Extended Data Fig. 3: Comparison between discharge and laser-induced acoustic signal.
From: Detection of triboelectric discharges during dust events on Mars
Solid blue and red spectra represent the acoustic signal of discharges recorded on Sol 317 and Sol 1,296, respectively. Red spectrum is offset by a factor of 2 for display. The dotted blue spectrum corresponds to the noise floor of the instrument. They are compared with the average spectrum of SuperCam laser-induced acoustic signals (grey curve, offset by a factor 100) recorded for targets ablated at 3 m from the instrument (blast of approximately 0.5 Pa amplitude, comparable with the sound amplitude of the Sol 1,296 discharge). The two discharges are recorded at a sampling frequency of 25 kHz, whereas the laser-induced acoustic signal is recorded at a sampling frequency of 100 kHz (Methods section ‘Microphone data collection’). The similar lobed shape spectra indicate that the acoustic source is of the same nature, that is, a shock wave. Laser-induced acoustic spectrum and discharge spectra show the spectral notch around 6 kHz, indicative of the echo on the SuperCam housing.
