PLANETARY MUSINGS

Entries in "Mars"

Graduate Study in Earth and Planetary Science

The Department of Geological Sciences at Case Western Reserve University is currently accepting applications from students interested in pursuing graduate studies leading to M.S. and Ph.D. degrees in the earth, environmental, and planetary sciences. The Department offers flexible, research-intensive programs for graduate students. Applications are accepted on a continuing basis, though students requesting financial support are strongly encouraged to apply by February 1, 2008. Online applications are available through the School of Graduate Studies.

There are several opportunities for students interested in pursuing research in planetary science, particularly in the areas of planetary geology and geophysics, high-pressure and temperature geochemistry, and meteorites working with a group of faculty that includes myself, Prof. Harvey, and Prof. Van Orman.

At present I am collaborating with students to (1) understand the nature of Mars' crust and lithosphere and tectonic activity and (2) the mechanisms responsible for driving Ganymede's magnetic field. (3) I am also looking for graduate students interested in working with me on analyzing data from the MESSENGER Mission to Mercury to understand both the internal and tectonic evolution of that planet Additional opportunities within these may be available depending upon interest. We are also in the process of focusing new study on large lunar impact basins.

I would welcome the opportunity to discuss opportunities for graduate study in planetary science and/or geophysics with interested students (my contact info is available on my webpage).

Papers for the Lunar and Planetary Science Conference

We have two papers accepted for the upcoming 38th Lunar and Planetary Science Conference in Houston. LPSC is the primary planetary science meeting of the year. This year our group will be giving two posters on the origin and interpretation of major tectonic features on Mars and Mercury.

Ritzer, J. A., and S. A. Hauck, II (2007). Influence of external loads on interpretations of lithospheric flexure and tectonics at Isidis Planitia, Mars, Lunar and Planet. Sci., 38, 2244.pdf.

Dombard, A. J., and S. A. Hauck, II (2007). Despinning plus global contraction and the orientation of lobate scarps on Mercury, Lunar and Planet. Sci., 38, 2026.pdf.

These presentations will be made March 12-16, 2007 in League City, TX.

Opportunities for Graduate Study in Planetary Geology and Geophysics

The Department of Geological Sciences at Case Western Reserve University is currently accepting applications from students interested in pursuing graduate studies leading to M.S. and Ph.D. degrees in the earth, environmental, and planetary sciences. The Department offers flexible, research-intensive programs for graduate students. Applications are accepted on a continuing basis, though students requesting financial support are strongly encouraged to apply by February 1, 2007. Online applications are available through the School of Graduate Studies.

There are several opportunities for students interested in pursuing research in planetary science, particularly in the areas of planetary geology and geophysics, high-pressure and temperature geochemistry, and meteorites working with a group of faculty that includes myself, Prof. Harvey, and Prof. Van Orman.

At present I am collaborating with students to (1) understand the nature of Mars' crust and lithosphere and tectonic activity and (2) the mechanisms responsible for driving Ganymede's magnetic field. Additional opportunities within these may be available depending upon interest. We are also in the process of focusing new study on large lunar impact basins and the coupled internal and tectonic evolution of Mercury.

I would welcome the opportunity to discuss opportunities for graduate study in planetary science and/or geophysics with interested students (my contact info is available on my webpage).

Google Mars

It had to happen eventually... Google has decided that one planet just is not enough. 

http://mars.google.com/

It looks like the THEMIS folks at ASU have gotten together with Google to provide some easily accessible data from Mars.  It is pretty limited, but you can zoom around my favorite map of Mars, one made using MOLA laser altimeter data, as well as look at some recent visible and infrared data.

Mars Reconnaissance Orbiter makes it to Mars

The largest and most powerful tool for learning about Mars has just arrived in orbit around that planet.  the Mars Reconnaissance Orbiter (MRO) has the largest camera ever sent to another planet (HiRISE), a hyperspectral instrument (Crism), and a sounding radar (SHARAD) all of which will send back incredible amounts of data about the red planet.  Indeed, it is expected that this one mission will send back 10 times more data than all the other missions to Mars (past and present) combined.  The next few years are going to bring some incredible discoveries.  Congratulations to the whole MRO team!

Check out the news story or go straight to the source at JPL's MRO website.

GEOL 512 and the Martian dichotomy boundary

This semester I am teaching a graduate seminar course centered around some unresolved problems regarding the history of the planet Mars.  The first topic is the origin of the hemispheric dichotomy.  Basically, the northern and southern hemispheres of Mars appear quite different.  The south is a few kilometers higher than the north, the north is smoother than the south, and the surface materials appear younger in the north than in the south.  The image below illustrates the basic idea - the colors are the topography of Mars from the MOLA instrument (a laser altimeter) and the blues in the north are low and the reds and oranges in the south are higher.  Several hypotheses have been put forth, ranging from one or multiple large impacts to internal processes like a past period of plate tectonics (Mars doesn't have plate tectonics today).  We are discussing the available data and how well various existing hypotheses work.  Students will be working on small individual projects related to the problem as well.  As sort of a catalog for myself and other students of Mars the following lists the papers we have been using to motivate our discussions so far.

Continue reading "GEOL 512 and the Martian dichotomy boundary"

Classic paper on gravity and lithospheric stress

Sleep, NH and RJ Phillips, Gravity and lithospheric stress on the terrestrial planets with reference to the Tharsis region of Mars, JGR, 90, 4469-4489, (1985), ADSABS Entry.

I recently re-read most of this classic paper. Trying to put together knowledge on gravity, topography, and tectonics in order to understand the state and evolution of planetary lithospheres is a long-standing problem. For small planets like Mars, membrane stresses (often known as fiber stresses to engineers thinking about pressure vessels) are important (not the case on Earth); these and a few other authors like Turcotte, Banerdt and their co-workers laid out these problems for Mars. Tharsis is most likely largely isostatically compensated, and this is an important first step to understanding circum-Tharsis tectonics. The treatment is relatively complete for its purpose, but we have a bit more data today and we worry about more than just isostatically compensated loading of the planet. However, the discussion of calculating gravitational potentials is lucid and useful and membrane stresses instructive.

Martian magmas

Agee, CB and DS Draper, Experimental constraints on the origin of Martian meteorites and the composition of the Martian mantle, EPSL, 224, 415-429, (2004) http://dx.doi.org/10.1016/j.epsl.2004.05.022

Interesting experimental study of potential martian magmas with the aim to understand the super-chondritic CaO/Al203 ratios in shergottites. Basic, result is that apparently no one-stage melting process can create both the high CaO and Al203 concentrations as well as the CaO/Al203 ratios in the shergottites. Instead, the authors propose deep melting around 5 GPa (near their experimental conditions) that due to garnet produce appropriate CaO/Al203 ratios, followed by olivine crystallization at lower pressure to up the concentrations. They suggest that either a mantle-plume or magma ocean scenario might account for such a situation. (Note, none of these processes account for the FeO and Mg#'s using the proposed starting materials). They conclude with comments on studies that try to use the moment-of-inertia to constrain the composition of the planet.

Musings:
(1) I suspect that the pervasive upper mantle melting that I and others like Reese, Solomatov, Stevenson, etc have talked about, could be another mechanism for the two-stage differentiation. Normal upwelling (or plumes) generate deep melting, that proceeds to shallower levels where olivine crystallizes.
(2) Agee and Draper are probably right about the moment-of-inertia arguments. We don't know enough about the core at the moment, especially its composition. I would guess that once the high-pressure phase diagram of Fe-FeS is known better we might be able to place a minumum limit on the sulfur content of the core with thermal models, but it may be higher than current estimates because models (including mine) overestimate the melting pt depression of S for lack of data.