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Current Research


Space Plasma Physics and Planetary Science

From a broad perspective my interest lies in understanding plasma acceleration processes and magnetic field modifications in planetary magnetospheres. I am also interested in bridging the gap between magnetospheric and atmospheric sciences by incorporating elastic and inelastic interactions between charged and neutral particles and tracking the mass, energy and momentum feedback between the neutral and ionized populations. This feedback is also tracked via the local influence on the electric and magnetic fields.

Enceladus

Instruments on the Cassini spacecraft discovered a plume of water-ice particles, vapor, and dust grains jetting outward from the southern polar region of Saturn’s moon Enceladus. Perturbations in the velocity and magnetic field of the incident flow seen over an extended region are evidence of mass loading of Saturn’s magnetosphere by ions likely produced via charge exchange in the expanding neutral plume. For this project I have been incorporating neutral fluid components into an existing 3D multi-fluid modeling infrastructure to investigate the interaction between the plume material and the ambient magnetospheric plasma. The ion and neutral fluids interact through charge exchange, and the production and loss of ions and neutrals is monitored through source and loss terms in each fluid species in each grid cell. The model is in the process of being verified against the Cassini spacecraft observations of magnetic field and plasma velocity perturbations and used in conjunction with the CAPS ion energy distributions to determine the importance of ion-neutral interactions for transport of mass and energy near Enceladus. Much of the data analysis work on the project is done in collaboration with the Cassini CAPS team, which is an exciting and dynamic group involved directly with instrument and new science coming out of the most recent observations. Prospective students interested in an Enceladus orSaturn related research project should feel free to contact me.

Enceladus' plume

Mars

There are currently 2 Mars projects that I am currently involved in, the first involves studying Mars atmospheric electrodynamics using a combination of spacecraft observations and simulations. This is truly the testbed for developing the neutral atmosphere coupling to the space plasma environment. Mars provides us with a natural laboratory to study these interactions due the diffuse atmosphere and exosphere and lack of a strong internal magnetic moment. Without a large magnetosphere, a significant fraction of charged particles from the solar wind can interact with the Mars' upper atmosphere creating a region of direct coupling between the magnetized solar wind and the neutral atmosphere. This work is performed in conjunction with several members of the SSL at UC Berkeley who are working on the atmospheric models as well as data analysis for ground-truthing the newly developed coupled models. This project is just getting started, so motivated and interested students should feel free to contact me about research opportunities related to this work. The second project is an ongoing collaboration with C. Johnson at UBC and K. Lawrence at Stanford, which involves examining Mars' ancient atmosphere and the various loss mechanisms responsible for its evolution to the current day state.
Mars atmospheric loss


  Previous and Continuing Research Projects

Ganymede & other Galilean Moons

This project takes us to the Jovian system where recent UV auroral observations of Ganymede and Jupiter have demonstrated that our current understanding of plasma acceleration mechanisms in the magnetosphere (expressed as aurora) is incomplete.  The approach taken to study this system involves using three-dimensional multi-fluid simulations developed by R. Winglee which allow for several different ion species to interact in the system as well as incorporate the ion cyclotron effects into both the momentum and electric field equations.  This powerful tool enables us to study differential heating and acceleration between various ion species sourced from both the incident Jovian magnetospheric plasma and Ganymede's own ionosphere. Using 3D imaging software significant insight has been gained pertaining to the location and morphology of critical boundary layers in Ganymede's magnetosphere, and over several years I developed a suite of diagnostic tools for better comparison/integration with a range of observational data gathered by instruments on the Galileo spacecraft, Voyager spacecrafts, and Hubble Space Telescope's STIS.  This integrated approach yields a more physically accurate and sophisticated picture of how Ganymede and its magnetosphere are modifying Jupiter's magnetosphere and how the plasma is affected within this perturbed region.

I am very much intersted in taking some of the new modeling techniques developed for Enceladus which incorporate ion neutral interactions and applying them to the Jovian satellites, expecially for Io. Prospective students with interests in conducting studies of any of the Jovian satellites should feel free to contact me about potential projects in this area. With the upcoming Juno mission and potentially a future flagship mission to the Jovian system, these topics are seeing some renewed intersted and enthusiam across the community.

Ganymede's magnetosphere and ionospheric density
Fun composite image! Please acknowledge me if you reproduce.

Jupiter

Along with understanding the interactions between Jupiter and Ganymede local to Ganymede's near space environment, I initially worked on some early research pertaining to the study of the Jovian system from a global perspective.  I presented some preliminary results from the Jovian global simulation at the Magnetospheres of Outer Planets conference in the summer of 2002 and findings on ionospheric outflow rates and Io torus stability were shown at the Fall 2002 AGU.  Undergraduate researcher Laurel Rachemeler, now in graduate school at UC Boulder, continued the Jupiter research studying the break-down of corotation and magnetic field warping.  Recent developments were presented at the Fall 2004 AGU by our undergraduate researcher Angela Stickle, now in graduate school at Brown University.  


Previous Research from days of old...

2001: Low Frequency Nuclear Magnetic Resonance(NMR) Spectroscopy: A study of Nuclear Spin Relaxation in 2-tertiarybutyl 4-methyl hydroxybenzene. Senior thesis, Bryn Mawr College , Department of Physics , Adviser Peter Beckmann (paper published 2004!)

2000: The Stability of Liquid Water in Porous Rocks in a Mars-like Environment. Abstract from ASGSB Meeting 2000.  NASA Astrobiology Academy, Ames Research Center, P.I. Chris McKay

1999: Characterization of Light Emitting Diodes for Plant Growth: Power efficiencies for LEDs in bioregenerative life support systems. Abstract from ASGSB Meeting 2001.  Space Life Sciences Training Program, Kennedy Spaceflight Center, P.I.  James Scott Young