Assistant Research Professor
The primary objective of this study is to determine the magnitude of the seismic contribution of naturally occurring, meteoritic impacts to the current seismicity of Mars. Recent images of the Martian surface have revealed that fresh impacts occur on a regular basis even over the relatively short time scales of orbital spacecraft missions. Such impacts provide a constant background of planet-wide seismicity, and add a substantial number of seismic sources to an otherwise assumed seismically quiet planet, with a natural quake rate estimated to be ~1000 times lower than on Earth. A secondary objective of this study will therefore be to evaluate the potential of meteoritic impact seismic signals as a source for exploration of the Martian interior. This is a potentially rich and relatively unexplored source of seismic activity that may be used to answer fundamental questions about the planet's internal structure, such as the size and nature of the core, the composition and layering of the mantle, and the planet's crustal thickness and variability.
To fulfill these objectives, this multidisciplinary investigation will combine laboratory experiments and numerical modeling to:
1. Characterize, in detail, the transfer of kinetic energy from an impacting object to seismic waves.
2. Determine the planet's surface-impulse seismic response for a range of Martian interior models that include realistic layering, attenuation, and heterogeneity assumptions.
3. Combine (1) and (2) with a modern model of the Martian impactor space-time-size distribution to estimate the amplitude and frequency of impact-induced seismicity over the planet's surface during one Martian year, and evaluate its potential for exploration of the planet's interior.
In accordance with the Mars Fundamental Research Program goals, this proposed work will directly improve our understanding of Mars relative to current knowledge, and will contribute to our "understanding of the seismic state of the planet" (MEPAG 2008 report, Goal III, Objective B, Investigation 1). In addition, the potential exploitation of this under-explored seismic signal source for fundamental research of the Martian interior addresses the goals of the MEP Robotic Mars Exploration Strategy 2007-2016 (2006), by supporting a future geophysical / seismic network on the surface of Mars.