SPACECRAFT PROVIDED WITH LOW AND HIGH THRUST PROPULSION SYSTEM

Abstract

A spacecraft is equipped with a low and high thrust space propulsion system including at least one water reservoir (1) containing liquid water, a high thrust propulsion part and a low thrust propulsion part. The high thrust propulsion part has a high thruster including a regulation valve (V1) for drawing water from the liquid water reservoir (1), a device for splitting (2) liquid water into gaseous hydrogen and gaseous oxygen, relative 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 part comprises a liquid water supply line (10) and a plurality of liquid water outlets in a plurality of branches (11-1n) individually including a regulating valve (21-2n), a vaporization chamber (31-3n) and an expansion nozzle (41-4n).

Claims

1. A spacecraft provided with a low and high thrust propulsion system, including at least one water reservoir (1) containing liquid water, a high thrust propulsion part and a low thrust propulsion part, characterized in that: the high thrust propulsion part comprises at least one high thruster including a regulating valve (V1) for sucking liquid water from the at least one water reservoir (1), a water splitting device (2) for splitting the liquid water into gaseous hydrogen and gaseous oxygen, a combustion chamber (5) in which the gaseous hydrogen reacts with the gaseous oxygen and an exhaust nozzle (6) from the combustion chamber (5), and the low thrust propulsion part comprises a liquid water supply line (10) and a plurality of liquid water outlets in a plurality of branches (11-1n) individually including a regulating valve (21-2n), a vaporization chamber (31-3n) and an expansion nozzle (41-4n) downstream of the vaporization chamber (31-3n).

2. The spacecraft according to claim 1, wherein the high thruster comprises an electrolyser adapted to split the liquid water into gaseous hydrogen and gaseous oxygen.

3. The spacecraft according to claim 1, wherein the high thruster comprises a microwave device adapted to split the 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 premixed hydrogen and oxygen gaseous is provided between the water splitting device (2) and the combustion chamber (5).

6. The spacecraft according to claim 2, wherein the gaseous hydrogen storage tank and the gaseous oxygen storage tank are inside the water splitting device (2).

7. The spacecraft according to claim 1, wherein no gaseous hydrogen storage tank and no gaseous oxygen storage tank are provided.

8. The spacecraft according to claim 3, wherein the gaseous hydrogen storage tank and the gaseous oxygen storage tank are inside the water splitting device (2).

Description

BRIEF DESCRIPTION OF DRAWINGS

[0030] The objects and features of the present invention will become most clear from the description of a spacecraft provided with a low and high thrust propulsion system, with reference to the attached figures in which:

[0031] FIG. 1 is an illustrative block diagram of the propulsion system according to the present invention; and

[0032] FIG. 2 is a partially cut-away schematic perspective view of a satellite equipped with the propulsion system in [FIG. 1].

DESCRIPTION OF AN EMBODIMENT

[0033] Referring to [FIG. 1], the propulsion system according to the present invention comprises a high thrust propulsion part and a low thrust propulsion part.

[0034] The high thrust propulsion part has 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 in a gaseous hydrogen storage tank 3 and in a gaseous oxygen storage tank 4, respectively, and a high thrust chamber 5 with nozzle 6 for discharging the combustion products. The splitting device could be a water electrolyser that electrolyses water into gaseous hydrogen and gaseous oxygen, or a water microwave splitting device for splitting water into gaseous hydrogen and gaseous oxygen, or another device. As for the hydrogen storage tank 3 and the oxygen storage tank 4, they could be reduced to a single one in which hydrogen and oxygen are mixed and fed into the combustion chamber already mixed.

[0035] Alternatively, the accumulation of gaseous hydrogen and gaseous oxygen, premixed or not, is inside the water splitting device 2.

[0036] Another configuration could be that without any storage tank: this solution assumes that the splitting of water, instantaneous and/or continuous, by means of an electrolyser or microwave device, or different device, produces enough hydrogen and oxygen to be able to perform punctual and/or continuous thrusts, as needed by a mission, and to not require accumulation of the gases produced, either internally or externally to the water splitting device, before entering the combustion chamber.

[0037] The low thrust propulsion part of the propulsion system includes a supply line 10 of liquid water from reservoir 1 and a plurality of water derivations in branches 11-1n, where n indicates the total number of branches. Each branch 11-1n has a regulation valve 21-2n, a vaporization chamber 31-3n and an expansion nozzle 41-4n downstream of the vaporization chamber 31-3n.

[0038] It is preferable that the low thrust propulsion part has at least four vaporization chambers, although six vaporization chambers with seven flow control valves are shown in the block diagram of [FIG. 1].

[0039] The presence of at least one electronic board is required to control the operation of the space propulsion system and interaction with the other satellite systems, such as an on-board computer with mission specifications.

[0040] Usually, indicated as high thrust chambers are those able to provide thrusts of about 0.1 N, as order of magnitude, and more. The thruster according to the invention is able to provide thrusts also up to 10 N or more.

[0041] The vaporization chambers of the low thrust propulsion part according to the invention are characterized by thrusts about 0.001 N, as order of magnitude, or less; usually there are thrusts in the range of 1-10 mN.

[0042] The high thrust chamber can work at high pressures, even, as order of magnitude, about 5,000 kPa.

[0043] Low thrust chambers work at low pressures, even, as order of magnitude, below 100 kPa.

[0044] The high thrust chamber can have dimensions of the order of one centimeter (nozzle excluded). A chamber of 1010 mm (diameterheight) can give a thrust of 1-5 N.

[0045] The low thrust chambers can have dimensions of the order of millimeters, nozzle included. Chambers of 882 mm (lengthwidthheight) can provide thrusts in the range of 1-25 mN.

[0046] The high thrust chamber is made of metal materials, such as steel, titanium, tungsten. The low thrust chambers can also be on silicon wafers.

[0047] A global dimension of the low and high thrust space propulsion system, excluding the water reservoir, can be envisaged, with dimensions around 10010040-45 mm (lengthwidthheight) and a weight of around 400 g.

[0048] 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 through water splitting into gaseous hydrogen and gaseous oxygen, hydrogen and oxygen combustion and discharge of combustion products through an exhaust nozzle 6; and 2) low thrust by vaporizing water and making it expand in the expansion nozzle 41-4n.

[0049] FIG. 2 is a partially cut-away schematic perspective view of a satellite equipped with the propulsion system of [FIG. 1]. The satellite has a substantially prismatic body 20 with solar panels 21, 22. The solar panel 21 is partially cut to show a pair of low thrust nozzles placed mutually orthogonal on two vertices of one face of the prismatic body and on two consecutive vertices of the opposite face of the prismatic body 20. The discharge nozzle 6 is shown schematically in a position orthogonal to one face of prismatic body 20 of the satellite.

[0050] In conclusion and to summarize, the choice of using water as an optimal propellant for a low-high thrust system is based on several considerations. In summary, liquid water is [0051] economic; [0052] non-toxic; [0053] not corrosive; [0054] easily storable and manageable, which further simplifies the processes and the cost of use; [0055] characterized by a high density, and this allows compact systems; [0056] hydrogen/oxygen carrier, which are the chemical couple with the highest performance (high thrust and high specific impulse); [0057] hydrogen/oxygen carrier without being brought to the cryogenic state, and therefore does not involve significant design, economic and management complications; [0058] versatile and modular.