Spacecraft Propellant Management via Tank Segmentation and Condensation
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Solution Overview
Problem
In spacecraft propulsion systems, cold gas thrusters become ineffective at pressures below 25-35 bar, leading to contingency situations where attitude control is lost due to the unavailability of high-pressure inert gas for contingency use.
Innovation Solution
A propulsion system with a pneumatic arrangement of commandable valves that isolates a reserve pressurant tank at high pressure, allowing it to maintain high pressure until near the end of the mission, and a condenser that scavenges inert gas from partially depleted tanks by cooling to condensation temperature, ensuring gas availability for cold gas thrusters.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Duration of action of moving object
If all pressurant tanks are pneumatically coupled to electric thrusters from the beginning of the mission, then electric thrusters can operate throughout the mission, but cold gas thrusters become ineffective when pressure drops below 25-35 bar
Solution Approach 1:
The pressurant tank system is segmented into two distinct subsets: a first subset of pressurant tanks coupled to cold gas thrusters and a second subset of pressurant tanks coupled to electric thrusters. This segmentation allows independent management of high-pressure reserves for contingency cold gas operations versus continuous low-pressure supply for electric thruster operations.
Solution Approach 2:
The first subset of pressurant tanks is pre-filled and maintained at high pressure (above 25-35 bar) throughout the mission as a reserve. This preliminary preparation ensures that cold gas thrusters remain available for contingency attitude control operations throughout the entire mission duration, even as the second subset depletes.
2Device complexity
If a single pressurant tank system is used for both cold gas and electric thrusters, then system complexity is reduced, but high-pressure gas becomes unavailable for contingency cold gas operations
Solution Approach 1:
The pneumatic arrangement incorporates commandable valves that dynamically reconfigure the coupling between pressurant tank subsets and thruster subsets based on mission phase and operational requirements. This dynamic control enables the system to adapt between different operational modes while maintaining manageable complexity through automated valve management.
Solution Approach 2:
The pressurant tank system is designed with multi-functionality: the first subset of tanks serves cold gas thrusters for contingency attitude control, while the second subset serves electric thrusters for normal operations. Both subsets can be independently managed and reconfigured to serve different functions as mission requirements change.
3Quantity of substance
If pressurant tanks are depleted during the mission, then propellant mass decreases, but cold gas thruster effectiveness is lost
Solution Approach 1:
The pressurant tank system is segmented into two distinct subsets: a first subset of pressurant tanks coupled to cold gas thrusters and a second subset of pressurant tanks coupled to electric thrusters. This segmentation allows independent management of high-pressure reserves for contingency cold gas operations versus continuous low-pressure supply for electric thruster operations.
Solution Approach 2:
The first subset of pressurant tanks is pre-filled and maintained at high pressure (above 25-35 bar) throughout the mission as a reserve. This preliminary preparation ensures that cold gas thrusters remain available for contingency attitude control operations throughout the entire mission duration, even as the second subset depletes.
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
Maintains high-pressure inert gas availability for cold gas thrusters throughout most of the mission life, ensuring effective thrust control and extending the operational life of the spacecraft.
Implementation Method 1
a condenser configured to scavenge a quantity of the inert gas from the pressurant tanks by cooling to a condensation temperature
Implementation Method 2
a pneumatic arrangement including commandable valves, the pneumatic arrangement configured such that a first subset of the pressurant tanks is isolatable, by the commandable valves, from a second subset of the pressurant tanks
Implementation Method 3
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, argon and krypton and accelerate the resulting ions
Implementation Method 4
cold gas thrusters operable to accelerate the inert gas normally provided to the electric thrusters
Data Source
AI summary
A spacecraft includes a propulsion system including an inert gas stored in a set of pressurant tanks, one or more electric thrusters operable with the inert gas, one or more cold gas thrusters operable with the inert gas; and a pneumatic arrangement including commandable valves.