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This work describes the qualification of MEMS differential pressure sensors to be used in a particle analyzer for Mars 2020. Two different types of sensors have been initially considered MEMS-33A-001D and NPH-8-002.5-GH, in order to select the most suitable in terms of S/N ratio and sensitivity. Sensors have been calibrated at ambient pressure using as reference a water column differential manometers, selected for the unmatchable stability, key property for tests expected to span across many days. The pressure signal has been generated using the water column manometer itself, allowing to reach the full scale of the instruments and by means of a vane pump in low pressure environment where a capacitive manometer has been used as reference. No variation in the sensor sensitivity has been evidenced after exposure to the expected temperature range for the instruments mounted on the platform of the ExoMars Lander. The final selection of the sensor to be flight-qualified has been made on the SNR because both candidates proved to be compatible with the mechanical loads expected during launch and Martian landing and the expected space environment through all mission phases.

This paper presents the design and validation of a volume flow measurement system developed to measure volume flowrate of gas at pressures below 1 kPa. The system had to be developed because a suitable commercial transducer was not available for the unusual working environment, where outgassing and sublimation phenomena become relevant for many materials and the rarefied atmosphere changes dramatically its heat and mass exchange parameters. The development of a low-pressure compatible measurement system comes from the need of measuring the flow rate of a rotary vane pump working under an environmental absolute pressure in the range between 600 and 1000 Pa, mostly composed by CO2 i.e. the average condition of the Martian atmosphere at the surface. The pump will be a key component of the MicroMED particle analyzer, an instrument of the ExoMars 2020 ESA-Roscosmos mission payload. The measurement system is based on a control volume, made by a stainless-steel bellow, which has been designed accounting for the environmental requirements and the expected flow rate. The measurement system has been calibrated at ambient condition and tests in low-pressure have been performed to validate the measurement system and to derive the flow rate characteristics of a pump mock-up at different environmental pressures.

Design of a flow meter to be used in a low-pressure environment is hereafter presented. The need of this activity comes from the lack of commercial flow meters operating at low pressures due to the unusual working environment, where outgassing and sublimation phenomena becomes relevant for many materials and rarefied atmosphere changes dramatically the heat and mass exchange phenomena. In our case, the need of a low pressure compatible measurement system comes from the need of measuring the flow rate of a rotary vane pump working under an environmental pressure between 10 and 6 mbar, simulating the condition of the Martian atmosphere at the surface. The pump will be the key component of a particle analyzer that should be part of the ExoMars 2020 ESA-Roscosmos mission. The designed measurement system is based on the deformation of a control volume, a stainless-steel bellow, which has been designed on the basis of the expected flow rate. The measurement system has been calibrated at ambient condition and testing in low-pressure has been performed in order to validate the measurement method and derive the flow rate performances within the expected working conditions.

Feasibility design of a damper based on superelastic shape memory alloys (SMAs) is presented. The design wants to develop a passive vibration insulator for the Contamination Assessment Microbalance instrument, a quartz crystal microbalance for monitoring and measuring contamination in space environment. The ability of SMAs to act as efficient vibration insulators comes from their pseudo-elastic capabilities as the hysteretic force versus displacement behavior allows for energy dissipation. A 3D model of the instrument was developed to perform modal and dynamic random analyses aimed to identify the insulator mechanical characteristics and verify the instrument mechanical resistance. Moreover, a setup was designed to measure superelastic damping capacity of a commercial pseudoelastic shape memory alloy wire in dynamic tensile mode. The wire' specific damping capacity was then tested in different conditions, i.e. changing the excitation frequency and the amplitude of the deformation within a range of interest. The experimental activity allowed validation of the selected SMA wire for the intended application.