Throughout most of my graduate school and my professional career, my research has focused on terrestrial space physics, the study of plasma and fields in the near-Earth space environment. However, even when I started down this path, I knew that my ultimate goal was to take the knowledge gained by studying Earth, which is much more accessible and for which there are much more data, and apply it to the near space environments of other planets.
For the past few years, I have been focusing a large portion of my time on modeling the complexities of the nighttime ionosphere of Mars. In the absence of a globally coherent magnetic field but with multiple crustal magnetic anomalies, Mars has a very complex magnetic topology. Interplanetary particles which can ionize the upper atmosphere only have access to the nighttime atmosphere at particular locations determined by the interaction of the crustal magnetic fields and the interplanetary magnetic field. Additionally, recent observations show that some of the precipitating ionizing electrons appear to have undergone an acceleration process (interestingly, not unlike those found in Earth?s auroral regions). These features lead to a highly spatially inhomogeneous ionosphere on the night side. Last year, I published our first modeling results on the heterogeneity of the Martian nighttime ionosphere by using interplanetary electron observations as input to an electron transport code. I have continued to work with colleagues at the University of California, Berkeley, the University of Michigan, and the University of Alaska to model time variations in and electrodynamic consequences of the ionospheric structure. As seen in my CV, I am the principle investigator on two NASA grants to continue this work. Additionally, I am a co-investigator on a proposal submitted last year to develop a new model of the Martian ionosphere with colleagues from UC, Berkeley, Georgia Institute of Technology (the PI institution), the University of Washington, and the University of Michigan.
In addition to studying the ionosphere of Mars, I am also interested in studying the plasma environment of the Moon. The goal of this work is not only to learn more about plasma physics occurring near the Moon, but also to learn more about the electrodynamics of Earth deep magnetosphere at lunar altitudes. When the Moon is in Earth?s magnetosphere, it creates a ?shadow? in the particle flux. From measuring the properties of this shadow, the electric field in Earth?s magnetosphere, a fundamental quantity that is very difficult to measure in this region with other techniques, can be determined. Not only can we learn more about the Moon but also Earth?s magnetosphere. This past year, I was the principle investigator on a proposal submitted to NASA to do this type of work using Lunar Prospector data. Also, data form the Japanese Kaguya (SELENE) spacecraft currently orbiting the Moon and from the upcoming ARTEMIS (Acceleration, Reconnection, Turbulence, and Electrodynamics of the Moon?s Interaction with the Sun) mission (slated to begin in 2010, pending technical review) would be very instrumental in this type of work.
I am also interested in terrestrial space physics, mostly in the area of global auroral imaging. Since 1997 (throughout most of my graduate and subsequent professional career), I have worked with data from the Ultraviolet Imager (UVI) onboard the Polar spacecraft that imaged the entire auroral oval (northern, then a few years later, southern) from high altitude. The Polar spacecraft was decommissioned this past year, so no new data will be available. However, over the twelve year life of the instrument, there is a large archive of global auroral images, and there are many projects that can be done using this long interval of data. Currently, I am the principle investigator on a NASA grant with colleagues from the University of Alabama in Huntsville and the Naval Research Laboratory to study how auroral emissions decay away as a function of season, and how aurorae behave in both the northern and southern hemispheres during solstice conditions.
In addition, I have been supporting several colleagues nation- and world-wide in their analysis of THEMIS (Time History of Events and Macroscale Interactions during Substorms) data in Earth?s magnetosphere. Up until February of last year, UVI was providing global auroral images over the southern hemisphere. These data have been invaluable for comparisons with magnetospheric particle and field data to try to understand how the aurora is related to magnetospheric dynamics. Even though no new data will be gathered, it is my hope and expectation that these collaborative efforts will continue into the near future. The knowledge gained through this type of study can be of great use when applied to other planets where we know auroral processes are occurring.