Humidity sensors that function under extreme conditions are needed in experimental chambers as well as for humidity measurements on Mars. Such a sensor was already used in a chamber at the German Aerospace Center and is well characterized; however this sensor is no longer in production and has been replaced by a new generation, requiring verification of the new sensor under extreme conditions. The results show that the new sensor is suitable for measurements under Martian atmospheric conditions.

Low-cost sensors could fill gaps in existing observation networks. To ensure data quality, the quality of the factory calibration of a given sensor has to be evaluated if the sensor is used out of the box. Here, the factory calibration of a widely used low-cost rain gauge type has been tested both in the lab (66) and in the field (20). The results of the study suggest that the calibration of this particular type should at least be checked for every sensor before being used.

Heat storage in the soil is difficult to measure due to vertical heterogeneity. To improve measurements, we designed a 3D-printed probe that uses fiber-optic distributed temperature sensing to measure a vertical profile of soil temperature. We validated the temperature measurements against standard instrumentation. With the high-resolution data we were able to determine the thermal diffusivity of the soil at a resolution of 2.5 cm, which is much higher compared to traditional methods.

Manual chambers for soil respiration monitoring can be cost-effective yet rather accurate devices. The described chamber is relatively low in cost and entirely built from commercial parts, which makes it very accessible for almost everybody. Our chamber is robust, simple to operate, and very suitable for a large-scale punctual campaign and for educational purposes. Oxygen sensors bring some more insights into our soil respiration understanding.

Soil moisture monitoring is important for many applications, from improving weather prediction to supporting agriculture practices. Our capability to measure this variable is still, however, limited. In this study, we show the tests conducted on a new soil moisture sensor at several locations. The results show that the new sensor is a valid and compact alternative to more conventional, non-invasive soil moisture sensors that can pave the way for a wide range of applications.