The athermal range is the temperature range over which the payload is expected to perform without significant degradation in image quality or mechanical stability. It is estimated from the component with the smallest athermalized range, which is essentially the component that is excepted to fail first, should its temperature fall below or rise above its athermal range.

$$ T_{system} = \min_{c \in C} c_{T} $$

Where

• $T_{system}$ : Athermal range of the system.
• $C$ : Set of all components in the system.
• $c_T$ : Athermal range of a component.