Modular micropropulsion device and system

Abstract

A modular propulsion system includes an array of micromachined field effect electrostatic propulsion devices, each of which is an assembled micromachined device including an array of field effect electrostatic propulsion thrusters, a fuel container of propellant using passive plumbing, electronic power and command controls, with the array of devices disposed about and on a surface of a spacecraft for providing diverse propulsion needs.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 depicts a modular micropropulsion device.

FIG. 2 depicts a modular micropropulsion system.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

An embodiment of the invention is described with reference to the figures using reference designations as shown in the figures. Referring to FIG. 1, a modular micropropulsion device is preferably fashioned in the shape of a cube having on a top surface of electronics comprising a power converter, a data processor, a command decoder, a device transceiver, and a solar cell array. An exemplar solar cell in the solar cell array is designated as such. Also disposed on the top of the cube device is a thruster array for providing thrust. An exemplar thruster in the thruster array is designated as such. On opposing sides of the cube device are disposed a data transmitter antenna and a command receiver antenna. On the bottom of the cube are disposed data contacts, power contacts, and heat sink contacts. The cube is protected by a heat shield about the periphery of the cube. A battery is internally disposed in the cube device, preferably near the bottom of the cube device. Above the battery is disposed a fuel container for containing a propellant for use by the thruster array. The container is preferably temperature regulated using a heater. The fuel container includes passive plumbing, such as a wick, for moving the propellant toward the thruster array including the exemplar thruster for providing thrust. The propellant moves towards and to the thrusters by passive plumbing relying upon, for example, capillary action. The thruster array is an array of preferably like micromachined field effect electrostatic propulsion thrusters.

In operation, the solar cell array collects solar energy and provides power to charge the battery for reliable internal power supply to the power converter delivering power to the data processor, command decoder, and device transceiver, as well as the micromachined field effect electrostatic propulsion thruster array. The data processor is used for management operation of the command decoder and device transceiver for receiving commands and transmitting data respectively through the command receiver antenna and the data transmitter antenna. The data processor controls and monitors controlled thrusting action of the thruster array, and indicates the amount and time of thrust provided, and hence, the amount of remaining propellant in the fuel container. The propellant flows preferably by capillary forces to the thrusters. The propellant may be a gallium-based propellant. Power through the device is routed by electronic conducting traces not shown for convenience. While the thrusters are shown with the thruster array on the top of a cube, side placement of the thruster array can be realized for providing side thrusting as desired. The cube design is an exemplar one as other shapes could be used. Placement of antennas, solar cells, electronics, and thrusters can be disposed about the device in various configurations as desired.

The modular microthruster device is essentially an assembled microchip that can conveniently include electronic processors and command receiver chips or processors typically disposed on exterior locations, though internal dispostions may be desirable. The propellant container can be equipped with a heater, as needed, to keep the propellant liquid as environmental conditions require. The propellant wick is a passive propellant acquisition device, such as a screen, that can used as needed. The device shape, such as a cube, can be made on the order of one centimeter on the sides and can be bonded to appropriate spacecraft surface locations where ever directional thrust is desired. The thrust level of a device is determined by the number of microthrusters activated on the assembly face of the device as well as pulse modulation of an accelerating voltage from the power converter while the propellant amount and thus total impulse obtainable is determined by the quantity of propellant stored within the device. The modular shape of the devices is preferably cubical, but different volume and shapes of the device allow for a large range of accumulative thrust and total impulse capabilities distribution on the surfaces of the spacecraft. The modular shapes can be dictated by the most effective propellant wicking or other propellant acquisition means employed. The implementation of the modular device in a cube shape is illustrative only. There are many other possible packaging shapes, and sizes, with various internal details that can accomplish the same modular purpose.

Referring to FIGS. 1 and 2, the modular micropropulsion system includes a plurality of modular micropropulsion devices preferably aligned in a micropropulsion device array affixed to an exterior spacecraft surface. An exemplar micropropulsion device is designated as such. The system preferably includes a power bus for routing alternative power from a system battery and power supply to the power contacts of the device as power is needed and as an alternative source of power for the device array. The system preferably includes a heat sink bus for transferring waste heat from the device array through heat sink contacts of the device array to a system heat sink. The system preferably includes a data bus for routing command to and data from the device array through data contacts of the device array. The data can indicate the state of the device, including the amount of fuel used and the amount of remaining controlled thrust available from the device of the array of devices. As an alternative method of communication, a command and data transceiver can transmits command to and receive data from the device array using a system antenna communicating through the data transmitter antenna and command receiver antenna of the device array. Beyond solar power, device battery, or system power supply, power to the devices could also be delivered to the devices by electromagnetic propagation through power transmission from the system antenna and collected by the receiving antenna of the devices.

In operation, the system relies upon necessary communications, power supply, and thrusting in an array arrangement. The system has data and command communications through either hard-wire contacts or through electromagnetic propagation using antennas, or both. Power for operating the devices can be from solar cell energy collection or through the system power supply, or both. As more system thrust is desired at various locations of the spacecraft surface, the devices can be disposed in various numbers and at various locations as desired. The preferred form shows only one such arrangement in a square device in a rectangular array arrangement for an exemplar maximum packing densities on a portion of the surface of the spacecraft using the preferred cubical device shape. Further, the shape of an individual device need not necessarily be square as shown, but could also preferably be rectangular, hexangular, triangular, or otherwise to meet various design density and placement requirements about the spacecraft surface.

Micron-sized field effect electrostatic propulsion thrusters are made by micromachining and microchip assembly using conventional manufacturing techniques so that the propulsion thruster gaps are made in the order of micron-sizes and the cube in the order of centimeters. The micromachined field effect electrostatic propulsion thruster device can have any number of different implementation designs and configurations as desired or required. The modular device packaging enables lightweight thrusting in various configurations and in any amount of accumulated directional thrust, well suited for use on small spacecraft. When the total impulse required is much larger than that deliverable by one device for a propulsion application, the requirement can be met by bonding more of the devices to the surface of the spacecraft at appropriate locations desirable for attitude control and translation propulsion of the spacecraft.

The space propulsion systems use arrays of micromachined field effect electrostatic propulsion thruster devices each having an array of thrusters each having a micromachined micron-sized thruster gap to create very large ion accelerating fields with small applied voltages, resulting in thruster devices having a large specific impulse and large thrust simultaneously. The devices can be machined to be small and lightweight. The modularity of the system enables scalability to attain a very large range of thrusts and total impulses without redesigning, redeveloping, or re-testing each device in the array of devices. The ease of supplying power and communications to the devices, together with the complete flexibility of locations for the attained thrust, provides savings in time and man-hours leading to much more affordable spacecraft.

This modular system provides solutions to various propulsion requirements by providing high-accumulated thrust and high specific impulse simultaneously at very low weight and power requirement, using compact self-contained modular thruster devices that can be inexpensively mass-produced. The modular devices include means to deliver electrical power and propellant to the thruster array, and means to receive commands to control the thruster operation with passive plumbing fuel delivery. Coatings and shields can be used to regulate the thermal environment of the devices. Hard wires or antennas can be used in combination to provide power and commands to the devices from a remote or central system controller. Communications means, power delivery means, and fuel containers can be integrated into the modular devices that can then be glued or bonded to the spacecraft surface where needed. Plated wiring or other hard electrical contact means can be routed from the system controller to the devices disposed at various locations in an array on the surface of the spacecraft. A spacecraft surface can use several plated wiring runs so that the devices can be attached where desired on the surface, singly or in numbers, without any redesign of the devices. Power as well as commands also can be sent to the thruster devices via microwave beams from central system antennas to avoid the need for any wiring runs or hardwired contacts. The devices can have receiving antennas built in, plated on, or otherwise disposed as part of the devices. The spacecraft surface is used to support the devices in desired locations to meet specific thrusts needs about the spacecraft.

These modular devices can be attached to the spacecraft surface where ever needed to provide thrust as needed for spacecraft attitude control, or station keeping, or translation. Power and commands are provided along the spacecraft to and at those locations where thrust is known to be required, or, alternatively at many points where the thrust might eventually be required. Command and power delivery to various locations on the surface of the spacecraft can be provided by many wiring points or wiring runs that can be plated or bonded to the surface of the spacecraft in any array configuration. The devices can be made in any desired shape, using wired or wireless transmission of power, command, and data communications. The micromachined field effect electrostatic propulsion thruster devices can be adapted to meet a wide range of spacecraft propulsion needs well suited for small spacecraft, or in aggregation to larger spacecraft. Those skilled in the art can make enhancements, improvements, and modifications to the invention, and these enhancements, improvements, and modifications may nonetheless fall within the spirit and scope of the following claims.

Claims

1. A device for providing propulsion, the device comprising, an array of thrusters, the array of thrusters being an array of field effect electrostatic propulsion thrusters,a fuel container containing propellant for producing thrust from the array of thrusters, the fuel container comprising passive plumbing for communicating the propellant to the array of thrusters, andelectronics for delivering power to the array of thrusters for generating thrusts during ionization and acceleration of the propellant by the array of thrusters, the electronics controlling individually the field effect electrostatic propulsion thrusters of the array of thrusters.

2. The device of claim 1, wherein, the electronics comprises a power converter and a solar cell array for delivering power to the array of thrusters.

3. The device of claim 1 wherein the electronics comprises, a battery for storing electrical power for delivering electrical power to the array of thrusters.

4. The device of claim 1 wherein the electronics comprises, a command decoder for receiving commands to control the array of thrusters, anda data processor for providing data indicating an amount of the propellant available to the array of thrusters.

5. The device of claim 1 wherein, the passive plumbing comprises passive means disposed in the fuel container for drawing the propellant by capillary action from the fuel container to the array of thrusters.

6. The device of claim 1 further comprising, data contacts for routing commands to the device and for routing data from the device, andheat sink contacts for transferring heat from the device to a heat sink.

7. The device of claim 1 further comprising, a data transmitter antenna for transmitting data,a command receiver antenna for receiving commands, anda transceiver for communicating the data to the data transmitter antenna and for receiving the commands from the command receiver.

8. The device of claim 1 further comprising, a heater for maintaining the propellant in a liquid state.

9. The device of claim 1 wherein, the device is a micromachined modular device, andthe device has a modular shape of any solid shape containing at least one planar surface for supporting the array of thrusters.

10. A system for providing thrust on a spacecraft having a surface, the system comprising, a controller for providing commands,devices, the devices being modular propulsion devices disposed in an array on the surface, each of the devices comprises:an array of thrusters, the array of thrusters being an array of field effect electrostatic propulsion thrusters, each of the field effect electrostatic propulsion thrusters are micromachined thrusters;a fuel container containing propellant for producing thrust from the array of thrusters, the fuel container comprising passive plumbing for communicating the propellant to the array of thrusters; andelectronics for delivering power to the array of thrusters for generating thrusts during ionization and acceleration of the propellant by the array of thrusters, the electronics controlling individually the field effect electrostatic propulsion thrusters of the array of thrusters, the electronics for receiving commands from the controller, the devices are disposed in an array about and on the surface of the spacecraft.

11. The system of claim 10 wherein the electronics comprise, a power converter,a solar cell array for delivering power the array of thrusters, and,a battery for storing solar energy from the solar cell array and through the power converter and for delivering power to the array of thrusters.

12. The system of claim 10 wherein the electronics comprises, a command decoder for receiving commands from the controller to control the array of thrusters, anda data processor for providing data indicating a state of the array of thrusters.

13. The system of claim 10 wherein, the passive plumbing comprises a passive means disposed in the fuel container for drawing the propellant by capillary action from the fuel container to the array of thrusters.

14. The system of claim 10 wherein, each of the devices further comprises a contact for routing commands from the controller to the device and for routing data from the device to the controller.

15. The system of claim 10 further comprising, a heat sink receiving waste heat from the devices, each of the devices is coupled to the heat sink for transferring heat from the devices to the heat sink.

16. The system of claim 10 wherein the controller comprises a command and data controller for generating commands to the devices and processing data from the devices,the controller comprises a command and data transceiver for communicating the commands and data, andthe controller comprises a system antenna for communicating commands to the devices and for receiving data from the devices,and wherein, the electronics comprises:a command decoder for receiving the commands from the controller to control the array of thrusters;a data processor for providing data communicated to the controller for indicating a state of the array of thrusters;a data transmitter antenna for transmitting the data;a command receiver antenna for receiving the commands; anda transceiver for communicating the data to the data transmitter antenna and for receiving the commands from the command receiver.

17. The system of claim 10 further wherein, each of the devices comprises a heater for maintaining the propellant in a liquid state.

18. The system of claim 10 wherein, the devices are in a shape selected from the group consisting of cubes, squares, rectangles, hexagons, and triangles comprising at least one planar surface for supporting the array of thrusters, andthe devices are micromachined devices.

19. The system of claim 10 wherein, the controller comprises a system battery for delivering power to the devices.

20. The system of claim 10 wherein, the controller comprises a system antenna for propagating an electromagnetic beam, andthe devices comprise an device antenna for receiving the electromagnetic beam for providing power to the devices.