Understanding our solar system history through in situ nanoscale analysis of extraterrestrial materials: A special issue for Dr. Christine Floss

This special issue is dedicated to the memory of Dr. Christine Floss (Fig. 1). Dr. Floss (1961–2018) was a Research Professor in the Department of Physics and McDonnell Center for Space Sciences at Washington University in St. Louis (WUSTL). Christine was a longtime member and a fellow of the Meteoritical Society and served as an associate editor for Meteoritics & Planetary Science for 10 years (2005–2015). For over 30 years, Dr. Christine Floss measured the isotopic and elemental compositions of macroscopic to submicroscopic components in extraterrestrial materials to better understand their origins and processes, for example, planetary differentiation, thermal metamorphism, and aqueous alteration, during the early history of our solar system. In particular, she was an expert in the trace element and isotopic analysis of planetary materials, meteorites, and stardust (“presolar”) grains, studying the origin and evolution of the solar system. For her research, she used coordinated in situ ion microprobe (Cameca IMS-3f and NanoSIMS 50) and electron microscopy (SEM, Auger Nanoprobe, and dual-beam FIB-TEM) techniques. Christine’s research interests were extremely diverse, and she studied many different types of extraterrestrial materials, from lunar samples to meteorites and presolar grains, returned samples from the NASA Stardust and Genesis missions, Antarctic micrometeorites (AMMs), and interplanetary dust particles (IDPs). She was involved in the chemical and isotopic studies of IDPs, AMMs, and primitive chondrites to understand the origins of presolar and protosolar components in these materials. She performed evaporation experiments to better understand the origin of calcium-aluminum-rich inclusions and isotopic and compositional studies of Stardust crater residues and hypervelocity impact experiments to characterize the samples returned from comet 81P/Wild 2. Identification and characterization of craters from the Stardust interstellar dust collector also attracted her scientific interest. She also studied the trace element distribution of individual minerals in extraterrestrial samples, to understand their petrogenesis, as well as secondary effects occurring on their parent bodies (thermal metamorphism, aqueous alteration). Christine was a gifted and dedicated scientist and mentor, and an extraordinary colleague, collaborator, and friend to many in the cosmochemistry and planetary science community. This issue presents research by her former students, friends, and collaborators. Christine’s former collaborators Dr. Alexander Ruzicka and Dr. Larry Nittler served as associate and guest editors for this MAPS issue. Christine earned a B.A. in German from Purdue University in 1983; a second degree in Geology from Indiana University, Bloomington in 1987; and a PhD in Geochemistry from the Department of Earth and Planetary Sciences at WUSTL in 1991. Her bachelor’s work at Indiana University focused on the compositions of glass fragments in Apollo 16 regolith breccias. During her PhD, Christine worked with Dr. Ghislaine Crozaz on rare Earth element (REE) distributions in meteorites (e.g., aubrites) and ferroan anorthosites. She showed that the heterogeneous REE patterns in oldhamite from aubrites can be best understood by their condensation in the solar nebula, contrary to popular theories about their igneous origins in a parent body. It was during her time at WUSTL that she developed her expertise with—and love of—the ion microprobe as her instrument of choice to explore the characteristics and origins of extraterrestrial materials. Christine moved to Heidelberg, Germany, in 1991 after completing her doctorate for a research scientist position at the MaxPlanck-Institut f€ ur Kernphysik. She got married in 1993 in Heidelberg to the late Dr. Frank Stadermann. While at the Max-Planck-Institut f€ ur Kernphysik, Christine published on aubrites, angrites, and pallasites, showing early on the breadth of her interests and developing expertise with microanalysis, especially with Meteoritics & Planetary Science 55, Nr 6, 1153–1159 (2020) doi: 10.1111/maps.13489