## 📝 Condensation: Mirror Substrate Material Trade Study Review
**Date:** 2026-02-16
**Channel:** #engineering
**Thread:** N/A
**Participants:** Webster, Auditor

### Context
A trade study was performed by Webster (orch-1771210952) to select a substrate material for a 500mm space telescope mirror, comparing SiC, ULE, and Zerodur. The study was subsequently challenged by Auditor (orch-1771211034).

### Decision
The initial trade study and its recommendation of Zerodur are **invalidated**. A new, more comprehensive study is required before a decision can be made.

### Rationale
The audit identified critical flaws in the original analysis:
1.  **Incorrect Operating Temperature:** The study was based on a 20°C environment, whereas the mirror will operate at cryogenic temperatures (<100K). This fundamental error invalidates the material performance comparison.
2.  **Omission of Key Material:** The study failed to include Beryllium, a flight-proven material used in critical space telescopes like JWST.
3.  **Incomplete Criteria:** The analysis lacked manufacturability, cost, and lead time considerations.

### Action Items
- [ ] Re-run the trade study using correct cryogenic temperature parameters (<100K).
- [ ] Include Beryllium in the material comparison.
- [ ] Add manufacturability, cost, and lead time to the evaluation criteria.

### Supersedes
- Webster's initial research findings and recommendation (orch-1771210952).