Michael Bland

Postdoctoral Associate
Ph.D., Planetary Science, University of Arizona, 2008
B.A., Physics and Geology, Gustavus Adolphus College, 2002

Curriculum Vitae (pdf)

Planetary Geodynamics

I am interested in the geodynamic evolution of solid planetary bodies in our Solar System and beyond. The terrestrial planets, large asteroids, icy satellites, and Kuiper-belt objects of our solar system each has a unique geophysical history; yet each has been influenced by similar processes. By modeling the thermal and tectonic history of these bodies I strive to advance understanding of the evolution of specific planetary objects, the modification of their surfaces, the general tectonic and thermal processes that operate on classes of bodies, and the evolution of the Solar System as a whole.

The evolution of icy satellites

Icy satellites provide a unique perspective on the geophysical processes that operate in our solar system. As a class, they are large in number (relative to terrestrial planets) providing ample opportunity for comparative planetology. The geologic record preserved in their varied surfaces is expansive. The potential for coupling between their thermal and orbital evolution leads to complex geodynamic histories. They have perhaps the greatest astrobiological potential of any object (or set of objects) in the Solar System. They provide a unique counterpoint to the terrestrial planets. On these bodies, the same physical principles that guide our understanding of terrestrial planets (e.g., applied stress results in strain; energy is conserved) must be applied to a unique material (water ice) in a unique environment (the cold outer Solar System). The result is a panoply of unique surfaces that range from the towering ice pinnacles of Callisto, to the broad swaths of "grooved" terrain on Ganymede, to the plumes of material erupting from Enceladus' south pole.

Tectonic deformation

Using numerical (finite element) modeling I have examined the formation of features such as Ganymede's grooved terrain, Enceladus' equatorial ridges and troughs, and Europa's long-wavelength folds. These investigations have two primary goals. The first goal is to understand how a specific feature formed. I attempt to determine how much strain was required, constrain the strain rate that was necessary, and perhaps most importantly, evaluate the thermal gradient (i.e., the heat flow) needed to produce the observed deformation. By constraining these basic parameters we learn more about the evolution of the body itself and perhaps something about the Solar System in general. The second goal is to understand how ice lithospheres generally behave when stressed or strained. Through modeling, I am currently investigating what mechanical properties (e.g., yield strength, ductile flow properties, semi-brittle behavior, strain localization) an ice lithosphere must have to produce the large-amplitude surface deformation observed.

Thermal evolution

While modeling the formation of tectonic features helps to constrain the geophysical conditions present on a satellite at some point in its geologic history, we gain additional insight by modeling the thermal and physical evolution of the body directly. Investigating satellite evolution involves trying to understand how energy is released or dissipated within, is transported through, and escapes from a satellite, and whether those processes lead to physical changes in the satellites internal structure. Because satellites often exist in orbital resonances with each other, significant amounts of tidal energy can be dissipated within satellite interiors over long time-scales. Thus, the geophysical evolution of satellites is coupled to their orbital evolution, leading to complex feedback between the two. I have investigated the effects of thermal-orbital coupling on the evolution of Jupiter's satellite Ganymede, including whether an epoch of tidal dissipation in it past may have produced extensive melting and global expansion, and enabled the production of its intrinsic magnetic field. Currently, I am investigating the role of tidal dissipation in contributing to Ganymede's highly differentiated state (e.g., the formation of a metallic core).

M. T. Bland, and W. B. McKinnon 2009. Modeling fold formation in ice lithospheres: A search for Europa's missing contractional strain. In Prep.
M. T. Bland, W. B. McKinnon, and A. P. Showman 2009. The effects of strain localization on the formation of Ganymede's grooved terrain. Icarus, submitted.
Mitri, G., M. T. Bland, A. P. Showman, J. Radebaugh, R. M. C. Lopes, J. I. Lunine, R. T. Pappalardo, and the Cassini RADAR team 2009. JGR-Planets, in revision.
Bland, M. T., A. P. Showman, and G. Tobie 2009. The thermal-orbital evolution and global expansion of Ganymede. Icarus 200, 207-221.
Bland, M. T. 2008. The tectonic, thermal, and magnetic evolution of icy satellites. Ph.D. Dissertation, University of Arizona.
Bland, M. T., A. P. Showman, and G. Tobie 2008. The production of Ganymede's magnetic field. Icarus, 198, 384-399.
Bland, M. T., R. A. Beyer, and A. P. Showman 2007. Unstable extension on Enceladus. Icarus 192, 92-105.
Bland, M. T. and A. P. Showman 2007. The formation of Ganymede's grooved terrain: Numerical modeling of extensional necking instabilities. Icarus 189, 439-456.

314-935-4810	mbland at levee dot wustl dot edu
314-935-7361

Last revised:
09-Nov-2009

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