Research Pages

Overview

Global and Regional Tomography

Planetary Seismology

Theoretical Studies


The Europa work was done in collaboration with Fabio Cammarano, Vedran Lekic, Michael Manga, and Barbara Romanowicz, and the Mars work has been done in collaboration with Bruce Banerdt and the rest of the InSight Team.

InSight: a proposed Martian geophysics Discovery mission

References (click for pdf)

Panning, M.P., A. Mocquet, E. Beucler, W.B. Banerdt, P. Lognonné, L. Boschi, C. Johnson, R.C. Weber, "InSight: Using Earth data to demonstrate inversion techniques for Mars' interior" 43rd Lunar and Planetary Science Conference, Abstract #1515, 2012.
Click for pdf of poster

Banerdt, W.B., S. Smrekar, L. Alkalai, T. Hoffman, R. Warwick, K. Hurst, W. Folkner, P. Lognonné, T. Spohn, S. Asmar, D. Banfield, L. Boschi, U. Christensen, V. Dehant, D. Giardini, W. Goetz, M. Golombek, M. Grott, T. Hudson, C. Johnson, G. Kargl, N. Kobayashi, J. Maki, D. Mimoun, A. Mocquet, P. Morgan, M. Panning, W. T. Pike, J. Tromp, T. van Zoest, R. Weber, M. Wieczorek and the InSight Team, "InSight: An integrated exploration of the interior of Mars" 43rd Lunar and Planetary Science Conference, Abstract #2838, 2012.

Summary

JPL figure showing the proposed InSight lander.

InSight is one of three missions undergoing Phase A development for possible selection by NASA's Discovery Program. If selected, InSight will illuminate the fundamental processes of terrestrial planet formation and evolution by performing the first comprehensive surface-based geophysical investigation of Mars. It would provide key information on the composition and structure of an Earthlike planet that has gone through most of the evolutionary stages of the Earth up to, but not including, plate tectonics. The traces of this history are still contained in the basic parameters of the planet: the size, state and composition of the core, the composition and layering of the mantle, the thickness and layering of the crust, and the thermal flux from the interior.

A critical instrument for the InSight mission will be the Seismic Experiment for Interior Structure (SEIS). SEIS comprises two sensor assemblies deployed on the surface: a 3- axis very broad band (VBB) oblique seismometer within an evacuated sphere, and an independent 3-axis short period (SP) seismometer outside. Such instrumentation will allow for an unprecedented view of the interior of Mars. However, since the proposed mission will have only a single lander and no network, we will not be able to apply traditional source location methods and will need to take advantage of single station approaches, and these approaches should be tested with Earth data.

Long-period seismology on Europa

References (click for pdf)

Cammarano, F., V. Lekic, M. Manga, M.P. Panning, and B.A. Romanowicz, "Long-period seismology on Europa: 1. Physically consistent interior models" J. Geophys. Res., 111, E12009, doi:10.1029/2006JE002710, 2006.

Panning, M.P., V. Lekic, M. Manga, F. Cammarano, and B.A. Romanowicz, "Long-period seismology on Europa: 2. Predicted seismic response" J. Geophys. Res., 111, E12008, doi:10.1029/2006JE002712, 2006.

Summary

NASA image of Europa from Wikipedia

Europa, one of the Galilean moons of Jupiter, is of great interest to the planetary community, primarily due to evidence of an extensive liquid water ocean below the outer ice shell. Determining the thickness of that ice shell can be accomplished using seismological observations, perhaps even from orbit.

Vertical component seismograms for different ice shell thicknesses and for a model with no liquid ocean.

In order to explore the importance of long period data (periods from 10 to 1000 seconds) in constraining this and deeper structure, we first determined a range of thermodynamically self-consistent models (Paper I published in JGR Planets). These models were then used to predict the seismic response using a normal modes summation method (Paper II).

We conclude that the Rayleigh wave group velocity dispersion, which is marked by a characteristic transition to a flexural mode which depends on ice shell thickness in this frequency band, may be used to determine the ice shell thickness even if the tectonic event can not be located.