The Pressure sensor measures atmospheric pressure in the range of 0 – 1400 Pa with beginning-of-life accuracy circa 3 Pa. Its relative accuracy (repeatability in the time scale of hours) is less than 2 Pa and resolution max. 0.2 Pa.
The Pressure sensor is provided by the Finnish Meteorological Institute, and it is based on proprietary technology of Vaisala, Inc. Pressure observations make use of Vaisala Barocap® pressure sensor heads and Thermocap® temperature sensor heads. The measurement is based on capacitor plates (electrodes) moved by the pressure, thus changing the capacitance of the sensor head.The Pressure sensor contains two types of Barocap® sensor heads: 1 of high-stability type, and 3 of high-resolution type.
The control of the sensor is based on a low-power transducer controlled by the dedicated ASIC, which is in turn controlled by the FPGA in the REMS Instrument Control Unit. The Pressure sensor has two separate transducers that can be used in turn, adding to the reliability of the sensor.
The transducer electronics and the sensor heads are placed on a single multi-layer PCB protected by box-like Faraday cages made of FR4 material. The sensor is located inside REMS control box (ICU) in a temperature-regulated compartment inside the rover body. The contact to the atmosphere is provided through ventilation tube that ends in a “chimney”. In order to avoid contamination of the Mars environment, and on the other hand to avoid dust deposition inside the sensor, the opening of the “chimney” is protected with membrane filter.
The general characteristics of the Pressure sensor are given in the table below.
- Dimensions (excl. ventilation pipe) 60 x 52 x 17 mm
- Mass 35 g
Power consumption 15 mW
- Data rate 216 bits/s, 1.5 Mbits/sol
- Operational temperature 228 – 328 K
- Measurement range 0 – 1400 Pa
- Relative accuracy (= repeatability in the time scale of hours)
- Total accuracy of daily averaged readings (beginning-of-life) ~ 3 Pa
- Stability (= drift rate)
- Resolution 0.2 – 0.3 Pa
Pressure Sensor (PS)