Abstract:
The invention is a satellite assembly comprising at least three flat housings in a plane for containing the payload of the satellite, each housing having at least two inflatable tubular members coupled by a first end thereto and by their second ends to separate adjacent housings. The individual housings have protrusions about their respective peripheries for attaching the tubular members at least equal to the number of the tubular members coupled thereto.

Description:
REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation-in-part of Provisional Patent Application Serial No. 60/145,166 “Nano Satellite Formation Flying System”, filed Jul. 22, 1999. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The invention relates to the field of satellites and, in particular, to inflatable satellites. 
     2. Description of Related Art 
     Inflatable satellites are old in the art. For example, the ECHO satellite launched in the early dates of space flight was a large balloon with a reflective coating. Of course, later designs such as disclosed in U.S. Pat. No. 5,386,953, entitled “Spacecraft Designs For Satellite Communication System,” by J. R. Stuart were a far more sophisticated communications satellite design including an inflatable torus shaped structure incorporating an array of antennas and solar cells. However, this design does not store in a very small volume, nor is it light in weight. In addition, continued pressurization is required to insure that its shape is maintained. Thus a large supply of pressurized gas is required in order to maintain internal pressurization over a long time period. The patent to J. R. Stuart also discloses a hemispherical shaped satellite design using a tubular truss assembly to support a series of antennas that allows stacking of a series thereof. While this design allows for storing a significant number of satellites in a relatively small volume, the satellite is not designed to be collapsed into a very small volume. Therefore there is the need for a low cost and small size satellite that can be used for missions requiring small payloads and which can easily be scaled up to handle larger payloads. 
     Thus, it is a primary object of the invention to provide an inflatable satellite design. 
     It is another primary object of the invention to provide an inflatable satellite design that stores in a very small volume when un-inflated. 
     It is a further object of the invention to provide an inflatable satellite design that once inflated remains rigidized upon elimination of internal pressurization. 
     It is a still further object of the invention to provide an inflatable satellite design that can be easily scaled up in size. 
     SUMMARY OF THE INVENTION 
     The invention is a satellite assembly comprising at least three flat housings in a plane for containing the payload of the satellite, each housing having at least two inflatable tubular members coupled by a first end thereto and by their second ends to separate adjacent housings. The individual housings have protrusions about their respective peripheries for attaching the tubular members at least equal to the number of the tubular members coupled thereto. 
     For standardization purposes, the housings have six equally spaced protrusions extending from the periphery thereof. At least one of the housing includes a mechanism for internally pressurizing said tubular members such that they become inflated and rigid. 
     The assembly further includes a system for insuring that the tubular members remain in the inflated condition without internal pressurization. This system preferably comprises a fibrous inner layer of material impregnated with an ultraviolet radiation curing resin. Thus when the satellite assembly is placed in orbit, ultraviolet radiation from the sun will cure the resin and simultaneously bond the fibrous layer to the outer layer, thereby rigidizing the tubular member. The preferred configuration of the satellite assembly comprises  10  housings in a triangular pattern. 
     The novel features which are believed to be characteristic of the invention, both as to its organization and method of operation, together with further objects and advantages thereof, will be better understood from the following description in connection with the accompanying drawings in which the presently preferred embodiments of the invention are illustrated by way of example. It is to be expressly understood, however, that the drawings are for purposes of illustration and description only and are not intended as a definition of the limits of the invention. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a top view of a first embodiment of the satellite assembly having three housings. 
     FIG. 2 is a top view of a second embodiment of the satellite assembly having ten housings 
     FIG. 3 is partial cross-sectional view of FIG. 1 illustrating the construction of the tubular member connecting two of the housings. 
     FIG. 4 is a schematic of a pressurization system for inflating the satellite from the stored position to the deployed position. 
     FIG. 5 is a view of satellite shown in FIG. 2 in the stored condition and in the intermediate steps to the deployed position. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Referring to FIG. 1, the satellite, generally indicated by numeral  10  includes three identical circular housings  11 ,  12  and  13  all having top surfaces  14 , bottom surfaces  15  and peripheral side surfaces  16 . The housings  11 ,  12 , and  13  contain the satellite payload  18  and other equipment necessary for operating the satellite, which may vary from housing to housing. 
     1. The housing  11  includes six tubular mounting members  22 ,  23 ,  24 ,  25 ,  26  and  27 . 
     2. The housing  12  includes six tubular fittings  28 ,  29 ,  30 ,  31 ,  32 , and  33 . 
     3. The housing  13  includes six tubular fittings  34 ,  35 ,  36 ,  37 ,  38  and  39 . 
     All the tubular fittings extend from the peripheral side surface  16  of each housing  11 ,  12 , and  13  equally spaced at 60 degrees from each other. Although, in this application, there could be as few as two at 60 degrees apart. However, because of the building block approach of this satellite design, six equally spaced tubular mounting members are preferred. A tube  42  is mounted by a first end  44  to a member  22  of housing  11  and by a second end  46  to member  28  of housing  12 . A second tube  48  is mounted by a first end  50  to fitting  29  on the housing  12  and by a second end  51  to housing  13 . Finally, a third tube member  52  is mounted by a first end  53  to fitting  35  of housing  13  and by a second end  54  to fitting  23  of housing  11 . Thus a triangular shaped satellite assembly is formed having an included angle 55 of 60 degrees between the housings. 
     The tubes  42 ,  48  and  52  are all identical and thus only tube  42  will be discussed in detail. Preferably, the tube  42 , is made of an outer layer  62  of a material such as a polyimide, for example Kapton® manufactured by E. I. duPont de Nemours &amp; Company, Williamsburg, Del. Such materials can serve as a pressure barrier. The inner layer  64  is made of a fiber-reinforced layer impregnated with an ultraviolet radiation curable resin. The inner layer  64  can be made of such materials as a liquid crystal thermotropic (melt spun) polyester polyarylate fiber, for example VECTRAN® manufactured by Hoechat Celanese, Charlotte, N.C. or SPECTRA® manufactured by Allied Signal, Petersberg, Va. to carry the axial loads. Another high strength material is a lyotropic (solvent spun) aromatic polyaramide fiber, such as KEVLAR®, which is manufactured by E. I. duPont de Nemours &amp; Company. There is any number of usable ultra-violet radiation curable resins, for example, U.S. Pat. No. 4,999,136 “Ultra Violet Curable Conductive Resin” by W. A. Su; et al discloses a suitable resin. 
     The first end  44  of the tube  42  is bonded to the member  22  of the housing  11  and is additionally secured by a clamp  66 , while the second end  46  is bonded to tubular member  28  on housing  12  and additionally secured with a clamp  68 . Bonding can be accomplished by exposing the ends  44  and  46  of tube  42  only to ultra-violet radiation. This easily accomplished by masking off all of the tube  42  excepting the ends, prior to exposure to the radiation. Tubes  48  and  52  are joined to housings  11 ,  12  and  13  in a similar manner. 
     In FIG. 2 is a ten housing satellite assembly, generally designated by numeral  60 , built upon the satellite assembly shown in FIG.  1 . Additional tubular members  80  creating a larger satellite assembly join additional housings  70 ,  72 ,  73 ,  74 ,  75 ,  76 , and  77 . In fact, and combination of housings can be used as long as there are at least three housings and each housing in joined by at least two tubular members to other housings. 
     Still referring to FIGS. 2 and 3 and additionally to FIG. 4 the satellite further includes a gas system  82  mounted in one or more of the housings and connected to the tubular members by lines  83  (see FIG. 4) comprising a pressurized gas source  84  coupled to a control valve  85  and regular  86  via line  88 . An electronic controller  90  controls the system  82 . Thus upon opening of the valve  85 , the tubes  42 ,  48 , and  52  are pressurized and expand and become rigid. Once in space, the resin impregnating the inner layer  64  becomes cured by exposure to ultra-violet radiation from the sun and rigidizes the tubes. 
     Sill referring to FIGS. 2-4 and additionally to FIG. 5, the satellite  60  is stored in the stored position, indicated by numeral  60 ′ during launch and release into orbit. Upon reaching orbit in space, the stored gas system  82  is activated causing the tubes  42 ,  48 ,  52  and  80  to expand and become rigid, and opened to an intermediate position  60 ″ and finally to the fully open position  60 . After that, ultraviolet radiation from the sun will cause curing resin in the inner layer  64  of the tubes causing the tubes to become permanently rigid. Thus if gas pressure is lost over time, the tubes will still remain ridged. It should be noted that solid state gas generation systems can be also be used. In addition, mechanical rigidizing systems are useable. 
     While the invention has been described with reference to particular embodiments, it should be understood that the embodiments are merely illustrative, as there are numerous variations and modifications, which may be made by those skilled in the art. Thus, the invention is to be construed as being limited only by the spirit and scope of the appended claims. 
     Industrial Applicability 
     The invention has applicability to the satellite manufacturing industry.