Schumann Resonance from Earth to Titan Dana Ionita School of Earth & Atmospheric Sciences Georgia Institute of Technology

Outline Definition Earth cavity dimensions & properties Titan (properties) Huygens probe (observations) cavity dimensions & properties (a bit more complex) energy source: ??? possibilities liquid ocean Conclusion: 2 big questions about Titan

Schumann waves Resonance waves of the atmospheric cavity formed between the Earth’s surface and ionosphere, two conductive surfaces with a non-conductive atmosphere Simoes et al. (2007)

Earth Dimensions & properties Surface conductivity (  ) = 0.01 (land) and 1 (sea) S m -1 Frequencies (obs) = 7.8, 14, 20, 26, 33, 39, 45 Hz (+/- 0.5 Hz daily) Cavity height (h) = 100 km Radius (R p ) = 6378 km Skin depth (d) = 0 km Energy source: lightning Siingh et al. (2006)

Titan Cavity properties Ionosphere at 1,200 km, 63 km h (  ~ S m -1 ) = 750 km Surface conductivity (  ) = S m -1 Radius (R p ) = 2575 km Skin depth (d) = 100 km Simoes et al. (2008)

Frequencies on Titan Huygens (Jan 14, 2005) observed: 36 Hz ELF wave Instrumentation noise most likely ruled out as source Model results: (19.15), (34.32), (49.48) Hz Beghin et al (2007)

Energy source ??? Lightning not observed, but not ruled out Titan ionosphere & motion of Saturn’s magnetosphere Blanc et al (2002)

Titan’s liquid ocean Titan is believed to have an underground liquid water layer Modeling of Titan cavity  shape & size of cavity  depth of underground liquid water surface Sotin & Tobie (2008)

Further Work 2 questions about Schumann resonance at Titan: Energy source - faint lightning possible, not observed - interactions with Saturn’s magnetosphere need to be better understood Depth of liquid ocean - the cavity properties can be relatively well constrained in a model

Thank you. Any Questions?