Graduate Student Spotlight

Graduate Student Spotlight: Zachary Torrano

Zachary Torrano received his B.S. in Environmental Geosciences from the University of Notre Dame in 2015, and is currently enrolled in the final year of his Ph.D. at ASU, advised by Prof. Meenakshi Wadhwa.

As an undergraduate, Zack conducted nuclear forensics research in the University of Notre Dame’s High Temperature Isotope Geochemistry Laboratory from 2013–2015, and meteorite research as part of the Lunar and Planetary Institute Summer Intern Program in Planetary Science in 2014.

Zachary TorranoZack’s dissertation research involves the isotopic analysis of meteorites and their components to address outstanding questions about the dynamics and evolution of our early Solar System. His particular focus has been on mass-independent isotopic anomalies in the neutron-rich isotopes of Cr and Ti. These isotopes have a nucleosynthetic origin in supernovae and can be used to trace the incorporation of supernova materials into our Solar System, provide constraints on Solar System dynamics and mixing processes, and provide information on the genetic relationships between meteorites. To this end, he performs high-precision isotopic measurements using the Neptune MC-ICP-MS in ASU’s Isotope Cosmochemistry and Geochronology Laboratory.

His recently published paper "Titanium isotope signatures of calcium-aluminum-rich inclusions from CV and CK chondrites: Implications for early Solar System reservoirs and mixing", reported the Ti isotopic compositions of several calcium-aluminum-rich inclusions (CAIs), which were the first solids to form in the early Solar System. These results showed that CAIs from CV, CK, CO, CM, and ordinary chondrites formed in a common CAI-forming region that preserved some isotopic variability. This paper received an honorable mention for the 2018 Nininger Meteorite Award.

As well as taking an active role in the Center for Meteorite Studies outreach activities, such as Earth and Space Exploration Day, and ASU Open Door, Zack works closely with Center Meteorite Curator Dr. Laurence Garvie to select meteorites for his analyses. He is currently working with Center Assistant Research Scientist Dr. Jemma Davidson to reclassify a meteorite using Field Emission Electron Probe Microanalyzer data.

Zack TorranoIn 2019, Zack was a recipient of the highly competitive and prestigious Future Investigators in NASA Earth and Space Science and Technology (FINESST) award.  His proposal, "Using three isotope systems (Cr, Ti, and O) to address two important questions in planetary science via one sample suite of ungrouped chondrites: 3, 2, 1, Go!", was one of only 29 selected from over 290 applications in the Planetary Science division.

Additionally, Zack was awarded Nininger Student Travel Awards in 2017 and 2018, a Barringer Crater Company Travel Award in 2017, a Planetary Studies Foundation Travel Award in 2019, and a Graduate Excellence Award from the College of Liberal Arts and Sciences in 2018. In 2019, he received a safety award from the School of Earth and Space Exploration, and he continues to promote a culture of safety, accuracy and precision in the Class 1,000 Isotope Cosmochemistry and Geochronology Laboratory.

Zack regularly presents his research at the annual Lunar and Planetary Science Conference, as well as the annual meeting of the Meteoritical Society.  Click on the links below to read his most recent publications and abstracts!


Torrano Z. A., Brennecka G. A., Williams C. D., Romaniello S. J., Rai V. K., Hines R. R., and Wadhwa M. (2019) Titanium isotope signatures of calcium-aluminum-rich inclusions from CV and CK chondrites: Implications for early Solar System reservoirs and mixing. Geochimica et Cosmochimica Acta 263: 13-30.

Titanium Isotope Compositions of Refractory Inclusions: Implications for Nebular Mixing
Z. A. Torrano, V. K. Rai, M. Wadhwa
50th Lunar and Planetary Science Conference (2019), Abstract #1501

Z. A. Torrano, V. K. Rai, M. Wadhwa
49th Lunar and Planetary Science Conference (2018), Abstract #2405











Graduate Student Spotlight: Emilie Dunham

Emilie DunhamEmilie Dunham received her B.S. in Astronomy (with minors in Geology and Physics) from Case Western Reserve University in 2014.  As an undergraduate student, Emilie worked with Dr. Ralph Harvey on comparing the petrology of martian meteorites and dolorites to understand the process that formed lithologic boundaries in the martian meteorite EETA79001. Excited to continue her meteorite studies, and to combine her astronomy background with geology, she enrolled as a Ph.D. student in the School of Earth and Space Exploration at ASU.
Emilie’s primary research in the Center for Meteorite Studies (CMS) aims to understand early Solar System processes by determining chemical and isotopic compositions of meteorites. To this end, she uses the Secondary Ion Mass Spectrometer (SIMS) at ASU to measure the abundances of beryllium and boron isotopes in calcium- and aluminum-rich inclusions (CAIs) found in carbonaceous chondrites, with the goal of deFurnaceDroppedCrucibleciphering the irradiation environment during Solar System formation. As the first solids to crystallize from the nebular gas surrounding our protostar, CAIs recorded important clues about the events that occurred in the early Solar System.
As part of this project, Emilie has been synthesizing her own glass standards by melting oxide powders at high temperatures (read more about this exciting process here). These glasses will be used as SIMS standards for analytical comparison to meteorite materials.
Emilie’s secondary project involves determining the composition of the intriguing Kuiper Belt Object Haumea.  Located near Pluto, and of approximately one third Pluto’s mass, Haumea is covered in a shell of ice and is one of the fastest spinning bodies in the Solar System, completing a full rotation every ~4 hours! This rotational speed has caused Haumea to flatten into an oblong “football” shape.  Emilie is modeling Haumea’s unique shape using an N-body code
An N-body code is a tool widely used in astrophysics to simulate a system of particles under the influence of physical forces, such as gravity, to investigate dynamic processes
in order to constrain its core composition – data from these simulations could provide valuable information on Haumea’s potential habitability!
Emilie is an active participant in the Center’s public outreach events, representing the CMS at ASU’s Night of the Open Door (a signature event of the AZ Sci-Tech Festival), Earth & Space Exploration Day, ASU Homecoming, and Phoenix Comicon. While at ASU, she continues to pursue her interests in teaching; she has been a graduate teaching assistant in the School of Earth & Space Exploration, a Sundial mentor, and a Graduate Partners in Science Education mentor. 
Emilie was awarded the prestigious NASA Earth and Space Science Fellowship (NESSF) in 2016.  The NESSF program awards students from accredited U.S. universities pursuing Master of Science or doctoral degrees in Earth and space sciences, or related disciplines.
Emilie regularly presents her research findings at the annual Lunar and Planetary Science Conference, as well as annual meetings of the Meteoritical Society – click on the links below to read her most recent abstracts!
E. Dunham, S.J. Desch, V. Perera and S.R. Schwartz
48th Lunar and Planetary Science Conference (2017), Abstract #2438
E. Dunham, M. Wadhwa and S.J. Desch
48th Lunar and Planetary Science Conference (2017), Abstract #1507
E. Dunham, M. Wadhwa, S. Simon, and L. Grossman
79th Annual Meeting of the Meteoritical Society (2016), Abstract #6222
Further Evidence of Beryllium-10 Heterogeneity in the Early Solar System Inferred from Be-B Systematics of Refractory Inclusions in a Minimally Altered CR2 Chondrite
E. Dunham, M. Wadhwa, R. Hervig, S. Simon, L. Grossman
47th Lunar and Planetary Science Conference (2016), Abstract #2723

Prajkta Mane

_DSC5548Prajkta Mane received her B.Sc. in Geology from the University of Mumbai (St. Xavier’s College) in 2008, followed by her M.Sc. in Applied Geology from the Indian Institute of Technology (Bombay) in 2010.

After receiving her M.Sc., Prajkta worked as a Project Associate at PLANEX Physical Research Laboratory in Ahmedabad India, a unit of the Government of India’s Department of Space.  Her work involved analyzing the isotopic composition of calcium- and aluminum-rich inclusions (CAIs) in meteorites via Multi Collector Inductively Coupled Plasma Mass Spectrometry (MC-ICP-MS).

Prajkta’s research in the Center for Meteorite Studies focuses on determining the chemical and isotopic compositions of meteorites in order to shed light on processes in the early Solar System.  She analyzes CAIs to decipher the chronology of early Solar System events and the specific processes involved; CAIs were the first solids to condense from the Solar nebula, and they preserve petrographic and geochemical records of the earliest events to rim photoshape our Solar System.

The inclusions Prajkta studies are encapsulated by distinct edges, composed of only one or two minerals, called Wark-Lovering rims. Due to the extremely small scale of these rims, it is challenging to analyze their chemical and isotopic composition with traditional mass spectrometry techniques. Using the Cameca NanoSIMS 50L at ASU, Prajkta has been able to chemically image Wark-Lovering rims on a nanometer scale via secondary ion mass spectrometry, and has successfully age-dated them using their aluminum and magnesium isotopic content.  The results of her analyses have provided insight into the chronology of events in the early Solar System and the accretion of planetary bodies, and Prajkta plans to continue her study of primitive meteorites to further constrain the formation time of these rims.

In addition to her work on Wark-Lovering rims, Prajkta has measured zirconium isotopes in CAIs, and has investigated the evolution of water reservoirs on Mars using the Prajkta with NANOSimshydrogen isotope composition of the newest martian meteorite fall, Tissint.

Prajkta is a recipient of NASA’s Earth and Space Science Fellowship, and was granted the 2014 Graduate Excellence Award by ASU’s College of Liberal Arts and Sciences.

An active participant in outreach activities, Prajkta frequently represents the Center for Meteorite Studies and School of Earth and Space Exploration at events such as ASU Homecoming, Earth & Space Open House, Night of the Open Door, and Phoenix Comicon.

Having successfully defended her dissertation in September, Prajkta plans to pursue a career in meteoritics and planetary science. She has a strong interest in pioneering analytical methods to significantly advance our knowledge of the building blocks of the Solar System, in particular the development of laboratory techniques to further study the isotope geochemistry of meteorites and samples returned from planetary missions.

Karen Rieck

Karen Rieck received her M.S. from Arizona State University in 2008.  As a Master’s student, she measured lithium isotopes in basaltic meteorites. Supervised by Dr. Richard Hervig, the goal of this research was to better understand the thermal histories of eucrites by measuring chemical heterogeneity within the minerals comprising these basaltic meteorites.

Karen smallDuring her Ph.D. in the School of Earth & Space Exploration, Karen conducted scientific research on Solar System materials under the advisement of her committee members (Richard Hervig, Thomas Sharp, Meenakshi Wadhwa, Peter Williams, Patrick Young, and Amy Jurewicz).

Her primary project centered on quantifying the abundances of sodium and potassium in the solar wind. To do this, she used secondary ion mass spectrometry (SIMS) to measure samples of solar wind returned by NASA's Genesis spacecraft. This information will help to constrain the baseline composition of the protoplanetary disk from which our Solar System formed.  Solar wind samples are a good surrogate for the solar nebula because (1) a preponderance of scientific evidence suggests that the outer layer of the Sun preserves the composition of the early solar nebula, and (2) spacecraft measurements suggest that, for most rock-forming elements, the process of solar wind ejection from the Sun does not appear to cause significant fractionation of elements.

As a secondary project, Karen investigated microtextural changes associated with olivine phase transformation as a function of water content, using optical microscopy, Raman, and scanning electron microscopy, in order to clarify and constrain phase transformation processes in Earth's mantle.

Karen RieckShe also utilized optical microscopy and image processing software to investigate ilmenite abundance & crystal size distribution in Apollo 17 Lunar Samples. The information gleaned from this research will enable better interpretation of remote sensing data from orbiting spacecraft.

Karen is the recipient of three NASA Earth and Space Science Fellowships, awarded to outstanding students pursuing graduate degrees in basic and applied research in Earth and space sciences.

Taking an active interest in geology education and outreach, Karen has served as Secretary, Vice-President, and Outreach Coordinator for the ASU Geology Club.  She has also participated in numerous outreach events with the Center for Meteorite Studies, including the annual Earth & Space Exploration Day, and ASU’s Night of the Open Door.

Having successfully defended her doctoral dissertation in October, 2015, Karen has undertaken a post-doctoral scholarship at Los Alamos National Laboratory, where she will continue analyzing Genesis solar wind samples.

Kera Tucker

Kera Tucker received her B.S. in Geology from Oregon State University in 2011. As an undergraduate student, Kera worked with Dr. Anita Grunder on the geochemical classification of pumices found in Oregon’s Hampton Tuff ignimbrite. The results of this research were presented at the 2011 Geological Society of America’s Rocky Mountain and Cordilleran Joint Meeting in Logan, Utah.

Kera TuckerAfter completing her undergraduate degree, Kera became a Program Specialist with the NASA Astrobiology Institute, and was involved in various education and public outreach efforts including FameLab and NASA Ames team public outreach, as well as social media, and Astrobiology Institute datasets.

Excited to combine her passions for geology and space science, Kera enrolled as a Master’s student in the School of Earth and Space Exploration at ASU in 2013. Her Master’s project was aimed at determining the hydrogen isotopic composition and water content of the interior of Mars by analyzing Nominally Anhydrous Phases (NAPs) in eight martian meteorites. She performed this work under the supervision of Prof. Meenakshi Wadhwa (Director, Center for Meteorite Studies), and in collaboration with Profs. Richard Hervig and Christy Till.

Using the Secondary Ion Mass Spectrometer (SIMS) at Arizona State University, Kera conducted 113 individual analyses of water content and hydrogen isotopic composition of NAPs in the shergottites Zagami, Los Angeles, QUE 94201, SaU 005 and Tissint and in the nakhlites Nakhla, Lafayette, and Yamato 000593. Based on these analyses, Kera was able to infer that the mantle source reservoirs of the martian meteorites were similar to the Earth’s mantle in terms Kera Tuckerof hydrogen isotopic composition and water content.

A portion of Kera's thesis study was recently presented at the 46th Lunar and Planetary Science Conference, in Houston, TX (read Kera's conference abstract here). Having successfully defended her Master’s thesis in April of 2015, Kera will graduate in May.

Kera aspires to a career in field geology, allowing her to pursue her passions for Earth Science and the outdoors, as well as providing the opportunity to inspire and educate future generations.

Graduate Student Spotlight: Daniel Dunlap

Daniel Dunlap received his B. S. from the University of Tennessee in 2013, and is currently enrolled in the second year of his Ph. D. at ASU.  As an undergraduate student, Daniel completed a research project with advisor Hap McSween, which involved the classification of the Tupelo meteorite, an EL6 meteorite from Mississippi.  EL6 chondrites are enstatite chondrites in the low-iron “EL” group, in which all mineral compositions have been homogenized by metamorphism without melting.  The results of Daniel’s research were presented at the 2013 ImageLunar and Planetary Science Conference (read the abstract here).  Daniel remains interested in meteoritics, and is pursuing the use of short-lived chronometers (such as 26Al-26Mg and 53Mn-53Cr) to investigate the timing of planetesimal differentiation in the early Solar System.
Daniel’s current research at the Center for Meteorite Studies is focused on understanding the chronological order of events in the early Solar System.  His main interest is in determining the timing of melting and differentiation on early forming asteroids and planetesimals.  Many of these bodies began forming very early in the Solar System’s history, and were host to igneous processing within as little as a million years or so of Solar System formation.  By placing time constraints on these events, Daniel hopes to better comprehend the formational timeline of the rocky bodies in our Solar System.
To this end, Daniel is utilizing short-lived radionuclides as chronological tools. Some of these short-lived isotopes were only present in the first few million of years of Solar System history, and can be used to constrain relative formation times during this time period with very high precision.  The Mg and Cr isotope systems are of particular importance to Daniel’s research — 26Al decays to 26Mg with a half-life of ~700,000 years and 53Mn decays to 53Cr with a half-life of 3.7 Ma. Due to the potential for terrestrial contamination, the meteorite samples are carefully handled and chemically processed in the ultraclean Isotope Cosmochemistry and Geochronology Meteorite GalleryLaboratory and high-precision isotopic measurements are performed on a Thermo Neptune Multi-Collector Inductively Coupled Mass Spectrometer at ASU.  Most recently, Daniel’s research was presented at the 2014 Lunar and Planetary Science Conference (read the abstract here).
Daniel also takes an active role in outreach events, including Earth & Space Exploration Day, ASU Earth & Space Open House, and ASU’s Night of the Open Door.

Curtis Williams

CurtisCurtis Williams received his B.S. and M.S. degrees in Geological Sciences from Indiana University before enrolling in the Ph.D. program at ASU. As a a student in the School of Earth & Space Exploration, working with CMS Director Wadhwa, Curtis is interested in the formation of our planet and the possibility of forming habitable planets elsewhere. He studies meteorites to infer how our region of the universe progressed through an evolutionary sequence involving the formation and chemical evolution of the galaxy, and gravitational collapse of a molecular cloud, followed by Solar System formation and accretion of planetary-sized bodies. Curtis believes that increased knowledge of the pathways to forming habitable planets is central to our understanding of whether we are alone in the universe.

Curtis’ research focuses on components found within chondritic meteorites that sample various aspects of this evolution. He is currently investigating the chemical and isotopic composition of calcium-aluminum-rich inclusions (CAIs). CAIs are predicted by thermodynamic calculations to be the first phase to condense out of a gas of Solar composition during cooling from high temperatures and, indeed, are extremely old (~4.567 Ga). They exhibit isotopic compositions suggestive of inheriting presolar components from the interstellar medium. Recently, Curtis has developed a technique to measure nucleosynthetic anomalies (as recorded by Ti isotopes) in CAIs by laser ablation multi-collector inductively coupled plasma mass spectrometry (LA-ICPMS). He has employed this technique to measure the Ti isotopic composition of several suites of CAIs. Comparison of these datasets with chemical evolution models of the galaxy show that an additional nucleosynthetic source may be required to explain the initial composition of the Solar System. This is critical knowledge when discussing the ubiquity of forming habitable planets such as Earth.
Curtis Williams field-testing instruments to assist the next generation of astronauts. San Francisco volcanic field, northern Arizona.
Williams has also identified a new FUN CAI (designated CMS-1) that displays Fractionated and Unknown Nuclear effects. CMS-1 has provided remarkable information regarding physical and chemical processes occurring in the early Solar System. In addition to its anomalous Ti isotopic composition, Curtis has shown that CMS-1 formed under nebular conditions (e.g., log fO2 ~10^-19) and, prior to being melted, represents one of the first solids to condense from nebular gas of Solar composition. He has also revealed, through the measurement of mass-dependent fractionation of the relatively volatile elements (Si, Mg and O), that discrete heating events resulting in the evaporation of chondritic components played an important role in chemically differentiating the early Solar System. In the near future, Curtis plans to obtain a uranium isotope-correct Pb-Pb date for CMS-1, which would be the first absolute date determined for any FUN CAI.

Curtis continues to pursue additional constraints on the formation of habitable planets through the analytical and numerical study of the Solar System and its constituent components. He has investigated the chemical composition of Martian meteorites in order to provide key constraints on the origin and evolution of the Martian volatile cycle. He has also used numerical models of mantle convection to better constrain rates of mantle mixing within the Earth and the preservation of mantle heterogeneities over Earth’s history.
Curtis’ long-term career goal is to become a faculty member at a research university. As such, Curtis hopes to advance our understanding of the formation and evolution of habitable planets, and train the next generation of earth and planetary scientists. He also hopes to pursue outreach programs within the local community and, as someone with Native American heritage, to encourage and excite underrepresented groups to become more involved with science, technology, engineering, and math.
In July of 2014, Curtis successfully defended his dissertation and obtained his Ph.D. from Arizona State University's School of Earth & Space Exploration.  Dr. Williams is currently continuing his research as a Postdoctoral Scholar in the Department of Earth & Planetary Sciences, at the University of California, Davis.