Humidity calibration of relative humidity devices in Martian conditions

Finnish Meteorological Institute (FMI) has developed relative humidity measurement devices for past and future Mars lander missions: REMS-H for Curiosity, MEDA HS for Mars 2020 and METEO-H for ExoMars 2020. The sensors used in these devices are HUMICAP® capacitive thin-film polymer sensors by Vaisala Inc. New calibration measurements are performed with ground reference models of these devices in the Mars Simulation Facility (MSF) and Planetary Analog Simulation Laboratory (PASLAB) at the German Aerospace Center (DLR) in spring 2020. The preliminary results will be given at the EGU 2020. Calibration of relative humidity devices requires in minimum two humidity points over the expected operational temperature and pressure range of the device. With two-point calibration the relative humidity devices can be used for scientific measurements with satisfactory quality but the uncertainty is notable. Stable humidity conditions between dry and saturation humidity in Martian conditions can be achieved reliably in very few laboratories in the whole world and humidity measurements in Martian conditions have been previously performed for the same devices in FMI laboratory and in Michigan Mars Environmental Chamber (MMEC) at the University of Michigan. The new measurement campaign will consist of stable humidity point measurements in multiple temperatures between +10°C to -70°C in CO2 gas and Martian pressure of approximately 7 hPa. The measurements are performed simultaneously for multiple devices in a small pressure vessel with continuous humidified carbon dioxide flow. The new measurement campaign will improve the characterization of the existing relative humidity devices in Mars lander missions and define in more detail the measurement uncertainties

The diverse meteorology of Jezero crater over the first 250 sols of Perseverance on Mars

NASA’s Perseverance rover’s Mars Environmental Dynamics Analyzer is collecting data at Jezero crater, characterizing the physical processes in the lowest layer of the Martian atmosphere. Here we present measurements from the instrument’s first 250 sols of operation, revealing a spatially and temporally variable meteorology at Jezero. We find that temperature measurements at four heights capture the response of the atmospheric surface layer to multiple phenomena. We observe the transition from a stable night-time thermal inversion to a daytime, highly turbulent convective regime, with large vertical thermal gradients. Measurement of multiple daily optical depths suggests aerosol concentrations are higher in the morning than in the afternoon. Measured wind patterns are driven mainly by local topography, with a small contribution from regional winds. Daily and seasonal variability of relative humidity shows a complex hydrologic cycle. These observations suggest that changes in some local surface properties, such as surface albedo and thermal inertia, play an influential role. On a larger scale, surface pressure measurements show typical signatures of gravity waves and baroclinic eddies in a part of the seasonal cycle previously characterized as low wave activity. These observations, both combined and simultaneous, unveil the diversity of processes driving change on today’s Martian surface at Jezero crater.This work has been funded by the Spanish Ministry of Economy and Competitiveness, through the projects no. ESP2014-54256-C4- 1-R (also -2-R, -3-R and -4-R); Ministry of Science, Innovation and Universities, projects no. ESP2016-79612-C3-1-R (also -2-R and -3-R); Ministry of Science and Innovation/State Agency of Research (10.13039/501100011033), projects no. ESP2016-80320-C2-1-R, RTI2018-098728-B-C31 (also -C32 and -C33), RTI2018-099825-B-C31, PID2019-109467GB-I00 and PRE2020-092562; Instituto Nacional de Técnica Aeroespacial; Ministry of Science and Innovation’s Centre for the Development of Industrial Technology; Spanish State Research Agency (AEI) Project MDM-2017-0737 Unidad de Excelencia “María de Maeztu”—Centro de Astrobiología; Grupos Gobierno Vasco IT1366- 19; and European Research Council Consolidator Grant no 818602. The US co-authors performed their work under sponsorship from NASA’s Mars 2020 project, from the Game Changing Development programme within the Space Technology Mission Directorate and from the Human Exploration and Operations Directorate. Part of this research was carried out at the Jet Propulsion Laboratory, California Institute of Technology, under a contract with the National Aeronautics and Space Administration (80NM0018D0004). G.M. acknowledges JPL funding from USRA Contract Number 1638782. A.G.F. is supported by the European Research Council, Consolidator Grant no. 818602.Peer ReviewedPostprint (published version

Revontulialimyrskyjen havainnot vuodesta 1914: leveyspiirijakauma ja energetiikka

The Earth is in a constant interaction with the solar wind. This interaction varies over different time scales, depending on the conditions of the Sun and the near-Earth space. The solar wind energy convection and dissipation in the Earth’s magnetosphere and ionosphere give rise to disturbances in the geomagnetic field, collectively called geomagnetic activity. Auroral substorm, a common phenomenon in the northern and southern auroral region, is one of the main forms of geomagnetic activity. Understanding the substorm variability over time and at different locations improves the capability to predict the activity and prepare for it. This master's thesis examined the long-term and seasonal substorm variation and latitudinal distribution in the northern auroral region, with the focus on the ionospheric energy dissipation. Substorms were identified with an automated search algorithm from ground-based magnetometer measurements in Fennoscandia and Svalbard. The latitudinal analysis covered years 1993-2018, and the centennial activity at Sodankylä was examined during 1914-2015. The interannual and annual substorm trends were found to vary over the latitude range, with the largest overall energy dissipation observed at the Sørøya station (70.5N) and the most frequent substorm activity at the Bear Island station (74.5N). The longest substorms, on average, were observed at Kevo (69.7N) and the strongest at Sodankylä (67.4N) and Muonio (68.0N). In the centennial analysis of the Sodankylä observations, substorms were found to occur most frequently during the declining phase of the solar cycles. It was concluded that the observation latitude may make a significant difference in ground-based substorm research, and thus sufficient latitudinal coverage should be considered.Maapallo on jatkuvassa vuorovaikutuksessa aurinkotuulen kanssa. Tämä vuorovaikutus vaihtelee eri aikaskaaloilla riippuen Auringon ja Maan lähiavaruuden olosuhteista. Aurinkotuulen syöttämän energian kierto ja dissipaatio Maan magnetosfäärissä ja ionosfäärissä saa aikaan magneettikentän häiriöitä eli geomagneettista aktiivisuutta. Revontulialimyrsky on yksi geomagneettisen aktiivisuuden pääasiallisimmista ilmentymistä ja yleinen ilmiö sekä pohjoisella että eteläisellä revontulialueella. Tutkimalla alimyrskyjen aikavaihtelua sekä esiintymispaikkoja parannamme kykyämme ennustaa ja varautua niihin. Tässä diplomityössä tarkasteltiin alimyrkyjen pitkäaikais- ja vuodenaikaisvaihtelua sekä leveyspiirijakaumaa pohjoisella revontulialueella, huomioiden erityisesti energian dissipaatio ionosfäärissä. Alimyrskyt identifioitiin automaattisella hakualgoritmillä maanpinnalla tehdyistä magnetometrimittauksista Fennoskandiassa ja Huippuvuorilla. Leveyspiirianalyysi käsitti vuodet 1993-2018, ja lisäksi tutkittiin Sodankylän aseman aktiivisuutta yli sadan vuoden jaksolla 1914-2015. Pitkäaikaisten ja vuosittaisten alimyrskytrendien todettiin vaihtelevan leveyspiirien mukaan. Kaiken kaikkiaan eniten energiaa arvioitiin dissipoituvan Sørøyan magnetometriasemalla (70.5N), kun taas eniten revontulialimyrskyjä havaittiin Karhusaaren asemalla (74.5N). Keskimäärin pitkäkestoisimmat alimyrskyt havaittiin sen sijaan Kevossa (69.7N) ja voimakkaimmat Sodankylän (67.4N) sekä Muonion (68.0N) alueella. Sodankylän satavuotisia mittauksia tutkittaessa huomattiin, että eniten alimyrskyjä esiintyi aurinkosyklien laskevan vaiheen aikana. Tulosten perusteella pääteltiin, että havaintoleveyspiirillä voi olla huomattava merkitys alimyrskyjen tutkimuksessa, ja riittävä leveyspiirien kattavuus tulisi siksi huomioida

MEDA HS : Relative humidity sensor for the Mars 2020 Perseverance rover

The Finnish Meteorological Institute (FMI) provides a relative humidity measurement sensor (HS) for NASA’s Mars 2020 rover. The sensor is a part of the Mars Environmental Dynamic Analyzer (MEDA), a suite of environmental sensors provided by Spain’s Centro de Astrobiolog´ıa. The main scientific goal of the humidity sensor is to measure the relative humidity of the Martian atmosphere near the surface and to complement previous Mars mission atmospheric measurements for a better understanding of Martian atmospheric conditions and the hydrological cycle. Relative humidity has been measured from the surface of Mars previously by Phoenix and Curiosity. Compared to the relative humidity sensor on board Curiosity, the MEDA HS is based on a new version of the polymeric capacitive humidity sensor heads developed by Vaisala. Calibration of humidity devices for Mars conditions is challenging and new methods have been developed for MEDA HS. Calibration and test campaigns have been performed at the FMI, at University of Michigan and the German Aerospace Center (DLR) in Berlin to achieve the best possible calibration. The accuracy of HS and uncertainty of the calibration has been also analysed in detail with VTT Technical Research Centre of Finland. Assessment of sensor performance after landing on Mars confirms that the calibration has been successful, and the HS is delivering high quality data for the science community

Water vapor at Jezero Crater, Mars

International audienceWater on Mars is of interest today to assess the current cycling of water in and out of the regolith, cycling of water on and off of the polar caps, and to understand the current habitability potential of Mars. The regolith at polar and non-polar latitudes is an important reservoir for water storage, and an important resource for human exploration, and exchange of water between the regolith and atmosphere may play an important role in the global water cycle. Understanding water on Mars today helps us model the water cycle during different epochs on Mars, during which there was much more liquid water present in the system and Mars may have been inhabited.Additional time coverage and an additional location on the surface of Mars provided by the Perseverance MEDA relative humidity measurements at Jezero crater help reveal the regional similarities and differences across Mars. In addition, the Perseverance SuperCam or TIRS instruments can be used with the MEDA measurements of relative humidity to detect frost formation [2], to assess diurnal changes in the near-surface water content, possibly due to subsurface exchange (e.g., [5-6, 1]) or consistent with surface frost [2], and to check whether the environmental conditions at the surface and in the near surface are compatible with the formation of liquid brines [3-4].We examine the water vapor in the Martian atmosphere in the vicinity of Jezero Crater, Mars, where the Perseverance Rover is currently operating and acquiring data. We place the new water measurements from the rover instruments into the broader context, relating measurements to those of orbiters and other landers

Water vapor at Jezero Crater, Mars

International audienceWater on Mars is of interest today to assess the current cycling of water in and out of the regolith, cycling of water on and off of the polar caps, and to understand the current habitability potential of Mars. The regolith at polar and non-polar latitudes is an important reservoir for water storage, and an important resource for human exploration, and exchange of water between the regolith and atmosphere may play an important role in the global water cycle. Understanding water on Mars today helps us model the water cycle during different epochs on Mars, during which there was much more liquid water present in the system and Mars may have been inhabited.Additional time coverage and an additional location on the surface of Mars provided by the Perseverance MEDA relative humidity measurements at Jezero crater help reveal the regional similarities and differences across Mars. In addition, the Perseverance SuperCam or TIRS instruments can be used with the MEDA measurements of relative humidity to detect frost formation [2], to assess diurnal changes in the near-surface water content, possibly due to subsurface exchange (e.g., [5-6, 1]) or consistent with surface frost [2], and to check whether the environmental conditions at the surface and in the near surface are compatible with the formation of liquid brines [3-4].We examine the water vapor in the Martian atmosphere in the vicinity of Jezero Crater, Mars, where the Perseverance Rover is currently operating and acquiring data. We place the new water measurements from the rover instruments into the broader context, relating measurements to those of orbiters and other landers

Observations of the climate near the surface of Jezero over a half Mars year

International audiencePerseverance landed on Jezero with the most complete suite of environmental sensors ever sent to the surface of another planet. It combines the Mars Environmental Dynamics Analyzer (MEDA), the MastCam-Z and Engineering cameras, SuperCam spectrometers and, finally, the several microphones onboard the Mars 2020 rover. The most recent collection of atmospheric observations at Jezero and their interpretation are building an understanding of what physical processes drive the behavior of the Martian atmosphere near the surface of Jezero. We report on the observed Martian cycles of pressure, temperature, dust opacity with their physical aerosol properties, and the hydrological cycle at Jezero. These cycles have shown different behaviors on time scales from diurnal to seasonal and annual to other locations where we landed before. The differences illustrate the range of environmental processes that one can find near the red planet’s surface. We also report on the observed evolution of the near-surface boundary layer thermodynamics during the day and nighttime regimes