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The Mars Microphone onboard Supercam for the Mars 2020 rover
(1) Universite de Toulouse, ISAE-Supaero, DEOS/SSPA, Toulouse, France ([email protected]),
(2) IRAP, CNRS, Universite Paul Sabatier, Toulouse, France, (3) LANL, Los Alamos, NM (4) APL
David Mimoun1, Sylvestre Maurice2, Anthony Sournac1, Alexandre Cadu1, Marti Bassas 1, Murdoch Naomi1, Baptiste Chide1, JérémieLasue2, Ralph Lorenz4, Roger Wiens3 and the SuperCam team
A Short History of PlanetaryMicrophones (1/3)
n The short history of the planetary microphones began probably with Grozo2 instrument during the Venera 13 and 14 mission
n First Planetary microphone on Huygensn Successfully retrieved the descent sounds
n
2 June 2011 - 2
(http://mentallandscape.com/V_Venera11.htm)
A Short History of PlanetaryMicrophones (2/3)
n Second opportunity on Mars Polar Landern Mars Microphone Development up to FM
by Greg Delory (UC Berkeley)n Support by the Planetary Societyn Failed landing of MPL
n Third opportunity with Phoenix : soundcoupled with Mardi imager (Not used)
3 June 2011 - 3
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DREAMS Date: 01 03 2011
Pag.: 45/187 ExoMars EDM Science AO 5.2 Accommodation Envelope Taking into account both the sensor and the lander requirements, two possible accommodations are studied and shown in the Figure 19 and Figure 20. For exact dimensions, details, MICD and additional views, please refer to Annex #4.
MicroMETSIS
VISTACamera Cal. Traget
Microphone Sensor
MicroAres
MicroMIMA
MicroMED
Microphone Sensor Elect.
MEtBaro
Camera System
MarsTemMarsWind
CEU
LanderBattery
MicroMETSIS
VISTACamera Cal. Traget
Microphone Sensor
MicroAres
MicroMIMA
MicroMED
Microphone Sensor Elect.
MEtBaro
Camera System
MarsTemMarsWind
CEU
LanderBattery
Camera FoV55°x83°
MicroMIMAFoV 130°
Camera FoV55°x83°
MicroMIMAFoV 130°
Figure 19: DREAMS accommodation #1, CEU and Battery in place of CTPU position.
MicroMETSIS
VISTA
Camera Cal. Traget
MicrophoneSensor
MicroAres
MicroMIMA
MicroMED
Microphone Sensor Elect.
MEtBaro
Camera System
MarsTem MarsWind
CEU
LanderBattery
MicroMETSIS
VISTA
Camera Cal. Traget
MicrophoneSensor
MicroAres
MicroMIMA
MicroMED
Microphone Sensor Elect.
MEtBaro
Camera System
MarsTem MarsWind
CEU
LanderBattery
Camera FoV55°x83° MicroMIMA
FoV 130°
Camera FoV55°x83° MicroMIMA
FoV 130°
Figure 20: DREAMS accommodation #2, CEU and Battery in place of UHF Electronics position.
5.2.1 External unit requirements
Camera system is the sensor imposing the strongest accommodation constraints. MARIE Camera system: Below is the list of specifications relevant to identify MARIE requirements:
1. Focus from 500 mm up to infinite 2. FoV: 55°x83° (100° diagonal) 3. Calibration target to be positioned nominally within focus range (>390-400 mm).
After landing, EDM platform may be tilted up to +/- 40° and centre of the EDM baseplate may lie between 0.25 m and 0.60 m above nominal Martian surface (respectively for a horizontal and a 40° tilted attitude). Considering the above constraints, the following requirements for the camera accommodation have been considered: a) Calibration target shall stay at a minimum distance of 400 mm;
Schiaparelli, w/o heat shield & back cover
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The Mars Microphone sensor was considered a low-risk development, but was judged by the Science panel to lack sufficient scientific justification
A Short History of PlanetaryMicrophones (3/3)
Acoustics on Mars is complicated
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Very strong absorptionWilliams (2001)
102 103 104 105
Frequency (Hz)
0
10
20
30
40
50
60
Soun
d in
tens
ity (d
B)
Sound amplitude as a function of the distance for noise source = 60 dB4 m7 m10 m
Sound amplitude vs. distance on Mars
Increasing distance
Microphone science goals have to be crystal clear
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SuperCam on Mars 2020
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SuperCam is used to study Rocks at distance
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SuperCam is used to study Rocks at distance
Dr. Steven J. Rehse / What is LIBS?
+ soundSpectrum
SuperCam on Mars 2020
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SuperCam is used to study Rocks at distance
Dr. Steven J. Rehse / What is LIBS?
+ soundSpectrum
The science objectives of the Mars Microphone are: 1) To support the LIBS investigation to obtain unique properties of Mars
rocks and soils through their coupling with the LIBS laser.2) To contribute to basic atmospheric science: wind, convective vortices, dust
devils studies at close distance or when interacting with the rover.3) To monitor various artificial sounds.
Microphone science goals
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Microphone will record LIBS impacts up to 4 metersRovers Sounds
1 atm, Air
7.5 mbars, CO2
Freq (Hz) 104102
Pa/√
Hz
4 m
Microphone accommodation
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Mast unit (Interior view)RWEB (External view)
RWEB (External view)
FEE + Cover
Post + Microphone
MTB3-B
MIC + PT1000
MIC-FEE
SuperCam EQM Model
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What can we learn from LIBS acoustics?
The intensity of the acoustic signal acquired as thepeak-to-peak amplitude of acoustic waveformisproportional to the ablated masses (Chaléard et al.,1997; Grad and Mozina 1993)
The mass ablated is obtained from the acoustic signalamplitude.
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velocity of acoustic wave
front
distanceablated mass
peak-to-peak amplitude of acoustic waveform (pressure
gap)
5.2. Waveforms of JSC-1 targets281
The acoustic waveforms for laser impacts onto the compacted JSC1 targets are presented in282
Fig. 15. Although the shape of the waveform is similar to the waveforms produced by impacts283
onto the Aluminium target (see Fig. 6) the peak amplitude is 11.7 ⇥ 10�3 Pa lower for JSC1284
samples than for Aluminium target.285
Figure 15 shows that the peak acoustic amplitude increases with target compaction up to a286
level of compaction of 6 tonnes. For the higher levels, the amplitude remains constant. This287
behaviour follows the variation of the Vickers Hardness indicating that the Vickers Hardness is288
a critical parameter influencing the acoustic signal.289
0 0.2 0.4 0.6 0.8 1 1.2Time (ms)
-0.01
-0.005
0
0.005
0.01
0.015
Pres
sure
(Pa) 2 t
3 t4 t6 t8 t10 t15 t
Figure 15: Waveforms of JSC1 targets at di↵erent levels of compaction as measured by the microphone at 1.5 m fromthe targets. Each line represents the average signal over 10 shots around the 300th shot of the acquisition.
5.3. Analysis of the target craters290
The resulting JSC-1 impact craters were analyzed with a microscope (Olympus GX 71, mag-291
nification factor x100) and the pictures are represented in Fig. 16. The average dimension of292
the crater in the direction of the laser beam is 828 ± 23 µm. There is no significant change in293
resulting crater diameter with the target compaction (< 3 %). Unfortunately, the 45� laser impact294
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The sound peak amplitude increases with the hardnessof the material
Waveforms of JSC1 targets at different levels ofcompaction as measured by the microphone at 1.5 mfrom the targets.
The LIBS acoustic signal constraints the material hardness
(Murdoch et al, 2018, submitted)
Bandwidth of acoustic signals on Mars
n Frequency ranges of the different signals to be calibrated
Aeroacoustics (1 Hz to 500 Hz) for wind speeds < 20 m/s, object sizes > 1 cm
Vortices (10 Hz to 1 kHz) for vortex diameters 1 – 30 m
Dynamic pressure (all frequencies) but drops off rapidly with increasing frequency
Rover activities (1-10 kHz)
Saltation(5-10 kHz)
LIBS acoustics (0.5-5 kHz)
FREQUENCY (Hz)
104103102101100
MICROPHONE BANDWIDTH (100 Hz – 10 kHz)
Nelke and Vary, 2014
Microphone Radiation issues
n Microphone gain had decreased sharply after X-ray inspectionsn All other operations (Shocks, Serialization, retinning) have no impact on
performancen All flight/qualification microphones have been exposed to X-ray
n Need of another lot
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Blue curves (light and dark): no X-ray inspectionOther curves: X-ray inspection
Calibration: End to end
Objectives: n Verify the gains of the instrument in the windy
Martian environmentn Ensure microphone is not saturated by Aeolian
noise
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Test details:n Use of AWTSII 2010 Martian
wind tunnel foreseen (2m x 2m x 0.9m) in Denmark
n LIBS-like sound + MIC operation + Martian atmosphere over a sufficient distance, with wind.
n Target: Spring 2017Arhus wind tunnel, Denmark
Aarhus end-to-end validation tests
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To summarize
n There will be a microphone on Mars 2020 (FM delivered in february 2018, Supercam FM this fall)
n You can hear sounds on Mars (even if it’s tough)n You can do science with it !
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Arm
Wheels
MOXIE
Helicopter+ other engineering noise
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Thanks to : CNESISAE-SUPAEROIRAPLANLJPL