Thermal Assessment

Applicable Phases

• Primary: Phase A (first-order sizing), Phase B (preliminary thermal model)
• Supporting: Phase C (detailed model correlation), Phase D (TVAC test planning with ait-manager)

Analysis Domains

1. Environmental Heat Flux Calculation

Avoid hardcoded values — scale by mission:

• Solar flux ($G_s$): $1361\ W/m^2$ at 1 AU, scales as $1/d^2$.
• Albedo ($q_a$): $G_s \times a \times F_{view}$ (Earth albedo ~0.3, Moon ~0.12, Mars ~0.25).
• Planetary IR ($q_{IR}$): Based on body surface temperature and view factor.
• Deep space sink: 2.7 K cosmic microwave background.

2. Nodal Heat Balance

• Steady state: $Q_{in} + Q_{gen} = Q_{out}$
• Transient: $Q_{in} + Q_{gen} = Q_{out} + mc_p(dT/dt)$
• Conduction: $Q = kA\Delta T / L$
• Radiation: $Q = \epsilon\sigma A(T_1^4 - T_2^4)$
• Internal dissipation ($Q_{gen}$): Electronics waste heat, heater inputs.

3. Thermal Hardware Sizing

• MLI: Effective emissivity $\epsilon^*$ (typically 0.01-0.05 for good MLI).
• Radiators: Area from $Q_{reject} = \epsilon\sigma\eta A T^4$. Size for worst-case hot.
• Heaters: Power to maintain min temperature in worst-case cold.
• Heat pipes / loop heat pipes: For spreading heat from high-dissipation components.
• Thermal straps / isolators: Conductive coupling or decoupling between components.

4. Surface Properties

Note: these degrade with UV exposure and atomic oxygen over mission life (BOL vs EOL).

Verification & Margins

• Operational margin: 10°C buffer between predicted T and component hardware limits.
• Survival margin: 5°C buffer for non-operational states.
• Uncertainty: State assumptions for contact conductance and coating degradation (BOL vs EOL).

Output Format

1. Thermal Model Summary (thermal_model.md): Environment, nodes, heat loads, predicted temperature ranges, and margin status.
2. Material Recommendations: Surface treatments with $\alpha/\epsilon$ ratios.
3. Hardware List: Radiator area, heater power, MLI coverage, heat pipes.

Interface

• Reads from: /requirements/, /analysis/mission-analysis-specialist/ (eclipse duration, solar distance), /analysis/power-assessment/ (component dissipation), /analysis/structural-assessment/ (configuration)
• Writes to: /analysis/thermal-assessment/
• Consumed by: systems-engineering-assessment (thermal summary), power-assessment (battery temp limits, heater power), ait-manager (TVAC test limits), lunar-conops-manager (surface thermal environment)