[Previous] | [Session 46] | [Next]
C.D. Neish, R.D. Lorenz (Lunar and Planetary Laboratory, University of Arizona), D.P. O'Brien (Observatoire de la Cote d'Azur), Cassini RADAR Team
Observations of Titan by the Cassini spacecraft have revealed to us a world with an intricate and varied geology. In particular, there is evidence of extensive cryovolcanism. The 180 km structure Ganesa Macula observed in SAR imaging from Cassini's TA encounter in October 2004 resembles the pancake domes seen on Venus by the Magellan spacecraft and is comparable (in terms of years of planetary heatflow required to melt the lava volume) with the Deccan Traps on Earth. Cryovolcanism has important astrobiological implications, as it provides a means of exposing surface organics to liquid water. Aqueous chemistry permits Titan's hydrocarbons and nitriles to form more evolved and oxidized prebiotic species, such as amino acids and pyrimidines.
In this work, we use Titan's observed backscatter function to model the radar appearance of domes of various shapes and heights to compare with the image of Ganesa: the SAR data are better fit by a ``spreading viscous drop" (``Huppert") shape than by one constrained by a skin strength (``Nye"). We then model the freezing of the model dome using a finite-element heat conduction code. Estimation of the dome height is presently underway, but even a dome only 1 km in height takes some 5 x 103 years to freeze for lava made entirely of liquid water, and 12 x 103 years for lava made of ammonia dihydrate. These timescales open a window for prebiotic chemistry far wider than can be explored in terrestrial laboratory experiments.
This work was supported by the Cassini project.
The author(s) of this abstract have provided an email address for comments about the abstract: cdneish@lpl.arizona.edu
[Previous] | [Session 46] | [Next]
Bulletin of the American Astronomical Society, 37 #3
© 2004. The American Astronomical Soceity.