Sierra is a PhD candidate in ASU's School of Earth and Space Exploration working with Professor Steve Desch and Dr. Alyssa Rhoden. Her research focuses on understanding the history of Saturn's mid-sized moons with a focus on Tethys, Dione, and Rhea. The work she does utilizes data from the Cassini spacecraft to create maps of the surfaces of these moons. Recently, she has mapped the impact craters on Dione and found that their likely impactor source would be from Saturn-orbiting debris. When examining the azimuths of elliptical craters on Dione, she and her co-authors found no variation across hemispheres, whereas the same crater morphology on Tethys exhibits variation in azimuth values across the leading and trailing hemispheres. This result implies a similar impactor population creating the elliptical craters on Dione, whereas these craters on Tethys may have been formed by several different sources. An overarching goal of her research is to aid in the determination of the ages of the mid-sized Saturnian satellites. Read Sierra's LPSC abstract here.
Jack is a 2nd year undergraduate student studying Physics with a minor in Astrophysics. He is working with Dr. Maitrayee Bose in the Center for Isotope Analysis, researching presolar grains. His work focuses on using new and realistic three-dimensional supernova models to constrain the origins of silicon carbide (SiC) and silicon nitride grains. He intends to use isotopes of light and heavy elements to understand the nucleosynthesis occurring in supernova ejecta, with the eventual goal being to expand our understanding of the nature of supernova that seeded the solar nebula. At LPSC, he presented the results of his analysis of four supernova models, one symmetric and three asymmetric. He showed that two of the asymmetric models worked best to explain the C, N, Si, Al, Fe and Ni isotopic compositions of SiC grains. Read Jack's LPSC abstract here.
Daniel is a 5th year PhD candidate studying under Professor Meenakshi Wadhwa in the Isotope Cosmochemistry and Geochronology Lab at ASU. He uses both short-lived (Al-Mg and Mn-Cr) and long-lived (Pb-Pb) isotope systems to determine high precision ages of achondrites; achondrites are meteorites that have experienced varying degrees of heating which took place in the earliest epoch of Solar System history. His work specifically focuses on the ungrouped and underrepresented achondrites. By studying these achondrites, he hopes to expand our understanding of the timeline of igneous activity in the early Solar System. Read Daniel's LPSC abstract here.
Sierra is a Ph.D. student in ASU’s School of Earth and Space Exploration, working with Professor Alyssa Rhoden. Her research currently focuses on the mid-sized moons of the Saturnian system, with a focus on Tethys, Rhea, and Dione. The investigations that she is conducting on these moons involve the tectonic structures, craters, and other surface features of the moons. She utilizes ArcGIS for the mapping of these surface features on mosaics that she created from the raw Cassini image data. An overarching goal of her research is to analyze the bombardment history of Saturn’s moons to aid in the determination of the ages of the mid-sized Saturnian satellites. Read Sierra's LPSC abstract here.
Alexandra recently completed her M.S. studies with Professor Steve Desch in the ASU School of Earth and Space Exploration. Her research involves investigating the validity of the planetary embryo bow shock model by conducting dynamic crystallization experiments. Her results show that the most dominant chondrule texture, porphyritic, requires cooling rates < 1000 K/hr to form. The planetary embryo bow shock model therefore is a viable chondrule mechanism for the formation of most chondrules, although lower cooling rates would be preferred. Cooling rates in the bow shock model are inversely proportional to planet size, suggesting that the bow shock around a planetary embryo larger than Mars may better produce porphyritic textures. These results imply that large planetary embryos were present and on eccentric orbits during the first few million years of the Solar System’s history. Read Alexandra's LPSC abstract here.
Zack is a Ph.D. candidate in the Center for Meteorite Studies, studying under Professor Meenakshi Wadhwa. He studies calcium-aluminum-rich inclusions (CAIs), which were the first solids formed in the early Solar System and thus preserve a record of the earliest processes and conditions in the solar nebula. At LPSC, he presented high-precision Cr, Ti, and Mg isotope measurements of a suite of CAIs that were analyzed on the Neptune MC-ICP-MS in ASU’s Isotope Cosmochemistry and Geochronology Laboratory. These samples showed resolvable mass-independent anomalies in both Ti and Cr isotopes, suggesting significant isotopic heterogeneity in the broader CAI-forming region in the protoplanetary disk. The "bulk" Al-Mg isochron yields a canonical 26Al/27Al value, consistent with homogeneous distribution of 26Al in the solar nebula. Read Zack's LPSC abstract here.
Emilie is a Ph.D. candidate in the Center for Meteorite Studies, studying under Professor Meenakshi Wadhwa. She analyzes the oldest Solar System rocks (calcium-aluminum-rich inclusions) in order to learn about the violent environment in which they were formed. Specifically, she utilizes mass spectrometry techniques to infer the abundances of elements which only existed in the early Solar System; these analyses provide insight into events that occurred more than 4.56 billion years ago, such as irradiation processes, where high-energy particles collide with nebular gas to produce new elements. Emilie is also advised by Dr. Steven Desch on a secondary project, with the goal of understanding the composition of the Kuiper Belt Object (KBO) Haumea. This KBO likely suffered a large collision which influenced its shape (it is football shaped), and Emilie's research indicates that Haumea has a hydrated silicate/clay core surrounded by a thin (~10km) icy shell. This composition hints that Haumea could have been habitable in the past! Read Emilie's abstracts here, and here!
Crystyl is a Ph.D. candidate studying shocked meteorites to understand impact conditions on planetary bodies, under the mentorship of advisor Dr. Thomas Sharp. In her research, she uses a combination of optical microscopy, scanning electron microscopy and electron probe microanalysis to investigate transformation and recrystallization textures, and Raman spectroscopy to identify high-pressure mineral assemblages. At LPSC, she presented results on a eucrite containing a range of shock-induced effects, including high-pressure polymorphs of silica and feldspar. Her future work will include further characterization of shock features in HED meteorites and constraining shock pressure-temperature conditions to understand impacts on the asteroid 4 Vesta. Read Crystyl's abstract here!
Viranga is a Ph.D candidate working with Professor Erik Asphaug. His research areas include the thermal evolution of the Moon, interior structures of asteroids, and the link between the affective domain and online science education. At LPSC, he presented work showing that, due to re-impacting debris, the magma ocean of the Moon likely cooled faster than is currently considered. Read Viranga's abstract here!
Zack is a Ph.D. candidate in the Center for Meteorite Studies, studying under Professor Meenakshi Wadhwa. He studies calcium-aluminum-rich inclusions (CAIs), which were the first solids formed in the early Solar System and, thus, preserve a record of the earliest processes and conditions in the solar nebula. At LPSC, he presented high-precision Ti and Cr isotope measurements from a new suite of CAIs that were analyzed on the Neptune MC-ICP-MS in ASU’s Isotope Cosmochemistry and Geochronology Laboratory. These samples show resolvable variations in mass-independent anomalies in both Ti and Cr isotopes, suggesting significant isotopic heterogeneity in the broader CAI-forming region in the protoplanetary disk. His future work will seek to expand this sample set and characterize the nature of this heterogeneity. Read Zack's abstract here!
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.
Emilie is currently in the second year of her Ph.D., studying in the Center for Meteorite, under Professor Meenakshi Wadhwa. Her research focuses on determining the chemical and isotopic composition of meteorite components, to better understand the astrophysical birthplace of our Solar System. She analyzes Calcium Aluminum-rich Inclusions (CAIs); as the first solids to condense from the solar nebula, they recorded the earliest events that shaped the Solar System. Specifically, she is measuring the concentration of 10Be in CAIs using ASU's SIMS (Secondary Ion Mass Spectrometer) in order to tell the story of its formation.
Simulating haze particles in a H2-rich exoplanet atmosphere with high temperature discharge experiments.
Ehsan received his M.S. in physical chemistry from the University of Tehran at Iran, in 2013. His thesis focussed on the spectroscopy of diatomic molecules of astrophysical interest. Upon completion of his master's degree, his enthusiasm for astrochemistry lead him to apply to ASU, where he is currently working toward his Ph.D. under the supervision of Professor James Lyons, in the School of Earth and Space Exploration. To date, his studies have included the determination of oxygen isotope ratios in the solar photosphere (using the observationed CO infrared spectrum), as well as laboratory simulation of haze/aerosol formation in exoplanet atmospheres. While these projects may, initially, seem quite different from each other, they share the common goal of improving our understanding and interpretation of observed astronomical spectra.
Exploring non-uniform 40Ar* loss in Apollo 16 impact melt breccias using a laser microprobe.
At LPSC, Cameron presented 139 new spot fusion 40Ar/39Ar dates for three samples from the Apollo 16 sample archive. Published incremental heating 40Ar/39Ar data for two of these samples exhibit low apparent ages at low experimental temperatures, and higher apparent ages at intermediate to high experimental temperatures. These release spectra were interpreted to indicate that the samples had experienced partial loss of radiogenic 40Ar (denoted 40Ar*) following their formation, due to one or more reheating events. The laser microprobe is a useful tool for exploring the spatial variability of argon loss in such samples while preserving the petrographic context of the dated materials. Combined with ongoing work, the laser microprobe 40Ar/39Ar data will help to constrain the thermal histories recorded by these samples. Cameron is a Ph.D. candidate in the School of Earth & Space Exploration, studying under Professor Kip Hodges.
Order from chaos: A quantitative approach to identifying small chaos features on Europa.
Jessica Noviello is a second year Ph.D. student in the School of Earth & Space Exploration, studying under Professor Alyssa Rhoden. Her LPSC presentation explored the color data taken of Europa during the Galileo mission, in order to classify small chaos patches. Chaos usually presents as redder than the surrounding terrain and other small-scale features such as pits, spots, and domes. The red color is believed to be evidence of salts on Europa’s surface, and implies that liquid water exists at, or near, the surface around chaos patches. Combining the color data with other observational characteristics could enable the identification of small patches of chaos in low-resolution (> 1 km/pixel) images of Europa, yielding more data on the global frequency of chaos patches. This new information would help constrain heat-flux models of chaos model formation and make testable predictions for the upcoming Europa Flyby Flagship mission. Knowing how chaos forms could indicate where liquid water is most likely to be located, and guide the search for extraterrestrial life on Europa.