Studies on Planetary Formation and Evolution at Bristol

The proposed work follows the development of planetary bodies from formation of their raw materials to the functioning of their atmospheres. Our attention starts with the earliest solar system, when the only fine grained material was present around the sun. We will both look at the distribution of a key radioactive nuclide in this nebula and the separation of gas from solid at the beginnings of planet formation. This will tell us about the compositions of planets likely to form and whether or not they will melt extensively.

A major event in the history of a growing planet is the sinking of metal to its centre, forming a core. This is well understood on Earth, but not for smaller planetary bodies. We will use a novel, isotopic measure of the size of cores in one of the largest asteroids (Vesta), the Moon and Mars. This new approach is made possible by our ability to make precision isotopic measurements and couple them with melting experiments in the lab. The idea behind this approach is that we have few samples of these planetary bodies and the techniques used on Earth do not work well for such samples, which have experienced unknown perturbation en route to the surface. We have strong reason to believe this does not occur for Ni isotopes and so they record a robust signal of core formation in small bodies.

Although the formation of some small planetary bodies, like Vesta, is thought to be well understood, the origin of our closest companion, the Moon has long proven problematic. What appeared successful models of its dynamics fail to account for its marked chemical similarity with the Earth. To address this a new suite of models have been proposed, which represent a radical departure in the style of formation. However, it is still not know how the Moon actually forms from the vapour cloud formed in such collisions. This is the focus of our fourth project which will further see if the new models can also explain the identical isotopic compositions of Earth and Moon.

The interior of the Earth is difficult to probe, but the dynamics of the Moon's interior is yet harder. Seismic techniques are used on Earth and there are some seismic records of the Moon. These noisey data are difficult to process, but advances in processing terrestrial data make it time to re-examine the information carried in the lunar archive. In particular, the project will look for anisotropy- caused by the preferential alignment of objects. This has proven very successful on Earth and may reveal a more detailed picture of motions within the lunar interior and whether or not this relates to obvious features on the surface.

Finally our planetary exploration focuses on the active atmosphere of Saturn's satellite Titan. Using spectroscopic observations from spacecraft and new, high-resolution, ground-based data, the project will examine the distribution of oxygen bearing molecules in Titan's atmosphere and use this information to test models of the processes that produce and move these species. This will provide a window into understanding the active atmosphere of a distant planetary body.

There are important industrial applications of both chemical (isotopic), physical and numerical approaches developed in this proposal.

Links with industry in all of these disciplines is well established within the group at Bristol, which allow for ready impact.
Namely, the isotope lab works closely with a major instrument manufacturer (Thermo Fisher, Bremen) and is currently exploring the possibility of commercialising a novel mass-spectrometer built in collaboration between these two parties.
Bristol runs regular meetings between industrial and academic seismologists (BUMPS) which show cases new techniques and has provided an important conduit for successful developments to be adopted by industry. Programming which forms part of this work will directly feed into commercial applications from small spin out companies to the insurance industry.

The group at Bristol is very active in Outreach, from major public events at the University (e.g. the annual Colin Pillinger lecture), to advising the media (through BBC Bristol and related outlets) and giving guidance about purported meteorite finds. We have a well organised programme to engage with local schools, organised centrally through the University. This ranges from hosting secondary school summer project students to awe-inspiring show-and-tell in primary schools. We hope to have further influence by rolling out some of our materials using the GeoBus- funded by another RCUK programme but with which we have close links.