Measurement Principle and Equipment for Measuring Humidity Contents in the Upper Martian Surface and Subsurface

In-situ measurements of the water vapour content in atmosphere and surface are required for the better understanding of the physical, chemical, and possibly also exobiological processes in the upper Martian surface. The method measures the water vapour content coulometrically in the range between saturation and dew point temperatures less than -90°CTd. The typical sensor characteristics are: low energy consumption, low data rates, very small dimensions by miniaturization, less weight, very robust packaging. A chamber simulates time profiles of humidity and temperature. Therefore the measuring system includes generators for humidity, temperature, gas contents and pressures, a gasdryer and –mixer, a regulated freezing box and a possibility for the creation of underpressure within the freezing box. The measuring capabilities are kept universal for the planned experiments to reach a maximum of suitability for the desired hardware configuration. A specific electronic managing and logging system has been developed and manufactured. It permits high integration possibilities into other existing measurement systems.