Thruster Realignment Mechanism for Spacecraft Propulsion
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Solution Overview
Problem
Electrically powered spacecraft propulsion systems face challenges in maintaining the thrust vector aligned with the spacecraft's center of gravity due to initial misalignment, external influences, thruster failure, and propellant depletion, leading to spurious torques that are difficult and costly to compensate.
Innovation Solution
A thruster realignment mechanism that adjusts the individual thrust vectors of electric thrusters to align with either the initial or final center of gravity, minimizing torque and cosine losses, using a bi-stable or reversible mechanism to realign thrusters in response to failures or time criteria, potentially incorporating non-explosive actuators and pivotable plates.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If standard chemical propulsion systems use additional thrusters to compensate for thrust vector offset, then the offset problem is resolved, but the system becomes more complex and costly
Solution Approach 1:
The patent applies dynamics by making the thruster assembly movable relative to the spacecraft body through a realignment mechanism. This allows the thrust vector to be dynamically adjusted to pass through the center of gravity, eliminating the need for multiple compensating thrusters and reducing system complexity while maintaining reliable thrust alignment
2Reliability
If electric propulsion systems use multiple thrusters to compensate for thrust vector offset, then alignment is improved, but the cost per thruster increases significantly
Solution Approach 1:
The realignment mechanism allows a single electric thruster to dynamically adjust its orientation to maintain proper alignment with the center of gravity. This eliminates the need for multiple expensive electric thrusters, significantly reducing system cost while maintaining reliable thrust vector alignment through mechanical adjustment
3Manufacturing precision
If thruster pointing mechanisms are used to align thrust vectors, then alignment precision is improved, but the mechanism becomes heavy and occupies significant space
Solution Approach 1:
The patent segments the realignment function from complex pointing mechanisms to a simpler mechanism that only needs to adjust the thruster assembly orientation. This segmented approach achieves sufficient alignment precision for electric propulsion while minimizing weight and space requirements by focusing only on the essential realignment function
4Reliability
If internal balance mass is used to adjust center of gravity, then alignment is improved, but only very minor shifts can be achieved
Solution Approach 1:
Instead of using limited-range balance mass, the patent employs a dynamic realignment mechanism that can adjust the thruster orientation through a practical range of motion. This provides sufficient adaptability to compensate for center of gravity shifts during propellant depletion while achieving the necessary alignment reliability
Data Source
AI summary
An electrically powered propulsion system for a spacecraft includes a first center of gravity at a first time of operation and a second center of gravity at a second time of operation, where the second center of gravity is different from the first center of gravity. The electrically powered propulsion system includes a thruster realignment mechanism and at least two thrusters coupled to the thruster realignment mechanism. Each of the at least two thrusters has an individual thrust vector. The thruster realignment mechanism is adapted such that, in a first position, the individual thrust vectors of the at least two thrusters pass through the first center of gravity and that, in a second position, the individual thrust vectors of the at least two thrusters pass through the second center of gravity. The thruster realignment mechanism holds the first position in the event all of the at least two thrusters are without any failure. In addition, the thruster realignment mechanism realigns the thrusters to the second position in the event of at least one of (i) a failure of one of the at least two thrusters, and (ii) a predetermined time criterion is fulfilled.