Convective vortices and dust devils at the MSL landing site: Annual variability

The InSight (Interior Exploration using Seismic Investigations, Geodesy and Heat Transport) mission landed in western Elysium Planitia on November 26, 2018. Because of its stationary position and a multi-instrument package, InSight offers the unique opportunity of detecting changes induced by aeolian activity and constraining the atmospheric conditions responsible for particle motion.In this work, we present the most significant changes from aeolian activity as detected by the InSight lander during its first 400 Martian days of operations. We will show that particle entrainment by wind activity around InSight is a subtle process and report simultaneous measurements observed across multiple instruments. The changes observed are episodic and are seen correlated with excursions in both seismic and magnetic signals, which will be discussed further. Our observations show that all aeolian movements are consistent with the passage of deep convective vortices between noon to 3 pm local time. These vortices may be the primary initiators for aeolian transportation at InSight, inducing episodic particulate motion of grains up to 3 mm in diameter.

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Expected first results from the SuperCam microphone onboard the NASA Perseverance rover

10.5194/egusphere-egu21-8505 ◽

2021 ◽

Author(s):

Nina Lanza ◽

Baptiste Chide ◽

David Mimoun ◽

Cesar Alvarez ◽

Stanley Angel ◽

...

Keyword(s):

Acoustic Signal ◽

Analytical Techniques ◽

Landing Site ◽

Thin Layers ◽

Dust Devils ◽

Breakdown Spectroscopy ◽

Analytical Instruments ◽

Laser Induced Breakdown ◽

First Results ◽

Attenuation Models

The NASA Perseverance rover will land on Mars in February 2021, bringing with it a new suite of analytical instruments with which to explore its landing site in Jezero crater. The primary goal of this new mission is to assess the geology and past habitability in order to identify and cache samples with a high likelihood of preserving biosignatures, in preparation for a future sample return mission [1]. As part of its instrument payload, Perseverance will carry the SuperCam instrument [2-3]. SuperCam combines a number of analytical techniques, notably a laser-induced breakdown spectroscopy (LIBS) instrument for chemical analysis that is coupled with a microphone for acoustic studies. The SuperCam microphone is a commercial of-the-shelf electret (based on Knowles EK-23132) and is designed to record sounds in the audible range, from 100 Hz to 10 kHz, during the surface mission. There are three main science investigations of interest for the SuperCam microphone: 1) Analysis of the LIBS acoustic signal; 2) study of atmospheric phenomena; and 3) examination of rover mechanical sounds. Since the atmosphere will be the source of acoustic signals, the microphone may be used to better understand the nature of the atmosphere and related phenomena such as thermal gradient and convective behavior in the rover&#8217;s vicinity [4], the behavior of dust devils [5], and to refine current atmospheric attenuation models for Mars [6]. Under atmosphere, LIBS analysis produces an acoustic signal due to the creation of a shock wave during laser ablation of a target. This acoustic signal can provide critical information about a target&#8217;s hardness and ablation depth [7-8] and whether there are coatings or thin layers present [9]. Mechanisms on the rover itself will also provide a source of acoustic signal that may be examined by the SuperCam microphone, notably sounds produced by the Mars Oxygen ISRU Experiment (MOXIE, [10]) instrument pumps during oxygen production. By the time of the conference, the SuperCam microphone should have acquired the first sounds on Mars; we will report on these exciting initial results and compare them to our prelanding expectations.[1] Farley K.A. et al. (2020) SSR 216, 142. [2] Wiens R.C. et al. (2021) SSR 217(4). [3] Maurice, S. et al. (in revision) SSR. [4] Chide, B. et al. (2020) 52nd LPSC. [5] Murdoch, N. et al. (2021) 52nd LPSC. [6] Chide, B. et al. (2020) AGU Fall meeting, S007-02. [7] Chide, B. et al. (2019) SAB 153, 50-60. [8] Chide, B. et al. (2020) SAB 174, 106000. [9] Lanza, N.L. et al (2020) 51st LPSC, no. 2807. [10] Hecht, M. H. et al. (2015) 46th LPSC, no. 2774.

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Large-Eddy Simulations of Dust Devils and Convective Vortices

Space Science Reviews ◽

10.1007/s11214-016-0284-x ◽

2016 ◽

Vol 203 (1-4) ◽

pp. 245-275 ◽

Cited By ~ 13

Author(s):

Aymeric Spiga ◽

Erika Barth ◽

Zhaolin Gu ◽

Fabian Hoffmann ◽

Junshi Ito ◽

...

Keyword(s):

Large Eddy Simulations ◽

Dust Devils ◽

Large Eddy ◽

Convective Vortices

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The Michigan Prandtl System: An Instrument for Accurate Pressure Measurements in Convective Vortices

Journal of Atmospheric and Oceanic Technology ◽

10.1175/jtech-d-12-00246.1 ◽

2013 ◽

Vol 30 (10) ◽

pp. 2426-2433

Author(s):

Douglas G. Halleaux ◽

Jeffery M. Sussman ◽

Nilton O. Rennó

Keyword(s):

Wind Direction ◽

Static Pressure ◽

Average Rate ◽

Rate Of Change ◽

Intensity Change ◽

Pressure Measurements ◽

Wind Vector ◽

Dust Devils ◽

Prandtl System ◽

Convective Vortices

Abstract This article describes a Prandtl tube system developed at the University of Michigan to measure the static pressure, the total (or stagnation) pressure, and the velocity in flows whose direction and intensity change rapidly. The ever-changing wind vectors in convective vortices are a challenge for making accurate measurements on them. Accurate measurements of the static pressure are particularly problematic because they require the sensor air intake to be aligned perpendicular to the wind direction. This article describes calibrations and tests of the Michigan Prandtl System (MPS) and, in particular, the characterization of the errors in the static pressure measurements as a function of misalignments between the Prandtl tube and the wind vector. This article shows that the MPS measures the pressure with a relative error of 3.5% for wind flows whose direction is within about 10° of the MPS tube direction. It also shows that the MPS adjusts to changes in wind direction of 90° in about 1.5 s, the average rate of change expected in a typical dust devil of about 15 m of radius traveling at 10 m s−1 (Rennó et al.). Field tests indicate that misalignments between the MPS and the wind vector are usually smaller than ~30° during measurements in dust devils and that these misalignments always cause increases in the static pressure measured and decreases in the total pressure measured.

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Large-Eddy Simulations of Dust Devils and Convective Vortices

Space Sciences Series of ISSI - Dust Devils ◽

10.1007/978-94-024-1134-8_8 ◽

2017 ◽

pp. 245-275 ◽

Cited By ~ 2

Author(s):

Aymeric Spiga ◽

Erika Barth ◽

Zhaolin Gu ◽

Fabian Hoffmann ◽

Junshi Ito ◽

...

Keyword(s):

Large Eddy Simulations ◽

Dust Devils ◽

Large Eddy ◽

Convective Vortices

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On Determination of the Intensity and Size Frequency Distribution of Convective Vortices: Applications to Martian Dust Devils

10.5194/egusphere-egu2020-1738 ◽

2020 ◽

Author(s):

Michael Kurgansky

Keyword(s):

Frequency Distribution ◽

Power Law ◽

Dust Devils ◽

Size Frequency Distribution ◽

Pressure Drops ◽

Size Frequency ◽

Pressure Time ◽

Vortex Size ◽

Convective Vortices

Dust devils play a major role on Mars, providing a significant proportion of the total dust removal from the surface and its injection into the atmosphere, thus largely determining the overall radiative regime and the climatic state of the Martian atmosphere. The amount of dust lifted to the atmosphere by a population of dust devils is determined by the number density of dust devils (their number per unit area) and by their size-frequency and intensity-frequency distributions. Using the Abel transform, a two-step methodology has been developed to determine the marginal statistical distributions of convective vortices, including dust devils, on their intensity (pressure drop in the vortex center) and size (diameter), based on statistics of transient pressure drops recorded when the vortices pass near a pressure sensor placed on the surface of the planet. In a first step, if the pressure profile within the vortex is realistically modeled then the intensity-frequency distribution in the population of vortices can be inferred from the statistics of peak pressure drops recorded alone. If the observed statistics can be approximated with a truncated power-law distribution and in the absence of an apparent correlation between the vortex diameter and the maximum pressure drop at its center, then the measurements provide an unbiased power-law estimate of the actual intensity-frequency distribution. In a second step and in a practically important case when the distribution of vortices on their intensity follows the power law, the problem of determining the vortex size-frequency distribution is solved from data obtained in pressure time-series surveys. This two-step technique has been applied with success to Mars Science Laboratory (MSL) convective vortices.This work was supported by the Presidium of the Russian Academy of Sciences, project no. 19-270. The method of inferring the vortex size-frequency distribution was developed with the support from the Russian Science Foundation (grant no. 18-77-10076).References:Kurgansky M.V. On the statistical distribution of pressure drops in convective vortices: Applications to Martian dust devils // Icarus. Volume 317, 1 January 2019, Pages 209-214. https://doi.org/10.1016/j.icarus.2018.08.004.Kurgansky M.V. On determination of the size-frequency distribution of convective vortices in pressure time-series surveys on Mars // Icarus. Volume 335, 1 January 2020, 113389. https://doi.org/10.1016/j.icarus.2019.113389.

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