Satellite Fill/Drain Valve Access for Robotic Propellant Resupply
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Solution Overview
Problem
Existing satellites are not designed for robotic propellant resupply, posing challenges in accessing fill/drain valves due to protective thermal blankets, lockwires, and valve caps, and risking dangerous fuel mixing during transfer.
Innovation Solution
A refueling tool system mounted on a servicing spacecraft, equipped with a differential gearbox, cam wrench mechanisms, and a fuel oxidizer exchanger, enables remote opening and closing of satellite valves, ensuring safe transfer of propellants through separate pathways for fuel and oxidizer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If satellites are designed with protective thermal blankets, lockwires, and valve caps on fill/drain valves, then thermal protection and valve security are improved, but accessibility for robotic servicing deteriorates
Solution Approach 1:
The valve access mechanism is divided into multiple removable components: thermal blankets can be peeled back in sections, lockwires can be individually cut and removed, and valve caps can be unscrewed. This segmentation allows robotic tools to systematically remove each protective layer without requiring complete disassembly of the entire valve assembly, thereby improving accessibility while maintaining protection during normal operation.
Solution Approach 2:
The system includes pre-positioned tool interfaces and access mechanisms that are prepared in advance for robotic servicing. The valve caps and protective coverings are designed with predetermined removal mechanisms that can be engaged by robotic tools, allowing the protective layers to be removed before the actual refueling operation begins, thus facilitating easier robotic access.
2Reliability
If fill/drain valves are designed for single-use prior to launch, then simplicity and reliability of original design are improved, but adaptability for robotic propellant resupply deteriorates
Solution Approach 1:
The refueling tool system is designed with universal interfaces that can accommodate different valve types and configurations on various satellites. The tool includes adjustable clamps, multiple coupling mechanisms, and interchangeable end effectors that can adapt to different valve sizes and access requirements, enabling the same tool system to service multiple satellite platforms with different original valve designs.
Solution Approach 2:
The valve access and refueling system incorporates dynamic adjustment capabilities, allowing the robotic tool to adapt its positioning, gripping force, and coupling parameters in real-time based on the specific valve configuration being serviced. This dynamic adaptability enables the system to handle the variability in valve designs across different satellite platforms while maintaining reliable connections.
3Device complexity
If propellant transfer is performed without separate pathways for fuel and oxidizer, then system simplicity is improved, but safety against accidental mixing and explosion deteriorates
Solution Approach 1:
The propellant transfer system is segmented into completely separate pathways: one dedicated pathway for fuel transfer and another dedicated pathway for oxidizer transfer. Each pathway includes its own coupling mechanisms, flow control valves, and monitoring systems. This segmentation physically isolates the fuel and oxidizer streams, eliminating the risk of accidental mixing while maintaining relatively simple individual pathways for each propellant type.
Solution Approach 2:
The system introduces intermediary control mechanisms including automated flow control valves, pressure regulation devices, and real-time monitoring sensors that act as mediators between the fuel and oxidizer pathways. These intermediaries ensure that even if the separate pathways were to converge or if cross-contamination occurred, the mediators would detect and prevent dangerous mixing conditions, thereby maintaining safety without requiring overly complex system architecture.
Data Source
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AI summary
Herein is disclosed a tool, system and method for refueling on-orbit spacecraft. The tool and system are configured to allow for resupply of spacecraft configured to be propelled by either a bipropellant (oxidizer and fuel) or a monopropellant (typically hydrazine). The refueling tool is particularly suited for resupply of satellites not originally prepared for refueling but the system may also be used for satellites specifically designed for refueling.