Spacecraft provided with low and high thrust propulsion systems

Abstract

The spacecraft is equipped with a low-thrust and high-thrust space propulsion system comprising at least one water reservoir (1) containing liquid water, a high-thrust propulsion section and a low-thrust propulsion section. The high-thrust propulsion section has a high-thrust engine comprising a regulating valve (V1) for withdrawing water from the liquid water reservoir (1), a device for decomposing (2) the liquid water into gaseous hydrogen and gaseous oxygen, associated storage tanks (3, 4), a combustion chamber (5) in which the gaseous hydrogen reacts with the gaseous oxygen, and an exhaust nozzle (6) from the combustion chamber (5). The low-thrust propulsion section comprises a liquid water supply line (10) and a plurality of liquid water outlets in the form of a plurality of branches (11-1n), each comprising a regulating valve (21-2n), a vaporization chamber (31-3n) and an expansion nozzle (41-4n).

Description

Technical Field

[0001] This invention relates to a spacecraft equipped with both low-thrust and high-thrust propulsion systems, also known as dual-mode propulsion. The spacecraft is a satellite. Background Technology

[0002] In recent years, investment has been increasing in order to launch new satellites (usually in the form of constellations) to achieve global and real-time connectivity and observation.

[0003] Increased investment has enabled the development of technologies for miniaturizing propulsion systems, allowing for the creation of smaller satellite platforms. Advantages are gained, such as reduced satellite costs while performing the same functions, and shorter timeframes for satellites whose design, manufacturing, and launch are always technologically advanced. In fact, nanosatellites take approximately 2-3 years from design to launch into orbit, while the design and launch of large satellites can take decades.

[0004] Nanosatellites require new propulsion systems that are small enough and powerful enough to perform the required maneuvers.

[0005] Satellites require propulsion systems, which are basically: 1) for attitude and control maneuvers (RCS – Reaction Control System) to control the satellite's attitude and reposition itself; 2) for orbit maneuvers (Delta-V) to enter an operational orbit or deorbit at the end of its service life, either naturally or on demand; and 3) for other maneuvers that can be considered combinations of previous maneuvers.

[0006] These maneuvers require two types of thrust. Attitude and control maneuvers require low thrust, while trajectory changes typically require high thrust.

[0007] Currently, low-thrust maneuvering on small satellites typically uses electric propulsion systems, while high-thrust maneuvering requires the addition of another propulsion system, which introduces complexities such as increased weight, reduced payload volume, increased cost, and reduced reliability.

[0008] If a second propulsion system is not added, a low-thrust propulsion system will be needed to perform maneuvers with high thrust, resulting in a significant increase in the time required to complete maneuvers and a significant reduction in the satellite's lifespan.

[0009] EP 3348671 A1 discloses a space propulsion system in a spacecraft comprising: a reservoir containing liquid water and a drive unit including a regulating valve for drawing liquid water from the reservoir; a water splitting device for splitting liquid water into gaseous hydrogen and gaseous oxygen; a combustion chamber in which gaseous hydrogen and gaseous oxygen react; and an exhaust nozzle from the combustion chamber.

[0010] In addition, EP 3246559 A1 describes a space propulsion system similar to EP 3348671 A1.

[0011] US 2004 / 245406 A1 describes a microthruster comprising a reaction chamber for providing a propulsion plume, which is directed from a nozzle to the outside of a spacecraft to provide thrust. The single-component propellant used may be water.

[0012] The book *Fundamental Ground Experiment of a WaterResistojet Propulsion System: AQUARIUS Installed on a 6UCubeSat: EQUULEUS* (Trans. JSASS Aerospace Tech. Japan, Vol. 16, No. 5, pp. 427-431, 2018) by Jun ASAKAWA et al. describes the thrust generation process of AQUARIUS using water as a propellant. Liquid water is contained in a bladder within a pressurized tank. Water exiting the bladder enters a vaporization chamber equipped with a drain valve and a pressure sensor via a regulating valve. For the first part, the vapor exiting the vaporization chamber is sent to two Delta-V thrusters via corresponding Delta-V thruster valves. Each of these Delta-V thrusters includes a preheater, a Delta-V thruster insulator, and a nozzle. In the second part, the vapor exiting the vaporization chamber is delivered to four RCS thrusters via corresponding RCS thruster valves. Each of the four RCS thrusters includes a preheater, an RCS thruster insulator, and an RCS nozzle. In the same document, it can be seen that the thrust provided by the Delta-V thrusters is 4.0 mN, while the thrust provided by the RCS thrusters is 2.0 mN. AQUARIUS demonstrates the convenience of using a single propellant (i.e., water) to produce both low and high thrust. However, the high thrust produced by the AQUARIUS Delta-V thrusters is very small, resulting in very slow orbital maneuvers and the satellite spending part of its lifespan in an inactive state.

[0013] The same applicant filed international patent application WO 2019 / 021234, which describes a space propulsion system comprising: a liquid water reservoir; an electrolysis device for splitting water into oxygen and hydrogen; a combustion chamber into which hydrogen and oxygen are injected for combustion; and a supersonic nozzle for discharging the combustion products. Such a propulsion system provides thrust orders of magnitude higher than that obtained by the AQUARIUS Delta-V thruster while maintaining the same size. Summary of the Invention

[0014] The object of the present invention is to provide a single propulsion system that is versatile enough to perform both low-thrust and high-thrust maneuvers.

[0015] Another object of the present invention is to create a propulsion system that is compact enough to be installed on a nanosatellite.

[0016] Another objective is to provide a propulsion system that uses a single propellant as at least its primary energy source.

[0017] Finally, another objective is to provide a low-thrust and high-thrust propulsion system that is particularly efficient in terms of high thrust and can conveniently use water (directly or indirectly) as the sole propellant.

[0018] According to the present invention, the propulsion system is designed to use only liquid water to feed both the high-thrust and low-thrust units. The high-thrust unit utilizes water electrolysis and the combustion of hydrogen and oxygen. Alternatively, additional hydrogen / oxygen generation systems (such as microwave systems) may also be used. The low-thrust unit utilizes the expansion of water vapor obtained by heating the water itself.

[0019] Two pipelines originate from the liquid water reservoir, one for high thrust and one for low thrust.

[0020] High-thrust pipeline setup:

[0021] - Electrolyzers or other systems, such as microwave systems, use electricity obtained from solar panels or even potentially from batteries or other sources to break the hydrogen-oxygen bonds in water, thereby producing gaseous hydrogen and gaseous oxygen.

[0022] - The gas may or may not be accumulated in external or internal storage tanks of the electrolyzer or other hydrogen and oxygen generation systems;

[0023] - The gas is introduced into the thrust chamber, whether or not it is premixed, so that combustion of the gas is triggered by a catalytic material and / or spark and / or resistance by means of heating and / or a combination of these means;

[0024] The hot gases from combustion expand in the exhaust nozzle to obtain the required thrust;

[0025] - There are valves and sensors required for the system to function correctly.

[0026] Low-thrust pipeline setup:

[0027] - Water enters the thrust chamber and is heated to a steam state by resistance;

[0028] - To expand the steam in the relevant exhaust nozzle to obtain the low thrust required for the desired maneuvering;

[0029] - There are valves and sensors required for the system to function correctly. Attached Figure Description

[0030] The object and features of the present invention will become clearest from the description of spacecraft equipped with low-thrust and high-thrust propulsion systems, with reference to the accompanying drawings, in which:

[0031] Figure 1

[0032] [ Figure 1 [A] is an illustrative block diagram of a propulsion system according to the present invention; and

[0033] Figure 2

[0034] [ Figure 2 It is equipped with [ Figure 1 A schematic 3D cutaway view of the satellite's propulsion system. Detailed Implementation

[0035] refer to[ Figure 1 The propulsion system according to the present invention includes a high-thrust propulsion section and a low-thrust propulsion section.

[0036] The high-thrust propulsion section includes a thruster comprising: a water reservoir 1 for containing liquid water; a water splitting device 2 for splitting the liquid water into gaseous hydrogen and gaseous oxygen and storing them respectively in a gaseous hydrogen storage tank 3 and a gaseous oxygen storage tank 4; and a high-thrust chamber 5 having a nozzle 6 for discharging combustion products. The splitting device can be a water electrolyzer that electrolyzes water into gaseous hydrogen and gaseous oxygen, or a microwave water splitting device for splitting water into gaseous hydrogen or gaseous oxygen, or another device. As for the hydrogen storage tank 3 and the oxygen storage tank 4, they can be simplified to a single unit in which hydrogen and oxygen are mixed and supplied to the combustion chamber while already mixed.

[0037] Alternatively, the accumulation of gaseous hydrogen and gaseous oxygen (whether or not premixed) occurs within the water splitting unit 2.

[0038] Another configuration could be one without any storage tanks: this solution assumes that the instantaneous and / or continuous decomposition of water by means of an electrolyzer or microwave device or different devices produces enough hydrogen and oxygen to enable the timely and / or continuous thrust required to carry out the mission, and that there is no need for the generated gases to accumulate inside or outside the water decomposition device before entering the combustion chamber.

[0039] The low-thrust propulsion section of the propulsion system includes a liquid water supply line 10 from a reservoir 1 and multiple water derivatives in the form of branches 11-1n, where n indicates the total number of branches. Each branch 11-1n has a regulating valve 21-2n, a vaporization chamber 31-3n, and an expansion nozzle 41-4n downstream of the vaporization chamber 31-3n.

[0040] Despite in [ Figure 1 The block diagram shows six vaporization chambers and seven flow control valves; however, it is preferred that the low-thrust propulsion section has at least four vaporization chambers.

[0041] The presence of at least one electronic board is required to control the operation of the space propulsion system and interact with other satellite systems, such as onboard computers with mission specifications.

[0042] Basically, those chambers designated as high-thrust chambers are those capable of providing thrust on the order of approximately 0.1 N and greater. The thruster according to the invention can also provide thrust up to 10 N or greater.

[0043] The vaporization chamber of the low-thrust propulsion section according to the invention is characterized by a thrust on the order of approximately 0.001 N or less; the thrust is essentially in the range of 1-10 mN.

[0044] High-thrust chambers can operate under high pressure conditions, even at pressures on the order of approximately 5000 kPa.

[0045] The low-thrust chamber operates under low pressure, even at pressures on the order of less than 100 kPa.

[0046] High-thrust chambers can be in the size of one centimeter (excluding the nozzle). A 10x10 mm (diameter x height) chamber can deliver 1-5 N of thrust.

[0047] Low-thrust chambers can be millimeter-sized, including the nozzle. An 8x8x2 mm (length x width x height) chamber can provide thrust in the range of 1-25 mN.

[0048] High-thrust chambers are made of metallic materials such as steel, titanium, and tungsten. Low-thrust chambers can also be made on a silicon wafer.

[0049] The overall dimensions of low-thrust and high-thrust space propulsion systems, excluding water reservoirs, can be envisioned to be approximately 100x100x40-45mm (length x width x height) and weigh approximately 400g.

[0050] The advantages of the present invention are understood. Although in different physical and chemical forms, the propellant is unique: liquid water. It is used on the same spacecraft to obtain: 1) high thrust, which is obtained by the splitting of water into gaseous hydrogen and gaseous oxygen, the combustion of hydrogen and oxygen, and the discharge of combustion products through exhaust nozzle 6; and 2) low thrust, which is achieved by vaporizing the water and expanding it in expansion nozzles 41-4n.

[0051] [ Figure 2 ] is equipped with [ Figure 1 A partially cutaway perspective view of a satellite's propulsion system. The satellite has a generally prismatic body 20 with solar panels 21 and 22. The solar panels 21 are partially cut to show a pair of low-thrust nozzles, which are orthogonally positioned at two vertices on one face of the prismatic body 20 and at two consecutive vertices on the opposite face of the prismatic body 20. An exhaust nozzle 6 is schematically shown in a position orthogonal to one face of the prismatic body 20 of the satellite.

[0052] In summary, and to put it simply, the selection of water as the optimal propellant for high- and low-thrust systems is based on several considerations. In general, liquid water is...

[0053] - Economic;

[0054] -Non-toxic;

[0055] -Non-corrosive;

[0056] - It can be easily stored and managed, which further simplifies the process and reduces usage costs;

[0057] - Characterized by high density, which allows for compact systems;

[0058] - Hydrogen / oxygen carrier, which is a chemical couple with the highest performance (high thrust and high specific impulse);

[0059] - The hydrogen / oxygen carrier is not brought into a cryogenic state, and therefore does not involve significant design, economic and management complexities;

[0060] - Universal and modular.

Claims

1. A spacecraft equipped with low-thrust and high-thrust propulsion systems, comprising at least one water reservoir (1) containing liquid water, a high-thrust propulsion section, and a low-thrust propulsion section, characterized in that: The high-thrust propulsion section includes at least one high-thrust generator, which includes a regulating valve (V1) for drawing liquid water from the at least one water reservoir (1), a water decomposition device (2) for decomposing the liquid water into gaseous hydrogen and gaseous oxygen, a combustion chamber (5) in which gaseous hydrogen reacts with gaseous oxygen, and an exhaust nozzle (6) from the combustion chamber (5). The low-thrust propulsion section includes a liquid water supply line (10) and multiple liquid water outlets in the form of multiple branches (11-1n), each of the multiple branches including a regulating valve (21-2n), a vaporization chamber (31-3n) and an expansion nozzle (41-4n) located downstream of the vaporization chamber (31-3n).

2. The spacecraft according to claim 1, wherein, The high-thrust generator includes an electrolyzer suitable for splitting liquid water into gaseous hydrogen and gaseous oxygen.

3. The spacecraft according to claim 1, wherein, The high-thrust generator includes a microwave device suitable for splitting liquid water into gaseous hydrogen and gaseous oxygen.

4. The spacecraft according to claim 1, wherein, At least one gaseous hydrogen storage tank (3) and at least one gaseous oxygen storage tank (4) are provided between the water splitting device (2) and the combustion chamber (5).

5. The spacecraft according to claim 1, wherein, At least one storage tank for premixing hydrogen and oxygen gas is provided between the water splitting device (2) and the combustion chamber (5).

6. The spacecraft according to any one of claims 2 and 3, wherein, A gaseous hydrogen storage tank and a gaseous oxygen storage tank are provided in the water splitting device (2).

7. The spacecraft according to claim 1, wherein, No gaseous hydrogen storage tanks or gaseous oxygen storage tanks were installed.

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