Initial Results of the Relative Humidity Observations by MEDA Instrument Onboard the Mars 2020 Perseverance Rover

The Mars 2020 mission rover “Perseverance”, launched on 30 July 2020 by NASA, landed successfully 18 February 2021 at Jezero Crater, Mars (Lon. E 77.4509° Lat. N 18.4446°). The landing took place at Mars solar longitude Ls = 5.2°, close to start of the northern spring. Perseverance's payload in...

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Bibliographic Details
Published in:Journal of geophysical research. Planets 2023-02, Vol.128 (2), p.n/a
Main Authors: Polkko, J., Hieta, M., Harri, A.‐M., Tamppari, L., Martínez, G., Viúdez‐Moreiras, D., Savijärvi, H., Conrad, P., Zorzano Mier, M. P., La Torre Juarez, M., Hueso, R., Munguira, A., Leino, J., Gómez, F., Jaakonaho, I., Fischer, E., Genzer, M., Apestigue, V., Arruego, I., Banfield, D., Lepinette, A., Paton, M., Rodriguez‐Manfredi, J. A., Sánchez Lavega, A., Sebastian, E., Toledo, D., Vicente‐Retortillo, A.
Format: Article
Language:English
Subjects:
Absolute humidity
Adsorption
Adsorptivity
Advection
Air temperature
Atmosphere
Atmospheric models
Habitability
Humidity
Humidity measurement
Hydrologic cycle
instrument performance
Mars
Mars craters
Mars environment
Mars missions
Mixing ratio
near surface
Night
observations
Pressure sensors
Relative humidity
Sensors
Soil water
Soils
Solar longitude
Spring
Spring (season)
Sunrise
Water vapor
Water vapor content
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Summary:The Mars 2020 mission rover “Perseverance”, launched on 30 July 2020 by NASA, landed successfully 18 February 2021 at Jezero Crater, Mars (Lon. E 77.4509° Lat. N 18.4446°). The landing took place at Mars solar longitude Ls = 5.2°, close to start of the northern spring. Perseverance's payload includes the relative humidity sensor MEDA HS (Mars Environmental Dynamics Analyzer Humidity Sensor), which operations, performance, and the first observations from sol 80 to sol 410 (Ls 44°–210°) of Perseverance's operations we describe. The relative humidity measured by MEDA‐HS is reliable from late night hours to few tens of minutes after sunrise when the measured humidity is greater than 2% (referenced to sensor temperature). Data delivered to the Planetary Data System include relative humidity, sensor temperature, uncertainty of relative humidity, and volume mixing ratio (VMR). VMR is calculated using the MEDA‐PS pressure sensor values. According to observations, nighttime absolute humidity follows a seasonal curve in which release of water vapor from the northern cap with advancing northern spring and summer is visible. At ground level, frost conditions may have been reached a few times during this season (Ls 44°–210°). Volume mixing ratio values show a declining diurnal trend from the midnight toward the morning suggesting adsorption of humidity into the ground. Observations are compared with an adsorptive single‐column model, which complies with observations and confirms adsorption. The model allows estimating daytime VMR levels. Short‐term subhour timescales show large temporal fluctuations in humidity, which suggest vertical and spatial advection. Plain Language Summary The Mars 2020 mission rover “Perseverance” landed successfully on 18 February 2021 at Jezero Crater, Mars. The rover's payload includes a versatile instrument suite which includes a relative humidity sensor, whose observations for the first 410 Martian days are described here. The observations show how the lowest level of atmosphere is generally dry but still exceeding saturation is feasible because of cold nights. Sensor operations and accuracy estimates are presented. Relative humidity together with MEDA pressure and air temperature observations allow calculating absolute water vapor content of air at the sensor level at nighttime. Humidity observations are also compared with models describing water vapor adsorption and desorption into and out from soil. The results show how atmospheric humi
ISSN:2169-9097
2169-9100
DOI:10.1029/2022JE007447