1. When temperature, vacuum, and misalignment combine
Sebastian Junger’s The Perfect Storm returns because the thermal-vacuum test is another case where several ordinary factors add up to an extraordinary load. A small translation error, a hot soak, and a hard vacuum are each survivable. Together they can bind a guide pin, open a thermal joint, or arc a connector.
This entry defines the thermal-vacuum test matrix for the attachment interface.
2. Environmental bounds
The test chamber must reproduce the desktop’s orbit:
- Pressure: less than 10⁻⁵ torr, representative of LEO vacuum.
- Temperature range: −100°C to +100°C for non-operational survival, −40°C to +80°C for operational mating.
- Thermal ramp rate: 1 to 3°C per minute, bracketing expected orbital transitions.
- Number of cycles: at least 20 full temperature cycles with at least one mate/demate per cycle.
These bounds are conservative. They can be tightened once the actual orbit and thermal model are fixed.
3. The test matrix
| Case | Temperature | Alignment | Activity |
|---|---|---|---|
| Baseline | +20°C | Nominal | Mate, measure, demate |
| Cold operational | −40°C | Nominal | Mate, measure, demate |
| Hot operational | +80°C | Nominal | Mate, measure, demate |
| Cold survival | −100°C | Nominal | Survive, return to operational, mate |
| Hot survival | +100°C | Nominal | Survive, return to operational, mate |
| Cold + misalignment | −40°C | Off-nominal from Entry 398 | Mate, measure, demate |
| Hot + misalignment | +80°C | Off-nominal from Entry 398 | Mate, measure, demate |
| Life cycling | 20 cycles −40°C to +80°C | Nominal and off-nominal | Mate/demate at extremes |
The off-nominal cases reuse the translation and tilt errors defined in Entry 398.
4. What is measured
For each case the test records:
- Whether the cell fully seats and latches.
- Insertion and extraction force.
- Electrical continuity and pin resistance.
- Thermal interface resistance.
- Retention force after mating.
- Visual inspection for galling, cold welding, coating damage, or connector wear.
5. What this changes
- The thermal-vacuum test has a concrete matrix.
- The matrix links back to the off-nominal alignment cases from Entry 398.
- The next entry will define pass and fail criteria.