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.
- 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.
- Science From the Moon -
David DeBoer (Astrophysics), Kris Zarbadami (Astrophysics) and Neil Bowles
We uniquely rely on radio telescopes to understand the bulk of baryonic matter in the early Universe and the evolution of the Universe across early Cosmic times. There are two unavoidable limitations to our exploration of the Cosmos with terrestrial-based radio telescopes:
(1) the prevalence of interfering radio transmissions from human activity, and
(2) the Earth’s ionosphere and atmosphere, which are opaque or disruptive to many important radio frequency ranges.
These limitations are overcome by reaching above the atmosphere and beyond Earth, a capability that, to date, has generally been the exclusive purview of expensive, government-funded space-based “Great Observatories”.
However, we are now on the cusp of a new era, with cost-effective and opportunity-laden access to space (including the lunar surface) becoming a reality. Such unfettered access will enable disparate groups to send instruments there, bringing about a transition from Earth-based observatories to space-based and cislunar telescopes (Fig. 1). Although this shift provides exciting opportunities for new science, it will also introduce sources of radio frequency interference (RFI) to the quietest remaining location to which we have access: the lunar Farside. Measurements from a generally RFI-free environment must be taken before the lunar skies have a multitude of orbiters.
One mission in the planning stage is the Lunar Farside Technosignature and Transients Telescope (LFT3). Being led out of Oxford, this mission would seek to arrive on the lunar farside surface before 2030, to take unique-in-history measurements from 1 - 2700 MHz.. The science case is wide and spans technosignatures, transients, cosmology and lunar studies [https://github.com/ScienceMoonshot/LFT3Memos/blob/main/LFT3_White_Paper.pdf]. This project would explore instrumentation for scientific outcomes for LFT3 and any potential “ride-along” instruments. This could include all mission aspects as well as foundational and preparatory science and instrumentation. The overall goal is science from the Moon, which also includes regolith studies and operations from the Moon. Specifically, this project would work with the LFT3 instrument design and strive to maximize the scientific impact of the data to be collected from the Moon at this unique time.
- 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 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.
- Exploring clouds and gaseous abundances in the atmospheres of Uranus and Neptune -
Uranus and Neptune, known as the “Ice Giants” are amongst the most mysterious and poorly understood planets in our solar system. The poles of Uranus are tipped over by an extraordinary 98º (compared with an obliquity of 23.5º for the Earth) leading to enormous annual variations in solar forcing, with the poles annually receiving more sunlight per unit area than the equator! In contrast, Neptune’s obliquity of 29º appears much less anomalous. The Voyager 2 fly-bys in 1986 and 1989 provided our only close-up views of these worlds and revealed that Uranus is in almost perfect radiative balance with the Sun, while Neptune emits thermally more than 2.5 times the solar radiation it receives! Perhaps as a result of this imbalance, the atmospheric circulation of Uranus was found to be rather quiescent, while that of Neptune was extraordinarily dynamic and active.
More than a quarter of a century later, the spatial resolution of ground-based telescopes has been transformed by the development of adaptive optics. The activity of Uranus’s atmosphere increased dramatically through its equinox in 2007, while Neptune’s atmosphere shows enormous changes in cloud activity. We have been monitoring and these developments with an extensive programme of near-infrared ground-based observations at the Gemini-North Telescope in Hawai’i and ESO’s Very Large Telescope in Chile. Near infrared reflectance spectroscopy enables us to determine the vertical and horizontal distribution of cloud and gaseous abundances in these atmospheres, using our world-leading NEMESIS retrieval code. Recent highlights include: 1) the first positive detection of hydrogen sulphide in the atmosphere of Uranus (https://www.ox.ac.uk/news/science-blog/what-do-uranuss-cloud-tops-have-common-rotten-eggs) and probable detection in Neptune’s atmosphere; 2) the first ground-based detections of methane latitudinal variability in Uranus and Neptune’s atmosphere; 3) a ‘holistic’ cloud model that matches the observed reflectivity spectra of both Uranus and Neptune from 0.3 to 2.5 microns, and can explain the difference in colour between these two worlds (https://www.ox.ac.uk/news/2022-05-31-scientists-explain-why-uranus-and-neptune-are-different-colours, https://www.ox.ac.uk/news/2024-01-05-new-images-reveal-what-neptune-and-uranus-really-look-0); 4) the first ground-based detection of a dark spot in Neptune’s atmosphere and the first EVER spectral characterisation of such a spot (https://www.eso.org/public/ireland/news/eso2314); and 5) a new calculation of Uranus’s radiative heat balance showing it to emit slightly, but significantly more radiation than it absorbs from the Sun, pointing to an extant internal heat source (https://science.nasa.gov/missions/hubble/nasa-oxford-discover-warmer-uranus-than-once-thought/).
The aim of this project is to develop and extend our ground-based visible and near-infrared observing programme and combine these new observations with existing thermal infrared determinations and also with recently acquired observations made with the James Webb Space Telescope. The combination of thermal emission and reflected sunlight observations should enable us to build up a self-consistent picture of the circulation and cloud-forming processes at work on the ice giants during a period of rapid change. This project is particularly timely given that a dedicated space mission to one of the Ice Giants was recommended by the 2022 NASA Decadal Survey in Planetary Science. Hence, the Ice Giants are currently a ‘hot topic’ and the successful candidate would be joining a well-established planetary data analysis group that is actively involved in both observational astronomy and planetary missions.
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)
Venus is likely to be volcanically active today. Hints of this come from a variety of observations, from radar to gravity mapping, and also from the very nature of its thick atmosphere and cloud layer. The cloud layer, extending from about 50 – 70 km altitude and composed primarily of sulphuric acid mixed with water, is known to contain other (as yet unidentified) minor constituents. Might this include volcanic sulphate aerosols or ash particles? Might volcanic plumes of water vapour, sulphur dioxide or other gas species be snaking their way across the planet?
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 due 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 cloud constraints from missions such as Venus Express will be applied to simulate different methods of hunting for atmospheric traces of volcanic activity. The focus will be on orbital measurements, in particular from the VenSpec suite on ESA’s upcoming EnVision orbiter, but the project can be extended to include other missions, observation types, or ground-based telescope observations.
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 Kloewer 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.
- Weather in exoplanet atmospheres -
Planetary atmospheres are not static entities, rather they are dynamic with emergent short-timescale variability - i.e., “weather.” All Solar System planetary atmospheres undergo time-variability, so it is expected that exoplanet atmospheres are also variable. The variability of exoplanet atmospheres has been potentially inferred from recent space- and ground-based observations, and the James Webb Space Telescope (JWST) will enable characterisation of the detailed properties of such atmospheric variability for hot gas giant exoplanets. There is a need to develop both analytic theory and numerical simulations to ascertain the nature of the atmospheric variability on close-in exoplanets that are expected to be tide-locked to their host star. Previous work has predicted the expected level of variability from either idealised numerical simulations or a small number of simulations of specific planets, but there is no theory for how the variability on tide-locked planets scales with planetary properties and the inclusion of non-linear feedbacks due to processes such as latent heat and clouds.
One DPhil (PhD) student is sought for this project to study weather in tide-locked exoplanet atmospheres. I am open to working on hot gas giant planets that can be characterised with JWST and/or temperate rocky planets that serve as comparison sets to Earth. This DPhil student will work in collaboration with members of the planetary climate group at Oxford and outside collaborators including experts in atmospheric dynamics and experts in atmospheric observational characterisation. The student will use the ADAM (SPARC/MITgcm) model and/or the ExoCAM general circulation models to simulate atmospheric variability, and will also use pencil-and-paper theory to understand the mechanisms driving variability in greater detail. As part of this project, the student will work to advance and modernise the SPARC/MITgcm and/or ExoCAM modelling frameworks, in collaboration with their userbases.
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 ExoCAM and MITgcm), and MATLAB (MITgcm). A keen familiarity with computer programming is required, while prior experience with Fortran, Python, and MATLAB is desirable but not required.
- Simulating the combined 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 the climate and observable properties of exoplanets. 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 the planetary climate group at Oxford, 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 modernise the SPARC/MITgcm and/or ExoCAM modelling frameworks, in collaboration with their userbases.
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 ExoCAM and MITgcm), and MATLAB (MITgcm). A keen familiarity with computer programming is required, while prior experience with Fortran, Python, and MATLAB is desirable but not required.