L2-PTC-MLI ESSENTIAL THERMAL Level 2 · hardware

Multi-Layer Insulation

Multi-Layer Insulation Blanket System

The Multi-Layer Insulation Blanket System is a passive thermal barrier comprising 15 to 30 alternating layers of aluminized Kapton film and low-conductance Dacron net spacers wrapped around the exterior of the Ark structure. Operating with zero power consumption, the assembly minimizes radiative heat exchange with the lunar vacuum, achieving an effective emissivity below 0.01. Maintaining this performance is challenged by lunar dust adhesion, which degrades outer-layer reflectivity, and by structural expansion during extreme thermal cycling. Furthermore, continuous exposure to solar ultraviolet radiation and particle radiation induces substrate degradation and fatigue in the aluminized films over the system's 100-year operational lifetime.

Multi-layer insulation blankets comprising alternating layers of aluminized reflective film and low-conductance spacers, minimizing radiative heat loss from the Ark's thermal envelope.

Purpose

Reduces radiative heat exchange between the Ark interior and the lunar vacuum environment to manageable levels, forming the primary passive insulation barrier.

Context

Wraps the exterior of the Ark structure, working with thermal coatings (L2-PTC-COAT) on exposed surfaces and providing the insulation against which heat pipes (L2-PTC-HPIPE) and PCM (L2-PTC-PCM) operate.

Principles

▸Each MLI layer reduces radiative heat transfer by reflecting infrared radiation
▸Low-conductance spacers minimize solid conduction between reflective layers
▸Effective emissivity decreases with number of layers, following diminishing returns
▸MLI performance is highly sensitive to compression, penetrations, and edge effects

Typical implementations

▸10-30 layers of aluminized Kapton or Mylar with Dacron net spacers
▸Beta cloth or Germanium-coated Kapton outer layer for micrometeorite protection
▸Grommeted and laced attachment to avoid compression
▸Venting provisions to prevent gas trapping during launch depressurization

Lunar considerations

▸Lunar dust adhesion to outer MLI layer degrades reflective performance
▸UV and particle radiation degrade polymer substrate over 100 years
▸Thermal cycling fatigue of aluminized coatings on polymer substrates
▸MLI must accommodate structural thermal expansion/contraction
▸No atmospheric drag means blankets can be designed without aerodynamic constraints

Specifications

Functional

primary function	Minimize radiative heat transfer between Ark interior and lunar vacuum environment
inputs	Radiative flux from lunar surface and solar environment
outputs	Insulated thermal boundary reducing heat loss/gain
effective emissivity	<0.01
layer count	15-30 layers typical
coverage	all non-radiator exterior surfaces

Physical

materials	Aluminized Kapton (0.25 mil), Dacron net spacers, Beta cloth outer layer, Stainless steel grommets
vacuum	True
radiation exposed	True
dust exposed	True

Operational

power consumption w	0
thermal range c	-173, 127
lifetime years	100

Interfaces

Provides

→Passive Thermal ControlRadiative insulationessential
Provides low-emissivity thermal barrier reducing radiative heat exchange with environment

Requires

←Primary StructureMounting surfaceessential
Structural exterior surface for blanket attachment via standoffs and grommets
←Dust MitigationDust mitigationessential
Dust removal or prevention to maintain outer layer reflective properties