Nicolle Zellner | Albion College (original) (raw)

Papers by Nicolle Zellner

ABSTRACT Lunar impact glasses from the Apollo 15 landing site provide information about the rate ... more ABSTRACT Lunar impact glasses from the Apollo 15 landing site provide information about the rate of impacts in the Earth-Moon system. Geochemical and age data, in the context of the landing site and in concert with other lunar data, will be presented.

Bulletin of the AAS, 2021

Introduction: Lunar i mpact glasses possess the unmodified refractory element ratios of the origi... more Introduction: Lunar i mpact glasses possess the unmodified refractory element ratios of the original fused target materials at the sites of impacts. These target materials are usually regolith. 778 glasses from the Apollo 14 landing site have been analyzed by electron microprobe in this study. These glasses show significant variation and hint at the existence of multiple terrains of differing compositions near the landing site. Clementine color image data have been used to construct iron, titanium, and aluminum maps for comparison with the sample database. These maps suggest that the highlands in the Fra Mauro region of the Moon consist of a KREEP-rich regolith overlying a more feldspathic terrain. These results illustrate how lunar impact glasses and orbital data can provide geochemical constraints on the local and regional geology of the Moon [1,2]. Lunar Impact Glasses: Lunar impact glasses are droplets of melt produced by energetic cratering events that were quenched during ballistic flight. They possess the refractory element ratios of the original fused target materials at the site of impact [3]. Impact glasses offer the potential for providing information about local and regional units and terrains. Although glass compositions have been interpreted as having rock comp ositions, based on rock types at the collection sites [4,5], this study uses orbital data to show that glass comp osition(s) most often represent regolith composition(s). The Apollo 14 Landing Site: Apollo 14 was sent to sample the Fra Mauro Formation, which is interpreted to be dominated by Imbrium ejecta. Ridges of the Fra Mauro Formation are roughly radial to the Imbrium Basin and were probably formed by material flowing along the ground during excavation of the basin [6,7]. Cone Crater, which is on top of one of the ridges, may have penetrated the KREEP-rich regolith into an underlying, more feldspathic terrain [2,6]. Although orbital data [1,2,8] show that the surface of the Apollo 14 region is KREEP-rich, several outcrops of feldspathic material are seen on crater rims [2]. Sample Analysis: 151 impact glasses from Apollo 14 regolith 14259 have been analyzed by electron microprobe for the elements Si,

arXiv: Instrumentation and Methods for Astrophysics, 2019

The Committee on the Status of Women in Astronomy (CSWA) is calling on federal science funding ag... more The Committee on the Status of Women in Astronomy (CSWA) is calling on federal science funding agencies, in their role as the largest sources of funding for astronomy in the United States, to take actions that will advance career development and improve workplace conditions for women and minorities in astronomy. Funding agencies can and should lead the charge to produce excellent diversity and inclusion outcomes in our field by the 2030 Astrophysics Decadal Survey. Anecdotal and quantitative evidence, gathered both by the CSWA and other groups, shows that many structural barriers to success remain in our community. We acknowledge the success of programs like NSF-INCLUDES and NSF-ADVANCE and endorse their continued work. We also recommend further action to remove barriers to success for women and minority astronomers. Key recommendations are: - Federal agencies should push academic institutions to reconsider their support systems for scientists by requiring a high standard of pay and...

Bulletin of the AAS, 2021

Major advances in planetary science will be driven by determining absolute ages of geologic units... more Major advances in planetary science will be driven by determining absolute ages of geologic units on multiple bodies in the inner Solar System in the next decade. Absolute ages calibrate bodyspecific chronologies and create a framework for understanding Solar System formation, the effects of impact bombardment on life, and the evolution of planets and their interiors. We recommend that the Decadal Survey: • Support Mars Sample Return to ensure the return to Earth of a set of carefully-chosen, well-documented samples for geochronology and other critical studies of Mars' evolution and past habitability. • Prioritize sample-return missions from planetary bodies in the inner Solar System that would answer fundamental questions about the timing of major events in planetary history. • Advocate for sustained funding for in situ dating instruments to continue to raise their technology readiness levels for future exploration of planetary surfaces. • Include a Solar System chronology mission on the New Frontiers mission list, setting the science goals of such a mission but allowing flexibility in how those goals are accomplished. • Reemphasize the importance of an investment strategy for laboratory instrumentation and curation sufficient to provide for both replacement of existing capacity and development of new capabilities. • Recommend that NASA partner with NSF on their Decadal geochronology initiative to leverage NASA's investments in infrastructure supporting planetary geochronology.

Bulletin of the AAS, 2021

This white paper is submitted as part of a collaborative effort organized by the Equity, Diversit... more This white paper is submitted as part of a collaborative effort organized by the Equity, Diversity, and Inclusion Working Group (EDIWG), a cross Assessment Group (AG) committee. Signatory list (55+): Google spreadsheet Synopsis + Recommendations Planetary Science and Astrobiology need more than numerical diversity to create and sustain a thriving scientific discipline and community; they also need scientists from a variety of backgrounds and institutions. Support is particularly needed for caregivers, people who breastfeed, people who work at Primarily Undergraduate Institutions (PUIs) and Minority Serving Institutions (MSIs), and people who choose career paths that do not include research at large universities or NASA centers. By providing supportive work and conference environments, as well as opportunities for scientists to develop skills and collaborations that will further their careers, the fields of Planetary Science and Astrobiology will become more just and equitable. Retaining people with diverse backgrounds, perspectives, home situations, and employment institutions supports our community and improves the science that is done, leading to new ideas and more creative problem solving (e.g., [1]). We make the following recommendations: • Coordinate professional development efforts with those identified by the Astronomy and Astrophysics communities (i.e., Astro2020 recommendations); • Initiate funding and support for faculty/researchers in nontraditional paths, including caregivers; faculty at PUIs and MSIs; scientists on non-research career paths; and grantsupported researchers. • Provide additional support for professional development (e.g., proposal writing and review, manuscript review, classroom management); and • Establish programs that partner faculty at PUIs and MSIs with researchers at larger institutions or NASA centers or with postdocs who seek careers in teaching.

Bulletin of the AAS, 2021

Geosciences, 2019

Determining the impact chronology of the Moon is an important yet challenging problem in planetar... more Determining the impact chronology of the Moon is an important yet challenging problem in planetary science even after decades of lunar samples and other analyses. In addition to crater counting statistics, orbital data, and dynamical models, well-constrained lunar sample ages are critical for proper interpretation of the Moon’s impact chronology. To understand which properties of lunar impact glasses yield well-constrained ages, we evaluated the compositions and sizes of 119 Apollo 14, 15, 16, and 17 impact glass samples whose compositions and 40Ar/39Ar ages have already been published, and we present new data on 43 others. These additional data support previous findings that the composition and size of the glass are good indicators of the quality of the age plateau derived for each sample. We have further constrained those findings: Glasses of ≥200 μm with a fraction of non-bridging oxygens (X(NBO)) of ≥0.23 and a K2O (wt%) of ≥0.07 are prime candidates for argon analyses and more ...

Journal of Astronomy & Earth Sciences Education (JAESE), 2018

An introductory Astronomy survey course is often taken to satisfy a college graduation requiremen... more An introductory Astronomy survey course is often taken to satisfy a college graduation requirement for non-science majors at colleges around the United States. In this course, material that can be broadly categorized into topics related to “the sky”, “the Solar System”, “the Galaxy”, and “cosmology” is discussed. Even with the wide variety of topics in these categories, though, students may not be 100% interested in the course content, and it is almost certain that a specific topic about which a student wishes to learn is not covered. To at least partly address these issues, to appeal to all of the students in this class, and to allow students to explore topics of their choice, a video project has been assigned to students at Albion College as a class activity. In this assignment, students are asked to create a video of a famous (or not) astronomer, astronomical object or discovery, or telescope observatory to present to the class. Students work in pairs to create a video that is or...

European Journal of Physics, 2016

Albion College, a private, undergraduate-only, liberal arts college in Michigan, USA, has develop... more Albion College, a private, undergraduate-only, liberal arts college in Michigan, USA, has developed and implemented a low-cost peer-mentoring program that blends personal and academic support to help students achieve academic success in the introductory courses required for the Physics Major or the Dual-Degree Program in Engineering. This enhanced mentoring program provides much-needed assistance for undergraduate students to master introductory physics and mathematics coursework, to normalize the struggle of learning hard material, and to accept their identity as physics or engineering students (among other goals). Importantly, this program has increased retention among entering science, technology, engineering and mathematics students at Albion College as they move through the introductory classes, as shown by a 20% increase in retention from first-semester to third-semester physics courses compared to years when this program was not in place.

Introduction: Impact events have played an important role in the evolution of planets and small b... more Introduction: Impact events have played an important role in the evolution of planets and small bodies in the Solar System. Meteorites, lunar melt rocks, and lunar impact glasses provide important information about the geology of the parent body and the age of the impacting episodes. Over 2400 impact glasses from 4 Apollo regolith samples have been geochemically analyzed and a subset has been dated by the 40 Ar/ 39 Ar method. New results, consistent with 2 break-ups in the Asteroid Belt, are presented here. Our previous study [1] reported that 40 Ar/ 39 Ar ages from 9 impact glasses showed that the Moon experienced significant impacts at ~800 Ma and at ~3800 Ma ago, somewhere in the vicinity of the Apollo 16 landing site. Additionally, [2] reported on Apollo 12 samples with ages around 800 Ma, together implying global bombardment events. New data on 7 glasses from regolith sample 66041,127 show that the Moon also experienced impact events at ~300 Ma and >500 Ma ago, which may coincide with the break-ups in the Asteroid Belt of the Land H-chrondrite parent bodies [e.g. 3,4]. Since meteoritic evidence for these breakups has been found on Earth, it follows that evidence should be found in lunar samples as well. Lunar Impact Glasses: Lunar impact glasses are droplets of melt produced by energetic impact events that were quenched during ballistic flight. They possess the refractory element ratios of the original fused target materials at the site of impact [5].

Introduction: Lunar impact glasses are droplets of melt, produced by energetic impact events, whi... more Introduction: Lunar impact glasses are droplets of melt, produced by energetic impact events, which were quenched during ballistic flight. They possess the refractory element ratios of the original fused target materials at the site of impact [1]. Lunar impact glasses offer the potential not only for providing compositional information about local and remote areas of the Moon [1,2,3] but also for placing constraints on the impact history in the Earth-Moon system. Impact events have contributed to the crustal and environmental histories of planets. Previous workers have reported 40 Ar/ 39 Ar ages of ~800 Ma on lunar samples from Apollo 12 [rock fragments; 4], Apollo 14 [impact glasses; 5], and Apollo 16 [impact glasses; 6,7]. This abstract presents additional 40 Ar/ 39 Ar ages on impact glasses from the Apollo 14 and 17 landing sites. When all of these data are viewed collectively, there is a suggestion that there may have been a transient increase in the impact flux at ~800 Ma. If correct, this increased bombardment should be kept in mind when interpreting the phylogenetic history of life on Earth during the Neoproterozoic era [8].

Introduction: Understanding the lunar impact flux has been identified as one of NASA's top priori... more Introduction: Understanding the lunar impact flux has been identified as one of NASA's top priorities, and a variety of lunar samples are being studied to address this issue. These samples include lunar impact glasses [e.g., 1, 2, 3], lunar melt rocks [e.g., 4, 5, 6], lunar meteorites [e.g., 7], and lunar zircons [e.g., 8]. In particular, these samples are being used to address whether or not the Moon experienced a late heavy bombardment or terminal lunar cataclysm between 3.8 and 3.9 billion years ago (Ga) [e.g., 9]. However, they can also give us insight into the nature and timing of impact events throughout the age of the Solar System [e.g., 1, 3, 15]. Care must be taken, though, to completely examine the samples and to appropriately interpret the data so that the impact flux is neither overinflated nor underreported. Here we describe the nature of the reported increase in lunar impact flux over the last ~500 Ma [3, 11]. Lunar Glass Studies: In this investigation, we have looked at the lunar impact glass data, including unpublished data, from the Apollo 14, 16, and 17 landing sites [1, 2, 10] and published data from the Apollo 12 landing site [3]. Glass spherules and fragments analyzed by [1, 2, 10] were geochemically analyzed by electron microprobe and laser step-heated at the University of Arizona noble gas lab to obtain 39 Ar/ 40 Ar ages on each sample. Uncertainties in the geochemical measurements were usually <3% of the amount present, and the precision of the 39 Ar/ 40 Ar ages was limited by the [K], size, and age of the sample. Glass spherules analyzed by [3] were geochemically analyzed by energy dispersive spectroscopy (EDS) and similarly dated at the Berkeley Geochronology Center. In their EDS analyses, only spot measurements on the surfaces of the spherules were obtained, with non-ideal geometries causing an estimated 10% error in the composition. The more precise K/Ca ratio was inferred from the measured 39 Ar/ 37 Ar ratio. Using the ages of the 81 impact glasses from the Apollo 12 landing site, [3] reported

We have obtained the first ultraviolet linear spectropolarimetry of Mars using the Wisconsin Ultr... more We have obtained the first ultraviolet linear spectropolarimetry of Mars using the Wisconsin Ultraviolet PhotoPolarimetry Experiment (WUPPE), which flew on the Astro-2 shuttle mission. Mars was observed on March 12, 1995 at a phase angle of 21 degrees. A ground-based support observation was taken within 24 hours at the Pine Bluff Observatory (PBO), providing a total spectral coverage of 2000

Bulletin of the AAS, 2021

arXiv: Instrumentation and Methods for Astrophysics, 2019

Bulletin of the AAS, 2021

Geosciences, 2019

Journal of Astronomy & Earth Sciences Education (JAESE), 2018

European Journal of Physics, 2016