Abstract:
A rocket launch tower is provided, including: a vertical support structure including two or more guide towers defining a vertical shaft between the two or more guide towers, each guide tower including one or more pulleys engaging one or more cables; a platform located within the vertical shaft and connected to the one or more cables; a drive mechanism that applies a force to the one or more cables to accelerate the platform along a trajectory within the vertical shaft; one or more sensors collecting data regarding the position of the platform along the trajectory within the vertical shaft and communicating the platform position data to a controller, the controller in communication with an acceleration control system including one or more brakes acting on the platform; wherein the controller causes the acceleration control system to actively correct the platform acceleration towards an intended platform acceleration.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application claims priority to and the benefit of U.S. Provisional Application 61/858,549, filed Jul. 25, 2013 and to U.S. Provisional Application 61/869,322, filed Aug. 23, 2013 both of which are hereby incorporated by reference. 
    
    
     BACKGROUND OF THE INVENTION 
     The present subject matter relates generally to a rocket launch tower having pre-acceleration of the rocket before powered flight. More specifically, the present invention relates to a rocket launch tower that uses falling counterweights to accelerate and stabilize a platform supporting a rocket at a higher rate of speed than the speed of the counterweights. 
     Launching rockets into space is very energy intensive and inefficient. Modern launch vehicles are able to deliver between 1% (Space Shuttle) and at most 4% (Saturn V) of the total vehicle mass at launch into low earth orbit. This makes it extremely costly to deliver even a small payload to space (going rates are $5000-$10,000 per kilogram). A number of inventions have been proposed to provide ground-based power for helping to launch rockets but so far none have been implemented successfully. 
     One previously proposed solution involves using falling counterweights with a simple fixed pulley arrangement to accelerate a rocket upward (See, for example, U.S. Pat. Nos. 3,088,698 and 7,530,532). Using this solution, the greatest acceleration a falling object can achieve is 1 g. A counterweight using a simple fixed pulley that is lifting a load will always accelerate at less than 1 g. Therefore, a simple pulley lifting a rocket launch platform will accelerate a rocket at less that 1 g. As a traditional rocket already accelerates upward at around 0.5 g such a counterweight launch arrangement does not provide much benefit, or requires an extremely tall tower structure. 
     Another previously proposed solution involves recirculating exhaust gas from a rocket to push a launch platform upward (See, for example, U.S. Pat. Nos. 3,363,508 and 6,318,229). Containing recirculated exhaust gas requires either a chamber sealed to the engines of the rocket (which is technically complicated and prone to damage the engines due to backpressure) or an unsealed or partially sealed chamber that would provide inconsistent pressure and therefore inconsistent acceleration of the rocket. 
     A further previously proposed solution involves using electric motors to pull cables that accelerate a rocket upward (See, for example, U.S. Pat. No. 3,363,508). Electric motors to propel a rocket would be excessively large and require an excessive amount of energy at launch—this is technically difficult and expensive to achieve. 
     Yet another previously proposed solution involves using a compressed gas to rapidly inflate a chamber underneath a rocket, propelling it upwards (U.S. Pat. No. 6,354,182). Propelling a rocket using an expanding gas requires a sealed chamber under the rocket that remains sealed as the rocket accelerates upward. Such a large sealed chamber (like a giant gun barrel) is impractical and excessively expensive to manufacture for the size necessary, and the machinery necessary to smoothly but powerfully fill this giant cylindrical barrel would be excessively large, complex, and expensive. 
     An even further previously proposed solution involves stretching elastic material under a rocket and using it to propel a rocket upward (See, for example, U.S. Pat. No. 6,354,182). No such material exists that will contain sufficient energy over a sufficient range of motion to make an elastic launch system useful or practical. 
     Moreover, none of the existing rocket launch mechanisms provide the capacity to finely adjust and control the upward acceleration in the range appropriate and useful for a rocket. Too much acceleration (over about 5 g) will damage the rocket, and too little will not provide enough assistance to guarantee the rocket reaches orbit with its additional payload. It is important that the upward acceleration can be finely controlled in the useful range for a rocket. 
     Additionally, none of the existing rocket launch mechanisms guarantee that the rocket will be accelerated in a straight line, with no tilting or lateral movement (movement perpendicular to the centerline of the rocket). Rockets are relatively fragile in all directions excepting a steady push from below, and any system that does not provide for a smooth enough, straight vertical acceleration is prone to damage the rocket. 
     Finally, prior attempts failed to take into account the limited acceleration provided by a simple (non-multiplying) pulley arrangement, as well as the need to precisely control the acceleration as well as lateral and tilting movement of the launch platform. In the absence of these features, a gravity-powered launch tower would not be useful. As evidence, none was ever built. 
     What is needed are mechanisms to address the weaknesses in current launch technology and substantially improve the payload capacity of existing and future rockets for relatively low cost. 
     Accordingly, there is a need for a rocket launch tower including a pulley system that drives a platform that is dynamically stabilized, as described herein. 
     BRIEF SUMMARY OF THE INVENTION 
     To meet the needs described above and others, the present disclosure provides a rocket launch tower including a pulley system that drives a platform that is dynamically stabilized. By providing a rocket launch tower that includes a pulley system that drives a platform that is dynamically adjusted by an active stabilization subsystem including one or more stability mechanisms, the launch tower will provide a means for launching existing rockets with an initial upward velocity to allow a given rocket to carry a heavier payload into space. Additionally, by providing a rocket launch tower that includes a braking system and active stability system, the rocket launch tower may provide stable launch of the rocket while providing a mechanism to prevent loss of the rocket due to instability that may be caused by the pulley system. 
     In an embodiment, the rocket launch tower includes a platform that supports a rocket. In use, the rocket launch tower launches the rocket from the upward-moving platform thereby imparting energy into the rocket before or in conjunction with the rocket using its own propellant. 
     The platform may be connected to cables to provide the upward force during launch. The cables may, in turn, connect the platform to an arrangement of counterweights via a pulley system. During launch, the counterweights are allowed to fall, accelerating the cables to cause upward movement of the platform. A surrounding structure guides the platform and provides support to the cables via pulleys at the top of the surrounding structure that engage the cables. The surrounding structure may include one or more guide towers that may guide the platform during ascent. 
     The cables may be connected to the platform, may run up the inner walls of the shaft, and may engage an arrangement of pulleys at the top of the support structure. The cables may further continue down to a further arrangement of pulleys comprising a block-and-tackle. The counterweights may be suspended from the further arrangement of pulleys. 
     The pulleys may be arranged such that the falling counterweights accelerate the platform at a higher acceleration than that of the counterweights. In an embodiment, a block-and-tackle may connect the cables to the counterweights. A block-and-tackle may be provided as a subsystem of two or more blocks with the cable threaded between them. In one embodiment, each block may include a set of pulleys mounted on a single axle. In another embodiment, the blocks may be fiddle blocks. The mechanical advantage of the block-and-tackle may be constructed to provide acceleration in the useful range for a rocket (approximately 1 g to 5 g), and may be adjustable if future rockets can tolerate more than 5 g. The counterweights and pulley system may be sized to provide more than the maximum acceleration a rocket can tolerate, but in use the acceleration may be modulated using the braking system to limit the acceleration to the appropriate amount for a given rocket. 
     The platform may be large enough to accommodate a desired rocket. The platform may be adapted to support the weight of the rocket multiplied by the expected acceleration. For example, a 320,000 kg rocket that will be accelerated at 5 g must have a platform capable of supporting 1.6 million kilograms. 
     The surrounding structure may be embodied as two or more guide towers. In a pre-launch configuration, the guide towers may extend vertically from and surround the platform to define an interior shaft. The shaft may permit the platform to move freely vertically while constraining the horizontal movement of the platform. 
     It is contemplated that factors such as manufacturing defects, mechanical stress, temperature, wind, and other factors may create imperfections in the guide towers causing deviations of the guide towers from the straight-line vertical needed for a straight-line trajectory for the rocket. In an embodiment, the platform may be adapted to move laterally within the shaft to correct any deviations from the straight-line upward trajectory by pushing against an inner wall of one of the guide towers. In another embodiment, a movable base plate may be provided to correct deviations from the straight vertical path. 
     The rocket launch tower may include stability mechanisms for stabilizing the rocket to prevent loss of the rocket due to instability during launch. Stability mechanisms may include passive stability mechanisms and an active positioning subsystem. The stability mechanisms may include mechanisms to locate the platform horizontally within the surrounding structure. 
     In an embodiment, the inner wall of the guide towers may include guide rails. The platform may include guide wheels that engage with the guide rails to stabilize the platform during launch. The guide wheels may be connected to the platform body by springs to dampen deviations of the platform body caused by the motion of the guide wheels and imperfections in the guide towers. 
     The rocket launch tower may further include active stability mechanisms that control the lateral location of the platform. The platform may include platform linear actuators that may actuate to stabilize the platform body along the straight vertical path. The platform linear actuators may be controlled by the controller and may be actuated in response to imperfections measured by one or more sensors. In some embodiments, the platform includes a combination of passive stability mechanisms and active stability mechanisms. 
     The action of the active positioning subsystem acts to prevent deviations from a straight vertical path. It is understood that the guide rails of the guide towers may have various imperfections that may cause deviation of the platform from a straight vertical path as the platform moves along the guide rails. Imperfections may include local bending of the guide rails, leaning of the guide rails, etc. As the platform moves along the guide towers during launch, the active positioning system actuates platform linear actuators to keep the platform centered along the straight vertical path. 
     In some embodiments, the rocket launch tower may include functionality to permit the platform to be used to evaluate the straightness of the surrounding structure. Before launch, the platform may travel up the path of the platform and analyze the surrounding structure to measure imperfections in the surrounding structure, as may be present in the guide towers, the guide rails, etc. In order to measure imperfections, the platform may include various sensors to measure the imperfections. For example, in an embodiment, the platform may measure at various discrete points the needed amount of actuation required by the platform linear actuators to maintain the platform along the straight vertical path. The measured imperfections are recorded by the active positioning subsystem. During launch, the active positioning subsystem corrects for the imperfections dynamically as the platform moves up the surrounding structure. In other embodiments, an additional mechanism or system may be provided in addition to the platform to perform the evaluation of the straightness of the surrounding structure. 
     In some embodiments, the platform includes an attached base plate that may be passively or actively positioned relative to the platform. By providing a base plate, the stability mechanisms need not operate on the entire platform, but may specifically fine-tune the positioning of the rocket. Nevertheless, the platform may be passively positioned against the inner walls of the surrounding structure to provide additional stability. 
     For example, base plate linear actuators controlled by the controller may stabilize the base plate. In another embodiment, the platform may be stabilized by a passive stability mechanism. In the example shown, the platform is stabilized by springs. The base plate, however, may be stabilized by an active stability mechanism. In the example shown, the base plate is connected to the platform by base plate linear actuators. 
     In some embodiments, both passive and active stability mechanisms may be used in series. For example, the base plate is connected to the platform via springs that are in turn connected to base plate linear actuators. Similarly, the platform itself is connected to the guide wheels by springs, in addition to the springs connecting the base plate to the base plate linear actuators and, in turn, connecting the base plate to the platform. 
     In another embodiment, the stability mechanisms may include mechanisms to locate the base plate horizontally relative to the platform on which the base plate is supported. In embodiments with a base plate, the stability mechanisms may include hydraulic rams, linear actuators, levers, gear-driven mechanisms, etc. The stability mechanisms may also include passive mechanisms, which may be comprised of springs, torsion bars, or other such passive suspension elements. 
     In an embodiment, the stability mechanisms may include a braking system. The braking system serves to control the vertical speed of the platform and stop the platform after the rocket has left the platform. The braking system may include traditional brake calipers attached to the platform to brake the platform by applying friction to the guide rails or other, separate and parallel, braking rails. The active positioning subsystem may use the braking system to limit the acceleration applied to the rocket to levels appropriate for the rocket and its payload. In other embodiments, the braking system may be comprised of a braking calipers attached to the pulleys or to the cables. 
     In some embodiments, there may be an arrangement of adjustable support wires connected between the surrounding structure and the ground or other fixed object. The support wires may serve to keep the surrounding structure straight by applying tension to compensate for any bending or lack of straightness in the guide towers. The support wires may be connected to adjustable support wire motors to permit real-time adjustment. The support wire motors may be controlled by the controller to compensate for any lack of straightness in the towers including shifting and bending of the towers due to wind, thermal expansion, and other effects. The support wire motors may be linear actuators, electric motors, etc. Each support wire motor may be attached to a weighted block or structure embedded in or attached to the ground. 
     Adjustment using the support wires may proceed as follows: the controller detects any lack of straightness in the rocket launch tower using the sensors. For example, imagine that the rocket launch tower is found to be leaning to the left (e.g., the top of the rocket launch tower is too far to the left from the perspective of a viewer in front of the rocket launch tower). In this case, the right support wire motors would be adjusted to increase the tension on the right support wire, and the left support wire motors connected to the left support wire would be adjusted to decrease the tension on the left support wire, thereby pulling the tower back into a vertical position. Although the rocket launch tower is shown as having two support wires, in other embodiments, the rocket launch tower may include any number of support wires at varying positions around the rocket launch tower, and at varying heights up and down the rocket launch tower, as will be understood by one of ordinary skill in the art from the examples provided herein. 
     In an embodiment, the rocket launch tower may include an active positioning system for managing the rocket launch tower to stabilize the rocket during ascent. As shown, the active positioning system may include: the controller, one or more sensors, a main memory including instructions for stabilizing the rocket, and one or more active stability mechanisms, such as: platform linear actuators, base plate linear actuators, the braking system, and adjustable support wire motors. The sensors may include sensors that measure: the vertical acceleration of the platform, the vertical speed of the platform, the vertical position of the platform, the horizontal acceleration of the platform, the horizontal speed of the platform, the horizontal position of the platform, the tilt of the platform, the horizontal acceleration of the base plate, the horizontal speed of the base plate, the horizontal position of the base plate, the tilt of the base plate, the acceleration of the cables, the speed of the cables, the rotational acceleration of the pulleys, the rotational speed of the pulleys, etc. 
     The active positioning subsystem may be programmed to attempt to maintain certain movement of the platform. Typically this will involve a certain rate of acceleration depending on the capability of the rocket as well as maintaining ascent of the rocket on the straight vertical path. The active positioning subsystem may manage the rate of acceleration by modulating the braking system (for example, if the platform exceeds the requested acceleration it will apply braking, if the platform fails to reach the required acceleration it will reduce braking). Additionally, if the sensor and active positioning subsystem detects that the platform is beginning to tilt (for example, one side of the platform is moving upward more quickly than the other), the active positioning subsystem may apply additional braking on the too-high side, while reducing braking on the too-low side. Finally, the active positioning subsystem may adjust the active positioning system when it detects a lateral movement of the platform such that the platform or base plate moves in a straight vertical line. 
     In an embodiment, a rocket launch tower includes: a vertical support structure including two or more guide towers defining a vertical shaft between the two or more guide towers, each guide tower including one or more pulleys engaging one or more cables; a platform located within the vertical shaft and connected to the one or more cables; a drive mechanism that applies a force to the one or more cables to accelerate the platform along a trajectory within the vertical shaft; one or more sensors collecting data regarding the position of the platform along the trajectory within the vertical shaft and communicating the platform position data to a controller, the controller in communication with an acceleration control system including one or more brakes acting on the platform; wherein, the controller compares the platform position data received from the sensors to an intended platform acceleration and in response to receipt of platform position data indicating the platform acceleration has deviated from the intended platform acceleration, the controller causes the acceleration control system to actively correct the platform acceleration towards the intended platform acceleration. 
     In some embodiments, the drive mechanism includes one or more counterweights connected to the one or more cables by a block-and-tackle. Additionally, in some embodiments, the controller is also in communication with an active positioning system including the one or more brakes, further wherein, in response to receipt of platform position data indicating the platform trajectory has deviated from the intended platform trajectory, the controller causes the active positioning system to actively correct the platform trajectory towards the intended platform trajectory. Additionally, in some embodiments, the active positioning system further includes one or more linear actuators. 
     In some embodiments, each guide tower includes one or more guide rails, the platform includes two or more guide wheels, each of the guide wheels engages one of the one or more guide rails, and the active positioning system includes one or more linear actuators connecting the platform to the guide wheels. 
     In some embodiments, the rocket launch tower further includes a base plate, wherein the base plate includes one or more wheels, and the one or more wheels engage the platform. Additionally, in some embodiments, the base plate is connected to the platform by one or more linear actuators. Moreover, in some embodiments, a spring connects the linear actuator of the base plate to the platform. 
     In some embodiments, each guide tower includes one or more guide rails, the platform includes two or more guide wheels, each guide wheels engages one of the guide rails, each guide wheel is connected to the platform by a linear actuator, each linear actuator includes a sensor to measure the amount of actuation, wherein the controller is adapted to: receive from each sensor, during a pre-launch test, a plurality of measurements, taken at a plurality of points along the shaft, of the amount of actuation sufficient to maintain the platform trajectory along a straight vertical path; direct each actuator, during a launch, to actuate at each point along the shaft in accordance with the amount of actuation sufficient to maintain the platform trajectory along a straight vertical path. 
     In some embodiments, each guide tower includes one or more guide rails along the vertical shaft, the platform includes two or more guide wheels, and each guide wheels engages one of the one or more guide rails. Additionally, in some embodiments, each guide wheel is connected to the platform by a spring. 
     In some embodiments, the rocket launch tower further includes a base plate, wherein the base plate includes one or more wheels, each wheel engages the platform, and the base plate is laterally connected to the platform by one or more springs. 
     In some embodiments, each guide tower includes one or more guide rails along the shaft, the platform includes two or more guide wheels, the two or more guide wheels engage the one or more guide rails, the platform includes a base plate, and the base plate includes one or more wheels that engage the platform. 
     In some embodiments, the one or more brakes are connected to one of the vertical support structure or the platform, and the brakes, when activated by the controller, apply a braking force to one of: the one our more counterweights, the one or more cables, the one or more pulleys, and the platform. 
     In some embodiments, the one or more sensors include a straightness sensor attached to each guide tower detecting deviations of the guide tower from vertical straightness, the active positioning system further includes one or more support wires connected to the support structure, each of the support wires is connected to one or more tightening motors controlled by the controller, wherein the controller causes the one or more tightening motors to adjust the tension of the one or more support wires when the controller detects a deviation of one of the guide towers from vertical straightness. 
     An object of the invention is to provide a solution to find a cheap and reliable way to apply ground-based power to rocket launches. 
     Another object of the invention is to provide a solution to increase the payload capacity of existing rockets with a simple technological improvement over existing technology. 
     A further object of the invention is to reduce limitations on testing large rocket components. Rocket designers are currently limited in their ability to test large rocket components. The only way to subject the structure and components of a rocket to the loads imparted on it by launch and ascent is to launch the rocket. This is failure-prone (any major failure during flight results in destruction of the rocket) and rarely involves the ability to inspect the components after flight (most rockets, and certain components of all rockets) are non-recoverable (lost in space, destroyed in re-entry, damaged or destroyed on impact with the sea or the ground, etc.) 
     An advantage of the invention is that it provides a relatively inexpensive, reusable, and reliable way to increase the payload capacity of existing rockets. 
     A further advantage of the invention is that it provides a mechanism to reproduce the acceleration of a flying rocket in a non-destructive and repeatable fashion. The invention can simply subject a test article to the appropriate acceleration and then brake to a stop before the test article exits the top of the structure. The platform can then be lowered back to the ground and the test article inspected. This feature of the invention will improve rocket reliability through component testing and should allow rocket designers to produce more efficient rockets by removing the tendency to over-design a component that cannot otherwise be sufficiently tested. Rocket designers are currently limited in their ability to test large rocket components. The only way to subject the structure and components of a rocket to the loads imparted on it by launch and ascent is to launch the rocket. This is failure-prone (any major failure during flight results in destruction of the rocket) and rarely involves the ability to inspect the components after flight (most rockets, and certain components of all rockets) are non-recoverable (lost in space, destroyed in re-entry, damaged or destroyed on impact with the sea or the ground, etc.) This feature of the invention will improve rocket reliability through component testing and should allow rocket designers to produce more efficient rockets by removing the tendency to over-design a component that cannot otherwise be sufficiently tested. 
     Additional objects, advantages and novel features of the examples will be set forth in part in the description which follows, and in part will become apparent to those skilled in the art upon examination of the following description and the accompanying drawings or may be learned by production or operation of the examples. The objects and advantages of the concepts may be realized and attained by means of the methodologies, instrumentalities and combinations particularly pointed out in the appended claims. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The drawing figures depict one or more implementations in accord with the present concepts, by way of example only, not by way of limitations. In the figures, like reference numerals refer to the same or similar elements. 
         FIG. 1   a  is a front perspective view of an example rocket launch tower. 
         FIG. 1   b  is a perspective view of an example rocket launch tower. 
         FIG. 2   a  illustrates a cross-sectional view of the rocket launch platform showing a platform including springs as passive stability mechanisms. 
         FIG. 2   b  illustrates a cross-sectional view of the rocket launch platform showing a platform including linear actuators as active stability mechanisms. 
         FIG. 2   c  illustrates a cross-sectional view of the rocket launch platform showing a platform including springs as passive stability mechanisms and linear actuators as active stability mechanisms. 
         FIG. 3  illustrates the corrective action of the active positioning subsystem in positioning the platform along a straight vertical path. 
         FIG. 4   a  illustrates an embodiment of the platform of the rocket launch tower including an attached base plate including linear actuators as active stability mechanisms for the base plate. 
         FIG. 4   b  illustrates an embodiment of the platform including an attached base plate including springs as passive stability mechanisms for the platform and linear actuators as active stability mechanisms for the base plate. 
         FIG. 4   c  illustrates an embodiment of the platform including an attached base plate including springs as passive stability mechanisms and linear actuators as active stability mechanisms for the base plate. 
         FIG. 4   d  illustrates an embodiment of the platform including an attached base plate including springs as passive stability mechanisms and linear actuators as active stability mechanisms for the base plate, and including springs as passive stability mechanisms for the platform. 
         FIG. 5  illustrates an embodiment of the rocket launch tower including adjustable support wires and brakes. 
         FIG. 6  is a schematic diagram illustrating the active positioning system of the rocket launch tower. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       FIGS. 1   a  and  1   b  illustrates an embodiment of a rocket launch tower  10 . The rocket launch tower  10  includes a platform  20  that supports a rocket  30 . In use, the rocket launch tower  10  launches the rocket  30  from the upward-moving platform  20  thereby imparting energy into the rocket  30  before or in conjunction with the rocket  30  using its own propellant. 
     The platform  20  may be connected to cables  50  to provide the upward force during launch. The cables  50  may, in turn, connect the platform  20  to an arrangement of counterweights  70  via a pulley system. During launch, the counterweights  70  are allowed to fall, accelerating the cables  50  to cause upward movement of the platform  20 . A surrounding structure  40  guides the platform  50  and provides support to the cables  50  via pulleys  60  at the top of surrounding structure  40  that engage the cables  50 . As shown, the surrounding structure  40  may include one or more guide towers  130  that may guide the platform  20  during ascent. 
     As shown in  FIGS. 1   a  and  1   b , the cables  50  may be connected to the platform  20 , may run up the inner walls of the shaft  137 , and may engage an arrangement of pulleys  60  at the top of the support structure  40 . The cables  50  may further continue down to a further arrangement of pulleys  110  comprising a block-and-tackle  100 . The counterweights  70  may be suspended from the further arrangement of pulleys  110 . 
     The pulleys  60  may be arranged such that the falling counterweights  70  accelerate the platform  20  at a higher acceleration than that of the counterweights  70 . In an embodiment, a block-and-tackle  100  may connect the cables  50  to the counterweights  70 . A block-and-tackle  100  may be provided as a subsystem of two or more blocks  110  with the cable  50  threaded between them. In an embodiment, each block  110  may include a set of pulleys  60  mounted on a single axle. In an alternate embodiment, the blocks  110  are fiddle blocks. The mechanical advantage of the block-and-tackle  100  may be constructed to provide acceleration in the useful range for a rocket  30  (approximately 1 g to 5 g), and may be adjustable if future rockets  30  can tolerate more than 5 g. The counterweights  70  and pulleys  60  and the block-and-tackle  100  may be sized to provide more than the maximum acceleration a rocket  30  can tolerate, but in use the acceleration may be modulated using the braking system  90  to limit the acceleration to the appropriate amount for a given rocket  30 . 
     As shown in  FIGS. 1   a  and  1   b , the platform  20  may be large enough to accommodate a desired rocket  30 . The platform  20  may be adapted to support the weight of the rocket  30  multiplied by the expected acceleration. For example, a 320,000 kg rocket that will be accelerated at 5 g must have a platform capable of supporting 1.6 million kilograms. 
     The surrounding structure  40  may be embodied as two or more guide towers  130 . In a pre-launch configuration, the guide towers  130  may extend vertically from and surround the platform  20  to define an interior shaft  137 . The shaft  137  may permit the platform  20  to move freely vertically while constraining the horizontal movement of the platform  20 . 
     It is contemplated that factors such as manufacturing defects, mechanical stress, temperature, wind, and other factors may create imperfections in the guide towers  130  causing deviations of the guide towers  130  from the straight-line vertical needed for a straight-line trajectory for the rocket  30 . In an embodiment, the platform  20  may be adapted to move laterally within the shaft  137  to correct any deviations from the straight-line upward trajectory by pushing against an inner wall  135  of one of the guide towers  130 . In another embodiment, a movable base plate  140  may be provided to correct deviations from the straight vertical path  198  ( FIG. 3 ). 
     The rocket launch tower  10  may include stability mechanisms  80 ,  85  for stabilizing the rocket  30  to prevent loss of the rocket  30  due to instability during launch. Stability mechanisms  80 ,  85  may include passive stability mechanisms  80  and active stability mechanisms  85  that operate as part of an active positioning subsystem  200 . The stability mechanisms  80 ,  85  may include mechanisms to locate the platform  20  horizontally within the surrounding structure  40 . 
       FIG. 2   a  illustrates examples of passive stability mechanisms  80 . As shown in  FIG. 2   a , the inner wall  135  of the guide towers  130  may include guide rails  160 . The platform  20  may include guide wheels  170  that engage with the guide rails  160  to stabilize the platform  20  during launch. The guide wheels  170  may be connected to the platform body  25  by springs  180  to dampen deviations of the platform body  25  caused by the motion of the guide wheels  170  and imperfections in the guide towers  130 . 
     Turning to  FIG. 2   b , the rocket launch tower  10  may further include active stability mechanisms  85  that control the lateral location of the platform  20 . As shown, the platform  20  may include platform linear actuators  220  that may actuate to stabilize the platform body  25  along the straight vertical path  198 . The platform linear actuators  220  may be controlled by the controller  260  and may be actuated in response to imperfections  190 ,  191  ( FIG. 3 ) measured by one or more sensors  210 . 
     In some embodiments, the platform  20  includes a combination of passive stability mechanism  80  and active stability mechanisms  85  attached to a platform body  25  for supporting the rocket  30  that comprises the bulk of the platform  20 . As shown in  FIG. 2   c , in some embodiments, a platform  20  may include both platform linear actuators  220  and springs  180 . 
     Turning to  FIG. 3 , an illustration of the action of the active positioning subsystem  200  is shown. Specifically,  FIG. 3  illustrates the platform  20  at various discrete points  192 ,  193 ,  194 ,  195 ,  196  at various timesteps during a launch. As shown, the guide rails  160  of the guide towers  130  may have various imperfections  190 ,  191  (exaggerated here for illustrative purposes) that may cause deviation of the platform  20  from a straight vertical path  198  as the platform  20  moves along the guide rails. The imperfections  190 ,  191  shown include local bending of the guide rails  160  and a slight leaning of one of the guide rail  160 . As the platform  20  moves along the guide towers  130  during launch, the active positioning system  200  actuates the platform linear actuators  220  to keep the platform  20  centered along the straight vertical path  198 . 
     In some embodiments, the rocket launch tower  10  may include functionality to permit the platform  20  to be used evaluate the straightness of the surrounding structure  40 . Before launch, the platform  20  may travel up the path of the platform and analyze the surrounding structure  40  to measure imperfections  190 ,  191  in the surrounding structure  40 , as may be present in the guide towers  130 , the guide rails  160 , etc. In order to measure imperfections  190 ,  191 , the platform  20  may include various sensors  210  to measure the imperfections  190 ,  191 . For example, in an embodiment, the platform  20  may measure at various discrete points  192 ,  193 ,  194 ,  195 ,  196  the needed amount of actuation required by the platform linear actuators  220  to maintain the platform  20  along the straight vertical path  198 . The measured imperfections  190 ,  191  are recorded by the active positioning subsystem  200 . During launch, the active positioning subsystem  200  corrects for the imperfections  190 ,  191  dynamically as the platform  20  moves up the surrounding structure  40 . In other embodiments, an additional mechanism or system may be provided in addition to the platform  20  to perform the evaluation of the straightness of the surrounding structure  40 . 
     Turning to  FIGS. 4   a - 4   d , another embodiment of the platform  20  is shown. In the embodiment, the platform  20  includes an attached base plate  140  for supporting the rocket  30  that may be passively or actively positioned relative to the platform body  25 . By providing a base plate  140 , the stability mechanisms  80 ,  85  need not operate on the entire platform  20 , but may specifically fine-tune the positioning of the rocket  30 . Nevertheless, as shown in  FIGS. 4   b  and  4   d , the platform  20  may be passively positioned against the inner walls  135  of the surrounding structure  40  to provide additional stability. 
     For example, as shown in  FIG. 4   a , base plate linear actuators  230  controlled by the controller  260  may stabilize the base plate  140 . In another embodiment shown in  FIG. 4   b , the platform body  25  may be stabilized by a passive stability mechanism  80 . In the example shown, the platform body  25  is stabilized by springs  180 . The base plate  140 , however, may be stabilized by an active stability mechanism  85 . In the example shown, the base plate is connected to the platform body  25  by base plate linear actuators  230 . 
     In some embodiments, both passive stability mechanisms  80  and active stability mechanisms  85  may be used in series. For example, as shown in  FIG. 4   c , the base plate  140  is connected to the platform body  25  via springs  180  that are in turn connected to base plate linear actuators  230 . Similarly, in  FIG. 4   d , the platform body  25  itself is connected to the guide wheels  170  by springs  180 , in addition to the springs  180  connecting the base plate  140  to the base plate linear actuators  230  and, in turn, connecting the base plate  140  to the platform body  25 . 
     In another embodiment, the stability mechanisms  80 ,  85  may include mechanisms to locate the base plate  140  horizontally relative to the platform body  25  on which the base plate  140  is supported. In embodiments with a base plate  140 , the stability mechanisms  80 ,  85  may include hydraulic rams, linear actuators, levers, gear-driven mechanisms, etc. The stability mechanisms  80 ,  85  may also include passive mechanisms, which may be comprised of springs, torsion bars, or other such passive suspension elements. 
     In an embodiment, the active stability mechanisms  85  may include a braking system  90 , as shown in  FIG. 5 . The braking system  90  serves to control the vertical speed of the platform  20  and stop the platform  20  after the rocket  30  has left the platform  20 . The braking system  90  may include traditional brake calipers  250  attached to the platform  20  to brake the platform  20  by applying friction to the guide rails  160  or other, separate and parallel, braking rails. In other embodiments, the braking system  90  may be comprised of a braking calipers  250  attached to the pulleys  60 , blocks  110 , or to the cables  50 . 
     Additionally, in an embodiment, the rocket launch tower  10  may include an acceleration control system to limit the acceleration applied to the rocket  30  to levels appropriate for the rocket  30  and its payload. The acceleration control system may include the braking system  90 , the controller  260 , and sensors  210  to measure the vertical acceleration of the platform  20 . During launch, the controller  260  compares the platform position data received from the sensors  210  to an intended platform acceleration and in response to receipt of platform position data indicating the platform acceleration has deviated from the intended platform acceleration, the controller  260  causes the acceleration control system to actively correct the platform acceleration towards the intended platform acceleration. 
     As further shown in the embodiment of  FIG. 5 , there may be an arrangement of adjustable support wires  270  connected between the surrounding structure  40  and the ground or other fixed object. The support wires  270  may serve to keep the surrounding structure  40  straight by applying tension to compensate for any bending or lack of straightness in the guide towers  130 . The support wires  270  may be connected to adjustable support wire motors  280  to permit real-time adjustment. The motors  280  may be firmly held to the ground by weight blocks  285  or other supports necessary to hold the support wires  270  firm. The support wire motors  280  may be controlled by the controller  260  to compensate for any lack of straightness in the towers including shifting and bending of the towers due to wind, thermal expansion, and other effects. The support wire motors  280  may be linear actuators, electric motors, etc. Each support wire motor  280  may be attached to a weighted block or structure embedded in or attached to the ground. 
     Adjustment using the support wires  270  may proceed as follows: the controller  260  detects any lack of straightness in the rocket launch tower  10  using the sensors  210 . For example, imagine that the rocket launch tower  10  is found to be leaning to the left (e.g., the top of the rocket launch tower  10  is too far to the left from the perspective of a viewer in front of the rocket launch tower  10 ). In this case, the right support wire motors  280  would be adjusted to increase the tension on the right support wire  270 , and the left support wire motors  280  connected to the left support wire  270  would be adjusted to decrease the tension on the left support wire  270 , thereby pulling the tower back into a vertical position. Although the rocket launch tower  10  is shown as having two support wires  270 , in other embodiments, the rocket launch tower  10  may include any number of support wires  270  at varying positions around the rocket launch tower  10 , and at varying heights up and down the rocket launch tower  10 , as will be understood by one of ordinary skill in the art from the examples provided herein. 
     As shown in  FIG. 6 , the rocket launch tower  10  may include an active positioning system  200  for managing the rocket launch tower  10  to stabilize the rocket  30  during ascent. As shown, the active positioning system may include: the controller  260 , one or more sensors  210 , a main memory  290  including instructions for stabilizing the rocket  30 , and one or more active stability mechanisms  85 , such as: platform linear actuators  220 , base plate linear actuators  230 , the braking system  90 , and adjustable support wire motors  280 . The sensors  210  may include sensors  210  that measure: the vertical acceleration of the platform  20 , the vertical speed of the platform  20 , the vertical position of the platform  20 , the horizontal acceleration of the platform  20 , the horizontal speed of the platform  20 , the horizontal position of the platform  20 , the tilt of the platform  20 , the horizontal acceleration of the base plate  140 , the horizontal speed of the base plate  140 , the horizontal position of the base plate  140 , the tilt of the base plate  140 , the acceleration of the cables  50 , the speed of the cables  50 , the rotational acceleration of the pulleys  60 , the rotational speed of the pulleys  60 , etc. 
     The active positioning subsystem  200  may be programmed to attempt to maintain certain movement of the platform  20 . Typically this will involve a certain rate of acceleration depending on the capability of the rocket  30  as well as maintaining ascent of the rocket  30  on the straight vertical path  198 . The active positioning subsystem  200  may manage the rate of acceleration by modulating the braking system  90  (for example, if the platform  20  exceeds the requested acceleration it will apply braking, if the platform  20  fails to reach the required acceleration it will reduce braking). Additionally, if the sensor  210  and active positioning subsystem  200  detects that the platform  20  is beginning to tilt (for example, one side of the platform  20  is moving upward more quickly than the other), the active positioning subsystem  200  may apply additional braking on the too-high side, while reducing braking on the too-low side. Finally, the active positioning subsystem  200  may adjust the active stability mechanisms  85  of the active positioning system  200  when it detects a lateral movement of the platform  20  such that the platform  20  or the base plate  140  moves away from the straight vertical path  198 . 
     As described, a controller  260  controls aspects of the rocket launch tower  10  described herein. The controller  260  may be embodied in one or more controllers  260  that may be adapted run a variety of application programs, access and store data, including accessing and storing data in associated database (which may be embodied in one or more databases), and enable one or more interactions with the other components of the rocket launch tower  10 . Typically, the one or more controllers  260  are embodied in one or more programmable data processing devices. The hardware elements, operating systems, and programming languages of such devices are conventional in nature, and it is presumed that those skilled in the art are adequately familiar therewith. 
     For example, the one or more controllers  260  may be a PC based implementation of a central control processing system utilizing a central processing unit (CPU), memories  290  and an interconnect bus  300 . The CPU may contain a single microprocessor, or it may contain a plurality of microprocessors for configuring the CPU as a multi-processor system. The memories  290  include a main memory  290 , such as a dynamic random access memory  290  (DRAM) and cache, as well as a read only memory  290 , such as a PROM, EPROM, FLASH-EPROM, or the like. The system may also include any form of volatile or non-volatile memory  290 . In operation, the main memory  290  stores at least portions of instructions for execution by the CPU and data for processing in accord with the executed instructions. 
     The one or more controllers  260  may also include one or more input/output interfaces for communications with one or more processing systems. Although not shown, one or more such interfaces may enable communications via a network, e.g., to enable sending and receiving instructions electronically. The communication links may be wired or wireless. 
     The one or more controllers  260  may further include appropriate input/output ports for interconnection with one or more output displays and one or more input mechanisms serving as one or more user interfaces for the controller  260 . For example, the one or more controllers  260  may include a graphics subsystem to drive digital displays. The links of the peripherals to the system may be wired connections or use wireless communications. 
     Although summarized above as a PC-type implementation, those skilled in the art will recognize that the one or more controllers  260  also encompasses systems such as host computers, servers, workstations, network terminals, and the like. In fact, the use of the term controller  260  is intended to represent a broad category of components that are well known in the art. 
     Aspects of the systems and methods provided herein encompass hardware and software for controlling the relevant functions. Software may take the form of code or executable instructions for causing a controller  260  or other programmable equipment to perform the relevant steps, where the code or instructions are carried by or otherwise embodied in a medium readable by the controller  260  or other machine. Instructions or code for implementing such operations may be in the form of computer instruction in any form (e.g., source code, object code, interpreted code, etc.) stored in or carried by any tangible readable medium. 
     As used herein, terms such as computer or machine “readable medium” refer to any medium that participates in providing instructions to a processor for execution. Such a medium may take many forms. Non-volatile storage media include, for example, optical or magnetic disks, such as any of the storage devices in any computer(s) shown in the drawings. Volatile storage media include dynamic memory, such as main memory  290  of such a computer platform. Common forms of computer-readable media therefore include for example: a floppy disk, a flexible disk, hard disk, magnetic tape, any other magnetic medium, a CD-ROM, DVD, any other optical medium, punch cards paper tape, any other physical medium with patterns of holes, a RAM, a PROM and EPROM, a FLASH-EPROM, any other memory chip or cartridge, or any other medium from which a computer can read programming code and/or data. Many of these forms of computer readable media may be involved in carrying one or more sequences of one or more instructions to a processor for execution. 
     It should be noted that various changes and modifications to the presently preferred embodiments described herein will be apparent to those skilled in the art. Such changes and modifications may be made without departing from the spirit and scope of the present invention and without diminishing its attendant advantages.