Patent Application
20240383215
The present invention relates to space stiffening material, and more particularly, to a material that stiffens post deployment in space with increasing and tailorable stiffness and rigidity in post-deployed structures.
Large structures (e.g., antennas, solar sails, habitats, and reflectors) prior to being deployed in space are folded up for stowage in launch vehicle fairings. These structures, when deployed from the launch vehicle, are opened up and held rigid through internal structural elements (booms), guy lines, gas pressure, or rotational forces. Even with these internal structural elements; billowing, flexing, and bending of the structure or material may occur due to the structure material being extrinsically flexible. These structures also may collapse from the single point failure of a structural element.
To resolve this issue, stiffening and dampening solutions may be used. For example, large space based antennas are held in place using guy wires, or using a variety of materials and material thicknesses in the structure, with some being employed to dampen flexing, such as ribs, or large lattices and struts being constructed from ever larger and stiffer structures.
However, stiffening and dampening solutions increase mass and complexity to give the necessary strength to resist deformation under loading. For example, structural elements that add mass also add complexity to deliver with the folding and flexibility that was required for launch storage but hinders the mission. Large unfolding scaffolds need to be able to expand from compact stowage to fit in the launch vehicle fairing, but need to reliably unfold and extend, without adding mass to the launch. Guy wires suffer from tangling and unspooling risks during deployment, often requiring multiple motors to wind out the wires and maintain tension throughout deployment. Unfolding booms or scaffolds have multiple hinges that may fail upon deployment.
Accordingly, an improved self-stiffening space material may be beneficial.
Certain embodiments of the present invention may provide solutions to the problems and needs in the art that have not yet been fully identified, appreciated, or solved by current stiffening and dampening solutions. For example, some embodiments of the present invention pertain to space stiffening material configured to increase stiffness and rigidity in post-deployed structures.
In one embodiment, a method for stiffening space stiffening material on a structure in space includes deploying a structure from a payload of a launch vehicle, wherein the structure is composed of the space stiffening material. The method also includes orienting the space stiffening material towards the ultraviolet (UV) light emanating from the sun in order to increase the strength and rigidity of the space stiffening material.
In order that the advantages of certain embodiments of the invention will be readily understood, a more particular description of the invention briefly described above will be rendered by reference to specific embodiments that are illustrated in the appended drawings. While it should be understood that these drawings depict only typical embodiments of the invention and are not therefore to be considered to be limiting of its scope, the invention will be described and explained with additional specificity and detail through the use of the accompanying drawings, in which:
There are classes of this space stiffening material (e.g., polymers and resins) that may be cured under ultraviolet (UV) illumination to become rigid. Some embodiments utilize solar UV light, which is present in near Earth space (i.e., almost 30 times more than is present on Earth's surface), to perform the stiffening of the space stiffening material. This space stiffening material is configured to increase its stiffness and the rigidity of post-deployed structures. For example, the space stiffening material, which increases its stiffness or rigidity post-deployment in space, is used, allowing the structure to be folded and stored compactly in a payload from launch to the deployment location in space prior to stiffening. This structure, which was compactly stored, can be deployed to its larger, open structure, and may undergo a chemical change to increase the rigidity of the space stiffening material when exposed to solar UV irradiation after it has been deployed. For example, a polymer system increases the structure's stiffness or rigidity under the exposure of the solar UV light.
In short, materials composed of UV sensitive polymers may undergo solar UV photoinduced polymerization through the activation of photoabsorbing chemical groups under the exposure of solar illumination in space. Structures employing these materials may open up or be opened in space, and may be controllably exposed to the solar illumination containing UV light. These materials undergo chemical reactions when exposed to solar UV light leading to further polymerization processes that increases the stiffness of the materials. This post deployment stiffening reaction, which can include polymerization (i.e., separate from any initial polymerization on Earth for material fabrication) increases the space stiffening material's intrinsic rigidity and allows the space stiffening material to retain its shape after solar irradiation. This intrinsic material stiffness leads to extrinsic rigidity of the structure composed of these materials, reducing the need for external stiffening from scaffolds, guy wires, inflation, or rotation, thus reducing cost, weight and complexity of the structure and improving structure performance.
In one embodiment, to stiffen the material in space, solar UV light already present in space (i.e., 30× more than the presence on Earth) is used. For example, instead of having an external (or internal) UV light source to stiffen the space stiffening material, the space stiffening material is controllably exposed to the sun, and the sun's UV illumination (not shielded by the ozone layer or atmosphere) triggers a chemical reaction that stiffens the material. This controlled exposure process of the material to the sun may involve active movement of the material structure towards the sun through the use of the structure's attitude control system (ACS) (e.g., thrusters or reaction wheels/rods), through the use of the induced rotation of the structure through solar illumination, or through the procession of the object in space.
These space stiffening materials can be used for inflatable habitats, which can be expanded using methods such as gas inflation or deployed internal or external struts, and this structure can then be stiffened by the UV light from the sun. The inflation mechanism would no longer be needed to retain the deployed structure shape and the expansion mechanism or gas could be redeployed for other habitats or structures. For example, gas may be used to inflate a volume contained by these space stiffening materials, and then once the material becomes stiff under solar illumination, the gas could be recaptured for inflation of other volumes. Alternatively, an internal or external structure could be used to open up the volume, which would become stiff, and then the structure could be redeployed elsewhere. These habitats or structures can be volumes for human occupied space, storage, laboratories, or other useful volumes in space. By using this technique, high positive pressure is no longer required to maintain the form of the structure through inflation, allowing the structure to retain is shape in the event of puncture or other inflation failure, as well as retaining structure if any scaffolding fails, or for use as an uninflated volume.
For solar sails, a large structure is deployed and momentum transfer is used to direct sunlight to hit the sail to move the payload along. However, constraints such as billowing of the sails needs to be minimized. These may be minimized by using struts and structures. However, if the material can be stiffer, then the efficiency of momentum transfer may be increased to the material such that the billowing is minimal and or the struts or structures can be reduced or eliminated. By increasing the stiffness of the solar sail material this billowing and flexing can be reduced, increasing the energy transfer and efficiency of the vehicle.
For a deployed space large antenna dish, the effectiveness of the antenna to send or receive information is directly impacted not only by the absolute size of the collection dish, but also by the effectiveness by the dish reflects the photons to the dish receiver. These dishes must be rigid and not suffer from warping, twisting, or billowing to prevent reductions in dish effectiveness. By making the dish material from material that stiffens after deployment into the optimal shape, dish capability is maintained. This dish could then be made from the space stiffening materials, and in their pre-stiffened state can be manufactured on Earth and then folded up for stowage in a launch vehicle. After launch and deployment the dish can be unfolded and deployed in its final shape. This shape can then be maintained by converting the material from a flexible, foldable form into a stiffer form through controlled exposure of the material to the solar UV illumination, converting the material into its final, stiff form.
In some embodiments, these materials can be employed in extraterrestrial applications beyond space orbits or transits, including on lunar, Martian, or other body locations. In these embodiments, deployment of the material and its structure can be performed on the surface of a moon, asteroid, planet or other body where sufficient solar illumination exists. These structures would still need compact packing for transport to this destination, and unfolding at their destination. For example, the lengthy lunar day (˜14 days) and no atmosphere to absorb solar UV, means that the flux of UV light from the sun is equivalent whether on the moon's surface or in space. This allows for post deployment stiffening of materials on these bodies similarly to in-space stiffening. This enables lunar or Martian habitats that can be inflated with precious gasses that can be recaptured, and prevents the habitat from collapsing from a pressure loss.
In some embodiments, there may be multiple approaches to increase stiffness of the space stiffening material.
In one embodiment, solid polymer matrix with UV activatable monomers are dissolved in the solid polymer matrix. This solid polymer matrix would have structural integrity (i.e., holds/maintains it shape rather than tearing or falling apart), but still be a flexible material. This would enable fabrication of objects on Earth. The UV activatable monomers would be dispersed, dissolved, or mixed in the solid matrix. In this embodiment, post deployment the solar UV radiation would cause photochemical activation of the UV activatable monomers to form a bipolymer system with increased stiffness. The monomers would react with each other and not with the solid polymer matrix. The monomers would form long chains of oligomers within the solid polymer matrix, creating a two component material with the new photo created oligomers running throughout the solid polymer matrix, increasing the stiffness of the combined material. The solid polymer matrix and monomer material would then be a transformed to a new material resulting from the UV activated monomer units forming chemical bonds with each other within the solid polymer matrix, which then creates a new material with a higher stiffness than the initially flexible solid polymer matrix+UV activatable monomer system. The UV activatable components may be monomers, dimers, trimers, or other short chain molecules capable of forming long chains upon UV activation.
In another embodiment, the UV activatable monomers may react with the solid polymer matrix and create a new chemical structure from the polymer matrix plus monomer. This post-UV reaction material is formed from the matrix reacting with the monomers mixed within it post solar UV activation. This solar induced reaction increases the extrinsic stiffness of the new solid polymer matrix through reacting with the UV activatable monomer component. See, for example,
In another embodiment, one or more solid polymer(s) with UV activatable crosslinking sections may be used. In this embodiment, the UV radiation activates side chains or polymer unit sections, which causes crosslinking between existing polymer chains, thereby increasing the material stiffness. See, for example,
In yet another embodiment, a partial UV illumination is used to achieve strength for fabrication and packaging. Using the same reactions and materials as seen in diagrams 100 and 200, these materials can be initially reacted on Earth using UV sources, such as UV lamps, to create a desired stiffness for the materials necessary for terrestrial fabrication, packing, and transport to space. Thereafter, a final solar UV exposure is used to achieve final desired properties. See, for example,
In another embodiment, large space structures, such as space antenna structure 704, may conventionally be deployed using barrel struts 705 to open up antenna surface 706. However, by replacing material (or antenna surface) 706 with a space stiffening material that becomes rigid under solar UV illumination, the mass of antenna structure 706 may be reduced by eliminating the need for the barrel structure, and may reduce antenna surface 706 undulation, thereby improving antenna function.
In another embodiment, structure 707 is held open through rotation of material 708 through propulsion of units 709 generating a centrifugal force that pulls open material 708 and taut through continued rotation. By using solar UV stiffened material, the continued rotation is no longer needed to keep material 708 taut, and allows for the elimination of rotational elements 709. This removal of the necessity for rotation allows for easier maneuvering and orientation of structure 707 as there would not be rotational inertia to counter.
In short, these embodiments use different techniques to start with a solid (but flexible) material, and transform the solid into a more rigid material. Rigidity is an extrinsic, external property of the structure the material comprises. Increasing the intrinsic stiffness of the material results in a structure that is extrinsically rigid. Altering the material properties through solar illumination after the structure is deployed results in a more rigid structure that needs less structural support, and creates a more durable, stiff, lighter, and reliable.
In addition to creating uniform, stiff materials for space structures, this method can also create structures with joints or intended points of flexion through the controlled and selective illumination of the solar UV stiffened material. See, for example,
It will be readily understood that the components of various embodiments of the present invention, as generally described and illustrated in the figures herein, may be arranged and designed in a wide variety of different configurations. Thus, the detailed description of the embodiments of the present invention, as represented in the attached figures, is not intended to limit the scope of the invention as claimed, but is merely representative of selected embodiments of the invention.
The features, structures, or characteristics of the invention described throughout this specification may be combined in any suitable manner in one or more embodiments. For example, reference throughout this specification to “certain embodiments,” “some embodiments,” or similar language means that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment of the present invention. Thus, appearances of the phrases “in certain embodiments,” “in some embodiment,” “in other embodiments,” or similar language throughout this specification do not necessarily all refer to the same group of embodiments and the described features, structures, or characteristics may be combined in any suitable manner in one or more embodiments.
It should be noted that reference throughout this specification to features, advantages, or similar language does not imply that all of the features and advantages that may be realized with the present invention should be or are in any single embodiment of the invention. Rather, language referring to the features and advantages is understood to mean that a specific feature, advantage, or characteristic described in connection with an embodiment is included in at least one embodiment of the present invention. Thus, discussion of the features and advantages, and similar language, throughout this specification may, but do not necessarily, refer to the same embodiment.
Furthermore, the described features, advantages, and characteristics of the invention may be combined in any suitable manner in one or more embodiments. One skilled in the relevant art will recognize that the invention can be practiced without one or more of the specific features or advantages of a particular embodiment. In other instances, additional features and advantages may be recognized in certain embodiments that may not be present in all embodiments of the invention.
One having ordinary skill in the art will readily understand that the invention as discussed above may be practiced with steps in a different order, and/or with hardware elements in configurations which are different than those which are disclosed. Therefore, although the invention has been described based upon these preferred embodiments, it would be apparent to those of skill in the art that certain modifications, variations, and alternative constructions would be apparent, while remaining within the spirit and scope of the invention. In order to determine the metes and bounds of the invention, therefore, reference should be made to the appended claims.
