Innovators at NASA Johnson Space Center have developed a thin film sensor that measures temperatures up to 1200 °F, and whose prototype successor may achieve measurements up to ~3000 °F — which was the surface temperature of the Space Shuttle during its atmospheric reentry.
The novel sensor design also quells the deleterious effects of thermal expansion mismatch between the thermal protection system (TPS) material comprised in the spacecraft’s outer shell, and the embedded thin film sensors’ component materials.
Current methods that capture temperature data from the surface of a reentering spacecraft typically rely upon the use of low frequency thermocouples embedded in the spacecraft’s TPS and are limited to ~700 °F. However, these thermocouples lack the high frequency response required for anything but low frequency temperature or heat flux. This novel thin-film temperature sensor, also embedded as an in-situ device in the through-thickness of a spacecraft’s TPS, is designed to solve these issues by capturing data at an extremely high frequency rate (>1MHz).
The thin film sensor’s principal advantage lies in its potential to take high frequency temperature measurements from the surface of a reentering spacecraft while simultaneously withstanding the high temperature and oxidizing environment encountered. This data provides engineers with operational phase measurements used to refine the spacecraft’s operational envelope and track flight hardware behavior in addition to providing high frequency temperature measurements that can inform the physics of a boundary layer.
Mismatches in coefficients of thermal expansion (CTE) are expected in TPS-based sensor applications because the metallic materials used for temperature sensing have thermal expansion rates that differ from the rates of the substrate and coating materials in the TPS. At high temperatures during reentry, this mismatch in CTE can create a significant strain differential between the metallic sensor, sensor leads, and the materials to which the sensor and leads are bonded.
This technology may prove extremely useful in a burgeoning commercial aerospace industry where the ability to measure temperature from the surface of a reentering spacecraft can be used to enhance performance and safety. The thin film temperature sensor may also have commercial applications in hypersonic aircraft, energy production, metallurgical blast furnaces, and other extreme high enthalpy environments.
NASA is actively seeking licensees to commercialize this technology. Please contact NASA’s Licensing Concierge at
