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.

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 we incorporate 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 will be 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.



Mars
This project involves examining Mars' ancient atmosphere, and its loss through various processes.


  Continuing Research Projects

Ganymede
For this project my interest lies in 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. 

Preliminary results for Ganymede simulations are here  Link to 2004 GRL paper: Multi-fluid simulations of Ganymede's magnetosphere. Link to 2006 GRL paper: The role of ion cyclotron motion at Ganymede. Link to PhD Dissertation. Link to 2007 JGR paper: Ion energization in Ganymede's magnetosphere: Using multi-fluid simulations to interpret ion energy spectrograms. Coming Soon!

Jupiter
Along with understanding the interactions between Jupiter and Ganymede local to Ganymede's near space environment, I initially worked on some early research (and now continuing group 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.  Then undergraduate researcher Laurel Rachemeler, now in graduate school at UC Boulder, continued the Jupiter research studying the break-down of corotaion and magnetic field warping.  Recent developments were presented at the Fall 2004 AGU by our undergraduate researcher Angela Stickle.  Research on ion lifetimes as well as comparisons to plasma and magnetic field data throughout Jupiter's magnetosphere is ongoing.

•       Results from the preliminary global simulations can be viewed here .
•       Results from the ionospheric outflow study can be viewed here.
• Recent developments pertaining to ion lifetimes in Jupiter's magnetosphere will be posted soon.
  

    The past few years I have become interested in the wonderful world of parallel computing and learning how to make all of these simulations take a lot less time to run.  I had the privilege of participating in a NASA summer program in 2003 to learn about parallel computing techniques, applications, and the availability of such resources.  For information on the program hosted by NASA Goddard to learn about high performance computing go to the homepage for the NASA Summer School for High Performance Computational Earth and Space Sciences.