A method for processing a spacecraft solar sail and a solar sail

Abstract

The invention relates to a method for processing a spacecraft solar sail and a solar sail, comprising the following steps: spin-coating a bottom layer on a silicon wafer, and then spin-coating a flexible base film on the bottom layer; forming a first deposition area on the flexible base film using a photolithography process, and depositing a thin film electrode in the first deposition area; forming a second deposition area on the overall structure after the thin film electrode deposition using a photolithography process, and then depositing an alloy beam in the second deposition area, wherein the alloy beam is deposited between two adjacent thin film electrodes; forming a third deposition area on the alloy beam using a photolithography process, and depositing a reflective beam in the third deposition area, removing photoresist and a sacrificial layer remaining between the alloy beam and the flexible base film and the thin film electrodes due to the photolithography process, and peeling the flexible base film from the bottom layer so that the flexible base film generates residual stress. The solar sail processed by the processing method of the invention has high bending rigidity and eliminates the need for a supporting mechanism.

Description

Technical Field

[0001] The present invention relates to the field of aerospace technology, and in particular to a method for processing a spacecraft solar sail and a solar sail. Background Art

[0002] The statements herein merely provide background information related to the present invention and do not necessarily constitute prior art.

[0003] Solar sails are key devices for spacecraft propulsion using sunlight pressure. The higher the area-to-mass ratio of a solar sail system, the greater the achievable sunlight pressure acceleration. Solar sail sunlight pressure propulsion technology holds great promise for long-duration, long-distance deep space exploration. Although the thrust provided by sunlight pressure is relatively small, it can still provide sufficient acceleration in the space environment to meet the needs of deep space exploration.

[0004] Research has shown that, given a given spacecraft mass, the larger the effective reflective area of ​​the solar sail and the lower its mass—that is, the greater its surface-to-mass ratio—the greater the light pressure acceleration a solar sail spacecraft can achieve. However, large-area solar sail membranes have low bending stiffness and poor controllable reconfiguration capabilities. Existing research often employs auxiliary support mechanisms to enhance the stiffness of solar sails and ensure reliable deployment and configuration retention. However, these support mechanisms are often more cumbersome than the solar sail membrane itself, significantly limiting the improvement in the solar sail system's surface-to-mass ratio. This, in turn, limits the acceleration of the solar sail spacecraft, impacting the system's deep-space exploration capabilities. Summary of the Invention

[0005] In view of the shortcomings of the existing technology, the purpose of the present invention is to provide a method for processing a spacecraft solar sail, which avoids the use of an auxiliary support structure to enhance the rigidity of the solar sail.

[0006] In order to achieve the above object, the present invention is implemented through the following technical solutions:

[0007] In a first aspect, an embodiment of the present invention provides a method for manufacturing a spacecraft solar sail, comprising the following steps:

[0008] Spin coating a bottom layer on a silicon wafer, and then spin coating a flexible base film on the bottom layer;

[0009] forming a first deposition area on the flexible base film using a photolithography process, and depositing a thin film electrode in the first deposition area;

[0010] A second deposition area is formed on the overall structure after thin film electrode deposition using a photolithography process, and then an alloy beam is deposited in the second deposition area, wherein the alloy beam is deposited between two adjacent thin film electrodes;

[0011] A third deposition area is formed on the alloy beam using a photolithography process, and a reflective beam is deposited in the third deposition area.

[0012] The photoresist and sacrificial layer remaining between the alloy beam and the flexible base film and the thin film electrode due to the photolithography process are removed, and the flexible base film is peeled off from the bottom layer to generate residual stress in the flexible base film.

[0013] Optionally, the flexible base film is a polyimide film.

[0014] Optionally, the thin film electrode is made of a metal material that expands when heated, preferably aluminum.

[0015] Optionally, a photoresist is spin-coated on the flexible base film, and photolithography is performed. After exposure and development, a first deposition area is formed. After the thin film electrode deposition is completed, the exposed photoresist outside the first deposition area is removed.

[0016] Optionally, the alloy beam is made of a metal material that shrinks when heated, preferably a nickel-titanium shape memory alloy.

[0017] Optionally, a sacrificial layer is sputtered and photoresist is spin-coated in sequence on the overall structure formed after depositing the flexible base film, and photolithography is performed. After exposure and development, a remaining sacrificial layer and photoresist are formed. Then, photoresist is spin-coated again and photolithography is performed. After exposure and development, a second deposition area is formed, and an alloy beam is deposited in the second deposition area.

[0018] Optionally, the reflective beam is made of a metal material that expands when heated, preferably aluminum.

[0019] Optionally, after removing the excess parts in the alloy beam and the excess exposed photoresist generated during the photolithography of the second deposition area, spin-coat the photoresist on the formed overall structure, perform photolithography, and form a third deposition area on the upper surface of the alloy beam after exposure and development, and deposit the reflective beam in the third deposition area.

[0020] In a second aspect, an embodiment of the present invention provides a solar sail, which is manufactured using the solar sail processing method described in the first aspect.

[0021] Optionally, the flexible base film of the solar sail adopts a cross-shaped structure, and accordingly, the thin film electrode is an L-shaped structure, with four thin film electrodes arranged. The corners of the four thin film electrodes are arranged facing each other so that the four thin film electrodes are distributed in a cross shape on the flexible base film and a cross-shaped gap is formed between the four thin film electrodes, which is concentric with the flexible base film, and multiple alloy beams are arranged between the relative parts of two adjacent thin film electrodes.

[0022] The beneficial effects of the present invention are as follows:

[0023] 1. The solar sail processed by the present invention can generate residual stress in the flexible base film after peeling it from the bottom layer, inducing the solar sail to bend, thereby achieving the purpose of improving the bending stiffness. No support structure is required, avoiding limiting the increase in acceleration of the solar sail spacecraft and not affecting the deep space exploration capability of the solar sail system, thereby effectively improving the surface-to-mass ratio of the solar sail system.

[0024] 2. The solar sail of the present invention is provided with four thin-film electrodes distributed in a cross shape. The four thin-film electrodes can be independently loaded with voltage to achieve the regulation of the solar sail configuration. Loading voltage to different thin-film electrodes can produce different configurations, which can be used for attitude adjustment and orbit adjustment. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] The accompanying drawings, which constitute a part of the present invention, are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute improper limitations on the present invention.

[0026] Figure 1 This is a flow chart of the processing method of Example 1 of the present invention;

[0027] Figure 2 This is a schematic diagram of the overall structure of Example 2 of the present invention before stiffness enhancement;

[0028] Figure 3 This invention Figure 2 A-direction cross-sectional diagram;

[0029] Figure 4 After the passive deployment of embodiment 2 of the present invention Figure 2 A-direction cross-sectional diagram;

[0030] Figure 5 This is a schematic diagram of the overall structure after active reconstruction in Example 2 of the present invention;

[0031] Figure 6 After the active reconstruction of embodiment 2 of the present invention Figure 2 A-direction cross-sectional diagram;

[0032] Figure 7 This is a schematic diagram of the overall structure of embodiment 2 of the present invention in the posture adjustment state;

[0033] Figure 8 This is a schematic diagram of the overall structure of Example 2 of the present invention in the track adjustment state;

[0034] Figure 9 This is a schematic diagram of the overall structure of Example 2 of the present invention in a high-efficiency track adjustment state;

[0035] Among them, 1. silicon wafer, 2. bottom layer, 3. flexible base film, 4. photoresist, 5. exposed photoresist, 6. thin film electrode, 7. sacrificial layer, 8. photoresist, 9. photoresist, 10. exposed photoresist, 11. alloy beam, 12. exposed photoresist, 13. photoresist, 14. exposed photoresist, 15. reflective beam, 16. first sail blade, 17. second sail blade, 18. third sail blade, 19. fourth sail blade, 20. first thin film electrode, 21. second thin film electrode, 22. third thin film electrode, 23. fourth thin film electrode. DETAILED DESCRIPTION

[0036] Example 1

[0037] This embodiment provides a method for manufacturing a spacecraft solar sail. Figure 1 As shown, the following steps are included:

[0038] Step 1: Spin-coat a bottom layer 2 on a silicon wafer 1 , and then spin-coat a flexible base film 3 on the bottom layer 2 .

[0039] In this embodiment, the bottom layer 2 is made of polydimethylsiloxane (PDMS), and the flexible base film 3 is made of polyimide (PI) film.

[0040] Step 2: Use a photolithography process to form a first deposition area on the flexible base film, and deposit a thin film electrode in the first deposition area.

[0041] The specific steps include:

[0042] Step 2.1: Spin-coat a photoresist 4 on the upper surface of the polyimide film, then place a first mask on the upper surface of the spin-coated photoresist 4, and then perform photolithography using ultraviolet irradiation. After exposure and development, remove the photoresist portion irradiated by ultraviolet light to form a first deposition area.

[0043] In this embodiment, there are multiple, preferably four, first deposition areas. The polyimide film is cross-shaped. Each branch of the polyimide film has two first deposition areas. The portion between the two first deposition areas is the exposed photoresist 5 .

[0044] Step 2.2: Physically depositing a thin film electrode 6 in the first deposition area.

[0045] In this embodiment, in order to improve the reflectivity of the solar sail surface, the thin film electrode 6 is made of a metal material that expands when heated, preferably, aluminum, which has a good ability to reflect sunlight.

[0046] Step 2.3: Manually remove the exposed photoresist 5 between the two first deposition areas.

[0047] Step 3: After the thin film electrode deposition is completed, a second deposition area is formed on the overall structure using a photolithography process, and then an alloy beam is physically deposited in the second deposition area.

[0048] The specific steps include:

[0049] Step 3.1: After step 2.3, a sacrificial layer 7 and a spin-coated photoresist 8 are sequentially sputtered on the upper surface of the overall structure formed.

[0050] In this embodiment, the sacrificial layer is made of polysilicon.

[0051] Step 3.2: Place the second mask plate, and then use ultraviolet light to perform photolithography. After exposure and development, remove the sacrificial layer and photoresist parts on both sides, forming a sacrificial layer and photoresist left in the middle after exposure.

[0052] Step 3.3: Spin-coat photoresist 9 on the upper surface of the overall structure after step 3.2.

[0053] Step 3.4: Place a third mask on the upper surface of the photoresist completed in step 3.3, and perform photolithography using ultraviolet irradiation to form a second deposition area. The second deposition area includes the upper surface of the photoresist 10 after exposure in step 3.2, the upper surface portions of the thin film electrodes on both sides thereof, and the upper surface of the remaining photoresist spin-coated in step 3.3 after exposure at both ends.

[0054] Step 3.5: Physically depositing the alloy beam 11 in the second deposition area.

[0055] In this embodiment, the alloy beam 11 is made of a metal material that shrinks when heated. Preferably, the alloy beam 11 is made of a nickel-titanium shape memory alloy material.

[0056] Step 4: A third deposition area is formed on the alloy beam using a photolithography process, and a reflective beam is physically deposited in the third deposition area.

[0057] The specific steps include:

[0058] Step 4.1: Remove the excess portion of the exposed photoresist 12 and the alloy beam 11 deposited on the upper surface thereof at the two end portions after the exposure, which was spin-coated in step 3.3.

[0059] Step 4.2: After step 4.1, a photoresist 13 is spin-coated on the surface of the overall structure formed.

[0060] Step 4.3: Place the fourth mask plate, and then use ultraviolet irradiation for photolithography, and form a fourth deposition area after exposure and development, wherein the fourth deposition area is a set area on the upper surface of the alloy beam 11 and the upper surface of the exposed photoresist 14 on both sides of the set area.

[0061] Step 4.4: Physically depositing the reflective beam 15 in the fourth deposition area.

[0062] In this embodiment, in order to improve the reflectivity of the solar sail surface, the reflective beam 15 is made of a metal material that expands when heated. Preferably, the reflective beam 15 is made of metal aluminum, which has a better ability to reflect sunlight.

[0063] Step 5: Manually remove the excess portion of the exposed photoresist 14 and the reflective beam 15 on its upper surface produced in step 4.3, then remove the exposed sacrificial layer and photoresist retained in step 3.2 below the alloy beam and between the alloy beam and the flexible base film and thin film electrode, and then peel the flexible base film 3 from the polydimethylsiloxane to form a solar sail prototype.

[0064] The flexible base film after peeling has residual stress inside. This residual stress causes the flexible base film and thin film electrode of the solar sail to bend downward, and the double-layer beam structure formed by the alloy beam and the reflective beam to bend upward. The residual stress induces the solar sail to unfold along the thickness direction, thereby improving the bending stiffness of the solar sail. Without introducing a supporting mechanism, the configuration of the high surface-to-mass ratio solar sail is effectively maintained, avoiding the increase in acceleration that limits the solar sail spacecraft and does not affect the deep space exploration capability of the solar sail system.

[0065] Example 2

[0066] This embodiment provides a solar sail, which is processed using the spacecraft solar sail processing method described in Example 1.

[0067] In this embodiment, Figure 2-Figure 3 As shown, the flexible base film adopts a cross-shaped structure and has four sail blades, namely a first sail blade 16, a second sail blade 17, a third sail blade 18 and a fourth sail blade 19.

[0068] Correspondingly, there are four thin film electrodes, and the thin film electrodes adopt an L-shaped structure, namely a first thin film electrode 20 , a second thin film electrode 21 , a third thin film electrode 22 and a fourth thin film electrode 23 .

[0069] Four thin film electrodes are arranged on the upper surface of the flexible base film, wherein the four thin film electrodes are arranged in a cross shape, and a cross-shaped gap concentric with the flexible base film is formed between the four thin film electrodes.

[0070] Specifically, the first thin film electrode 20 is distributed along the outer edges of the first sail blade 16 and the second sail blade 17, the second thin film electrode 21 is distributed along the outer edges of the second sail blade 17 and the third sail blade 18, the third thin film electrode 22 is distributed along the outer edges of the third sail blade 18 and the fourth sail blade 19, and the fourth thin film electrode 23 is distributed along the outer edges of the fourth sail blade 19 and the first sail blade 16.

[0071] A plurality of alloy beams 11 are arranged between two thin film electrode parts arranged opposite to each other on the same sail blade. The plurality of alloy beams are arranged in an array along the length direction of the sail blade.

[0072] like Figure 4-Figure 5 As shown, there is residual stress inside the flexible base film after peeling. This residual stress causes the flexible base film and the thin film electrode of the solar sail to bend downward, and the double-layer beam structure formed by the alloy beam and the reflective beam to bend upward. The residual stress induces the solar sail to passively unfold along the thickness direction.

[0073] like Figure 6 As shown, the double-layer beam formed by the thin film electrode, the alloy beam 11 and the reflective beam 15 constitutes an electrical circuit. When different voltages are loaded on both sides of the alloy beam 11, current will be generated on the alloy beam 11 and the reflectivity beam 15, which will generate Joule heat, causing the alloy beam to shrink due to the shape memory effect, while the high reflectivity beam will expand due to the heat. Due to the mismatch effect of the thermal expansion coefficients of the two, the flexible base film and thin film electrode of the solar sail are driven to further reconstruct, thereby changing the configuration of the solar sail.

[0074] The connection between the alloy beam 11 and the thin film electrode acts as a flexible hinge.

[0075] Specifically, such as Figure 4 and Figure 6 As shown, when different voltages are applied to the first thin-film electrode 20 and the second thin-film electrode 21, current flows through the alloy beam 11 and the reflective beam 15, generating Joule heat. This causes the alloy beam to contract due to the shape memory effect, while the reflective beam expands due to the heat. Due to the mismatch in thermal expansion coefficients, the solar sail's flexible base film and the first and second thin-film electrodes 20, 21 can be further reconfigured. From a macroscopic perspective, this manifests as an increase in the distance between the alloy beam 11 and the flexible base film 3.

[0076] In response to the requirements of attitude adjustment and orbit control of the solar sail, this embodiment can make the solar sail take on different configurations by controlling the high and low voltages loaded on different thin-film electrodes, thereby adjusting the light pressure received by the solar sail.

[0077] like Figure 7 As shown, a high voltage is applied to the first thin-film electrode 20, while a low voltage is applied to the remaining thin-film electrodes. At this point, the solar sail blades covered by the first and second thin-film electrodes 20 and 21, and the solar sail blades covered by the first and fourth thin-film electrodes 20 and 23, are further reconfigured after passive deployment. However, the other two solar sail blades remain unchanged, thus changing the light pressure on the different blades of the solar sail. This asymmetric light pressure distribution can create a light pressure moment on the solar sail surface, thereby enabling the solar sail's attitude adjustment.

[0078] like Figure 8As shown, a high voltage is applied to the first thin-film electrode 20 and the fourth thin-film electrode 23, while a low voltage is applied to the remaining thin-film electrodes. At this point, the solar sail blades covered by the first and second thin-film electrodes 20 and 21, and the solar sail blades covered by the third and fourth thin-film electrodes 22 and 23, undergo further reconfiguration based on passive deployment, while the other two solar sail blades remain unchanged, thereby changing the light pressure on the different blades of the solar sail. However, this solar sail configuration can only reduce the light pressure on the sail; it cannot generate a light pressure torque, and therefore can only be used for solar sail orbit control.

[0079] like Figure 9 As shown, a high voltage is applied to the first thin-film electrode 20 and the second thin-film electrode 21, and a low voltage is applied to the other thin-film electrodes. Then, the four blades of the solar sail are reconstructed simultaneously under the drive of the shape memory effect. This configuration also cannot generate a light pressure moment, but it can more significantly regulate the light pressure on the solar sail and its flight orbit, thereby achieving efficient orbit control.

[0080] Therefore, in the solar sail of this embodiment, the four thin-film electrodes can be independently loaded with voltage, thereby realizing the regulation of the solar sail configuration. Loading voltage to different thin-film electrodes can produce different configurations, which can be used for attitude adjustment and orbit adjustment.

[0081] The above description is merely a preferred embodiment of the present application and is not intended to limit the present application. Various modifications and variations are possible for those skilled in the art. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present application shall be included within the scope of protection of the present application.

Claims

1. A method for processing a spacecraft solar sail, characterized in that: The following steps are involved: Spin coating a bottom layer on a silicon wafer, and then spin coating a flexible base film on the bottom layer; forming a first deposition area on the flexible base film using a photolithography process, and depositing a thin film electrode in the first deposition area; A second deposition area is formed on the overall structure after thin film electrode deposition using a photolithography process, and then an alloy beam is deposited in the second deposition area, wherein the alloy beam is deposited between two adjacent thin film electrodes; forming a third deposition area on the alloy beam using a photolithography process, and depositing a reflective beam in the third deposition area; Removing the photoresist and sacrificial layer remaining between the alloy beam and the flexible base film and the thin film electrode due to the photolithography process, and peeling the flexible base film from the bottom layer to generate residual stress in the flexible base film; The flexible base film after peeling has residual stress inside. This residual stress causes the flexible base film and thin film electrode of the solar sail to bend downward, and the double-layer beam structure formed by the alloy beam and the reflective beam to bend upward. The residual stress induces the solar sail to unfold along the thickness direction.

2. A method for processing a spacecraft solar sail according to claim 1, characterized in that: The flexible base film is a polyimide film.

3. A method for processing a spacecraft solar sail according to claim 1, characterized in that: The film electrode is made of a metal material that expands when heated.

4. A method for processing a spacecraft solar sail according to claim 3, characterized in that: The heat-expanding metal material is aluminum.

5. The method for processing a spacecraft solar sail according to claim 1, wherein: Spin-coating photoresist on the flexible base film, performing photolithography, exposing and developing to form a first deposition area, and removing the exposed photoresist outside the first deposition area after the thin film electrode deposition is completed.

6. The method for processing a spacecraft solar sail according to claim 1, wherein: The alloy beam is made of a metal material that shrinks when heated.

7. A method for processing a spacecraft solar sail according to claim 6, characterized in that: The heat-shrinkable metal material is nickel-titanium shape memory alloy.

8. The method for processing a spacecraft solar sail according to claim 1, wherein: A sacrificial layer and a photoresist are sequentially sputtered on the overall structure formed after depositing the flexible base film, and photolithography is performed. After exposure and development, a remaining sacrificial layer and photoresist are formed. Then, the photoresist is spin-coated again and photolithography is performed. After exposure and development, a second deposition area is formed, and an alloy beam is deposited in the second deposition area.

9. The method for processing a spacecraft solar sail according to claim 1, wherein: The reflective beam is made of a metal material that expands when heated.

10. A method for processing a spacecraft solar sail according to claim 9, characterized in that: The heat-expanding metal material is aluminum.

11. The method for processing a spacecraft solar sail according to claim 1, wherein: After removing the excess parts in the alloy beam and the excess exposed photoresist generated during the photolithography of the second deposition area, photoresist is spin-coated on the formed overall structure and photolithography is performed. After exposure and development, a third deposition area is formed on the upper surface of the alloy beam, and a reflective beam is deposited in the third deposition area.

12. A solar sail, characterized in that: The solar sail is manufactured by the solar sail processing method according to any one of claims 1 to 11.

13. A solar sail according to claim 12, characterized in that: The flexible base film of the solar sail adopts a cross-shaped structure. Accordingly, the thin film electrodes are L-shaped and are provided in four configurations. The corners of the four thin film electrodes are arranged facing each other so that the four thin film electrodes are distributed in a cross-shaped manner on the flexible base film. A cross-shaped gap is formed between the four thin film electrodes and is concentric with the flexible base film. A plurality of alloy beams are provided between the opposing portions of two adjacent thin film electrodes. The flexible base film after peeling has residual stress inside. This residual stress causes the flexible base film and thin film electrode of the solar sail to bend downward, and the double-layer beam structure formed by the alloy beam and the reflective beam to bend upward. The residual stress induces the solar sail to unfold along the thickness direction.

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