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Entries in "Planetary Science"Video on MESSENGER 1st flyby of MercuryThe American Museum of Natural History just released this great Science Bulletin video story highlighting the MESSENGER mission and the 1st flyby of Mercury back in January. Iron snow on MercuryOne of the active areas of research in our group is developing understanding of mechanisms that can drive convection inside the metallic cores of solid planets and moons. Why? To understand what may be driving magnetic fields. Previously, we had demonstrated that in contrast to the Earth, Ganymede's magnetic field could be the result of solid iron precipitating at the core-mantle boundary and "snowing" inward, driving compositional convection. Based on new experimental results by colleagues Bin Chen and Jie Li at the University of Illinois we have shown that a similar set of results is possible for Mercury. The effect at Mercury is pronounced by non-ideal melting behavior of the Fe-FeS system at modest pressures. Indeed, it turns out that Mercury could also evolve to a state of having to distinct and separated zones of snowing iron in its core. All of these results will be useful in understanding the results that will be gained by the MESSENGER mission to Mercury once it gets into orbit.
Graduate Study in Earth and Planetary ScienceThe 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). Predicted recovery of Mercury's internal structure by MESSENGERA major focus of research in our group over the last several years and now looking forward with our involvement with the MESSENGER is the planet Mercury. A question of primary interest to the scientific community is the origin of the planet's large bulk density and the nature of its core. Recent work by Jean Luc Margot of Cornell and colleagues recently demonstrated that Mercury likely has a core that is at least partially molten. This is an important advance, and the MESSENGER mission will bring more, particularly through measurement of the planet's low-degree gravity field. In preparation for MESSENGER's arrival we have calculated a series of models of Mercury's internal structure in order to estimate how well new data will constrain the state of the interior. Working with Sean Solomon (CIW) and Derek Smith (former Case student now pursuing a Ph.D. at Dartmouth) we have calculated that within current estimates of the quality of MESSENGER's forthcoming measurements that it may be possible to determine the size and density of Mercury's core and mantle with considerable confidence, especially for a body for which we have no samples and placed no landers nor seismometers on its surface. The results of this work were recently published in Geophysical Research Letters. Hauck, Steven A., II, Sean C. Solomon and Derek A. Smith, Predicted recovery of Mercury's internal structure by MESSENGER, Geophys. Res. Lett., 34, L18201, doi: 10.1029/2007GL030793 (2007). Article Venus Flyby 2Late in the afternoon on Tuesday, June 5, 2007 the MESSENGER spacecraft is going to slingshot around Venus for the second time on it way to Mercury. The spacecraft will use Venus' gravity to assist in its journey to the solar system's inner most planet. During the first flyby of Venus last October the planet was on the far side of Sun from Earth (solar conjunction) and communication with the spacecraft was difficult at best, so no scientific data were taken, and MESSENGER flew by in a safe configuration with a closest approach of nearly 3000 km. On Tuesday the spacecraft will flyby as close as about 340 km and will be taking data this time with most of its instruments. The instruments onboard MESSENGER are optimized for surveying Mercury, however several are capable of taking important observations of Venus, particularly its atmosphere. It is also a great "dress rehearsal" for our first flyby of Mercury on January 14, 2008. There should be some exciting data from our sister planet coming down from MESSENGER in the next several weeks after the flyby. Several of these data will be compared with coordinated observations by ESA's Venus Express. We will be looking forward to some interesting new results in the coming months... Papers for the Lunar and Planetary Science ConferenceWe 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. These presentations will be made March 12-16, 2007 in League City, TX. Opportunities for Graduate Study in Planetary Geology and GeophysicsThe 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). Sulfur's impact on core evolution and magnetic field generation on GanymedeRecently, we have been working to understand whether Ganymede may have a relatively exotic way of driving convection in a fluid portion of a metallic core that would in-turn generate its magnetic field. In the Earth, convection in the outer core is driven by some combination of thermally-generated buoyancy as the core cools and compositional buoyancy from the release of some light element at the inner core outer core boundary and then rising to shallower levels. The latter is energetically efficient because it isn't subject to the inefficiency of a heat engine. On Ganymede the same process may also hold, however the phase diagram of a potential core alloy (Fe-FeS) is different at the low pressures in Ganymede's core compared to the much higher ones deep in the Earth. This difference allows for the possibility that solid iron might precipitate shallow in the core and fall through the core and potentially driving the magnetic field. It is also possible that if the core is very sulfur rich solid FeS might float up from deep in the core and also drive core convection. Working Jonathan Aurnou (UCLA) and Andrew Dombard (APL) we have outlined the potential consequences of these relatively unique modes of core evolution in a recently published paper: Continue reading "Sulfur's impact on core evolution and magnetic field generation on Ganymede" Google MarsIt had to happen eventually... Google has decided that one planet just is not enough. GEOL 512 and the Martian dichotomy boundaryThis 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" Looking for Graduate StudentsIt is that time of the academic year again - I and the Department of Geological Sciences as a whole are seeking qualified students for our graduate program. Current research strengths in the department include: surface processes, soil erosion, sediment transport, geologic sequestration of carbon, geochemistry, planetary materials, planetary geology and geophysics, and high-pressure mineral physics and chemistry. Financial assistance may be available for qualified applicants interested in pursuing M.S. or Ph.D. degrees. For more information, please see http://geology.case.edu. | ||||
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