“Research is what I’m doing when I don’t know what I’m doing.” – Wernher Von Braun
I am a member of the science team for the ChemCam instrument on the Curiosity Mars rover. ChemCam is a camera combined with a laser-induced breakdown spectroscopy (LIBS) instrument, which is a fancy way of saying that we zap rocks to figure out what they are made of. A lot of my work involves developing software to make it easier to analyze data from the instrument and to improve the accuracy of the chemistry that we infer from the spectra. I am also involved in a campaign to use long-distance ChemCam remote micro-imager (RMI) images to study the slopes of Mt. Sharp.
I am also a member of the science team for SuperCam, the next generation of ChemCam, which will fly on the Mars 2020 rover. SuperCam does everything ChemCam can do, but it also can collect Raman spectra (to identify minerals and organics), and near-infrared reflectance spectra (to identify minerals, especially those containing water). Its images will be in color, and SuperCam will also have built-in microphone to record sounds from the surface (wind, rover sounds, and the sound of the laser zapping targets).
Spectral Analysis Tool (PDART)
I am currently leading a project to develop a free, open-source spectral analysis tool designed specifically for analyzing LIBS spectra from instruments like ChemCam and SuperCam. The goal is to provide the scientific community with something easy to use via graphical interface, but powerful and flexible. Among other capabilities, the tool will be capable of preprocessing steps such as masking, continuum removal, and normalization; calibration transfer methods to enable comparison of data from different instruments; and regression methods like Partial Least Squares (PLS) and Gaussian Process regression. The tool is being written in Python, and will make extensive use of the Scikit-Learn machine learning library. This project also involves collecting a suite of laboratory spectra using the ChemCam clone at Los Alamos and a laboratory instrument at Johnson Space Center. All code and data will be made freely available.
Mapping Sinuous Ridges (MDAP)
I am the principal investigator on an effort to produce a high-resolution map of inverted fluvial channels (more generically called “sinuous ridges”) in the northwestern Hellas region of Mars. Inverted channels occur in when the bed of a river becomes more resistant to erosion than the surrounding plains, resulting in a raised ridge that traces the former course of flowing water. Measuring these features can provide estimates of how much water was flowing. Although regular (negative relief) valley networks have been mapped on Mars, nobody has produced a comparable map of inverted channels. In the process of mapping inverted channels, we are also greatly improving the level of detail of the map of valley networks.
Bedding Geometry (MDAP)
I am also leading an effort to measure the bedding geometry of the complex patterns visible in the upper portion of Mt. Sharp in Gale crater. In 2010, I interpreted these as possible cross beds (evidence of ancient sand dunes) but three dimensional measurements are required to better understand these patterns. We will also make similar measurements in the Medusae Fossae Formation, which has been speculated to be similar in origin to the upper part of Mt. Sharp.
Planetary Learning to Advance the Nexus of Engineering, Technology, and Science (PLANETS)
I am a team member on the PLANETS project, which is a NASA-funded partnership between Northern Arizona University, USGS Astrogeology, and the Museum of Science in Boston. We are working to develop several out-of-school units that use planetary science and exploration as the motivation for middle school students to learn more about fundamental science and engineering concepts. Since planetary science is so interdisciplinary and exciting, it is the perfect way to get gets interested in a variety of STEM topics.
I worked with Jim Bell at Cornell for my PhD. My research was focused on preparing for the Mars Science Laboratory Mission. I presented my mapping and geomorphology work on Gale crater at several of the landing site selection meetings, and my work played a role in its eventual selection as a landing site for MSL. My Gale paper is available here (open access).
I also worked on data analysis techniques for laser-induced breakdown spectroscopy, a technique that is used by the ChemCam instrument on MSL. My first LIBS paper compared neural networks and partial least squares for quantitative measurements of the composition of rock slabs. That paper also discussed the effects of target grain size on the accuracy of the derived composition. My second LIBS paper examines several different methods of defining the set of samples used to train the partial least squares model.
In 2008, I wrote tools in IDL that make mosaics of data from the Mars Color Imager (MARCI). This camera has a 180 degree field of view, somewhat like a fish-eye lens, and it returns global maps of Mars daily. My program can search the data archive to make maps of any region on Mars at any time during the Mars Reconaissance Orbiter mission. By choosing the darkest pixel in cases where the data overlaps, I can minimize the effect of dust (bright in red) and clouds (bright in blue).
Summer 2006: NASA Academy Summer Internship
During the summer of 2006 I worked at NASA’s Goddard Space Flight Center with Eric Cardiff on extracting oxygen from the lunar regolith by melting it with concentrated sunlight. The prototype device used a large Fresnel lens to focus light on a sample of lunar regolith inside a vacuum chamber and evolve oxygen. My work involved preparing a larger system for operation. The new system used a 12′ diameter reflective parabolic dish to focus sunlight. Unfortunately, due to design flaws in the vacuum chamber, it had to be redesigned to withstand the extremely high temperatures attained by focusing such a large amount of energy. I was put to the task of doing a thermal analysis of the design to determine what was necessary to allow it to survive. Without thermal analysis software, and with limited experience, we were unable to get a working chamber built by the end of the summer. I did teach myself about vacuum systems and got the chance to work with my hands, which was a nice change.
In addition to individual research, the NASA Academy program involved a group project. We chose to design a mission to Saturn’s moon Enceladus, which has been a target of great astrobiological interest since the discovery of water geysers at its south pole. I was part of the mission architecture team, designing a trajectory that was efficient but also satisfied all the science goals of the mission. The project was a great experience, and gained attention from experts in the field. Our mission concept was one of the first of its kind, and we were invited to present our work at the Enceladus Focus Group meeting prior to the 2006 AAS Division for Planetary Sciences (DPS) conference, and to the Outer Planets Assessment Group (OPAG) – a group of scientists who advise NASA on future exploration of the outer solar system.
Mars Analytical Chemistry Experiment (MACE)
In 2005 and 2006 I worked with Professor Hunter Waite on the Mars Analytical Chemistry Experiment, a 2 Dimensional Gas Chromatography/Mass Spectroscopy (2DGCMS) instrument that was proposed for MArs Science Laboratory. I researched pattern recognition methods for analyzing the data, and developed a simple computer model of one part of the instrument that we could use to simulate results and then apply pattern recognition techniques to the data. My work on this project was the topic of my senior thesis.
Summer 2005: Internship at the Lunar and Planetary Institute
I worked over the summer of 2005 with Dr. Walter Kiefer studying quasi-circular depressions(QCDs) on Mars. QCDs are large depressions that appear in topographic data, but are not visible to the eye. It is likely that they are the remains of very ancient impacts that have been all but covered up by more recent events. I made measurements of the QCD diameter and depth and compared my data with the expected depth for newly formed craters. The difference told us how much the QCDs have been filled in. By studying multiple QCDs in a region, we hoped to learn something about the depositional history of that region. In addition, the data that I gathered has been used in modeling gravity anomalies associated with large basins on mars. In general, gravity is slightly stronger over large basins, implying an increase in density. By knowing the fill thickness, the contribution from the fill can be subtracted from the gravity anomaly. Whatever is left must be due to an uplift of denser mantle material.
Left: a QCD, clearly visible in MOLA topographic data. Right: Viking visible image of the same area.
Summer 2004: Internship at the Harvard/ Smithsonian Center for Astrophysics
I spent ten weeks in the summer of 2004 in Cambridge, Mass. working with Tom Megeath to test a new method of measuring the density of molecular clouds in data from the Spitzer space telescope. Molecular clouds are nebulae of gas and dust where star and planet formation occurs. In many nebulae, there are dark filaments of gas in front of a glowing background. We tried to measure how much of that background radiation was absorbed as it passed through the dust filaments, and by doing so, find out the structure of the dark clouds. The final version of the Spitzer Orion nebula image I was working with was a press release in 2006. Here is the image (click to see the press release):
High Resolution Spectroscopy of a Flare on Barnard’s Star
I worked on this project with Diane Paulson for UROP (Undergraduate Research Opportunity Program) my sophomore year as an undergraduate at the University of Michigan. I came in not knowing anything about programming or working with linux/unix, and came out knowing IDL, some IRAF, and with some interesting results. We identified many emission lines in the flare, some of which were unexpected, including silicon and aluminum. This was a great project that introduced me to research and Diane pointed me in the right direction for my next research experience at the CfA.