Variable Emissivity Perovskite Coatings for Spacecraft Thermal Control
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Solution Overview
Problem
Existing temperature control methods for spacecraft, such as thermal louvers and white coatings, are heavy, power-intensive, and prone to failure, and fail to effectively manage temperature extremes, leading to stress on critical components.
Innovation Solution
A tunable variable emissivity material with a perovskite oxide structure, represented by M1(1−(x+y))M2xM3yMnO3, where M1 is lanthanum, scandium, yttrium, praseodymium, or samarium, and M2 and M3 are specific alkali earth metals, which undergoes a phase transition at a critical temperature (Tc) between 270K to 320K, altering its emissivity and self-regulating temperature.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If thermal louvers are used to moderate spacecraft temperature, then temperature control is improved, but weight increases and reliability decreases
Solution Approach 1:
The coating material automatically adjusts its emissivity in response to temperature changes, with no external control system required. The material self-regulates the spacecraft temperature by changing its radiative properties when transitioning between ferromagnetic and paramagnetic states at the critical temperature.
Solution Approach 2:
The patent replaces the mechanical louver system with a passive coating material that achieves temperature control through intrinsic magnetic and radiative properties, eliminating moving parts and mechanical actuation systems.
2Temperature
If thermal louvers are used to moderate spacecraft temperature, then temperature control is improved, but power consumption increases
Solution Approach 1:
The coating material automatically adjusts its emissivity in response to temperature changes, with no external control system required. The material self-regulates the spacecraft temperature by changing its radiative properties when transitioning between ferromagnetic and paramagnetic states at the critical temperature.
Solution Approach 2:
The patent replaces the mechanical louver system with a passive coating material that achieves temperature control through intrinsic magnetic and radiative properties, eliminating moving parts and mechanical actuation systems.
3Object-affected harmful factors
If white coating is applied to spacecraft surface, then solar radiation absorption is reduced, but temperature fluctuations increase
Solution Approach 1:
The coating's emissivity parameter dynamically changes in response to temperature variations. At temperatures below the critical point, the material maintains low emissivity to retain heat; above the critical temperature, emissivity increases to enhance radiative cooling, thereby stabilizing temperature fluctuations.
Solution Approach 2:
The material undergoes a phase transition at its critical temperature, changing from a ferromagnetic state with low emissivity to a paramagnetic state with high emissivity. This phase change enables the coating to automatically adjust its thermal radiation properties in response to temperature variations.
4Weight of moving object
If variable emissivity material is used for temperature control, then weight is reduced, but manufacturing complexity increases
Solution Approach 1:
The patent employs composite material structures combining ferromagnetic particles embedded in a matrix material. This composite approach enables the desired magnetic and radiative properties while facilitating manufacturing through established composite material fabrication techniques.
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 material efficiently radiates heat above Tc, cooling the spacecraft, and retains heat below Tc, providing passive temperature control without additional power, reducing weight and operational stress on components.
Implementation Method 1
The material has a critical temperature (Tc) in the range of about 270 to about 320K and a transition width less than about 30K
Implementation Method 2
the material tends to self-regulate its temperature near Tc, radiating heat at temperatures above Tc and retaining heat below Tc
Implementation Method 3
The coating is designed to absorb very little solar radiation, yet radiate thermal energy in the infrared spectrum, thus biasing the overall temperature of the satellite structure on which it is disposed towards cooler temperatures
Data Source
AI summary
Tunable variable emissivity materials, methods for fabricating tunable variable emissivity materials, and methods for controlling the temperature of a spacecraft using tunable variable emissivity materials have been provided. In an exemplary embodiment, a variable emissivity material has the formula M1(1−(x+y))M2xM3yMnO3, wherein M1 comprises lanthanum, praseodymium, scandium, yttrium, neodymium or samarium, M2 comprises an alkali earth metal, M3 comprises an alkali earth metal that is not M2, and x, y, and (x+y) are less than 1. The material has a critical temperature (Tc) in the range of about 270 to about 320K and a transition width is less than about 30K.