Production of spacecraft structures in the space vacuum environment by extrusion

Abstract

A method for producing a spacecraft structure includes launching from Earth into a space environment a partially manufactured form of a spacecraft structure, and extruding the partially manufactured form into an extruded spacecraft structure, the extruding taking place in a zero gravity condition in the space environment.

Description

PRODUCTION OF SPACECRAFT STRUCTURES IN THE SPACE VACUUM ENVIRONMENT BY EXTRUSIONFIELD OF THE INVENTION

[0001] The invention relates to an apparatus and a process for the production of spacecraft structures, such as polymer-based structures, in the space vacuum environment via extrusion.BACKGROUND OF THE INVENTION

[0002] Spacecraft are limited by the mass and volume constraints of the launch vehicle. Another major constraint is the volume packing ratio of a stowed to deployed spacecraft. A launch process may take only a few minutes, a tiny fraction of time compared to the years of service in space. However, due to the harsh launch conditions, space structures far more massive and heavier than actually needed after launch are built, and immense resources are invested in their design and testing in order to withstand the launch conditions.SUMMARY

[0003] The present invention seeks to replace prior art spacecraft production methods, which are based on complete on-Earth production, by a novel solution which involves launching partially manufactured spacecraft substructures and completing their manufacturing during orbit directly in the space vacuum environment by extrusion of polymer-based or nanocomposite-based structures in zero gravity conditions. The process relies on space-qualified extrudable polymer-based or nanocomposites durable in the space environment.

[0004] In one non-limiting method of the invention, the process includes launching liquid-state polymer or nanocomposite precursors into space orbit, mixing, extruding, and curing them under zero gravity space conditions until a solid and rigid structure is formed. The process relies on space-qualified materials. Thus, only after complete curing has been achieved does the extruded structure exit the extrusion apparatus and become exposed to the space environment without the risk of contaminating the spacecraft. Since the extrusion process is performed in zero gravity conditions, the extruded structures are extremely accurate and uniform in terms of their final dimensions.

[0005] By launching liquid-state precursors into orbit, the best volume-packing ratio is obtained, and the extruded structure dimensions are limited only by the volume of the launched precursors. Thus, extremely long and massive structures can be directly produced in space.

[0006] In the case that a uniform flow velocity profile within the extrusion apparatus is designed, linear, so-called ID hollow structures will be extruded. In the case of a non- uniform flow velocity profile, non-linear, so-called 2 or 3D hollow structures will be extruded. If the non-uniform flow velocity profile is constant, closed circular structures, such as parabolic surfaces or planar discs, may be produced. If the non-uniform flow velocity profile is attenuating, more complex structures can be extruded.

[0007] The electrical conductivity properties of the extruded structure can be controlled in several ways. In one non-limiting example, the nanocomposite materials are compounded with conductive fillers. In another non-limiting example, the natural vacuum environment in space is exploited by following the extrusion process with a sputtering or thermal coating process of a metal thin film on the surface of the extruded structure.

[0008] There is provided in accordance with a non-limiting embodiment of the invention a method for producing a spacecraft structure including launching from Earth into a space environment a partially manufactured form of a spacecraft structure, and extruding the partially manufactured form into an extruded spacecraft structure, the extruding taking place in a zero gravity condition in the space environment.

[0009] In accordance with a non-limiting embodiment of the invention the extruding takes place during orbit movement in the space environment. Alternatively, in accordance with another non-limiting embodiment of the invention, the extruding takes place before or after achieving orbit movement in the space environment.

[0010] In accordance with a non-limiting embodiment of the invention the partially manufactured form includes a polymer-based or nanocomposite-based structure.

[0011] In accordance with a non-limiting embodiment of the invention the partially manufactured form includes a liquid-state polymeric or nanocomposite precursor which is launched into the space environment, and the liquid-state polymeric or nanocomposite precursor is mixed, extruded, and cured in the zero gravity condition until a solid and rigid structure is formed which is the extruded spacecraft structure.

[0012] In accordance with a non-limiting embodiment of the invention the extruded spacecraft structure exits an extrusion apparatus only after the extruded polymer or nanocomposite from which the spacecraft structure is made of has been completely cured.

[0013] In accordance with a non-limiting embodiment of the invention during the extruding, material of the partially manufactured form flows with a uniform (or alternatively, non-uniform) flow velocity profile within an extrusion apparatus.BRIEF DESCRIPTION OF DRAWINGS

[0014] The present invention will be understood and appreciated more fully from the following detailed description, taken in conjunction with the drawings in which:

[0015] Fig. 1 is a simplified illustration of space-born extrusion apparatus, in accordance with a non-limiting embodiment of the invention.

[0016] Fig. 2 is a simplified illustration of an extrusion process for a uniform flow velocity profile that allows the extrusion of linear structures, in accordance with a nonlimiting embodiment of the invention.

[0017] Fig. 3 is a simplified illustration of an extrusion process for a non-uniform flow velocity profile that yields extrusion of non-linear structures, in accordance with a nonlimiting embodiment of the invention.DETAILED DESCRIPTION

[0018] Reference is now made to Fig. 1, which illustrates a space-born extrusion apparatus, in accordance with a non-limiting embodiment of the invention. The polymeric or nanocomposite precursors may be stored in syringe-like storing compartments and fed using a pump into a static mixer. From the static mixer, the mixed precursors may flow via tubing to a plug-flow reactor (PFR), where the mixed resin and hardener may be continually pushed forward while under curing. The extruded structure may exit the PFR, so that it is exposed to the space environment only when it is fully cured. A sputtering or thermal evaporation unit may be integrated with the apparatus to allow a metallic conductive coating to be applied on the surface of the extruded structure.

[0019] The thermoset polymeric matrix for the extrusion process may be either thermally or UV-cured (or otherwise cured). In the case of a two-component, thermally cured thermoset, the PFR may be integrated with a heating source to achieve complete curing.In the case of the UV-based curing mechanism, the heating source may be replaced by a UV source, and the PFR may be UV transparent.

[0020] The precursors for the extrusion process may be launched in liquid form. However, only a perfectly cured resin is preferably exposed to the vacuum environment. In the case of partial curing of the polymer or nanocomposite, uncured molecular fragments may outgas and contaminate critical surfaces of a spacecraft. The curing mechanism of the present invention enables developing an extrusion process in which a liquid resin is fed to the PFR on one side and a solid, space-qualified polymer or nanocomposite exits the PFR on the other side.

[0021] Space materials are covered, painted, or coated with various silicone- or oxidebased layers to protect them from the space environment. After its extrusion, the extruded polymer or nanocomposite directly faces the space environment; it thus needs desirable properties to withstand the space environment and maintain a rigid structure. Such properties include low outgassing, atomic oxygen and UV durability, and correct thermo- optical properties to prevent overheating.

[0022] Fig. 2 presents an extrusion process designed for a uniform flow velocity profile that allows the extrusion of linear structures. The uniform flow velocity profile within the extruder allows the yet-liquid-form mixed precursors to propagate along the PFR at a uniform velocity until reaching a fully cured solidified state. As the process continues, the fully cured polymer-based or nanocomposite-based structure exits the PFR and is exposed to the space environment. Since the process takes place in zero gravity conditions, no gravitational forces operate, and the extruded structure continues to propagate in a linear motion. Thus, extremely long linear structures may be produced in orbit.

[0023] Fig. 3 presents a schematic description of an extrusion process designed for a non- uniform flow velocity profile that yields extrusion of non-linear structures. Such nonlinear structures may be circular, either planar or contoured; however, they can have more complex shapes, such as a helix, if a more complex flow velocity profile is introduced into the extruder.

Claims

CLAIMSWhat is claimed is:

1. A method for producing a spacecraft structure comprising: launching from Earth into a space environment a partially manufactured form of a spacecraft structure; and extruding said partially manufactured form into an extruded spacecraft structure, said extruding taking place in a zero gravity condition in the space environment.

2. The method according to claim 1, wherein said extruding takes place during orbit movement in the space environment.

3. The method according to claim 1, wherein said extruding takes place before or after achieving orbit movement in the space environment.

4. The method according to claim 1 , wherein said partially manufactured form comprises a polymer-based or nanocomposite-based structure.

5. The method according to claim 1, wherein said partially manufactured form comprises a liquid-state polymer or nanocomposite precursor which is launched into the space environment, and said liquid-state polymer or nanocomposite precursor is mixed, extruded, and cured in the zero gravity condition until a solid and rigid structure is formed which is said extruded spacecraft structure.

6. The method according to claim 1, wherein said extruded spacecraft structure exits an extrusion apparatus only after said extruded spacecraft structure has been completely cured.

7. The method according to claim 1, wherein during said extruding, material of said partially manufactured form flows with a uniform flow velocity profile within an extrusion apparatus.

8. The method according to claim 1, wherein during said extruding, material of said partially manufactured form flows with a non-uniform flow velocity profile within an extrusion apparatus.

9. The method according to claim 8, wherein said non-uniform flow velocity profile is constant.

10. The method according to claim 8, wherein said non-uniform flow velocity profile is attenuating.

11. The method according to claim 1, wherein said partially manufactured form comprises electrically conductive fillers.

12. The method according to claim 1, further comprising sputtering or thermal coating an electrically conductive film or coating on a surface of said extruded spacecraft structure.

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