Laser-induced breakdown spectroscopy acoustic testing of the Mars 2020 microphone

Abstract

The SuperCam instrument suite onboard the Mars 2020 rover will include the Mars Microphone, an experiment designed to record the sounds of the SuperCam laser strikes on rocks and also aeolian noise. In order to record shock waves produced by the laser blasts, the Mars Microphone must be able to record audio signals from 100 Hz to 10 kHz on the surface of Mars, with a sensitivity sufficient to monitor a laser impact at distances up to 4 m. The Aarhus planetary simulator facility has been used to test the Mars 2020 rover microphone in a controlled Martian environment. The end-to-end tests performed in a 6 mbar CO 2 atmosphere, with wind, and also with the microphone at À80 C have demonstrated that the SuperCam/Mars Microphone requirements are satisfied. Tests were also performed on Martian soil simulant targets showing that the variation of the acoustic energy of the shock wave depends on the level of compaction of the target.

Listening to laser sparks: a link between Laser-Induced Breakdown Spectroscopy, acoustic measurements and crater morphology

“…The results of this section confirm the trend observed acoustically in Murdoch et al [8] and noted spectrally for gypsum and other targets in Wiens et al [23], and extends it over a larger range of densities/ hardnesses and samples. In the former acoustic study, this behavior is attributed to different rates of growth of the LIBS craters.…”

“…The measurements were averaged over a series of 500 shots, but none of the following were analyzed: the shot-to-shot variations of the volume, the shot-to-shot variations of the acoustic signal and the shot-to-shot variations of emission lines' intensity. More recently, as part of the Mars Microphone test campaign, Murdoch et al [8] characterized the behavior of the LIBS acoustic signal as a function of the number of laser shots in the same crater under a simulated Martian atmosphere at two different plasma-to-microphone distances. Although the decrease of the acoustic energy was attributed to the growth of the crater, its evolution was not monitored.…”

Shock Waves in Laser-Induced Plasmas

“…After more than 30 years the idea of using the acoustic wave intensity as a measure of the ablated mass was revived by Murdoch et al [41] and Chide et al [42], with the aim of improving the performances of the SuperCam LIBS instrument which is supposed to be delivered to Mars in 2020 [43].…”

Pulsed laser-induced heating of mineral phases: Implications for laser-induced breakdown spectroscopy combined with Raman spectroscopy

“…(2) A timeresolved (TR) Raman and luminescence spectrometer with a substantially larger analytical footprint than LIBS and (3) a visible and infrared (VISIR) spectrometer [16], also with a larger footprint than the LIBS, will together give mineralogical information complementing the chemical information provided by LIBS. In addition, SuperCam will include (4) a microphone [17] and (5) a high-resolution color imager [18] for context imagery. The Mars 2020 mission is also equipped with a deep UV Raman instrument called Scanning Habitable Environments with Raman & Luminescence for Organics & Chemicals (SHERLOC) and a Xray fluorescence instrument called Planetary Instrument for X-ray Lithochemistry (PIXL) which have analytical footprints smaller or in the range of the LIBS crater and are made for analyses at fine spatial scales for proximity science.…”