The Mars Microphone onboard Supercam for the Mars 2020 rover

David Mimoun1, Sylvestre Maurice2, Anthony Sournac1, Alexandre Cadu1, Marti Bassas 1, Murdoch Naomi1, Baptiste Chide1, Jérémie Lasue2, Ralph Lorenz4, Roger Wiens3 and the SuperCam team

(1) Université de Toulouse, ISAE-Supaero, DEOS/SSPA, Toulouse, France ([email protected]), (2) IRAP, CNRS, Université Paul Sabatier, Toulouse, France, (3) LANL, Los Alamos, NM (4) APL 1 A Short History of Planetary Microphones (1/3) n The short history of the planetary microphones began probably with Grozo 2 instrument during the Venera 13 and 14 mission

(http://mentallandscape.com/V_Venera11.htm)

n First Planetary microphone on Huygens n Successfully retrieved the descent sounds n

2 June 2011 - 2 A Short History of Planetary Microphones (2/3) n Second opportunity on Mars Polar Lander n Mars Microphone Development up to FM by Greg Delory (UC Berkeley)

n Support by the Planetary Society

n Failed landing of MPL

n Third opportunity with Phoenix : sound coupled with Mardi imager (Not used)

3 June 2011 - 3

DREAMS Date: 01 03 2011 Pag.: 45/187 ExoMars EDM Science AO

5.2 Accommodation Envelope Taking into accountA Shortboth the Historysensor and ofthe Planetarylander requirements, two possible accommodations are studied and shown inMicrophones the Figure 19 and Figure (3/3) 20. For exact dimensions, details, MICD and additional views, please refer to Annex #4. Schiaparelli, w/o heat shield & back cover

MicroAres MarsWind MarsTem Camera FoV 55°x83° Camera System MicroMED

MEtBaro

TheMicrophone Mars Microphone sensor was CEU Sensor Elect. considered a low-risk development, but was 7 judged by the Science panel to lack Lande r sufficient scientific justification Battery

MicroMIMA

Camera Cal. VISTA MicroMIMA FoV 130° Traget MicroMETSIS Microphone Sensor Figure 19: DREAMS accommodation #1, CEU and Battery in place of CTPU position.

MarsWind MarsTem 4

MicroAres Camera FoV Camera 55°x83° System MicroMIMA FoV 130°

Microphone Sensor Elect. CEU

MEtBaro

MicroMED MicroMIMA

Microphone Lande r Sensor Battery VISTA

Camera Cal. Traget

MicroMETSIS

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; Acoustics on Mars is complicated

Very strong absorption Williams (2001)

Sound amplitude as a function of the distance for noise source = 60 dB 60 4 m 7 m 10 m

50

40 Increasing distance

Sound amplitude vs. 30 distance on Mars

Sound intensity (dB) 20

10

0 102 103 104 105 Frequency (Hz)

5 Microphone science goals have to be crystal clear

6 SuperCam on Mars 2020

Dr. Steven J. Rehse / What is LIBS?

Spectrum + sound

SuperCam is used to study Rocks at distance 7 SuperCam on Mars 2020

Dr. Steven J. Rehse / What is LIBS?

Spectrum + sound

SuperCam is used to study Rocks at distance 8 Microphone science goals 1 atm, Air

4 m Pa/√ Hz Pa/√

7.5 mbars, CO2

102 Freq (Hz) 104

Rovers Sounds Microphone will record LIBS impacts up to 4 meters 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.

9 Microphone accommodation

RWEB (External view)

MTB3-B

MIC + PT1000 MIC-FEE

FEE + Cover

RWEB (External view) Mast unit (Interior view)

Post + Microphone

10 SuperCam EQM Model

11 281 5.2. Waveforms of JSC-1 targets

282 The acoustic waveforms for laser impacts onto the compacted JSC1 targets are presented in

283 Fig. 15. Although the shape of the waveform is similar to the waveforms produced by impacts

3 284 onto the Aluminium target (see Fig. 6) the peak amplitude is 11.7 10 Pa lower for JSC1 ⇥

285 samples than for Aluminium target.

286 Figure 15 shows that the peak acoustic amplitude increases with target compaction up to a

287 level of compaction of 6 tonnes. For the higher levels, the amplitude remains constant. This What can we learn from288 behaviour LIBS follows acoustics? the variation of the Vickers Hardness indicating that the Vickers Hardness is 289 a critical parameter influencing the acoustic signal.

(Murdoch et al, 2018, submitted) ablated mass distance 0.015

0.01 2 t 3 t 0.005 4 t 6 t 0 8 t velocity of Pressure (Pa) 10 t peak-to-peak 15 t acoustic wave -0.005 amplitude of acoustic front waveform (pressure gap) -0.01 0 0.2 0.4 0.6 0.8 1 1.2 Time (ms) The intensity of the acoustic signal acquired as the peak-to-peak amplitude of acoustic waveform Waveforms of JSC1 targets at different levels of Figure 15: Waveforms of JSC1 targets at di↵erent levels of compaction as measured by the microphone at 1.5 m from isproportional to the ablated masses (Chaléard et al., the targets. Eachcompaction line represents theas averagemeasured signal overby 10 shotsthe aroundmicrophone the 300th shotat of1 the.5 acquisition.m 1997; Grad and Mozina 1993) from the targets. The mass ablated is obtained from the acoustic signal The sound peak amplitude increases with the hardness amplitude. 290 5.3. Analysis of the target craters of the material

291 The resulting JSC-1 impact craters were analyzed with a microscope (Olympus GX 71, mag- The LIBS acoustic signal constraints292 nification factor x100)the and the material pictures are representedhardness in Fig. 16. The average dimension of 293 the crater in the direction of the laser beam is 828 23 µm. There is no significant change in ±

294 resulting crater diameter with the target compaction (< 3 %). Unfortunately, the 45 laser impact 12 18 Bandwidth of acoustic signals on Mars n Frequency ranges of the different signals to be calibrated

MICROPHONE BANDWIDTH (100 Hz – 10 kHz)

LIBS acoustics (0.5-5 kHz)

Nelke and Vary, 2014 Rover activities (1-10 kHz)

Vortices (10 Hz to 1 kHz) for vortex diameters 1 – 30 m

Aeroacoustics (1 Hz to 500 Hz) for wind speeds < 20 m/s, object sizes > 1 cm Saltation (5-10 kHz) Dynamic pressure (all frequencies) but drops off rapidly with increasing frequency

100 101 102 103 104

FREQUENCY (Hz) Microphone Radiation issues

n Microphone gain had decreased sharply after X-ray inspections

n All other operations (Shocks, Serialization, retinning) have no impact on performance

n All flight/qualification microphones have been exposed to X-ray

n Need of another lot

Blue curves (light and dark): no X-ray inspection Other curves: X-ray inspection

14 Calibration: End to end

Objectives: n Verify the gains of the instrument in the windy Martian environment n Ensure microphone is not saturated by Aeolian noise

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. Arhus wind tunnel, Denmark n Target: Spring 2017

15 Aarhus end-to-end validation tests

16 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 !

Arm

MOXIE

Wheels

+ other engineering noise Helicopter

17 Thanks to : CNES ISAE-SUPAERO IRAP LANL JPL

18