JP2008126876A - Observation satellite group control system, observation satellite, ground station, and observation satellite group control method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an observation satellite group control system capable of observing a target observation area in a short time after establishing an observation plan by using a plurality of observation satellite groups orbiting the earth. <P>SOLUTION: A satellite information control unit is provided, which selects at least one observation satellite among a plurality of observation satellites orbiting around the earth, sends information on the target observation point corresponding to the selected observation satellite, and sends an orbit changing command for descending the orbit altitude of the selected observation satellite. When the observation satellite receives the information on the target observation point and the orbit changing command to be sent from the satellite information control unit, it descends its orbit altitude, and observes the target observation point after descending the orbit altitude. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an observation satellite group control system that observes an observation target point using a plurality of observation satellite groups, and a control method for operating the observation satellites, ground stations, and observation satellite groups.

  2. Description of the Related Art Conventionally, a system is known that uses a plurality of satellites to fly in orbit around the earth and observes the earth by remote sensing technology (see, for example, Patent Document 1).

JP 2006-168461 A

  As an observation system that detects a disaster occurrence early and reliably, a network is connected to a distribution center of satellite images, and an area image of a predetermined area is displayed from the distribution center. This observation system is intended to be useful for confirming the occurrence of a disaster by imaging a specific area with an image pickup device mounted on a geostationary satellite and highlighting the obtained differential image within the specific area (for example, Patent Document 2).

JP-A-2005-78566

  Since the conventional observation system disclosed in Patent Document 2 uses a geostationary satellite, there is a problem in that when observing a disaster area in an emergency, the resolution of the observation image is poor and the disaster situation cannot be confirmed in detail. It was.

  On the other hand, the resolution of a captured image can be improved by observing a predetermined area on the ground using an orbiting satellite orbiting a low orbit over the earth.

  However, when an orbiting satellite is used alone, it usually takes a long time from the time when the observation command is sent to the satellite until the satellite passes through the damaged ground, and the time interval from the observation command transmission to the observation is long. become longer. For this reason, unless the timing of the satellite orbit position coincides with the observation target point, the time loss between the planning of the observation plan and the execution of the observation is large, and the observation target point can be quickly determined even in an emergency. There was a problem that it could not be observed.

  In addition, it is conceivable to shorten the observation time interval by arranging a plurality of observation satellites in the orbit, but in this case, the cost of manufacturing the satellite and launching the satellite is increased depending on the number of satellites, and the entire system is expensive. There was a problem that it could not be put into practical use as it was.

  Patent Document 2 describes an observation system that performs formation flight using a plurality of satellites. However, the arrangement interval between the satellites is short, and the time loss until the observation execution is performed as in the case of using a single orbiting satellite. There is a problem that is large. From such a point of view, an observation system that can observe a target point in a short time after making an observation plan using a plurality of satellites is desired.

  The present invention has been made in order to solve the above-described problem, and an observation satellite capable of observing an observation target area in a short time after making an observation plan using a plurality of observation satellites orbiting the earth The purpose is to provide a group control system.

  An observation satellite group control system according to the present invention selects a plurality of observation satellites flying in mutually different earth orbits and at least one observation satellite from among the plurality of observation satellites, and an observation target point corresponding to the selected observation satellite A satellite information management unit that transmits an orbital change command for lowering the orbital height of the selected observation satellite, and the observation satellite is the observation target point transmitted from the satellite information management unit When the information and the orbit change command are received, the orbital altitude is lowered, and the observation target point is observed after the orbital altitude is lowered.

  The observation satellite may be discarded in orbit after transmitting the observation data of the observation target point.

  In addition, the observation satellite according to the present invention flies in a different orbit around the earth than the other observation satellites, and when receiving the information of the observation target point from the satellite information management unit, the orbital altitude is lowered. The observation target point is observed after the descent and the observation data of the observation target point is transmitted. After the observation data is transmitted, the observation target point is discarded.

  In addition, the ground station according to the present invention selects at least one observation satellite from a plurality of observation satellites flying in different orbits around the earth, and sends information on an observation target point corresponding to the selected observation satellite. The satellite information management unit that sends out the orbital change command to lower the orbital altitude of the selected observation satellite, and the observation target point information and the orbital change command sent from the satellite information management unit, either directly or as a data relay satellite or flying vehicle A communication antenna for transmitting to the selected observation satellite via the communication antenna, the communication antenna directly or via a data relay satellite or flying object, after the orbital altitude of the observation satellite is lowered, The observation information of the observation target point is received from.

  The observation satellite group control method according to the present invention includes a step of selecting at least one observation satellite from a plurality of observation satellites flying in different orbits around the earth, and information on observation target points corresponding to the selected observation satellite. In the order of sending an orbit change command to lower the orbital altitude of the selected observation satellite, receiving the observation information of the observation target point from the observation satellite after the orbital altitude of the observation satellite is lowered, The observation target point is observed.

According to the present invention, by arranging a plurality of observation satellite groups in different orbits, it is possible to reach the sky over an area requiring emergency observation as quickly as possible using as many observation satellites as possible.
Moreover, the orbital descent from the standby orbit to the low orbit observation orbit makes it possible to observe the situation in the emergency observation area with high observation accuracy.

Further, according to the present invention, the observation satellite having the observation data transmission time within a predetermined time is preferentially selected, so that it reaches the observation target point at the highest speed among the plurality of observation satellites, and is the most It is possible to select observation satellites with excellent data recovery.
In addition, by orbiting the observation satellite step by step, it is possible to select an orbital descent method that can maximize the observation accuracy in order to observe the disaster area in detail.
Furthermore, by providing a data transmission system that relays data, it is possible to prevent the observation satellite that has descended in low orbit from becoming invisible, and to easily perform data transmission by following the satellite speed of the observation satellite. .

Embodiment 1 FIG.
FIG. 1 is a diagram showing the configuration of an observation satellite group control system according to Embodiment 1 of the present invention. FIG. 2 is a diagram showing the configuration of the observation satellite 1, FIG. 2A is a diagram showing the appearance of the observation satellite 1, and FIG. 2B is a block diagram showing the internal configuration of the observation satellite 1. FIG. 3 is a diagram showing the configuration of the satellite information management unit. FIG. 4 is a conceptual diagram showing a plurality of Earth orbits.

  In FIG. 1, the observation satellite group control system includes a plurality of observation satellites 1, a satellite information management unit 2, and a tracking control unit 3. As shown in FIG. 1, each observation satellite 1 is distributed and arranged on a plurality of different standby orbits orbiting the earth 100 to constitute an observation satellite group 10. Each observation satellite 1 can move to an observation orbit located in a low orbit around the earth 100 as shown in FIGS. The observation satellite 1 can autonomously execute the operation command in accordance with the operation command transmitted from the tracking control unit 3.

  In FIG. 2A, each observation satellite 1 has an observation sensor 12 such as an imaging device or a synthetic aperture radar (SAR) mounted on a satellite structure 11. Each observation satellite 1 includes a satellite panel 11, a solar cell panel 13, a thruster 14, and a communication antenna 15. The communication antenna 15 is a directional antenna that performs intersatellite communication or satellite communication with a ground station.

  In FIG. 2 (b), the satellite structure 11 contains onboard equipment such as a power supply unit 16, a position and orientation control unit 17, a communication control unit 21, a control unit 22, a storage unit 23, and an attitude control actuator 20. The The observation satellite 1 includes a battery module having a battery and performing power storage control, a power supply control device, and the like, and includes a power supply unit 16 connected to the solar cell panel 13. The power supply unit 16 supplies power to each satellite-mounted device mounted on the satellite structure 11. The observation satellite 1 includes a position / orientation control unit 17 for controlling the orbital position and attitude of the satellite, an attitude detection sensor 18 and a position detection sensor 19. The position / orientation control unit 17 controls the attitude control actuator 20 and the thruster 14. As the attitude control actuator 20, a momentum wheel, an attitude control thruster, or the like is used. As the attitude detection sensor 18, an earth sensor, a star sensor, an inertial sensor, or the like is used. As the position detection sensor 19, a GPS receiver, an inertial sensor, or the like is used. The observation satellite 1 includes a communication control unit 21 that is connected to the communication antenna 15 and includes a transceiver and a data handling device. The control unit 22 incorporates a clock and is connected to the storage unit 23. The control unit 22 controls the power supply unit 16, the position / orientation control unit 17, the communication control unit 21, and the observation sensor 12, and integrally manages the functions of the entire satellite. The observation satellite 1 has a minimum satellite operation function capable of operating an observation sensor having a desired accuracy and maintaining orbits, changing orbits, changing attitudes, and communicating in outer space. It is desirable to make the size as small as possible so that the size is less than 1 m cubic.

  In FIG. 3, the satellite information management unit 2 includes an input / output device 25 that constitutes a man-machine interface, a control device 26, a satellite database 27, and a geographic database 28. The input / output device 25 includes an input terminal such as a keyboard and a mouse, and a display device such as a CRT, a liquid crystal display, and a display panel. The control device 26 is composed of a personal computer, a dedicated computer equipped with a CPU, and the like, and is connected to the storage device 29. The satellite database 27 stores the physical information (physical parameters for specifying the orbit) of the standby orbit possessed by each observation satellite 1 constituting the observation satellite group 10, the current position data of each observation satellite 1 on the standby orbit, and the like. Is stored. The geographic database 28 stores geographic information on specific areas on the ground and countries around the world, position coordinates of a three-dimensional map, and the like. The satellite information management unit 2 can manage a group of observation satellites to be operated, and can manage which observation satellite is given what operation command.

In FIG. 2, the tracking control unit 3 includes a ground station antenna 31 and a data relay satellite 32. The ground station antenna 31 is connected to the satellite information management unit 2 via a communication network line. The ground station antenna 31 exchanges data with the data relay satellite 32 through a satellite communication line. The data relay satellite 32 performs data transmission with each observation satellite 1 by inter-satellite communication. The data relay satellite 32 has a directional antenna for tracking, and the directional antenna is controlled so that the directional antenna is continuously directed to the designated observation satellite 1 to track the observation satellite 1. The data relay satellite 32 has an omni antenna, and performs data transmission with the ground station antenna 31 using the omni antenna. The ground station antenna 31 has a directional antenna for tracking, and the directional direction of the directional antenna is controlled so that the directional antenna is continuously directed to the data relay satellite 1 to track the data relay satellite 32. A communication unit such as a communication antenna mounted on the ground station antenna 31 and the data relay satellite 32 constitutes a data transmission system for performing data relay. The tracking control unit 3 can transmit an operation command to the observation satellite and acquire necessary information and observation data from the observation satellite.
In the following description of this embodiment, an example in which data transmission is performed with the observation satellite 1 via the data relay satellite 32 will be described. However, when the observation satellite 1 is visible from the ground station antenna 31. Needless to say, various data transmissions may be performed directly between the ground station antenna 31 and the observation satellite 1.

Here, an outline of the operation in the observation satellite group control system will be described.
Usually, the observation satellite group 10 orbits the earth on a standby orbit 200 assigned to each observation satellite 1 in advance and is on standby (hereinafter, this standby state is referred to as standby). . A method for putting each observation satellite 1 into the standby orbit will be described later.

  When a natural disaster such as an earthquake or tsunami, a large-scale disaster such as a fire, an explosion in a power plant or factory, or a collapse of a building occurs, it is necessary to urgently observe the disaster occurrence area within a predetermined time. By analyzing the observation data such as images and location information of the disaster occurrence area (stricken area) in detail, it is possible to accurately grasp the scale of the disaster and the situation of the disaster, and to take appropriate disaster countermeasures immediately. It is. When some kind of emergency occurs like this large-scale disaster, the emergency observation area 50 to be urgently observed is determined by the person in charge of disaster countermeasures, and the approximate position is designated. The observation satellite group control system has a main mission of observing a specific emergency observation area 50 within a predetermined time and acquiring a captured image of the emergency observation area.

[Establishing an emergency observation plan]
When the emergency observation area 50 is determined, the person in charge of planning appointed as the manager in charge interacts with the control program stored in the controller 26 of the satellite information manager 2 through the input / output device 25. At this time, the geographic database 28 is accessed to acquire the geographic information of the emergency observation area 50, and the observation target point in the emergency observation area 50 is set and input. The observation target point is set to, for example, the central position of the emergency observation area 50 or a representative point that is relatively easy to determine the image within the emergency observation area 50. In addition, the person in charge of planning accesses the observation satellite database 27 to acquire information on the observation satellites, and selects the observation satellites such as the time required from the start of the observation execution to the acquisition of the observation data and the observation accuracy. Enter the condition. The satellite information management unit 2 makes an observation plan based on this input information. The satellite information management unit 2 selects the observation satellite 1 that is most suitable for observation in the emergency observation area 50 from the observation satellite group 10 based on the observation satellite selection conditions, and inputs / outputs information on the selected observation satellite 1 Display on the device 25. The person in charge of planning issues input instructions such as orbit change instruction information and operation instruction information corresponding to the selected observation satellite 1 through the input / output device 25. The operation instruction information includes instruction information such as observation time, observation sensor setting conditions, number of observations, presence / absence of orbit return operation, presence / absence of on-orbit disposal. The satellite information management unit 2 makes an emergency observation plan based on this input instruction. The emergency observation plan includes observation target points and their position coordinates in the emergency observation area 50, a data transmission plan of observation data, an orbit change command for the selected observation satellite 1, and information for specifying the selected observation satellite 1 (designation) Satellite information) and operational conditions. The processing flow of the emergency observation plan planning process and the optimal observation satellite selection method will be described again in the second and third embodiments.

  The data transmission plan of the observation data includes a data transmission time (command transmission time) at which the ground station antenna 31 transmits data, a control sequence for the data relay satellite 32 to perform data relay, and the observation satellite 1 reaches the observation target point. Various plans such as the arrival time and the data transmission time (observation data transmission time) at which the observation satellite 1 transmits the observation data are negotiated. The orbit change command includes orbit control information necessary for changing the orbit until the selected observation satellite 1 is moved from the standby orbit to the observation descent after the descent for performing the observation. For example, the trajectory change command includes information such as the injection start time of the thruster 14, the injection amount of the thruster 14, the posture direction at the time of thruster injection, the scheduled time after movement, and the planned position coordinates thereof. The designated satellite information includes an ID code for identifying the satellite, and a different ID code is assigned to each observation satellite constituting the observation satellite group 10. The operation conditions include setting information such as observation time, zoom ratio and exposure amount of the observation sensor, and instruction information such as the number of observations and presence / absence of on-orbit disposal.

[Command data transmission]
The satellite information management unit 2 transmits the designated satellite information, the orbit change command, the observation target point and observation data transmission plan, and the emergency observation command data including the operation conditions based on the set emergency observation plan to the ground station antenna. 31. The ground station antenna 31 transmits emergency observation command data sent from the satellite information management unit 2 to the data relay satellite 32. The data relay satellite 32 transmits the emergency observation command data including the observation target point and the observation data transmission plan to the observation satellite 1 designated by the designated information as the emergency observation command. The observation satellite 1 stores the emergency observation command data included in the emergency observation command in the storage unit 23 through the communication control unit 21.

[Orbital descent]
At the time of standby, the observation satellite 1 is arranged in the earth orbit 200 having an orbital altitude of about 600 km as a standby orbit (for example, reference numeral 1a in FIG. 1). When the observation satellite 1 receives the emergency observation command from the data relay satellite 32, the observation satellite 1 compares the ID code included in the designated satellite information in the received command with the ID code stored in the storage unit 23 in advance. Based on this comparison result, it is confirmed whether or not it is the selected observation satellite. As a result, if the two ID codes match and the self is the selected observation satellite, all the normal observation processes that have been normally performed using the observation sensor 12 are stopped. At the same time, based on the observation data transmission plan, the controller 22 drives the thruster 14 to autonomously lower its orbital altitude. At this time, the observation satellite 1 descends the orbital altitude to an observation orbit 201 that orbits the earth with an orbital altitude of about 200 km, for example (reference numeral 1b in FIG. 1). Note that this orbital descent operation may be performed stepwise over a plurality of times. Details of the step-by-step orbital descent will be further described in the third embodiment.

[Emergency observation]
The observation satellite 1 performs emergency observation that autonomously observes the designated observation target point based on the emergency observation command data stored in advance in the storage unit 23 after the orbit descends to the observation orbit (for example, FIG. 1 code 1c). At this time, the control unit 22 sets observation conditions of the observation sensor 12 such as an observation time and a zoom ratio based on the emergency observation command data. Further, the control unit 22 controls the position / orientation control unit 17 based on the emergency observation command data to control the orbital position and orientation of the observation satellite 1 and at a predetermined position at a predetermined position at a predetermined position. Execute observation at the observation point. At this time, the observation satellite 1 uses the observation sensor 12 to acquire an image of an observation point on the ground using an imaging device, a synthetic aperture radar, or the like.
After performing one observation, the observation satellite 1 transmits the observation data to the data relay satellite 32 based on the designated observation data transmission plan (for example, reference numeral 1d in FIG. 1). The data relay satellite 32 transmits the data received from the observation satellite 1 to the ground station antenna 31. This makes it possible to transmit data to the earth at a higher speed in the event of an emergency. At this time, it is preferable that the observation satellite 1 appropriately controls the attitude so that the communication antenna 15 faces the direction of the data relay satellite 32.

  When the observation satellite 1 is lowered to an observation orbit with an orbital altitude of 200 km, the observation accuracy, that is, the resolution of the observed image, is about three times that when navigating a standby orbit with an orbital altitude of about 600 km. Get higher. This makes it possible to perform highly accurate observation from a low orbit observation orbit using a lens having a small aperture. For example, a case where an image with a resolution of 50 cm to 1 m is photographed using an observation satellite 1 using a line sensor of 1000 pixels and an objective lens having a diameter of about 30 cm to 50 cm will be described. In this case, 1000 images are obtained at 1 m intervals in one observation time (for example, 30 seconds) by gradually changing the viewing angle of the observation sensor as the observation satellite 1 moves on the observation orbit. Then, 1000 m square (observation width 1 km) can be observed by one observation (one shot).

  Of course, the observation satellite 1 can observe a plurality of times. Although the observation cycle of one round varies depending on the latitude of the observation point, as shown in FIG. 4, at the high latitude (south pole or near the north pole), the polar spot satellite 210 can observe the same spot every round. Is possible. In this case, since the time for one round is 5309 seconds (88.5 minutes) at an altitude of 200 km, the same point can be observed several times a day. In the case of low latitude, the observation period becomes irregular depending on the regression period as it approaches the equatorial orbit 220, and in some cases, it may be difficult to observe the same point multiple times. However, depending on the observation trajectory, there are cases where the observation can be performed at least twice, the timing when approaching the observation point in the sky and the timing when moving away from the observation point.

  After the observation satellite 1 designated by the designated satellite information ends transmission of observation data, the person in charge of plan management of the satellite information management unit 2 determines whether the observation satellite 1 can return to the original standby orbit. Judging.

[Return to orbit]
As a result of this determination, when the observation satellite 1 can return to the original standby orbit, the observation satellite 1 moves from the observation orbit and returns to the standby orbit. This return operation is executed based on an input instruction for instructing the return operation to the satellite information management unit 2 by the person in charge of plan management. The satellite information management unit 2 transmits instruction information (orbit return instruction) instructing the return operation to the observation satellite 1 via the ground station antenna 31 and the data relay satellite 32. The observation satellite 1 receives this orbit return instruction and executes a return operation. At this time, the satellite information management unit 2 designates a standby orbit in which the observation satellites 1 are arranged so that the arrangement intervals with the other observation satellites 1 are not dense based on the input instruction of the person in charge of plan management. Information on the designated standby orbit is transmitted to the observation satellite 1 through the ground station antenna 31 and the data relay satellite 32. The observation satellite 1 drives the thruster 14 and moves to the designated standby orbit.

  On the other hand, if it is impossible to return to the original standby orbit, the observation satellite 1 is discarded on the orbit. The satellite information management unit 2 transmits instruction information indicating whether or not the on-orbit disposal process is autonomously performed to the observation satellite 1 as operation conditions in advance via the ground station antenna 31 and the data relay satellite 32. deep. The observation satellite 1 stores instruction information indicating whether orbital disposal is possible in the storage unit 23.

[Disposal on orbit]
Based on this instruction information, the observation satellite 1 is autonomous, if orbital discard is permitted in advance, and if the orbit return instruction from the ground station antenna 31 does not come even after a predetermined time has elapsed after transmission of observation data, Perform on-orbit disposal. In this case, the observation satellite 1 discards the fuel mounted on the satellite and performs low wave processing to prevent unnecessary radio waves from being output to communication devices such as the communication antenna 15 and the communication control unit 21. A pyrotechnic (powder) provided in advance is ignited to crush the battery in the power supply unit 16. As a result, the observation satellite 1 substantially stops functioning, the orbital altitude gradually decreases as it goes around the orbit, and eventually burns out in the atmosphere.

  Note that only the on-orbit discarding operation may be performed on the observation satellite 1 without performing the standby operation of the orbit return instruction. In this case, it is not necessary to determine whether or not the observation satellite 1 can return to the orbit on the ground. After the observation satellite 1 performs the observation, the observation satellite 1 autonomously orbits without waiting for an orbit return instruction from the ground. Execute top disposal. As a result, the observation satellite group control system can be configured more simply, and the operation plan in the satellite information management unit 2 can be simplified.

In addition, depending on the observation orbit such as a polar orbit, a plurality of repeated observations may be performed on the observation orbit before the discard on the orbit is executed.
For example, the person in charge of planning in the satellite information management unit 2 determines whether or not the observation satellite 1 that has fallen into the observation orbit is to continue observation repeatedly.

  As a result of this determination, when iterative observation is determined, the satellite information management unit 2 creates a transmission plan for observation data, and input instruction information for instructing repetitive operation is transmitted via the ground station antenna 31 and the data relay satellite 32. Transmitted to the observation satellite 1. Each time the observation satellite 1 orbits the observation orbit while periodically orbiting the observation orbit, it repeatedly performs observation based on the observation data transmission plan. In this case, the observation data transmission path and the control operation are the same as those described above.

Next, the orbit insertion of the observation satellite group 10 will be described.
Each observation satellite 1 is put on a desired standby orbit by simultaneous launching with other satellites by dual launch or simultaneous launching of a plurality of aircraft. When the dual launch is used, it is possible to reduce the launch cost and to decentralize the arrangement trajectory. At this time, it is desirable that the observation satellite 1 be miniaturized as much as possible so that a plurality of satellites can be launched simultaneously by dual launch. Note that it is preferable that the orbital altitudes are slightly different from each other so that the observation satellites 1 do not collide with each other on the standby orbit.

As described above, the observation satellite group control system according to the first embodiment has the following characteristics.
(1) The observation satellite group is an optimal observation satellite that can be placed as quickly as possible over the emergency observation area represented by the affected area by placing multiple observation satellites on different standby orbits. It has a selection function to select.
(2) It has a function of changing the trajectory for observing the emergency observation area with high accuracy by making it wait in a standby orbit during normal times and descending to a low altitude observation orbit in an emergency.
(2) The observation satellite is reduced in size so that multiple launches can be carried out in one launch by dual launch in order to reduce launch costs.
(3) The observation satellite has an autonomous control function for autonomously performing an observation operation after changing the orbit.
(4) It has an instruction / planning function for selecting a specific observation satellite from the observation satellite group and giving the orbit change command, observation command, and data transmission plan to the selected observation satellite.
(5) A data transmission system that performs data transmission and data relay to the selected observation satellite based on the data transmission plan.

By having the above characteristics, the observation satellite group control system according to the first embodiment can obtain the following effects.
(1) By arranging a plurality of observation satellite groups in different orbits, it is possible to reach the sky over the emergency observation area as quickly as possible using as many observation satellites as possible.
(2) Observation accuracy for observing the situation in the emergency observation area in detail can be obtained by orbital descent from the standby orbit to the low orbit observation orbit by changing the orbit.
(3) By launching with dual launch, launch costs when performing satellite observation using a plurality of satellites can be kept as low as possible.
(4) By providing a data transmission system that relays data, it is possible to prevent the observation satellites in low orbit from becoming invisible and to easily perform data transmission following the satellite speed of the observation satellites.

  Note that the observation satellite 1 has the following advantages as compared with the case where the emergency observation area 50 is photographed using an aircraft such as an aircraft or a helicopter.

  First, by conducting observations in low-orbit observation orbits, it is possible to take pictures of undeveloped areas that can only be imaged in orbiting satellite orbits, and in areas affected by other countries. The desired emergency observation area 50 can be observed with high accuracy (a high-resolution image can be obtained). In addition, over a region where urgent observation is required, a plurality of observation satellites 1 are always distributed on standby orbits, and in the event of an emergency, the observation orbits can be quickly lowered into the observation orbit, allowing observations to be performed. Even in the case of observing a long distance place that requires a long travel time, it is possible to observe the desired emergency observation area 50 more quickly and in a short time.

  Secondly, the observation satellite 1 is autonomous regardless of the weather, the presence / absence of the pilot, the ability of the pilot / camera photographer, etc., simply by specifying the observation point of the emergency observation area 50 for the observation satellite 1. It is possible to observe the observation point at the same time, and it is possible to observe the desired emergency observation area 50 more reliably in an emergency.

Embodiment 2. FIG.
FIG. 5 is a diagram showing an emergency observation flow by the observation satellite group management system according to the second embodiment.
In the figure, the observation satellite group management system includes a data setting process of the satellite database 27 (S11), an information acquisition process of individual observation satellites (S12), an orbit prediction process of individual observation satellites (S13), and an individual observation satellite. Normal observation process (S14), communication planning process (S15), emergency observation operation request confirmation process (S16), emergency observation point input process (S17), operational satellite setting process (S18), emergency observation operation process (S19) The disposal operation process (S20) is executed.

  In this process, the satellite information management unit 2 performs data setting processing (S11), individual observation satellite information acquisition processing (S12), individual observation satellite orbit prediction processing (S13), and communication plan planning processing (S13). In S15), the emergency observation operation request confirmation process (S16), the emergency observation point input process (S17), and the disposal operation process (S20), various processes are executed.

  Further, the ground station antenna 31 executes various processes in the data setting process (S11), the normal observation process (S12) of the individual observation satellites, and the communication planning process (S15).

  In addition, the data relay satellite 32 performs data setting processing (S11), individual observation satellite information acquisition processing (S12), communication plan planning processing (S15), operational satellite setting processing (S18), and emergency observation operation processing (S19). ), Various processes are executed.

  The individual observation satellite 1 executes various processes in the individual observation satellite information acquisition process (S12), the individual observation satellite normal observation process (S14), and the emergency observation operation process (S19).

Hereinafter, each process will be described.
In the data setting process S11, data addition of the newly launched observation satellite 1 and data deletion of the observation satellite 1 discarded in orbit are executed to the satellite database 27 through the satellite information management unit 2. In addition, the satellite information management unit 2 inputs an initial communication plan that defines the communication processing procedure, communication time, communication order, etc. during normal operation for each observation satellite 1 set in the satellite database 27. This initial communication plan is transmitted to the data relay satellite 32.

  In the individual observation satellite information acquisition process S12, the data relay satellite 32 establishes communication with the individual observation satellite 1 at the planned time according to the initial communication plan. When the communication is established, the individual observation satellite 1 uses the GPS information measured by the position detection sensor 19 (GPS time received by the GPS receiver, time information of its own clock synchronized with the GPS time, and positioning using the GPS satellite. The measured positioning result and the received data of the GPS receiver) are transmitted to the data relay satellite 32. The data relay satellite 32 transmits the GPS information of the individual observation satellite 1 to the satellite information management unit 2 via the ground station antenna 31. As a result, the satellite information management unit 2 and the observation satellite 1 can mutually confirm the time lag and confirm the position information of the observation satellite 1. Next, the observation information observed by the observation sensor 12 of the individual observation satellite 1 is transmitted to the data relay satellite 32. The data relay satellite 32 transmits the observation information of the individual observation satellite 1 to the satellite information management unit 2 via the ground station antenna 31.

  Next, in the orbit prediction process S13 of the individual observation satellite, the satellite information management unit 2 performs the current orbit prediction in the individual observation satellite 1 based on the GPS information of the individual observation satellite 1.

  Further, the individual observation satellite 1 executes the normal observation process S14 of the individual observation satellite after transmitting the observation information. Thereafter, the individual observation satellite 1 establishes communication with the data relay satellite 32, transmits GPS information to the data relay satellite 32, transmits observation data to the data relay satellite 32, and normal observation processing of the individual observation satellites. Are sequentially executed.

  Next, in the communication planning process S15, the satellite information management unit 2 registers the orbit prediction results of the individual observation satellites 1 in the orbit prediction database (DB). The orbit prediction DB is configured in the storage device 29 of the satellite information management unit 2. The registration information in the orbit prediction DB of each observation satellite 1 is transmitted to the data relay satellite 32 via the ground station antenna 31. The data relay satellite 32 performs communication resource allocation of the satellite group based on the registration information of the orbit prediction DB. Here, the communication resources are allocated so that the communication duty with each individual observation satellite 1 is approximately averaged over the entire observation satellite group. The communication resource allocation result of the satellite group is transmitted to the satellite information management unit 2 via the ground station antenna 31.

  Next, the satellite information management unit 2 confirms whether or not an emergency observation operation request is input in the emergency observation operation request confirmation processing S16. At this time, when the emergency observation request is received, the process proceeds to the emergency observation point input process S17. On the other hand, if there is no emergency observation operation request in the emergency observation operation request confirmation process S16, the data relay satellite 32 is answered that there is no emergency observation operation request, and the process returns to step S11 and the process is repeated.

  When the process proceeds to the emergency observation point input process S <b> 17, the satellite information management unit 2 inputs an observation target point in the emergency observation area and extracts its position coordinates based on the geographic database 28.

  The satellite information management unit 2 causes the data relay satellite 32 to start executing the operation satellite selection process S18 via the ground station antenna 31.

  In the operation satellite selection process S18, the imageable time of the observation target point is calculated. In addition, a plurality of observation satellites 1 that can transmit an emergency observation command are selected. In addition, several observation satellites 1 that can further transmit emergency observation data are selected from the selected observation satellites. Needless to say, in this selection, information may be exchanged with the satellite information management unit 2 as appropriate.

At this time, an observation satellite is selected from the following viewpoints (1) and (2), and an observation satellite 1 that performs emergency observation is determined.
(1) Select an observation satellite that reaches the observation target point at the fastest speed and has the best data recovery.
(2) In order to observe the disaster area in detail, select the orbital descent method with the highest observation accuracy.
Further, when the observation satellite 1 that performs the emergency observation is determined, the satellite that performs the steady observation is also determined at the same time.
The optimum observation satellite 1 selection process will be further described in the third embodiment.

When the observation satellite 1 to be urgently observed is determined, the emergency observation operation of the observation satellite 1 is executed in the emergency observation operation processing S19.
In this process, first, the data relay satellite 32 transmits emergency observation command data including an orbit change command as described in the first embodiment to the observation satellite 1 as an emergency observation command.
Next, when the observation satellite 1 receives the emergency observation command, the observation satellite 1 performs the emergency observation using the observation sensor 12.
After the emergency observation, the observation satellite 1 transmits the observed emergency observation data to the data relay satellite 32.
The data relay satellite 32 transmits the received emergency observation data to the satellite information management unit 2 via the ground station antenna 31.

  Upon receiving the emergency observation data, the satellite information management unit 2 executes the discard operation of the observation satellite 1 that has performed the emergency observation. At this time, in the satellite database 27, the deletion setting of the observation satellite 1 that has performed emergency observation is performed.

  In the second embodiment, the example in which the operation satellite selection process S18 and the emergency observation operation process S19 are executed by the data relay satellite 32 has been described. However, as described in the first embodiment, the observation satellite 1 The selection and operation may be performed by the satellite information management unit 2. In this case, the information determined by the satellite information management unit 2 is transmitted to the observation satellite 1 via the ground station antenna 31 and the data relay satellite 32.

Embodiment 3 FIG.
FIG. 6 is a diagram showing an observation satellite selection processing operation by the observation satellite group management system according to the third embodiment. 6A shows a selection processing flow for selecting an observation satellite to be operated, and FIGS. 6B, 6C, 6D, and 6E are diagrams for explaining each processing routine in the selection processing flow. FIG. FIG. 7 is a diagram for explaining stepwise orbital descent of the observation satellite.

In the following, the observation satellite selection process will be described with reference to FIG.
In the figure, it is assumed that five observation satellites A, B, C, and D are on standby in a standby orbit.
In this case, these observation satellites 1 normally acquire observation data at predetermined observation points at respective orbit altitudes. Each observation satellite 1 transmits satellite information and observation data to the tracking control unit 3 directly or indirectly by data relay at a predetermined time. The tracking control unit 3 receives and records the transmitted observation data. Note that a method for distributing received data to another organization is not described here because it is not the gist of the invention.

  If an emergency observation request for an observation target point P that requires emergency observation occurs, the selection process of the observation satellite 1 is executed by the following procedures (a) to (e) shown in FIG. To implement.

(A) Emergency observation point imaging possible time calculation process S21
First, in the process S21, the arrival time to the observation point is calculated within the required observation time from the issuing of the emergency observation request to the acquisition of the observation data observed urgently. For example, the example shown in FIG. 6B shows that all the observation satellites A to E can reach the observation point within the required observation time.

(B) Emergency observation command transmission possible satellite selection process S22
Next, in process S22, a command transmission possible time during which an operation command (for example, an emergency observation command) of the observation satellite 1 can be transmitted is calculated, and an observation satellite 1 having a command transmission time prior to the above (a) is selected. To do. This condition is that the observation command transmission time zone α and the observation point arrival time β are arranged in the order of α−β. In this case, in the example shown in FIG. 6C, among the observation satellites A to E, the observation satellites A, C, and D satisfy this condition.

(C) Emergency observation data transmission possible satellite selection process S23
Next, in the process S23, after (a) above, the observation data transmission possible time during which the observation data captured by the observation sensor 12 can be transmitted to the ground within the required observation time is calculated, and the observation satellite 1 suitable for these is calculated. select. This conforming condition is that the observation point arrival time β and the observation data transmission time zone γ are arranged in the order of β−γ. In this case, in the example shown in FIG. 6D, the observation satellites A, C, and D satisfy this condition. Here, if it selects from a viewpoint of observation time, it will become possible to perform observation promptly in the order of observation satellites C, A, and D. However, from the viewpoint of obtaining observation data, it is more optimal to select observation satellites in the order of observation satellites A, C, and D. Further, in the observation satellites shown in the first to third embodiments, since the observation satellite is assumed to transition from a standby orbit to a low orbit observation orbit, the observation condition is as close as possible to the sky above the observation target point P. Higher-precision observation is possible. From this point of view, instead of simply performing orbit control, the position of the observation point is adjusted by performing position adjustment by step control and step-by-step orbit control as shown in (d) of the next processing. It is desirable.
In addition, the other observation satellites B and E can often be observed if the time frame is expanded, but here, the observation data acquisition time is limited, and within the predetermined required observation time. The selection in is illustrated.

(D) Emergency observation satellite orbit descent method calculation process S24
Next, in process S24, an optimal adjustment process for reaching the sky above the position of the observation target point is performed. Here, FIG. 6E will be described as an example.
The satellite orbit tends to shift eastward in the longitude direction due to the relationship between the earth rotation speed and the orbital speed when the orbit altitude is lowered. Therefore, the position in the longitude direction differs before and after the orbital descent.
In the example of FIG. 6 (e), the observation target point P is located between the observation position A1 after the orbital descent for the observation satellite A and the standby orbit before the descent, and for the observation satellite C, It is located on the east side of the observation position C1 after the orbital descent. For the observation satellite D, the observation target point P is located on the west side of both the observation position D1 after the orbital descent and the orbit before the orbital descent.

Therefore, in the process S24, the orbit control timing is adjusted for the observation satellites C and D so that the position of the observation point is closest to the observation target point P.
On the other hand, the orbital control maneuver is performed on the observation satellite A so that the position of the observation point is located as close as possible to the sky above the observation target point P by performing the orbital descent stepwise multiple times.

  FIG. 7 is a diagram exemplifying orbital descent timing when orbit control maneuvers are performed by stepping down the observation satellite. In FIG. 6 (e) and FIG. 7, when the observation satellite A descends from the standby orbit to the observation orbit at time t1, the observation satellite A passes the observation position A1. On the other hand, when the orbit descends from the standby orbit to the observation orbit at time t3, the observation position C1 is passed. Further, when the orbit descends from the standby orbit to the middle orbit at time t1, and further descends from the middle orbit to the observation orbit at time t2, it becomes possible to pass immediately above the observation target position P.

(E) Emergency observation execution satellite determination process S25
Next, in process S25, all the observation conditions are compared, and the observation satellite that is most suitable for the observation request is selected.
In the example of FIG. 6, the observation satellite C that can execute observation earliest is the most suitable for obtaining the observation immediacy. Further, if it is necessary to drop data to the ground at the fastest speed, observation satellite A that can transmit observation data to the ground earliest is optimal. Further, when the request for observation accuracy is given priority, the observation satellite A that can approach the observation target point P directly is optimal.

To summarize the above, this embodiment has the following features (1) to (6) in the observation satellite selection method.
(1) An observation command transmission time zone in which an observation command can be transmitted is calculated for each satellite in a plurality of satellite groups.
(2) The observation points and observation point arrival times at which the individual satellites of the plurality of satellite groups reach the struck ground sky are calculated.
(3) An observation data transmission time zone in which observation data after execution of an observation command can be transmitted is calculated for each satellite in the plurality of satellite groups.
(4) The observation command transmission time zone α, the observation point arrival time β, and the observation data transmission time zone γ calculated in (1) to (3) above can be arranged in the order of α-β-γ, and γ Select a satellite whose time zone is within the required time.
(5) In (4) above, the observation target point of the selected satellite is located at a lower latitude than the predetermined latitude, the longitude of the observation target point is located on the east side in the orbit before the orbital descent, and is closest to the observation point When the position is west of the longitude of the observation target point, calculate multiple orbital descent patterns, calculate the optimal orbital descent pattern from the calculated patterns, and use the optimal observation point and optimal observation time with the optimal orbital pattern Is calculated.
(6) Among the optimum observation point and the optimum observation time of the satellite calculated in (5) above, the request is made in accordance with a request order having a high priority among the preset observation time requests or observation accuracy requests. Select the optimal observation satellite that satisfies your needs.

In this embodiment, the following effects can be obtained by selecting the optimum observation satellite from the observation satellite group 10 as described above.
(1) From among a plurality of observation satellites, it is possible to select an observation satellite that reaches the observation target point at the fastest speed and has the best data recovery.
(2) In order to observe the disaster area in detail, it is possible to select an orbital descent method that can maximize the observation accuracy.

Embodiment 4 FIG.
FIG. 8 is a diagram illustrating a data relay system that performs data relay using an air vehicle 33 instead of the data relay satellite 32 described in the first and second embodiments.

  In the figure, the flying object 33 is constituted by an aircraft, an airship, a balloon, or the like, and flies over, for example, an altitude of about 30 to 100 km. At this time, the flying object 33 flies in an area that is visible from the observation satellite 1 in the sky from the periphery of the emergency observation area to the far side. The flying body 33 includes a ground station communication antenna that performs data transmission with the ground station antenna 34 and a satellite communication antenna that performs data transmission with the observation satellite 1. The ground station antenna 34 together with the ground station antenna 31 constitutes the tracking control unit 3 and is connected to the satellite information management unit 2.

  In this embodiment, the ground station antenna 31 communicates with the observation satellite 1 during normal times. In an emergency, an emergency observation command is transmitted to the observation satellite 1 selected for emergency observation via the ground station antenna 31. As a result, the selected observation satellite 1 performs orbital descent and performs emergency observation over the emergency observation area. When the observation is completed, the selected observation satellite 1 transmits the observation data to the flying object 33 after a predetermined time. The flying object 33 transmits the observation data received from the selected observation satellite 1 to the ground station antenna 34. Thereafter, the selected observation satellite 1 is discarded in orbit.

  In this embodiment, since the observation data transmitted from the observation satellite 1 can be relayed using the flying object 33 whose position can be freely moved, even if the data relay satellite is invisible from the observation satellite 1. The observation data can be relayed via the flying object 33. Therefore, an observation satellite group control system with higher mobility can be configured in the operation of observation satellites, and observation data can be transmitted to the ground quickly. In addition, by flying at a low altitude of about 50km from the ground, the number of visible observation satellites is significantly increased compared to when data is relayed between ground stations and observation satellites. A data relay system can be constructed more efficiently than when data is relayed.

Embodiment 5. FIG.
FIG. 9 is a diagram for explaining a data relay system that performs data relay using a plurality of distributed ground station antennas 35 instead of the data relay satellite 32 described in the first and second embodiments.

  In the figure, a plurality of ground station antennas 35 are arranged in advance around an area where emergency observation is required. The ground station antenna 35 includes a satellite communication antenna that performs data transmission with the observation satellite 1. The plurality of ground station antennas 35 constitute the tracking control unit 3 and are connected to the satellite information management unit 2.

  In this embodiment, any one of the ground station antennas 35 visible from the observation satellite 1 normally communicates with the observation satellite 1. In an emergency, one of the ground station antennas 35 that is visible from the observation satellite 1 selected for observation in the emergency observation area is selected, and an emergency observation command is transmitted to the selected observation satellite 1. As a result, the observation satellite 1 performs orbital descent and performs emergency observation over the emergency observation area. When the observation is completed, the selected observation satellite 1 transmits the observation data to the selected ground station antenna 35 after a predetermined time. The ground station antenna 35 transmits the observation data received from the selected observation satellite 1 to the satellite information management unit 2. Thereafter, the selected observation satellite 1 is discarded in orbit.

  In this embodiment, since the observation data transmitted from the observation satellite 1 that has descended orbit using the plurality of ground station antennas 35 can be relayed, even if the data relay satellite is invisible from the observation satellite 1. Data relay of observation data becomes possible. Further, it is not necessary to fly the flying object for data relay, and it is not necessary to urgently dispatch the flying object in an emergency or to keep flying the flying object at all times to prepare for data relay. For this reason, it is possible to configure an observation satellite group control system that can keep the operation cost lower than that when the flying object is always flying, and can stably transmit data in the operation of the observation satellite. .

It is a figure which shows the observation satellite group control system by Embodiment 1 of this invention. It is a figure which shows the observation satellite by Embodiment 1 of this invention. It is a figure which shows the satellite information management part by Embodiment 1 of this invention. It is a conceptual diagram which shows an earth orbit. It is a figure which shows the emergency observation flow of the observation satellite group control system by Embodiment 2 of this invention. It is a figure which shows the selection process of the observation satellite by Embodiment 3 of this invention. FIG. It is a figure which shows the step-orbit descent of the observation satellite by Embodiment 3 of this invention. It is a figure which shows the data relay system by Embodiment 4 which concerns on this invention. It is a figure which shows the data relay system by Embodiment 5 which concerns on this invention.

Explanation of symbols

  Observation satellite 1, satellite information management unit 2, tracking control unit 3, observation satellite group 10, observation sensor 12, thruster 14, communication antenna 15, ground station antenna 31, data relay satellite 32, flying vehicle 33, ground station antenna 34 , A plurality of ground station antennas 35 and an emergency observation area 50.

Claims (15)

Multiple observation satellites flying in different orbits around the earth,
At least one observation satellite is selected from the plurality of observation satellites, information on the observation target point corresponding to the selected observation satellite is transmitted, and an orbit change command for lowering the orbit altitude of the selected observation satellite is transmitted. Satellite information management department,
With
When the observation satellite receives the information on the observation target point and the orbit change command sent from the satellite information management unit, the observation satellite lowers its own orbital altitude and observes the observation target point after the orbital altitude is lowered.
An observation satellite group control system. The observation satellite group control system according to claim 1, wherein the observation satellite is discarded in orbit after transmitting observation data of the observation target point. The satellite information management unit selects, from the plurality of observation satellites, an observation satellite that can descend to an orbit in which the observation target point is visible within a predetermined time. 2. Observation satellite group control system described in 2. It is equipped with a communication unit that performs data transmission with observation satellites.
The satellite information management unit navigates the observation target point and the orbit where the communication unit is visible within a predetermined time in the orbit after the descent from the plurality of observation satellites navigating the orbit where the communication unit becomes visible 4. The observation satellite group control system according to claim 3, wherein an observation satellite to be selected is selected and an orbit change command is sent to the observation satellite via the communication unit. The satellite information management unit calculates, for each observation satellite, a command transmission time for transmitting an orbit change command, an arrival time for reaching the observation target point, and an observation data transmission time for transmitting observation data to the ground. 5. The observation satellites arranged in the order of command transmission time, arrival time, observation data transmission time, and observation data transmission time within a predetermined time are preferentially selected. Observation satellite group control system. 6. The observation satellite group control according to claim 5, wherein the satellite information management unit preferentially selects the observation satellite that is closest to the sky above the observation target point for each observation satellite. system. 2. The satellite information management unit descends orbits the observation satellite stepwise so that the observation point that performs the observation is closest to the sky above the observation target point with respect to the selected observation satellite. The observation satellite group control system according to claim 5. 5. The observation satellite group control system according to claim 4, wherein the communication unit is mounted on a data relay satellite or a flying body and relays data between the observation satellite and the ground. Flying in an orbit around the Earth different from other observation satellites and receiving information on the observation target point from the satellite information management department, the own orbital altitude is lowered and the observation target point is observed after the orbital altitude is lowered An observation satellite characterized by transmitting observation data at an observation target point and discarding it in orbit after transmitting the observation data. An observation sensor that acquires an observation image, a thruster that descends the orbital altitude, a communication antenna, and a control unit,
The control unit activates the thruster to lower its orbital altitude when receiving information on the observation target point from the satellite information management unit while flying in a different orbit around the earth than the other observation satellites.
After the orbital altitude descent, the control unit performs observation of the observation target point by the observation sensor,
An observation satellite characterized in that the control unit transmits observation data of an observation target point by the communication antenna after execution of observation. 11. The observation satellite according to claim 9 or 10, wherein the control unit executes discarding on its own orbit after transmitting observation data. An observation satellite that is orbitally controlled by the observation satellite group control system according to any one of claims 3 to 8. At least one observation satellite is selected from a plurality of observation satellites that fly in different orbits around the earth, and information on the observation target point corresponding to the selected observation satellite is transmitted. A satellite information management unit that sends out a trajectory change command to descend;
A communication antenna for transmitting the observation target point information and the orbit change command sent from the satellite information management unit to the selected observation satellite directly or via a data relay satellite or flying object;
With
The communication antenna receives observation information of an observation target point from the observation satellite after the orbital altitude of the observation satellite is lowered, either directly or via a data relay satellite or flying object.
A ground station characterized by that. A ground station for performing orbit control of an observation satellite using the observation satellite group control system according to any one of claims 3 to 8. Selecting at least one observation satellite from a plurality of observation satellites flying in different earth orbits;
Sending information on the observation target point corresponding to the selected observation satellite and sending an orbit change command to lower the orbit altitude of the selected observation satellite;
Receiving observation information of an observation target point from the observation satellite after the orbital altitude of the observation satellite is lowered;
Observation satellite group control method characterized by observing the observation target point in the order of.

Images