DE102021108420A1 - Spacecraft membrane, spacecraft photovoltaic module, resistive sail, membrane antenna, solar sail and using a spacecraft membrane - Google Patents

Abstract

The invention relates to a spacecraft membrane (2) which is self-supporting and flexible. The spacecraft membrane (2) has a substrate (5) made of a fluoropolymer. Furthermore, the spacecraft membrane (2) has a silicon oxide layer (6; 7). The silicon oxide layer (6; 7) protects the substrate (5) from the effects of atomic oxygen in low earth orbit or a reflective solar sail.

Description

TECHNICAL FIELD OF THE INVENTION

The present invention relates to a self-supporting flexible spacecraft membrane. Furthermore, the invention relates to different applications of a spacecraft membrane.

STATE OF THE ART

• http://www.sheldahl.com/sites/default/files/Documents/ShieldingMaterials/RedBook.pdf

werden einerseits Klebebänder angeboten, die bereits eine Beschichtung aus einem Acryl-Klebstoff aufweisen und eine Breite im Bereich von 1 bis 4 Inch aufweisen und zu einer Rolle aufgerollt sein können. Ein erstes derartiges Klebeband weist zusätzlich zu der Klebstoffschicht eine ITO-Schicht, eine Trägerfolie aus FEP und eine Schicht aus Silber oder Inconel (eingetragene Marke des Unternehmens Special Metals Corporation) auf, wobei die Dicke der Schichten sehr viel kleiner ist als die Dicke der TrägerfolieOn the website:

• http://www.sheldahl.com/sites/default/files/Documents/ShieldingMaterials/RedBook.pdf

On the one hand, adhesive tapes are offered which already have a coating of an acrylic adhesive and have a width in the range from 1 to 4 inches and can be rolled up into a roll. A first such adhesive tape has, in addition to the adhesive layer, an ITO layer, an FEP carrier film and a silver or Inconel (registered trademark of Special Metals Corporation) layer, the thickness of the layers being much smaller than the thickness of the carrier film

This tape is intended for sticking to a structure to affect heat transfer. The tape can be applied to blankets to seal edges or repair ribs in the outer layers. The adhesive tape can also have perforations. Another adhesive tape has, in addition to the adhesive layer, only an FEP layer and a reflective layer made of silver or Inconel. This adhesive tape is also stuck onto a structure to influence the heat transfer and can be perforated. The adhesive tape can have a protective layer that can be removed after application in order to protect the adhesive tape from damage during use and application. The reflection behavior can be made diffuse by embossing the reflective layer. Alternatively, an aluminum layer can also be used instead of the silver or Inconel layer. The website also proposes adhesive tapes in which an ITO layer is arranged on one side of a FEP layer, while a layer of silver or Inconel is arranged on the other side of the FEP layer, which in turn is coated with the adhesive layer.

On the other hand, the website also discloses large-area pieces of film, which can have a length of 3 m and a width of 1.22 m, for example. In such a piece of foil, one side of an FEP layer is coated with an ITO layer, while the other side of the FEP layer is coated with a silver layer or a layer of Inconel. Such pieces of film can also be perforated. If a piece of film is to be used as a so-called rear surface mirror, in that reflection does not take place on the side of the piece of film directly facing the radiation source, but on a second reflection surface of a film layer located within the piece of film, an FEP layer on the side facing away from the radiation source can be used be coated with a layer of silver or a layer of Inconel. This results in a low solar absorption capacity and a high emissivity. This piece of film can also be perforated and equipped with a protective layer. Alternatively (given an otherwise appropriate configuration), the reflection layer that is bonded to the FEP layer can be an aluminum layer.

DE 10 2007 041 410 B4 discloses a sail foil for a solar sail. The sail foil has an external titanium dioxide layer on the front, which is followed by a silicon dioxide layer and an aluminum layer. The three layers mentioned are vapour-deposited onto a carrier foil. The three layers mentioned are preferably vapor-deposited onto both sides of the carrier film. The carrier foil consists of polyimide or another polymer material. It is also possible that the aluminum layer itself forms the carrier foil. The selected layer structure is intended to increase the reflectivity of the sail foil, which increases the propulsion effect through the radiation pressure of the sun. Furthermore, the titanium dioxide layer should make the outer surface of the sail foil particularly resistant to degradation of the thermo-optical properties and increase its suitability for space travel. The titanium oxide layer also acts as an antistatic coating.

OBJECT OF THE INVENTION

• - der Verarbeitung und/oder
• - der Widerstandsfähigkeit (bspw. gegen die Weltraumumgebung und in dieser vorhandenen atomaren Sauerstoff) und/oder
• - der thermo-optischen Eigenschaften und/oder
• - des Schutzes des Substrats vor UV-Strahlung und/oder
• - der Dauerbeständigkeit (bspw. gegen atomaren Sauerstoff) und/oder
• - des Reflektionsverhaltens und/oder
• - des Schutzes gegenüber kurzwelliger UV-Strahlung und/oder
• - der lokalen elektrischen Isolation von elektrischen Komponenten und/oder
• - der Vermeidung einer elektrostatischen Aufladung und/oder
• - der Anhaftung eines Klebstoffes und/oder
• - des Herstellungsaufwandes und/oder
• - der Verstärkung eines Randes oder einer Kante und/oder
• - der Verbindung unterschiedlicher Folienstücke miteinander und/oder
• - des Schichtaufbaus der Raumfahrzeugmembran und der Übernahme unterschiedlicher Funktionen durch die einzelnen Schichten und/oder
• - der verbesserten Verklebbarkeit durch Erhöhung der Adhäsion und/oder
• - der Aufbringung von Rissstoppern und/oder
• - der Aufbringen elektrischer Komponenten (Photovoltaik, Harness, Dioden usw.).
• - der Verwendung als Sandwichmaterial im Verbund mit anderen Folien

verbessert ist. Des Weiteren ist es Aufgabe der Erfindung, neue Anwendungsgebiete einer entsprechend verbesserten Raumfahrzeugmembran vorzuschlagen.The invention has for its object to propose a spacecraft membrane, in particular with regard to

• - the processing and/or
• - the resistance (e.g. to the space environment and the atomic oxygen present in it) and/or
• - the thermo-optical properties and/or
• - the protection of the substrate from UV radiation and/or
• - the durability (e.g. against atomic oxygen) and/or
• - the reflection behavior and/or
• - protection against short-wave UV radiation and/or
• - the local electrical insulation of electrical components and/or
• - the avoidance of electrostatic charging and/or
• - the adhesion of an adhesive and/or
• - the production costs and/or
• - the reinforcement of an edge or an edge and/or
• - the connection of different pieces of film to one another and/or
• - The layer structure of the spacecraft membrane and the assumption of different functions by the individual layers and / or
• - The improved bondability by increasing the adhesion and/or
• - the application of crack stoppers and/or
• - the application of electrical components (photovoltaic, harness, diodes, etc.).
• - Use as a sandwich material in combination with other foils

is improved. Furthermore, it is the object of the invention to propose new areas of application for a correspondingly improved spacecraft membrane.

SOLUTION

The object of the invention is achieved according to the invention with the features of the independent patent claims. Further preferred configurations according to the invention can be found in the dependent patent claims.

DESCRIPTION OF THE INVENTION

The invention relates to a spacecraft membrane intended for and sent on a mission with a satellite or other spacecraft. The spacecraft membrane is self-supporting and flexible. Self-supporting here means that the spacecraft membrane is not glued to a rigid structure of the spacecraft in accordance with the adhesive tape mentioned at the beginning, but is stretched, unpacked, unfolded, unrolled at least in one operating state and is only connected to adjacent components in partial areas, edges or corners and is connected to this is held. Here, the spacecraft membrane is flexible, so that it can assume different geometries, in particular a packed state and an unpacked state. To name just a few examples that do not limit the invention, the spacecraft membrane according to the invention can be part of a solar sail, carry at least one solar cell, be designed as a resistance sail or be designed as a membrane antenna.

Conventional spacecraft diaphragms have a substrate made of a plastic such as polyimide. However, one finding on which the invention is based is that conventional substrates of spacecraft membranes are severely attacked by atomic oxygen, such as is present in low earth orbits, which shortens the life of the spacecraft membrane or requires additional measures to protect the substrate.

According to the invention, a substrate made of a “fluorinated plastic” is used for the first time for the self-supporting, flexible spacecraft membrane. Investigations on which the invention is based have shown that the substrate made of the fluorinated plastic has a higher resistance to exposure to atomic oxygen. However, even if one skilled in the art would have recognized that the use of a fluorinated plastic substrate is advantageous for this reason, the use of such a substrate for the present spacecraft membrane would not have been considered. The reason for this is that, when trying to use a substrate made of a fluorinated plastic, the person skilled in the art would have found that the substrate had to be bonded to adjacent layers or components (such as is required, for example, to ensure additional functions, for edge reinforcement). or for connecting several foil webs or for applying electrical components, e.g. photovoltaics) is not easily possible. Rather, the technical challenge of bonding a fluoroplastic substrate to another layer or component has only been solved to a limited extent. Approaches here are chemical etching processes or plasma treatments in order to roughen the surface of the substrate made of the fluoroplastic and to enable adhesion of the adhesive. However, these methods, which are additionally required for the bonding, are complicated, increase the costs and are only partially successful.

On the other hand, it is possible that the use of a substrate made of fluorinated plastic ensures increased resistance to short-wave UV radiation (especially vacuum ultraviolet radiation).

According to the invention, it is proposed for the first time that the spacecraft membrane has at least one silicon oxide layer, which is preferably directly attached to the sub on one or both sides strat of a fluorinated plastic is attached. The silicon oxide layer can have any thickness, for example a thickness of 10 nm to 100 nm. On the one hand, the silicon oxide layer can serve to increase the resistance of the substrate to atomic oxygen. It is alternatively or cumulatively possible for the silicon oxide layer to ensure protection of the substrate and the spacecraft membrane with regard to short-wave UV radiation. It is also alternatively or cumulatively possible for the silicon oxide layer to provide a type of adhesion promoter for further layers, components or an adhesive or a type of adhesive interface. The silicon oxide layer can be firmly bonded to the substrate made of the fluorinated plastic. The outside of the silicon oxide layer facing away from the substrate can then be used to attach or bond further layers or components.

• a) Der fluorierte Kunststoff kann ein Florpolymer-Polymer auf Basis von Fluorcarbonen mit mehrfachen Kohlenstoff-Fluor-Bindungen sein. Dabei kann ein Großteil des Wasserstoffs mit Fluor ersetzt sein, was zu einer hohen chemischen und thermischen Stabilität führt. Man kann dann auch von einer Fluorierung oder einem fluorierten Kunststoff sprechen, bei dem allerdings nicht sämtliche organischen Verbindungen durch Flor ersetzt werden müssen.
• b) Der fluorierte Kunststoff kann ein Thermoplast oder kein Thermoplast sein.
• c) Möglich ist, dass der fluorierte Kunststoff PTFE (Polytetrafluorethylen) ist, womit eine sehr hohe chemische und thermische Stabilität gewährleistet werden kann.
• d) Möglich ist, dass ein FEP (Tetrafluorethylen-Hexafluorpropylen-Copolymer) Einsatz findet.
• e) Als Weiterentwicklung eines PTFE kann beispielsweise auch ein vollständig fluorierter Kunststoff Einsatz finden.
• f) Möglich ist der Einsatz eines PFA (Perfluoralkoxy-Polymer).
• g) Möglich ist der Einsatz eines Gemisches aus verschiedenen Flormonomeren.
• h) Eingesetzt werden kann ein Mix aus Florpolymeren, insbesondere THV (Terpolymer aus Tetrafluorethylene, Hexafluoropropylene und Vinylidene Fluoride).
• i) Eingesetzt werden können auch weitere, nicht vollständig fluorierte Kunststoffe wie insbesondere ETFE (Ethyl-Tetrafluorethyl-Copolymer), ECTFE (Ethylen Chlor Tri Fluor Ethylen) oder PVDF (Polyvinylidenfluorid).

The following possibilities exist for the fluorinated plastic from which the substrate is made:

• a) The fluorinated plastic may be a fluorocarbon-based fluorocarbon polymer having multiple carbon-fluorine bonds. A large part of the hydrogen can be replaced with fluorine, which leads to high chemical and thermal stability. One can then also speak of fluorination or a fluorinated plastic, although not all of the organic compounds have to be replaced by flor.
• b) The fluorinated plastic can be a thermoplastic or non-thermoplastic.
• c) It is possible that the fluorinated plastic is PTFE (polytetrafluoroethylene), which ensures very high chemical and thermal stability.
• d) It is possible that an FEP (tetrafluoroethylene-hexafluoropropylene copolymer) is used.
• e) As a further development of a PTFE, a fully fluorinated plastic can also be used, for example.
• f) It is possible to use a PFA (perfluoroalkoxy polymer).
• g) It is possible to use a mixture of different fluoromonomers.
• h) A mix of pile polymers can be used, in particular THV (terpolymer of tetrafluoroethylene, hexafluoropropylene and vinylidene fluoride).
• i) Other plastics that are not completely fluorinated can also be used, such as in particular ETFE (ethyl tetrafluoroethyl copolymer), ECTFE (ethylene chlorine trifluorine ethylene) or PVDF (polyvinylidene fluoride).

If the focus is on resistance to atomic oxygen and use at high temperatures, pure pile polymers are advantageous in some cases. In this case, the properties can be adjusted by mixing or layering with other plastics. Here, in particular, there is an adjustment to improve the mechanical properties, to lower the melting point and/or to influence the viscosity for industrial processing.

Preferably the fluorinated plastic is transparent so that it is completely transparent or at least translucent. The spacecraft membrane formed with the substrate can then be transparent or non-transparent, so that the additional layers are then transparent or non-transparent.

The invention includes embodiments in which the spacecraft diaphragm consists solely of the fluorinated plastic substrate and a silicon oxide layer on at least one side of the substrate. However, it is also possible for at least one further layer to be arranged between the substrate and the silicon oxide layer and/or for at least one further layer to be arranged on the side of the silicon oxide layer facing away from the substrate. For one proposal of the invention, the substrate is coated on at least one side with an ITO layer and/or a titanium oxide layer. In this context, ITO refers to an indium tin oxide, i.e. a semi-conductive material that is largely transparent in visible light. Such a layer can have any thickness, for example in the range from 10 nm to 100 nm. Such a layer can serve as an antistatic coating. Alternatively or cumulatively, such a layer can also serve as an adhesive interface. For one proposal of the invention, a silicon oxide layer can be arranged directly between the substrate on the one hand and the ITO layer or the titanium oxide layer on the other.

If the spacecraft membrane according to the invention is intended to reflect radiation, the substrate can be coated on at least one side with an aluminum and/or silver layer. Here, the aluminum or silver layer can form an outer side of the spacecraft membrane. However, it is also possible for the aluminum or silver layer to be covered by at least one then transparent layer, so that the radiation initially passes through this covering at least one transparent layer before it is reflected by the aluminum or silver layer.

The aforementioned silicon oxide layer, the ITO layer and/or the titanium oxide layer can be used to form an adhesive interface, as explained. In this case, it may be possible to use a conventional acrylic or silicone adhesive that adheres to the adhesive interface provided. The use of such an acrylic or silicone adhesive would not be readily possible for the direct application of the same to the substrate made of the fluorinated plastic.

The spacecraft membrane can be designed as any planar, for example rectangular, triangular or other shaped track. Preferably, the spacecraft membrane can be placed in a packed state. Here, the spacecraft membrane is preferably rolled and/or folded in the packed state. With regard to the possibilities for packing with superimposed rolling and folding, reference is made, for example, to the reference DE 10 2017 101 178 A1 referred. Also DE 10 2016 101 430 B4 discloses a packed spacecraft membrane with suitable apparatus for unpacking the spacecraft membrane. Packing requires that all layers of the spacecraft membrane be rolled and/or folded, with the rolling or folding not compromising the mechanical integrity of the spacecraft membrane. If rigid elements are held on the spacecraft membrane, such as rigid photovoltaic cells, for example, these can be arranged between folds of the spacecraft membrane in the region of unfolded subregions.

For a further proposal of the invention, the spacecraft membrane has at least one glued-on crack propagation impeding element. In this case, the crack propagation impeding element is designed as a glued-on surface element or glued-on strip or has any other surface extension. The crack propagation impeding element can be glued to the adhesive interface provided by one of the layers mentioned, for example to the ITO layer or the silicon oxide layer. The crack propagation impeding element is preferably arranged in a region of the spacecraft membrane in which the spacecraft membrane is subjected to maximum stress. Strip-shaped crack propagation restraining elements may also run along an outer surface of the spacecraft membrane at regular or irregular intervals or in a grid-like manner. The crack propagation impeding elements can be made from any film material (single-layer, multi-layer), for example any plastic or one of the materials mentioned in the present application.

1. a) Möglich ist, dass die Raumfahrzeugmembran, wie diese zuvor erläutert worden ist, für ein Photovoltaik-Raumfahrtmodul genutzt wird. In diesem Fall ist an die Raumfahrzeugmembran (mindestens) ein Photovoltaik-Element, beispielsweise eine starre oder flexible Photovoltaikzelle oder Photovoltaikmembran, angeklebt. Grundsätzlich kann in diesem Fall eine Raumfahrzeugmembran in beliebiger Ausgestaltung, wie diese oben beschrieben worden sind, eingesetzt werden. Vorzugsweise findet eine Raumfahrzeugmembran Einsatz, bei der ein Querschnitt oder eine Seite der Raumfahrzeugmembran eine Siliziumoxydschicht aufweist, an die das Photovoltaik-Element sowie weitere elektrische Komponenten wie Leiterbahnen (Harness) und Dioden angeklebt sind. Des Weiteren verfügt der Querschnitt der Raumfahrzeugmembran über ein Substrat aus FEP. Hieran schließt eine Siliziumoxydschicht an. Auf der Photovoltaik abgewandten Seite ist ein Beschichtungssystem aus einerseits Siliziumoxyd und andererseits ITO oder Titanoxydschicht vorgesehen. Bei den genannten Schichten kann es sich um sämtliche Schichten handeln oder es können weitere Schichten zwischen den genannten Schichten angeordnet sein oder diese von außen abdecken. Vorzugsweise besteht der Querschnitt der Raumfahrzeugmembran ausschließlich aus den genannten Schichten, wobei diese dann unmittelbar aneinander anschließen in der Reihenfolge, in der diese zuvor genannt worden sind. Eine derartige Raumfahrzeugmembran kann aus einer einzigen Folienbahn bestehen. Möglich ist aber auch, dass die Raumfahrzeugmembran mehrere Folienbahnen aufweist, die jeweils als Raumfahrzeugmembran entsprechend obigen Ausführungen ausgebildet sind. In diesem Fall sind die einzelnen Raumfahrzeugmembrane bzw. Folienbahnen an ihren Rändern miteinander verklebt.
2. b) Möglich ist auch, dass die Raumfahrzeugmembran als Widerstandssegel eingesetzt wird. In diesem Fall weist in Querschnitt der Raumfahrzeugmembran eine Siliziumoxydschicht, ein Substrat aus einem Fluorpolymer oder FEP, eine Siliziumoxydschicht und eine ITO-Schicht oder eine Titanoxydschicht auf einer der Außenseiten einer Siliziumoxydschicht oder jeweils eine ITO-Schicht oder eine Titanoxydschicht auf beiden Außenseiten der Siliziumoxydschichten auf (also Schichtaufbau ITO/Si02/FEP/Si02/ITO oder TiO3/SiO2/FEP/TiO3/SiO2). Bei den genannten Schichten kann es sich um sämtliche Schichten handeln oder es können weitere Schichten zwischen den genannten Schichten angeordnet sein oder diese von außen abdecken. Vorzugsweise besteht der Querschnitt der Raumfahrzeugmembran ausschließlich aus den genannten Schichten, wobei diese dann unmittelbar aneinander anschließen in der Reihenfolge, in der diese zuvor genannt worden sind. Ein derartiges Widerstandssegel kann aus einer einzigen Folienbahn bestehen. Möglich ist aber auch, dass ein Widerstandssegel mehrere Folienbahnen aufweist, die jeweils als Raumfahrzeugmembran entsprechend obigen Ausführungen ausgebildet sind. In diesem Fall sind die einzelnen Raumfahrzeugmembrane bzw. Folienbahnen an ihren Rändern miteinander verklebt. Dabei wirkt die ITO-Schicht und/oder die Titanoxydschicht im Bereich der Überlappungen der Folienbahnen als Klebeinterface zwischen den miteinander verbundenen Folienbahnen. Durch Einsatz eines derartigen Klebeinterfaces kann ein beliebiger Kleber, insbesondere ein herkömmlicher, acrylbasierter oder silikonbasierter Transferkleber, verwendet werden. Für einen weiteren Vorschlag der Erfindung wird alternativ oder kumulativ vorgeschlagen, dass das Widerstandssegel eine Folienbahn aufweist, die im Bereich eines Randes eine verklebte Verstärkung aufweist. Die verklebte Verstärkung kann beispielsweise zur Erhöhung der mechanischen Festigkeit des Widerstandssegels dienen. Möglich ist auch, dass im Bereich des Randes und der Verstärkung eine Befestigung des Widerstandssegels an einem benachbarten Bauelement erfolgt, so dass die Verstärkung zu einer guten Krafteinleitung und zur Applikation der Halte- und/oder Führungskräfte des Widerstandssegels dienen kann. Erfindungsgemäß bildet die mindestens eine ITO-Schicht oder die Titanoxydschicht ein Klebeinterface für die Verstärkung. Im Bereich des Klebeinterfaces kann dann beispielsweise zur Bildung der Verstärkung ein Umklappen der Folienbahn erfolgen, so dass dann die Verstärkung von der Verdopplung der Dicke gebildet ist. Das Klebeinterface dient dann zum Verkleben der unterschiedlichen umgefalteten Lagen der Folienbahn miteinander. Möglich ist aber auch, dass das Klebeinterface zur Befestigung einer zusätzlichen Verstärkung aus einem anderen Material, einer anderen Folienbahn, einer Versteifung o. ä. dient.
3. c) Ein weiterer Anwendungsfall für die erfindungsgemäße Raumfahrzeugmembran ist eine reflektierende Membranantenne, eine Reflektorantenne oder ein reflektierendes Solarsegel. In diesem Fall kann der Querschnitt der Raumfahrzeugmembran eine Siliziumoxydschicht, ein Substrat aus FEP, eine Siliziumoxydschicht und eine Aluminiumschicht auf einer Außenseite einer Siliziumoxydschicht oder jeweils eine Aluminiumschicht auf den Außenseiten der Siliziumoxydschichten aufweisen. Bei den genannten Schichten kann es sich um sämtliche Schichten handeln oder es können weitere Schichten zwischen den genannten Schichten angeordnet sein oder diese von außen abdecken. Vorzugsweise besteht der Querschnitt der Raumfahrzeugmembran ausschließlich aus den genannten Schichten, wobei diese dann unmittelbar aneinander anschließen in der Reihenfolge, in der diese zuvor genannt worden sind. Alternativ möglich ist, dass in einer reflektierenden Membranantenne oder einem reflektierenden Solarsegel ein Querschnitt der Raumfahrzeugmembran eine Aluminiumschicht, ein Substrat aus FEP, eine Aluminiumschicht und eine Siliziumoxydschicht oder Titanoxydschicht auf einer Außenseite einer Aluminiumschicht oder jeweils eine Siliziumoxydschicht oder Titanoxydschicht auf den Außenseiten der Aluminiumschichten aufweist. Bei den genannten Schichten kann es sich um sämtliche Schichten handeln oder es können weitere Schichten zwischen den genannten Schichten angeordnet sein oder diese von außen abdecken. Vorzugsweise besteht der Querschnitt der Raumfahrzeugmembran ausschließlich aus den genannten Schichten, wobei diese dann unmittelbar aneinander anschließen in der Reihenfolge, in der diese zuvor genannt worden sind.
4. d) Eine weitere Lösung der der Erfindung zugrundeliegenden Aufgabe ist die Verwendung einer Raumfahrzeugmembran, wie diese zuvor beschrieben worden ist, als Trägermembran für Photovoltaik-Elemente, als Widerstandssegel, als Membranantenne oder als Solarsegel.

The spacecraft membrane according to the invention can be used for different purposes:

1. a) It is possible that the spacecraft membrane, as explained above, is used for a photovoltaic space module. In this case, the spacecraft membrane has (at least) one photovoltaic element glued to it, for example a rigid or flexible photovoltaic cell or membrane. Basically, in this case, a spacecraft membrane can be used in any configuration, as has been described above. A spacecraft membrane is preferably used in which a cross-section or side of the spacecraft membrane has a silicon oxide layer to which the photovoltaic element and other electrical components such as conductor tracks (harness) and diodes are bonded. Furthermore, the cross-section of the spacecraft membrane has a substrate made of FEP. This is followed by a silicon oxide layer. On the side facing away from the photovoltaic there is a coating system made of silicon oxide on the one hand and ITO or titanium oxide layer on the other hand. The layers mentioned can be all layers or further layers can be arranged between the layers mentioned or cover them from the outside. The cross-section of the spacecraft membrane preferably consists exclusively of the layers mentioned, these then adjoining one another directly in the order in which they have been mentioned above. Such a spacecraft membrane can consist of a single sheet of foil. However, it is also possible for the spacecraft membrane to have a plurality of film webs, each of which is designed as a spacecraft membrane in accordance with the above statements. In this case, the individual spacecraft membranes or foil webs are glued together at their edges.
2. b) It is also possible that the spacecraft membrane is used as a drag sail. In this case, in cross-section, the spacecraft membrane has a silicon oxide layer, a substrate made of a fluoropolymer or FEP, a silicon oxide layer and an ITO layer or a titanium oxide layer on one of the outer sides of a silicon oxide layer, or an ITO layer or a titanium oxide layer on both outer sides of the silicon oxide layers (i.e. layer structure ITO/Si02/FEP/Si02/ITO or TiO3/SiO2/FEP/TiO3/SiO2). The layers mentioned can be all layers act or further layers can be arranged between the layers mentioned or cover them from the outside. The cross-section of the spacecraft membrane preferably consists exclusively of the layers mentioned, these then adjoining one another directly in the order in which they have been mentioned above. Such a resistance sail can consist of a single sheet of film. However, it is also possible for a resistance sail to have a plurality of foil webs, each of which is designed as a spacecraft membrane in accordance with the above statements. In this case, the individual spacecraft membranes or foil webs are glued together at their edges. In this case, the ITO layer and/or the titanium oxide layer acts as an adhesive interface between the foil webs connected to one another in the region of the overlapping of the foil webs. By using such an adhesive interface, any adhesive, in particular a conventional, acrylic-based or silicone-based transfer adhesive, can be used. For a further proposal of the invention, it is alternatively or cumulatively proposed that the resistance sail has a foil web which has a bonded reinforcement in the area of an edge. The bonded reinforcement can be used, for example, to increase the mechanical strength of the resistance sail. It is also possible for the resistance sail to be fastened to an adjacent component in the area of the edge and the reinforcement, so that the reinforcement can be used for good force introduction and for the application of the holding and/or guides of the resistance sail. According to the invention, the at least one ITO layer or the titanium oxide layer forms an adhesive interface for the reinforcement. In the area of the adhesive interface, the film web can then be folded over, for example to form the reinforcement, so that the reinforcement is then formed by the doubling of the thickness. The adhesive interface then serves to bond the different folded layers of the film web to one another. However, it is also possible for the adhesive interface to be used to attach an additional reinforcement made of a different material, a different film web, a stiffener or the like.
3. c) Another application for the spacecraft membrane according to the invention is a reflective membrane antenna, a reflector antenna or a reflective solar sail. In this case, the cross section of the spacecraft membrane may have a silicon oxide layer, a substrate of FEP, a silicon oxide layer and an aluminum layer on an outside of a silicon oxide layer, or an aluminum layer on the outside of the silicon oxide layers, respectively. The layers mentioned can be all layers or further layers can be arranged between the layers mentioned or cover them from the outside. The cross-section of the spacecraft membrane preferably consists exclusively of the layers mentioned, these then adjoining one another directly in the order in which they have been mentioned above. Alternatively, it is possible that in a reflective membrane antenna or a reflective solar sail, a cross-section of the spacecraft membrane has an aluminum layer, a substrate made of FEP, an aluminum layer and a silicon oxide layer or titanium oxide layer on an outer side of an aluminum layer, or a silicon oxide layer or titanium oxide layer on the outer sides of the aluminum layers. The layers mentioned can be all layers or further layers can be arranged between the layers mentioned or cover them from the outside. The cross-section of the spacecraft membrane preferably consists exclusively of the layers mentioned, these then adjoining one another directly in the order in which they have been mentioned above.
4. d) A further solution to the problem on which the invention is based is the use of a spacecraft membrane, as has been described above, as a support membrane for photovoltaic elements, as a resistance sail, as a membrane antenna or as a solar sail.

Advantageous developments of the invention result from the patent claims, the description and the drawings.

The advantages of features and combinations of several features mentioned in the description are merely exemplary and can have an effect alternatively or cumulatively without the advantages necessarily having to be achieved by embodiments according to the invention.

The following applies to the disclosure content - not the scope of protection - of the original application documents and the patent: Further features can be found in the drawings - in particular the illustrated geometries and the relative dimensions of several components to one another as well as their relative arrangement and operative connection. The combination of features of different embodiments of the invention or features of different patent claims is also possible deviating from the selected references of the patent claims and is hereby suggested. This also applies to those features that are shown in separate drawings or are mentioned in their description. These features can also be combined with features of different patent claims. Likewise, features listed in the patent claims can be omitted for further embodiments of the invention, but this does not apply to the independent patent claims of the granted patent.

The features mentioned in the patent claims and the description are to be understood with regard to their number in such a way that exactly this number or a larger number than the number mentioned is present without the need for an explicit use of the adverb “at least”. So if, for example, an element is mentioned, this is to be understood in such a way that exactly one element, two elements or more elements are present. These characteristics may be complemented by other characteristics or they may be the only characteristics that make up the product in question.

The reference signs contained in the claims do not limit the scope of the subject-matter protected by the claims. They only serve the purpose of making the claims easier to understand.

character list

• 1 zeigt stark schematisiert einen Aufbau oder Querschnitt einer Raumfahrzeugmembran, bei der es sich vorzugsweise um ein Photovoltaik-Raumfahrtmodul handelt.
• 2 zeigt stark schematisiert einen Aufbau oder Querschnitt einer Raumfahrzeugmembran, bei der es sich vorzugsweise um ein Widerstandssegel handelt.
• 3 zeigt stark schematisiert einen Aufbau oder Querschnitt einer Raumfahrzeugmembran für eine erste Ausführungsform eines Reflektors für eine Membranantenne oder ein Solarsegel.
• 4 zeigt stark schematisiert einen Aufbau oder Querschnitt einer Raumfahrzeugmembran für eine zweite Ausführungsform eines Reflektors für eine Membranantenne oder ein Solarsegel.

The invention is further explained and described below with reference to preferred exemplary embodiments illustrated in the figures.

• 1 shows a highly schematic structure or cross section of a spacecraft membrane, which is preferably a photovoltaic space module.
• 2 shows a highly schematic structure or cross-section of a spacecraft membrane, which is preferably a drag sail.
• 3 shows a highly schematic structure or cross section of a spacecraft membrane for a first embodiment of a reflector for a membrane antenna or a solar sail.
• 4 shows a highly schematic structure or cross section of a spacecraft membrane for a second embodiment of a reflector for a membrane antenna or a solar sail.

FIGURE DESCRIPTION

1 shows a highly schematized layered structure of a photovoltaic space module 1 with a spacecraft membrane 2. The photovoltaic space module 1 has a photovoltaic element 3, which can be a photovoltaic cell and can be rigid or designed as a flexible photovoltaic membrane and possibly other for the function can have important components such as electrical contact (harness) and/or diodes.

A plurality of such photovoltaic elements 3 are preferably distributed over the spacecraft membrane 2 in a regular or irregular manner. The photovoltaic element 3 is bonded to the spacecraft membrane 2 via an adhesive layer 4, preferably made of an acrylic or silicone adhesive.

The spacecraft membrane 2 has a substrate 5, which can also be designed as a carrier layer. The substrate 5 consists of fluorinated plastic, with all the fluorinated plastics listed above being able to be used. On both sides of the substrate 5, a silicon oxide layer 6, 7 is connected to it. The silicon oxide layer 6, which is arranged on the side of the substrate 5 facing the photovoltaic element 3, forms an adhesive interface 8, which enables or improves the adhesion of the adhesive layer 4. An ITO layer 9 is bonded to the outside of the silicon oxide layer 7 on the side of the substrate 5 facing away from the photovoltaic element 3 . It is possible that the photovoltaic space module 1 is composed of several foil webs 10a, 10b, 10c, . . . which are glued together at their edges. In this case, the ITO layer 9 can serve as an adhesive interface 11 in order to enable the overlapping edges to be adhesively bonded. The silicon oxide layer 6, 7 can provide UV protection, while the ITO layer 9 can provide an antistatic coating. It is possible that a titanium oxide layer is used instead of the ITO layer 9 .

2 shows schematically the layered structure of a resistance sail 12. Here, a silicon oxide layer 6, 7 is bonded on both sides to the substrate 5, in particular made of FEP or fluoropolymer. This is followed by an ITO layer 9, 13 in each case. Here, too, several foil webs 10a, 10b, 10c, ... can be connected to one another. In this case, the outsides of the ITO layers 9, 13 can form an adhesive interface 11 in the area of the overlaps. It is also possible for the foil webs 10 to be reinforced in the area of their edges or an edge. This reinforcement can consist of a folding over of the edge, in which case the folded film areas are then glued together will. In this case, the folded, mutually facing outer sides of the ITO layer 9 or the ITO layer 13 can each form an adhesive interface, which enables the adhesive bond. However, it is also possible for the edge to be glued to a separate reinforcement. It is possible that a titanium oxide layer is used instead of the ITO layer 9.13.

3 shows the use of the spacecraft membrane 2 for a membrane antenna 14 or a reflector of the same or a solar sail 15. For the in 3 The exemplary embodiment illustrated adjoins the substrate 5, which preferably consists of an FEP film or fluoropolymer film, in each case with a silicon oxide layer 6, 7. The silicon oxide layers 6, 7 are coated with an aluminum layer 16, 17 on their outside. Here, the aluminum layers 16, 17 ensure the required reflection. On the other hand, UV resistance can be ensured by means of the silicon oxide layers 6, 7, with which long-term stability can be ensured.

4 also shows a membrane antenna 14 or a solar sail 15, in which the thermo-optical properties are adjusted by an oxide coating on the outside. Here the aluminum layers 16, 17 directly adjoin the substrate 5, in particular made of FEP or fluoropolymer. The aluminum layers 16, 17 are coated on the outside by silicon oxide layers 6, 7, respectively. Alternatively, the aluminum layers 16, 17 can be coated with a titanium oxide layer 18, 19 on their outsides. The outer oxide layer 6, 7 or 18, 19 can improve the radiation behavior in the infrared range. At the same time, good reflection behavior can be ensured by means of the aluminum layer 16, 17 lying on the inside.

For the exemplary embodiments shown, the substrate made of the fluorinated plastic was constructed in one layer. However, it is also quite possible for the substrate 5 to consist of a plurality of laminated layers, which consist of the same or different materials or fluorinated plastics. The individual layers then preferably serve to provide different desired properties.

The exemplary embodiments shown in the drawings can only have the layers shown and named. It is entirely possible for the spacecraft membrane to have additional elements such as stiffening elements, electrical lines, eyelets, deployment safety elements, packaging elements, electrical components, reinforcements, intermediate layers or at least one further outer layer.

A transparent, non-reflective spacecraft membrane using the fluorinated plastic can reduce light pollution in the night sky. The reflections of reflective spacecraft membranes, in particular with an aluminum coating, are clearly visible in the night sky and are a problem, especially in relation to the launch of large constellations with hundreds of satellites, e.g. for astronomy.

The thicknesses of the layers discussed here can be the same or different. Layers with a layer thickness of 10 nm to 100 nm, preferably 20 nm to 80 nm or 30 nm to 70 nm, are preferably used.

The spacecraft membrane 2 is preferably glued to components such as the photovoltaic element, edge reinforcements, adjacent foil webs or other structural elements by means of an adhesive layer 4 made of an acrylic adhesive or silicone adhesive. For example, the substrate 5 can have an inner polyimide film that is intended to ensure the mechanical strength of the substrate 5 . A layer of a fluorinated plastic can then be applied to at least one outside of the polyimide film. This can be vapor-deposited, for example. It is also possible that a thermoplastic fluorinated plastic is used, which is then pressed onto the inner polyimide film at high temperature and forms the required connection.

The invention also includes embodiments with a layer system in which a reflector layer (aluminum or silver) is combined with SiO2 and ITO and this reflector layer is arranged on the substrate 5 made of a fluoropolymer, if necessary with further layers on this or the other side of the substrate 5. Such a spacecraft membrane can then be used, for example, for reflector antennas and solar sails.

A layer structure of aluminum/fluoropolymer/SiO 2 /ITO is also possible, it also being possible for aluminum to be replaced by silver, with this layer structure preferably being used for a rear-surface mirror.

Reference List

1

Photovoltaic space module

2

spacecraft membrane

3

photovoltaic element

4

adhesive layer

5

substrate

6

silicon oxide layer

7

silicon oxide layer

8th

adhesive interface

9

ITO layer

10

film web

11

adhesive interface

12

drag sail

13

ITO layer

14

membrane antenna

15

solar sail

16

aluminum layer

17

aluminum layer

18

titanium oxide layer

19

titanium oxide layer

QUOTES INCLUDED IN DESCRIPTION

This list of documents cited by the applicant was generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Patent Literature Cited

• DE 102007041410 B4 [0005]
• DE 102017101178 A1 [0019]
• DE 102016101430 B4 [0019]

Claims (16)

Self-supporting flexible spacecraft membrane (2) with a substrate (5) made of a fluorinated plastic, characterized in that the spacecraft membrane (2) has a silicon oxide layer (6; 7). Spacecraft membrane (2) after claim 1 , characterized in that the fluorinated plastic a) a florpolymer polymer based on fluorocarbons with multiple carbon-fluorine bonds and / or b) PTFE and / or c) FEP and / or d) PFA and / or e) a mix consists of several fluoromonomers and/or f) THV and/or g) ETFE and/or h) ECTFE and/or i) PVDF. Spacecraft membrane (2) according to one of the preceding claims, characterized in that the spacecraft membrane (2) is transparent. Spacecraft membrane (2) according to one of the preceding claims, characterized in that there is an ITO layer (9; 13) and/or a titanium oxide layer (18; 19) on at least one side of the substrate (5). Spacecraft membrane (2) according to one of the preceding claims, characterized in that the substrate (5) is coated on at least one side with an aluminum layer (16; 17) and/or a silver layer. Spacecraft membrane (2) according to one of the preceding claims, characterized in that the silicon oxide layer (6, 7) and/or the ITO layer (9; 13) and/or the titanium oxide layer (18; 19) as an adhesive interface (8; 11) trained or used. Spacecraft membrane (2) after claim 6 , characterized in that an acrylic or silicone adhesive is arranged on the adhesive interface (8; 11). Spacecraft membrane (2) according to any one of the preceding claims, characterized in that the spacecraft membrane (2) is in a packed state. Spacecraft membrane (2) according to one of the preceding claims, characterized in that the spacecraft membrane (2) has at least one glued-on crack propagation impeding element. Photovoltaic space module (1) with a) a photovoltaic element (3) and b) a spacecraft membrane (2) according to any one of the preceding claims, wherein c) the photovoltaic element (3) is glued to the spacecraft membrane (2) and d) a cross-section of the spacecraft membrane (2) a da) a silicon oxide layer (6) to which the photovoltaic element (3) is glued, db) a substrate (5) made of a fluoropolymer or FEP, dc) a silicon oxide layer (7) and dd) has an ITO layer (9) or a titanium oxide layer (19). Resistance sail (12) with a) a spacecraft membrane (2) according to one of Claims 1 until 9 , wherein b) a cross section of the spacecraft membrane (2) ba) a silicon oxide layer (6), bb) a substrate (5) made of a fluoropolymer or FEP, bc) a silicon oxide layer (7) and bd) an ITO layer (9; 13 ) or a titanium oxide layer on an outside of a silicon oxide layer (6; 7) or an ITO layer (9, 13) or a titanium oxide layer on the outside of the silicon oxide layers (6, 7). Resistance sail (12) after claim 11 , characterized in that the resistance sail (12) has a plurality of foil webs (10a, 10b, ...), which a) each as a spacecraft membrane (2) according to one of Claims 1 until 9 are formed and b) are glued together at their edges, the at least one ITO layer (9, 13) or titanium oxide layer forming an adhesive interface between the foil webs (10a, 10b, ...). Resistance sail (12) after claim 11 or 12 , characterized in that the resistance sail (12) has a film web (10a; 10b; ...) which has a bonded reinforcement in the area of one edge, the at least one ITO layer (9, 13) or titanium oxide layer having an adhesive interface for forms the reinforcement. Reflective membrane antenna (14), reflector antenna or reflective solar sail (15) with a spacecraft membrane (2) according to one of Claims 1 until 9 , wherein a cross-section of the spacecraft membrane (2) a) a silicon oxide layer (6) b) a substrate (5) made of a fluoropolymer or FEP, c) a silicon oxide layer (7) and d) an aluminum layer (16; 17) on an outside of a silicon oxide layer (6; 7) or an aluminum layer (16, 17) on each outside of the silicon oxide layers (6, 7). Reflective membrane antenna (14), reflector antenna or reflective solar sail (15) with a spacecraft membrane (2) according to one of Claims 1 until 9 , wherein a cross-section of the spacecraft membrane (2) has a) an aluminum layer (16), b) a substrate (5) made of a fluoropolymer or FEP, c) an aluminum layer (17) and d) a silicon oxide layer (6; 7) or titanium oxide layer an outside of an aluminum layer (16; 17) or a respective silicon oxide layer (6, 7) or titanium oxide layer on the outside of the aluminum layers (16, 17). Use of a spacecraft membrane (2) according to one of Claims 1 until 9 as a) carrier membrane for photovoltaic elements (3) and/or b) resistance sails (12) and/or c) membrane antenna (14) or reflector antenna and/or d) photovoltaic space module (1).

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