I work on, or have worked on, a number of projects, ranging from scientific investigations to engineering design. My work spans a number of themes and years, and some projects are on-going while others are done, for now.
Climate Dynamics of Atmospheric Collapse on Mars
Due to the relatively high condensation temperature of carbon dioxide, the Martian atmosphere, which is 95% CO2, can completely condense onto the planetary surface under the right conditions. Most of my PhD thesis work focused on understanding how these conditions for global scale condensation of the atmosphere, often called atmospheric collapse, are a function of CO2 inventory, planetary obliquity, solar luminosity, and atmospheric heat transport. I have published this work in Icarus.
Idealized studies of Martian atmospheric collapse using a GCM. I investigated how the inclusion of non-parametric, time varying heat transport affects the onset of atmospheric collapse. I found that the range of obliquities and total CO2 inventories for which the Martian atmosphere collapses is larger than predicted.
Meridional Transport of Energy during Atmospheric Collapse on Mars. We use Reynolds decomposition to study the meridional eneragy transport in a collapsing atmosphere on Mars. The condensational flow due to CO2 condensation plays an important role in controlling the onset and maintenance of atmospheric collapse.
Hydrology of Terrestrial Planets
Though the existence and nature of an atmospheric hydrology varies greatly in our solar system, I am trying to understand how the various types of rainfall and groundwater are related between the different terrestrial planets. So far, my work has focused on Mars and Titan.
Evaporation, Precipitation, and Convection on Titan My newest project moves my work from the global scale to the mesoscale. Using a mesoscale version of WRF modified for Titan (which I call mtWRF, i.e. 'mesoscale Titan WRF'), I am investigating the physics that control evaporation, precipitation, and convection that occur over the lakes of Titan. Applications of this work include: understanding lake effect cloud formation, investigating possibility wave regimes of the lakes, and connecting lake mesoscale dynamics to the global-scale hydrology.
Precipitation and aridity on ancient Mars. Even if we assume that ancient Mars had a much thicker atmosphere and therefore a much warmer climate, the Martian climate would still have been much drier than is often assumed. Simulating a large ocean in the northern hemisphere basin still only generates a planet with a wet northern hemisphere and an extremely dry deep southern hemisphere. My work shows how the large scale circulation in conjunction with the topographically controlled distribution of water conspire to keep even a warm Mars pretty dry.
In four years working at JPL I experienced the entire flight project development cycle, from preliminary design to launch. I worked on advanced concept design, technology development, instrument design, science operations, and instrument/payload system engineering, as a junior member on large teams as well as leader on small teams. My projects included: Pluto Kuiper Express, Europa Orbiter, Solar Probe, Mars Reconnaissance Orbiter (MRO), Deep Impact, MARVEL (a Mars Scout proposal), and the Terrestrial Planet Finder Coronagraph. The majority of my time was spent working as a payload system engineer on MRO, a science operations engineer on Deep Impact, and the instrument engineer for the occultation spectrometer on the MARVEL Scout proposal.
The Mars Reconnaissace Orbiter continues to provide unprecedented spatial and spectral observations of the Martian surface and atmosphere. As a payload engineer, I was an interface between the instrument teams and the spacecraft team through the early phases of the mission development (Phase A through C, in JPL lingo). I specifically worked with the instrument teams responsible for the Context Camera Experiment (CTX), the Mars Climate Imager (MARCI), and the Mars Climate Sounder (MCS).
I was lucky to be invited to work on the Deep Impact science team as a science system engineer. Working with one of the Deep Impact co-Investigators, Ken Klaasen, I was responsible for developing the lunar calibration observations as well as the training for science operations during flight. Both graduate school and personal events kept me from participating in the encounter, but when the Deep Impact impactor vehicle struck the Temple-1 comet, I was awake in the middle of the night savoring the images from this innovative mission.
My first flight mission, however, was the OPAL spacecraft, which was designed and built at Stanford by students in the Space Systems Development Laboratory (SSDL). SSDL at the time was run by Professor Bob Twiggs. Twiggs envisioned that Masters students at Stanford would design and build a spacecraft over the course of three quarters as part of his space system engineering class. OPAL was one of the first attempts to do that. The Orbiting Picosatellite Automated Launcher (OPAL) was a student designed and built spacecraft that would launch even smaller satellites into orbit, i.e. the 'picosatellites'. The picosatellites were supplied by Santa Clara University and the Aerospace Corporation. When I attended Stanford, OPAL was in the final phases of assembly and test. I got involved in testing the launcher mechanism as well as the complete satellite. Eventually launch in January 2000, OPAL was a successful spacecraft but a failed teaching experiment.
Whereas Twiggs wanted a satellite built in nine months, OPAL took multiple years to be designed and built, thus failing to give a complete spacecraft experience to a single year of Masters students. Twiggs saw that even a small satellite like OPAL was too large and ambitious for a three quarter class. This insight would lead Twiggs and colleagues to develop the cubesat standard, which in its simplest format provides a platform for designing and building a fully functional spacecraft in one academic year. I essentially was a guinea pig in the crucible of the cubesat revolution.