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Sebastian Kommescher, Fellowship Grant 2019

Titanium isotope constraints on silicate differentiation and nucleosynthetic heritage of Earth and Moon

The first publication describing a method to investigate Ti isotope variations in terrestrial materials came out in 2014 and the same research group published their first data of terrestrial and lunar samples in a follow-up paper in 2016, right when I started my PhD. Off to a good start, so it seemed. However, we followed a different analytical approach notably high-resolution measurements to account for isobaric interferences. Furthermore, had access to a variety of well-characterized samples to work with. Early 2017, we produced the first set of nucleosynthetic Ti isotope data on lunar samples. However, after a massive brain-drain (i.e. by my then-supervisor leaving), this part of the project was put on ice. Fortunately, Prof. Fonseca then took over as my supervisor and under his guidance, I focused my efforts on the much more promising double spike method. After one more year of method development and refinement as well as a lengthy double-spike calibration and associated setbacks, all was set to tackle the mass-dependent Titanium isotope variations in terrestrial and lunar samples. That is when my funding ran out. At that time, I had already slaved in the Clean Lab facility of Prof. Carsten Münker’s Geo-/Cosmochemistry group for months on end, processed numerous terrestrial and extraterrestrial samples and spent almost every weekend either working in the Lab or measuring the analyte solution on the mass spectrometer. I had most of my data ready, the lunar samples were measured and my first manuscript was about to be written. It is commonly known that PhD projects often require more time than initially anticipated. In science in general, what can go wrong will go wrong and we are all subject to hiatus due to machines breaking down. This is especially true for PhD projects that focus on method development. What is surprising, however, given the frequency of such delays, is that there are remarkably few possibilities for PhD students to acquire additional funding, once they are in the last stage of their PhD. As such, I was all the more grateful when the GSGS announced another phase of fellowship grants. For me, this grant consisted of four months of funding. I am very appreciative of this opportunity, as it allowed me to invest additional time and conduct much-needed work on my manuscript discussing the Ti isotope variations in lunar samples, which was published in February 2020 as an open access paper in Geochemical Perspective Letters https://www.geochemicalperspectivesletters.org/article2007/

Sebastian Kommescher
PhD student
Institute of Geology and Mineralogy
Professor Dr Carsten Münker (working group)
PhD Thesis: “Mass-dependent Titanium isotope variation in terrestrial and extra-terrestrial basalts.” (working title)