Propellant Transfer System for On-Orbit Satellite Refueling
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Solution Overview
Problem
Current technologies lack the capability to effectively resupply propellant to satellites not originally designed for refueling, posing challenges in accessing and transferring propellants due to their design and safety concerns, such as accidental mixing of fuels and oxidizers, which limits the extension of satellite operational life and recovery of asset value.
Innovation Solution
A propellant transfer system mounted on a servicer spacecraft that can dynamically regulate flow rates and pressures to transfer bipropellants, monopropellants, and pressurants, using a backup fill/drain valve to ensure safe and flexible propellant delivery, including direct and cycled transfer methods, and a computer control system for precise operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Duration of action of moving object
If propellant transfer system is applied to satellites not designed for refueling, then operational life of satellite is extended, but device complexity and difficulty of operation increase due to need to access and manipulate sealed propellant valves
Solution Approach 1:
The propellant transfer system is divided into separate functional modules: a robotic manipulator for physical access, a valve actuation mechanism for opening sealed valves, and a propellant transfer apparatus for the actual transfer. This segmentation allows each module to be optimized independently and simplifies the overall system architecture.
Solution Approach 2:
A backup fill/drain valve is introduced as an intermediary component that can be accessed and opened by the robotic manipulator. This intermediary valve provides a controlled interface between the external transfer system and the satellite's internal propellant system, enabling safe propellant transfer without directly modifying the original sealed valves.
2Quantity of substance
If robotic manipulation of propellant valves is performed, then propellant resupply is achieved, but reliability decreases due to multiple difficult operations required including cutting thermal blankets, removing lockwires, and mating propellant lines
Solution Approach 1:
The system performs preliminary actions by first using the robotic manipulator to precisely position and open the backup fill/drain valve before initiating propellant transfer. This preliminary valve actuation establishes a controlled pathway and ensures proper connection before the actual propellant flow begins, reducing the risk of failures during the transfer operation.
Solution Approach 2:
The system incorporates feedback mechanisms to monitor the status of valve actuation, connection integrity, and propellant flow rates. This real-time feedback allows the control system to detect and respond to anomalies, ensuring reliable operation and enabling corrective actions if issues arise during the propellant transfer process.
3Ease of manufacture
If propellant transfer is performed without physical modification of client satellite, then asset value is recovered, but ease of manufacture decreases due to need for sophisticated access and transfer mechanisms
Solution Approach 1:
The propellant transfer system is designed with universal components that can interface with multiple types of satellite propellant systems. The robotic manipulator, valve actuation mechanism, and transfer apparatus are configured to work with various satellite designs without requiring custom modifications to each client satellite, thereby improving ease of manufacture and deployment.
Solution Approach 2:
The system utilizes the satellite's existing backup fill/drain valve infrastructure, which was originally designed for ground-based operations. By leveraging this pre-existing component, the system avoids the need to install entirely new valve systems on the satellite, reducing manufacturing complexity while still achieving the goal of propellant transfer without physical modification to the main satellite structure.
4Object-affected harmful factors
If flow rates and pressures are dynamically regulated, then safety is improved by preventing accidental mixing of fuels and oxidizers, but device complexity increases due to need for precise control systems
Solution Approach 1:
The flow regulation system incorporates sensors and control mechanisms that continuously monitor propellant flow rates and pressures. This feedback enables the system to dynamically adjust valve positions and flow characteristics, ensuring that fuels and oxidizers are transferred separately at controlled rates, thereby preventing accidental mixing while maintaining safe operation.
Solution Approach 2:
The propellant transfer system is segmented into separate transfer lines and control mechanisms for different propellant types (fuel and oxidizer). This physical and functional segmentation, combined with independent flow regulation for each line, eliminates the risk of mixing while keeping the control system manageable through modular design.
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
Enables the safe and efficient resupply of propellants to satellites, extending their operational life, reducing the need for satellite replacement, and recovering asset value by allowing propellant transfer without physically modifying the client satellite, while ensuring safety through leak detection and regulated flow rates.
Implementation Method 1
A propellant transfer system is disclosed which uses a pressurized gas in a storage tank to push fluid propellant through a routing tube system
Data Source
Figure 1
Figure 1a
Figure 1b
AI summary
Herein is disclosed a propellant transfer system and method for refueling on-orbit spacecraft. The system and method are configured to allow for resupply of spacecraft configured to be fueled by either a bipropellant (oxidizer and fuel) or a monopropellant (typically hydrazine). The system and method are particularly suited for resupply of satellites not originally prepared for refueling as well but the system may also be used for as satellites specifically designed for refueling.