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Thermal Testing Purpose and Overview

Thermal testing needed to occur due to the temperature that the camera and other components will reach in near-space environment. Decreased temperatures may cause complications in areas such as structural, power, or imagery capture.

Atmospheric thermodynamics is quite different than thermodynamics at sea level. The complexity of an open system is extremely difficult; therefore, in atmospheric thermodynamics open system interactions are neglected and closed systems are the default assumption. A closed system can exchange heat and energy with its surroundings but not matter. Thus, our system (payload) was considered a closed system for testing purposes.

The image on the right was taken from Lutgens and Tarbuck (The Atmosphere, 8th edition) showing vertical profiles of the atmosphere.

The temperature ranges that need to be tested ranged from approximately 23ºC at ground level to –60ºC in the stratospheric atmosphere. These are the most extreme temperatures that GEOCAM could experience during flight.

Operational Temperatures

Thermal testing was intended to prove that the GEOCAM payload would survive near space temperatures. The basic mechanics of the payload were completed and assembled with no new components assumed to be added. Understanding the operation temperatures of the assembled components improved efficiency and helped to determine of the amount of insulation needed.

Once the temperature limitations were found, each component was evaluated for the amount of thermal protection needed during flight. Insulation was used to retain heat dispensed from the components in order to stabilize the fluctuation in temperature that GEOCAM would experience. Heaters were also added to help keep all components within operation range.

The outside of the GEOCAM structure was also insulated and coated with white tape to reflect some of the sun’s light. This was needed because if the outside coating was metallic or black (as was the color of the insulation used on the outside of the box), the sun could heat the casing too much, and cause the components inside to overheat.