RTG Radiator Fins
RTG Waste Heat Rejection Fin Assembly
The RTG waste heat rejection fin assembly is a fin-tube radiator structure designed to reject approximately 1500 Wt of thermal waste to space, maintaining the cold-side temperature differential necessary for thermoelectric power generation. Operating in the lunar environment introduces significant thermal constraints: background infrared emission from the ~250 K lunar surface reduces radiator effectiveness relative to deep space, while regolith dust accumulation progressively degrades high-emissivity coatings (epsilon >0.85) applied to aluminum or carbon-carbon composite surfaces. Additionally, the assembly geometry must maximize view factors to deep space while resisting thermal fatigue across 100 years of continuous operation.
Radiator fins rejecting RTG waste heat to maintain thermoelectric cold-side temperature
Purpose
Reject ~1500Wt waste heat from RTG to space to maintain optimal thermoelectric temperature differential
Context
Child of L2-PWR-RTG within the Lunar Ark power generation system
Principles
- ▸Fin-tube radiator design maximizes surface area for radiative heat rejection
- ▸Stefan-Boltzmann law governs radiative heat transfer: Q = epsilon*sigma*A*T^4
- ▸High-emissivity coating (epsilon >0.85) maximizes heat rejection per unit area
- ▸Fin spacing and geometry optimized for view factor to deep space
Typical implementations
- ▸MMRTG 8-fin aluminum radiator design (heritage from Viking, Voyager era)
- ▸GPHS-RTG cylindrical fin radiator (Cassini, New Horizons)
- ▸ISS External Active Thermal Control System radiator panels
- ▸Advanced carbon-carbon radiator fin concepts for improved conductivity
Lunar considerations
- ▸Lunar surface IR emission (~250K) reduces radiator effectiveness compared to deep space
- ▸Dust accumulation on radiator fins degrades emissivity over time
- ▸Must be positioned to minimize thermal coupling to other Ark systems
- ▸Fin material must resist thermal fatigue over 100 years of continuous operation
Specifications
Functional
| primary function | Radiator fins rejecting RTG waste heat to maintain thermoelectric cold-side temperature |
Physical
| materials | Aluminum 6061 fins, Carbon-carbon composite (advanced), High-emissivity Aeroglaze Z306 coating |
Interfaces
Provides
- Cold-side heat rejection maintaining temperature differential
Requires
- Dust mitigation for radiator fin surfaces
Cite this entry
Lunar Ark Codex. "RTG Radiator Fins" (L3-PWR-RTG-RAD). Retrieved 10 September 2026, from https://lunarark.com/entry/L3-PWR-RTG-RAD
Licensed CC-BY-SA 4.0. You may reuse and adapt this entry with attribution, under the same licence.