Patent Description:
Toroidal (ring-shaped) space stations, in particular those that rotate so that centripetal acceleration provides a form of artificial gravity for the space station, have been proposed since the early <NUM>th century. These include a revolving space station design originally conceived by Konstantin Tsiolkovsky in <NUM> and further developed by Herman Potočnik in the <NUM> and Wernher von Braun in the <NUM>, the Stanford torus by NASA and others at Stanford University in <NUM>, and the proposal by Hughes Aircraft for a wheel-shaped space station in the <NUM>. However, no toroidal space station has ever been constructed.

The decommissioning and disposal of the International Space Station has been scheduled for <NUM>, and as a result interest in toroidal space stations is increasing.

Proposed toroidal space stations are usually very large in size, with diameters extending from the hundreds of metres to several kilometres. They are required to be so large to achieve the rate of spin necessary to provide artificial gravity, such as Earth gravity, around the rim while rotating sufficiently slowly to be physiologically acceptable to humans who experience adverse vestibular and other reactions to highspeed physical rotation. In addition, some designs of toroidal space stations feature large amounts of tension and bracing structures that bisect the ring (such as hub-and-spoke-type designs), which increases the amount of material that needs to be transported into space, adds complexity to the construction process there, and increases overall costs. As a result, the viable transportation into space of the materials from which to construct toroidal space stations presents a significant technical and operational challenge.

In addition, existing proposals require re-purposing and/or re-outfitting of existing elements (e.g. space vehicle structures), involving significant construction or modification in space, which is also complex and costly.

Known proposed methods of constructing toroidal space stations include the following examples:.

All of these known systems require the transportation of prefabricated modules or complex new structures into space, or the repurposing of vehicle material (such as spent propellant tanks) in order to construct the toroidal space station.

An expandible structure, not described as being in the field of space engineering or toroidal space stations, is shown in the following document:
<CIT>, discloses an extendible structure that can be collapsed to a shorter length and extended to a longer length. A pair of station members are interconnected by at least three longeron members. Each longeron member has two longeron elements that are pivoted together so they can fold toward one another or aligned to form a column. Each element is pivoted to a respective station member. Stays rigidify the structure when extended, and are opposed by buckling springs (Euler columns) that exert an outward resultant force on each longeron member at its folding point.

The present invention seeks to solve and/or mitigate some or all of the above-mentioned problems. Alternatively, and/or additionally, the present invention seeks to provide improved expandable structural modules for toroidal space station structures, improved space station substructures, improved toroidal space station structures, and improved methods of constructing toroidal space station structures.

In accordance with a first aspect of the invention there is provided an expandable structural module for a toroidal space station structure, the expandable structural module comprising:.

It will be appreciated that a toroidal space station structure may be a functioning inhabited space station (or the underlying structural thereof), but may also be a demonstration system used to test a rotating space station design.

By having the expandable structural module transformable between a collapsed configuration and an expanded configuration, the expandable module can be transported into space in the collapsed configuration, and transformed into the expanded configuration thereafter. This allows efficient use of launch vehicle volume during transportation into space. In addition, the first bulkhead being arranged to be attached to a corresponding bulkhead of a further expandable structural module allows for easier construction of a toroidal space station structure from the expandable structural modules, as once in space each expandable structural module can be expanded into the expanded configuration and a plurality of such modules attached together, rather than the expandable structural modules having to be constructed in space from their component parts.

Each structural member may be connected to the perimeter of the first bulkhead and to the perimeter of the second bulkhead. It will be appreciated that the perimeters of the bulkheads include locations in the vicinity of the outer edges of the bulkheads, as well as on the outer edges themselves.

The first distance between the first bulkhead and second bulkhead in the collapsed configuration may be zero. At the first distance, the first bulkhead and the second bulkhead may be touching. The second distance between the first bulkhead and second bulkhead in the expanded configuration may be such that the structural members are extended to form a straight or substantially straight strut.

The expandable structural module may comprise a number of sides that are orthogonal to the faces of each of the bulkheads. Each bulkhead face may be perpendicular to the length of the structural members when the structural members are in the extended position.

The expandable structural module may be polygonal in cross-section. The cross-section of the expandable structural module may be a polygon with between five and sixteen sides. The cross-section of the expandable module may be a polygon with eight sides. The polygon may be a regular octagon. Such a polygon results in the efficient use of space by the expandable structural module within a payload compartment of a space vehicle (which may, for example, have a circular cross-section).

Each structural member may comprise a first part connected to the first bulkhead and a second part connected to the second bulkhead, the first part being hingably connected to the second part. The hinge connection the between the first part and second part of the structural members may be a stored-energy joint, configured such that the joint is biased to move the first part and second part away from each other to move the structural member from the collapsed configuration to the extended configuration.

The first bulkhead may comprise a plurality of struts extending from the perimeter towards the centre of the bulkhead, wherein each strut has on its surface facing the interior of the expandable module a recess, and wherein each strut is arranged so that a corresponding structural member of the plurality of structural members is at least partially located within the recess when the structural members are in the collapsed position. The second bulkhead may also comprise such a plurality of struts. In this way, the structural members have a reduced or no effect on the first distance between the first bulkhead and second bulkhead when the expandable module is in the collapsed position.

The expandable module may further comprise a plurality of brace members connecting the first bulkhead and second bulkhead, wherein the brace members are located between the structural members. The first bulkhead may comprise a plurality of struts extending from the perimeter towards the centre of the bulkhead, wherein each strut has on its surface facing the interior of the expandable module a recess, and wherein each strut is arranged so that a corresponding brace member of the plurality of brace members is at least partially located within the recess when the structural members are in the collapsed position. Again, the second bulkhead may also comprise such a plurality of struts. In this way, again, the brace members have a reduced or no effect on the first distance between the first bulkhead and second bulkhead when the expandable module is in the collapsed position. The recess in which a brace member is at least partially located may be the same recess in which a strut is at least partially located, or may be a separate recess. Different parts of a brace member may be located in different recesses.

The first bulkhead comprises a spacing mechanism for attaching the first bulkhead to the corresponding bulkhead of the further expandable module. The spacing mechanism is arranged to move between a shortened configuration in which the first bulkhead and the corresponding bulkhead are held parallel to each other, and a spaced configuration in which the first bulkhead and the corresponding bulkhead are held at a non-zero angle with respect to each other. In this way, when multiple expandable structural modules are attached together in the expanded configuration, connected by spacing mechanisms is the spaced configuration, they will form an arc. Conversely, when the spacing mechanisms is the shortened configuration, the multiple expandable modules will form a straight line.

The shortened configuration may correspond to a substantially closed position, where the perimeters of the first bulkhead and the corresponding bulkhead are in contact around the substantially the entire perimeter of the first bulkhead and corresponding bulkhead. The spaced configuration may correspond to an open position where the perimeters first bulkhead and the corresponding bulkhead are not touching over a substantial part of their perimeters.

The spacing mechanism may comprise one or more hinged connectors, a first end of each hinged connector being hingably mounted to the perimeter of the first bulkhead. The one or more hinged connectors may be arranged to be hingably attached to one or more corresponding hinged connectors hingably mounted to the perimeter of the corresponding bulkhead of the further expandable module.

At least some of the one or more hinged connectors may comprise actuatable flaps. The one or more actuatable flaps are configured to attach to the corresponding hinged connectors hingably mounted to the perimeter of the corresponding bulkhead of the further expandable structural module. Each of the one or more actuatable flaps may be rotatable to an angle with respect to the face of the bulkhead that results in the first bulkhead and the corresponding bulkhead being in the non-zero angle when they are in the spaced configuration. The rotation of the actuatable flaps may apply a force to the face of the bulkhead and the connecting surface of the further frame module such that the connecting surface and the further frame module are displaced relative to each other proximal to their respective perimeters.

The spacing mechanism allows advantageously for displacement in a manner which requires no collisions or impacts between the face of the bulkhead and the connecting surface of the further frame module, thereby reducing the likelihood of any damage occurring as the modular space station is assembled in orbit. As the first non-zero angle increases, the curve or arc of any substructure formed of the structural members becomes more pronounced. Thus, advantageously, the spacing mechanism allows for the control or adjustment of the curve or arc of a substructure formed of the structural modules.

The expandable structural module may comprise one or more deployable photovoltaic blankets. The one or more photovoltaic blankets may be stowable, and configured to be deployed once the expandable module is transformed to the expanded configuration. The one or more photovoltaic blankets may form one or more sides of the expandable module. The one or more photovoltaic blankets may be deployed automatically.

The expandable structural module may further comprise an engine system. The engine system may comprise one or more low-thrust engines. Each of the one or more engines may be mounted on hinged arms, so that they can be moved between a stowed configuration and a deployed configuration. The one or more engines when in the deployed configuration can apply thrust to the assembled toroidal space station structure to rotate it when in space. The engines may be rotatably-mounted between the hinged arms. The engines are optionally rotatably mounted on a gimball. This is advantageous as it allows the direction of thrust produced by the engines, and hence the direction of the spin of a space station comprising the engine system, to be reversed by rotating the engines.

The engine system may have a generally frustoconical shape, or be arranged to fit within a generally frustoconical shape, to fit into the payload compartment of a payload delivery vehicle (for example, the nose of a rocket). The engine system may comprise a frame having generally frustoconical shape.

The expandable structural module may further comprise a propulsion system. The propulsion system may comprise a plurality of engines. The engines may be mounted between the struts of a bulkhead.

The expandable structural module may further comprise an attitude control system. The attitude control system may comprise one or more clustered thruster banks. The clustered thruster banks may be located around the perimeter of the first bulkhead and/or second bulkhead.

The expandable structural module may comprise a robotic arm for grasping another expandable structural module, and bringing the another expandable structural module towards the expandable structural module so that the expandable structural modules can be attached together.

In accordance with a second aspect of the invention there is provided a space station substructure comprising a first expandable structural module and a second expandable structural module as described above, wherein the first bulkhead of the first expandable module is attached to the first bulkhead of the second expandable structural module to form at least part of the space station substructure, the space station substructure being transformable between:.

The space station substructure may comprise a multiplicity of expandable structural modules attached together end-to-end. The space station substructure comprises at least two expandable structural modules, and may comprise up to ten, up to twenty, up to thirty, or even more expandable structural modules. It will be appreciated that while the space station substructure could comprise only two expandable structural modules, in order to have a substructure with an appreciable arc, significantly more than two structural modules will be required.

Where the multiplicity of expandable structural modules are held together so that the faces of their bulkheads are at a non-zero angle with respect to each other, the space station substructure will form an arc.

The space station substructure may further comprise an engine system. The engine system may be mounted on or adjacent to the outermost bulkhead of an expandable structural module at an end of the space station substructure.

The space station substructure may further comprise a propulsion system. The propulsion system may be mounted to the outermost bulkhead of an expandable structural module at an end of the space station substructure. Where the space station substructure also comprises an engine system, the engine system and propulsion system may be mounted on the exposed bulkheads of the expandable structural module at opposite ends of the space station substructure.

The space station substructure may further comprise an attitude control system. The attitude control system may be mounted to the outside of an expandable structural module at an end of the space station substructure. Where the space station substructure also comprises a propulsion system, the attitude control system may be mounted to the expandable structural module to which the propulsion system is mounted.

In accordance with a third aspect of the invention there is provided a toroidal space station structure comprising a plurality of expandable structural modules as described above.

The structure of the toroidal space station structure may be configured to transmit loads around its perimeter. In this configuration, the toroidal space station structure may be hubless and/or spokeless such that there are no trusses or other supporting members within the area enclosed by the toroidal ring. The toroidal space station structure may be a demonstration system. This allows a design for a toroidal space station to be tested as a proof of concept. Alternatively, the toroidal space station structure may be the structure of an inhabitable space station.

In accordance with a fourth aspect of the invention there is provided a method of constructing a toroidal space station structure, the method comprising the steps of:.

In this way, a particularly efficient method of transporting the materials for a toroidal space station structure into space, for example within a launch vehicle payload compartment, and constructing the toroidal space station structure in space, is provided.

The expandable structural modules may be transformed into the expanded configuration before or after being attached to other expandable structural modules.

The method may further comprise, prior to the step of transporting the plurality of expandable structural modules into space, the step of attaching the plurality of expandable structural modules together to form a plurality of space station substructures as described above;.

The space station substructures may be brought together in space using attitude control systems that have been described above. The substructures may be brought together to form a part (for example, half) of a toroidal space station structure before being brought together to form the complete space station.

An expandable structural module for a toroidal space station structure in accordance with an embodiment of the invention is now described, with reference to <FIG>. <FIG> shows the expandable structural module <NUM> in an expanded configuration. The structural frame of the expandable structural module <NUM> is shown, with any panelling, external photovoltaic arrays or the like omitted for the sake of clarity.

The expandable structural module <NUM> takes the general form of an octagonal prism. At either end of the expandable structural module <NUM> are bulkheads <NUM>, arranged parallel to each other. Each bulkhead <NUM> comprises an outer perimeter frame <NUM>, the perimeter frame <NUM> taking the form of an octagon. The perimeter frame <NUM> is formed of an octagonal beam <NUM> with an outer flange <NUM>. On each bulkhead <NUM>, eight radial struts <NUM> extend inwardly from the perimeter frame <NUM> to a central ring <NUM>, arranged equidistantly around the perimeter of the bulkhead <NUM>. Each radial strut <NUM> is formed from a web <NUM> with each radial strut having flanges <NUM>. The spaces between perimeter frame <NUM>, radial struts <NUM> and central ring <NUM> form voids <NUM>, <NUM>, i.e. regions of free space, in the bulkheads <NUM>.

The bulkheads <NUM> are connected by structural members <NUM> and X-braces <NUM>, which form the sides of the expandable structural module <NUM>. Eight structural members <NUM> extend between the bulkheads <NUM>, in a direction orthogonal to the plane of each bulkhead <NUM>. Each structural member <NUM> comprises a tube <NUM> hinged at its midpoint with a spring-loaded hinge <NUM>, and at each end connected to a bulkhead <NUM> by a hinge <NUM>. Eight X-braces <NUM> span the rectangular planes that form the sides of the prism, each plane being defined by two adjacent structural members <NUM>. Each X-brace <NUM> comprises two frames <NUM> of a truncated triangle shape. The base of each frame <NUM> is connected at either side to one of the bulkheads <NUM> by a hinge <NUM>, and the truncated tops of the frames <NUM> are connected together by a hinge <NUM>.

<FIG> shows the expandable structural module <NUM> in a collapsed configuration, and <FIG> shows the expandable structural module <NUM> midway between the expanded configuration and collapsed configuration. In the collapsed configuration, the two bulkheads <NUM> are in contact across their entire perimeter <NUM>, defining a contact region <NUM>. The expandable structural module <NUM> is moved to the collapsed configuration by folding the structural member <NUM> using the hinges <NUM> and <NUM>, so that the tubes <NUM> are folded against each other such that they are parallel and touching along their length. In the collapsed configuration, the structural members <NUM> are located within recesses formed by flanges <NUM> of the radial struts <NUM>. Similarly, the X-braces <NUM> are folded using the hinges <NUM> and <NUM>, such that the frames <NUM> are touching along their length and are located within the same recesses as the structural members <NUM>.

In this way, it can be seen that the expandable structural module <NUM> can be transformed between an expanded configuration and a collapsed configuration. In the collapsed configuration the structural members <NUM> and X-braces <NUM> fold flat and are located within the recesses of the bulkheads <NUM>, so that bulkheads <NUM> are touching and the expandable structural module <NUM> has minimal thickness for transportation. As mentioned above, the hinges <NUM> of the structural members <NUM> are spring-loaded, which biases the expandable structural module <NUM> to move from the collapsed configuration to the expanded configuration, as described in more detail below.

<FIG> shows the expandable structural module <NUM> again in the expanded configuration. On seven of the eight sides of the expandable structural module <NUM> are photovoltaic blankets <NUM>, each of which covers the area of the side spanned by the X-braces <NUM>. The photovoltaic blankets <NUM> are contractible, so that they can be fixed at each end to one of the bulkheads <NUM>, and contract and expand as required as the expandable structural module <NUM> moves between the collapsed configuration and the expanded configuration. It will be appreciated that photovoltaic blankets <NUM> may be provided on none, some or all of the sides of an expandable structural module <NUM>, as desired.

<FIG> shows bulkheads <NUM> of two different expandable structural modules <NUM> connected on first sides by a spacing mechanism <NUM>, with the spacing mechanism <NUM> being shown in more detail on <FIG>. The spacing mechanism <NUM> comprises two hinged connectors 40a mounted on the perimeter of a first bulkhead <NUM> of the expandable structural modules <NUM>. The spacing mechanism <NUM> also comprises a further two hinged connectors <NUM> mounted on the perimeter of the second bulkhead <NUM> of the expandable modules <NUM>. Each hinged connector 40a is hingably connected to a corresponding hinged connector <NUM> by a pivot <NUM>. Electric motors <NUM> mounted on each bulkhead <NUM> are connected to four gear reduction drives <NUM>, each of which is associated with one of the hinged connectors 40a, <NUM>, so that the electric motors <NUM> can, via the gear reduction drives <NUM>, cause the hinged connectors 40a and <NUM> to rotate with respect to the bulkheads <NUM>.

Second sides of the bulkheads <NUM> opposite the first sides are hingably connected (not visible in <FIG>). Further, on the sides of the bulkheads <NUM> between the first sides and second sides are stays <NUM>, which allow those sides of the bulkheads <NUM> to move together and apart, but prevent the bulkheads <NUM> moving apart by more than a desired distance.

In <FIG> the spacing mechanism <NUM> is shown in a spaced configuration, in which the hinged connectors 40a and <NUM> are in a straight line so giving a maximum distance between the bulkheads <NUM>. As can be seen, this causes the bulkheads <NUM> to be held at a non-zero angle with respect to each other. The electrical motors <NUM> can, via the gear reduction drives <NUM>, rotate the hinged connectors 40a and <NUM> towards the bulkheads <NUM> to which they are attached, so that the spacing mechanism <NUM> moves to a shortened, and ultimately, closed, configuration in which the first bulkhead and the corresponding bulkhead are held parallel to each other, so that they are touching. (Expandable structural modules <NUM> connected by spacing mechanism <NUM> in the shortened configuration are shown in <FIG>, <FIG> and <FIG> described later below.

An engine system for use with the expandable structural module <NUM> is now described with reference to <FIG> shows the engine system <NUM> with engines deployed outside the frame of the engine system, and <FIG> shows the engine system <NUM> with engines stowed within the frame of the engine system.

The base <NUM> of the engine system <NUM> is arranged to be attached to the bulkhead <NUM> of an expandable structural module <NUM>, having the same size and shape as a bulkhead <NUM>. The engine system <NUM> has a generally frustoconically-shape frame, formed of struts <NUM> that extend from the base <NUM> and then taper to a top <NUM>, which is also octagonal shaped but with a diameter less than the base <NUM>. A propellant tank <NUM> is mounted within the frame of the engine system <NUM>, and three low-thrust engines <NUM> are mounted on hinged arms <NUM> that can be moved between a deployed position in which the engines <NUM> are positioned away from the frame of the engine system <NUM>, as shown in <FIG>, and a stowed position in which the engines <NUM> and arms <NUM> are stowed within the frame of the engine system <NUM>, as shown in <FIG>. Each engine <NUM> is gimbally-mounted between the hinged arms <NUM> so that its direction of thrust can be reversed by rotating it on the gimbal.

A space station substructure in accordance with an embodiment of the invention is now described, with reference to <FIG>.

<FIG> shows the space station substructure <NUM> in a stowable configuration, stowed within a schematically shown launch vehicle payload compartment <NUM>. <FIG> is another view of the space station substructure <NUM> without the launch vehicle payload compartment <NUM> shown. The space station substructure <NUM> comprises a plurality of expandable structural modules <NUM> attached together. The expandable structural modules <NUM> are all in the collapsed configuration, and the expandable structural modules <NUM> are attached together by spacing mechanisms <NUM> and hinges <NUM>, all of which are in the shortened configuration. Thus, as can be seen, the expandable structural modules <NUM> are stacked together in parallel, taking up the minimum space within the launch vehicle payload compartment. An engine system <NUM> is attached to the topmost expandable module <NUM>, extending into the tapered nose of the launch vehicle payload compartment <NUM>.

At the base of the space station substructure <NUM> shown in <FIG>, i.e. at the opposite end to the engine system <NUM>, is a propulsion system <NUM>. The propulsion system <NUM> is located in the voids <NUM> and <NUM> formed between the radial struts <NUM> of the bulkheads <NUM> of the expandable structural modules <NUM>. The propulsion system <NUM> comprises four engines <NUM>, corresponding propellant tanks <NUM>, and corresponding pressurant tanks <NUM> above the propellant tanks <NUM>. Additionally, on the exterior of the space station substructure <NUM> is an attitude control system <NUM>, which comprises four thruster clusters <NUM> mounted on the perimeter of the bulkhead <NUM> at the base of the space station substructure <NUM>, and four thruster clusters <NUM> mounted on the perimeter of the bulkhead <NUM> at the top of the space station substructure <NUM>. Each thruster cluster <NUM>, <NUM> comprises five thrusters 66a per cluster to provide thrust in three axes. The use of the propulsion system <NUM> and attitude control system <NUM> is described in more detail below.

On the outermost face of the base of the space station substructure <NUM> is a base fixing <NUM>, which corresponds in size and shape to the top <NUM> of the engine system <NUM>, the use of which is described in more detail below.

<FIG> shows a portion of the space station substructure <NUM> in a deployed configuration, in which each expandable structural module <NUM> is in the expanded configuration, and the spacing mechanisms <NUM> connecting the expandable structural modules <NUM> are in the spaced configuration. As can be seen, the spacing mechanisms <NUM> are holding each pair of expandable structural modules <NUM> at a non-zero angle to each other, creating gaps <NUM> and so causing the space station substructure <NUM> to form an arc.

<FIG> shows a first space station substructure <NUM> in the deployed configuration shown in <FIG>, and a second space station substructure <NUM> in the stowable configuration shown in <FIG> and <FIG>. A robotic arm <NUM> on the base of the first space station substructure <NUM> has grasped the second space station substructure <NUM>, following the second space station substructure <NUM> having arrived in the vicinity of the first space station substructure <NUM> using the propulsion system <NUM> and attitude control system <NUM> of the second space station substructure <NUM>. (Also, if required, the propulsion system <NUM> and attitude control system <NUM> of the first space station substructure <NUM> may be used to bring the first space station substructures <NUM> and second space station substructures <NUM> together.

Once the robotic arm <NUM> has grasped the second space station substructure <NUM>, it can manipulate it to bring it into contact with the first space station substructure <NUM>. The propulsion system <NUM> and/or attitude control system <NUM> of the second space station substructure <NUM> can be used to assist the robotic arm <NUM> in moving and aligning the second space station substructure <NUM> at close quarters, if required. Similarly, the propulsion system <NUM> and/or attitude control system <NUM> of the first space station substructure <NUM> can be used to keep the first space station substructure <NUM> in the desired position, if required. The propulsion systems <NUM> will not usually be used during close-quarters manipulation of the first space station substructure <NUM> and second space station substructure <NUM>, for example, while moving and aligning the second space station substructure <NUM> with the robot arm <NUM>, as the engines <NUM> of the propulsion systems <NUM> are high thrust and unidirectional and unsuitable for fine positioning. The attitude control system <NUM> would usually be used at close quarters until the substructure <NUM> is grasped by the robotic arm <NUM>, at which point the attitude control system <NUM> is no longer used.

In particular, the top <NUM> of the engine system <NUM> of the second space station substructure <NUM> shown in <FIG> is brought into contact with the base fixing <NUM> of the first space station <NUM> shown in <FIG>, allowing the base fixing <NUM> and top <NUM> to be connected together to connect the first space station substructure <NUM> to the second space station substructure <NUM>.

A toroidal space station structure in accordance with an embodiment of the invention is now described, with reference to <FIG>. The toroidal space station structure <NUM> is constructed from six space station substructures <NUM>, as described below with reference to <FIG> and <FIG>. As can be seen, each of the six space station substructures <NUM> forms an arc that subtends an angle <NUM>, i.e. an angle of <NUM>°, so spanning an arc <NUM>, so that together the six space station substructures <NUM> form a closed ring of <NUM>° to provide the complete toroidal space station structure <NUM>. The toroidal space station structure <NUM> is in the form of a ring only, without any central hub, radiating spokes or truss structures or the like.

The toroidal space station structure <NUM> in <FIG> is in orbit around the Earth, moving in the direction <NUM> shown. The toroidal space station structure <NUM> can be rotated in either the anticlockwise direction <NUM> or the clockwise direction <NUM>, so that centripetal force resulting from the rotation forms artificial gravity for the toroidal space station structure <NUM>. In particular, in the arrangement shown <FIG> the engines <NUM> of the engine systems <NUM> of the six space station substructures <NUM> can exert a force to rotate the toroidal space station structure <NUM> in the clockwise direction <NUM>.

The construction of the toroidal space station structure <NUM> from the six space station substructures <NUM> in accordance with an embodiment of the invention is now described with reference to <FIG> and <FIG>.

In a first step (not shown), the six space station substructures <NUM> are transported into space, in this case in separate launch vehicles and at different times, each in the stowable configuration by a respective launch vehicle in its payload compartment <NUM>.

In a next step <NUM>, a first space station substructure <NUM> [a] is moved propelled to its required position in orbit [b] using its propulsion system <NUM> and attitude control system <NUM>. The first space station substructure <NUM> is then transformed into the deployed configuration [c], by moving the various expandable structural modules to the expanded configuration and the various spacing mechanisms to the spaced configuration.

In a next step <NUM>, a second space station substructure <NUM> [d] is moved to its required position in the vicinity of an end of the first space station substructure <NUM>, again using its propulsion system <NUM> and attitude control system <NUM>. An end of the second space station substructure <NUM> is then connected to the first space station substructure <NUM> [e], and moved transformed into the deployed configuration [f]. As can be seen, the end of the second space station substructure <NUM> comprising the engine system <NUM> is connected to the end of the first space station substructure <NUM> opposite to the end comprising the engine system <NUM>.

In a next similar step <NUM>, a third space station substructure <NUM> [g] is moved to its required position in the vicinity of the end of the second space station substructure <NUM> that is not connected to the first space station substructure <NUM>. An end of the third space station substructure <NUM> is connected to the end of the second space station substructures <NUM> [h], and the third space station, substructure <NUM> is then transformed into the deployed configuration [j]. Similarly, it can be seen that the end of the third substructure <NUM> comprising the engine system <NUM> is connected to the end of the second substructure <NUM> opposite to the end comprising the engine system <NUM>.

In this way, the three space station substructures <NUM> are joined together to form an <NUM>° arc, i.e. a first connected set <NUM> of three space station substructures <NUM> that provides half of the toroidal space station structure <NUM>. The steps <NUM> to <NUM> are then repeated with the remaining three substructures <NUM> as steps <NUM> to <NUM>, to form a second connected set <NUM> of three substructures <NUM> also in the form of a <NUM>° arc.

In a next step <NUM>, the ends of the two connected sets <NUM> are brought together, using the attitude control systems <NUM> of the six substructures <NUM>. In particular, the end [k] of the first connected set <NUM>, which is the base (i.e. an expandable structural module <NUM>) of six substructures <NUM>, and the end [l] of the second connected set <NUM>, which is the top (i.e. engine system <NUM>) of six substructures <NUM>, are moved to the position [p]. Correspondingly, the other end [m] of the first connected set <NUM>, which is the top (i.e. engine system <NUM>) of six substructures <NUM>, and the other end [o] of the second connected set <NUM>, which is the base (i.e. an expandable module <NUM>) of a six substructures <NUM>, are moved to the position [q].

In a final step <NUM>, the first two ends of the first connected set <NUM> and second connected set <NUM> are connected together [r], and the second two ends of the first connected set <NUM> and second connected set <NUM> are connected together [s] simultaneously, to form the complete toroidal space station structure <NUM>.

<FIG> shows a disassembled toroidal space station structure according to an embodiment of the invention. The toroidal space station structure <NUM> can be dissembled into a number of components for further construction applications in space. The disassembly procedure follows the construction method described above in reverse order, to separate the six space station subsections <NUM>. The subsections <NUM> are then straightened by retracting the mechanisms <NUM> between the expandable structural modules <NUM> into the shortened configuration. The resulting six separate space station substructures <NUM> are transformed to straight lengths that can then be used for a variety of other space purposes, improving the life-cycle sustainability of the toroidal space station structure <NUM>.

While the present invention has been described and illustrated with reference to particular embodiments, it will be appreciated by those of ordinary skill in the art that the invention lends itself to many different variations not specifically illustrated herein.

In other embodiments, the number of sides of the expandable structural module, if it has a polygonal cross-section, may for example vary between <NUM> and <NUM> sides. Alternatively, the expandable structural module may have another cross-section, for example a circular cross-section.

In other embodiments, the number of substructures/segments and the non-zero angle between the bulkheads of the connected expandable structural modules may be altered to change the diameter of the toroidal space station structure that results from the connection of the substructures.

In other embodiments, the substructure may comprise anywhere between a minimum of two expandable structural modules and a maximum of as many expandable structural modules that can be accommodated by the launch vehicle payload compartment intended to launch the substructure into space.

In other embodiments, rather than being hinged the spacing mechanism may - comprise one or more pistons or any other suitable mechanism for providing adjustable spacing.

Reference should be made to the claims for determining the scope of the present invention.

Claim 1:
An expandable structural module (<NUM>) for a toroidal space station structure, the expandable structural module (<NUM>) comprising:
a first bulkhead (<NUM>) and a second bulkhead (<NUM>) forming first and second opposite ends of the expandable structural module (<NUM>), the first bulkhead (<NUM>) being arranged to be attached to a corresponding bulkhead of a further adjacent expandable structural module;
a plurality of adjustable structural members (<NUM>) connecting the first bulkhead and the second bulkhead (<NUM>);
wherein the expandable structural module is transformable between:
a collapsed configuration in which the first bulkhead (<NUM>) and second bulkhead (<NUM>) are held a first distance apart by the structural members (<NUM>); and
an expanded configuration in which the first bulkhead (<NUM>) and second bulkhead (<NUM>) are held a second distance apart by the structural members (<NUM>), the second distance being larger than the first distance,
characterised in that the first bulkhead comprises a spacing mechanism (<NUM>) for attaching the first bulkhead (<NUM>) to the corresponding bulkhead of the adjacent and adjoining expandable structural module and
wherein the spacing mechanism (<NUM>) is arranged to transform between a shortened configuration in which the first bulkhead (<NUM>) and the corresponding bulkhead are held parallel to each other, and a spaced configuration in which the first bulkhead and the corresponding bulkhead are held at a non-zero angle with respect to each other.