Optical Solar Reflector
Quartz/Silver OSR Tiles for Maximum Radiator Performance
Optical solar reflectors are fused quartz tiles with a silver back-coating mounted to thermal radiator panels to maximize heat rejection into space. By pairing a low solar absorptance of 0.07 with a high infrared emittance of 0.8, these second-surface mirrors achieve an absorptance-to-emittance ratio of 0.08, minimizing solar heat gain while radiating internal thermal loads. On the Moon, abrasive regolith dust deposits onto the quartz surface, degrading optical performance over time. Radiator assemblies require edge sealing to prevent lunar dust ingress between the tiles and the substrate, alongside replaceable tile configurations to manage contamination.
Quartz-silver Optical Solar Reflector (OSR) tiles providing the lowest available solar absorptance (~0.07) for radiator panels needing maximum heat rejection.
Purpose
Quartz-silver Optical Solar Reflector (OSR) tiles providing the lowest available solar absorptance (~0.07) for radiator panels needing maximum heat rejection.
Context
Child of L2-PTC-COAT within the Lunar Ark system
Principles
- ▸Fused quartz with silver back-coating: alpha = 0.06-0.08, epsilon = 0.78-0.82
- ▸Best alpha/epsilon ratio of any flight coating (~0.08)
- ▸Tile-based application; gaps filled with white coating
- ▸Long-life proven on commercial GEO satellites
- ▸Used on highest-priority radiators (cryocooler waste heat)
Typical implementations
- ▸Optical Coatings Lab Inc OSR tiles (heritage)
- ▸Hughes Aircraft second-surface mirror tiles
- ▸GEO satellite radiator panels
Lunar considerations
- ▸Lunar dust degrades OSR performance — coupled to L1-DST
- ▸Replaceable tiles via L1-MNT
- ▸Edge sealing prevents lunar dust ingress between tile and substrate
Specifications
Functional
| primary function | Quartz-silver Optical Solar Reflector (OSR) tiles providing the lowest available solar absorptance (~0.07) for radiator panels needing maximum heat rejection. |
| alpha solar | 0.07 |
| epsilon ir | 0.8 |
Physical
| mass kg | 15 |
| materials | Fused quartz tile, Silver back-coating, RTV silicone adhesive |
| vacuum compatibility | True |
Operational
| power consumption w | 0 |
| thermal range c | -40, 70 |
| lifetime years | 50 |
| mtbf hours | 1000000 |
Interfaces
Provides
- Premium radiator surface
- Cryocooler radiator surface
Requires
- Tile replacement
- Dust mitigation
Cite this entry
Lunar Ark Codex. "Optical Solar Reflector" (L3-PTC-COAT-OSR). Retrieved 10 September 2026, from https://lunarark.com/entry/L3-PTC-COAT-OSR
Licensed CC-BY-SA 4.0. You may reuse and adapt this entry with attribution, under the same licence.