Tether-Based Reaction Control for Atmospheric Entry
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Solution Overview
Problem
Conventional reaction control systems (RCS) for spacecraft are limited by fuel capacity, are costly, complex, and unreliable, and they impose significant physical and thermal stresses on spacecraft during atmospheric entry.
Innovation Solution
The use of tether-based RCS systems, which generate moments about the center of mass by producing friction forces on tethers attached to the spacecraft, allowing for attitude control and reducing thermal and physical stresses during atmospheric entry.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional reaction control systems are used for spacecraft attitude control, then attitude control capability is provided, but fuel capacity limitations, cost, complexity, and reliability issues arise
Solution Approach 1:
The patent extracts the reaction control function from the conventional fuel-based RCS system and transfers it to the tether system. The tether, when deployed during atmospheric entry, generates aerodynamic forces that provide attitude control without requiring onboard fuel, thereby simplifying the system and improving reliability.
Solution Approach 2:
The patent introduces the atmosphere as an intermediary medium to enable attitude control. Instead of using onboard propellants, the system utilizes atmospheric aerodynamic forces acting on the tether to generate the necessary moments for attitude control, eliminating fuel consumption and associated reliability issues.
2Ease of operation
If conventional reaction control systems are used during atmospheric entry, then attitude control is achieved, but significant physical and thermal stresses are imposed on the spacecraft
Solution Approach 1:
The patent converts the harmful aerodynamic heating and drag forces, which are inevitable during atmospheric entry, into a beneficial mechanism for attitude control. By deploying the tether to interact with the atmospheric flow, the system generates aerodynamic moments that control attitude while simultaneously managing the thermal and physical stresses through controlled drag.
3Object-affected harmful factors
If tether-based RCS systems are used, then thermal and physical stresses are reduced, but system complexity increases due to tether deployment mechanisms
Solution Approach 1:
The patent employs a dynamic tether deployment mechanism that can adjust the tether length and configuration during flight. This dynamic capability allows the system to optimize performance while managing complexity, as the tether can be deployed only when needed during atmospheric entry and retracted or adjusted during other phases of flight.
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
The tether-based RCS systems enable efficient attitude control and reduce the thermal and acceleration loads on spacecraft during atmospheric entry, thereby improving the safety and reliability of the reentry process.
Implementation Method 1
generate moments about the center of mass by producing friction forces on tethers attached to the spacecraft
Implementation Method 2
reduce the thermal and acceleration loads on spacecraft during atmospheric entry
Data Source
AI summary
Tether-based reaction control systems for spacecraft undergoing atmospheric entry or reducing orbital energy, including systems that use atmospheric drag on one or more tethers to alter the angle of attack of the spacecraft during its atmospheric transit to reduce the thermal and mechanical loads on the spacecraft during the reentry process. Systems may include tethers that together generate a force that functionally acts on the spacecraft at a point that is offset from the spacecraft's center of mass. Such systems may be either actively or passively controlled.