Unified Spacecraft Propellant Management System
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Solution Overview
Problem
Spacecraft propulsion systems require multiple high-pressure tanks for both chemical and electric thrusters, leading to increased mass and cost due to the need for dedicated pressurant tanks for liquid propellants.
Innovation Solution
A unified propellant management system that uses high-pressure inert gas tanks to pressurize liquid propellant tanks during chemical thruster operation and subsequently utilize the same inert gas for electric thrusters, reducing the number of high-pressure tanks needed by pneumatically coupling the tanks with pressure regulators and commandable valves to manage pressure and gas flow between phases.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If separate high-pressure tanks are used for chemical and electric thrusters, then each thruster type has dedicated propellant supply, but the number of tanks and structural hardware increases mass and cost
Solution Approach 1:
The patent merges the propellant supply systems for chemical and electric thrusters by using a single high-pressure tank containing both liquid propellant and inert gas. The liquid propellant is dispensed to chemical thrusters while the inert gas is dispensed to electric thrusters, eliminating the need for separate high-pressure tanks and reducing overall system mass.
Solution Approach 2:
The single high-pressure tank serves multiple functions: storing liquid propellant for chemical thrusters, storing inert gas for pressurizing the liquid propellant, and storing inert gas for electric thrusters. This multi-functional design reduces the number of components and structural hardware required.
2Quantity of substance
If multiple high-pressure tanks are used to store both liquid propellant and inert gas, then propellant availability is ensured, but the number of tanks increases system complexity
Solution Approach 1:
The patent combines multiple propellant storage functions into a single high-pressure tank. The tank contains both liquid propellant and inert gas, with a dispenser system that can selectively deliver either substance to the appropriate thruster type, thereby reducing system complexity while maintaining propellant availability.
Solution Approach 2:
The dispenser system acts as an intermediary between the single high-pressure tank and the two types of thrusters. It manages the complex task of distinguishing between liquid propellant and inert gas, and directing them to the correct thruster, thereby simplifying the overall system architecture.
3Reliability
If dedicated pressurant tanks are used for liquid propellants, then propellant delivery is reliable, but the number of high-pressure tanks increases
Solution Approach 1:
The patent merges the pressurant storage function with the liquid propellant storage function by containing both substances in a single high-pressure tank. The inert gas serves dual purposes: pressurizing the liquid propellant for reliable delivery to chemical thrusters and serving as propellant for electric thrusters.
Solution Approach 2:
The inert gas in the high-pressure tank performs multiple functions: it acts as pressurant for the liquid propellant system and as propellant for the electric thruster system. This multi-functionality eliminates the need for separate pressurant tanks.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach reduces the mass and cost associated with tankage and structural hardware by sharing inert gas for both thruster types, optimizing propellant usage across mission phases and enhancing propulsion efficiency.
Implementation Method 1
pneumatically coupled with the one or more pressurant tanks by way of a first pressure regulator having a low pressure output
Implementation Method 2
the ullage volume is pneumatically coupled with at least one of the pressurant tanks by way of a second pressure regulator having an output set to the intermediate pressure
Implementation Method 3
The one or more electric thrusters may be pneumatically coupled with the one or more pressurant tanks by way of a first commandable valve and the first pressure regulator
Implementation Method 4
Electric thrusters may operate at an Isp of 1000-4000 seconds, by using spacecraft power to ionize high atomic number inert gases such as xenon or krypton and accelerate the resulting ions
Implementation Method 5
Chemical thrusters suitable for spacecraft propulsion systems accelerate combustion or decomposition products of liquid propellants such as hydrazine and nitrogen tetroxide
Data Source
AI summary
A spacecraft includes a propulsion system that includes one or more pressurant tanks configured to store an inert gas at a high pressure, one or more propellant tanks configured to store liquid propellant at an intermediate pressure, electric thrusters operable with the inert gas at a low pressure and pneumatically coupled with the one or more pressurant tanks by way of a first pressure regulator, and chemical thrusters operable with the liquid propellant. The inert gas is one or a mixture of two or more of xenon, argon and krypton. At least a portion of the liquid propellant is stored in at least one of the propellant tanks, the propellant tank including an ullage volume pneumatically coupled with at least one of the pressurant tanks by way of a second pressure regulator having an output set to the intermediate pressure and the ullage volume is pressurized by the inert gas.