“Research is what I’m doing when I don’t know what I’m doing.” – Wernher Von Braun
Cornell
In 2009 I will spend 10 weeks at Johnson Space Center as part of my NASA GSRP fellowship. My project involves using Laser-Induced Breakdown Spectroscopy (LIBS) to collect spectra of various rock samples, and writing code to derive quantitative information from those spectra. The Mars Science Laboratory (MSL) rover will carry a LIBS instrument, and my fellowship work will help to maximize the usefulness of that instrument by allowing rapid analysis and identification of rocks an minerals.
MSL will carry a laser similar to the one that I will use in the lab.
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). I am currently using this program to make time-lapse animations of landing sites on Mars to detect changes in albedo.
A color MARCI mosaic of Valles Marineris made with my IDL programs.
MARCI color time lapse view of Gusev Crater, showing the dramatic change in dust cover after the 2006 dust storm.
I also used Context Camera (CTX) images and Thermal Emission Spectrometer (THEMIS) thermal inertia data to create a detailed unit map of the potential MSL landing site and traverse in Gale Crater. I will be using high-resolution imaging, topography and composition data from MRO to study the landing site in great detail and interpret the origin of the units and the 5km stack of sediments in the crater.
Unit map of the Gale Crater landing site and traverse.
During the summer of 2007 I used data from the OMEGA (Observatoire pour la Minéralogie, l’Eau, les Glaces et l’Activité) instrument on Mars Express to look at potential landing sites for the Mars Science Laboratory rover (MSL). I worked with Briony Horgan to develop programs that generate mosaics of OMEGA data for the region of interest and generate maps indicative of minerals of interest, such as phyllosilicates or sulfates. I used my maps of the Northern Meridiani region to contribute to the 2nd MSL Landing Site Workshop in October of 2007, and recently wrote a paper summarizing the science results of my mapping work. I presented a summary of this work at the 39th Lunar and Planetary Science Conference (LPSC) in March 2008.
a) A map of the hydration band depth (indicative of water-bearing minerals) in Meridiani. b) A map of the sulfate parameter (indicative of the abundance of sulfates) in Meridian. c) Phyllosilicates (red) and sulfates (yellow) in Meridiani. Insets show phyllosilicate and sulfate detections near the North Meridiani and East Meridiani MSL landing sites.
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. Unfortunately 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 a bit, 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. We were constructing an instrument that used 2 Dimensional Gas Chromatography/Mass Spectroscopy (2DGCMS) to analyze samples and detect organic (carbon bearing) compounds with enough sensitivity to measure the isotopic abundances and identify what the original compound was. It was originally proposed, but ended up not being selected, as an instrument on the Mars Science Laboratory. The idea was to understand the history of organic molecules on Mars, because data from the Viking lander showed that Mars has even less organic material than would be expected from meteorites and comets. We want to know where these “missing” organics are. Also, organic molecules can tell you a lot about the history of the planet and help improve our understanding of the major (bio)geochemical cycles. And, of course, they can indicate whether there was ever life there. Living things (on Earth, at least) process organics in such a way that they leave certain “biomarkers” in the molecules themselves that the instrument will be able to detect.
I ended up spending about half of a semester researching pattern recognition, but it’s a huge subject, and I was/am not a chemist or computer scientist so it was slow going. Then, for the last part of the semester I was given the assignment to look for programs that can do mass-spectral deconvolution and identify compounds. I found one such program, AMDIS from NIST. It was free and apparently very powerful but, after two months of fighting tooth and nail to get IDL to write data in a format that AMDIS could read, I discovered that someone at NASA Goddard had a program that did what I wanted already. Of course, it then turned out that AMDIS couldn’t do what we wanted it to with the data.
We put the problem of mass spectral deconvolution on hold for a while and began working on developing a computer model of the instrument that we could use to simulate results and then apply pattern recognition techniques to the data. The instrument consists of several components: there are two gas chromatograph (GC) columns, one separates components by mass, the second separates by polarity. These columns are connected by a thermal modulator (TM). Normally, as gas travels through the columns, it spreads out, resulting in broad peaks in the final data that are harder to interpret. The TM counteracts this effect. It is chilled by flowing air so that when the solute reaches the TM, it is stopped dead in its tracks. This concentrates the broad peaks into distinct packets of solute. The TM is then resistively heated by running a strong electric current through it. The heating releases the concentrated solute bands into the second column. I created a simple computer simulation of the TM and incorporated that into our model. 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 just what their name implies: 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. I presented a poster on my work at the Lunar and Planetary Science Conference in March 2006.
In addition, the data that I gathered has been used by other interns 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 on brand-new Spitzer data. I learned a lot about research and had a blast with the ten other interns. The goal of my project was to test a new method of finding the density of molecular clouds, which are 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. At the end of the summer, my results were not conclusive, but we think that with some more work, the method has potential.
In January 2005, I went to San Diego to present a poster based on my summer’s research at the American Astronomical Society meeting. 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. 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 a whole slew of emission lines in the flare, some of which were unexpected. Among these were silicon and aluminum. Looking back, I realize what took me two semesters to do I could do now in a fraction of the time. This was a great starter project though, and Diane pointed me in the right direction for my next research experience at the CfA.
