SuperCam's Microphone Records a Martian Dust Devil
Research 00:28 min

SuperCam’s Microphone Records a Martian Dust Devil

00:28 min

15 December 2022

SuperCam’s Microphone Records a Martian Dust Devil NASA

This video and audio show the results of NASA’s Perseverance Mars rover using its SuperCam microphone to record the sounds of a Martian dust devil – the first time any such recording has been made. The dust devil passed by on Sept. 27, 2021, the 215th Martian day, or sol, of the mission. The dust devil was estimated to be 82 feet (25 meters) wide, at least 387 feet (118 meters) tall, and moving at about 12 miles per hour (19 kilometers per hour).
At the same time that SuperCam’s microphone recorded the dust devil, Perseverance’s weather sensors (measuring wind, pressure, temperature, and dust) and the Navigation camera (Navcam) were on. This allowed scientists to combine sound, image, and atmospheric data. The unique combination of these data, along with atmospheric modeling, allowed the researchers to estimate the dust devil’s dimensions.
Capturing a passing dust devil takes some luck. Scientists can’t predict when they’ll pass by, so rovers like Perseverance and Curiosity routinely monitor in all directions for them. As scientists see them occur more frequently at a certain time of day, or approaching from a certain direction, they’ll focus their monitoring to try and catch a dust devil.
The video included here shows three rows. The top row is a raw image taken by Navcam of the Martian surface; while the camera is capable of color, it takes black-and-white images when searching for dust devils to reduce the amount of data sent back to Earth (most of the images come back without a dust devil detected).
The middle row shows the same image processed with change detection software to indicate where movement occurred as time passed by; color is used to show density of dust, going from blue (noise to low density dust) through purple to yellow. The last row is a graph showing a sudden drop in air pressure recorded by Perseverance’s weather sensor suite, called Mars Environmental Dynamics Analyzer, provided by Centro de Astrobiología (CAB) at the Instituto Nacional de Tecnica Aeroespacial in Madrid and the sound amplitude from SuperCam’s microphone.
Discover... ISAE-SUPAERO's “S-Visu” wind tunnel!
Companies 1:50 min

Discover... ISAE-SUPAERO’s “S-Visu” wind tunnel!

1:50 min

29 November 2022

Discover... ISAE-SUPAERO’s “S-Visu” wind tunnel! ISAE-SUPAERO / SapienSapienS

The “S-Visu” wind tunnel is the only open loop wind tunnel in the department. Unlike closed loop wind tunnels recirculating air, air is here drawn from outside, passes through the test section and is evacuated outside thanks to a downstream centrifugal suction compressor.
This wind tunnel is thus particularly suitable for flow disturbances studies: the disturbances generated in the test section are evacuated without modifying the conditions entering the wind tunnel. The test section is 45 cm wide and 3 m long. The velocity can reach 35 m/s. Without any disturbance, the geometry, and treatment of the duct (filters, honeycomb, and fine grids) guarantee good spatial and temporal homogeneity of the flow which has a turbulence rate close to 0.3%.
Here, oscillating shutters are placed downstream the test section to generate controlled quasi-sinusoidal temporal variations of the flow velocity. The pressure losses associated with the closing of the shutters can generate a sharp decrease as strong as 50% of the streamwise velocity.
Such aerological disturbances can be recorded during a low altitude flight, particularly in an urban environment, for which the presence of buildings accentuates the intensity of apparent wind fluctuations. Thus, a micro-UAV flying at 10 m/s is likely to encounter wind gust of large spatial extension and of similar amplitude to its own forward speed. The properties and effects of atmospheric turbulence on the flight performance of these light, small-sized and low-speed aircraft are therefore very different from what is conventionally known for airliners.
The challenge is to design drones, microdrones, nanodrones robust to wind gust.
In that video, the unsteady aerodynamic response of a wing subjected to a sinusoidal variation of the streamwise velocity is studied. The wing dimensions and speeds studied are representative of a microdrone flight in an urban environment.
The desired gust properties are ensured by appropriate control of the oscillating shutters. The unsteady flow is finely characterized using a hot wire probe fixed at the inlet of the test stream. The selected gust has an average speed of 10m/s with variations of +/- 4m/s over a period of 0.8 s. The overall aerodynamic performances are measured by noting the temporal evolutions of the lift, drag and pitching moment forces for different flight angles of attack.
To analyze the origin of these performances, it is necessary to properly qualify and understand the physics of the flow around the model. Particle Image Velocimetry (PIV) provides instantaneous flow velocity fields. By appropriate post-processing, the dynamics of the flow during the wind gust can be extracted.

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