Comets are balls of rock and ice that preserve a chemical record of the early solar system, and researchers will analyse microscopic grains of cometary dust to read that record. Despite decades of study, scientists still do not know what comets are made of or how much variation exists among them. Only nine comets have been visited by space missions, and those were brief flybys with limited instruments. Telescopes struggle because comets’ surfaces are altered by space weathering and obscured by their own gas and dust. This project fills that gap by using high-precision laboratory instruments—infrared and Raman spectroscopy, scanning electron microscopy, and NanoSIMS—to measure the chemical and isotopic composition of cosmic dust collected on Earth. These are the same techniques used to study meteorites, allowing direct comparison. This is fundamental science with no immediate practical application. Understanding what comets are made of and how they vary tells us how the outer solar system formed, how planetary precursors assembled, and how water and other volatiles arrived on Earth. Similar fundamental work on meteorites has reshaped our understanding of planet formation; this project extends that knowledge to the outer reaches of the protoplanetary disk.
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Project highlights: Work directly with extraterrestrial material (cometary dust). Develop a transferrable skillset in the independent use of high-precision microanalysis instrumentation (IR and Raman spectroscopy, SEM and NanoSIMS, with an option to develop into nanoscale TEM work later into the project). Primary research question: What are comets made of, and how diverse are they? Investigate the chemical and isotopic composition of the early outer solar system, constraining physio-chemical processes that operated in the protoplanetary disk. Comparison against existing data from meteorites, advancing our understanding of solar system evolution. Project description Comets are balls of rock and ice that formed in the outer regions of the early solar system. Their primitive compositions preserve insights into the reservoirs from which matter condensed, the accretion behaviour of solids at large heliocentric distances and the origin of water and other volatiles. Today, comets originate from two source regions - an inner ring extending from the orbit of Neptune out to ~1000 AU (the Kuiper Belt) and an outer spherical zone >10,000 AU from the Sun (the Oort Cloud). Despite decades of research we still know little about the composition and internal structure of comets nor do we know how much variation exists among the comet population. Are there different compositional types of comets and if so, what can these types tell us about the structure of the protoplanetary disk? Comets are difficult to study and remain poorly characterised. Space missions have visited just nine comets, eight of which were single-pass flybys carrying limited instrumentation. Analysis of cometary dust from the coma of WILD 2 was hindered by the high-speed (~6 km s-1) capture technique employed while telescope observations are impeded by coma activity, space weathering altering the comet's surface and, for ground-based instruments, observational constraints imposed by Earth's atmosphere. However, new opportunities are emerging through the microanalysis of cosmic dust (derived from comets and collected on Earth) with huge potential to complement remote study and drive major discoveries. Only laboratory analysis can provide the high fidelity isotopic and chemical data needed to accurately characterise the primitive building blocks of the outer Solar System and investigate their natural variability. This will help us to understand the formation of planetary precursors and exoplanetary systems.
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