Newly formed craters on Mars located using seismic and acoustic wave data from InSight

Abstract

Meteoroid impacts shape planetary surfaces by forming new craters and alter atmospheric composition. During atmospheric entry and impact on the ground, meteoroids excite transient acoustic and seismic waves. However, new crater formation and the associated impact-induced mechanical waves have yet to be observed jointly beyond Earth. Here we report observations of seismic and acoustic waves from the NASA InSight lander's seismometer that we link to four meteoroid impact events on Mars observed in spacecraft imagery. We analyzed arrival times and polarization of seismic and acoustic waves to estimate impact locations, which were subsequently confirmed by orbital imaging of the associated craters. Crater dimensions and estimates of meteoroid trajectories are consistent with waveform modeling of the recorded seismograms. With identified seismic sources, the seismic waves can be used to constrain the structure of the Martian interior, corroborating previous crustal structure models, and constrain scaling relationships between the distance and amplitude of impact-generated seismic waves on Mars, supporting a link between the seismic moment of impacts and the vertical impactor momentum. Our findings demonstrate the capability of planetary seismology to identify impact-generated seismic sources and constrain both impact processes and planetary interiors.

Largest recent impact craters on Mars: Orbital imaging and surface seismic co-investigation

“…3D). Above the cutoff frequency, the amplitude shows a cubed frequency drop-off, as also observed for closer, smaller impacts on Mars ( 8 ) and for shallow explosions on Earth ( 26 , 27 ).…”

“…On Earth, a multitude of seismic events with known source locations, for example, explosion sources, have been used extensively for evaluating seismic velocity models, even down to the Earth’s core ( 7 ). In contrast, there have been only a few confirmed seismic source locations on Mars (all impacts), but these were small (<12 m in diameter) and near InSight (<300 km away), so the seismic paths only sampled the shallow crust ( 8 ). The two newly formed impact craters reported here allow for an evaluation of deep interior Mars global velocity models and observations of the dynamics of the hypervelocity impact process.…”

Surface waves and crustal structure on Mars

“…S2). As for the R1 observation, the time of this arrival was far outside the time window for a potential direct or ground-coupled infrasound wave originating from the impact source region ( 20 , 23 ). However, the timing was consistent with that expected for the major-arc Rayleigh wave (R2) that propagated in the opposite direction around Mars.…”

The Seismicity of Mars Observed by the NASA InSight Mission

“…For four VF seismic events closer than 300 km, dispersive acoustic signals propagating along an acoustic waveguide were detected in the form of dispersive chirps with strong elliptical polarization pointing toward the impact source (Garcia et al . 2022). This allowed us to qualify the events as impacts and to locate them using differential times between seismic P and S and acoustic waves and atmospheric models.…”

“…CTX and HiRISE images confirmed fresh craters in the error ellipses of the locations (Garcia et al . 2022). Investigations are being conducted to understand if other VF events can be confirmed as impacts.…”