My current research focuses on two main areas of interest:

1. Understanding the chemical composition and evolution of the martian crust/mantle system:

Space exploration has focused intently on Mars because, of all the terrestrial planets, its surface was believed to most resemble that of Earth – and thus appeared to be the best candidate for supporting extraterrestrial life in our solar system. However, over the past decades, a variety of orbiter and lander missions have performed a wide suite of experiments showing that the chemistry of Mars differs in several key aspects. Using the wealth of mission data available, I seek to constrain the bulk chemical composition of the martian crust and further explore the implications of such a composition in relation to the martian crust/mantle system. Also of particular interest is the degree to which the martian surface chemistry is a reflection of surficial weathering rather than primary igneous processes.

Selected Publications:
          B.C. Hahn, S.M. McLennan, G.J. Taylor, W.V. Boynton (2005), Integrating Global-Scale Mission           Datasets – Understanding the Martian Crust, LPS XXXVI, Abstract #1853.

2. Modeling the physical and chemical weathering processes effecting the martian surface:

The Mars Exploration Rover (MER) missions have sampled a variety of rocks on the martian surface. Key to these measurements is understanding how aqueous interactions have altered the chemistry of these studied samples. Additionally, physical weathering, primarily by aeolian abrasion, has eroded rock surfaces. I seek to constrain the degree of both physical and chemical weathering given the martian surface environment and timescales for erosion to take place.

Mars Exploration Rover (MER) and 2001 Mars Odyssey Gamma-Ray Spectrometer Missions:

In April 2004, I was named a Student Collaborator for the Mars Exploration Rover (MER) Mission. From April through September 2004, I worked at the Jet Propulsion Laboratory in Pasadena, CA. I assisted in the daily planning of science experiments for the Spirit and Opportunity Rovers. I also held rotating positions as lead for several Science Theme Groups (Geology; Mineralogy/Geochemistry; and Soil and Rock Physical Properties); the Long-Term Planning lead; mission Documentarian; and Science Operations Working Group (SOWG) Chair – who manages the science planning and execution for a given rover planning day. The MER mission has been remarkably successful – both rovers continue their explorations today. I am still a Student Collaborator and daily mission planning continues remotely here at Stony Brook at our Mars Exploration Program Node.

In May 2005, I also became a Student Collaborator on the 2001 Mars Odyssey Gamma-Ray Spectrometer (GRS) instrument team. GRS is used to map elemental abundances and water abundance on the martian surface. Like MER, GRS has shown longevity far beyond its original lifespan. As an orbiting instrument, GRS does not require the same day-to-day operational support that the surface vehicles of MER do. However, I take part in weekly science teleconferences and attend team meetings (held several times a year) where mission scientists interpret the latest data returned from the GRS instrument suite.

Previous research projects:

Quantifying long-term tectonic reduction in continental area using space-based geodesy: My Master’s thesis work studied the long-term effects of plate tectonics on the Earth’s continental crust. Plate tectonics processes change the areal extent of Earth’s continents – i.e., area is lost during continent collision and gained during rifting. Using GPS data from several global networks to define present-day plate velocity vectors, we constrained the current rate of areal change in the continental crust. Without a counter-acting process such as sedimentation at continental margins or the addition of new continental volume through magmatism, plate tectonics will reduce continental area. The long-term effect of plate tectonics is a significant reduction in continental area over a Wilson Cycle timescale (~500 million years) with important implications for continental crustal evolution.

Selected Publications:
          Hahn, B.C., Kreemer, C., Holt, W.E., Silver, P.G., Haines, A.J. (2005) New Constraints from           Space-Based Geodesy for Tectonic Reduction of Continental Area, Science (submitted).

          Hahn, B.C., Kreemer, C., Holt, W.E., Silver, P.G., Haines, A.J. (2004) Building on Current           Space-Based Geodesy to Infer Long-Term Tectonic Reduction in Continental Area, EOS Trans.           AGU, 85(47), Fall Meet. Suppl., Abstract G41A-08.