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.
Rovers and landers on Mars have experienced local, regional, and planetary‐scale dust storms. However, in situ documentation of active lifting within storms has remained elusive. Over 5–11 January 2022 (LS 153°–156°), a dust storm passed over the Perseverance rover site. Peak visible optical depth was ∼2, and visibility across the crater was briefly reduced. Pressure amplitudes and temperatures responded to the storm. Winds up to 20 m s−1 rotated around the site before the wind sensor was damaged. The rover imaged 21 dust‐lifting events—gusts and dust devils—in one 25‐min period, and at least three events mobilized sediment near the rover. Rover tracks and drill cuttings were extensively modified, and debris was moved onto the rover deck. Migration of small ripples was seen, but there was no large‐scale change in undisturbed areas. This work presents an overview of observations and initial results from the study of the storm.
The pressure sensors on Mars rover Perseverance measure the pressure field in the Jezero crater on regular hourly basis starting in sol 15 after landing. The present study extends up to sol 460 encompassing the range of solar longitudes from Ls ∼ 13°–241° (Martian Year (MY) 36). The data show the changing daily pressure cycle, the sol‐to‐sol seasonal evolution of the mean pressure field driven by the CO2 sublimation and deposition cycle at the poles, the characterization of up to six components of the atmospheric tides and their relationship to dust content in the atmosphere. They also show the presence of wave disturbances with periods 2–5 sols, exploring their baroclinic nature, short period oscillations (mainly at night‐time) in the range 8–24 min that we interpret as internal gravity waves, transient pressure drops with duration ∼1–150 s produced by vortices, and rapid turbulent fluctuations. We also analyze the effects on pressure measurements produced by a regional dust storm over Jezero at Ls ∼ 155°.
Daytime convective vortices are common on Mars and Earth (Balme & Greeley, 2006). They constitute one of the various phenomena that develop in the Planetary Boundary Layer (PBL) of both planets, but are much more common and can be an order of magnitude larger on Mars due to the more extended PBL depth (Balme & Greeley, 2006). Dusty convective vortices, or dust devils (DDs), are vortices that have raised dust from the
The Mars Environmental Dynamics Analyzer (MEDA) on board Perseverance includes first-of-its-kind sensors measuring the incident and reflected solar flux, the downwelling atmospheric IR flux, and the upwelling IR flux emitted by the surface. We use these measurements for the first 350 sols of the Mars 2020 mission (L s ∼ 6°-174° in Martian Year 36) to determine the surface radiative budget on Mars and to calculate the broadband albedo (0.3-3 μm) as a function of the illumination and viewing geometry. Together with MEDA measurements of ground temperature, we calculate the thermal inertia for homogeneous terrains without the need for numerical thermal models. We found that (a) the observed downwelling atmospheric IR flux is significantly lower than the model predictions. This is likely caused by the strong diurnal variation in aerosol opacity measured by MEDA, which is not accounted for by numerical models. (b) The albedo presents a marked non-Lambertian behavior, with lowest values near noon and highest values corresponding to low phase angles (i.e., Sun behind the observer). (c) Thermal inertia values ranged between 180 (sand dune) and 605 (bedrock-dominated material) SI units. (d) Averages of albedo and thermal inertia (spatial resolution of ∼3-4 m 2 ) along Perseverance's traverse are in very good agreement with collocated retrievals of thermal inertia from Thermal Emission Imaging System (spatial resolution of 100 m per pixel) and of bolometric albedo in the 0.25-2.9 μm range from (spatial resolution of ∼300 km 2 ). The results presented here are important to validate model predictions and provide ground-truth to orbital measurements. Plain Language SummaryWe analyzed first-of-its-kind measurements from the weather station on board NASA's Perseverance rover. These include the incident solar radiation and the amount that is reflected by the surface, as well as the thermal atmospheric forcing (greenhouse effect) and the thermal heat released by the surface. These measurements comprise the radiant energy budget, which is fundamental to understanding Mars' weather through its impact on temperatures. From the solar measurements, we obtained the surface reflectance for a variety of illuminating and viewing geometries. We found that the thermal atmospheric forcing is weaker than expected from models, likely because of the strong diurnal variation in atmospheric aerosols observed by the rover, which is not accounted for by models. We also found that the surface reflectance is not uniform from all directions, but that it decreases when the Sun is highest in the sky (near noon) and increases when the Sun is directly behind the observer (sunset and sunrise), and thus the shadows cast by their roughness elements (e.g., pores and pits) are minimized. Because models neither consider diurnal variations in atmospheric aerosols nor in the surface reflectance, the results presented here are important to validate model predictions for future human exploration. MARTÍNEZ ET AL.
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