Planetary Science at Oxford Physics 2019

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This proposal in planetary physics ranges from studying the atmospheres of the giant planets through to studying the reflectance and thermal properties of airless bodies such as asteroids, which are the primary ways in which these bodies can be studied. The programme outlines a coordinated effort to: 1) measure and understand the fluid circulations, cloud condensation and photochemistry in giant planet atmospheres, both within the Solar System and beyond; and 2) measure and interpret the spectra of airless planetary bodies to better understand their origins, composition and regolith structure. We have four complementary main projects. Project 1: Recent results from the Juno mission have indicated that the complex, zonally banded atmospheric circulation of Jupiter (and probably Saturn) is neither very deep compared to the planetary radius, nor confined solely to a shallow 'weather layer'. This leaves unanswered a host of key questions concerning the dynamical origin of their meteorology and the resulting transport of heat and material tracers within these iconic and prototypical planetary bodies. In this project, we will test and evaluate possible dynamical mechanisms for energizing the principal features of the atmospheric circulations of Jupiter and Saturn, using a combination of innovative analyses of the observed wind and thermal structure from Cassini, Voyager, Juno and other spacecraft, and a state- of-the-art global numerical circulation model of the deep weather layers of Jupiter and Saturn. Project 2: How do clouds form in the atmospheres of the Giant Planets? What are they made of and how are they initiated? In this project we will link near-infrared (near-IR) reflection measurements, thermal-IR emission observations and fundamental modelling to explore cloud formation in hydrogen-rich Solar System Giant Planets. This will ultimately benefit the understanding of clouds in both Solar System planets and exoplanets.Project 3: Primitive asteroids (usually assumed to be C- and B-type asteroids) hold important clues to the formation and evolution of the Solar System. In this project, enabled by our roles as the UK's only Co-Investigator and Participating Scientist, we will use data from NASA's OSIRIS-REx mission to study primitive asteroid Bennu in preparation for sampling of its surface in 2020. As part of the mission's science team, and using our bespoke laboratory and numerical modelling capabilities, our work will place the returned sample into geologic context and also help determine Bennu's place in the wider context of the Solar System's asteroid populations. Project 4: Remote sensing measurements in the thermal infrared (TIR) can be used to determine the composition and physical properties of an airless body through spectroscopy and temperature mapping. Surface temperature datasets are being acquired by missions including NASA's Lunar Reconnaissance Orbiter (LRO) and OSIRIS-REx, and to interpret them correctly requires new laboratory measurements. This project addresses how thermal emission varies with observation angle, surface roughness and porosity by using and upgrading a unique experimental facility, the Oxford Space Environment Goniometer, to make targeted laboratory measurements to maximise the return from these new and future datasets.