NASA Ames Research Center, Moffett Field, California 94035, USA.
AMA Inc. at NASA Ames Research Center, Moffett Field, California 94035, USA.
Rev Sci Instrum. 2023 Feb 1;94(2):025002. doi: 10.1063/5.0129703.
The total heat flux sensors for NASA's Mars Entry, Descent, and Landing Instrumentation 2 (MEDLI2) sensor suite on the Mars 2020 vehicle and the Low-Earth Orbit Flight Test of an Inflatable Decelerator (LOFTID) technology demonstration mission are passively cooled Schmidt-Boelter gauges. The output of these sensors has been experimentally demonstrated to be dependent on the temperature of the sensing element. The experimental results are shown to align with a model that assumes temperature-dependent material properties, specifically the Seebeck coefficient. The MEDLI2 and LOFTID flight total heat flux sensors did not undergo a full thermal calibration prior to being installed on the flight vehicles since the temperature dependence was unknown ahead of time. Additionally, the material properties are not known due to the designs being proprietary. For these reasons, an approximate correction factor was derived. The applicability and associated uncertainty of this temperature-dependent correction factor are presented. The error that would be introduced into the measurement if temperature effects were not accounted for would be as high as 9.5% and 16% for the MEDLI2 and LOFTID total heat flux sensors, respectively. As a best practice for future flight missions and ground-based applications that employ similar passively cooled heat flux sensors, it is recommended to individually calibrate each sensor across all applicable use temperatures to account for sensor-to-sensor variations and minimize measurement uncertainty.
美国宇航局火星进入、下降和着陆仪器 2（MEDLI2）传感器套件的总热通量传感器和可膨胀减速器的低地球轨道飞行试验（LOFTID）技术演示任务的总热通量传感器是被动式冷却的施密特-波尔计规。这些传感器的输出已通过实验证明与假设温度相关的材料特性（尤其是塞贝克系数）的模型有关。由于事先不知道温度依赖性，因此在安装到飞行载具之前，MEDLI2 和 LOFTID 飞行总热通量传感器并未进行全面的热校准。此外，由于设计是专有的，因此不知道材料特性。出于这些原因，推导出了一个近似修正因子。介绍了这种温度相关修正因子的适用性和相关不确定性。如果不考虑温度影响，将对测量结果引入的误差对于 MEDLI2 和 LOFTID 总热通量传感器而言，分别高达 9.5%和 16%。作为未来飞行任务和采用类似被动式冷却热通量传感器的地面应用的最佳实践，建议在所有适用的使用温度下对每个传感器进行单独校准，以消除传感器之间的差异并最大程度地降低测量不确定性。
