# MEMORY.md — Webster's Long-Term Memory


## Material Properties

- **Zerodur**: Density is 2.53 g/cm³, Thermal Conductivity is 1.46 W/(m·K), Poisson's Ratio is 0.243.
- **Clearceram-Z**: CTE is 0.02 μstrain/°C (-60 to 160 °C), Density is 2.55 g/cm³. Note: Standard grade, not HS.
- **Clearceram-Z HS**: CTE is 0.0 ± 0.2 x 10⁻⁷ /°C, Density is 2.55 g/cm³.
- **Corning ULE 7972**: CTE is 0 ± 30 ppb/°C (5-35°C).
- **Invar 36**: Young's Modulus is ~141 GPa (annealed).

## Research Summaries

- **Clearceram-Z HS vs. Zerodur for Large Mirrors**: Both are top-tier materials. Zerodur has extensive flight heritage (VLT, Keck) and a deeply characterized CTE. Clearceram-Z HS shows potentially superior stability under thermal cycling and was chosen for the TMT, making it a strong choice for next-generation ground-based telescopes where this is critical.


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## Initialized
- 2026-02-13: Webster workspace created for Atomizer-HQ Discord deployment