Partitioned Data Storage Thermal Model

Description

The Partitioned Data Storage Thermal Model couples storage I/O activity to the spacecraft thermal network. It computes heat dissipation from idle power consumption plus energy expended during read and write operations, allowing the thermal system to model heat rejection from onboard data recorders. The model also provides optional overtemperature protection that can block write operations when temperature limits are exceeded.

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Example Use Cases

• Thermal Analysis: Model heat generation from data recorders during high-rate science data capture.
• Write Throttling: Simulate thermal protection behavior that blocks writes when storage overheats.
• Power-Thermal Budgeting: Correlate storage activity with power draw and thermal load.

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Module Implementation

Heat Dissipation

The thermal model computes power generation from three components: idle dissipation, read activity, and write activity.

The read and write power contributions are derived from the data rates and energy-per-byte coefficients:

$$P_{\text{read}}=E_{\text{read}}\cdot {\dot{B}}_{\text{read}}$$ $$P_{\text{write}}=E_{\text{write}}\cdot {\dot{B}}_{\text{write}}$$

where $E_{\text{read}}$ and $E_{\text{write}}$ are the energy dissipated per byte (in J/B), and ${\dot{B}}_{\text{read}}$ and ${\dot{B}}_{\text{write}}$ are the byte rates (in B/s) for the current time step.

The total power generation is:

$$P_{\text{total}}=P_{\text{idle}}+P_{\text{read}}+P_{\text{write}}$$

An optional maximum thermal power cap can limit the total if configured.

Default Energy Coefficients

The model uses tunable engineering coefficients representative of solid-state storage:

Parameter	Default Value	Description
Idle Power	0.5 W	Standby dissipation
Read Energy	50 nJ/B	Energy per byte read
Write Energy	200 nJ/B	Energy per byte written

Write operations typically dissipate more energy than reads due to flash program/erase cycles.

Overtemperature Protection

The model monitors temperature against a configurable threshold using hysteresis:

$$\text{Overtemperature}=\{\begin{array}{ll}\text{true}& \text{if }T>T_{\text{threshold}}\\ \text{false}& \text{if }T<T_{\text{threshold}}-T_{\text{hyst}}\end{array}$$

The default threshold is 358.15 K (85°C) with 10 K hysteresis. When thermal protection is enabled and the storage is in an overtemperature state, write operations can be blocked to reduce heat generation and allow cooling.

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Assumptions/Limitations

• The energy-per-byte coefficients are tunable engineering parameters, not physics-exact flash models.
• All dissipated energy is deposited into a single thermal node; internal gradients within the storage device are not modeled.
• Read and write power are computed from step-averaged data rates; instantaneous burst behavior is smoothed.
• Thermal protection only blocks writes; read operations continue regardless of temperature.
• The idle power is constant and does not vary with temperature or device state.