Elmar K. Jessberger passed away on November 29, 2017, at the age of 74. Elmar was a Fellow of the Meteoritical Society since 1994. He was organizer of the Society's 66th annual meeting 2003 in Münster. Main Belt asteroid 16231 Jessberger, discovered in 2000, was named after him in 2005. Elmar was born in Eisenach, Germany, on April 18, 1943. He grew up in Hamburg and did his undergraduate studies in Munich and Heidelberg. After finishing a physics diploma in 1969, Elmar received his Ph.D. from Heidelberg University in 1971 with a thesis on mass spectrometric analysis of trapped gases in lunar material, meteorites, and terrestrial basalts. This study was performed with Josef Zähringer and Till Kirsten at the Max Planck Institute for Nuclear Physics in Heidelberg, where Elmar had started working as an undergraduate in 1968 and where he stayed, ultimately as a senior scientist, until 1996. After finishing his Ph.D., Elmar received an NSF fellowship and worked from 1972 to 1973 with Jerry Wasserburg at Caltech, focusing on 40Ar-39Ar dating of lunar samples from the Apollo missions. They found some of the oldest ages ever reported for lunar rocks (Jessberger et al. 1974). During following years, his work in Heidelberg on 40Ar-39Ar dating continued, applying it to impact craters like, e.g., the Nördlinger Ries (Jessberger et al. 1978), the Haughton impact structure (Jessberger 1988; Stephan and Jessberger 1992a), and the Vredefort Dome (Reimold et al. 1992). The response of the K-Ar system to shock events was a recurring theme in Elmar's work, and he stayed involved in dating impact events until recently (Schwarz et al. 2016). 40Ar-39Ar of meteorites was another major subject of Elmar's work; most prominent is his study of the Allende meteorite, where he found, in certain calcium-aluminum-rich inclusions, some apparent 40Ar-39Ar ages that seemed to be older than our solar system, up to 5.1 Ga and even 5.4 Ga in some high-temperature fractions (Jessberger and Dominik 1979; Jessberger et al. 1980). Elmar never claimed that these samples were presolar or that these apparent ages had any chronological significance, since he was aware of the peculiarities of the 40Ar-39Ar dating technique that could lead to incorrect ages (Jessberger 1984). However, to this date, these apparent ages remain enigmatic and could not be fully explained by experimental artifacts. Other 40Ar-39Ar studies of meteorites Elmar was involved in focused predominantly on ordinary chondrites (Stephan and Jessberger 1988, 1992b; Kunz et al. 1997; Trieloff et al. 2003; Korochantseva et al. 2007). While Elmar's early work was mostly related to 40Ar-39Ar dating, a field that was always very close to his heart and also became the subject of his habilitation thesis (Jessberger 1982), he eventually joined Hugo Fechtig's dust group at the Max Planck Institute for Nuclear Physics. He became heavily involved in the evaluation and interpretation of the data from the impactionization mass spectrometers onboard the Vega 1 & 2 and Giotto space probes measuring the dust composition during the flyby at comet 1P/Halley in 1986 (Jessberger et al. 1988, 1989; Jessberger and Kissel 1991). Parallel to his work on the Halley data, he used proton-induced X-ray spectroscopy (PIXE) and synchrotron X-ray fluorescence (SXRF) to study elemental abundances in interplanetary dust particles (IDPs; Jessberger and Wallenwein 1986; Arndt et al. 1996; Wies et al. 2001). During his involvement in further space experiments, which ultimately led to the COSIMA instrument for the European Rosetta mission to comet 67P/Churyumov–Gerasimenko (Kissel et al. 2007; Hilchenbach et al. 2016), Elmar promoted establishing time-of-flight secondary ion mass spectrometry (TOF-SIMS) as a new technique in cosmochemistry. His credo always was that sample analysis in space has to be complemented by state-of-the-art laboratory analysis here on Earth, and he promoted multitechnique analyses of samples like IDPs as an approach complementary to space missions (Jessberger et al. 2001). In 1996, Elmar became full professor of Analytical and Experimental Planetology at the Institute for Planetology at the University of Münster. During his time in Münster, he established a dedicated TOF-SIMS laboratory to analyze all kind of extraterrestrial samples like, e.g., IDPs (Stephan et al. 1994; Rost et al. 1999), meteorites (Semenenko et al. 2005; Morlok et al. 2006), including those from Mars (Stephan et al. 2003; Rost et al. 2009), and presolar grains (Henkel et al. 2007). This TOF-SIMS laboratory eventually played a significant role in the analysis of cometary samples returned by the Stardust mission. Toward the end of his professional career, Elmar became more involved in space experiments (Mann and Jessberger 2003) and even remote astronomical measurements (Kimura et al. 2003), without giving up his connection to laboratory measurements (e.g., Meierhenrich et al. 2004). Elmar was one of the initiators of the Mercury Radiometer and Thermal Infrared Spectrometer (MERTIS) for the BepiColombo mission (Arnold et al. 2008) and promoted GENTNER, a combined laser-induced breakdown spectroscopy (LIBS) and Raman spectroscopy instrument, for the ExoMars mission (Rauschenbach et al. 2010; Weber et al. 2017). Elmar served on numerous scientific committees, e.g., as chairman of the Leonard medal committee of the Meteoritical Society; as senior scientific advisor of the Space Science Committee of the European Science Foundation; as a member of various commissions of the Max Planck Society, most notably as a member of the Max Planck Committee for the Advancement of Female Scientists; as a member of various committees of the German Aerospace Center (DLR); and many more. Elmar had a lot of friends in science all over the world. As a guest scientist, he visited the State University of New York in Stony Brook in 1981 and the McDonnell Center for the Space Sciences, Washington University in Saint Louis in 1984. From 1991 to 1992, he spent a sabbatical at the University of Vienna and the Natural History Museum in Vienna. After his retirement in 2008, Elmar stayed involved in science, mainly as an advisor in some of the projects he initiated. He was especially pleased to see his scientific legacy live on in the work of his numerous former students. Elmar constantly promoted the careers of his students and enabled them to become successful scientists. We, who had the privilege to work closely with Elmar, will miss him as a great mentor and very good friend. We will especially miss the endless discussions, which usually involved a lot of cigarette smoke and a glass of wine (or two), about science, life, and everything. Toward the end of his fulfilled life, Elmar became a devoted family man, who took the greatest pleasure in spending time with his five grandchildren Jonathan, Luise, Lotte, Stella, and Jil. Elmar is survived by his wife Ulrike, their sons Florian and Sebastian, and their families.