Deorbiting device and information processing system

Abstract

Provided is a deorbiting device or the like capable of detecting environmental information indicating the environment in space at various altitudes in space at a low cost. A deorbiting device according to one aspect of the present invention is attached to an object moving in orbit in space, the deorbiting device comprising: a resistance force generation unit that generates a resistance force with respect to the movement of the object in orbit; a detection unit that detects environmental information indicating a prescribed environment during the generation of the resistance force by the resistance force generation unit; a storage unit; and an environmental information processing unit that stores the environmental information in the storage unit.

Description

Deorbit device and information processing system

[0001] The present invention relates to a deorbiting device and an information processing system.

[0002] In space development, understanding the environment of outer space is an important issue. For example, Patent Document 1 describes a detection sheet to be mounted on a spacecraft orbiting the Earth. The detection sheet includes a thin insulating film, a detection wire attached to the thin film that breaks when hit by an object floating in space, and a detection circuit for detecting the breakage of the detection wire.

[0003] Patent No. 5492568

[0004] However, in space, the environment, including gravity, radiation distribution, and atmospheric density, changes depending on the altitude of the orbit. Since spacecraft usually orbit at a fixed altitude, in order to understand the environment at various altitudes, measurements must be taken using multiple spacecraft at orbits with different altitudes, which would be extremely costly.

[0005] Therefore, an object of the present invention is to provide an orbital deorbiting device and the like that is capable of detecting environmental information indicating the environment in space at various altitudes in space at low cost.

[0006] An orbital de-orbit device according to one aspect of the present invention is an orbital de-orbit device attached to an object moving in an orbit in outer space, and includes a resistance force generating unit that generates resistance to the object's movement in its orbit, a detection unit that detects environmental information that indicates a predetermined environment in outer space while the resistance force is being generated by the resistance force generating unit, a memory unit, and an environmental information processing unit that stores the environmental information in the memory unit.

[0007] According to this aspect, the resistance generating unit generates a resistance force against the movement of the object on the orbit, causing it to leave the orbit, while the detection unit detects environmental information indicating the environment in outer space.

[0008] According to the present invention, it is possible to provide a deorbiting device and the like that is capable of detecting environmental information that indicates the environment in outer space at various altitudes in outer space at low cost.

[0009] 1 is a schematic diagram showing a state in which the de-orbital device 3 is mounted on a spacecraft 2. FIG. 2 is a schematic diagram showing another state in which the de-orbital device 3 is mounted on a spacecraft. FIG. 3 is a block diagram showing an example of the functional configuration of the de-orbital device 3. FIG. 4 is a schematic diagram showing an example of the configuration of a debris sensor 39 provided on the tether 31. FIG. 5 is a functional block diagram showing an example of the functional configuration of the control device 36. FIG. 6 is a schematic diagram showing an example of a cross-section perpendicular to the longitudinal direction of a modified example of the tether 31 provided on the de-orbital device 3. FIG. 7 is a schematic diagram showing an example of a cross-section perpendicular to the longitudinal direction of a modified example of the tether 31 provided on the de-orbital device 3. FIG. 8 is a schematic diagram showing an example of a cross-section perpendicular to the longitudinal direction of a modified example of the tether 31 provided on the de-orbital device 3. FIG. 9 is a schematic diagram showing an example of a cross-section perpendicular to the longitudinal direction of a modified example of the tether 31 provided on the de-orbital device 3. 1 is a schematic diagram showing an example of a rocket 100. FIG. 2 is a schematic diagram showing an example of the configuration of a mapping system 200 according to another embodiment.

[0010] A preferred embodiment of the present invention will be described with reference to the accompanying drawings (in each drawing, the same reference numerals denote the same or similar configurations).

[0011] (1) Overall Configuration of De-orbit Device 3 The overall configuration of the de-orbit device 3 according to this embodiment will be described with reference to Figures 1 to 3. Figure 1 is a schematic diagram showing a state in which the de-orbit device 3 is mounted on a spacecraft 2. Figure 2 is a schematic diagram showing another state in which the de-orbit device 3 is mounted on a spacecraft. Figure 3 is a block diagram showing an example of the functional configuration of the de-orbit device 3. In Figures 1 to 3, the direction of travel of the spacecraft 2 (the direction of the orbit around the Earth, etc.) is defined as the X-axis, the horizontal direction perpendicular to the X-axis is defined as the Y-axis, and the direction perpendicular to the X-axis and Y-axis is defined as the Z-axis.

[0012] The spacecraft 2 is an example of an object to which the orbital departure device 3 is attached, and moves in outer space in an orbit around the Earth or the like. The spacecraft 2 is not particularly limited as long as it is an object that moves in an orbit, and may include an artificial satellite, a rocket, a space station, or parts of them. The altitude of the orbit is not particularly limited, but may be, for example, about 200 to 1000 km. Furthermore, the spacecraft 2 rotates at various rotational speeds and directions while moving in the orbit. Furthermore, for attitude control of the spacecraft 2, a device such as a reaction wheel that rotates at a predetermined rotational speed around a predetermined rotation axis may be provided.

[0013] The de-orbital device 3 is attached to the spacecraft 2 and generates resistance to the movement of the spacecraft 2 in its orbit, thereby causing the spacecraft 2 to de-orbit. The de-orbital device 3 is also configured to be able to detect environmental information indicating a specific environment in space while the resistance is being generated. To this end, the de-orbital device 3 includes a tether 31, a storage unit 33, a gas supply unit 34, an electromagnetic valve 35, a control device 36, a communication device 37, a power supply unit 38, and a debris sensor 39.

[0014] The tether 31 is an example of a resistance force generating unit that generates resistance to the movement of the spacecraft 2 on its orbit. The tether 31 may be configured to form a predetermined shape. The predetermined shape is not particularly limited, but may be, for example, a three-dimensional shape such as a cylindrical shape described below, or a flat shape whose thickness is negligibly small compared to its longitudinal dimension.

[0015] The tether 31 may have an inflatable structure and, for example, may be configured to expand and form a predetermined shape when gas is supplied thereto from a gas supply unit 34. The tether 31 may be formed, for example, from one or more flexible thin film members. The tether 31 may have, for example, overlapping portions where multiple thin film members are bonded together. The overlapping portions may also serve as areas that receive atmospheric resistance. Materials constituting the thin film members may include, for example, resin, adhesive, carbon fiber reinforced plastics (CFRP), carbon film, etc. Furthermore, the thin film member may be configured to include one or more conductive materials, such as metal fibers (e.g., aluminum), high-strength conductive fibers, and metal thin films, or may be configured by laminating the conductive materials. As a result, a Lorentz force is generated on the tether 31 moving through space, and this Lorentz force functions as a resistance force against the movement of the spacecraft 2 in the orbit in addition to or instead of atmospheric resistance. Note that, as will be described later, when a debris sensor 39 is provided on at least a part of the tether 31, the tether 31 may be made of a thin film made of an insulating material.

[0016] One end of the tether 31 may be configured as a fixed end 31T fixed inside the housing of the orbital de-orbit device 3, and the other end may be configured as a free end 31F not fixed inside the housing of the orbital de-orbit device 3. The orbital de-orbit device 3 is configured to be able to store the tether 31 therein during the mission of the spacecraft 2, for example, as shown in FIG. 2 . The orbital de-orbit device 3 is also configured to be able to release the free end 31F of the tether 31 into space and supply a predetermined gas into the inside of the tether 31 at a predetermined timing, such as when the mission of the spacecraft 2 ends, thereby expanding the tether 31 and deploying it to form a predetermined shape. FIG. 1 shows a state in which the tether 31 is deployed outside the housing of the orbital de-orbit device 3. When deployed, the tether 31 is configured to be tiltable about the Z-axis with the housing of the orbital de-orbit device 3 as the base point. 1, the direction of the tether 31 is drawn parallel to the Z axis, but the tether 31 is configured to be tiltable at a predetermined angle with respect to the Z axis, with the housing of the de-orbital device 3 as the base point, depending on the gravitational gradient force, atmospheric resistance, etc. The area of ​​the tether 31 is not particularly limited, but may be larger than the target object, such as the spacecraft 2, to which the de-orbital device 3 is attached, for example.

[0017] The predetermined shape formed by the deployed tether 31 may be a shape capable of withstanding atmospheric resistance to release the spacecraft 2 from orbit. The predetermined shape may be, for example, a shape with high isotropy about the longitudinal direction of the tether 31 (the Z-axis direction in FIG. 1 ). The higher the isotropy about the longitudinal direction of the tether 31 (the Z-axis direction in FIG. 1 ), the smaller the variation in atmospheric resistance experienced when the tether 31 rotates around that axis. Therefore, rotation of the tether about that axis is less likely to occur, the orientation of the tether about the longitudinal direction is stabilized, and it is easier to ensure a projected area for withstanding atmospheric resistance regardless of the orientation about the longitudinal direction. A shape with high isotropy about the longitudinal direction of the tether 31 (the Z-axis direction in FIG. 1 ) may be, for example, a substantially cylindrical shape as shown in FIG. 1 . In this case, the longitudinal dimension of the tether 31 is not particularly limited and may be, for example, in the range of several meters to several kilometers.

[0018] A gravity gradient force may act on the tether 31. Here, the gravity gradient force is a force that acts to orient the attitude of an object in a predetermined direction due to spatial changes in the gravitational acceleration acting on the object. In particular, when an object that revolves around the center of gravity, such as the Earth, has a long shape like the tether 31, the gravity gradient force acts as a force that orients the longitudinal direction toward the center of gravity, that is, a force that reduces the angle between the longitudinal direction and the Z-axis direction.

[0019] The larger the longitudinal dimension of the tether 31, the more easily the gravitational gradient force acts on it, and as a result, it is more likely to orient toward the zenith (facing away from the center of the Earth) or the geocentric (facing toward the center of the Earth). The tether 31 according to this embodiment may have dimensions such that the longitudinal direction of the deployed tether 31 is controlled toward the zenith or the geocentric by the gravitational gradient force it receives. Specifically, when the longitudinal dimension of the three-dimensional shape of the tether 31 is L and the lateral dimension is W, the aspect ratio (L / W) may be set to a predetermined threshold or greater so that the tether 31, whose longitudinal direction is oriented toward the zenith or the geocentric, does not tilt to a predetermined angle even due to atmospheric resistance. As a result, the tether 31 does not tilt until its longitudinal direction forms the predetermined angle θ with the Z axis, and its attitude in which it is subjected to atmospheric resistance is passively maintained, enabling it to withstand large atmospheric resistance for deorbiting.

[0020] For example, the storage section 33 may be configured to have a space therein capable of storing the tether 31. The manner in which the tether 31 is stored inside the storage section 33 is not particularly limited, but may be, for example, wound as shown in Fig. 3, or folded.

[0021] The gas supply unit 34 may hold a gas to be supplied to the tether 31. The gas supply unit 34 may be configured as, for example, a gas cartridge. The type of gas to be supplied to the tether 31 is not particularly limited, and may be, for example, nitrogen gas.

[0022] The electromagnetic valve 35 may be connected to each of the gas supply unit 34 and the tether 31. The electromagnetic valve 35 may adjust the opening and closing based on a control signal received from the control device 36, thereby adjusting the amount of gas supplied from the gas supply unit 34 to the tether 31.

[0023] One end 31T of the tether 31 may be configured as a fixed end that is fixed to a predetermined position on the housing of the orbital departure device 3. The end 31T of the tether may be connected to the gas supply unit 34 via an electromagnetic valve 35. The other end 31F of the tether 31 may be configured as a free end that is not fixed to the housing of the orbital departure device 3. The tether 31 may be stored inside the storage unit 33, for example, during a mission of the spacecraft 2.

[0024] The debris sensor 39 is provided on at least a portion of the tether 31. The debris sensor 39 is an example of a detector that detects environmental information in outer space. Under the control of a control unit 361 (environmental information processing unit 361b, etc.) described below, the debris sensor 39 detects collisions of debris, which is an example of an object floating in space, as an example of environmental information. There are no particular limitations on the size of debris that the debris sensor 39 can detect, but it may include, for example, debris with a diameter of 1 mm or less, or debris with a diameter of 50 μm or less. The debris sensor 39 may be provided on at least a portion of the tether 31. By providing the debris sensor 39 on at least a portion of the tether 31, it is possible to ensure an area for the debris sensor 39.

[0025] The configuration of the debris sensor 39 provided on the tether 31 will be described with reference to FIG. 4 . The debris sensor 39 is provided, for example, on the outer surface of the tether 31. The debris sensor 39 may be configured to include a large number of detection lines 39La, 39Lb provided at a predetermined arrangement pitch (spatial period) on a thin insulating film that constitutes the tether 31. The detection line 39La extends in the longitudinal direction of the tether 31, and the detection line 39Lb extends in the lateral direction of the tether 31. Note that the debris sensor 39 may include only one of the detection line 39La extending in the longitudinal direction of the tether 31 and the detection line 39Lb extending in the lateral direction of the tether 31. The detection lines 39La and 39Lb may be insulated from each other. A detection circuit (not shown) is connected to each of the detection lines 39La, 39Lb in the debris sensor 39. The detection circuit detects whether each detection line 39La, 39Lb is conductive and supplies a detection signal based on this detection to the control device 36. When debris collides with one of the detection lines 39La, 39Lb and breaks that detection line 39La, 39Lb, that detection line 39La, 39Lb becomes non-conductive. Therefore, when the detection signal corresponding to a certain detection line 39La, 39Lb indicates non-conduction, the control device 36 can determine that debris has collided with one of the detection lines 39La, 39Lb, causing a break. Note that the detection lines 39La, 39Lb may be collectively referred to as detection lines 39.

[0026] The arrangement pitch (spatial period) of the detection lines 39La, 39Lb may be set to a value corresponding to the particle size of the object floating in space that is desired to be detected. As a specific example, if it is desired to detect an object floating in space with an effective diameter of approximately 100 μm or more, the debris sensor 39 may be configured such that 50 μm-wide copper foil detection lines 3 are arranged in parallel at 50 μm intervals on one side of a thin film of a tether 31 made of a material such as polyimide and having a thickness of approximately 50 μm, using a technique such as etching, so that the arrangement pitch of the detection lines 39La, 39Lb is 100 μm, which corresponds to the minimum particle size that is the detection limit for the object floating in space. In such a debris sensor 39, when an object floating in space with an effective diameter of 100 μm or more collides with the debris sensor 39, one or more of the detection lines 39L arranged on one side of the debris sensor 39 will be broken.

[0027] The debris sensor 39 detects information related to debris collisions as an example of environmental information. The debris sensor 39 may detect the position of the debris collision or the dimensions of the colliding debris, for example, based on which of the detection lines 39L has broken. The debris sensor 39 may also detect the time of the debris collision based on the time the detection line 39L breaks. Note that the time may be generated by an internal clock (not shown) included in the de-orbit device 3, or may be obtained from an external source via the communication unit 37.

[0028] For example, the debris sensor 39 may treat multiple breaks in the detection line 39L as breaks caused by successive collisions of a single piece of debris under predetermined conditions. The predetermined conditions may include, for example, the occurrence of multiple breaks within a period of less than a predetermined length. The debris sensor 39 may detect the direction of debris collision based on the locations of such multiple breaks. Specifically, if the detection line 39L is broken at a first position and a second position, the debris sensor 39 may detect the direction including the first position and the second position as the direction of debris collision.

[0029] When the tether 31 has an inflatable structure, the thin film that constitutes the tether 31 is arranged around the gas filled inside the tether 31. Therefore, when the debris sensor 39 is provided on at least a part of the tether 31 that has an inflatable structure, the multiple detection points included in the debris sensor 39 are also arranged around the gas filled inside the tether 31, making it easier to maintain the distance between the detection points. This improves the accuracy with which the debris sensor 39 detects information related to debris collisions.

[0030] The de-orbit device 3 may include a sensor that detects the orientation of the tether 31. The sensor may supply a detection signal indicating the orientation of the tether 31 to the control unit 36. The environmental information processing unit 361b of the control unit 36 ​​may take into account the detection signal indicating the orientation of the tether 31 obtained from the sensor when calculating the direction of debris collision. For example, the environmental information processing unit 361b may correct the direction calculated based on the rupture position in the debris sensor 39 using the orientation of the tether 31 indicated by the detection signal.

[0031] As described above, the tether control unit 361a may deploy the tether 31 so as to maintain a constant ratio between the altitude descent rate of the de-orbital device 3 (spacecraft 2) and the deployment rate of the tether 31. In this case, the environmental information processing unit 361b may use only the portion of the debris sensor 39 that has not yet been broken by a debris collision, i.e., the portion newly deployed by the tether control unit 361a, for debris detection. According to this aspect, as the altitude of the de-orbital device 3 descends, the portion of the debris sensor 39 that has not substantially been broken by a debris collision can be used for debris detection, improving debris detection accuracy.

[0032] The position sensor 40 is an example of a position acquisition unit that acquires position information indicating a position associated with an environment (a predetermined environment in outer space) detected by a detection unit such as the debris sensor 39. Note that the position information indicating the position of the de-orbiting device 3 may include information indicating the position of the spacecraft 2.

[0033] The position sensor 40 may acquire, as the position information, for example, the altitude of the de-orbit device 3 when the debris collides with the debris sensor 39. The method by which the position sensor 40 acquires this altitude is not particularly limited, but may include, for example, measuring the time it takes for radar waves transmitted from the position sensor 40 toward the Earth's surface to be reflected by the Earth's surface and return, calculating the altitude based on GPS signals received from multiple GPS satellites, or calculating the altitude based on a measured gravitational field of the Earth.

[0034] The position sensor 40 may acquire, as the position information, for example, the latitude and longitude of the de-orbiting device 3 when the debris collided with the debris sensor 39, as the latitude and longitude of the colliding debris. The method by which the position sensor 40 acquires the latitude and longitude is not particularly limited, and may be, for example, a method of calculating the altitude based on GPS signals received from multiple GPS satellites. Note that the position sensor 40 may acquire, as the position information, parameters for specifying the orbit of the debris that collided with the debris sensor 39. The parameters may include, for example, the semi-major axis of the orbit, the orbital eccentricity, the orbital inclination, the right ascension of the ascending node, the argument of periapsis, and the true anomaly, which are estimated based on the debris information described below, etc.

[0035] The communication device 37 is an example of a communication unit and is a communication module including an antenna, communication circuits, etc. for transmitting and receiving signals and data to and from any external device via a predetermined communication method. The communication device 37 may communicate with various devices, such as a ground control device, another spacecraft, or another deorbiting device installed on the spacecraft. Specifically, the communication device 37 may receive signals from these various devices and provide them to the control device 36. The communication device 37 may also transmit signals provided by the control device 36 to these various devices. The communication method (communication method) used by the communication device 37 is not particularly limited and may include, for example, any communication method using radio waves or light, such as a satellite telephone network or optical satellite communication. The frequency band used for communication may also be selectable. The communication device 37 may also communicate via a communication method using a satellite internet constellation such as Starlink. The communication device 37 may include, for example, multiple communication units using different communication methods. Here, different communication methods refer to, for example, different protocols (regardless of layer) or channels constituting the communication method. This allows communication to be maintained using other communication methods even if one communication method becomes unusable due to some kind of trouble.

[0036] The power supply unit 38 supplies power to, for example, the de-orbit device 3. The power supply unit 38 may have, for example, a battery capable of holding (storing) power to be supplied to the de-orbit device 3. The battery of the power supply unit 38 may be configured to be capable of holding power for supplying power to the de-orbit device 3. The battery of the power supply unit 38 may also be configured to be capable of holding power for supplying power to the spacecraft 2. The configuration of the battery of the power supply unit 38 is not particularly limited, and may be, for example, a lithium ion secondary battery, a fuel cell, or the like.

[0037] The power supply unit 38 may include, for example, a power generation unit that generates power to be supplied to the de-orbital device 3. The power generation unit of the power supply unit 38 may be configured to be able to supply the generated power to the de-orbital device 3. The configuration of the power generation unit of the power supply unit 38 is not particularly limited as long as it is capable of generating power. For example, the power generation unit may include a thin film for solar power generation, such as a silicon-based material such as crystalline silicon or amorphous silicon, a compound-based material such as CIS or CdTe, or an organic material such as dye-sensitized perovskite or paint. The power generation unit of the power supply unit 38 may be provided at any location on the de-orbital device 3 that can receive light such as sunlight, for example, on the outer surface of the outer shell that houses the de-orbital device. Alternatively, the power generation unit of the power supply unit 38 may be provided on at least a part of the tether 31. This allows the surface area of ​​the shape formed by the deployed tether 31 to be larger than that of the spacecraft 2, making it possible to effectively utilize the large surface area of ​​the tether 31 and improving the power generation efficiency of the power generation unit. In addition, if the tether 31 is made of a conductive material, the power generation unit may generate part of the power to be supplied to the orbital departure device 3 based on the current flowing through the tether 31 due to the induced electromotive force.

[0038] The control device 36 performs overall control of the orbital departure device 3. The control device 36 may be configured as a computer including a processor such as a CPU (Central Processing Unit) and memories such as a RAM (Random Access Memory) and a ROM (Read Only Memory).

[0039] (2) Control of the De-orbit Device 3 The control of the de-orbit device 3 by the control device 36 will be described with reference to Fig. 5. Fig. 5 is a functional block diagram showing an example of the functional configuration of the control device 36. The control device 36 includes a control unit 361 and a storage unit 362. The control unit 361 includes a tether control unit 361a, an environmental information processing unit 361b, and a transmission / reception unit 361c. These functional units are realized by a processor, a memory, etc. provided in the control device 36.

[0040] The tether control unit 361a controls the deployment and storage of the tether 31. For example, the tether control unit 361a opens an opening / closing lid (not shown) provided on the storage unit 33. This allows the tether 31 to be released to the outside of the storage unit 33. The tether control unit 361a then controls the opening degree of the electromagnetic valve 35 to supply gas from the gas supply unit 34 to the tether 31. As a result, the tether 31 is supplied with and filled with gas, and expands and deploys to form a predetermined shape, allowing it to be subjected to atmospheric resistance. Furthermore, because the tether 31 is filled with gas, for example, the occurrence of a phenomenon in which the end 31F of the tether 31 unwinds due to recoil upon completion of deployment is suppressed, making it easier for the tether 31 to maintain the predetermined shape it forms. This effect can be particularly noticeable when the tether 31 forms a flat shape. The speed at which the tether 31 is deployed by the supply of gas is not particularly limited, but may be, for example, a speed at which it takes several hours to deploy 1 meter, or a speed at which it takes several days to several months to deploy the tether 31. Due to the atmospheric resistance experienced by the tether 31, the spacecraft 2 equipped with the de-orbit device 3 gradually loses altitude and eventually leaves the circular orbit. The time from the start of de-orbit until the spacecraft 2 falls to an altitude at which it re-enters the atmosphere is not particularly limited, but may be several hours, several weeks, several months, several years, or several decades, etc.

[0041] The tether control unit 361a may control the speed at which the tether 31 is deployed, for example, via control of the gas supply unit 34 or the electromagnetic valve 35. The tether control unit 361a may control the speed at which the tether 31 is deployed based on the rate at which the detection line 39L is broken due to debris collisions in a debris sensor 39 provided on at least a portion of the tether 31. For example, the tether control unit 361a may deploy a predetermined length of the tether 31 when the rate reaches a predetermined threshold. The tether control unit 361a may also control the speed at which the tether 31 is deployed based on, for example, the altitude detected by the position sensor 40. In particular, the tether control unit 361a may maintain a constant ratio between the altitude descent rate of the de-orbital device 3 (spacecraft 2) and the deployment rate of the tether 31. Specifically, the tether control unit 361a may deploy the tether 31 by a predetermined length each time the spacecraft 2 (de-orbital device 3) descends by a predetermined altitude. This allows the part of the debris sensor 39 that has not yet been broken by a debris collision to remain deployed as the altitude of the spacecraft 2 descends, improving the accuracy of debris collision detection.

[0042] The environmental information processing unit 361b may, for example, store information about debris collisions detected by the debris sensor 39 (debris information) in the storage unit 362. The debris information may include, for example, the location of the debris collision, the dimensions of the colliding debris, the time of the debris collision, and the direction of the debris collision. The environmental information processing unit 361b may also store the debris information in the storage unit 362 in association with position information of the debris detected by the position sensor 40. The environmental information processing unit 361b may, for example, store the debris information in the storage unit 362 in association with the altitude, latitude, and longitude of the debris. The environmental information processing unit 361b may, for example, divide the altitude, latitude, and longitude of the debris into predetermined ranges and store the debris information for each range in the storage unit 362. Furthermore, the environmental information processing unit 361b may store the debris information in the storage unit 362 in association with a parameter for identifying the orbit of the debris.

[0043] The transmitter / receiver 361c controls the communication device 37 to transmit and receive signals and data to and from any external device. In particular, the transmitter / receiver 361c may control the communication device 37 to transmit and receive signals and data to and from various devices, such as a ground control device, another spacecraft, or another deorbiting device provided on the spacecraft.

[0044] The de-orbiting device according to this embodiment not only has the original function of de-orbiting an object such as a spacecraft from an orbit, but also has the function of detecting environmental information such as information on debris collisions. This makes it possible to obtain environmental information without manufacturing a device specifically for obtaining environmental information or launching it into space. Furthermore, the de-orbiting device not only de-orbits an object from an orbit, but also has the new added value of detecting environmental information, which can promote further utilization of the de-orbiting device.

[0045] (3) Modified Examples of the Tether 31 With reference to Figures 6A to 6D, 7A, and 7B, we will explain modified examples of the tether 31 provided in the orbital departure device 3. Figures 6A to 6D are schematic diagrams showing examples of cross-sectional views in a direction perpendicular to the longitudinal direction of various modified examples of the tether 31 provided in the orbital departure device 3.

[0046] 6A, the orbital departure device 3 may include a tether 31a having an elliptical cross-sectional shape. The ellipticity (the ratio of the minor axis to the major axis) of the elliptical cross-sectional shape of the tether 31a is not particularly limited.

[0047] As shown in Figure 6B, the orbital departure device 3 may include a tether 31b having a regular octagonal cross-sectional shape. Note that the cross-sectional shape of the tether 31b may be a triangle, a rectangle, a pentagon, a hexagon, or any other polygonal shape. Furthermore, the polygon is not limited to a regular polygon, and may also be an irregular polygon.

[0048] 6C, the orbital departure device 3 may include a tether 31c having a cross-sectional shape of a five-pointed star. Note that the cross-sectional shape of the tether 31c is not limited to the so-called five-pointed star shown in the figure, but may be other star-shaped polygons such as a six-pointed star or pointed star shape.

[0049] As shown in FIG. 6D , the orbital de-orbit device 3 may have four tethers 31d with a substantially circular cross-sectional shape. The number of tethers 31d included in the orbital de-orbit device 3 is not limited to four, and may be two, three, five, or more. The radii of the cross-sectional shapes of the tethers 31d may be the same or different. The arrangement of the tethers 31d is not particularly limited. For example, as shown in FIG. 6D , the centers of the tethers 31d may be arranged near the vertices of a diamond. At least two tethers 31 among the multiple tethers 31d may be connected to each other. Furthermore, at least one of the multiple tethers 31d may be tethers 31a, 31b, or 31c having another cross-sectional shape shown in FIGS. 6A to 6C , or may be a tether 31 having any other cross-sectional shape. By including multiple tethers 31 in the orbital de-orbit device 3, even if a hole is formed in one of the tethers 31 and gas leaks from that hole, the other tethers 31 can ensure the function of the orbital de-orbit device 3.

[0050] FIG. 7A is a schematic diagram showing an example of a portion of a tether 31e of a modified example viewed from a direction perpendicular to the longitudinal direction. FIG. 7B is a schematic diagram showing an example of a cross-sectional shape of a portion of a tether 31e of a modified example taken in a direction parallel to the longitudinal direction. The tether 31e may have multiple compartments (cells) 31f separated by partitions 31s. The dimensions of the compartments 31f may be the same or different between different compartments. The partitions 31s may be formed by adhering multiple thin film members of the tether 31e that overlap in a direction perpendicular to the longitudinal direction, or may be formed of a material different from the thin film members of the tether 31e. This makes it easier to maintain the structure of the tether 31 even when the longitudinal dimension of the tether 31 is increased. The multiple compartments 31f may be connected to each other via, for example, a gas supply channel (not shown). The gas supply channel may be provided with a valve that allows gas to flow in one direction. Furthermore, due to the configuration of the tether 31e, even if a hole is formed in one of the compartments 31f and gas leaks from that hole, gas will not leak from the other compartments 31f, making it easier to maintain the tether 31e in a deployed state.

[0051] (4) Object to which the De-orbit Device 3 is Attached The object to which the de-orbit device 3 is attached will be described with reference to Fig. 8. In the example described above, the de-orbit device 3 is described as being attached to the spacecraft 2. However, the object to which the de-orbit device 3 is attached is not limited to the spacecraft 2.

[0052] FIG. 8 shows a schematic diagram of a rocket 100 as an example of a structure including an object to which the orbital departure device 3 is attached. The rocket 100 has, for example, a first engine section 101, a second engine section 102, and a cover section 103. The rocket 100 operates, for example, as follows: First, the first engine section 101 ignites, launching the rocket 100 from the ground. When the rocket 100 reaches a certain altitude, the first engine section 101 detaches from the rocket 100, and the second engine section 102 ignites. When the rocket 100 reaches a predetermined altitude, the second engine section 102 detaches from the rocket 100. Then, the satellite separation section 105 in the cover section 103 activates, causing the satellite 104 to separate from the cover section 103. After being separated from the cover section 103, the satellite 104 begins to orbit using a predetermined propulsion device and performs a predetermined mission in the orbit.

[0053] As shown in Fig. 8, the rocket 100 is equipped with de-orbit devices 3a, 3b, and 3c. As shown in Fig. 8, the de-orbit device 3a may be equipped to a satellite 104 as a target object. The de-orbit device 3a may start deploying the tether 31 at a timing such as after the satellite 104 has completed its mission, thereby causing the satellite 104 to descend and de-orbit from the orbit. In this way, the de-orbit device 3a may be equipped to a target object, such as the satellite 104, that is capable of propelling itself in orbit and that performs a predetermined mission, and may de-orbit the target object from the orbit at a predetermined timing.

[0054] As shown in FIG. 8 , the de-orbit device 3b may be attached to the satellite separation unit 105 as the target. The de-orbit device 3b may start deploying the tether 31 at a timing such as after the separation of the satellite 104 is completed, thereby descending the satellite separation unit 105 and causing it to depart from the orbit. Also, as shown in FIG. 8 , the de-orbit device 3c may be attached to the main body of the cover unit 103 as the target. The de-orbit device 3c may start deploying the tether 31 at a timing such as after the separation of the satellite 104 is completed, thereby causing the main body of the cover unit 103 to descend and depart from the orbit. In this way, the de-orbit devices 3b and 3c may be attached to targets that do not have a function of propelling themselves in the orbit or targets that do not have a predetermined mission, and may cause the targets to depart from the orbit at a predetermined timing. In this way, by attaching a de-orbiting device 3 to an object that does not have a particular mission, it becomes possible to deploy many de-orbiting devices 3 in space, and the detection units provided in many of the de-orbiting devices 3 make it possible to efficiently collect environmental information.

[0055] (5) Mapping System 200 FIG. 9 is a schematic diagram showing an example of the configuration of a mapping system 200 according to another embodiment. The mapping system 200 is configured to be able to communicate with the de-orbiting devices 3 mounted on each of a plurality of spacecraft 2. The mapping system 200 is an example of an information processing system for collecting environmental information from each de-orbiting device 3 and generating a map of environmental information about positions in space (e.g., altitude, latitude, and longitude) based on the collected environmental information. The mapping system 200 may be configured to include one or more computers installed at any location on the ground. The computer may include, for example, a processor such as a CPU and memories such as RAM and ROM. The computer may also include a communication device for communicating with the de-orbiting devices 3 and other information processing devices. The computer may also include output devices such as a speaker and a display, and input devices such as a mouse and a keyboard.

[0056] 9 , the mapping system 200 includes, as examples of functional units, a storage unit 201 and a control unit 202. The control unit 202 includes an acquisition unit 202 a, a generation unit 202 b, an output unit 202 c, and an orbital departure device control unit 202 d. These functional units may be realized by a processor, a memory, etc. of a computer included in the mapping system 200.

[0057] The storage unit 201 is an example of a second storage unit and stores various data and programs. In particular, the storage unit 201 may store an environmental information map (described later) generated by the generation unit 203 or the like.

[0058] The acquisition unit 202a acquires environmental information detected by the de-orbit devices 3 from each of the multiple de-orbit devices 3. The acquisition unit 202a may, for example, acquire from the de-orbit devices 3, information on debris collisions (debris information) detected by the debris sensors 39 included in the de-orbit devices 3. The debris information may include, for example, the location of the debris collision, the dimensions of the colliding debris, the time of the debris collision, the direction of the debris collision, etc. Furthermore, the debris information may be associated with, for example, altitude, latitude, longitude, and parameters for identifying the orbit.

[0059] The generation unit 202b generates an environmental information map based on the environmental information acquired by the acquisition unit 202a from each of the multiple de-orbiting devices 3. The environmental information map may be, for example, information indicating the distribution of environmental information with respect to positions in space. The environmental information map may be, for example, information regarding debris (debris density, debris movement speed, debris dimensions, etc.) associated with altitude, latitude, and longitude in space, as well as parameters for identifying an orbit. The environmental information map may also be information indicating the distribution of other environmental information with respect to positions in space detected by a detection unit included in the de-orbiting device 3. The other environmental information may include, for example, atmospheric density, the Earth's magnetic field, plasma, the type and distribution of gravity and cosmic radiation, changes in radio wave intensity (how much radio waves are being transmitted from the satellite), the status of solar flares, images of the surrounding area, elementary particles, etc. The environmental information may also include information regarding electromagnetic waves emitted by other artificial satellites (information regarding compliance with electromagnetic wave laws and regulations, intensity, direction, frequency (band), bandwidth, communication timing, and information regarding the source and destination of the electromagnetic waves).

[0060] The method for generating the environmental information map by the generation unit 202b is not particularly limited, but for example, the environmental information map may be generated by statistically processing the environmental information acquired by the acquisition unit 202a, or the environmental information map may be generated based on the environmental information acquired by the acquisition unit 202a using a trained model that has undergone machine learning. The generation unit 203b may store the generated environmental information map in the storage unit 201.

[0061] The output unit 202c outputs the environmental information map generated by the generation unit 202b. The output unit 202c may, for example, output the environmental information map to an output device included in the mapping system 200. The output unit 205 may also transmit the environmental information map to the de-orbiting device 3 or another information processing device. The output unit 205 may also transmit the environmental information map to a debris collection device.

[0062] The mapping system 200 generates an environmental information map based on environmental information acquired from multiple de-orbiting devices 3. This facilitates the creation of a comprehensive environmental information map, which is difficult to achieve with only a single de-orbiting device 3, and the creation of a more efficient environmental information map.

[0063] The de-orbit device control unit 202d controls the de-orbit device 3 by generating and transmitting a control signal for controlling the de-orbit device 3 to the de-orbit device 3. The de-orbit device control unit 202d may, for example, control the timing at which the de-orbit device 3 is activated to start deploying the tether 31, or may control the speed at which the de-orbit device 3 deploys the tether 31. The de-orbit device control unit 202d may also control the de-orbit device 3 based on information included in the environmental information map. For example, if the amount of environmental information (such as information about debris) associated with a specific position in space (such as altitude, latitude, longitude, and parameters for specifying an orbit) in the environmental information map is relatively small, the de-orbit device control unit 202d may control an arbitrary de-orbit device 3 to move to the specific position (such as altitude, latitude, longitude, and parameters for specifying an orbit). This allows multiple de-orbit devices 3 to operate in coordination with each other under the management of the mapping system 200.

[0064] (6) Others A slave unit may be provided at the end 31F of the tether 31. The slave unit may be configured, for example, as a sensor for detecting a predetermined parameter. The slave unit may also be configured, for example, as a communication module for transmitting and receiving communication signals to and from any external device, and include an antenna and a communication circuit. The slave unit may also include a processor such as a CPU and memories such as RAM and ROM. The slave unit may, for example, acquire position information of the spacecraft 2 and the slave unit itself, or acquire the deployment status of the tether 31, and transmit and receive this information to and from the control unit 36, a ground management device, or another spacecraft.

[0065] The resistance generating unit of the deorbital device 3 is a tether 31 that receives atmospheric resistance as a resistance force against the movement of the spacecraft 2 in the orbit, or a tether 31 that includes a conductive material that generates Lorentz force as the resistance force. However, the resistance generating unit is not limited to the tether 31, and may be a thruster such as a cold gas thruster. In this case, the reaction force generated by the thruster ejecting gas in the direction of movement of the spacecraft 2 becomes the resistance force against the movement of the spacecraft 2 in the orbit. The thruster may also serve as a device that generates thrust for the spacecraft 2 to move in the orbit and a device that controls the attitude of the spacecraft 2. The configuration of the resistance generating unit that receives atmospheric resistance is not limited to an inflatable structure or a tether-shaped one, and may be, for example, cloth-shaped, fan-shaped, umbrella-shaped, bag-shaped, or the like, or may be composed of a frame and a sheet.

[0066] In the above-described embodiment, the de-orbit device 3 includes a debris sensor 39 for detecting debris collisions as an example of a detector. However, the de-orbit device 3 may also include a detector for detecting the environment in space other than debris. The environment detected by the detector may include, for example, atmospheric density, the Earth's magnetic field, plasma, the type and distribution of gravity and cosmic radiation, changes in radio wave intensity (how much radio waves are being emitted from the satellite), the status of solar flares, images of the surrounding area, elementary particles, etc. Furthermore, the environment detected by the detector may also include information about electromagnetic waves emitted by other artificial satellites (whether or not they comply with laws and regulations regarding electromagnetic waves, their intensity, direction, frequency (band), bandwidth, communication timing, and information about the source and destination of the electromagnetic waves).

[0067] The de-orbit device 3 may calculate information indicating the trajectory and speed of the de-orbit device 3 as it descends from orbit, for example, based on position information acquired by the position sensor 40 or the like. The de-orbit device 3 may then calculate the resistance force (atmospheric resistance, etc.) that the de-orbit device 3 will experience as it descends from orbit based on the information, and then calculate the atmospheric density based on the resistance force. The process of calculating the atmospheric density may also be performed by an external device (e.g., the mapping system 200) that acquires the position information acquired by the position sensor 40 or the like from the de-orbit device 3. In particular, the mapping system 200 can acquire information indicating the trajectory and speed of the de-orbit device 3 as it descends from orbit, from multiple de-orbit devices 3. Therefore, by comparing and analyzing the information acquired from multiple de-orbit devices 3, for example, over a long period of time, it is possible to generate a highly accurate map of atmospheric density over a wide range.

[0068] In the above-described embodiment, the debris sensor 39 is configured to include a detection line 39L provided on a thin insulating film. However, the debris sensor 39 is not limited to this configuration, and may, for example, use a minute sensor such as a piezoelectric element or diaphragm provided in an arbitrary region of the tether 31 to measure vibrations that occur when debris collides with the tether 31, thereby detecting a debris collision.

[0069] In the above-described embodiment, the de-orbit device 3 is equipped with the position sensor 40, and debris collision information from the debris sensor 39 is stored in the storage unit 362 in association with the position information detected by the position sensor 40. However, the de-orbit device 3 may detect the time of debris collision instead of the position information, and store the debris collision information in association with the time in the storage unit 362. Specifically, for example, the debris sensor 39 may acquire the time when the debris collision was detected under the control of the control unit 361 (environmental information processing unit 361b, etc.), and supply the detection result including the time to the control unit 361. Then, the control unit 361 (environmental information processing unit 361b) may associate the time with the debris collision information and store it in the storage unit 362. Thereafter, the de-orbiting device 3, or an external device (e.g., the mapping system 200) that acquires the debris collision information associated with the time from the de-orbiting device 3, may generate position information at the time of the debris collision by combining the acquired time with information such as the descent trajectory of the spacecraft 2.

[0070] The above-described embodiments are intended to facilitate understanding of the present invention and are not intended to limit the present invention. The elements of the embodiments, as well as their arrangement, materials, conditions, shapes, sizes, etc., are not limited to those illustrated and can be modified as appropriate. Furthermore, configurations shown in different embodiments can be partially substituted or combined with each other.

[0071] 2...spacecraft, 3...deorbital device, 31, 31a, 31b, 31c, 31d, 31e...tether, 31f...compartment, 31s...partition, 31F, 31T...end, 33...accommodation section, 34...gas supply section, 35...electromagnetic valve, 36...control device, 37...communication device, 38...power supply section (battery section or power generation section), 39...debris sensor, 39L, 39La, 39Lb...detection line, 40...position sensor 361...control unit, 361a...tether control unit, 361b...environmental information processing unit, 361c...transmitter / receiver unit, 362...storage unit, 100...rocket, 101...first engine, 102...second engine unit, 103...cover unit, 200...mapping system, 201...storage unit, 202...control unit, 202a...acquisition unit, 202b...generation unit, 202c...output unit, 202d...orbital departure device control unit

Claims

1. An orbital detachment device mounted on an object moving in an orbital path in space, comprising: a resistance generating unit that generates a resistance force against the movement of the object on the orbital path; a detection unit that detects environmental information indicating a predetermined environment during the generation of the resistance force by the resistance generating unit; a storage unit; and an environmental information processing unit that stores the environmental information in the storage unit.

2. The orbital detachment device according to claim 1, wherein the detection unit is provided in at least a part of the resistance generating unit.

3. The orbital detachment device according to claim 1, further comprising a position acquisition unit that acquires position information indicating a position associated with the predetermined environment during the generation of the resistance force by the resistance generating unit, wherein the environmental information processing unit stores the environmental information and the position information in association with each other in the storage unit.

4. The orbital detachment device according to claim 3, wherein the position acquisition unit acquires, as the position information, the altitude of the orbital detachment device when the detection unit detects the environmental information.

5. The orbital detachment device according to claim 4, wherein the position acquisition unit further acquires, as the position information, the latitude and longitude of the orbital detachment device when the detection unit detects the environmental information.

6. The orbital detachment device according to claim 1, wherein the detection unit acquires the time when the environmental information is detected and detects the environmental information including the time.

7. The orbital detachment device according to claim 1, wherein the resistance generating unit is configured to be deployable to form a predetermined shape for receiving atmospheric resistance as the resistance force.

8. The orbital detachment device according to claim 7, wherein the resistance generating unit expands by supplying gas therein to form the predetermined shape.

9. The orbital detachment device according to claim 7 or 8, wherein the detection unit includes a conducting wire provided in at least a part of the resistance generating unit, and detects information regarding a collision of the space floating object as the environmental information based on a breakage of the conducting wire due to a collision of the space floating object.

10. The orbital detachment device according to claim 9, wherein the detection unit detects the direction of the collision of the space floating object based on the position of the first collision of the space floating object and the position of the second collision of the space floating object.

11. The orbital detachment device according to claim 10, wherein the detection unit further detects the speed of the collision of the space floating object based on the time of the first collision and the time of the second collision.

12. The orbital detachment device according to claim 1, further comprising a power supply unit for supplying power to the orbital detachment device.

13. The orbital detachment device according to claim 12, wherein the power supply unit includes a battery unit for holding power to be supplied to the orbital detachment device and / or a power generation unit for generating power to be supplied to the orbital detachment device.

14. The orbital detachment device according to claim 1, further comprising a communication unit for performing communication regarding the environmental information.

15. The orbital detachment device according to claim 14, further comprising a second communication unit for performing communication regarding the environmental information by a communication method different from that of the communication unit.

16. The communication unit of the orbital detachment device according to claim 14 performs communication regarding the environmental information with an information processing device on the ground, another object moving in an orbit in space, or another orbital detachment device provided in the other object.

17. An information processing system comprising: a second storage unit; an acquisition unit that acquires the environmental information from each of the plurality of orbital detachment devices according to claim 1 and stores the environmental information in the second storage unit; and a generation unit that generates a distribution of the environmental information in space based on the environmental information stored in the second storage unit.

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