Artificial satellite

Abstract

[Problem] To stabilize the shape of a wooden casing of an artificial satellite to withstand use in outer space. [Solution] According to the present invention, a wooden casing is constructed by assembling six wooden panels 201 to 206 in a cuboid shape, mutually adjacent wooden panels among two wooden panels 201, 202 that face each other in the X-axis direction and two wooden panels 203, 204 that face each other in the Y-axis direction, among the six wooden panels, being joined together using hidden dovetail joints, wherein the two wooden panels 203, 204 that face each other in the Y-axis direction are connected to four Y-direction couplers 34 in order to suppress loosening of the structure of the wooden casing associated with contraction of the wooden panels 201 to 206.

Description

artificial satellite

[0001] The present invention relates to a technique for stabilizing the shape of a wooden casing of an artificial satellite.

[0002] The number of artificial satellite launches has been increasing in recent years. According to the Cabinet Office's Space Development Strategy Headquarters' "Awareness of the Environment Surrounding Space Transportation and Its Future Vision" (https: / / www8.cao.go.jp / space / comittee / 05-yuso / yuso-dai2 / siryou2.pdf), the number of launches in 2013 was 206, while the number of launches in 2022 is expected to be 2,368, an increase of approximately 11 times in about 10 years. In particular, the number of commercial satellite launches is expected to increase further in the future.

[0003] In recent years, various industrial fields have been making efforts to solve ecological issues. For example, efforts are being made to improve the materials used in products so as to minimize the burden on the global environment. In the space industry, the use of wood in artificial satellites has been proposed (Non-Patent Document 1).

[0004] Trees are a renewable resource that can be grown. In the future, by growing trees on space stations and other facilities, it will be possible to obtain wood for building satellites and homes, thereby resolving resource procurement issues. It will also help reduce transportation costs from Earth to space.

[0005] Wood has the property of transmitting electromagnetic waves and geomagnetic fields, so antennas and attitude control devices that were previously attached to the outside of satellites can now be installed inside, which allows the size of the satellite itself to be reduced.

[0006] Wood is also easy to process. Metal processing requires the use of special machine tools, which emits carbon dioxide during the process. However, wood processing only requires saws and planes. Therefore, using wood as a material can reduce carbon dioxide emissions during the manufacturing process.

[0007] Furthermore, metals burn when they enter the atmosphere, releasing air pollutants such as alumina particles. However, wood burns up when it enters the atmosphere. Therefore, even if a satellite made of wood is re-entered into the atmosphere after its operational life is over, the burden on the Earth's atmosphere is small.

[0008] In this way, using wood as a material for things used in space, such as artificial satellites, is an effective means of solving ecological issues.

[0009] "Kyoto University / Sumitomo Forestry: Examining the Possibility of Using Wood in Space" (Sohjusha Monthly Magazine "Housing Tribune" Vol. 651 https: / / htonline.sohjusha.co.jp / 651-052 / )

[0010] However, there are several challenges to operating a wooden satellite in space. One of these is that the wooden structure expands and contracts with temperature changes, which can easily cause the satellite's casing to warp.

[0011] In view of the above problems, the present invention aims to stabilize the shape of the wooden casing of an artificial satellite so that it can withstand use in outer space.

[0012] A satellite according to one embodiment of the present invention comprises a wooden casing constructed by assembling six wooden boards into a rectangular parallelepiped shape, in which two of the six wooden boards facing each other in the X-axis direction and adjacent two of the six wooden boards facing each other in the Y-axis direction are joined together using hidden dovetail joints, and four couplers that connect four pairs of opposing corners of the two wooden boards facing each other in the Y-axis direction to suppress loosening of the wooden casing structure due to shrinkage of the six wooden boards.

[0013] Preferably, the wooden housing has a protector that covers the edges and has first holes at each of the four corners of the +Y side surface and the four corners of the -Y side surface, and each of the two wooden boards facing each other in the Y axis direction has a second hole at each of the four corners, and each of the four connectors has a screw hole at the +Y side end face and the -Y side end face, and the four connectors connect the two wooden boards facing each other in the Y axis direction by inserting a screw whose head diameter is larger than the diameter of the first hole through the first hole, passing it through the second hole, and tightening it into the screw hole.

[0014] According to the present invention, the shape of the wooden casing of the satellite can be stabilized so that it can withstand use in outer space.

[0015] 1 is a diagram showing an example of the appearance of an artificial satellite. 2 is a diagram showing examples of components built into a wooden casing. 3 is a diagram showing an example of the arrangement of a second antenna. 4 is a diagram showing an example of the appearance of a wooden casing. 5 is a diagram showing an example of the configuration of a second antenna. 6 is a diagram showing an example of the configuration of an X-direction coupler. 7 is a diagram showing an example of a procedure for assembling a computer system. 8 is a diagram showing an example of a procedure for assembling a computer system. 9 is a diagram showing an example of a procedure for assembling a computer system. 10 is a diagram showing an example of a Y-direction coupler. 11 is a diagram showing an example of a procedure for attaching a Y-direction coupler to a computer system. 12 is a diagram showing an example of attaching a first connection part and a second connector. 13 is a perspective view showing an example of a wooden board on the +X side. 14 is a six-view diagram showing an example of a wooden board on the +X side. 15 is a perspective view showing an example of a wooden board on the -X side. 16 is a six-view diagram showing an example of a wooden board on the -X side. 17 is a perspective view showing an example of a wooden board on the +Y side. 18 is a six-view diagram showing an example of a wooden board on the +Y side. 19 is a perspective view showing an example of a wooden board on the -Y side. 20 is a six-view diagram showing an example of a wooden board on the -Y side. 21 is a diagram showing an example of a wooden board on the +Z side. 22 is a diagram showing an example of a wooden board on the -Z side. 23 is a diagram showing an example of a wooden board on the -Z side. 24 is a diagram showing an example of a procedure for assembling a wooden casing. 25 is a diagram showing an example of a rectangular hidden dovetail joint. 1 is a diagram showing an example of a protector; FIG. 2 is a diagram showing an example of a frame; FIG. 3 is a diagram showing an example of a frame; FIG. 4 is a diagram showing an example of a leg; FIG. 5 is a diagram showing an example of a leg; FIG. 6 is a diagram showing an example of a fixing member; FIG. 7 is a diagram showing an example of a corner of a frame; FIG. 8 is a diagram showing an example of a procedure for assembling a protector; FIG. 9 is a diagram showing an example of a procedure for assembling a protector; FIG. 10 is a diagram showing an example of the positional relationship between a Y-direction coupler, an X-direction coupler, and a protector; FIG. 11 is a diagram showing an example of a method for connecting a wooden board and a Y-direction coupler; A perspective view showing an example of a 2U class artificial satellite; A six-sided view showing an example of a 2U class artificial satellite; A diagram showing an example of a wooden board used on the +Z side or -Z side.

[0016] 1. Overall configuration of the satellite 1 and overview of each part Fig. 1 is a diagram showing an example of the external appearance of the satellite 1. Fig. 2 is a diagram showing an example of components built into the wooden casing 2. Fig. 3 is a diagram showing an example of the arrangement of the second antenna 32. Fig. 4 is a diagram showing an example of the external appearance of the wooden casing 2. Fig. 5 is a diagram showing an example of the configuration of the second antenna 32.

[0017] The satellite 1 shown in FIGS. 1A and 1B is a 1U class microsatellite conforming to the CubeSat standard, and one of its features is that wood is used as part of its material.

[0018] The artificial satellite 1 is composed of a wooden casing 2, a first antenna 31, five solar panels 33, a protector 36, etc. The wooden casing 2 also houses a computer system 30, four Y-direction couplers 34, and four X-direction couplers 35, as shown in Figure 2. Furthermore, a second antenna 32 is attached to one of the inner surfaces of the wooden casing 2. For example, as shown in Figure 3, it is attached to the inner surface on the +X side.

[0019] The wooden housing 2 has six wooden boards 20, which are assembled into a rectangular parallelepiped shape as shown in Fig. 4. Hereinafter, the wooden boards 20 arranged on the +X side, -X side, +Y side, -Y side, +Z side, and -Z side may be referred to as "wooden board 201," "wooden board 202," "wooden board 203," "wooden board 204," "wooden board 205," and "wooden board 206," respectively.

[0020] The wooden board 20 is made by cutting and processing diffuse-porous wood such as magnolia, wild cherry, or Erman's birch into a board with a surface area of ​​approximately 100 mm × 100 mm or approximately 100 mm × 115 mm and a thickness of approximately 5.5 mm. In this embodiment, an artificial satellite having a size of 100 mm × 100 mm × 114 mm will be described as an example of the artificial satellite 1.

[0021] These diffuse-porous woods have small vessels scattered relatively uniformly, and are less susceptible to the high vacuum in low Earth orbit, galactic cosmic rays, solar energy particles, ultraviolet rays, and atomic oxygen than ring-porous and radiation-porous woods. Therefore, they are suitable as materials for artificial satellites and other equipment exposed to outer space. While diffuse-porous wood is preferred for the wooden board 20, ring-porous or radiation-porous wood, or even softwood, may also be used.

[0022] 2, the computer system 30 is configured with a backplane 301 and multiple expansion cards 302 (3021, 3022, ...), and performs processes such as calculations, communications, measuring various environments, and power supply control. For example, one of the expansion cards 302 is equipped with a geomagnetic sensor that measures geomagnetism.

[0023] The backplane 301 is an electronic board (electronic circuit) with multiple slots aligned along the X axis, and interconnects the expansion cards 302 inserted into each slot. In other words, it functions as the backbone of the computer system 30. In addition, a primary battery or a secondary battery is also provided.

[0024] The expansion card 302 is a PCB (Printed Circuit Board) equipped with electronic circuits or electronic components for realizing specific functions. For example, a main board, a communication board, a power supply control board, etc. are used as the expansion card 302. Note that the backplane 301 may be provided with a main CPU (Central Processing Unit), main memory, etc., and configured as a motherboard.

[0025] The first antenna 31 is an antenna for wireless communication with a ground station in the UHF (Ultra High Frequency) band or the VHF (Very High Frequency) band, and is provided on the outer surface of the wooden casing 2 as shown in FIG. 1(A).

[0026] The two flexible antenna elements 31a and 31b of the first antenna 31 are stored in a circular folded state and tied with fishing line until the satellite 1 is launched into space, but after launch, the fishing line is burned off and the antenna elements unfold due to their own elasticity and become stretched out in a straight line. As the first antenna 31, for example, a 435 MHz (UHF) dipole antenna is used.

[0027] The second antenna 32 is an antenna for wireless communication with a ground station in the 2.4 GHz or 5 GHz frequency band, and is attached to the inner surface of the wooden casing 2 as shown in FIG.

[0028] 3 shows an example in which the second antenna 32 is closely attached to the wooden housing 2, but it is preferable to place it at a distance of about 5 to 10 mm to reduce the influence of the characteristics of the wooden housing 2. Also, an expansion card 302 incorporating the second antenna 32 may be inserted into the outermost slot of the backplane 301.

[0029] Since a space is required to mount the second antenna 32, if it cannot be mounted on a 1U class satellite 1, it may be mounted on a 2U class satellite 12 (see Figures 36 and 37) described later. Alternatively, the second antenna 32 may be disposed on the outer surface of the wooden casing 2. Alternatively, the first antenna 31 may not be mounted, and the second antenna 32 may be attached to the surface where the first antenna 31 was attached.

[0030] The second antenna 32 is a patch antenna as shown in Figure 5, and consists of a rectangular dielectric substrate 321 made of a dielectric material such as resin or glass, a circular antenna copper plate 322 provided on its surface, and a rectangular ground copper plate 323 provided on its back surface.

[0031] To give an example of dimensions, when the operating frequency is 2.45 GHz and the power supply impedance is 50 Ω, the outer dimensions of the dielectric substrate 321 are 90 × 90 mm, the thickness is 1.57 mm, and the relative dielectric constant is 2.16, the diameter of the antenna copper plate 322 is 46.4 mm, and the thickness is 0.035 mm, the outer dimensions of the ground copper plate 323 are the same as the dielectric substrate 321, 90 × 90 mm, and the thickness is 0.035 mm, and the offset distance from the center point of the antenna copper plate 322 to the power supply point PA is 5.9 mm.

[0032] An SMA connector 324 is attached to the feeding point PA, and power is fed via a coaxial cable, etc. The second antenna 32 is attached so that the surface of the antenna copper plate 322 faces one of the wooden boards 20 of the wooden housing 2.

[0033] Such a second antenna 32 has directivity in an outward direction perpendicular to the surface of the antenna copper plate 322. Therefore, the direction of the directivity can be determined and the antenna can be disposed taking into consideration the purpose of use of the second antenna 32, the division of roles with the first antenna 31, ease of attitude control of the artificial satellite 1, and the like.

[0034] For example, it is arranged so that the surface of the antenna copper plate 322 faces the inner surface of one of the wooden boards 20 of the wooden casing 2, for example, the wooden board 202 on the -X side, with a small gap between them. By arranging it in this way, it has almost the same directivity as the first antenna 31, which is advantageous for communication with a ground station in the same direction.

[0035] Furthermore, because the directivity of the first antenna 31 does not change in a plane perpendicular to the length direction, the second antenna 32 may be positioned to face the +X side wooden board 201, the +Y side wooden board 203, or the -Y side wooden board 204. If the second antenna 32 is positioned to face the +X side wooden board 201 and has directivity toward the +X side, it is possible to provide a director on the outer surface of the +X side wooden board 201, for example, that does not significantly affect the characteristics of the second antenna 32, and to make the first antenna 31 a two-element Yagi-Uda antenna to improve the gain toward the +X side. Even in this case, the wooden housing 2 minimizes the impact on the antenna characteristics, allowing the first antenna 31 and the second antenna 32 to operate efficiently.

[0036] Furthermore, when directing the directivity toward a station other than a ground station, such as a space station, another artificial satellite, or a radio wave reflecting object in space, the second antenna 32 may be disposed in a location appropriate to the station. Depending on the location of the second antenna 32, the attitude of the artificial satellite 1 may be controlled so that the directivity of the second antenna 32 is directed toward the communication partner station.

[0037] The solar panel 33 is a power generation device that generates electricity using sunlight, and one is attached to each of the five outer surfaces of the six outer surfaces of the wooden casing 2, except for the surface on which the first antenna 31 is mounted.

[0038] The Y-direction coupler 34 is connected to two wooden boards 20 facing each other in the Y direction, i.e., wooden board 203 and wooden board 204. The X-direction coupler 35 is connected to the ends of two Y-direction couplers 34 facing each other in the X direction. The protector 36 is a three-dimensional frame that protects the wooden housing 2 by covering the twelve edges of the wooden housing 2.

[0039] Although metals, synthetic resins, etc. can be used as these materials (raw materials), aluminum alloys, stainless steel, etc. are preferably used in terms of strength, durability, processability, thermal expansion coefficient, etc. For example, stainless steel is preferably used as the material for the Y-direction coupler 34 and the X-direction coupler 35. An aluminum alloy, for example, a 6000 series aluminum alloy that has been heat treated, is preferably used as the material for the protector 36, and various anodizing treatments may be performed as necessary.

[0040] 2. Procedure for assembling the satellite 1 and details of each part Next, a procedure for assembling the satellite 1 will be described, along with details of each part.

[0041] 2.1 Assembly of the Computer System 30 Figure 6 is a diagram showing an example of the configuration of the X-direction coupler 35. Figures 7 to 9 are diagrams showing an example of the procedure for assembling the computer system 30.

[0042] Four X-direction couplers 35 (351 to 354) are used when assembling the computer system 30. As shown in FIG. 6A or 7A and 7B, these X-direction couplers 35 are composed of a cylindrical, elongated shaft 35e (35ea to 35ed), a first connector 35f (35fa to 35fd), and a second connector 35g (35ga to 35gd).

[0043] A male thread is provided on the outer peripheral surface of the shaft 35e over almost the entire length. In this embodiment, the first connector 35f is integrally formed with the shaft 35e at the end on the +X side of the shaft 35e. The first connector 35f has a small-diameter portion at its outer end, resulting in a two-step end face, and a screw hole (female thread) is provided at the end face of the small-diameter portion, i.e., the tip. The dimensions between the -X side end face of the shaft 35e, the inner end face of the first connector 35f, the end face extending from the bottom of the small-diameter portion to the outer peripheral surface, and the end face of the small-diameter portion are all precisely finished, ensuring a high-precision finish when assembled.

[0044] The second connector 35g is substantially cylindrical, with a threaded hole penetrating along its central axis, a small-diameter portion at one end forming a two-step end face, and a two-sided width on its outer periphery that serves as an engagement portion for screwing and rotation. After the shaft 35e of the second connector 35g is passed through the hole in the expansion card 302 and the metal spacer, it is screwed into the threaded hole at the -X side end of the shaft 35e and fixed in place by tightening with an appropriate torque.

[0045] As will be described later, the first connector 35f and the second connector 35g also function as spacers interposed between the Y-direction coupler 34 and the expansion card 302. In particular, the first connector 35f is formed integrally with the shaft 35e, ensuring dimensional accuracy of the internal structure.

[0046] As described above, the backplane 301 of the computer system 30 has a plurality of slots. In this embodiment, it has five slots 301a to 301e as shown in FIG.

[0047] Each expansion card 302 has a circular hole at each of its four corners. For example, the first expansion card 3021 has holes 302a to 302d. Similarly, the cover (described later) has holes of the same size at the same positions.

[0048] The shafts 35ea to 35ed can be inserted through the holes 302a to 302d. However, because the outer diameters of the first connectors 35fa to 35fd and the second connectors 35ga to 35gd are larger than the inner diameters of the holes 302a to 302d, their end faces abut against the surface of the expansion card 302, and they cannot be inserted through the holes 302a to 302d.

[0049] As shown in FIG. 7B, the worker inserts the expansion card 3021 into the first slot of the backplane 301, that is, the slot 301a.

[0050] The worker then places the cover 303 next to the expansion card 3021 as shown in FIG. 8A.

[0051] The cover 303 surrounds and protects the electronic components on the expansion card 3021. It is roughly box-shaped, with a flange extending from the bottom of the box, and holes 303a to 303d similar to those on the expansion card 302 are provided in this flange.

[0052] In this state, the shafts 35ea to 35ed are inserted through the holes 302a to 302d of the expansion card 3021, then through the pipe-shaped spacers 3041 to 3044, and finally through the holes 303a to 303d of the cover 303.

[0053] The worker then inserts and positions the second and subsequent expansion cards 3022, 3023, 2024, and 3025 into slots 301b to 301e of the backplane 301, as shown in Figures 8(B) and 9(A), and with spacers 3041 to 3044 placed between them, inserts shafts 35ea to 35ed into the respective holes in sequence.

[0054] Then, the male threads at the ends of the shafts 35ea to 35ed are screwed into the screw holes of the second connectors 35ga to 35gd, and the screws are tightened.

[0055] As a result, as shown in Figure 9 (B), all expansion cards 3021 to 3025 and cover 303 inserted into slots 301a to 301e are connected by shafts 35ea to 35ed, with spacers 3041 to 3044 of lengths that match the respective spacing between them sandwiched between them, and both ends of these are sandwiched and tightened by first connectors 35fa to 35fd and second connectors 35ga to 35gd.

[0056] As a result of the above, the computer system 30 is assembled on the backplane 301 and held by the X-direction connectors 35 .

[0057] In this state, the computer system 30 is held by four shafts 35ea to 35ed, and at each end of the four shafts 35ea to 35ed, a two-tiered end of the first connectors 35fa to 35fd and the second connectors 35ga to 35gd and a screw hole in the center of the end face are arranged, and these two-tiered ends and screw holes are used to accurately attach the computer system to the Y-direction coupler 34 and protector 36.

[0058] 2.2 Attaching the Y-Direction Coupler 34 Fig. 10 is a diagram showing an example of the Y-direction coupler 34. Fig. 11 is a diagram showing an example of a procedure for attaching the Y-direction coupler 34 to the computer system 30. Fig. 12 is a diagram showing an example of attaching the first connection portion 34fa and the second connector 35ga.

[0059] When the assembly of the computer system 30 is completed, the worker attaches the Y-direction connector 34 to the X-direction connector 35 .

[0060] 10A to 10D, the Y-direction couplers 34 (341 to 341) are formed integrally with shafts 34ea to 34ed, first connection portions 34fa to 34fd, and second connection portions 34ga to 34gd. The first connection portions 34fa to 34fd are formed at the +Y side ends of the shafts 34ea to 34ed, respectively, and the second connection portions 34ga to 34gd are formed at the -Y side ends of the shafts 34ea to 34ed.

[0061] The first connecting portions 34fa to 34fd are provided with threaded holes 34ia to 34id, holes 34ja to 34jd, and threaded holes 34ka to 34kd, respectively, formed in cylindrical bosses, while the second connecting portions 34ga to 34gd are provided with threaded holes 34ra to 34rd, holes 34sa to 34sd, and threaded holes 34ta to 34td, respectively.

[0062] The holes 34ja, 34jb, 34sa, and 34sb are two-stage holes consisting of a large diameter hole and a small diameter hole, with the large diameter hole located on the +X side.

[0063] As shown in Fig. 11(A), the worker attaches the Y-direction coupler 341 to the X-direction couplers 351 and 353. Specifically, first, the worker inserts the second connector 35ga (see Figs. 6(A) and 6(B)) of the X-direction coupler 351 into the hole 34ja of the first connection portion 34fa of the Y-direction coupler 341, and similarly inserts the second connector 35gc of the X-direction coupler 353 into the hole 34sa of the second connection portion 34ga. These are fitted together with precision.

[0064] Similarly, the second connector 35gb of the X-direction coupler 352 and the second connector 35gd of the X-direction coupler 354 are inserted into the hole 34jb of the first connection portion 34fb of the Y-direction coupler 342 and the hole 34sb of the second connection portion 34gb, respectively.

[0065] Then, as partly shown in FIG. 12, four screws 34va, 34vb, 34vc, and 34vd are screwed into four screw holes provided on the end faces of the second connectors 35ga, 35gb, 35gc, and 35gd, respectively, and tightened.

[0066] As a result, the Y-direction connector 341 is fixed to one end of each of the X-direction connectors 351 and 353 , and the Y-direction connector 342 is fixed to one end of each of the X-direction connectors 352 and 354 .

[0067] Similarly, as shown in FIG. 11(B), using four screws 34ve, 34vf, 34vg, and 34vh, the Y-direction coupler 343 is attached to the other end of each of the X-direction couplers 352 and 354, and the Y-direction coupler 344 is attached to the other end of each of the X-direction couplers 351 and 353 (see FIGS. 6(A) and 7(A)).

[0068] As a result, the Y-direction connector 343 is fixed to the other end of each of the X-direction connectors 352 and 354 , and the Y-direction connector 344 is fixed to the other end of each of the X-direction connectors 351 and 353 .

[0069] This completes the attachment of the four Y-direction couplers 34 to the four X-direction couplers 35 .

[0070] 2.3 Assembly of the Wooden Casing 2 FIG. 13 is a perspective view showing an example of a wooden board 201 on the +X side. FIG. 14 is a six-view diagram showing an example of a wooden board 201 on the +X side. FIG. 15 is a perspective view showing an example of a wooden board 202 on the -X side. FIG. 16 is a six-view diagram showing an example of a wooden board 202 on the -X side. FIG. 17 is a perspective view showing an example of a wooden board 203 on the +Y side. FIG. 18 is a six-view diagram showing an example of a wooden board 203 on the +Y side. FIG. 19 is a perspective view showing an example of a wooden board 204 on the -Y side. FIG. 20 is a six-view diagram showing an example of a wooden board 204 on the -Y side. FIG. 21 is a diagram showing an example of a wooden board 205 on the +Z side. FIG. 22 is a diagram showing an example of a wooden board 206 on the -Z side. FIG. 23 is a diagram showing an example of a procedure for assembling the wooden casing 2. FIG. 24 is a diagram showing an example of a rectangular hidden dovetail joint.

[0071] After the Y-direction coupler 34 has been attached, the worker assembles the wooden casing 2, incorporating the computer system 30 and other components. As shown in FIG.

[0072] The wooden board 201 is the +X side wooden board 20, and as shown in Figures 13 and 14, it has two grooves 201a and 201b, two female portions 201c and 201d, and four holes 201e, 201f, 201g, and 201h. Furthermore, two of the four corners on the -Z side have slight missing portions, as can be seen by comparing them with the two corners on the +Z side. Hereinafter, these two missing portions will be referred to as "missing portion 201i" and "missing portion 201j," respectively. Furthermore, the fore-end surface appears on the +Y side and the -Y side.

[0073] The wooden board 202 is the -X side of the wooden board 20, and as shown in Figure 15 or 16, it has two grooves 202a and 202b, two female parts 202c and 202d, and four holes 202e, 202f, 202g, and 202h. It also has notches 202i and 202j at the two corners on the -Z side. Similar to the wooden board 201, the end faces appear on the +Y and -Y sides.

[0074] The wooden board 203 is the +Y side wooden board 20, and as shown in Figure 17 or 18, it has two grooves 203a and 203b, two male parts 203c and 203d, and four holes 203e, 203f, 203g, and 203h. It also has notches 203i and 203j at the two corners on the -Z side. The end faces are also visible on the +X and -X sides.

[0075] The wooden board 204 is the -Y side of the wooden board 20, and as shown in Figure 19 or 20, it has two grooves 204a and 204b, two male parts 204c and 204d, and four holes 204e, 204f, 204g, and 204h. It also has notches 204i and 204j at the two corners on the -Z side. Similar to the wooden board 203, the end faces appear on the +X and -X sides.

[0076] The wooden board 205 is the wooden board 20 on the +Z side, and as shown in FIG. 21, has four protrusions (tongues) 205a to 205d.

[0077] The wooden board 206 is the wooden board 20 on the -Z side, and has four protrusions 206a to 206d as shown in Fig. 22. Furthermore, it has notches 206e and 206f at the two corners on the +X side, and notches 206g and 206h at the two corners on the -X side.

[0078] The worker attaches one solar panel 33 to each of the outer surfaces of the wooden boards 201, 205, and 206, attaches a first antenna 31 to the wooden board 202, and attaches, for example, a second antenna 32 to the inner surface of the wooden board 201. Furthermore, as shown in Figure 23(A), the worker brings the wooden boards 201, 202, 205, and 206 close to the computer system 30 in their respective predetermined orientations, and wires the first antenna 31, second antenna 32, and three solar panels 33 to the computer system 30.

[0079] However, it has been found that RTV (Room Temperature Vulcanization) silicone adhesive, which has been conventionally used as a space adhesive, does not bond PCBs to wooden boards at all. Therefore, the PCBs used in the solar panels 33 cannot be attached to the wooden boards 20 using RTV silicone adhesive.

[0080] Therefore, the worker applies a primer to both the wooden board 20 and the cells of the solar panel 33, and then bonds them together with an RTV silicone adhesive.

[0081] It is also desirable to install the second antenna 32 about 1 cm away from the wooden board 202. For example, the second antenna 32 may be attached to the wooden board 202 with spacers about 1 cm long, one at each of the four corners of the second antenna 32.

[0082] Furthermore, the worker brings the wooden board 205 into contact with predetermined positions of the Y-direction couplers 342 and 344, and brings the wooden board 206 into contact with predetermined positions of the Y-direction couplers 341 and 343. Then, in this state, the wooden board 201 and the wooden boards 205 and 206 are joined together so that the protrusions 205a and 206a of the wooden board 206 fit into the grooves 201a and 201b of the wooden board 201, respectively. Furthermore, the wooden board 202 and the wooden boards 205 and 206 are joined together so that the protrusions 205b and 206b of the wooden board 206 fit into the grooves 202a and 202b of the wooden board 202, respectively.

[0083] As a result, the wooden boards 201, 202, 205, and 206 are joined together as shown in FIG. 23(B).

[0084] Furthermore, the worker attaches one solar panel 33 to each of the outer surfaces of the wooden boards 203 and 204, brings the wooden boards 203 and 204 close to the computer system 30 in their respective predetermined orientations, and wires the two solar panels 33 to the computer system 30. Then, the wooden boards 203 and 204 are joined to the wooden boards 201, 202, 205, and 206 as follows.

[0085] The worker fits the protrusions 205c of the wooden board 205 and the protrusions 206c of the wooden board 206 into the grooves 203a and 203b of the wooden board 203, respectively, and fits the male parts 203c and 203d of the wooden board 203 into the female parts 201c of the wooden board 201 and the female parts 202c of the wooden board 202, respectively.

[0086] Similarly, the worker fits the protrusions 205d of the wooden board 205 and the protrusions 206d of the wooden board 206 into the grooves 204a and 204b of the wooden board 204, respectively, and fits the male parts 204c and 204d of the wooden board 204 into the female parts 201d of the wooden board 201 and the female parts 202d of the wooden board 202, respectively.

[0087] Through the above steps, the six wooden boards 201 to 206 are joined together to complete the assembly of the wooden casing 2, and the installation of the solar panel 33, the first antenna 31, and the second antenna 32 is also completed.

[0088] In particular, the wooden boards 201-204 are joined using a hidden dovetail joint. The hidden dovetail joint is one of the traditional joint techniques for joining two pieces of wood together, as described in the "Hanburi Kobo" webpage "Hidden Dovetail Joints" (https: / / www.haburikobo.com / knowledge / k0008.htm) and the "Life Navi" webpage "58 Types of Basic Wood Joints" (https: / / kagu-diy.com / diy / mokkou / setugou). This technique prevents warping, creating a strong joint, and also hides the joints for a clean appearance.

[0089] In this embodiment, as shown in Figure 24 (A), the female part 202d of the wooden board 202 has three recesses (mortises) 202n, 202o, 202p and a flange 202m, and the male part 203c of the wooden board 203 has three protrusions (dovetail tenons) 203n, 203o, 203p and a flange 203m.

[0090] The worker joins the wooden boards 202 and 203 by fitting the protrusions 203n, 203o, and 203p into the recesses 202n, 202o, and 202p, respectively. At this time, the dovetail joint becomes invisible, as shown in Figure 24(B). As shown in Figures 23(A) and 23(B), the protrusions 206b and 206c of the wooden board 206 are fitted into the grooves 202b and 203b, respectively, and the protrusions 205b and 205c of the wooden board 205 are fitted into the grooves 202a and 203a, respectively.

[0091] Similarly, the wooden boards 201 and 203, the wooden boards 201 and 204, and the wooden boards 202 and 204 are joined by fitting one protrusion (dovetail tenon) into each of the three recesses (mortises).

[0092] As described above, the wooden boards 201 to 204 and 206 have 12 missing portions 201i, 201j, 202i, 202j, 203i, 203j, 204i, 204j, 206e, 206f, 206g, and 206h at the positions shown in Figures 13 to 20, 21, or 22. Therefore, the wooden casing 2 has small missing portions near four of its eight vertices.

[0093] 2.4 Assembly of the protector 36 and attachment to the wooden housing 2, etc. FIG. 25 is a diagram showing an example of the protector 36. FIG. 26 is a diagram showing an example of a frame 361. FIG. 27 is a diagram showing an example of a frame 362. FIG. 28 is a diagram showing an example of legs 363 and 364. FIG. 29 is a diagram showing an example of legs 365 and 366. FIG. 30 is a diagram showing examples of fixing members 367 to 369. FIG. 31 is a diagram showing an example of a corner 362d of the frame 362. FIGS. 32 and 33 are diagrams showing an example of a procedure for assembling the protector 36. FIG. 34 is a diagram showing an example of the positional relationship between the Y-direction coupler 34, the X-direction coupler 35, and the protector 36.

[0094] When the assembly of the wooden casing 2 is completed, the worker attaches the protector 36 to the wooden casing 2 and the Y-direction connector 34 while assembling the protector 36 .

[0095] The protector 36 protects the wooden casing 2 by covering 12 edges of the wooden casing 2 as shown in Figures 1(A) and (B), and as shown in Figure 25, it is composed of frames 361 and 362 on the +Y side and -Y side, respectively, and four legs 363 to 366.

[0096] As shown in FIG. 26, the frame 361 is a frame having four beams, and cylindrical holes 361e to 361w are provided at any of the four corners 361a to 361d.

[0097] As shown in FIG. 27, the frame 362 is a frame having four beams, and cylindrical holes 362e to 362w are provided at any of the four corners 362a to 362d.

[0098] The frames 361 and 362 also serve as rails for sliding inside the satellite mount case when the satellite 1 is deployed from the satellite mount case. The satellite mount case is a case that has a small satellite deployment mechanism called "J-SSOD" (JEM (JEM Small Satellite Orbital Deployer)), and is used to mount a CubeSat-compliant satellite and place the satellite into orbit in outer space.

[0099] As shown in FIG. 28A, the leg 363 is composed of a pillar 363a, a first connecting portion 363b, and a second connecting portion 363c, and is provided with screw holes 363d to 363g.

[0100] As shown in FIG. 28B, the leg 364 is composed of a post 364a, a first connecting portion 364b, and a second connecting portion 364c, and is provided with screw holes 364d, 364e, and holes 364f, 364g.

[0101] As shown in FIG. 29A, the leg 365 is made up of a pillar 365a, a first connecting portion 365b, and a second connecting portion 365c, and is provided with screw holes 365d to 365h.

[0102] As shown in FIG. 29B, the leg 366 is made up of a post 366a, a first connecting portion 366b, and a second connecting portion 366c, and is provided with screw holes 366d to 366f, a hole 366g, and a large screw hole 366h.

[0103] Furthermore, fixing members 367 to 369 shown in Figures 30(A) to 30(C) are used to fix the deployment switch between the corner of the frame and the leg. For example, as shown in Figure 31(A), the deployment switch 306 is provided in corner 362d of the frame 362. As shown in Figure 31(B), the deployment switch 306 is fitted into corner 362d and fixed by fixing member 367. Then, a leg 366 is attached to fixing member 367.

[0104] As shown in Fig. 32(A), the worker sets fixing members 368, 367 at corners 362b, 362d of frame 362, respectively. At this time, as illustrated in Fig. 31(A) and (B), one deployment switch 306 is fixed between corners 362b, 362d of frame 362 and fixing members 368, 367. Hereinafter, the deployment switches 306 fixed to corners 362b, 362d, respectively, will be referred to as "deployment switch 3061" and "deployment switch 3062."

[0105] The deployment switches 3061 and 3062 have protrusions for switching the power on and off, which protrude to the outside of the satellite 1 through holes 362v and 362w in the corners 362b and 362d, respectively.

[0106] At this time, hole 362e (see FIG. 27) in corner 362b of frame 362 is connected to hole 368a (see FIG. 30B) of fixing member 368. Also, hole 362f in corner 362d of frame 362 is connected to hole 367a (see FIG. 30A) of fixing member 367.

[0107] The worker inserts screw 36va into holes 362e and 368a from the -Y side and tightens it, and inserts screw 36vb into holes 362f and 367a and tightens it.

[0108] Furthermore, as shown in FIG. 32(B), the worker fits the wooden casing 2 into the frame 362, and fits the legs 363, 364, 365, and 366 into the corners 362a, 362b, 362c, and 362d, respectively.

[0109] At this time, hole 362g in corner 362a of frame 362 is connected to screw hole 363d in leg 363 (see FIG. 28A). Hole 362h in corner 362b of frame 362 is connected to screw hole 364d in leg 364 (see FIG. 28B). Hole 362i in corner 362c of frame 362 is connected to screw hole 365d in leg 365 (see FIG. 29A). Hole 362j in corner 362d of frame 362 is connected to screw hole 366d in leg 366 (see FIG. 29B).

[0110] From the +X side, the worker inserts and tightens screw 36vc into hole 362g and screw hole 363d, and screw 36vd into hole 362h and screw hole 364d. Furthermore, from the -X side, the worker inserts and tightens screw 36ve into hole 362i and screw hole 365d, and screw 36vf into hole 362j and screw hole 366d.

[0111] Furthermore, a hole 362k in a corner 362a of the frame 362 is connected to a screw hole 363e in the leg 363. A hole 362m in a corner 362c of the frame 362 is connected to a screw hole 365e in the leg 365.

[0112] The worker inserts screw 36vg from the -Y side into hole 362k and screw hole 363e and tightens it, and inserts screw 36vh into hole 362m and screw hole 365e and tightens it.

[0113] Furthermore, the worker interposes the deployment switch 3063 and the fixing member 369 between the frame 361 and the leg 364 as shown in FIG. 33(A), and fits the legs 363 to 366 into the frame 361 as shown in FIG. 33(B).

[0114] At this time, the deployment switch 3063 is fixed to the frame 361 by the fixing member 369, and the protrusion protrudes from the hole 361w of the frame 361. Also, the hole 361e (see FIG. 26) in the corner 361b of the frame 361 is connected to the hole 369a (see FIG. 30C) of the fixing member 369. The worker inserts the screw 36vi into the holes 361e and 369a from the +Y side and tightens them.

[0115] Furthermore, hole 361f in corner 361a of frame 361, hole 361g in corner 361b, hole 361h in corner 361c, and hole 361i in corner 361d are connected to screw hole 363f in leg 363, screw hole 364e in leg 364, screw hole 365f in leg 365, and screw hole 366e in leg 366, respectively.

[0116] The worker inserts and tightens screw 36vj into hole 361f and screw hole 363f from the +X side, and screw 36vk into hole 361g and screw hole 364e. Also, from the -X side, the worker inserts and tightens screw 36vm into hole 361h and screw hole 365f, and screw 36vn into hole 361i and screw hole 366e.

[0117] Furthermore, holes 361j in corner 361a, 361k in corner 361c, and 361m in corner 361d of frame 361 are connected to screw holes 363g, 365g, and 366f in leg 363, leg 365, and leg 366, respectively.

[0118] The worker inserts and tightens screw 36vo from the +Y side into hole 361j and screw hole 363g, inserts and tightens screw 36vp into hole 361k and screw hole 365g, and inserts and tightens screw 36vq into hole 361m and screw hole 366f.

[0119] Furthermore, holes 367b, 368b, and 369b (see FIGS. 30A, 30B, and 30C) of fixing members 367, 368, and 369 are connected to hole 366g of leg 366 and holes 364f and 364g of leg 364, respectively. An operator secures fixing member 367 to leg 366 by inserting screws into holes 367b and 366g and tightening them (see FIG. 31). Similarly, fixing member 368 is secured to leg 364 by inserting screws into holes 368b and 364f and tightening them, and fixing member 369 is secured to leg 364 by inserting screws into holes 369b and 364g and tightening them.

[0120] The above steps complete the assembly of the protector 36 and the attachment of the protector 36 to the wooden casing 2. At this time, the Y-direction couplers 341 to 344, the X-direction couplers 351 to 354, and the protector 36 have the positional relationship shown in FIG.

[0121] 2.5 Connection of the Wooden Boards 201 to 204 with the Y-Direction Connector 34, etc. FIG. 35 is a diagram showing an example of a method for connecting the wooden boards 201 to 204 with the Y-direction connector 34. In FIG.

[0122] After the assembly of the protector 36 and the attachment of the protector 36 to the wooden casing 2 are completed, the worker connects the wooden boards 201 to 204 to the Y-direction connector 34 .

[0123] By the way, when the attachment of the protector 36 to the wooden housing 2 is completed, the holes 361n, 361o, 361p, 361q (see Figure 26) of the frame 361 are respectively connected to the holes 201e, 201g of the wooden board 201, the holes 202e, 202g of the wooden board 202 (see Figures 13 and 15), the screw hole 34kc of the first connecting portion 34fc of the Y-direction coupler 343, the screw hole 34kd of the first connecting portion 34fd of the Y-direction coupler 344, the screw hole 34kb of the first connecting portion 34fb of the Y-direction coupler 342, and the screw hole 34ka of the first connecting portion 34fa of the Y-direction coupler 341 (see Figures 10(A) to (D)).

[0124] Holes 361r, 361s, 361t, and 361u of the frame 361 are respectively connected to holes 203e, 203g, 203f, and 203h (see Figure 17) of the wooden board 203, and to the screw hole 34ic of the first connection portion 34fc of the Y-direction coupler 343, the screw hole 34id of the first connection portion 34fd of the Y-direction coupler 344, the screw hole 34ib of the first connection portion 34fb of the Y-direction coupler 342, and the screw hole 34ia of the first connection portion 34fa of the Y-direction coupler 341.

[0125] Holes 362n, 362o, 362p, and 362q (see Figure 27) of the frame 362 are respectively connected to holes 201f and 201h of the wooden board 201, holes 202f and 202h of the wooden board 202, and screw hole 34tc of the second connection portion 34gc of the Y-direction coupler 343, screw hole 34td of the second connection portion 34gd of the Y-direction coupler 344, screw hole 34tb of the second connection portion 34gb of the Y-direction coupler 342, and screw hole 34ta of the second connection portion 34ga of the Y-direction coupler 341.

[0126] Holes 362r, 362s, 362t, and 362u of the frame 362 are respectively connected to holes 204e, 204g, 204f, and 204h (see Figure 19) of the wooden board 204 and holes 34rc of the second connection portion 34gc of the Y-direction coupler 343, holes 34rc of the second connection portion 34gc of the Y-direction coupler 344, holes 34rb of the second connection portion 34gb of the Y-direction coupler 342, and holes 34ra of the second connection portion 34ga of the Y-direction coupler 341.

[0127] That is, the 16 holes 361n to 361u and 362n to 362u of the protector 36 are connected to the holes of any one of the wooden boards 20 and the holes of any one of the Y-direction connectors 34 .

[0128] As shown in Figure 35, the worker inserts screws 36wa to 36wq one by one through the holes on the outside of the protector 36, passes them through the holes in the wooden board 20 connected to it, and tightens them into the holes in the Y-direction connector 34 connected to it.

[0129] The diameter of the screw heads of the screws 36wa to 36wq is larger than the diameter of the holes on the outside of the protector 36, so the screw heads stop at the holes. The screws 36wa to 36wq simply pass through the holes in the wooden board 20, but are not tightened into the holes in the wooden board 20.

[0130] As a result, the four shafts running in the Y-axis direction, i.e., the four Y-direction couplers 341 to 344, are connected to the two wooden boards 20 facing each other in the Y-axis direction, i.e., the wooden boards 203 and 204. Furthermore, since the four X-direction couplers 35 are fixed to the four Y-direction couplers 341 to 344, the four X-direction couplers 35 are connected to the two wooden boards 20 facing each other in the X-axis direction, i.e., the wooden boards 201 and 202. Therefore, loosening of the structure of the wooden housing 2 can be suppressed.

[0131] If the wooden board 20 (wood) and the protector 36 (aluminum material) were glued or screwed together, there is a concern that a shear force would act on the joint due to differences in the thermal expansion coefficients of the two materials or swelling and shrinkage caused by changes in the moisture content of the wood, causing deformation of the wooden housing 2. However, by attaching the protector 36 to the wooden housing 2 using the method described above, the effects of the shear force can be avoided. In addition, the tightening force of the wooden housing 2 can be adjusted by adjusting the tightening torque of the screws.

[0132] Then, the worker inserts the spring plunger 305 for turning the power of the satellite 1 on and off into the hole 361v of the frame 361 and the screw hole 366h of the leg 366 (see FIG. 29(B)) and screws it in place.

[0133] The above steps complete the assembly of the satellite 1. The satellite 1 is then housed in a satellite mounting case.

[0134] Then, the protrusion 305a of the spring plunger 305 is pushed into the switch body 305b by another satellite or the door of the satellite mounting case, etc. At this time, the protrusions of the deployment switches 3061 to 3063 are also pushed in, and in conjunction with this, the power supply of the satellite 1 is turned off.

[0135] 3. Operation of the Satellite 1 in Space The satellite 1 is transported by rocket to a space station (for example, the ISS (International Space Station)) while housed in the satellite mount case, and then released into space. It is then released from the satellite mount case.

[0136] This causes the protrusion 305a of the spring plunger 305 to pop out to its original position. This ensures a certain distance from other satellites mounted in the satellite mount case, preventing collisions. The protrusions of the deployment switches 3061 to 3063 also pop out to their original positions, turning on the power to the satellite 1.

[0137] The satellite 1 then executes predetermined processing based on calculations by the main CPU of the computer system 30. Examples of the predetermined processing include a process for returning the antenna elements 31 a and 31 b (see FIG. 1A) of the first antenna 31 to a straight line, and communication with a ground station.

[0138] Communication with the ground station may be bidirectional communication using either the first antenna 31 or the second antenna 32. For example, the satellite 1 receives a packet transmitted from the ground station using the first antenna 31 and processes the data. Then, the first antenna 31 transmits a Morse code representing the call sign of the ground station in the same frequency band as a CW (Continuous Wave) signal.

[0139] 4. Effects and Variations of the Present Embodiment 4.1 Effects of the Present Embodiment As described above, the wooden casing 2 was manufactured by joining the wooden boards 20 with hidden dovetail joints. In outer space, the difference in thermal expansion coefficient between wood and metal is much greater than on Earth, making it difficult to assemble a wooden structure using metal fasteners such as bolts and screws. However, by employing this technique, the wooden casing 2 can be realized without using metal fasteners.

[0140] Furthermore, wooden boards 201 to 204 of the six wooden boards 20 were joined by a concealed dovetail joint, but wooden boards 205 and 206 were joined to the wooden boards 201 to 204 by simply fitting their respective tongues into the grooves of the wooden boards 201 to 204. This allows for a larger tolerance for each wooden board 20 than when all six wooden boards 20 are joined by a concealed dovetail joint.

[0141] However, this tends to cause loosening of the wooden casing 2. Therefore, in this embodiment, the two wooden boards 203 and 204 facing each other in the Y-axis direction are connected to four Y-direction couplers 34, and the two wooden boards 201 and 202 facing each other in the X-axis direction are connected to four X-direction couplers 35, thereby preventing loosening.

[0142] Furthermore, by using the wooden housing 2, that is, a housing made of wood, as the housing of the artificial satellite 1, the following effects are achieved.

[0143] Since the majority of conventional satellites are made of aluminum, if they are re-entered into the atmosphere after their operational life is over and burned up to prevent them from becoming a source of space debris, they could produce tiny alumina particles that could pollute the middle atmosphere. If the remaining alumina particles fall into the ocean, they could also pollute the ocean.

[0144] In contrast, the majority of the structural materials used in Satellite 1 are wood, which significantly reduces the generation of fine alumina particles compared to conventional methods, thereby reducing the possibility of pollution of the middle atmosphere. When wood is burned, it mainly produces water and carbon dioxide, but water is harmless and carbon dioxide has a smaller impact on the environment than alumina particles. Even if any wood that is not completely burned falls into the ocean, it will eventually rot and decompose, reducing the possibility of marine pollution.

[0145] In this way, the artificial satellite 1 can reduce the burden on the global environment that occurs when it is disposed of after its operation has ended, compared to conventional methods.

[0146] Furthermore, even if wood is exposed to outer space for a long period of time, ultraviolet rays will simply decompose it into atoms such as carbon, hydrogen, and oxygen. Therefore, even if the satellite 1 is operated in outer space for a long period of time, the generation of harmful fine particles can be reduced compared to conventional methods.

[0147] Furthermore, since the wooden casing 2 is used, a small antenna such as the second antenna 32 can be arranged inside the wooden casing 2 and is less susceptible to external influences, so that even antennas with weak mechanical strength or susceptible to ultraviolet rays can be used as antennas, improving the degree of freedom in antenna production.

[0148] Furthermore, since it becomes easy to install a plurality of antennas, it is possible to improve the stability and reliability of communication.

[0149] Furthermore, the wooden housing 2 reduces the impact on antenna characteristics, making it possible to use various types of antennas. For example, it is possible to configure a Yagi-Uda antenna by adding a director or reflector to a dipole antenna, improving antenna efficiency and stabilizing communications. Furthermore, necessary communications can be performed with lower power consumption, which allows for weight reduction and increased operating time.

[0150] In this embodiment, the satellite 1 is provided with a first antenna 31 and a second antenna 32 as antennas for communication with a ground station. Therefore, even if the antenna elements 31a and 31b of the first antenna 31 do not return to a straight line after the satellite 1 is released into space, communication can be performed using the second antenna 32. Alternatively, if the second antenna 32 is malfunctioning, communication can be performed using the first antenna 31.

[0151] 4.2 Modifications The above description is an example of the artificial satellite 1. The present invention can also be applied to the artificial satellite 1 modified as follows.

[0152] (1) Joints In this embodiment, the wooden boards 201 to 204 are joined using a rectangular hidden dovetail joint, but they may also be joined using other techniques. For example, they may be joined using a rectangular hidden dovetail joint with a 90-degree angle between the joints of the flanges, as described in an article dated August 22, 2020, on the Facebook page "Kyoto Daito Urushi Mokkou" (https: / / www.facebook.com / ohigashi.urusi.mokkou / posts / 2856050117958567).

[0153] Alternatively, not only the wooden boards 201 to 204 but also the wooden boards 205 and 206 may be joined to the wooden boards 201 to 204 by a hidden dovetail joint or other jointing techniques.

[0154] (2) Attitude Control Means The satellite 1 may be equipped with one magnetic torquer each corresponding to the X-axis, Y-axis, and Z-axis, and the attitude of the satellite 1 may be controlled by adjusting the current to each magnetic torquer based on information measured by a geomagnetic sensor. The Despin control method may then be used to dissipate the rotational kinetic energy of the satellite 1. Existing magnetic torquers may be used. For example, a CUBETORQUER GEN2 CR0002 may be used. Attitude control experiments may also be performed.

[0155] (3) Notches and Holes in the Wooden Board 20 When exposed to a vacuum, wood loses its moisture and deforms. This deformation occurs perpendicular to the wood fibers. Therefore, to prevent the wooden board 20 from cracking, notches should not be made in the direction parallel to the fibers of the wooden board 20. Furthermore, when making square holes, it is desirable to round the corners to prevent stress concentration.

[0156] (4) Size In this embodiment, an artificial satellite measuring 100 mm x 100 mm x 114 mm has been described as an example of the artificial satellite 1, but the present invention can also be applied to artificial satellites of other sizes. For example, the artificial satellite may be 100 mm x 100 mm x 100 mm in size, or may be a 1.5U class, 2U class, 3U class, or 6U class artificial satellite. Alternatively, the artificial satellite may be a size conforming to a standard other than CubeSat.

[0157] When changing the size to 100 mm x 100 mm x 100 mm, the configuration can be basically the same as that of the satellite 1, except for the length in the Z-axis direction. In the case of a 2U class, it is also sufficient to change the length in the Z-axis direction of each part of the satellite 1. However, it may also be configured as in the satellite 12 described next.

[0158] (5) 2U Class Artificial Satellite Figure 36 is a perspective view showing an example of a 2U class artificial satellite 12. Figure 37 is a six-sided view showing an example of a 2U class artificial satellite 12. Figure 38 is a diagram showing an example of a wooden board used on the +Z side or -Z side.

[0159] The artificial satellite 12 is a 2U class size artificial satellite as shown in Figure 36 or 37. The following description will focus on the differences from the artificial satellite 1. The description of the points in common with the artificial satellite 1 will be omitted.

[0160] 1A and 1B, satellite 12 not only has approximately twice the length of each part of satellite 1 in the Z-axis direction, but also has four pillars 36A-36D at the center of the Z-axis direction. That is, there is one pillar 36A-36D at the center of each of the +X, -X, +Y, and -Y sides. In addition, two rows of slots are provided in backplane 301, allowing approximately twice the number of expansion cards 302 to be installed.

[0161] Since the satellite 12 is larger in size than the satellite 1, it can execute processes for accomplishing more missions than the satellite 1, for example, as follows.

[0162] A strain gauge is installed inside the wooden casing 22 to measure strain inside the wooden casing 22 continuously and in situ. This makes it possible to track changes in the physical properties of the wood in the space environment in real time. Note that the wooden casing 22 is made by joining multiple wooden boards 20 with hidden dovetail joints, and since compressive force is applied in the Y-axis direction by the protector 36, it may not be possible to accurately measure strain. Therefore, a special piece of wood may be installed inside the wooden casing 22, and the strain of this wood may be measured.

[0163] A dielectric sensor is installed inside the wooden casing 22 to measure the dielectric constant of the wooden casing 22 continuously and in situ, thereby enabling real-time tracking of changes in the physical properties of wood in the space environment based on changes in the dielectric constant.

[0164] A digital camera is installed inside the wooden casing 22 and photographs the surface of the wooden casing 22. Then, by analyzing (observing) the photographed surface, it is possible to investigate how the wood surface is changed by atomic oxygen and vacuum ultraviolet rays. After being released from the satellite mount case, the digital camera may be moved to the outside of the wooden casing 22 by a folding arm, and the surface of the wooden casing 22 may be photographed from outside.

[0165] Multiple temperature sensors are installed inside the wooden casing 22, and temperature measurements (multipoint temperature measurements) are performed continuously and in situ at multiple positions inside the casing 22. This allows us to evaluate the thermal insulation properties of wood in space and identify the correlation between temperature changes and the physical properties of the wooden structure (strain, dielectric constant, etc.).

[0166] These mission processes will continue for the medium to long term. The satellite 12 transmits data indicating each measured value to a ground station via CW or FM packets. The ground station determines changes in the physical properties of the wood or the state of the satellite 12 based on the received data, and controls the attitude of the satellite 12. The satellite 12 may also perform two-way communication with amateur radio operators in various countries.

[0167] The processing for these missions can also be performed in the satellite 1 to the extent that it is possible to incorporate the equipment.

[0168] As the wooden boards on the +Z side and -Z side, one of the following is used: a wooden board whose fiber direction is perpendicular to the Z-axis direction, as shown in Figure 38(A), a wooden board whose fiber direction is parallel to the Z-axis direction, as shown in Figure 38(B), or two wooden boards equivalent to the wooden board 205 used in the artificial satellite 1, width-jointed, as shown in Figure 38(C).

[0169] In addition, the overall or individual configurations of the satellite 1, wooden casing 2, computer system 30, Y-direction coupler 34, X-direction coupler 35, and protector 36, the processing content, the processing order, etc. can be modified as appropriate in accordance with the spirit of the present invention.

[0170] 1, 12 Artificial satellite 2 Wooden casing 20 Wooden board 201, 202 Wooden boards facing each other in the X-axis direction 201e to 201h, 202e to 202h Holes (fourth holes) 203, 204 Wooden boards facing each other in the Y-axis direction 203e to 203h, 204e to 204h Holes (second holes) 302 Expansion card 3021, 3022 Expansion card (PCB) 302a to 302d Holes (fifth holes) 302e to 302h Holes (fifth holes) 34 Y-direction coupler (coupler) 34ia to 34id, 34ra to 34rd Screw holes 34ka to 34kd, 34ta to 34td Screw holes (second screw holes) 35 X-direction coupler (second coupler) 36 Protector 361r to 361u, 362r to 362u Holes (first holes) 361n to 361q, 362n to 362q Holes (third holes) 36wa to 36wd, 36wi to 36wn Screws (second screws) 36we to 36wh, 36wn to 36wq Screws

Claims

1. A satellite comprising: a wooden casing constructed by assembling six wooden boards into a rectangular parallelepiped shape, with two of the six wooden boards facing each other in the X-axis direction and two of the six wooden boards facing each other in the Y-axis direction joined with concealed dovetail joints; and four couplers that connect the four pairs of opposing corners of the two wooden boards facing each other in the Y-axis direction to prevent loosening of the wooden casing structure due to shrinkage of the six wooden boards.

2. The satellite according to claim 1, wherein the four couplers are made of stainless steel.

3. A satellite as described in claim 1 or claim 2, comprising a protector that covers the edges of the wooden casing and has first holes at each of the four corners of the +Y side surface and the -Y side surface, wherein each of the two wooden boards facing each other in the Y axis direction has a second hole at each of the four corners, and each of the four couplers has a screw hole at the +Y side end surface and the -Y side end surface, and wherein the four couplers connect the two wooden boards facing each other in the Y axis direction by inserting a screw whose head diameter is larger than the diameter of the first hole through the first hole, passing it through the second hole, and tightening it into the screw hole.

4. The satellite according to claim 3, wherein each of the four couplers has a second screw hole on its +X side end face and a -X side end face, the protector has a third hole on each of the four corners of its +X side face and the four corners of its -X side face, and each of the two wooden boards opposing each other in the X axis direction has a fourth hole on each of its four corners, and second screws having a screw head diameter larger than the diameter of the third holes are inserted through the third holes and passed through the third holes and tightened into the second screw holes.

5. The satellite according to claim 3, wherein the protector is made of aluminum.

6. The satellite according to claim 1 or claim 2, further comprising four second couplers connected to both ends of two pairs of couplers that face each other in the X-axis direction among the four couplers.

7. The satellite according to claim 6, further comprising a PCB (Printed Circuit Board) having fifth holes at each of its four corners, the PCB being attached to the wooden casing by passing the four second couplers through the fifth holes, respectively.

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