Space facility bulkhead structure

Abstract

Provided is a bulkhead structure that that shields a space facility (100) installed in outer space from external space. The bulkhead structure comprises a pressurized wall (11) that hermetically surrounds the space facility (100) such that an internal space (14) of the space facility (100) has a predetermined air pressure, and a protective wall (12) that is provided on the outer peripheral side of the pressurized wall (11) at a gap from the pressurized wall (11), and that protects the outer periphery of the pressurized wall (11). At least part of an outer wall space (15) formed between the pressurized wall (11) and the protective wall (12) is filled with water.

Description

[Technical field]

[0001] The present invention relates to a bulkhead structure for a space facility. [Background technology]

[0002] When high-energy particles (mainly protons) contained in cosmic radiation collide with oxygen and nitrogen atomic nuclei in the Earth's atmosphere, neutron rays are generated and rain down on the ground. Non-Patent Document 1 discloses that neutron rays that rain down on the ground can cause electronic devices placed on the ground to malfunction and burn out circuit elements.

[0003] On the other hand, in space facilities (e.g. manned space facilities) located in outer space, cosmic radiation collides with the outer walls surrounding the facility, generating neutron rays, which then enter the space facility and cause the same phenomenon as described above. Unlike on the ground, in space facilities, there is no attenuation due to passing through the atmosphere. For this reason, the impact of cosmic radiation on electronic devices is greater than on the ground.

[0004] Non-Patent Document 2 discloses that the impact of cosmic radiation on electronic devices can be reduced by taking measures such as using components that are more resistant to cosmic radiation than electronic devices used on the ground, or duplicating the electronic device systems, for electronic devices used in space facilities.

[0005] Non-Patent Document 3 discloses the use of wet towels installed in a space facility as a method for reducing space radiation in the facility. [Prior art documents] [Non-patent literature]

[0006] [Non-Patent Document 1] Shoji and Nishida, "Research on the Space Radiation Destruction Resistance of Power Devices," Institute of Electrical Engineers of Japan, Technical Development Report, 2016 [Non-Patent Document 2] Japan Aerospace Exploration Agency, "Handbook for Space Applications of Space-Divertible Parts," JERG-2-023, May 2015 [Non-Patent Document 3] Kodaira, "Method of reducing space radiation exposure using wet towels during space stays," Isotope News, August 2014 issue Summary of the Invention [Problem to be solved by the invention]

[0007] However, the method disclosed in Non-Patent Document 2 has a problem of high installation costs for electronic devices. In addition, the method disclosed in Non-Patent Document 3 can reduce cosmic radiation to a certain extent, but the effect is small and does not provide a fundamental solution.

[0008] The present invention has been made in consideration of the above circumstances, and an object of the present invention is to provide a bulkhead structure for a space facility capable of attenuating space radiation entering the space facility. [Means for solving the problem]

[0009] One embodiment of the present invention provides a bulkhead structure for a space facility that shields a space facility installed in outer space from external space, and includes a pressurized wall that hermetically surrounds the space facility so that the internal space of the space facility is at a predetermined air pressure, and a protective wall that is spaced apart from the pressurized wall on the outer periphery of the pressurized wall and protects the outer periphery of the pressurized wall, and at least a portion of the outer wall space formed between the pressurized wall and the protective wall is filled with water. Effect of the Invention

[0010] According to the present invention, it is possible to attenuate space radiation entering a space facility. [Brief description of the drawings]

[0011] [Figure 1] FIG. 1 is an explanatory diagram that illustrates a cross section of a space facility equipped with a bulkhead structure according to an embodiment. [Figure 2A] FIG. 2A is an explanatory diagram showing the trajectories of protons when the outer wall space is made a vacuum and the protective wall is irradiated with 100 MeV protons. [Figure 2B] FIG. 2B is an explanatory diagram showing the trajectories of protons when the outer wall space is filled with water and the protective wall is irradiated with 100 MeV protons. [Figure 3A] FIG. 3A is a graph showing the energies of protons and neutrons that passed through two aluminum alloy plates when the space between the plates was made a vacuum and the plates were irradiated with 100 MeV protons. [Figure 3B] FIG. 3B is a graph showing the energies of protons and neutrons that passed through two aluminum alloy plates when the space between the plates was filled with water and the plates were irradiated with 100 MeV protons. [Figure 4A] FIG. 4A is a graph showing the energies of protons and neutrons that passed through two aluminum alloy plates when the space between the plates was made a vacuum and the plates were irradiated with 150 MeV protons. [Figure 4B] FIG. 4B is a graph showing the energies of protons and neutrons that passed through two aluminum alloy plates when the space between the plates was filled with water and the plates were irradiated with 150 MeV protons. [Figure 5A] FIG. 5A is a graph showing the energies of protons and neutrons that passed through two aluminum alloy plates when the space between the plates was made a vacuum and the plates were irradiated with 200 MeV protons. [Figure 5B] FIG. 5B is a graph showing the energies of protons and neutrons that passed through two aluminum alloy plates when the space between the plates was filled with water and irradiated with 200 MeV protons. [Figure 6] FIG. 6 is a graph showing the ratio of protons that passed through the outer wall space when the outer wall space was irradiated with protons having a uniform energy distribution of 1 to 200 [MeV]. [Figure 7] FIG. 7 is an explanatory diagram showing a first embodiment in which the outer wall space is filled with water. [Figure 8]FIG. 8 is an explanatory diagram showing a second embodiment in which the outer wall space is filled with water. [Figure 9] FIG. 9 is an explanatory diagram showing a third embodiment in which the outer wall space is filled with water. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] Hereinafter, an embodiment will be described with reference to the drawings, in which: Fig. 1 is an explanatory diagram that shows a schematic cross section of a space facility equipped with a bulkhead structure according to an embodiment.

[0013] A space facility 100 according to this embodiment is a manned facility installed in space, such as an artificial satellite. As shown in FIG. 1, the space facility 100 is hermetically sealed off from the outside space. The space facility 100 has a cylindrical shape. Therefore, in the cross-sectional view shown in FIG. 1, the space facility 100 has a circular shape. Note that the space facility 100 is not limited to a cylindrical shape, and may have other shapes having a closed space.

[0014] As shown in Fig. 1, a space facility 100 is provided with a pressurized wall 11 having a ring-shaped cross section. The space of the space facility 100 surrounded by the pressurized wall 11 is defined as an internal space 14. The internal space 14 is a closed space surrounded by the pressurized wall 11. The pressurized wall 11 hermetically covers the periphery of the space facility 100 so that the internal space 14 of the space facility 100 is at a predetermined air pressure.

[0015] A protective wall 12 is provided around the outer periphery of the pressurized wall 11 to prevent damage to the pressurized wall 11 due to debris such as trash and wreckage floating in space. The protective wall 12 is provided on the outer periphery side of the pressurized wall 11 with a distance L1 from the pressurized wall 11, and protects the outer periphery of the pressurized wall 11. An outer wall space 15 is provided between the pressurized wall 11 and the protective wall 12. In other words, the periphery of the space facility 100 has a double structure of the pressurized wall 11 and the protective wall 12. The outer wall space 15 is a closed space surrounded by the pressurized wall 11 and the protective wall 12. In this embodiment, the outer wall space 15 is used as a water tank to attenuate cosmic radiation.

[0016] In manned space facilities, drinking water and other water for daily life is used. For example, the supply vehicle "Kounotori 6" that delivers supplies to the International Space Station (ISS) transports 600 liters of drinking water at a time, so there is about 1000 liters of water, including the water that was previously there. In this embodiment, this water is used to attenuate space radiation.

[0017] The pressurized wall 11 and the protective wall 12 are formed of, for example, an aluminum alloy. The aluminum alloy is an alloy in which the strength is increased by adding copper (Cu), manganese (Mn), silicon (Si), magnesium (Mg), zinc (Zn), nickel (Ni), etc. to aluminum.

[0018] 1, the ratio of the internal space 14 to the external wall space 15 does not represent the ratio of the actual space facility 100. To facilitate understanding, the thickness of the external wall space 15, i.e., the distance L1, is exaggerated relative to the internal space 14.

[0019] In this embodiment, at least a portion of the exterior wall space 15 is filled with water, and the filled water suppresses the intrusion of space radiation. The water filled in the exterior wall space 15 is water for daily use, such as drinking water, used in the space facility. In other words, the exterior wall space 15 functions as a water storage tank that stores water to be used in the space facility 100.

[0020] Next, we will explain the attenuation of cosmic radiation when the outer wall space 15 is evacuated and filled with water. Figures 2A and 2B are explanatory diagrams showing the trajectory of protons Pr when the protective wall 12 is irradiated with 100 MeV protons Pr. Figure 2A shows the case when the outer wall space 15 is evacuated, and Figure 2B shows the case when the outer wall space 15 is filled with water.

[0021] As shown in FIG. 2A, when the outer wall space 15 is a vacuum, protons Pr irradiated from outside the protective wall 12 pass through the protective wall 12 and the pressurized wall 11 with almost no attenuation in the outer wall space 15 and enter the internal space.

[0022] On the other hand, as shown in FIG. 2B, when the outer wall space 15 is filled with water, the protons Pr irradiated from outside the protective wall 12 are attenuated by the layer of water filling the outer wall space 15, and hardly penetrate into the internal space.

[0023] 3A to 5B are graphs showing the energies of protons and neutrons passing through two aluminum alloy plates when the space between the two aluminum alloy plates is evacuated and filled with water, in an apparatus in which two aluminum alloy plates are arranged in parallel with a gap of 10 cm to simulate the outer wall space 15. For example, the results can be obtained by performing a simulation using the well-known particle transport simulator "PHITS."

[0024] 3A to 5B, the dashed lines indicate the energies of neutrons, and the solid lines indicate the energies of protons.

[0025] Figures 3A and 3B show the energies of protons and neutrons passing through two aluminum alloy plates when the space between the plates is a vacuum and when the space is filled with water, with the energy of the irradiated protons being 100 MeV.

[0026] As shown in Figure 3A, when the space is a vacuum, the maximum energy of the protons passing through the two aluminum alloy plates reaches 90 [MeV]. In contrast, as shown in Figure 3B, when the space is filled with water, the maximum energy of the protons passing through the two aluminum alloy plates is about 10 [MeV].

[0027] Figures 4A and 4B show the energies of protons and neutrons passing through two aluminum alloy plates when the space between the plates is a vacuum and when the space is filled with water, with the irradiated proton energy set to 150 MeV.

[0028] As shown in Figure 4A, when the space is a vacuum, the maximum energy of the protons passing through the two aluminum alloy plates reaches 140 [MeV]. In contrast, as shown in Figure 4B, when the space is filled with water, the maximum energy of the protons passing through the two aluminum alloy plates is about 100 [MeV].

[0029] Figures 5A and 5B show the energies of protons and neutrons passing through two aluminum alloy plates when the space between the plates is a vacuum and when the space is filled with water, with the energy of irradiated protons being 200 MeV.

[0030] As shown in Figure 5A, when the space is a vacuum, the maximum energy of the protons passing through the two aluminum alloy plates reaches 190 [MeV]. In contrast, as shown in Figure 5B, when the space is filled with water, the maximum energy of the protons passing through the two aluminum alloy plates is about 140 [MeV]. In other words, it can be seen that by filling the space between the two aluminum alloy plates with water, the energy of the protons passing through the two aluminum alloy plates can be significantly reduced.

[0031] Figure 6 is a graph showing the ratio of protons that pass through two aluminum alloy plates when the two aluminum alloy plates are irradiated with protons with a uniform energy distribution of 1 to 200 [MeV]. Curve S1 in Figure 6 shows the case where the space between the two aluminum alloy plates is a vacuum, and curve S2 shows the case where the space is filled with water.

[0032] As can be seen from FIG. 6, when the space is a vacuum (curve S1), there is almost no decrease in protons at 100 [MeV] or higher. In other words, the "proportion of entering protons" shown on the vertical axis is almost 1.0 (100%). In contrast, when the space is filled with water, it can be seen that there are no protons at 140 [MeV] or higher, and even at energies below that, the protons are 0.8 (80%) or less. In other words, by filling the space (external wall space 15 shown in FIG. 1) between two aluminum alloy plates surrounded by two aluminum alloy plates (pressurized wall 11 and protective wall 12 shown in FIG. 1) with water, the number of protons passing through the external wall space 15 and the energy of the protons are attenuated.

[0033] Next, an embodiment in which the outer wall space 15 is filled with water will be described with reference to Figs.

[0034] [First Example] Fig. 7 is an explanatory diagram showing a first embodiment in which the outer wall space 15 is filled with water. In the figure, the hatched area indicates the area filled with water. In the first embodiment, the entire outer wall space 15 is filled with water as shown in Fig. 7. That is, by filling the entire periphery of the internal space 14 of the space facility 100 with water, it is possible to suppress the intrusion of cosmic radiation irradiated from all directions in the external space.

[0035] [Second Example] Fig. 8 is an explanatory diagram showing a second embodiment in which water is filled in the outer wall space 15. In the second embodiment, the inside of the outer wall space 15 is divided into a plurality of divided areas along the circumferential direction as shown in Fig. 8. Specifically, as shown in Fig. 8, a plurality of partition plates 17 (12 in the figure) extending in the axial direction of a cylindrical space facility are installed to divide the inside of the outer wall space 15 into 12 divided areas 18 along the circumferential direction.

[0036] Among these, the divided areas 18 present in the direction in which the cosmic radiation Ra is irradiated are filled with water. In the example shown in FIG. 8, three consecutive divided areas 18-1, 18-2, and 18-3 are filled with water. That is, the outer wall space 15 is divided into a plurality of divided areas 18, and at least one of the divided areas 18 is filled with water. With this configuration, even if the amount of water stored is small relative to the capacity of the outer wall space 15, the cosmic radiation Ra irradiated to the space facility 100 can be efficiently shielded. That is, by recognizing in advance the direction from which the cosmic radiation arrives and filling the divided areas 18 facing the arrival direction with water, the cosmic radiation can be attenuated with a small amount of water. The number of divided areas 18 filled with water is not limited to three, and may be two or less, or four or more.

[0037] 1, the divided areas 18 to be filled with water may be set to a range that forms a predetermined angle with the flight direction of the space facility 100 as the center. For example, if the predetermined angle is 150°, the divided areas 18 in a range that forms 150° with the flight direction of the space facility 100 as the center may be filled with water. That is, the space facility 100 has a cylindrical shape, and water may be filled in the outer wall space 15 in a radial cross section of this cylindrical shape that is within a predetermined angle with the traveling direction (flight direction) of the space facility 100 as the base.

[0038] [Third Example] 9 is an explanatory diagram showing a third embodiment in which water is filled in the outer wall space 15. In the third embodiment, as shown in FIG. 9, an intermediate wall 13 is provided between the pressurized wall 11 and the protective wall 12 in the outer wall space 15, thereby dividing the outer wall space 15 into two in the radial direction. That is, the intermediate wall 13 divides the space between the pressurized wall 11 and the protective wall 12. The space between the pressurized wall 11 and the intermediate wall 13 is defined as a first space 31, and the space between the intermediate wall 13 and the protective wall 12 is defined as a second space 32.

[0039] Furthermore, similarly to the second embodiment described above, by providing partition plates 17, the inside of the first space 31 and the second space 32 are divided into a plurality of divided regions 18 along the circumferential direction.

[0040] Among these, the divided area 18 existing in the direction of irradiation with the cosmic radiation Ra is filled with water. In the example shown in Fig. 9, four divided areas 18-11, 18-12, 18-13, and 18-14 are filled with water. That is, an intermediate wall 13 is further provided to separate the pressurized wall 11 and the protective wall 12, and the first space 31 separated by the pressurized wall 11 and the intermediate wall 13 and the second space 32 separated by the intermediate wall 13 and the protective wall 12 are each divided into a plurality of divided areas 18, and at least one divided area 18 of the divided areas of the first space 31 and the divided areas of the second space 32 is filled with water.

[0041] With this configuration, it is possible to appropriately set areas where the water-filled layer is thick and areas where it is thin, and it is possible to fill water in areas that are irradiated with more cosmic radiation Ra. Therefore, even if the amount of water stored in the outer wall space 15 is small, it is possible to efficiently block the cosmic radiation Ra irradiated to the space facility 100.

[0042] As such, the partition structure of this embodiment is a partition structure that shields a space facility 100 installed in outer space from external space, and comprises a pressurized wall 11 that hermetically covers the periphery of the space facility 100 so that the internal space 14 of the space facility 100 is at a predetermined air pressure, and a protective wall 12 that is arranged on the outer periphery of the pressurized wall 11 at a distance from the pressurized wall 11 and protects the outer periphery of the pressurized wall 11, and at least a portion of the outer wall space 15 formed between the pressurized wall 11 and the protective wall 12 is filled with water.

[0043] This makes it possible to reduce the energy of cosmic radiation entering the internal space 14 of the space facility 100 from outside the space facility 100, thereby preventing malfunctions and damage to elements in electronic devices used in the internal space 14.

[0044] In this embodiment, the outer wall space 15 covered by the pressurized wall 11 and the protective wall 12 is divided into a plurality of divided areas 18, and at least one of the divided areas 18 is filled with water. Therefore, by identifying the direction in which cosmic radiation is irradiated around the space facility 100 and filling the divided areas 18 in this direction with water, even if the amount of water to be filled is small and water cannot be filled into the entire outer wall space 15, the energy of the cosmic radiation can be efficiently reduced.

[0045] 1, in this embodiment, the space facility 100 has a cylindrical shape, and water is filled in an outer wall space 15 within a range of a predetermined angle (e.g., 150°) based on the traveling direction of the space facility 100 in a radial cross section of the cylindrical shape. That is, by filling with water the divided areas 18 that are at a predetermined angle with the traveling direction of the space facility 100 as the center, it is possible to reduce radiation from a direction in which more cosmic radiation is irradiated.

[0046] 9, the present embodiment includes an intermediate wall 13 that divides the space between the pressurized wall 11 and the protective wall 12, and divides a first space 31 between the pressurized wall 11 and the intermediate wall 13 and a second space 32 between the intermediate wall 13 and the protective wall 12 into a plurality of divided areas 18, and at least one of the divided areas 18 of the first space 31 and the divided areas 18 of the second space 32 is filled with water. This allows the thickness of the water to be changed in the radial direction of the cylindrical space facility 100, making it possible to reduce the intrusion of cosmic radiation.

[0047] In this embodiment, the outer wall space 15 is used as a water tank for storing water to be used in the space facility 100. Therefore, water for daily life, which is a necessity in the space facility 100, can be used as water for shielding against cosmic radiation, making it possible to reduce the cost required for using the space facility 100.

[0048] The present invention is not limited to the above-described embodiment, and various modifications are possible within the scope of the present invention. [Explanation of symbols]

[0049] 11 Pressurized wall 12 Protective Wall 13 Intermediate Wall 14 Interior Space 15 External wall space 17 Partition 18 divided areas 31 The First Space 32 The Second Space 100 Space Facility

Claims

1. A bulkhead structure that shields a space facility installed in outer space from external space, a pressurized wall that hermetically surrounds the space facility so that an internal space of the space facility has a predetermined air pressure; a protective wall provided on an outer periphery side of the pressurized wall at a distance from the pressurized wall and protecting the outer periphery of the pressurized wall; Equipped with The outer wall space formed between the pressure wall and the protection wall is divided into a plurality of divided areas by partition plates oriented in a direction intersecting the pressure wall, Filling at least one of the divided areas with water. Bulkhead structure of a space facility.

2. An intermediate wall is provided between the pressure wall and the protection wall, A first space between the pressurized wall and the intermediate wall, and a second space between the intermediate wall and the protective wall are divided into a plurality of divided areas by the partition plates, and at least one of the divided areas of the first space and the divided areas of the second space is filled with water. A bulkhead structure for a space facility according to claim 1.

3. The space facility has a cylindrical shape, and water is filled in the outer wall space within a range of a predetermined angle based on the traveling direction of the space facility in a cross section in a radial direction of the cylindrical shape. A bulkhead structure for a space facility according to claim 1 or 2.

4. The outer wall space is a water tank for storing water to be used in the space facility. A bulkhead structure for a space facility according to claim 1 or 2.

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