This invention is generally related to a rotating mass propulsion system and specifically related to a rotating mass propulsion system for low or zero gravity satellites and spacecrafts.
There are approximately 2,300 satellites in orbit around the earth today. Military, scientific, and communication satellites are vital to the functioning of many industrialized nations. While only a few countries have the capabilities to launch their own satellites, companies such as SpaceX and United Launch Alliance have privatized space launches and made it available for purchase. Thanks to the commoditization of space flight, even the smallest of nations can afford to place a satellite in orbit. Countries such as Ghana have launched their own satellite as a mark of national pride and also to cut the cost of buying satellite data from other countries. Consequently, geosynchronous orbit has become quite crowded.
Satellites are a key component of global telecommunication. About 60 percent of all satellites play some role in communication. Communication satellites are generally in geostationary orbit above the earth. Other satellites, such as remote sensing satellite, may need to be repositioned to cover another area of the globe. Satellites such as Global Positioning System (GPS) satellites in lower earth orbit may need to be constantly repositioned due to orbital decay. Some satellites may also need to be moved to avoid collision with other satellites or space debris.
In addition to active satellites, there are many defunct satellites that were never safely decommissioned. Oftentimes, these old satellites are left to continue in their stable orbit instead of moving them to a decaying orbit. These satellites are sometimes used as targets for missile tests resulting in even more space debris. NASA actively tracks more than 500,000 pieces of space debris in orbit around the Earth. Some are naturally occurring such as meteoroids and other are manmade. Some of these pieces of space debris may travel at speed of 17,500 miles per hour. In order to avoid catastrophic collision with space debris, oftentimes the spacecraft may need to be moved out of the path of collision. A reliable, efficient, and economical means of propulsion is thus highly sought after by satellite manufacturers.
Satellites traditionally move by means of propellant thrusters. Monopropellant hydrazine thruster may be used for attitude, trajectory and orbit control of small and mid-size satellites and spacecraft. Thrust is generated when a control valve is commanded to open causing the propellant hydrazine to be fed to the thrust chamber where a decomposition reaction takes place within a catalyst bed. While regarded as dependable and low-cost, propellant thrusters suffer from at least one obvious flaw. Eventually, the propellant runs out. Large fuel tanks are not feasible due to the cost to weight ratio of getting a satellite into orbit. Thus, while dependable, propellant thrusters have a finite amount of fuel and cannot provide thrust over a long period of time especially if multiple maneuvers must be taken frequently.
Currently, the slowest form of propulsion, and the most fuel-efficient, is the ion engine or ion drive. An ion thruster or ion drive is a form of electric propulsion used primarily for spacecraft propulsion. It creates thrust by accelerating positive ions with electricity. An ion thruster ionizes a neutral gas by extracting some electrons out of atoms, creating a cloud of positive ions. Ion thrusters have demonstrated fuel efficiencies of over 90 percent as compared to the 35 percent efficiency of a chemical fuel rocket. Although efficient, ion thrusters still require some fuel in the form of a neutral gas. Additionally, ion thrusters are still relatively cutting-edge technology and thus expensive.
What is needed is a means for satellite locomotion that can replenished in orbit and is relatively inexpensive to produce.
An aspect of this invention is generally related to a method and apparatus of a rotating mass propulsion system for use in zero or low gravity satellites and spacecrafts where atmospheric drag is not a relevant factor in propulsion.
Embodiments of the invention comprise one or more of rotating masses that are generally circular or disk shaped. Preferably, more than one rotating mass is used, as using only one rotating mass can twist the spacecraft. Multiple rotating masses can be equally spaced about the circumference of a circle, the circle being on a reference plane, such that the thrust at each rotating mass is balanced by one or more of the other rotating mass on the circumference of the circle. The axis of rotation of the rotating mass would be parallel to the reference plane. It would be beneficial to have the center of rotation of each rotating mass lie on the same plane. Actuation of the rotating mass causes thrust perpendicular to the plane. Varying the speed and direction of the rotation can vary the amount of net thrust as well as cause torque about the center of the circle allowing for limited directional control of the net thrust produced.
This summary was provided to efficiently present the general concept of the invention and should not be interpreted as limiting the scope of the claims.
Method and apparatus to provide a rotating mass propulsion system are described below. In the following description, numerous specific details are set forth. However, it is understood that embodiments of the invention may be practiced without these specific details. In other instances, well-known components, structures, and techniques have not been shown in detail in order to not obscure the understanding of this description.
Reference in the specification to “one embodiment” or “an embodiment” means that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment of the invention. The appearances of the phrase “in one embodiment” in various places in the specification do not necessarily all refer to the same embodiment.
The word spacecraft is used in this Application to denote a vehicle or device designed for travel or operate outside the Earth's atmosphere, whereas a satellite is an object that orbits the Earth, the moon, or another celestial body. The term “astromotive” is used in this Application in conjunction with “device” to refer to a personal device for moving a person or persons in low or zero gravity conditions.
For thousands of years humankind has looked to the stars, but only relatively recently have we been able to reach beyond Earth's gravity. The untapped potential for space exploration and exploitation are enormous, but the cost of researching and developing viable space programs once limited the playing field to a handful of rich and technologically advanced nations.
With the rise of companies such as SpaceX, Virgin Galactic, Blue Origin, Sierra Nevada, etc., space exploration has finally become commercialized and not restricted to only wealthy industrialized countries with their geo-political agendas. Although these innovative companies have opened the playing field, there remain a prohibitive cost associated with sending objects into space. Launch costs are still in the millions of U.S. dollars, thus making satellites and zero-gravity research not quite available to all.
The cost of launching a satellite varies depending on the mass of the satellite, the orbital altitude, and the orbital inclination of the final satellite orbit. The advent of reusable launch systems has dropped the price of a launch in the range of 2,000-30,000 USD per kilogram. As total cost of placing a satellite or spacecraft into orbit is heavily dependent on the mass of the satellite, it is advantageous to reduce the mass of the propulsion system in a satellite or spacecraft being launched. One of method of reducing satellite mass would be to use a propulsion system that does not need a chemical fuel source.
A propulsion system that does not rely on chemical fuels can utilize a linear force generated by a rotating mass. Ideally the rotating mass would be very dense and in the shape of a torus. The rotating mass can be any material composition—solid, liquid, or gas—preferably a liquid. Using a fluid allows for maximum available volume in the torus for the rotating mass. A liquid also has the inherent ability to be self-balancing when rotating.
Embodiments of the invention use available components and materials to create a functioning engine utilizing the underlying principles of the invention. For example, in some embodiments, eight discs are used instead of a torus shaped rotating mass. The disks are effectively eight thin “slices” of the entire rotating “torus” mass. The axis of rotation of each disk is parallel to a reference plane. The rotation of the “torus” as a whole would be perpendicular to the reference plane such that the rotating mass is through the center of the “torus”. Referring briefly to
Embodiments of the invention use batteries to power a motor which in turn rotate a mass. Rotating masses are preferably placed on the same plane and equally spaced on that plane, e.g. about the circumference of a circle. As weight is of concern, a light weight battery would be preferred. A rechargeable battery connected to a solar array would also be capable of extending the life of the battery and thus the productive life of the satellite. Using a battery as the power source for satellite propulsion is preferred because it saves on the cost of translating a fuel source into orbit. Furthermore, a battery is a renewable source of energy that can extend the useful life of the propulsion system and satellite. Batteries can be recharged with solar energy, thus avoiding the need for liquid or solid refueling.
The force produced by the rotating mass is very slight, in the order of 10 gram of force (thrust) per 4 amps of electricity. Within the earth's atmosphere, thrust produced by a rotating mass propulsion system would not be a feasible means of propelling a craft. However, in space, without air resistance or gravity, even a small force would be sufficient to slowly propel a spacecraft.
An exemplary embodiment of the invention is illustrated in
In
As illustrated in one embodiment of the invention, the rotating mass propulsion system comprises four rotating masses 112A-D. Rotating masses 112A-D can be disk shaped. The discs could be tapered, e.g. thin in the center and thicker at the circumference, perhaps even tube shaped at the circumference. Tapering the disk from center to circumference provides more mass efficient percentage effect.
Rotating masses 112A-D are located on the same circular plane, in this case at the aft end 116 of the satellite 100. Ideally, the rotating masses should be oriented in the same direction. For example, in
Each rotating mass 112A-D, provides a vectored force. By placing each rotating mass 112A-D in a planar circle equidistant from each other around the circumference of said circle, the vectored force of each rotating mass 112A-D are balanced to provide thrust in one direction with minimal torque to the satellite 100. In embodiments of the invention with multiple rotating masses or discs, pairs of disks should rotate in opposition. The disks should be substantially aligned 180 degrees, with no tilt, to eliminate a “torque twisting” effect applied to the engine frame.
Rotating masses 112A-D can be rotated by one or more motors. The motors that spin the rotating mass 112A-D are not illustrated in
Electric motors can be utilized to spin the rotating masses. An electric motor is preferred over combustion engines due to the lack of oxygen in the vacuum of space among other reasons. Combustion engines would also require fuel that is not easily or economically replaceable. In the simplest configuration, one electric motor is coupled to one rotating mass. A one-to-one ratio of electric motor to rotating mass allows for variable independent rotation of each rotating mass for directional control. When all of the rotating masses 112A-D are spun in the same direction and the same rate of spin, the thrust is substantially in the same direction. Varying the spin rate of one rotating mass 112A-D can cause the thrust to become unbalanced. Increasing the spin rate of rotating mass 112C for example can cause the satellite to steer upwards. “Upwards” of course being a relative term, for the purpose of this application “upwards” is towards the top of the page in
The embodiment of the invention, described above and illustrated in
The force generated by each rotating mass 112 can be generally expressed by the following equations.
The motors spinning rotating masses 112A-D can be powered by a battery 114 which in turn is recharged by solar panels 106 and 108. Electric motors are preferred because they do not need to combust solid or liquid fuel. Electric motors, however, need a source of electricity to provide power to the motors. Battery 114 can provide a source of electricity that is rechargeable for thousands of recharge cycles, thus potentially extending the life of the satellite to dozens of years of use. Battery 114 can be of any type e.g. nickel cadmium, nickel metal hydride, lithium ion, etc. with preference to lighter more efficient batteries with more recharge cycles and greater energy density. In order to continuously provide electricity to the electric motors, battery 114 can be coupled to one or more solar collectors 106 and 108 that are preferably moveable to maximize solar energy collection.
The rotating mass 212 is illustrated in more detail in
In
In
Although the rotating mass propulsion units of
Referring now to
Certain specifications are hereby provided for the components described in
In the embodiment of the invention illustrated in
Each motor has a separate ESC to provide independent rotation speed control to each motor, thus providing variable thrust and a limited form of vector propulsion control. Control commands from a flight controller to the ESC's can be wired in parallel for thrust only. In embodiments of the invention, the ESC's are wired to a flight controller that determines speed for each motor by interpolation in order to steer the engine on a controlled flight vector.
In the embodiment illustrated in
An engine mount 500 may be used to secure the rotating mass propulsion system 400 of
Engine mount 500 can be mounted to the frame 528 of the spacecraft at each horizontal mounting point at the lower portion of the legs 524. A screw 526 or other method, e.g. welding, rivet, etc., of affixing the leg 524 to the frame 528 of a spacecraft can be used. Engine mount 500 can be formed of a light weight rigid material such as aluminum, stainless steel, or plastic. A factor in selecting the material of the engine mount 500 is of course the tensile strength needed to withstand the thrust generated by the rotating mass propulsion system. Engine mount material must be able to withstand the dynamic force exerted by the engine during operation as well as the mass of the engine unit. Engine mount 500 can also be mounted to any strong horizontal surface inside the skin of the spacecraft. It can be desirable to make engine mount 500 easily mountable and removeable to make each rotating mass propulsion unit modular. Astronauts, with limited tools, can remove, replace, or add modular rotating mass propulsion unit as needed during spacewalks.
Currently astronauts have no means of propulsion during spacewalks. Astronauts working outside the international space station wear a jet backpack known as SAFER. SAFER is equipped with very small thrusters that expel gas and propel an astronaut in the direction he or she wants to go. However, the SAFER system is for emergency only, in case the astronaut becomes untethered from the Space Station. The SAFER system is an emergency system and is not meant as an “astromotive” device.
Embodiments of the invention as previously described above have been primarily concerned with industrial applications for the invention. Satellites and other spacecrafts used by governments and industries could benefit greatly by using this invention. The invention, however is not limited to only industrial applications and is equally, if not more so, beneficial to personal and recreational use.
An astromotive device, i.e. a personal device for moving a person or persons in low or zero gravity conditions can have a massive impact on future non-industrial applications. The invention may be adapted for use in personal and recreational astromotive vehicles that would directly benefit humankind.
Although certain exemplary embodiments and methods have been described in some detail, for clarity of understanding and by way of example, it will be apparent from the foregoing disclosure to those skilled in the art that variations, modifications, changes, and adaptations of such embodiments and methods may be made without departing from the true spirit and scope of the invention. This disclosure contemplates other embodiments or purposes.
For example, it will be appreciated that one of ordinary skill in the art will be able to employ a number of corresponding alternative and equivalent structural details, such as equivalent ways of fastening, mounting, coupling, or engaging tool components, equivalent mechanisms for producing particular actuation motions, and equivalent mechanisms for delivering electrical energy. As another example, structural details from one embodiment may be combined with or utilized in other disclosed embodiments. Therefore, the above description should not be taken as limiting the scope of the invention which is defined by the appended claims.