor, 202 memory, 203 auxiliary storage device, 204 Communication interface, 205 Input/output interface, 211 Orbit departure detection unit, 212 Avoidance action determination unit, 213 Avoidance action instruction unit, 221 Collision warning reception unit, 222 Target satellite group detection unit, 223 Avoidance action determination unit, 224 Avoidance action instruction unit, 290 Storage unit, 291 First satellite constellation data, 292 Second satellite constellation data, 293 Satellite constellation data, 294 Launch schedule, 295 Geostationary transfer scheduler, 296 Collision warning data, 300 Launch control device, 301 Processor, 302 Memory, 303 Auxiliary storage device, 304 Communication device, 305 Input/output interface, 311 Schedule determination unit, 312 Schedule setting unit, 321 Geostationary transfer orbit determination unit, 322 Orbit parameter setting unit, 390 Storage unit, 391 Target orbit data, 392 Satellite constellation data, 393 Geostationary orbit data.

Claims (6)

1. A collision avoidance method implemented by a satellite constellation and a ground facility controlling said satellite constellation on the ground, comprising:
When a rocket is launched that is scheduled to pass through the orbital altitude of the satellite constellation, the ground facility transmits a collision avoidance command to each satellite of the satellite constellation to cause all satellites of the satellite constellation to simultaneously change their speed;
A collision avoidance method in which each satellite of the satellite constellation receives a collision avoidance command transmitted by the ground equipment and changes its velocity simultaneously with other satellites of the satellite constellation in accordance with the received collision avoidance command. the collision avoidance command is a command for changing speed twice,
2. The collision avoidance method of claim 1 , wherein each satellite of the satellite constellation changes its orbital altitude by a first velocity change and then returns its orbital altitude by a second velocity change. 1. A ground facility for controlling a satellite constellation, comprising:
A ground facility including a constellation control device that transmits collision avoidance commands to each satellite in the satellite constellation to cause all satellites in the satellite constellation to simultaneously change their speed when a rocket scheduled to pass through the orbital altitude of the satellite constellation is launched. 1. A collision avoidance method implemented by a satellite constellation and a ground facility controlling said satellite constellation on the ground, comprising:
When a collision warning is issued, the ground equipment transmits a collision avoidance command to each target satellite in the satellite constellation that is an artificial satellite passing through a collision prediction area during a collision prediction time period, for causing all target satellites to simultaneously change their speeds;
A collision avoidance method in which each target satellite receives a collision avoidance command transmitted by the ground facility, and changes its speed simultaneously with the other target satellites in accordance with the received collision avoidance command. the collision avoidance command is a command for changing speed twice,
5. The collision avoidance method according to claim 4 , wherein each target satellite changes its orbital altitude by a first velocity change and then returns its orbital altitude by a second velocity change. 1. A ground facility for controlling a satellite constellation, comprising:
A ground facility equipped with a constellation control device that, when a collision warning is issued, transmits a collision avoidance command to all target satellites in the satellite constellation, which are artificial satellites that pass through a collision prediction area during a collision prediction time period, to simultaneously change their speed.

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