Planetary Science at Bristol

We will make a timely return to a legacy of the manned Apollo 12-16 missions to the moon: an extensive seismic dataset. This dataset recorded of over 12500 'moonquakes' has been used extensively to image the deep structure of the moon, but these studies only provide a static picture. Seismic anisotropy enables us to probe subsurface dynamics, but its measurement is challenging for the complex lunar data. Recent advances in analysis techniques developed for noisy terrestrial data now make these measurements possible. Such measurements can be used to probe processes such as convection in the lunar mantle, or even tell whether there are still hot, molten traces of the moon's fiery birth deep in the interior.

Unlike the Earth's moon, Saturn's giant moon Titan, has a thick atmosphere with an exotic mix of nitriles and hydrocarbons. Titan provides a natural laboratory to test our understanding of atmospheric chemistry and physics. There are also many similarities with Earth including polar vortices and distinct polar chemical compositions, that can provide insight into our own planet. A wealth of data from the Cassini spacecraft and the James Webb Space Telescope, will be used to study Titan's atmosphere. In particular we will examine the role of atmospheric waves, extreme cold and polar feedbacks, and orbital influences on Titan's seasons.

As well as the large moons, we will also study small, asteroid bodies. In particular, we will attempt to explain surface features discovered on high definition images obtained by recent missios. We seek to explain 'lowland' topography. The goal of this research is to understand how changes in shape, spin-period, and overall size of the asteroid influence the formation of lowlands, to assist in the selection of future targets for sample return missions.

Vaporisation occurs when planetary objects collide, as an inevitable part of their growth in the gas-dust disk around the proto-Sun. Yet it was previously assumed that the less volatile major building blocks, silicon and magnesium (1/3 Earth's mass) were unaffected. New measurements from our group suggest ~50% of Earth's original mass was vaporised, challenging this paradigm. However, there are no experimental data to substantiate the importance of vapour loss in shaping planetary compositions. We propose innovative experiments and analysis to determine the necessary liquid-vapour chemical interactions and address this knowledge gap, allowing us to better model planetary forming processes.

Water is vital to understanding the formation and habitability of terrestrial planets. At the birth of the Solar System small planetary bodies formed through the accretion of dust, mineral grains and sometimes ice. The addition of water and other volatile elements to these small planetary bodies may have taken place in the inner Solar System asteroid belt or near Saturn and Jupiter's orbit. Distinguishing between these scenarios is critical for models of planetary growth. Some meteorites contain small amounts of water trapped in minerals over this long time period. In this project we will analyse the isotopic composition of this water to fingerprint to where in the Solar System it was added.

A prime constituent of many asteroids and meteorites are millimetre sized, quenched melt droplets or chondrules. These objects formed in the first few million years of solar system history, although exactly when is a matter of considerable debate. It is a challenging problem as we need to distinguish time periods of less than 1million years in objects more than 4.5 billion years old. Yet it is important problem to be able to reliably map the formation of chondrules on the appropriate time period in a rapidly evolving early solar system. We will apply a novel dating approach we have developed as part of previous STFC funding to hopefully reconcile currently contrasting interpretations.

There are important impacts of our work for other academic disciplines, industry and public outreach.

Links with industry are well established within the planetary group at Bristol.
The isotope lab works closely with a major instrument manufacturer (Thermo Fisher, Bremen) and is in an on-going process of developing new commercially attractive, mass-spectrometric capabilities. The new analytical possibilities provided by a one-of-a-kind mass-spectrometer is also being investigated for potentially in opening up a market in bio-medical research. With a ERC Proof of Concept grant and collaboration with a spin out company, we are developing a method for rapid measurement of Ca isotope ratios as a means to provide an effective new method to screen for bone wastage. We are also developing applications of our measurement procedures to trace urban pollution with the academic partners in the medical school at Bristol
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. Current work on the InSight project is of particular relevance for this community.

The group at Bristol is very active in Outreach, from major public events at the University, to advising the media (through BBC Bristol and related outlets). The planetary group has recently had several high profile contributions to national TV and we will continue with the contacts made through this process. We have a well organised programme to engage with local schools, organised centrally through the University but driven by the skill and enthusiasm of researchers in the planetary. This ranges from hosting secondary school summer project students to awe-inspiring show-and-tell in primary schools.