On-orbit Propellant Metering with Active Thermal Control
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Solution Overview
Problem
Current on-orbit propellant transfer techniques suffer from low measurement accuracy, typically around +/-2%, leading to potential over- or under-supply of propellants in spacecraft refueling.
Innovation Solution
A system with a first spacecraft equipped with a fluid storage arrangement, a flow meter, and an active thermal control arrangement that maintains the flow meter and holding tank within a specified temperature range, reducing measurement error to +/-1% by using an isothermal mounting panel, heat pipes, and thermostatically controlled heaters or coolers, and pressure regulation modules to accurately transfer propellants and pressurants to a second spacecraft.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional on-orbit propellant transfer techniques are used, then the transfer operation can be performed, but the measurement accuracy is low (typically +/-2%)
Solution Approach 1:
The patent applies parameter changes by controlling the temperature of the flow meter and holding tank within a specified range using an active thermal control arrangement. This temperature control stabilizes the physical properties of the propellant and improves the measurement accuracy of the flow meter from +/-2% to +/-1% or better, directly resolving the measurement precision issue in on-orbit propellant transfer
Solution Approach 2:
The patent introduces an intermediary holding tank between the propellant storage and the client spacecraft. This holding tank, equipped with temperature control, acts as a buffer that stabilizes the propellant conditions before transfer, enabling more accurate flow measurement and improving overall refueling precision through this intermediate stabilization stage
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 system achieves high measurement accuracy in propellant transfer, mitigating the risks of over- or under-supply and ensuring precise refueling of spacecraft, thereby improving the reliability of spacecraft operations.
Implementation Method 1
The active thermal control arrangement may include an isothermal mounting panel, one or more heat pipes and a thermostatically controlled heater
Implementation Method 2
a thermostatically controlled heater
Implementation Method 3
a flow meter disposed proximate to the holding tank
Implementation Method 4
each regulator module including a pressure regulator and a control valve. In some examples, the regulator modules may be configured to deliver pressurant from the pressurant tank to the holding tank at a selectable regulated pressure
Data Source
AI summary
A first spacecraft includes a first fluid storage arrangement and a fluid flow metering arrangement including a holding tank coupled with the first fluid storage arrangement, a flow meter disposed proximate to the holding tank, and an active thermal control arrangement controlling the temperature of the flow meter and the holding tank. The first spacecraft is configured to service a second spacecraft, the second spacecraft including a second fluid storage arrangement, by transferring one or both of a propellant and a pressurant from the first fluid storage arrangement to the holding tank, and from the holding tank, through the flow meter, to the second fluid storage arrangement.