Flexible Thermal-Control Material for Spacecraft

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Solution Overview

Problem

Flexible thermal-control materials used in space applications face challenges in achieving low solar absorptance coefficients and high total semi-sphere infrared emissivity, along with tolerance to radiation and atomic oxygen, which are not adequately met by existing technologies.

Innovation Solution

A flexible thermal-control material is developed by laminating a reflection layer with a high-reflectivity metal and an infrared radiation layer made of silicone material, optionally including adhesive, support, antioxidant, protection, and conductive layers, to enhance optical properties and durability in space environments.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Illumination intensity

If a metal layer is coated on a polyimide film with roughening treatment, then reflectivity and diffuseness are improved, but solar absorptance coefficient is not sufficiently reduced

Engineering Contradiction:

ImprovereflectivityVSAvoidsolar absorptance coefficient

Core Design Contradiction:

Illumination intensityVSObject-affected harmful factors

Solution Approach 1:

The thermal control coating is divided into multiple functional layers: a reflective layer (silver or aluminum) for high reflectivity, and a separate infrared radiative layer (silicone resin) for thermal radiation. This segmentation allows each layer to optimize its specific function without compromising the other, achieving both low solar absorptance and high infrared emissivity.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The invention uses a composite structure combining metal reflective layer with silicone resin infrared radiative layer. The metal provides excellent solar reflection, while the silicone resin adds infrared radiation capability and maintains flexibility. This composite material approach resolves the contradiction by integrating materials with complementary properties.

Inventive Principle:

Principle #40Composite materials

2Ease of operation

If a flexible thermal-control material is used in space, then ease of processing according to surface shape is improved, but tolerance to radiation and atomic oxygen is not sufficiently ensured

Engineering Contradiction:

Improveflexibility for surface processingVSAvoidtolerance to radiation and atomic oxygen

Core Design Contradiction:

Ease of operationVSReliability

Solution Approach 1:

The invention uses a flexible substrate (polyimide film) with thin coating layers to create a conformal thermal control material that can be easily applied to curved satellite surfaces. The flexibility is maintained while incorporating radiation-resistant materials and protective structures.

Inventive Principle:

Principle #30Flexible shells and thin films

Solution Approach 2:

The silicone resin infrared radiative layer serves as a protective cushioning layer that shields the underlying metal reflective layer from direct exposure to atomic oxygen and radiation in the space environment. This prior protection prevents degradation of the sensitive metal layer while maintaining the flexible structure.

Inventive Principle:

Principle #11Beforehand cushioning (Prior cushioning)

3Object-affected harmful factors

If a reflective layer is added to reduce solar absorptance, then solar absorptance coefficient is reduced, but infrared emissivity is not sufficiently increased

Engineering Contradiction:

Improvesolar absorptance coefficientVSAvoidinfrared emissivity

Core Design Contradiction:

Object-affected harmful factorsVSUse of energy by moving object

Solution Approach 1:

The coating structure is designed with different local properties: the metal reflective layer has high solar reflectivity for reducing solar absorptance, while the silicone resin infrared radiative layer has high infrared emissivity for thermal radiation. Each layer is optimized for its specific wavelength range, achieving both objectives simultaneously.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The invention addresses the contradiction by operating in different wavelength dimensions: the reflective layer targets the solar spectrum (visible and near-infrared) to reduce absorptance, while the infrared radiative layer targets the thermal infrared spectrum to enhance emissivity. This dimensional separation in spectral response allows both requirements to be met.

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

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 achieves excellent optical properties with a solar absorptance coefficient of 0.2 or less and total semi-sphere infrared emissivity of 0.8 or more, ensuring effective heat management and resistance to radiation and atomic oxygen, thereby preventing temperature increases in airframes.

Implementation Method 1

a reflection layer which reflects solar light

Methodology Applied

Scientific EffectReflection: Reflection

Implementation Method 2

an infrared radiation layer which radiates infrared light

Methodology Applied

Scientific EffectThermal radiation: Thermal Radiation

Data Source

PatentEP3015262B1Flexible thermal-control material

Publication Date: 2020.11.04 MITSUBISHI HEAVY IND LTD

Figure 1
Figure 2A~2B
Figure 3~4

AI summary

This flexible thermal-control material (10A) is obtained by stacking: a reflective layer (12) which reflects sunlight; and an infrared-ray emission layer (13) which emits infrared rays. The infrared-ray emission layer (13) is configured from a silicone material. Accordingly, a flexible thermal-control material is achieved which exhibits excellent optical characteristics such as solar absorption (α).