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We study the diurnal cycle of rapid thermal fluctuations observed by the Mars Environmental Dynamics Analyzer, onboard the Perseverance rover at Jezero Crater, as a function of local time and season. In this context, rapid refers to periods between 15 min and half a second. Some insight is also provided into wind fluctuations that are the base for most of the existing theories on turbulent flows. The results expand the observations from previous Mars missions, namely Viking, Mars Pathfinder, and Phoenix, and they add to our knowledge of near‐surface fluctuations on Mars. (a) Probability distribution functions of the fluctuations are determined and found to have exponential tails. This means that models that represent the interaction within the environment and with the surface as a stochastic forcing need to account for the sudden events responsible for the exponential tails. (b) Power density spectra are calculated and show several dynamical regimes with different slopes associated to forcing, an intermediate regime, and a higher frequency regime. All change with time of the day. The results imply that the fastest regime is not a universal scenario for the temperature fluctuations near the surface. (c) The scale dependence of the fluctuations confirms the existence of intermittent outbursts associated to the slower fluctuations, possibly associated to the larger scale structures, and explains why the spectral density slopes do not follow Kolmogorov's law. Understanding the role of larger scale structures would help refine scaling theories of the near‐surface Martian atmosphere and its interactions with the surface. Plain Language Summary: The Martian atmosphere is mostly driven by solar radiative forcing that also controls how it interacts with the surface. Atmospheric phenomena respond within seconds to years, but models can only resolve limited ranges of these time scales. This work explores how temperature fluctuates at time scales faster than what models typically resolve, and how this variability affects phenomena at the time scales that they resolve. The statistical properties of rapid environmental changes, or fluctuations, caused by solar forcing help us understand how the lowest atmosphere and surface evolve and interact. Theories that have been tested on Earth predicting how energy transfers or dissipates between the fast and slow dynamical regimes are explored here searching for rules that relate both regimes on another world. This work finds that fluctuations of air temperature and horizontal winds near the Martian surface do not follow probability distributions typical of normal random processes. The energy transfer rate is not consistent at scales faster than 10 s with a unique, or universal, rule relating fast to slow fluctuations. Finally, it suggests that this lack of universality is caused by intermittent disruptions through sudden large coherent structures, like convective vortices and waves, that influence how temperature dissipates. Key Points: Probability Distribution functions for temperature fluctuations at Jezero Crater on the time scale of seconds have exponential tailsPower density spectra of temperature fluctuations find at least two dynamical regimes that evolve differently with time of the daySudden outbursts, likely associated to coherent structures, disrupt intermittently the rate of temperature dissipation to the smaller scales [ABSTRACT FROM AUTHOR]

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 humidity at the rover's site experiences large subhour variability. Humidity observations help to understand interchange of humidity between the soil and the atmosphere. Water is mandatory for life, such as on earth, thus understanding these water cycle processes better are important for evaluating possibilities of past and current habitability of Mars. Perseverance is also collecting samples which maybe returned to Earth one day. Knowledge of the conditions at the times when samples were collected maybe useful. Key Points: Humidity observations in Mars by M2020 Perseverance rover during the first 410 sols of operation are shown and discussedHumidity sensor MEDA‐HS operations and sensor accuracy are explainedAdsorptive single column model is tested and compared with humidity observations [ABSTRACT FROM AUTHOR]

Studying the atmospheric planetary boundary layer (PBL) is crucial to understand the climate of a planet. The meteorological measurements by the instruments onboard InSight at a latitude of 4.5°N make a unique rich data set to study the active turbulent dynamics of the daytime PBL on Mars. Here we use the high-sensitivity continuous pressure, wind, and temperature measurements in the first 400 sols of InSight operations (from northern late winter to midsummer) to analyze wind gusts, convective cells, and vortices in Mars' daytime PBL. We compare InSight measurements to turbulenceresolving large-eddy simulations (LES). The daytime PBL turbulence at the InSight landing site is very active, with clearly identified signatures of convective cells and a vast population of 6,000 recorded vortex encounters, adequately represented by a power law with a 3.4 exponent. While the daily variability of vortex encounters at InSight can be explained by the statistical nature of turbulence, the seasonal variability is positively correlated with ambient wind speed, which is supported by LES. However, wind gustiness is positively correlated to surface temperature rather than ambient wind speed and sensible heat flux, confirming the radiative control of the daytime Martian PBL; and fewer convective vortices are forming in LES when the background wind is doubled. Thus, the long-term seasonal variability of vortex encounters at the InSight landing site is mainly controlled by the advection of convective vortices by ambient wind speed. Typical tracks followed by vortices forming in the LES show a similar distribution in direction and length as orbital imagery. [ABSTRACT FROM AUTHOR]

NASA's InSight landed in Elysium Planitia (~4.5°N,136°E) at Ls ~ 296° (November 2018), right after the decay of the 2018 Global Dust Storm (GDS) and before the onset of the 2019 Large Dust Storm (LDS) at Ls ~ 320° (January 2019). InSight's cameras observed a rise in the atmospheric opacities during the storm from ~0.7 to ~1.9, similarly to contemporaneous measurements by Curiosity in Gale crater. Pressure tides were strongly affected at the locations of InSight and Curiosity. In particular, the diurnal pressure mode experienced an abrupt increase during the onset of the LDS, similar to that measured by Curiosity, most likely due to longitudinally asymmetric dust loading. Later, the dust was redistributed around the planet and the semidiurnal mode evolved according to dust opacity in both missions. Before and after the onset of the storm, the observed wind patterns resulted from the interaction between regional and local slope flows induced by topography, which all produced a diurnal perturbation superimposed on a mean flow, dominated by the Hadley cell but with modifications due to channeling effects from the regional topography. However, the onset of the LDS modified this to a scenario consistent with enhanced tidal flows. The local air temperatures are strongly perturbed by the lander's thermal effects, and their retrieval significantly depends on wind patterns, which changed during the course of the dust storm. Observations suggest a decrease in convective vortices during the dust storm; however, vortex activity remained strong during the storm's onset due to the increase in wind speeds. Plain Language Summary: NASA's InSight landed in Elysium Planitia, Mars, at November 2018, right after the decay of the 2018 Global Dust Storm and before the onset of the 2019 Large Dust Storm (LDS) (January 2019). InSight's cameras observed a rise in the atmospheric opacities during the storm from ~0.7 to ~1.9, similar to contemporaneous measurements by Curiosity in Gale crater. Pressure tides were strongly affected. In particular, the amplitude of the pressure harmonics with a period of 1 sol (diurnal pressure mode) experienced an abrupt increase during the onset of the LDS, similar to that measured by Curiosity, most likely as a result of different dust loading as a function of location. Later, the dust was redistributed around the planet and the semidiurnal pressure mode evolved according to dust opacity in both missions. The onset of the storm modified the wind patterns, probably due to enhanced tidal flows. The measured air temperatures were strongly perturbed by the lander's thermal effects. The daytime lander effects significantly depend on wind patterns. Observations suggest an impact on convective vortices, with an overall decrease during the LDS. However, the vortex activity remained strong during storm onset due to the increase in wind speeds. Key Points: InSight measured the atmospheric response to a large dust storm at Ls ~ 320° in MY34Diurnal pressure amplitudes abruptly increased and vortex pressure drop decreased after an initial increase during storm onsetStorm onset strongly modified flows dominated by the Hadley circulation and local slopes to include the effect of enhanced tidal flows [ABSTRACT FROM AUTHOR]

It is now common in aerospace design to build and adapt a surrogate model to use during optimization. This process starts with a training stage based on an initial database of high-fidelity results. However, it is difficult to have a priori knowledge of the database size necessary to achieve a particular level of accuracy. Thus, many optimization processes, such as aerodynamic optimization, start with a large number of initial cases, which usually implies long computational times on high-performance computers. This article identifies and analyses key variables which influence the surrogate performance, as applied to the aerodynamic optimization of an aerofoil, such as the database size, the number of geometric design parameters, variation from the baseline geometry, Reynolds number and angle of attack. Their relationship is explored by means of sensitivity analysis and a multivariable polynomial model, and general guidelines for the selection of the most suitable database size are presented. [ABSTRACT FROM AUTHOR]

The Mars Sample Return mission intends to retrieve a sealed collection of rocks, regolith, and atmosphere sampled from Jezero Crater, Mars, by the NASA Perseverance rover mission. For all life-related research, it is necessary to evaluate water availability in the samples and on Mars. Within the first Martian year, Perseverance has acquired an estimated total mass of 355 g of rocks and regolith, and 38 μmoles of Martian atmospheric gas. Using in-situ observations acquired by the Perseverance rover, we show that the present-day environmental conditions at Jezero allow for the hydration of sulfates, chlorides, and perchlorates and the occasional formation of frost as well as a diurnal atmospheric-surface water exchange of 0.5-10 g water per m 2 (assuming a well-mixed atmosphere). At night, when the temperature drops below 190 K, the surface water activity can exceed 0.5, the lowest limit for cell reproduction. During the day, when the temperature is above the cell replication limit of 245 K, water activity is less than 0.02. The environmental conditions at the surface of Jezero Crater, where these samples were acquired, are incompatible with the cell replication limits currently known on Earth., (© 2024. The Author(s).)

Perseverance's Mastcam-Z instrument provides high-resolution stereo and multispectral images with a unique combination of spatial resolution, spatial coverage, and wavelength coverage along the rover's traverse in Jezero crater, Mars. Images reveal rocks consistent with an igneous (including volcanic and/or volcaniclastic) and/or impactite origin and limited aqueous alteration, including polygonally fractured rocks with weathered coatings; massive boulder-forming bedrock consisting of mafic silicates, ferric oxides, and/or iron-bearing alteration minerals; and coarsely layered outcrops dominated by olivine. Pyroxene dominates the iron-bearing mineralogy in the fine-grained regolith, while olivine dominates the coarse-grained regolith. Solar and atmospheric imaging observations show significant intra- and intersol variations in dust optical depth and water ice clouds, as well as unique examples of boundary layer vortex action from both natural (dust devil) and Ingenuity helicopter-induced dust lifting. High-resolution stereo imaging also provides geologic context for rover operations, other instrument observations, and sample selection, characterization, and confirmation.

Despite the importance of sand and dust to Mars geomorphology, weather, and exploration, the processes that move sand and that raise dust to maintain Mars' ubiquitous dust haze and to produce dust storms have not been well quantified in situ, with missions lacking either the necessary sensors or a sufficiently active aeolian environment. Perseverance rover's novel environmental sensors and Jezero crater's dusty environment remedy this. In Perseverance's first 216 sols, four convective vortices raised dust locally, while, on average, four passed the rover daily, over 25% of which were significantly dusty ("dust devils"). More rarely, dust lifting by nonvortex wind gusts was produced by daytime convection cells advected over the crater by strong regional daytime upslope winds, which also control aeolian surface features. One such event covered 10 times more area than the largest dust devil, suggesting that dust devils and wind gusts could raise equal amounts of dust under nonstorm conditions.

The Radiation and Dust Sensor is one of six sensors of the Mars Environmental Dynamics Analyzer onboard the Perseverance rover from the Mars 2020 NASA mission. Its primary goal is to characterize the airbone dust in the Mars atmosphere, inferring its concentration, shape and optical properties. Thanks to its geometry, the sensor will be capable of studying dust-lifting processes with a high temporal resolution and high spatial coverage. Thanks to its multiwavelength design, it will characterize the solar spectrum from Mars' surface. The present work describes the sensor design from the scientific and technical requirements, the qualification processes to demonstrate its endurance on Mars' surface, the calibration activities to demonstrate its performance, and its validation campaign in a representative Mars analog. As a result of this process, we obtained a very compact sensor, fully digital, with a mass below 1 kg and exceptional power consumption and data budget features.