Patent Publication Number: US-9403606-B2

Title: Spacecraft radiator panels

Description:
RELATED APPLICATION 
     The present application is a continuation-in-part of, and claims priority to, U.S. patent application Ser. No. 13/412,906, which was filed on Mar. 6, 2012, and the complete disclosure of which is hereby incorporated by reference. 
    
    
     FIELD 
     The present disclosure relates to spacecraft radiator panels. 
     BACKGROUND 
     Spacecraft include a plethora of equipment, such as electronic equipment, that generates heat. This heat must be dissipated, and because space is essentially void of air, the heat must be radiated to outer space. Spacecraft, such as satellites, typically include radiator panels that draw the heat from electronics and other equipment to an outer surface of the spacecraft. 
     With reference to the schematic diagram of  FIG. 1 , a typical prior art radiator panel  10  includes an inside face-sheet  12  that faces the inside of the spacecraft, an outside face-sheet  14  that faces the outside of the spacecraft toward outer space, a honeycomb core  16  positioned between the face-sheets to give the panel structural support, and one or more heat pipes  18  positioned between the face-sheets to translate the heat generated by an electronics package  20  away from the electronics package  20  to the outside face-sheet  14  and ultimately to outer space. Heat pipes are heat transfer devices that rely on phase transition of a working fluid to transfer heat from one location to another, such as from an electronic device to a heat sink, or in the application of a spacecraft, ultimately to outer space. 
     As seen in  FIG. 1 , the heat pipe  18  of the illustrated prior art radiator panel  10  includes a flange  22  extending from a body  24 , with the flange  22  partially penetrating, or extending through, the inside face-sheet  12 . The electronics package  20  is mounted to the flange  22  with a gasket  26  positioned between the electronics package  20  and the flange  22 , and heat from the electronics package  20  conducts through the flange  22  to the body  24  of the heat pipe  18 , for subsequent dissipation to outer space as discussed above. Because the flange  22  of the heat pipe  18  partially penetrates the inside face-sheet  12 , the inside face-sheet  12  is required to be modified during assembly of the prior art radiator panel  10 . That is, the inside face-sheet  12  is required to be machined, or otherwise modified, to include an opening  28  for the flange  22  to partially extend through. Moreover, because the body  24  of a flanged heat pipe  18  typically is extruded, the flange  22  initially extends the entire length of the heat pipe  18 . Accordingly, during assembly of a typical prior art radiator panel  10 , the flange  22  must be modified to only extend for a distance corresponding to a dimension of a package  20 . Also, the honeycomb  16  is required to be modified to extend around the heat pipe  18 , including the flange  22  of the heat pipe  18 . This process during assembly of a radiator panel  10  may be referred to or described as core-stepping. During assembly of a prior art radiator panel  10 , bolts  29  are utilized to secure the electronics package  20  to the heat pipe&#39;s flange  22 . 
     As schematically illustrated in dashed lines in  FIG. 1 , prior art radiator panels  10  may include one or more stiffening members  19 , such as in the form of an I-beam, on the internal surface of the inside face-sheet  12  to give the radiator panel  10  a desired stiffness. However, placement of stiffening members  19  presents several challenges with the design of prior art radiator panels  10  because of the various packages  20  and associated electronics, wiring harnesses, and other internal components of a spacecraft. 
       FIG. 2  schematically illustrates another typical prior art radiator panel  11 . Prior art radiator panel  11  also includes an inside face-sheet  12 , an outside face-sheet  14 , a honeycomb core  16 , and one or more heat pipes  18  for drawing heat away from an electronics package  20 . The heat pipe  18  of prior art radiator panel  11 , however, does not include a flange  22  that penetrates the inside face-sheet  12 . Rather, prior art radiator panels  11  include epoxy-potted fasteners  13  that are positioned within bores  15  that are required to be machined through the inside face-sheet  12  and into the honeycomb core  16 . Fasteners  13  receive bolts  29 , and typically a layer of room-temperature vulcanizing (RTV) silicone sealer  17  is utilized between the electronics package  20  and the inside face-sheet  12 . Fasteners  13  are not in mechanical communication with and do not engage the heat pipe  18 . The joints formed by fasteners  13  and bolts  29  are subject to relaxation over time, and thus to mechanical creep, which results in an inefficient transfer of heat from the electronics package  20  to the heat pipe  18 , and thus in an inefficient transfer of heat from the electronics package  20  to outer space. 
     Prior art radiator panels often include heat pipes that are over-sized, or that have the capability of transferring more heat than is required for the prior art radiator panel, because a desired stiffness of the radiator panel needs to be achieved. In other words, radiator panels of spacecraft are required to have an optimized stiffness in view of the conditions in which the spacecraft is launched, and the size of heat pipes are selected to achieve the optimized stiffness. 
     SUMMARY 
     Spacecraft, radiator panels for spacecraft, kits for radiator panels, inserts associated with radiator panels, heat pipes associated with radiator panels, external structural reinforcement members associated with radiator panels, and methods of assembling radiator panels are disclosed herein. Some radiator panels according to the present disclosure include two spaced-apart face-sheets, a core positioned between the face-sheets, and at least one external structural reinforcement member that extends across an external side of the outside face-sheet. In some embodiments, a plurality of external structural reinforcement members extends across the external side of the outside face-sheet. In some embodiments, the outer surface of the external structural reinforcement members reflects a substantial amount of incident light of the outer surface away from the outside face-sheet. Some embodiments of radiator panels according to the present disclosure have less mass and/or have less thickness than comparably stiff and sized radiator panels without external structural reinforcement members. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a schematic profile view of a prior art radiator panel for a spacecraft. 
         FIG. 2  is a schematic profile view of another prior art radiator panel for a spacecraft. 
         FIG. 3  is a schematic representation of an illustrative, non-exclusive example of a spacecraft according to the present disclosure in the form of a satellite. 
         FIG. 4  is a schematic diagram representing radiator panels according to the present disclosure. 
         FIG. 5  is a schematic plan view of a portion of a radiator panel including illustrative, non-exclusive examples of inserts according to the present disclosure. 
         FIG. 6  is another schematic plan view of a portion of a radiator panel including illustrative, non-exclusive examples of inserts according to the present disclosure. 
         FIG. 7  is another schematic plan view of a portion of a radiator panel including illustrative, non-exclusive examples of inserts according to the present disclosure. 
         FIG. 8  is a schematic profile view of an illustrative, non-exclusive example of a radiator panel according to the present disclosure, including illustrative, non-exclusive examples of inserts and a heat pipe according to the present disclosure. 
         FIG. 9  is an isometric fragmentary view of a portion of an illustrative, non-exclusive example of a radiator panel according to the present disclosure, including an external structural reinforcement member. 
         FIG. 10  is a fragmentary cross-sectional view of the radiator panel of  FIG. 9 , taken along line  10 - 10 , and also schematically illustrating additional non-exclusive examples of external reinforcement members according to the present disclosure. 
     
    
    
     DESCRIPTION 
     Spacecraft, radiator panels for spacecraft, kits for radiator panels, inserts associated with radiator panels, heat pipes associated with radiator panels, external structural reinforcement members, and methods of assembling radiator panels are disclosed herein. 
       FIG. 3  schematically represents illustrative, non-exclusive examples of spacecraft  30  in the form of satellites  32 . However, other types of spacecraft  30  are within the scope of the present disclosure, and radiator panels, and associated components and kits, according to the present disclosure are not limited to being used with satellites  32 . A satellite  32  includes a body  34  and at least one radiator panel  35 , with the radiator panel  35  typically forming a wall, or other structural member, of the satellite&#39;s body  34 . Spacecraft  30 , including satellites  32  or other spacecraft, may include any number of radiator panels  35 , including one, two, three, four, or more radiator panels  35 . Radiator panels  35  additionally or alternatively may be described as radiators  35 , radiator assemblies  35 , and/or radiator panel assemblies  35 . Some radiator panels  35  may be described as for use with high-powered units. For example, a radiator panel  35  may be configured to dissipate greater than 10 watts per square inch of radiator panel  35 ; however, values less than this value are within the scope of the present disclosure and may be associated with the heat dissipation of a radiator panel  35 . 
     As schematically illustrated in  FIG. 3  in dashed lines, radiator panels  35  typically include a network  38  of heat pipes  40  that are components of, positioned within, coupled to, or otherwise associated with a radiator panel  35 . Networks  38  additionally or alternatively may be described as heat pipe networks  38 . The schematic representation of six heat pipes  40  in  FIG. 3  is illustrative only, and any number of heat pipes  40  may be associated with a radiator panel  35 , including one or more heat pipes  40 . In  FIG. 3 , five heat pipes  40  are illustrated as extending in a generally horizontal direction and a single heat pipe  40  is illustrated as extending in a generally vertical direction; however, any suitable orientation of heat pipes  40  may be used, and radiator panels  35  are not limited to including orthogonally oriented heat pipes  40  relative to the overall shape of the radiator panel  35 . Moreover, while it is within the scope of the present disclosure that two heat pipes  40  associated with a radiator panel  35  are oriented transverse, and in some embodiments perpendicular, to each other, such a relationship is not required to all embodiments, and radiator panels  35  according to the present disclosure may or may not include transversely oriented heat pipes  40 . 
     As also schematically illustrated in  FIG. 3  in dashed lines, radiator panels  35  may include (but are not required to include) one or more external structural reinforcement members  200 . These optional external structural reinforcement members  200  may take any suitable form and may be used to stiffen, or otherwise define a desired stiffness of, a radiator panel  35 . An external structural reinforcement member  200 , when provided, is positioned on the external side of the radiator panel  35 , and therefore it is exposed to outer space and any light that is incident upon the radiator panel  35 . In some embodiments, such as schematically illustrated in  FIG. 3 , the external structural reinforcement members  200  may span the entire width, or at least substantially the entire width, of the radiator panel  35 ; however, such a configuration is not required, and as schematically illustrated by the dash-dot lines in  FIG. 3 , an external structural reinforcement member  200  may extend for only a portion of the width of the radiator panel  35 . Moreover, while the optional structural reinforcement members  200  of  FIG. 3  are illustrated in generally orthogonally oriented and parallel positions relative to the overall shape of the radiator panel  35 , such configurations are not required, and any suitable number, position, and configuration of optional external structural reinforcement members  200  may be used, for example, depending on the application of the radiator panel  35  or spacecraft  30 , depending on a desired stiffness of the radiator panel  35 , depending on a desired mass of the radiator panel  35 , and/or depending on other properties and characteristics of radiator panels  35  and/or spacecraft  30 . 
       FIG. 4  schematically represents radiator panels  35 , which may include radiator panels  36  and radiator panels  202  according to the present disclosure. As schematically illustrated, a radiator panel  35  typically includes an inside face-sheet  42 , an outside face-sheet  44 , at least one heat pipe  40 , and a core  50 . As schematically illustrated in dashed lines in  FIG. 4 , a radiator panel  35  additionally may include a package  52  that is secured to the inside surface of the inside face-sheet  42 . As used herein, the relative terms ‘inside’ and ‘outside’ and similar relative terms, such as ‘internal’ and ‘external,’ refer to inside and outside of the spacecraft  30 , with which the radiator panel  35  is associated. Accordingly, the inside face-sheet  42  of a radiator panel  35  is positioned on the inner side of the radiator panel  35  when the radiator panel  35  is installed on a spacecraft  30 . Likewise, the outside face-sheet  44  of a radiator panel  35  is positioned on the outer side of the radiator panel  35  when it is installed on a spacecraft  30 . Other relative terms used herein, such as ‘left’ and ‘right’ refer to the orientation of the drawing to which is being referred and do not limit the scope of structure being described. 
     The inside face-sheet  42  and the outside face-sheet  44 , collectively may be referred to herein as two spaced-apart face-sheets. The face-sheets may be constructed of any suitable material, including (but not limited to) aluminum, aluminum alloy, titanium, titanium alloy, and steel, including stainless steel. In some embodiments, although not required, the outside face-sheet  44  may include a mirrored outer surface  54 , such as to enhance the heat transfer properties of the radiator panel  35 . In some embodiments, one or more of the two spaced-apart face-sheets may be constructed of the same material as a heat pipe  40 . Additionally or alternatively, two or more of the face-sheets and the heat pipe(s)  40  may be constructed of materials that have a similar or identical thermal coefficient of expansion. 
     As discussed in more detail herein, some radiator panels  35  may not require penetration of the outside face-sheet  44  for appropriate mounting and securing of heat pipes  40  and associated packages  52 . Accordingly, in embodiments that include a mirrored outer surface  54 , the heat transfer properties of the mirrored outer surface  54  may not be compromised, such as with fasteners, brackets, and the like, in so far as a maximum surface area of the mirrored outer surface  54  may be retained. 
     Additionally or alternatively, in some embodiments, the inside face-sheet  42  may not be penetrated by a heat pipe  40  and/or an insert  48 . Stated differently, in some embodiments, the heat pipe(s)  40  of a radiator panel  35 , and/or a flange of or other structure associated with a heat pipe  40 , may not extend through an opening in the inside face-sheet  42 . Accordingly, methods of assembling radiator panels  35  may not require cutting the inside face-sheet  42  for passage of a portion of a heat pipe  40 , such as a flange associated with a heat pipe  40 . Additionally or alternatively, a method of assembling a radiator panel  35  may not include extending a portion of a heat pipe  40  through an opening in the inside face-sheet  42 . 
     Heat pipes  40  may take any suitable form. In some embodiments, a heat pipe  40  may be an off-the-shelf heat pipe. Additionally or alternatively, a heat pipe  40  may not require customization, alteration, or modification for assembly and use in a radiator panel  35 . Some embodiments of heat pipe  40  may be described as flangeless heat pipes. Moreover, as discussed, in some embodiments of radiator panels  35 , the heat pipe(s)  40  may not penetrate, or otherwise extend through, the inside face-sheet  42  and/or the outside face-sheet  44 . In some embodiments, the heat pipe(s)  40  may be positioned completely between the inside face-sheet  42  and the outside face-sheet  44 . It also is within the scope of the present disclosure that a heat pipe  40  may be positioned between the inside face-sheet  42  and the outside face-sheet  44  without penetrating either of the two spaced-apart face-sheets, but that partially extends outside of the two spaced-apart face-sheets, such as schematically illustrated in dashed lines in  FIG. 4 . Such a configuration may be desired, for example, to position an end of a heat pipe  40  so that it is completely exposed to outer space when a spacecraft  30  is in operation. 
     In some embodiments of radiator panels  35 , the heat pipe(s)  40  are operatively engaged with and in thermal communication with one or both of the inside face-sheet  42  and the outside face-sheet  44 . By ‘operatively engaged with,’ it is meant that the heat pipe  40  may be in direct physical, or mechanical, contact with one or both of the two spaced-apart face-sheets, and that the heat pipe  40  may be in indirect physical, or mechanical, communication with one or both of the two spaced-apart face-sheets, such as with a gasket or sealant positioned directly between the heat pipe  40  and a face-sheet. Accordingly, as discussed, the heat from a package  52  may conduct from the package  52 , through the inside face-sheet  42  to a heat pipe  40  for transfer of the heat away from the package  52  and ultimately to outer space during operation of the spacecraft  30 . 
     Some heat pipes  40  according to the present disclosure may include a body that is extruded, for example, from aluminum, aluminum alloy, titanium, titanium alloy, or steel, including stainless steel. Other conductive materials also are within the scope of the present disclosure and may be used, and methods other than extrusion may be used, to construct a heat pipe body. 
     The core  50  of a radiator panel  35  may take any suitable form to provide the radiator panel  35  with structural integrity. For example, the core  50  may include honeycomb or other corrugated structures that define the spacing between the inside face-sheet  42  and the outside face-sheet  44 , and that enable the overall radiator panel  35  to be low in mass, while at the same time provide for an appropriate structural integrity and internal volume for one or more heat pipes  40 . In some embodiments of radiator panels  35 , the core may not need to be altered to appropriately position one or more heat pipes  40  in a desired position between the inside face-sheet  42  and the outside face-sheet  44 . 
     Radiator panels  35  may include, or may be configured to be coupled to, any number of and any configuration of packages  52 . As used herein, a package  52  is any structure that is mounted to, or is provided for mounting to, or is desired to be mounted to, the side of the inside face-sheet  42  that faces the inside of the spacecraft  30 , and which typically produces (or transfers) heat that is desired to be transferred by a heat pipe  40  for radiation to outer space during operation of a spacecraft  30 . Illustrative, non-exclusive examples of packages  52  include (but are not limited to) electronics equipment, mechanical equipment (e.g., motors, etc.), energy generation equipment (e.g., batteries, fuel cells, etc.), as well as heat pipes  40  of a heat pipe network  38 . While only one package  52  and one heat pipe  40  are schematically illustrated in  FIG. 4 , any number of packages  52  and heat pipes  40  may be included or used with a radiator panel  35 . 
     In  FIG. 4 , package  52  is illustrated as overlapping heat pipe  40 , schematically representing a conductive relationship between the package  52 , the heat pipe  40 , and the inside face-sheet  42 . In other words, as discussed herein, a package  52  is mounted to the inside face-sheet  42  so that heat will conduct from the package  52 , through the inside face-sheet  42 , to the heat pipe  40 , so that the heat pipe  40  can transfer the heat away from the package  52  and ultimately to outer space during operation of a spacecraft  30 . In some embodiments, a package  52  is secured to the inside face-sheet  42  opposite, and in some embodiments directly opposite, a heat pipe  40 . 
     In some embodiments, a package  52  may be adhered, or sealed, to the inside face-sheet  42 . Additionally or alternatively, a gasket may be operatively positioned between and engaged with a package  52  and the inside face-sheet  42 . Accordingly, a package  52  may be described as being operatively engaged with, including operative thermal and mechanical engagement with, the inside face-sheet  42 . Illustrative, non-exclusive example of suitable sealers include (but are not limited to) room-temperature vulcanizing (RTV) silicone sealers. Illustrative, non-exclusive examples of gaskets include (but are not limited to) form-in-place gaskets and compression gaskets, including pre-cured RTV gaskets and graphite gaskets. In some embodiments, a pre-load may be placed on the gasket, which may facilitate secure and operative contact between a package  52  and the inside face-sheet  42  over the lifetime of a spacecraft  30 , including for up to 10 years, up to 15 years, or for greater than 15 years. 
     As discussed, a package  52  may include a heat pipe  40  of a heat pipe network  38  associated with a radiator panel  35 . As an illustrative, non-exclusive example with reference back to  FIG. 3 , the schematically represented vertical heat pipe  40  may be a package  52 , with the vertical heat pipe  40  being mounted to the side of the inside face-sheet  42  that faces toward the inside of the spacecraft  30  (that is, the internal side of the inside face-sheet  42 ), rather than being positioned between the inside face-sheet  42  and the outside face-sheet  44 . In such a configuration, other packages  52 , such as electronics equipment or other heat producing equipment, may conduct heat through the inside face-sheet  42  to the horizontally oriented heat pipes  40 , which in turn transfer the heat back through the inside face-sheet  42  to the vertically oriented heat pipe  40 , and ultimately to a region of the radiator panel  35  that radiates the heat to outer space during operation of the spacecraft  30 . Other configurations also are within the scope of the present disclosure, and the relative orientation of the heat pipes  40  in the described example is not limiting. 
     In  FIG. 4 , package  52  is schematically illustrated in dashed lines, schematically representing that the package may be considered a component of a radiator panel  35  or it may be considered a separate component that is coupled to a radiator panel  35 . 
     As schematically illustrated in  FIG. 4  in dashed lines, some radiator panels  35  may include an insert  48 , with such radiator panels  35  being referred to here as radiator panels  36 . In other words, radiator panels  36  are examples of radiator panels  35 , but radiator panels  35  are not required to include an insert  48 . Inserts  48 , when present, may take any suitable form and may be constructed of any suitable material. As illustrative, non-exclusive examples, an insert  48  may be constructed of a conductive material such as of aluminum, aluminum alloy, titanium, titanium alloy, or steel, including stainless steel. Non-conductive materials also may be used to construct an insert  48 , depending on the desired properties of the insert  48 . In some embodiments, the insert  48  may have a similar or identical thermal coefficient of expansion as one or more of the heat pipe(s)  40 , the inside face-sheet  42 , and/or the outside face-sheet  44 . Inserts  48  may be constructed utilizing a machining process, but other methods of producing inserts  48  also are within the scope of the present disclosure. 
     Inserts  48  are configured to be positioned between the inside face-sheet  42  and the outside face-sheet  44  of a radiator panel  36 , adjacent to a heat pipe  40 , to operatively secure a package  52  to the inside face-sheet  42 . Accordingly, in  FIG. 4 , insert  48  is illustrated in an overlapping relation with package  52 , schematically representing that at least a portion of an insert  48  may be positioned directly opposite at least a portion of a package  52 , relative to the inside face-sheet  42 . 
     As an illustrative, non-exclusive example, inserts  48  may be configured to operatively receive a fastener  56  for securing a package  52  to the inside face-sheet  42 . For example, the insert  48  may include a tapped bore for mating with a threaded fastener. Additionally or alternatively, the insert  48  may include a bore or other passage for receiving a fastener  56  and may be configured so that a nut or other structure may mate with the fastener  56 . Accordingly, assembly of a radiator panel  36  may require drilling, or otherwise machining, one or more holes through the inside face-sheet  42  for passage of one or more fasteners  56 . 
     In  FIG. 4 , a single fastener  56  is schematically illustrated as being associated with an insert  48 ; however, any suitable number of fasteners  56  and corresponding holes in the inside face-sheet  42  may be utilized, depending on the embodiment of radiator panel  36  and/or on the embodiment of insert  48  being used and/or depending on the configuration of package  52  being secured to the inside face-sheet  42 . 
     In  FIG. 4 , a single insert  48  is illustrated in dashed lines, and three additional inserts  48  are illustrated in dash-dot lines, schematically representing that any suitable number of inserts  48  may be used to operatively secure a package  52  to an inside face-sheet  42  of a radiator panel  36 . In some embodiments of a radiator panel  36 , it may be desirable to install inserts  48  in pairs, such as in positions directly opposite each other relative to a heat pipe  40 , as schematically illustrated in  FIG. 4 . It also is within the scope of the present disclosure, such as depending on the size of package  52  being secured to the inside face-sheet  42 , that more than one insert  48  may be installed in a spaced-apart relation to each other along the length of a heat pipe  40 , as optionally and schematically illustrated in  FIG. 4 . 
     In some embodiments, insert(s)  48  may not extend through an opening in the inside face-sheet  42 . Accordingly, methods of assembling radiator panels  36  may not require cutting the inside face-sheet  42  for passage of a portion of an insert  48 . Additionally or alternatively, a method of assembling a radiator panel  36  may not include extending a portion of an insert  48  through an opening in the inside face-sheet  42 . 
     In some embodiments, the core  50  may not need to be modified for securing a package  52  to an insert  48  and the inside face-sheet  42 . Additionally or alternatively, some methods of assembling a radiator panel  36  may not require core-stepping. 
       FIGS. 5-7  schematically represent illustrative, non-exclusive examples of various insert configurations that are within the scope of the present disclosure. For example, in  FIG. 5 , a plurality of similarly or identically configured inserts  48  are positioned in a spaced-apart relation to each other along opposite sides of a heat pipe  40 , with the extent of the inserts  48  generally corresponding to the footprint of a package  52 . In the example of  FIG. 5 , each insert  48  is associated with a single fastener  56 , but other configurations are within the scope of the present disclosure. In  FIG. 6 , rather than including more than one insert  48  on each side of heat pipe  40 , a pair of elongate inserts  48  are utilized with the extent of the two inserts  48  generally corresponding to the footprint of a package  52 . Moreover, in the example of  FIG. 6 , each insert  48  is associated with more than one fastener  56 , but other configurations also are within the scope of the present disclosure. In the example of  FIG. 7 , elongate inserts  48  are depicted, but with each insert  48  including a plurality of bodies  58  separated by a web  60 , and with each body  58  being associated with at least one fastener  56 . Other configurations of inserts  48  are within the scope of present disclosure, and the examples of  FIGS. 5-7  are not limiting. Moreover, a radiator panel  36  may include one or more of variously configured inserts  48 , and not all inserts  48  for a radiator panel  36  are required to have the same configuration. 
     Some embodiments of inserts  48  may be specifically configured to mate with, or otherwise be associated with, a specific configuration of a heat pipe  40 . For example, as discussed herein and with reference back to  FIG. 4 , an insert  48  may include (but is not required to include) one or more of a positioning structure  62  and/or a retaining structure  64  configured to position and/or retain the insert  48  relative to a heat pipe  40 . In some embodiments, an insert  48  may be operatively engaged and in thermal communication with one or more of the inside face-sheet  42 , the outside face-sheet  44 , and/or the heat pipe  40 . By ‘operatively engaged with,’ it is meant that an insert  48  may be in direct physical, or mechanical, contact with a heat pipe  40 , and that an insert  48  may be in indirect physical, or mechanical, communication with a heat pipe  40 , such as with a gasket or sealant positioned directly between the insert  48  and the heat pipe  40 . This operative engagement between an insert  48  and a heat pipe  40  is advantageous, because such a configuration resists joint relaxation and mechanical creep, thereby leading to an efficient and long-term transfer of heat from a package  52  to a heat pipe  40  and ultimately to outer space. 
     Additionally or alternatively, inserts  48  may be adhered, or sealed, to an adjacent heat pipe  40 . Additionally or alternatively, a gasket may be operatively positioned between and engaged with an insert  48  and a heat pipe  40 . Additionally or alternatively, one or both of an adhesive, or sealer, and/or a gasket may be used between an insert  48  and one or both of the inside face-sheet  42  and/or the outside face-sheet  44  of radiator panel  36 . Illustrative, non-exclusive examples of suitable sealers include (but are not limited to) room-temperature vulcanizing (RTV) silicone sealers and epoxy. Illustrative, non-exclusive examples of gaskets include (but are not limited to) form-in-place gaskets and compression gaskets, including pre-cured RTV gaskets and graphite gaskets. 
     Kits for assembling radiator panels  36  are within the scope of the present disclosure and may include a selection of the various components necessary to assemble a radiator panel  36 . For example, a kit may include one or more of each of an inside face-sheet  42 , an outside face-sheet  44 , a heat pipe  40 , and an insert  48 . In some kits, a plurality of inserts  48  may be provided. In some examples, inserts  48  of various dimensions, configurations, and/or sizes may be included within a kit, such as corresponding to (but not limited to) the examples of the schematic representations of  FIGS. 5-7 . Accordingly, suitable inserts  48  may be selected, such as based at least in part on correspondence to a particular configuration of package  52  being mounted to an inside face-sheet  42 . For example, although not required, one or more inserts  48  having a dimension corresponding to a dimension of a first package  52  may be selected to mount the first package  52  to an inside face-sheet  42 , and one or more inserts  48  having a dimension corresponding to a dimension of a second package  52  may be selected to mount the second package  52  to the inside face-sheet  42 . Additionally or alternatively, a plurality of inserts  48  may be selected to be spaced-apart along the dimension of a corresponding package  52 . Other configurations also are within the scope of the present disclosure, and a kit may include any number of variously configured inserts  48  for use in assembling a radiator panel  36 . 
     When a radiator panel  36  is assembled, the radiator panel may be less susceptible to mechanical creep than radiator panels according to the prior art. As discussed, no penetration of the inside face-sheet  42  with a heat pipe  40 , or associated flange of a heat pipe  40 , is required to assemble a radiator panel  36 . Moreover, in some embodiments, the inside face-sheet  42 , the insert  48 , and the body of the heat pipe  40  may be constructed of materials having similar or identical thermal coefficients of expansion. Moreover, a package  52  is secured to the inside face-sheet  42  by one or more inserts  48 . Moreover, the compression of optional gaskets between a package  52  and the inside face-sheet  42  may not be lost over the lifetime of a spacecraft  30  and associated radiator panel  36 . Moreover, the operative engagement between the insert(s)  48  and the heat pipe  40 , the operative engagement between the package  52  and the inside face-sheet  42 , and the fastening of the package  52  to the insert(s)  48  reduces the joint relaxation and mechanical creep that occurs with prior art radiator panels. These and other characteristics of radiator panels  36  may restrict, or resist, mechanical creep and may provide for a more efficient transfer of heat from a package  52  to a heat pipe  40  and ultimately to outer space than is possible with prior art radiator panels. 
     Additionally or alternatively, because a heat pipe  40  is not required to be modified, or otherwise customized, the design process for a radiator panel  36  for a spacecraft  30  is more efficient than otherwise possible with prior art radiator panels. For example, the design process for a radiator panel typically requires iterative steps, and sometimes several iterative steps, to appropriately position several packages  52  on an inside face-sheet  42 . Because heat pipes  40  do not have to be modified and because the heat pipes  40  do not penetrate the inside face-sheet  42 , the modification of heat pipes  40  and subsequent changes to the design do not require the scrapping of modified heat pipes and face-sheets that no longer correspond to the changed design. Other advantages and efficiencies also are experienced with the design and assembly of radiator panels  36  according to the present disclosure. 
     Turning now to  FIG. 8 , an illustrative, non-exclusive example of a radiator panel  36 , which optionally also may be a radiator panel  202 , is schematically illustrated in profile and is indicated generally at  100 . Where appropriate, the reference numerals from the schematic illustrations of  FIGS. 3-7  are used to designate corresponding parts of radiator panel  100 ; however, the example of  FIG. 8  is non-exclusive and does not limit the present disclosure to the illustrated embodiment. That is, neither radiator panels  36 , nor portions thereof, are limited to the specific embodiment of radiator panel  100  illustrated in  FIG. 8 , and radiator panels  36  may incorporate any number of the various aspects, configurations, characteristics, properties, etc. of radiator panels  36  or components thereof, including the schematically illustrated examples of  FIGS. 3-7 , and/or of radiator panel  100 , as well as variations thereof, without requiring the inclusion of all such aspects, configurations, characteristics, properties, etc. For the purpose of brevity, each previously discussed component, part, property, etc. or variants thereof may not be discussed again with respect to radiator panel  100  of  FIG. 8 ; however, it is within the scope of the present disclosure that the previously discussed features, variants, etc. may be utilized with radiator panel  100 . 
     Radiator panel  100  is illustrated together with, and may be described as including, a package  52 . The illustrated package  52  includes a body  102  and a pair of flanges  104  for receiving corresponding fasteners  56  for securing the package  52  to the inside face-sheet  42 . In the illustrated example, a gasket  106  is positioned between the package  52  and the inside face-sheet  42 ; however, as discussed herein, a sealer may additionally or alternatively be used, but neither a gasket  106  nor a sealer is required to all embodiments of radiator panels  36 . 
     The illustrative non-exclusive example of a heat pipe  40  utilized in radiator panel  100  is generally indicated at  108  and may be described as an off-the-shelf, unaltered heat pipe  40 . Heat pipe  108  includes a cylindrical core  110  and four generally planar extensions  112  extending from the cylindrical core  110 . Although not required, the cylindrical core  110  and the extensions  112  may be extruded as a single monolithic body. Extensions  112  include an inside extension  114 , an outside extension  116 , a left extension  118 , and a right extension  120 . The left and right extensions additionally or alternatively may be referred to as side extensions. 
     The inside extension  114  defines an inside planar surface  122  that faces away from the cylindrical core  110  and that operatively engages and is in thermal communication with the inside face-sheet  42 . The outside extension  116  defines an outside planar surface  124  that faces away from the cylindrical core  110 , that is parallel to the inside planar surface  122 , and that operatively engages and is in thermal communication with the outside face-sheet  44 . The left extension  118  defines a left planar surface  126  that faces away from the cylindrical core  110  and that engages and is in thermal communication with the left insert  48 . The right extension  120  defines a right planar surface  128  that faces away from the cylindrical core, that is parallel to the left planar surface  126 , and that operatively engages and is in thermal communication with the right insert  48 . 
     In dashed lines in  FIG. 8 , the inserts  48  are both illustrated as including optional positioning structure  62  and optional retaining structure  64  extending from the body  130  of the inserts  48 . The optional positioning structures  62  of the inserts  48  of radiator panel  100  include structure that is configured to engage and appropriately position the body  130  of the inserts  48  relative to the respective planar surfaces of the side extensions of the heat pipe  108 . More specifically, the optional positioning structures  62  of radiator panel  100  are in the form of a projection having a lip that wraps around the lower edge of the respective side extension of the heat pipe  108 . The optional retaining structures  64  of the inserts  48  of radiator panel  100  include structure that is configured to operatively retain the body  130  of the inserts  48  into operative engagement with the respective planar surfaces of the side extensions. The optional retaining structures  64  illustrated in the example of  FIG. 8  may be described as clips  64 , or as spring clips  64 . As discussed herein, an insert  48  may include neither of or one or both of the optional positioning structure  62  and the optional retaining structure  64 . 
     Inserts  48  of radiator panel  100  are configured to receive fasteners  56 . As discussed herein, it is within the scope of the present disclosure that inserts  48  may include tapped bores for appropriate mating with fasteners  56 . Additionally or alternatively, as illustrated in dashed-dot lines in  FIG. 8 , inserts  48  may be configured to accommodate a nut  132  for appropriate mating with fasteners  56 . As discussed, other configurations of inserts  48  and fasteners  56  are within the scope of the present disclosure. 
     Referring back to  FIG. 4 , and as mentioned,  FIG. 4  also schematically represents radiator panels  202  according to the present disclosure. Radiator panels  202  are examples of radiator panels  35  that include one or more optional external structural reinforcement members  200 . In other words, radiator panels  202  are examples of radiator panels  35 , but radiator panels  35  are not required to include an external structural reinforcement member  200 . Moreover, radiator panels  202  also may (but are not required to) be radiator panels  36  according to the present disclosure, such as including optional inserts  48  associated with radiator panels  36 . That is radiator panels  36  and radiator panels  202  are not necessarily, but may be, mutually exclusive. 
     When present, an external structural reinforcement member  200  may take any suitable form and may be constructed of any suitable material. Illustrative, non-exclusive examples of suitable materials include (but are not limited to) aluminum alloys, aluminum-beryllium alloy, aluminum 6061-T6, and other metallic and non-metallic materials having desired properties. 
     External structural reinforcement members  200  define an outer surface  204  that generally faces away from the outside face-sheet  44 . In some embodiments, the outer surface  204  is shaped to restrict reflection of light that is incident on the outer surface  204  onto the outside face-sheet  44 . In other words, an external structural reinforcement member  200 , and more specifically its outer surface  204 , may be configured to reflect incident light away from portions of the outside face-sheet  44  that are not obstructed by the external structural reinforcement member(s)  200 . In some embodiments, the external structural reinforcement members  200  may be described as being configured so as to not create any, or at least to minimize the creation of, light traps that may result in unwanted radiation of solar energy to the radiator panel  202 . Such configurations may be beneficial, so that the efficiency, or productiveness, of the radiator panel  202  is not compromised, and in some embodiments is perhaps even improved over radiator panels without external structural reinforcement members  200 . 
     In embodiments that include a plurality of external structural reinforcement members  200 , the spacing between adjacent external structural reinforcement members  200  may facilitate the restriction of reflection of light incident on the outer surface  204  of the external structural reinforcement members  200  onto the outside face-sheet  44 . That is, the spacing of the optional external structural reinforcement members  200  may be selected so that no light traps are created that otherwise may result in the heating of the radiator panel  202 , as opposed to the radiator panel  202  radiating heat away from the radiator panel  202 . 
     In some embodiments, one or both of the position of the outer surface(s)  204  and/or the spacing of a plurality of external structural reinforcement members  200  may reflect at least 30%, at least 40%, at least 50%, at least 60%, at least 70%, at least 80%, at least 90%, 30%-90%, 30%-70%, 30%-50%, 50%-90%, 50%-70%, or 70%-90% of all incident light on the outer surface(s)  204  away from the outside face-sheet  44 . 
     To achieve the desired reflection of light away from the outside face-sheet  44 , the outer surface  204  of one or more external structural reinforcement members  200  may include one or more planar surfaces and/or one or more curved, or arcuate, surfaces. Any suitable configuration of outer surfaces  204  may be used to achieve a desired or optimized configuration with respect to the reflection of light away from the outside face-sheet  44 . 
     In some embodiments, the outer surface  204  of an external structural reinforcement member  200  may have a mirrored finish  210 . In some embodiments, the mirrored finish  210  may be defined by one or more discrete mirror structures that are operatively coupled to a body of the external structural reinforcement member  200 . As illustrative, non-exclusive examples, mirror structures may include quartz mirrors having a thickness of approximately 2 mils (0.05 mm) adhered to the body of the external structural reinforcement member  200  with an RTV silicone sealer. Other configurations also are within the scope of the present disclosure, including mirrors constructed of different materials, mirrors having a thickness greater than or less than the thickness disclosed herein, as well as external structural reinforcement members  200  having bodies with a mirrored outer surface  54  without the inclusion of a separate mirror structure. Additionally or alternatively, the outer surface  204  of an external structural reinforcement member  200  may have a thermal coating, such as a high emissivity paint. 
     The number of, the configuration of, and/or the positioning of optional external structural reinforcement members  200  of radiator panels  202  may be selected to define a desired or predetermined natural frequency for the radiator panel  202 . As illustrative, non-exclusive examples, a radiator panel  202  may be designed to have, and may have, a natural frequency of approximately 20-50, 30-50, 40-50, 20-40, 30-40, 20-30, 20, 25, 30, 35, 40, 45, or 50 hertz. 
     Additionally or alternatively, the number of, the configuration of, and/or the positioning of optional external structural reinforcement members  200  of radiator panels  202  may be selected to define a stiffness of the radiator panel  202  corresponding to a desired, or predetermined, thickness, or depth,  206  of the radiator panel  202 , with the thickness  206  being defined as the distance from the external surface of the outside face-sheet  44  to the internal surface of the inside face-sheet  42 , as schematically indicated in  FIG. 4 . In such embodiments, the thickness  206  may correspond to the size of a heat pipe  40  positioned between the face-sheets  42 ,  44 . Moreover, the thickness  206  may be less than the thickness of a comparably stiff and sized radiator panel that does not include one or more external structural reinforcement members  200 . As an illustrative, non-exclusive example, a radiator panel  202  according to the present disclosure may have a natural frequency of approximately 35 hertz and may have panel thickness that is less than the thickness of a radiator panel that does not include any external structural reinforcement members  200  but that has a natural frequency of approximately 35 hertz. The thickness  206  of a radiator panel  202  may be less than 90%, 80%, 70%, 60%, 50%, 40%, or 30% of the thickness of a comparably stiff and sized radiator panel that does not include any external structural reinforcement members  200 . By comparably sized, it is meant that a comparable radiator panel has approximately the same width and height, but not necessarily the same thickness, and includes similar configurations of packages  52  and associated structures of the radiator panel  202  to which it is being compared. 
     Additionally or alternatively, the thickness  206  of a radiator panel  202  may be selected based on the size of one or more heat pipes  40  required to result in a desired, or predetermined, heat transfer rate of the radiator panel  202 . Stated differently, one or more heat pipes  40  may be sized to have a predetermined heat transfer rate that is not significantly greater that a requisite heat transfer rate for the radiator panel  202 , such as based in part on the heat produced by packages  52  and requiring radiation away from a spacecraft  30 . As illustrative, non-exclusive examples, a size of heat pipe(s)  40  may be selected so that the heat transfer rate associated with the heat pipe(s)  40  is no more than 100%, 110%, 120%, 130%, 140%, 150%, 160%, 170%, 180%, 190%, or 200% of the requisite heat transfer rate for the radiator panel  202 . Accordingly, a radiator panel  202  may include heat pipes  40  that are smaller than heat pipes  40  associated with a comparably stiff and sized radiator panel that does not include any external structural reinforcement members  200 . Stated differently, the size of heat pipes  40  to be used with a radiator panel  202  may be selected based on their heat transfer properties alone and without consideration of the stiffness of the heat pipes  40  as associated with the ultimate stiffness of the radiator panel  202 . In other words, radiator panels  202  do not require over-sized heat pipes  40  in order to produce a radiator panel with a desired, or predetermined, stiffness. In contrast, prior art radiator panels do require over-sizing heat pipes in order to produce a radiator panel with a desired, or predetermined, stiffness. 
     Additionally or alternatively, a radiator panel  202  may have a mass that is less than the mass of a comparably stiff radiator panel that does not include any external structural reinforcement members  200 . As illustrative, non-exclusive examples, a radiator panel  202  may have a mass that is at least 5%, 10%, 15%, 20%, 25%, or 30% less than the mass of a comparably stiff and sized radiator panel. 
     Additionally or alternatively, a radiator panel  202  may be free of internal structural reinforcement members that are coupled to the inside face-sheet  42 , such as corresponding to an internal stiffening member  19  discussed with reference to  FIG. 1  and prior-art radiator panels  10 . In some such embodiments, the radiator panel  202  may have a stiffness that is at least approximately equal to a comparably stiff and sized radiator panel that does not include an external structural reinforcement member  200  but that does include an internal structural reinforcement member. In some such embodiments, the mass of the radiator panel  202  may be less than the mass of a comparably stiff and sized radiator panel that does not include an external structural reinforcement member  200  but that does include an internal structural reinforcement member. In some such examples, the mass of the radiator panel  202  may be at least 5%, 10%, 15%, 20%, 25%, or 30% less than the mass of the comparably stiff and sized radiator panel. 
     In some embodiments, an external structural reinforcement member  200  may be adhered to the outside face-sheet  44 , such as with an RTV silicone sealer or any other suitable adhesive. Additionally or alternatively, as optionally and schematically illustrated in  FIG. 4 , one or more fasteners  208  may be utilized to operatively couple an external structural reinforcement member  200  to the outside face-sheet  44  of a radiator panel  202 . 
     In  FIG. 4 , an external structural reinforcement member  200  is schematically illustrated in an overlapping relation to heat pipe  40 , schematically representing that external structural reinforcement members  200  may or may not be positioned above one or more heat pipes  40  that are positioned between the face-sheets  42 ,  44  of the radiator panel  202 . 
     Kits for assembling radiator panels  202  are within the scope of the present disclosure and may include a selection of the various components necessary to assembly a radiator panel  202 . For example, a kit may include one or more of each of an inside face-sheet  42 , an outside face-sheet  44 , a heat pipe  40 , a core  50 , and an external structural reinforcement member  200 . 
     Turning now to  FIGS. 9-10 , a portion of an illustrative, non-exclusive example of a radiator panel  202 , which optionally also may be a radiator panel  36 , is illustrated and is indicated generally at  300 . Where appropriate, the reference numerals from the schematic illustrated of  FIGS. 3-4  are used to designate corresponding parts of radiator panel  300 ; however, the example of  FIGS. 9-10  is non-exclusive and does not limit the present disclosure to the illustrated embodiment (or variations thereon). That is, neither radiator panels  202 , nor portions thereof, are limited to the specific embodiment of radiator panel  300  (or variations thereon) illustrated in  FIGS. 9-10 , and radiator panels  202  may incorporate any number of the components thereof, including the schematically illustrated examples of  FIGS. 3-4 , and/or of radiator panel  300 , as well as variations thereof, without requiring the inclusion of all such aspects, configurations, characteristics, properties, etc. For the purpose of brevity, each previously discussed component, part, property, etc. or variants thereof may not be discussed again with respect to radiator panel  300  of  FIGS. 9-10 ; however, it is within the scope of the present disclosure that the previously discussed features, variants, etc. may be utilized with radiator panel  300 . 
     Referring first to  FIG. 9 , radiator panel  300  includes a pair of side frame members  302  that define parallel and lateral sides of the radiator panel  300 . Additionally or alternatively, the side frame members  302  may be described as a component of a spacecraft  30 , to which a radiator panel  300  is operatively coupled. In the illustrated example of radiator panel  300 , the external structural reinforcement member  200  spans the radiator panel  300  between the side frame members  302 . That is, the external structural reinforcement member  200  spans the entire width of the radiator panel  300 ; however, as discussed herein, such a configuration is not required to all embodiments of radiator panels  202 . 
     As seen in  FIG. 9 , radiator panel  300  is an example of a radiator panel  202  that utilizes fasteners  208  to operatively couple the external structural reinforcement member  200  to the outside face-sheet  44 . Moreover, the external structural reinforcement member  200  of radiator panel  300  is operatively coupled to the side frame members  302 . 
     The external structural reinforcement member  200  of radiator panel  300  includes a pair of flanges  304  and a body  306  that interconnects the flanges  304 . The flanges  304  are operatively coupled to the outside face-sheet  44  by a plurality of fasteners  208 . 
     The outer surface  204  of the external structural reinforcement member  200  of radiator panel  300  is an example of an outer surface that includes at least two planar surfaces. In the illustrated example, the external structural reinforcement member  200  includes five planar surfaces with the flanges  304  defining two of the planar surfaces and the body  306  defining three of the planar surfaces. As illustrated, the body  306  of the external structural reinforcement member  200  defines a void  310  between the body  306  and the outside face-sheet  44 , and in the illustrated example, the void  310  has a perpendicular cross-sectional profile that is trapezoidal. Other shapes also are within the scope of the present disclosure including voids  310  having other quadrilateral shapes, and voids  310  having perpendicular cross-sectional profiles that are triangular, semi-circular, semi-ovular, or variations thereon. Illustrative, non-exclusive examples of such other optionally shaped external structural reinforcement members  200  are illustrated in dash-dot and dash-dot-dot lines in  FIG. 10 . 
     In the example illustrated in  FIG. 9  and in solid lines in  FIG. 10 , the planar surfaces of the outer surface  204  of the body  306  are angled greater than 180 degrees relative to each other. The planar surfaces of the outer surface of the flanges  304  are angled between 90 and 180 degrees relative to the adjacent planar surfaces of the body  306 . Other angular configurations of the planar surfaces of outer surface  204  are within the scope of the present disclosure, including planar surfaces that are angled between 270 and 360 degrees relative to each other. Moreover, as illustrated in dash-dot lines in  FIG. 10 , some outer surface  204  of a body  306  may not include any planar surfaces and instead may include a curved, or arcuate, surface. 
     In the illustrative, non-exclusive example of radiator panel  300 , the outer surface  204  includes a first planar surface  312  that is angled approximately 120 degrees relative to the outside face-sheet  44 , a second planar surface  314  that is angled approximately 210 degrees relative to the first surface  312  and that is parallel to the outside face-sheet  44 , and a third surface  316  that is angled approximately 210 degrees relative to the second surface  314  and approximately 120 degrees relative to the outside face-sheet  44 . 
     As discussed herein, external structural reinforcement members  200  may include mirror structures that are adhered to or otherwise operatively coupled to the body  306  of the external structural reinforcement member  200 . In  FIG. 10 , this optional mirror structure is schematically illustrated in dashed lines at  318 . 
     Illustrative, non-exclusive examples of inventive subject matter according to the present disclosure are described in the following enumerated paragraphs: 
     A. A radiator panel for a spacecraft, the radiator panel comprising: 
     two spaced-apart face-sheets including an inside face-sheet and an outside face-sheet; 
     a heat pipe positioned between the two spaced-apart face-sheets and operatively engaged and in thermal communication with the two spaced-apart face-sheets; and 
     an insert positioned adjacent to the heat pipe (and optionally operatively engaged with the heat pipe), wherein the insert is configured with at least one feature useful in the operative securing of (and optionally to operatively secure) a package to the inside face-sheet opposite the heat pipe and the insert so that heat from the package may operatively conduct from the package through the inside face-sheet to the heat pipe. 
     A1. The radiator panel of paragraph A, wherein the insert is configured to operatively receive a fastener for securing the package to the inside face-sheet. 
     A2. The radiator panel of any of paragraphs A-A1, wherein the heat pipe is positioned completely between the two spaced-apart face-sheets. 
     A3. The radiator panel of any of paragraphs A-A2, wherein the heat pipe does not extend through, or penetrate, the inside face-sheet and/or does not extend through, or penetrate, the outside face-sheet. 
     A4. The radiator panel of any of paragraphs A-A3, wherein the insert is positioned between, and optionally completely between, the two spaced-apart face-sheets. 
     A5. The radiator panel of any of paragraphs A-A4, wherein the insert does not extend through, or penetrate, the inside face-sheet and does not extend through, or penetrate, the outside face-sheet. 
     A6. The radiator panel of any of paragraphs A-A5, wherein the insert is structurally a separate part from the heat pipe. 
     A7. The radiator panel of any of paragraphs A-A6, further comprising: 
     the package, wherein the package is secured to the inside face-sheet opposite the heat pipe. 
     A7.1. The radiator panel of paragraph A7, further comprising: 
     a gasket positioned between the inside face-sheet and the package. 
     A7.2. The radiator panel of any of paragraphs A7-A7.1, further comprising: 
     one or more fasteners that operatively secure the package to the inside face-sheet. 
     A7.3. The radiator panel of any of paragraphs A7-A7.2, wherein the package includes electronic equipment. 
     A7.4. The radiator panel of any of paragraphs A7-A7.3, wherein the heat pipe is a first heat pipe, and wherein the package includes a second heat pipe positioned transverse to the first heat pipe. 
     A8. The radiator panel of any of paragraphs A-A7.4, wherein the heat pipe is an off-the-shelf heat pipe. 
     A8.1. The radiator panel of paragraph A8, wherein the heat pipe is not modified from its off-the shelf configuration. 
     A9. The radiator panel of any of paragraphs A-A8.1, wherein the heat pipe is not customized for the radiator panel. 
     A10. The radiator panel of any of paragraphs A-A9, wherein the heat pipe includes: 
     a cylindrical core; and 
     an inside extension extending from the cylindrical core, wherein the inside extension defines an inside planar surface that faces away from the cylindrical core, and wherein the inside planar surface operatively engages and is in thermal communication with the inside face-sheet. 
     A10.1. The radiator panel of paragraph A10, wherein the heat pipe further includes: 
     an outside extension extending from the cylindrical core, wherein the outside extension defines an outside planar surface that faces away from the cylindrical core and that is generally parallel to the inside planar surface, and wherein the outside planar surface operatively engages and is in thermal communication with the outside face-sheet. 
     A10.2. The radiator panel of any of paragraphs A10-A10.1, wherein the heat pipe further includes: 
     a left extension extending from the cylindrical core, wherein the left extension defines a left planar surface that faces away from the cylindrical core, and optionally wherein the left planar surface operatively engages and is in thermal communication with the insert. 
     A10.2.1. The radiator panel of paragraph A10.2, wherein the insert includes a body and a positioning structure extending from the body, wherein the positioning structure operatively engages the left extension and operatively positions the body relative to and into operative engagement with the left planar surface. 
     A10.2.2. The radiator panel of any of paragraph A10.2-A10.2.1, wherein the insert includes a body and a retaining structure extending from the body, wherein the retaining structure operatively retains the body to the left extension and the body into operative engagement with the left planar surface. 
     A10.2.3. The radiator panel of any of paragraphs A10.2-A10.2.2, wherein the heat pipe further includes: 
     a right extension extending from the cylindrical core, wherein the right extension defines a right planar surface that faces away from the cylindrical core and that is generally parallel to the left planar surface. 
     A10.2.3.1. The radiator panel of paragraph A10.2.3, wherein the insert is a first insert and the radiator panel further comprises: 
     a second insert positioned adjacent to the heat pipe generally opposite the first insert, wherein the second insert is configured to operatively secure the package to the inside face-sheet opposite the heat pipe, the first insert, and the second insert; and 
     a second insert positioned adjacent to the heat pipe generally opposite the first insert, wherein the second insert is configured to operatively secure the package to the inside face-sheet opposite the heat pipe, the first insert, and the second insert; and 
     optionally wherein the right planar surface operatively engages and is in thermal communication with the second insert. 
     A10.2.3.1.1. The radiator panel of paragraph A10.2.3.1, wherein the second insert includes a body and a positioning structure extending from the body of the second insert, wherein the positioning structure of the second insert operatively engages the right extension and operatively positions the body of the second insert relative to and into operative engagement with the right planar surface. 
     A10.2.3.1.2. The radiator panel of any of paragraph A10.2.3.1-A10.2.3.1.1, wherein the second insert includes a body and a retaining structure extending from the body of the second insert, wherein the retaining structure of the second insert operatively retains the body of the second insert to the right extension and the body of the second insert into operative engagement with the right planar surface. 
     A11. The radiator panel of any of paragraphs A-A10.2.3.1.2, wherein the heat pipe includes an extruded heat pipe body. 
     A11.1. The radiator panel of paragraph A11 (when depending from any of paragraphs A10-A10.2.3.1.2), wherein the heat pipe body includes the cylindrical core and one or more of the respective recited extensions of paragraphs A10-A10.2.3.1.2. 
     A12. The radiator panel of any of paragraphs A-A11.1, further comprising: 
     honeycomb structure positioned between the two spaced-apart face-sheets. 
     A13. The radiator panel of any of paragraphs A-A12, further comprising: 
     corrugated structure positioned between the two spaced-apart face-sheets. 
     A14. The radiator panel of any of paragraphs A-A13, wherein the outside face-sheet includes a mirrored outside surface for radiating heat away from the spacecraft. 
     A15. The radiator panel of any of paragraphs A-A14, wherein the outside face-sheet is not penetrated for securement of the package to the inside face-sheet. 
     A16. The radiator panel of any of paragraphs A-A15, wherein the insert is operatively engaged with the heat pipe. 
     A16.1. The radiator panel of paragraph A16, wherein the operative engagement between the insert and the heat pipe prevents mechanical creep of the heat pipe during the lifetime of the spacecraft (optionally, including for up to 10 or more years). 
     A17. The radiator panel of any of paragraphs A-A16.1, wherein the insert includes a plurality of inserts corresponding to a footprint associated with the package. 
     A18. The radiator panel of any of paragraphs A-A17, wherein the insert is a first insert and the radiator panel further comprises a second insert positioned adjacent to the heat pipe generally opposite the first insert, wherein the second insert is configured with at least one feature useful in the operative securing of the package to the inside face-sheet opposite the heat pipe from the second insert. 
     A19. The radiator panel of any of paragraphs A-A18, wherein the insert further includes a cylindrical core and an extension extending from the cylindrical core, wherein the extension defines a substantially planar extension surface that faces away from the cylindrical core, and wherein the insert includes a substantially planar insert surface operatively engaged and in thermal communication with the substantially planar extension surface. 
     A20. A spacecraft including the radiator panel of any of paragraphs A-A19. 
     B. An insert for securing a package to a radiator panel of a spacecraft, wherein the radiator panel includes two spaced-apart face-sheets including an inside face-sheet and an outside face-sheet, and a heat pipe positioned between the two spaced-apart face-sheets, the insert comprising: 
     a body configured to be positioned between the two spaced-apart face-sheets and adjacent to the heat pipe (and optionally operatively engaged with the heat pipe) and to operatively secure the package to the inside face-sheet opposite the heat pipe and the insert so that heat from the package may operatively conduct from the package through the inside face-sheet to the heat pipe. 
     B1. The insert of paragraph B, wherein the insert is configured to mate with a heat pipe that includes a cylindrical core and an extension extending from the cylindrical core, wherein the extension defines a planar surface that faces away from the cylindrical core, and wherein the insert is configured to mate with the extension. 
     B1.1. The insert of paragraph B1, further comprising: 
     a positioning structure extending from the body, wherein the positioning structure is configured to operatively engage the extension for operative positioning of the body relative to and into operative engagement with the planar surface. 
     B1.2. The insert of any of paragraphs B1-B1.1, further comprising: 
     a retaining structure extending from the body, wherein the retaining structure is configured to operatively retain the body to the extension and the body into operative engagement with the planar surface. 
     B2. The insert of any of paragraphs B-B1.2, wherein the body is configured to operatively receive a fastener for securing the package to the inside face-sheet. 
     B3. A plurality of inserts according to any of paragraphs B-B2. 
     B3.1. The plurality of inserts of paragraph B3, comprising: 
     a first insert having a first width; and 
     a second insert having a second width that is greater than the first width. 
     C. A kit for assembling a radiator panel for a spacecraft, the kit comprising: 
     an inside face-sheet; 
     an outside face-sheet; 
     one or more heat pipes for being positioned between the inside face-sheet and the outside face-sheet; and 
     a plurality of inserts, wherein each insert is configured to be positioned adjacent to a heat pipe (and optionally operatively engaged with the heat pipe) between the inside face-sheet and the outside face-sheet, and wherein each insert is configured to operatively secure a package to the inside face-sheet opposite the heat pipe. 
     C1. The kit of paragraph C, wherein the plurality of inserts includes a first subset of inserts having a first width and a second subset of inserts having a second width that is greater than the first width. 
     C2. The kit of any of paragraphs C-C1, wherein the inside face-sheet, the outside face-sheet, the one or more heat pipes, and the plurality of inserts are configured to be assembled selectively into an assembled configuration of the radiator panel, wherein in the assembled configuration, the heat pipe does not extend through an opening in the inside face-sheet and the plurality of inserts do not extend through bores in the inside face-sheet. 
     C3. The kit of any of paragraphs C-C2, further comprising the subject matter of any of paragraphs A-B3.1. 
     D. A method of assembling a radiator panel for a spacecraft, the method comprising: 
     positioning an insert adjacent to a heat pipe (and optionally in operative engagement with the heat pipe); 
     positioning an inside face-sheet and an outside face-sheet on opposed sides of the insert and the heat pipe; 
     positioning a package operatively on the inside face-sheet opposite the heat pipe so that heat from the package may operatively conduct from the package through the inside face-sheet to the heat pipe; and 
     securing the package to the inside face-sheet and the insert. 
     D1. The method of paragraph D, wherein the insert, the heat pipe, the inside face-sheet, the outside face-sheet, and the package include the corresponding subject matter of any of paragraphs A-B3.1. 
     D2. The method of any of paragraphs D-D1, wherein the method does not include alteration of the heat pipe. 
     D3. The method of any of paragraphs D-D2, wherein the method does not include cutting the inside face-sheet for passage of a flange associated with a heat pipe. 
     D4. The method of any of paragraphs D-D3, wherein the method does not include extending a portion of the heat pipe through an opening in the inside face-sheet. 
     D5. The method of any of paragraphs D-D4, wherein the securing does not include penetrating the outside face-sheet. 
     D6. The method of any of paragraphs D-D5, wherein the insert is a first insert, the method further comprising: 
     positioning a second insert adjacent to the heat pipe (and optionally in operative engagement with the heat pipe) generally opposite the first insert; 
     wherein the securing includes securing the package to the second insert. 
     D7. The method of any of paragraphs D-D6, wherein the method does not include modifying a corrugated or honeycomb core associated with the radiator panel. 
     D8. The method of any of paragraphs D-D7, wherein the method results in a radiator panel according to any of paragraphs A-A19. 
     E. A radiator panel for a spacecraft, the radiator panel comprising: 
     two spaced-apart face-sheets including an inside face-sheet and an outside face-sheet; 
     a core positioned between the two spaced-apart face-sheets; and 
     at least one external structural reinforcement member extending across an external side of the outside face-sheet. 
     E1. The radiator panel of paragraph E, further comprising: 
     at least one heat pipe positioned between the two spaced-apart face-sheets and operatively engaged and in thermal communication with the two spaced-apart face-sheets. 
     E1.1 The radiator panel of paragraph E1, wherein the heat pipe is sized to have a predetermined heat transfer rate associated with the radiator panel, wherein the predetermined heat transfer rate is no more than 100%, 110%, 120%, 130%, 140%, 150%, 160%, 170%, 180%, 190%, or 200% of a requisite heat transfer rate for the radiator panel. 
     E2. The radiator panel of any of paragraphs E-E1.1, wherein the core includes a honeycomb core. 
     E3. The radiator panel of any of paragraphs E-E2, wherein the radiator panel has a width and a height, and wherein the at least one external structural reinforcement member substantially spans the width of the radiator panel. 
     E4. The radiator panel of any of paragraphs E-E3, wherein the at least one structural reinforcement member includes a plurality of spaced-apart structural reinforcement members. 
     E5. The radiator panel of any of paragraphs E-E4, wherein the at least one external structural reinforcement member defines an outer surface that generally faces away from the outside face-sheet. 
     E5.1. The radiator panel of paragraph E5, wherein the outer surface is shaped to restrict reflection of light incident on the outer surface onto the outside face-sheet. 
     E5.1.1. The radiator panel of paragraph E5.1, wherein the at least one external structural reinforcement member includes a plurality of spaced-apart external structural reinforcement members, and wherein a spacing between adjacent external structural reinforcement members restricts reflection of light incident on the outer surface of the external structural reinforcement members onto the outside face-sheet. 
     E5.2. The radiator panel of any of paragraphs E5-E5.1.1, wherein the outer surface is configured to reflect at least 30%, at least 40%, at least 50%, at least 60%, at least 70%, at least 80%, at least 90%, 30%-90%, 30%-70%, 30%-50%, 50%-90%, 50%-70%, or 70%-90% of all incident light on the outer surface away from the outside face-sheet. 
     E5.3. The radiator panel of any of paragraphs E5-E5.2, wherein the outer surface includes at least two planar surfaces. 
     E5.4. The radiator panel of any of paragraphs E5-E5.3, wherein the outer surface includes at least two planar surfaces that are angled greater than 180 degrees relative to each other. 
     E5.5. The radiator panel of any of paragraphs E5-E5.4, wherein the outer surface includes at least two planar surfaces that are angled between 90 and 180 degrees relative to each other. 
     E5.6. The radiator panel of any of paragraphs E5-E5.5, wherein the outer surface includes at least two planar surfaces that are angled between 270 and 360 degrees relative to each other. 
     E5.7. The radiator panel of any of paragraphs E5-E5.6, wherein the outer surface includes a first surface that is angled (or approximately angled) 120 degrees relative to the outside face-sheet, a second surface that is angled (or approximately angled) 210 degrees relative to the first surface and that is parallel (or approximately parallel) to the outside face-sheet, and a third surface that is angled (or approximately angled) 210 degrees relative to the second surface and 120 degrees relative to the outside face-sheet. 
     E5.8. The radiator panel of any of paragraphs E5-E5.7, wherein the outer surface includes at least one arcuate (or curved) surface. 
     E5.9. The radiator panel of any of paragraphs E5-E5.8, wherein the outer surface includes a mirrored finish. 
     E6. The radiator panel of any of paragraphs E-E5.9, wherein the at least one external structural reinforcement member defines a void between the at least one external structural reinforcement member and the outside face-sheet. 
     E6.1. The radiator panel of paragraph E6, wherein a perpendicular cross-sectional profile of the void is a trapezoid. 
     E6.2. The radiator panel of paragraph E6, wherein a perpendicular cross-sectional profile of the void is a quadrilateral. 
     E6.3. The radiator panel of paragraph E6, wherein a perpendicular cross-sectional profile of the void is a semi-circle or semi-oval or substantially similar to a semi-circle or semi-oval. 
     E6.4. The radiator panel of paragraph E6, wherein a perpendicular cross-sectional profile of the void is a triangle. 
     E7. The radiator panel of any of paragraphs E-E6.4, wherein the at least one external structural reinforcement member includes a pair of flanges coupled to the outside face-sheet and a body that interconnects the flanges. 
     E7.1. The radiator panel of paragraph E7, wherein the at least one external structural reinforcement member defines an outer surface that generally faces away from the outside face-sheet, and wherein the pair of flanges defines a portion of the outer surface. 
     E7.2. The radiator panel of any of paragraphs E7-E7.1, wherein the pair of flanges is adhered to the outside-face sheet. 
     E7.3. The radiator panel of any of paragraphs E7-E7.2, further comprising: 
     a plurality of fasteners extending through the pair of flanges, through the outside face-sheet, and into the core. 
     E8. The radiator panel of any of paragraphs E-E7.3, wherein the radiator panel has a natural frequency of approximately 20-50, 30-50, 40-50, 20-40, 30-40, 20-30, 20, 25, 30, 35, 40, 45, or 50 hertz. 
     E9. The radiator panel of any of paragraphs E-E8, wherein the two spaced-apart face-sheets define a panel depth (or thickness) between the two spaced-apart face-sheets, wherein the radiator panel defines a panel stiffness that is at least approximately equal to a stiffness of a comparably stiff and sized radiator panel that does not include an external structural reinforcement member, and wherein the panel depth is less than a depth (or thickness) of the comparably stiff and sized radiator panel. 
     E9.1. The radiator panel of paragraph E9, wherein the panel depth is less than 90%, 80%, 70%, 60%, 50%, 40%, or 30% of the depth of the comparably stiff and sized radiator panel. 
     E10. The radiator panel of any of paragraphs E-E9.1, wherein the radiator panel has a panel mass, wherein the radiator panel defines a panel stiffness that is at least approximately equal to a stiffness of a comparably stiff and sized radiator panel that does not include an external structural reinforcement member, and wherein the panel mass is less than a mass of the comparably stiff and sized radiator panel. 
     E10.1. The radiator panel of paragraph E10, wherein the panel mass is at least 5%, 10%, 15%, 20%, 25%, or 30% less than the mass of the comparably stiff and sized radiator panel. 
     E11. The radiator panel of any of paragraphs E-E10.1, wherein the radiator panel is free of internal structural reinforcement members coupled to the inside face-sheet, and wherein the radiator panel defines a panel stiffness. 
     E11.1. The radiator panel of paragraph E11, wherein the panel stiffness is at least approximately equal to a stiffness of a comparably stiff and sized radiator panel that does not include an external structural reinforcement member and that does include at least one internal structural reinforcement member. 
     E11.2. The radiator panel of any of paragraphs E11-E11.1, wherein the radiator panel has a panel mass, wherein the panel stiffness is at least approximately equal to a stiffness of a comparably stiff and sized radiator panel that does not include an external structural reinforcement member and that does include at least one internal structural reinforcement member, and wherein the panel mass is at least 5%, 10%, 15%, 20%, 25%, or 30% less than the mass of the comparably stiff and sized radiator panel. 
     E12. The radiator panel of any of paragraphs E-E11.2, further comprising: 
     a pair of side frame members defining parallel and lateral edges of the radiator panel, wherein the at least one external structural reinforcement member spans the radiator panel between the pair of side frame members. 
     E12.1. The radiator panel of paragraph E12, wherein the at least one external radiator panel is operatively coupled to the pair of side frame members. 
     E13. The radiator panel of any of paragraphs E-E12.1, wherein the at least one external structural reinforcement member includes a plurality of spaced-apart and parallel external structural reinforcement members. 
     E14. The radiator panel of any of paragraphs E-E13, further comprising the subject matter of any of paragraphs A-A20. 
     F. An external structural reinforcement member for stiffening a radiator panel of a spacecraft, the external structural reinforcement member comprising: 
     a body configured to be operatively coupled to and extend across an outside face-sheet of the radiator panel. 
     F1. The external structural reinforcement member of paragraph F, further comprising the subject matter associated with the external structural reinforcement member of any of paragraphs E-E14. 
     G. A kit for assembling a radiator panel for a spacecraft, the kit comprising: 
     an inside face-sheet; 
     an outside face-sheet; 
     a core for being positioned between the inside face-sheet and the outside face-sheet; 
     at least one heat pipe for being positioned between the inside face-sheet and the outside face-sheet; and 
     at least one external structural reinforcement member configured to be operatively coupled to the outside face-sheet for structurally stiffening the radiator panel. 
     G1. The kit of paragraph G, further comprising the subject matter of any of paragraphs A-C3 and E-E14. 
     H. A method of assembling a radiator panel for a spacecraft, the method comprising: 
     operatively coupling an outside face-sheet and an inside face-sheet to a core; 
     positioning at least one heat pipe between the outside face-sheet and the inside face-sheet; and 
     operatively coupling an external structural reinforcement member to the outside face-sheet. 
     H1. The method of paragraph H, further comprising the method of any of paragraphs D-D8. 
     H2. The method of any of paragraphs H-H1, wherein the radiator panel includes the corresponding subject matter of any of paragraphs E-E14. 
     H3. The method of any of paragraphs H-H2, wherein the method does not include operatively coupling an internal structural reinforcement member to the inside face-sheet. 
     H4. The method of any of paragraphs H-H3, wherein the method results in a radiator panel according to any of paragraphs E-E14. 
     The various disclosed elements of systems, apparatuses, and kits disclosed herein and the various disclosed steps of methods disclosed herein are not required to all systems, apparatuses, kits, and methods according to the present disclosure. Moreover, one or more of the various elements and steps disclosed herein may define independent inventive subject matter that is separate and apart from the whole of a disclosed system, apparatus, kit, or method. Accordingly, such inventive subject matter is not required to be associated with the specific systems, apparatuses, kits, and methods that are expressly disclosed herein, and such inventive subject matter may find utility in systems, apparatuses, kits, and/or methods that are not expressly disclosed herein. 
     As used herein the terms “adapted” and “configured” mean that the element, component, or other subject matter is designed and/or intended to perform a given function. Thus, the use of the terms “adapted” and “configured” should not be construed to mean that a given element, component, or other subject matter is simply “capable of” performing a given function but that the element, component, and/or other subject matter is specifically selected, created, implemented, utilized, programmed, and/or designed for the purpose of performing the function. It is also within the scope of the present disclosure that elements, components, and/or other recited subject matter that is recited as being adapted to perform a particular function may additionally or alternatively be described as being configured to perform that function, and vice versa. 
     The disclosure set forth above encompasses multiple distinct inventions with independent utility. While each of these inventions has been disclosed in its preferred form or method, the specific alternatives, embodiments, and/or methods thereof as disclosed and illustrated herein are not to be considered in a limiting sense, as numerous variations are possible. The present disclosure includes all novel and non-obvious combinations and subcombinations of the various elements, features, functions, properties, methods, and/or steps disclosed herein. Similarly, where any disclosure above or claim below recites “a” or “a first” element, step of a method, or the equivalent thereof, such disclosure or claim should be understood to include incorporation of one or more such elements or steps, neither requiring nor excluding two or more such elements or steps. 
     It is believed that the following claims particularly point out certain combinations and subcombinations that are directed to one of the disclosed inventions and are novel and non-obvious. Inventions embodied in other combinations and subcombinations of features, functions, elements, properties, methods, and/or steps may be claimed through amendment of the present claims or presentation of new claims in this or a related application. Such amended or new claims, whether they are directed to a different invention or directed to the same invention, whether different, broader, narrower, or equal in scope to the original claims, also are regarded as within the subject matter of the inventions of the present disclosure.