Mars Science Laboratory relative humidity observations: Initial results

Abstract

The Mars Science Laboratory (MSL) made a successful landing at Gale crater early August 2012. MSL has an environmental instrument package called the Rover Environmental Monitoring Station (REMS) as a part of its scientific payload. REMS comprises instrumentation for the observation of atmospheric pressure, temperature of the air, ground temperature, wind speed and direction, relative humidity (REMS-H), and UV measurements. We concentrate on describing the REMS-H measurement performance and initial observations during the first 100 MSL sols as well as constraining the REMS-H results by comparing them with earlier observations and modeling results. The REMS-H device is based on polymeric capacitive humidity sensors developed by Vaisala Inc., and it makes use of transducer electronics section placed in the vicinity of the three humidity sensor heads. The humidity device is mounted on the REMS boom providing ventilation with the ambient atmosphere through a filter protecting the device from airborne dust. The final relative humidity results appear to be convincing and are aligned with earlier indirect observations of the total atmospheric precipitable water content. The water mixing ratio in the atmospheric surface layer appears to vary between 30 and 75 ppm. When assuming uniform mixing, the precipitable water content of the atmosphere is ranging from a few to six precipitable micrometers.Key PointsAtmospheric water mixing ratio at Gale crater varies from 30 to 140 ppmMSL relative humidity observation provides good dataHighest detected relative humidity reading during first MSL 100 sols is RH75%

Amorphous salts formed from rapid dehydration of multicomponent chloride and ferric sulfate brines: Implications for Mars

“…Though these low RH values are consistent with daytime RH values observed on the Martian surface (Harri et al, 2014;Savijarvi, 1995), and Martian surface temperatures can exceed 20°C at the equator (Spanovich et al, 2006), this combination of RH-T values represents a narrow range of current Martian conditions. However, the goal of this study is to explore whether amorphous products can form from mixed component brines under rapid precipitation conditions, which could occur through multiple pathways (described above).…”

Análisis de las condiciones ambientales en el cráter Gale a partir de mediciones REMS/MSL

“…We have also estimated the daily UV irradiation using dust opacity values derived from the Mastcam instrument. For more specific information on scientific results obtained from the different REMS sensors, the reader is referred to Harri et al (2014a), Haberle et al (2014), Kahanpää et al (2016) and Guzewich et al (2016) for the PS; Hamilton et al (2014), Martínez et al (2014) and Martínez et al (2015) for the GTS; Harri et al (2014b), Martín-Torres et al (2015), Savijärvi et al (2015a), Martínez et al (2015) and Savijärvi et al (2015b) for the RHS and Smith et al (2016) for the UVS. REMS has already provided the most comprehensive coverage of near-surface environmental conditions recorded by a spacecraft landed on Mars.…”

“…They are based on thermistors because of their robustness, with a typical response time less than 1 s. The relative humidity sensor (RHS) is located on boom 2 at about 1.6 m height. It is based on an active polymer film that changes its capacitance a function of the relative humidity (Harri et al, 2014b). The ultraviolet sensor (UVS) is located on the rover deck and is comprised of six photodiodes to measure the UV flux in different bands, one global in the range 200-380 nm named ABC and 5 filtered photodiodes in the range 320-380, 280-320, 200-280, 230-290 Figure 1.…”

Low Humidity Characteristics of Polymer-Based Capacitive Humidity Sensors

“…gases [8]), detection of a trace moisture content in natural gas pipelines, drying of solid materials, in meteorology [9] at high altitudes (climate change studies), or in cosmonautical observations [10,11], the measurement of low humidity is essential. Some companies meet that need with sensors dedicated to low humidity (e.g.…”