Below is a list of available DPhil projects for Planetary and Exoplanetary Physics. If you are interested in any of the following research areas, please contact the relevant supervisor directly as they will be happy to have a dialogue with you. Please note that additional exoplanet projects are available as a DPhil in Astrophysics (exoplanets and stellar physics).
Some projects may be filled as applications are reviewed, so we particularly encourage any candidates considering an application after the January deadline to contact prospective supervisors about available project options.
- Studying the Moon’s water and composition from Lunar Trailblazer -
The Lunar trailblazer spacecraft is due to launch in Spring 2024 carrying two instruments to lunar orbit to map temperature, composition and variation in small amounts of water on the Moon. One of the instruments is the Lunar Thermal Mapper, a multispectral thermal imager built here in Oxford Physics. This project will look at the data returned by the mission and work with our laboratory spectroscopy facilities to map surface composition, study the evolution of the lunar water spectral signature and the temperatures of the lunar surface to help us understand how the Moon formed and evolved and plan for future human and robotic exploration.
This project will involve the joining our existing team to work on the analysis of data from space instrumentation built in the department. A first degree in physics/astrophysics/Earth Sciences or an engineering related discipline is required.
- Preparing for Comet Interceptor -
Working with colleagues in Finland, France and the US, Oxford Physics are leading the development of the multi and hyper spectral imager for the European Space Agency’s Comet Interceptor mission due for launch in 2029. Our instrument is called MIRMIS and will remotely map the temperature and composition of the comet’s nucleus and coma. As part of the instrument team you will be working on the test and calibration of our instrument and connecting the performance testing science analysis to feed into the instrument operations.
This project will involve the joining our existing team to work on the development and testing of equipment for testing space instrumentation, including the optical instrumentation. A first degree in physics/astrophysics or an engineering related discipline is required.
- Testing the Ariel Exoplanet space telescope -
Oxford Physics are part of the international team helping to develop ESA's ARIEL Exoplanet space telescope due for launch in the late 2020s. ARIEL is a 1 m class telescope that will be located at the 2nd Earth-Sun Lagrange point to carry out the first detailed transit spectroscopy survey of more than 1000 exoplanetary atmospheres. Our group, supported by the UK Space Agency, are working on the optical ground test equipment to verify the performance of the integrated payload before launch.
We are recruiting a PhD candidate to join our team to support the payload-level testing of the ARIEL space telescope as a member of the ARIEL Mission Consortium. Initial work will involve simulating the payload tests to optimise the planned methods to calibrate the ARIEL instruments. The PhD candidate will then support the payload test campaign in person at RAL Space. There will then be detailed analysis of payload and instrument test data to confirm that the performance of the payload verifies mission requirements. There will also be scope to shape the planned commissioning activities of the payload in-flight based on the developed methodology for the ground tests.
This project will involve joining our existing team to work on the development and testing of equipment for testing space instrumentation, including the optical instrumentation. A first degree in physics/astrophysics or an engineering related discipline is required.
- Exploring asteroids in the thermal infrared using OSRIS-REx -
Using data from meteorites and OSIRIS-Rex to map asteroid composition and how that feeds into Solar System evolution. Oxford Physics are part of the OSIRIS-REx sample analysis team and we are interested in connecting laboratory measurements now being made on the sample returned from asteroid Bennu to the observations made during the orbital reconnaissance phase of the mission. This project will work with our infrared spectroscopy laboratory to measure samples from meteorites, analogue materials and potentially samples returned by OSIRIS-REx to connect lab scale measurements to the larger areas measured on Bennu and apply them to observations of other asteroids being made in the thermal infrared by ground and space based telescopes.
- Exploring the surfaces of Saturn’s icy satellites -
Saturn’s icy satellites are diverse and remain enigmatic, despite years of study by NASA’s Cassini mission. The satellites vary in colour, size, and activity. Some, like Mimas, are long dead and show the scars from years of impactor bombardment. While others, like Mimas’ neighbour Enceladus, have active plumes that send ice and dust into space. Understanding the surface of these targets is crucial in understand their role in the Saturn-system, how they interact with Saturn’s rings, high-energy particles, impacting populations, and even whether they could even host life.
Enceladus’ geysers erupt from four fractures that span its south polar region. The resulting plume escapes the moon, forming a ring around Saturn called the E-ring. Exactly why and how the plumes are formed is unknown, but the eruptive material is thought to come from a liquid water ocean, held beneath Enceladus’ icy surface. Whether this ocean supports life is arguably one of the greatest current mysteries of our solar system.
The high-energy electrons that orbit Saturn bombard the surface of Mimas, Tethys and Dione. This bombardment damages their water-ice surfaces, effectively gluing grains in the surface together, which stops it from cooling down at night as much as their surroundings. This surface alteration also changes its colour, making it appear more blue. How this bombardment alters with electron energy, surface depth, and whether such alteration could be occurring elsewhere in the solar system is still poorly understood.
Cassini studied the Saturn system from 2004 until 2017, during which time a wealth of data was obtained on Saturn’s icy satellites. I am seeking one DPhil (PhD) student to continue my work in analysing Cassini’s Composite Infrared Spectrometer (CIRS) data, specifically to analyse eclipse observations made of Saturn’s icy satellites. Eclipse observations are powerful because they allow the very surface (top few mm) of an icy world to be probed. This region is otherwise difficult to study, but yet vital to understanding everything that happens beneath it. Eclipse observations were made of most of Saturn’s icy moons, so could inform on how Enceladus’ plume recoats its surface, and how the very near surface of Mimas/Tethys/Dione is altered by electron bombardment.
The study of icy worlds has a strong future. The upcoming NASA mission “Europa Clipper” will launch in 2024 to study Jupiter’s icy world Europa, and NASA’s Lucy mission launches in late 2021 to study Jupiter’s Trojan asteroids. As a Co-I on both of these missions future opportunities exist for expanding into these targets. The successful candidate would be joining a well-established planetary science group, which is actively involved with many planetary missions and astronomy. International collaborations are include working with other modelling groups located in the USA and Switzerland.
The work will be computationally intensive, using programming languages like IDL and python, so a physics/computing/mathematics background is preferred, and a first degree in Physics, Mathematics or a related discipline is required.
- Plume Hunting on Europa -
Multiple studies have found evidence of plumes erupting from Jupiter’s icy satellite Europa. However, the source of these plumes has yet to be discovered. Observations returned by NASA’s Cassini mission have shown that certain colour images are diagnostic in looking for plume deposits. However, maps of Europa at the required colour ratios have yet to be produced. This project would combine images of Europa taken by a variety of missions to produce colour ratios at diagnostic bands to search for plume deposits.
The research would involve correcting images to account for changes in lighting, mosaicking them to form larger (near-global) maps, and then using the maps to search for surface alteration including plume in-fall. This will include comparing the maps to predicted plume-source locations, and to other surface alteration processes (e.g. geological maps, radiation bombardment). The results will be fed into the plume search conducted by NASA’s Europa Clipper spacecraft, with the student being able to directly interact with that team.
- Exploring the Ices of the Outer Solar System in a Lab -
The surfaces of the outer solar system are diverse and enigmatic. Data taken by spacecraft have shown icy worlds to be enigmatic, diverse, and rich with astrobiological potential. Data from Cassini showed Saturn’s moon Enceladus to be highly active, while Hubble Space Telescope Observations (HST) hint at plumes on Europa. However, in order to correctly interpret the returned data we need to understand how the cold exotic ices in the outer solar system reflect and conduct light.
This project is to help create and develop a new ice laboratory, to test the thermophysical properties of ice at extremely low (<50 K) temperatures. Starting with water ice, before moving into more exotic ices (carbon monoxide, nitrogen, methane, carbon dioxide). The results will be tested against existing Cassini and New Horizons data, and eventually Europa Clipper data too.
- Unveiling the clouds of Jupiter, in support of NASA Juno and in preparation for ESA/JUICE -
The NASA Juno mission arrived at Jupiter in July 2016 and entered into a series of elliptical polar orbits designed to probe Jupiter’s interior structure through measurement of its gravity and magnetic fields and remote sensing of its deep atmosphere. Juno’s highly elliptical orbit minimises the damaging effects of Jupiter’s extremely harsh radiation belts, but means that its visible and near-IR observations with the JIRAM instrument are mostly of Jupiter’s poles, while microwave observations using the MWR instrument are mostly confined to narrow north-south swaths during ‘perijove’ (closest approach) passes that lack the global spatial context necessary to interpret them fully. Hence, a global campaign is under way to provide Earth-based observational support for Juno, and our group has been making semi-regular observations of Jupiter with the MUSE (Multi-Unit Spectroscopic Explorer) instrument at ESO’s Very Large Telescope (VLT) in Chile. These MUSE observations allow us to map the spatial distribution of the clouds, cloud-colouring agents (called chromophores), and ammonia with remarkable resolution, which we are using to wholly revise our understanding of Jupiter’s atmosphere (e.g., https://ora.ox.ac.uk/objects/uuid:a5856d5a-eba1-487b-82c5-0a31761ff218, https://arxiv.org/pdf/1912.00918.pdf) with our world-leading NEMESIS radiative transfer code (https://nemesiscode.github.io), for which a new python-based has been developed that will be publicly released in the next few months.
In this project, we wish to extend out MUSE analyses by comparing them directly with observations made by the MWR and JIRAM instruments on Juno, whose datasets are publicly available. In addition, NASA’s James Webb Space Telescope (JWST) has made fantastic new near-infrared and thermal-infrared observations of the Jovian atmosphere, which can also be co-analysed with the Juno data. Taking all these data together we hope to develop an holistic model of Jupiter’s clouds and ammonia distribution. Planning even further ahead, the project supervisor, Patrick Irwin, is a co-investigator of the MAJIS near-infrared mapping spectrometer on ESA’s JUICE mission, which was launched in 2023, and will arrive in the Jupiter system in 2031. Hence, advances made now will have a direct impact on planning the observations that JUICE will make.
The student would work alongside Prof. Irwin and his group to develop one of the strands of this overall project, where the student will learn about retrieval modelling techniques, data analysis, and how spectral modelling observations of planetary atmospheres are performed. While this project concentrates on a solar system planet, the skills learned can be readily applied more generally to other solar system planets and exoplanets also.
Since this project will be computationally intensive, using python and other codes (e.g., Fortran, IDL), a physics/computing/mathematics degree is preferred.
- Radiative Fluxes in the atmosphere of Venus -
Patrick Irwin and Colin Wilson (ESA)
It’s always cloudy on Venus. Its main cloud deck extends from about 50 – 70 km altitude and is composed primarily of sulphuric acid, mixed with water, and there’s evidence for the existence of minor constituents in the main cloud deck and at other altitudes, of unknown composition – and possibly ash and dust in the atmosphere below. The clouds and particulates have a huge effect on both solar and thermal radiative fluxes in the atmosphere, playing a major part in greenhouse warming and in forcing the atmospheric circulation. Measuring these fluxes therefore is critical for understanding the dynamics of the atmosphere.
A new generation of orbiters and probes is being developed to explore Venus: ESA’s EnVision orbiter, NASA’s VERITAS orbiter, and NASA’s DAVINCI entry probe are all approved for launch within the next decade, and long-lived balloon-borne missions are being studied. Each of these missions will carry cameras and/or spectrometers, to study the surface and atmosphere.
In this studentship, modern radiative transfer codes and new cloud constraints from missions such as Venus Express will be applied to improve our understanding of processes in the clouds of Venus and their variability. Calculations to optimise spectral channels for future probe- or balloon-borne radiometers will be performed. Further calculations relevant to surface imaging and/or solar power availability could also be performed, depending on research priorities and mission opportunities as the project progresses.
Since this project will be computationally intensive, using python and other codes (e.g., Fortran, IDL), a physics/computing/mathematics degree is preferred.
- Differentiable atmospheric modelling: Learning from data between Earth’s and exoplanetary climates -
Supervisors: Milan Klöwer and Thaddeus Komacek
Atmospheric general circulation models are the backbone of climate models, being used to understand and predict climate change on Earth. Founded in physical laws, general circulation models can be generalised to exoplanetary atmospheres. While many atmospheric processes on Earth are well understood and accurately simulated as evident through the success of weather forecasting, some processes such as cloud formation and precipitation are less certain. Societally-relevant surface climate and extreme events like heat waves, however, strongly depend on those. At the same time, observations can constrain such uncertainties, improving climate predictions on Earth. On exoplanets this will reveal insights about the parameter regimes in which planetary habitability is possible. How to make atmospheric models automatically learn from observational data?
This project will build on top of SpeedyWeather, an atmospheric general circulation model written in the Julia programming language. SpeedyWeather is easy to use and extend, inspired by modern software engineering, covering functionality from data visualisation to high-performance computing. The candidate will continue to develop its differentiability through the automatic differentiation framework Enzyme. Differentiating through SpeedyWeather, we can optimise the unknown or less certain parameters determining the planetary surface climate and resulting habitability in the same way as neural networks are trained towards observations. And we can add neural networks to SpeedyWeather forming a hybrid physics and data-driven model.
For exoplanets, observations of gas giants down to hot terrestrial planets are currently used to constrain their atmospheric composition and thermal structure. Critically, upcoming space missions such as the Large Interferometer for Exoplanets and Habitable Worlds Observatory will have the ability to measure the thermal emission and reflected light of Earth-like exoplanets, enabling a direct test of our Earth-based understanding of planetary climate. This SpeedyWeather/Enzyme framework will enable novel rapid inverse characterization of exoplanetary atmospheres with a 3D model that can be applied to exoplanet observations.
Part 2 of this project will scale up the same method to the Earth’s atmosphere, increasing data and complexity. For earth, the current surface climate is observable, but a model may still mispredict frequencies and intensities of extreme events like heat waves under global warming. But with automatic differentiation we can train the model to correct for the missing physics of heat waves towards a more reliable generalisation into future climates, assessing the Earth’s habitability under global warming.
This PhD project will bridge several fields: The applicant is expected to have a strong background on the spectrum between physics, mathematics, and computer science, with enthusiasm for computer science and machine learning. Prior experience with Julia is not required, but experience with another programming language like Python, Matlab, C(++), or Fortran is preferred.
- Simulating the impacts of clouds and hazes on the climate and observable properties of the diverse range of exoplanets -
Clouds and/or hazes are found on every planet in the Solar System with a thick atmosphere and can have a profound impact on their climate and observable properties. They are expected to be present in all exoplanetary regimes that are currently observationally accessible, including in the atmospheres of close-in hot and warm Jupiters and temperate and warm Sub-Neptunes. Clouds and hazes in these atmospheres have already been found to impact their observable properties accessible with ground- and space-based telescopes through the muting of spectral features in transmission, reflected light patterns accessible via phase curves, and population-level trends in spectra. In addition, clouds and hazes are expected to shape the climates of temperate terrestrial exoplanets in the habitable zones of a range of host stars, and may significantly mute key spectral features of biosignatures or habitability indicators in transmission. As a result, comprehensive 3D models that incorporate cloud and haze microphysics are required to make the best use of current and future observational data of exoplanet atmospheres.
One DPhil (PhD) student is sought for this project to study the impacts of clouds and hazes on exoplanetary atmospheric circulation, climate, and observable properties. I am open to working on simulations in a range of planetary regimes, including terrestrial planets, sub-Neptunes, and gas giants in a variety of irradiation regimes. This DPhil student will work in collaboration with members of my group, outside collaborators who are experts in atmospheric dynamics and cloud and haze microphysics, and the SPARC/MITgcm and/or ExoCAM hot Jupiter userbases more broadly. As part of this project, the student will work to advance and modernize the SPARC/MITgcm and/or ExoCAM modeling frameworks, in collaboration with their userbases. I am also open to support students who would prefer to define their own research direction in the area of exoplanet atmospheric dynamics, climate, and/or internal evolution.
This work will require a thorough understanding of fluid dynamics and radiative transfer, which require a solid background in mechanics, electricity and magnetism, thermodynamics, and quantum mechanics, as well as the mathematical methods of physics. As a result, a degree in physics, mathematics, geophysical sciences, astrophysics, or a related discipline is required. This project will be computationally intensive, with coding in Fortran (MITgcm, ExoCAM), Python (gCMCRT and PSG post-processing and analysis of MITgcm and ExoCAM), and MATLAB (MITgcm). A keen familiarity with computer programming is required, while prior experience with Fortran, Python, and MATLAB is desirable but not required.
- Exoplanet climate dynamics -
The newly discovered exoplanets present possibilities for a diverse range of climate situations not encountered in our own solar system. The demands of this new subject challenge the limits of current modelling capabilities, and while they involve the same underlying physical components as are familiar from the Solar systems, these components are present in novel combinations. This project involves a range of modeling and theoretical activities aimed at understanding the new climates. There is a particular emphasis on identifying potentially observable consequences of various exoplanet climate phenomena. I am seeking up to two DPhil (PhD) students for work in the general area of exoplanet climate modeling, with a particular emphasis on smaller planets (roughly 3 Earth radii or smaller. ) which can have a more rich diversity of atmospheric compositions than the hydrogen-dominated gas giants. This class of planets include both dominantly rocky planets (habitable or not) as well as subNeptunes which have a much more substantial low molecular weight (compared to rock) envelope than Earth or Venus. In all of our work, there is an emphasis on maintaining an appropriate balance between theoretical work or idealized modeling aimed at elucidating fundamental principles, and work with more comprehensive general circulation models.
I am open to student-led suggestions with the general scope of my broad interests, but there are two particular project areas I wish to highlight at this time: (1) Lava Planets These are planets which are hot enough to have a permanent molten rock ocean on the dayside, Their atmospheres may consist of thing rock vapours outgassed from the magma ocean, or may also include lower molecular weight noncondensing substances such as carbon dioxide. One of the main advances needed is the development of a model of thin rock-vapour atmospheres that resolve vertical structure, but can also handle the transonic flow of such atmospheres and the great range of surface pressure between dayside and nightside. (2) SubNeptune thermochemical evolution modelling, SubNeptunes typically have quite a substantial rock fraction (70% to 95%) but the low molecular weight envelope (a mixture of hydrogen, helium, water in various phases, carbon dioxide, methane, and other molecules) is still thousands of times more massive than on rocky planets such as Earth or Venus. There is a need for models that couple atmospheric radiation, dynamics and thermodynamics with the evolution of the deep envelope and the rocky interior. The envelope-rock interface in most cases takes the form of an interface with a magma ocean, at which chemical transformations can take place.
In both cases, we have acquired James Webb Space Telescope data with which to challenge models, and there is a wealth of new observational data in the pipeline, plus a chance to participate in observing time proposals.
In addition, we have ongoing work on the silicate weathering and deep carbon cycle processes that determine atmospheric carbon dioxide content on habitable worlds.
These projects require a thorough understanding of fundamental physics, including thermodynamics, mechanics and electromagnetic radiation, as well as a facility with analysis of mathematical models. Familiarity with physical chemistry is also desirable. Hence, a first degree in Physics, Mathematics or a related discipline is required. The projects involve considerable use of computational techniques, so basic familiarity with numerical analysis and familiarity with programming techniques in some computer language is required. The main programming languages used are Python and Fortran, but prior experience with these specific languages, while desirable, is not required.