Leafia Sheraden Cox

Years participated in RESESS: 2019


An Overview

Major: Geoscience, Astronomy (minor)

Academic Affiliation: Wellesley College


Leafia Sheraden Cox is a rising senior undergraduate student at Wellesley College. She is currently pursuing a bachelor’s degree in Geoscience with a focus on planetary science and minoring in Astronomy. This summer, she worked at the Southwest Research Institute in Boulder and built a handheld fluorescent spectrometer for mineral analysis in the field using consumer-off-the-shelf products. Her interests include instrumentation, planetary analog environments, fieldwork, and scientific outreach.


Design and Potential of a Compact Low-Cost Reflectance Spectrometer and Fluorimeter

The development of instruments and analytical techniques for use in crewed extraterrestrial missions is crucial for the advancement of human space exploration. Determining the general composition of a sample site in-situ is important for conserving mission resources, managing extra-vehicular activity time, and maintaining operational efficiency. Active spectroscopy is a common method of in-field analysis of samples; however, current instruments are expensive, large, and complex. A combination of visible reflectance and fluorescence spectroscopy can deliver bulk mineralogical composition measurements that are useful in selection and analysis of sample sites. As a part of NASA’s Solar System Exploration Research Virtual Institute’s Project for Exploration Science Pathfinder Research for Enhancing Solar System Observations (Project ESPRESSO) node, we developed a hand-held reflectance spectrometer and fluorimeter for in-field sample analysis. The instrument was constructed using consumer off-the-shelf products and was designed to be field-portable, low-cost, extremely compact, and simple to build and operate while allowing responsive, in-field adjustments to both data-collection and data-analysis. Samples are illuminated by three light sources: a 278 nm UV-C LED, a 365 nm UV-A LED, and an LED white light source. Reflectance and fluorescence were measured in 18 wavelength bands from 410 nm – 940 nm, with FWHM of 20 nm. Samples from 34 mineral classes were provided by the Denver Museum of Nature and Science to be measured and compiled as a reference library of characteristic spectra. A case study was conducted at the Palisades Sill, a lunar analog site, in Fort Lee, NJ. Measurements of samples along several transects were taken in-field and analyzed for bulk composition of selected end-member minerals: Albite, Augite, Magnetite and Olivine. A chi-square minimization model was implemented to estimate the fractional area occupied by each mineral in any given sample. We present the results of the case study and the compiled mineral spectral library as a preliminary analysis of the instrument’s capabilities and discuss its further development and potential, including for lunar exploration.