EGU22-7888, updated on 28 Mar 2022
EGU General Assembly 2022
© Author(s) 2022. This work is distributed under
the Creative Commons Attribution 4.0 License.

Accuracy of the relative humidity sensor MEDA HS onboard Perseverance rover

Maria Hieta1, Jouni Polkko1, Iina Jaakonaho1, Maria Genzer1, Shahin Tabandeh2, José Antonio Rodríguez Manfredi3, Leslie Tamppari4, and Manuel de la Torre Juarez4
Maria Hieta et al.
  • 1Finnish Meteorological Institute, Space research and observation technologies, HELSINKI, Finland (
  • 2VTT Technical Research Centre of Finland Ltd, National Metrology Institute VTT MIKES, P.O. Box 1000, FI-02044 VTT, Finland
  • 3Centro de Astrobiología (INTA-CSIC), Madrid, Spain
  • 4Jet Propulsion Laboratory/California Institute of Technology, Pasadena, CA, USA

MEDA HS is the relative humidity sensor on the Mars 2020 Perseverance rover provided by the Finnish Meteorological Institute (FMI). The sensor is a part of Mars Environmental Dynamic Analyzer (MEDA), a suite of environmental sensors provided by Centro de Astrobiología in Madrid, Spain.

The accuracy requirement for MEDA HS relative humidity was ±10% RH for temperatures above -70 ºC, and ±20% RH for temperatures between -83...-73 ºC. Dynamic range from 0 to 100% RH shall cover the whole Martian temperature range from -83 ºC to -3 ºC. However it must be noted that during the daytime when the relative humidity drops close to zero, the readings are not scientifically meaningful due to the large relative uncertainty.

MEDA HS flight model was tested and calibrated in Mars-like dry environment at FMI together with flight spare and ground reference models from +22 ºC to -70 ºC and in saturation conditions from -40 ºC down to -70 ºC. Further, the MEDA HS flight model final calibration is complemented by calibration data transferred from an identical ground reference model which has gone through extensive humidity calibration test campaign at DLR PASLAB. The MEDA HS has been calibrated to full relative humidity range between -70 to -40 ºC in CO2 in the pressure ranges from 5.5 to 9.5 hPa, representative of Martian surface atmospheric pressure, and partial range up to +22 ºC. For lower temperatures the results are extrapolated.

The complex analysis of the MEDA HS measurement uncertainty has now been finalized and the results are presented in the conference. It has been found that the sensor exceeds the design requirements and will provide high accuracy relative humidity measurements from the Martian surface to provide important meteorological observations and to support MEDA and other M2020 investigations.

How to cite: Hieta, M., Polkko, J., Jaakonaho, I., Genzer, M., Tabandeh, S., Rodríguez Manfredi, J. A., Tamppari, L., and de la Torre Juarez, M.: Accuracy of the relative humidity sensor MEDA HS onboard Perseverance rover, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-7888,, 2022.


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