Home / Node / Mark Panning Colloquium Abstract (Apr 25, 2018)

Mark Panning Colloquium Abstract (Apr 25, 2018)

Extraterrestrial Seismology: What We Can Learn on Mars and Icy Ocean Worlds

The InSight mission is planned to launch in May of this year, and will hopefully be returning seismic and other geophysical data from Mars by the end of 2018.  Meanwhile, mission concepts that include seismometers landing on the icy ocean worlds of Europa and Titan are in active development, while the planetary science decadal survey has prioritized a possible new geophysical network on the Earth's moon.  Seismology on other planetary bodies may be entering a new golden age after a long stretch with no new data since the 1970's. Seismology on other planets presents a different set of challenges than it does on Earth and this talk will talk about some of those challenges for Mars and icy ocean worlds, but it is critical in order to advance our knowledges of the interiors of bodies beyond Earth to help us understand how planets form and evolve in our solar system and beyond.

Technical Talk: Improved Estimations of Seismic Signal and Noise Amplitude on Tidally Driven Icy Ocean Worlds

In order to define what seismic measurements need to be made on icy ocean worlds like Europa and Titan, we need to estimate event recurrence intervals, and perform wave propagation modeling in order to estimate likely seismic amplitudes observed over realistic mission timeframes.  One approach to do this would be to estimate tidal stresses and combine them with estimated ice frictional and rheological properties to estimate likely event sizes.  This approach, however, is limited by many unknown properties of the ices and thermal state of the ice shells of these bodies.  Alternatively, we can estimate based on a simple power-law Gutenberg-Richter distribution with parameters constrained and extrapolated from the record of the Earth's moon.  Using this, we can estimate likely signal levels for large events as well as background noise from nearly continuous small events, as well as make estimates of spatial and temporal variability.  For Europa, ocean motion will also likely be an important noise source, and we have made initial estimations of this, while Titan will likely also see important noise generated by the dense atmosphere and polar surface hydrocarbon lakes.