Solar System Planetary Science at Oxford 2016-2019

Lead Research Organisation: University of Oxford
Department Name: Oxford Physics

Abstract

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 soil structure. We have four main projects that are complementary.

1. The first project explores the dynamic atmospheres of Ice Giants, Uranus and Neptune, by studying seasonal changes during a period when Uranus is changing rapidly following its Northern Spring Equinox in 2007, and comparing its atmosphere with the dynamic, turbulent atmosphere of Uranus' sister planet, Neptune. A key part of our study is to understand the generation and evolution of convective storm clouds now regularly seen on both planets. We will improve the retrieval techniques used to interpret such data and couple these with other information, such as models of cloud condensation, to yield more self-consistent solutions. By exploring the thermal balance in these atmospheres we will look for imbalances that might reveal the details of dynamical or condensation processes. This project has overlap with Projects 3 and 4.

2. Our second project builds on our world-class laboratory measurement programme to understand planetary, asteroid and comet surfaces. We will determine the ways in which visible and infrared light is both emitted and reflected by different surfaces, under conditions equivalent to those in space with extreme variations of solar heating. These data will be crucial to interpret observations made by NASA's OSIRIS-REx asteroid sample return mission, an ongoing lunar programme, and the Jovian satellite component of Project 3.

3. Our third project explores the interconnections in giant planet systems and builds upon our existing participation with the NASA Cassini mission. It will help us better understand the atmospheric processes linking the interior circulation of Jupiter and Saturn with the weather layer and upper atmosphere of these planets and also to develop techniques to explore environmental conditions on Jupiter's satellites, preparing the way for future observations with NASA's JWST and ESA's JUICE mission. In particular we seek to map Jupiter's evolving atmosphere with ground-based observations in support of the NASA Juno mission to Jupiter (2016-2017). This project will use some of the same tools developed in Project 1 and interpretation of the observations will be aided by the work described in Projects 2 and 4.

4. Our final project examines the atmospheric dynamics of Gas and Ice Giant planets by improving the dynamical modelling of the atmospheric circulation of the Gas Giants (Jupiter and Saturn) and also, in particular, the Ice Giants (Uranus and Neptune). This will help us better understand how the wind structure of these planets is formed and maintained and also determine the role played by clouds and convection driven by condensation of atmospheric water vapour in their climates. This work will help interpret the observations described in Projects 1 and 3.

Planned Impact

Our work is at the cutting edge of modern planetary science, and will bring benefits to the UK through public engagement, scientific advancement and industrial collaboration.

1. Public Engagement: Our group has a very strong track record in public outreach and engagement. Our involvement with several space missions gives us valuable public engagement opportunities, since the largest public interest in space missions tends to occur at crucial moments in a mission's lifetime. Crucial periods foreseen during this grant period include the end of the NASA Cassini mission (2017), the NASA Juno mission (2016-2017), the NASA OSIRIS-Rex mission (2016-2019) and the launch of NASA's James Webb Space Telescope (2018). These events present exciting opportunities to explain and share our scientific discoveries with the general public and students, and to encourage greater participation, enthusiasm and interest in science and technology.

2. Analysis Techniques: The techniques we are developing for better exploiting solar system planet observations will have potential impacts in other areas also. We have recently entered into a new academic partnership with the UK Met Office, which will allow advances we make in atmospheric circulation modelling to be made available to Met Office researchers enabling them to be applied in weather forecasting and climate change prediction. The advanced retrieval techniques we are developing with our radiative transfer and retrieval model, NEMESIS, have the potential to change quite radically the way we think of our place in the Universe since they can be applied not only to Solar System planets, but also to the emerging field of exoplanetary science.

3. Novel Spacecraft Instrumentation: Our space instrument development activity involves collaboration with several UK industrial partners, where we are combining technology we have developed for planetary science instrumentation with subsystems from our partners to enable a new class of radiometers for small Earth observation spacecraft. For example, in July 2014 we celebrated the launch and successful commissioning of the first of these, the Compact Modular Sounder instrument, on the UK TechDemoSat-1 mission in collaboration with RALSpace. The surfaces theme includes the development of a compact infrared spectrometer and we are currently in early discussions with Oxford's technology transfer office (Isis Innovations Ltd) regarding possible commercial uses for this instrument for future Earth observation and ground based applications.

4. Laboratory Surface Characterization: The proposed upgrade to our space environment spectrogoniometer will enable a much wider user group to gain commercial benefit from using this facility, including, for example, by carrying out specialist spectroscopic characterization of high emissivity coatings at multiple emission and reflection angles.

5. Building Connections: Our involvement in the continued preparation for future missions (especially in ESA's Cosmic Vision programme) will inform and enable involvement by UK companies. Current examples include engagement with a major aerospace company regarding spacecraft and mission designs for a Uranus orbital spacecraft and discussions with a UK company to provide detectors for a Saturn probe mission camera (both proposed CV M4 missions).

6. Citizen Science: The increasing ability of amateur observers to provide background monitoring of atmospheric events in planetary atmospheres is a hugely exciting new area of planetary science. Amateur astronomers were responsible for the detection of several planetary storms in the last few years, which led to professional target-of-opportunity programmes and significant resulting publications. Such involvements, however, also give rise to increased engagement by amateur observers, interest from the wider public and coverage by the media.

Publications

10 25 50
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Serigano Joseph (2016) Poster 9: Isotopic Ratios of Carbon and Oxygen in Titan's CO using ALMA in Titan Aeronomy and Climate

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Sylvestre Melody (2016) Seasonal variations of C4H2, C2N2 and C3H4 in Titan's lower stratosphere in Titan Aeronomy and Climate

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Teanby Nicholas (2016) Post-equinox evolution of Titan's south-polar atmosphere in Titan Aeronomy and Climate

 
Description Project 1
Project 1 fully met its objectives relating to both the analysis of observations of Jupiter and the development and exploitation of a new model of its atmospheric circulation in its extended "weather layer". Wind velocity measurements, obtained across much of the planet from the automated tracking of cloud features in Cassini images of Jupiter, were analysed to determine the strength and direction of the exchanges of kinetic energy between different scales of motion, essentially to characterise the turbulent energy cascades in the atmosphere. This is the first time this has been attempted using observations from any planet other than the Earth, and revealed that Jupiter does not fit any classical paradigm for turbulent motion. Rather, we found that kinetic energy is generated (by processes yet to be confirmed) at a horizontal scale of around 3000 km and transferred by interacting eddies to both smaller scales and to larger scales, ultimately energising the prominent banded zonal jet streams. This result is of major importance in providing critical new constraints for comparison with dynamical models. It also indicates some previously unknown close qualitative similarities with the nature of turbulent cascades in the Earth's oceans and is also consistent with new research elsewhere on turbulent regimes in rapidly rotating, stratified fluids. These results are already proving influential among turbulence theorists, and suggest that this diagnostic approach could be applied more widely to other similar observations of gas giant planets.

Our numerical circulation model of Jupiter's atmosphere was also successfully implemented to simulate the dynamics of flow in a deep weather layer, extending to around 160km below the visible clouds, driven jointly by incoming sunlight from above, upwelling heat from the deep interior and the release of latent heat of condensation of water. The model also allowed the formation of condensate clouds composed respectively of ammonia ice, ammonium hydrosulphide and water, forming cloud layers similar to those inferred from observations that were shaped into zonal bands by the patterns of strong winds. The model was run extensively at high spatial resolution on STFC's DiRAC supercomputer facility and used to explore the impact of adding or removing various physical processes. The most comprehensive simulations proved able to capture the formation of Jupiter's strong equatorial and extra-tropical jet streams with realistic wind speeds and structures. They also unexpectedly showed significant promise in representing the deep upwelling of ammonia vapour close to the equator, as later shown in observations from NASA's Juno Mission, though with some deficiencies suggesting missing processes at higher latitudes.

Project 2
The most significant achievement in this project from the award were: a) We made the first ever positive identification of hydrogen sulphide (H2S) above the clouds of Uranus and Neptune using ground-based Gemini/NIFS observations, which suggests that H2S ice is a major component of the main clouds seen. Although the presence of this gas had been suspected from microwave observations, are work positively confirmed it and this has could have significant implications on formation scenarios. b) We detected and quantified, with ground-based VLT/MUSE observations, the cloud top abundance of methane in Neptune's atmosphere and confirmed that its abundance varies from ~4% at equatorial latitudes to 2% at the poles. This confirms previous HST observations, but is the first time that this has been achieved from the ground. c) We developed a highly sophisticated photochemical haze model, which we have begun to use to explore and interpret seasonal changes in haze in Uranus's and Neptune's atmospheres.
Exploitation Route Project 1
For future work, the model could be extended to model both Saturn's atmosphere and the atmospheres of the other giant planets in the solar system. Further work is ongoing in Oxford and in collaboration with UAE University to make further improvements to the model for Jupiter and to adapt the model for Saturn, as well as to explore its ability to capture the observed turbulent cascades of energy and other quantities.

Project 2
We are proposing to take forward simultaneous near/mid-IR observations in the next round of STFC consolidated grant, again from ground, but also this time with JWST. Achieving this would enable scientists to understand how convective storm outbreaks on Uranus and Neptune are initiated and evolve.

The apparent latitudinal variation of H2S arising from this study is puzzling and contrary to that seem at deeper levels. It is also inconsistent with the cloud top methane variation. The data should be analysed again with a greater focus on the discriminating the H2S variations from cloud structure variations. We are planning to do this ourselves.

Finally, the haze model developed in this study could be extended to model the condensation of CH4 and H2S clouds also. This is already being undertaken by us, in collaboration with the formerly STFC-funded PDRA on this project, who is now based in Spain. This would enable us to understand better how clouds form and why, even though CH4 is so abundant, we don't see a thick CH4 cloud at the expected condensation level.
Sectors Aerospace, Defence and Marine,Education

 
Description Project 1) Detection of H2S on Uranus paper was accompanied by a press release and had a high impact. We were Interviewed by several radio stations and had articles in several newspapers and also on the BBC News website. In fact, we were listed at end of 2018 as one of top BBC News science articles of year and also featured in the missing words round of BBC's 'Have I got news for you!'. In addition, the positive detection of H2S means Ice Giant atmospheres are much less absorbing of microwave communication signals than might be the case if NH3 were dominant. This makes it much easier to plan future probe missions. Project 2) A software tool developed under this and a previous UKSA grant to compute the exchanges of potential and kinetic energy between different scales of motion within numerical atmospheric circulation model simulations has been shared with the Global Model Evaluation group at the UK Met Office. They plan to use this to evaluate the performance of their very high resolution weather forecasting and climate prediction models. This is expected to lead eventually to improved weather forecasts and climate simulations, with associated benefits for all users of weather and climate forecasts.
First Year Of Impact 2018
Sector Aerospace, Defence and Marine,Education
Impact Types Cultural

 
Description Planetary Science at Oxford Physics 2019
Amount £1,261,196 (GBP)
Funding ID ST/S000461/1 
Organisation Science and Technologies Facilities Council (STFC) 
Sector Public
Country United Kingdom
Start 03/2019 
End 03/2022
 
Title Mesoscale reanalysis downscaling 
Description A suite of numerical atmospheric models and data assimilation tools that enables a high resolution (5 km) limited-area mesoscale numerical model to be embedded within a global assimilated analysis of the Martian atmospheric circulation. The assimilation combines spacecraft observations of the Martian atmosphere with a global numerical simulation to produce a global analysis of the atmospheric state at moderate resolution (60 km). This time-varying state is then used to provide dynamic boundary conditions to the region being simulated at high resolution by the mesoscale model. 
Type Of Material Improvements to research infrastructure 
Year Produced 2017 
Provided To Others? No  
Impact This method is currently being trialed within the current PhD project to obtain analyses of the meteorology in the vicinity of Gale Crater for comparison with observations that have been obtained from NASA's Curiosity Rover. Preliminary results compare well with the Curiosity observations and provide unprecedented detail of the meteorological context of Curiosity measurements. 
 
Title Cassini Saturn polar velocity fields 
Description The data comprise two 2-dimensional gridded maps of horizontal wind measurements covering the north and south polar regions of Saturn, as previously published by Antuñano et al. (2015). As fully described in that paper, these measurements were derived from sets of Cassini Orbiter Imaging Sub-System (ISS) Wide Angle Camera (WAC) and Narrow Angle Camera (NAC) images using the continuum band CB2 and CB3 filters, acquired for the northern hemisphere in June 2013 and for the southern hemisphere using WAC CB2 and CB3 images taken in October 2006 and December 2008. Additional NAC images using the CB2 and red filters taken in July 2008 were also used to analyse the southern polar vortex. The WAC images covered a region extending from a planetocentric latitude of around 60-65 degrees to each pole (apart from a segment in longitude between around 35 - 110 degrees W) with a horizontal resolution equivalent to around 0.05 degrees latitude (around 50km) per pixel, while NAC images were mostly used for the polar vortices, with a resolution equivalent to around 0.01 degrees latitude (around 10 km) per pixel. Horizontal velocities were obtained using semi-automated image correlation methods between pairs of images separated in time by intervals of approximately 1-10 hours. The correlation algorithm used pixel box sizes of 23 x 23 (in the north) or 25 x 25 (in the south), leading to a spatial resolution of the velocity vectors equivalent to around 1 degree latitude or 1000 km outside the polar vortices, reducing to around 0.2 degrees or 200 km within the polar vortices themselves. The automatically generated velocity vectors were supplemented by a small number (around 1% of the total) of vectors obtained manually from the motion of visually identified cloud tracers. The estimated measurement uncertainty on each vector was around 5-10 m/s. The original velocity vectors from Antuñano et al. (2015) were interpolated onto a regular latitude-longitude grid using convex hulls and Delauney triangulation via the QHULL routine of the Interactive Data Language (IDL). The final datasets are held on a regular grid separated by 3-4 degrees in longitude and 0.23 degrees in latitude. Data are stored as two text files, tabulating the latitude and (west) longitude of each point and the eastward and northward velocity components respectively in units of m/s. Reference: Antuñano,A., del Río-Gaztelurrutia,T., Sánchez-Lavega,A., & Hueso, R. (2015). Dynamics of Saturn's polar regions. J. Geophys. Res.: Planets, 120, 155-176. doi: 10.1002/2014JE004709 
Type Of Material Database/Collection of data 
Year Produced 2021 
Provided To Others? Yes  
Impact None as yet. 
URL https://ora.ox.ac.uk/objects/uuid:76da2bd5-ac16-4df9-b6d4-4052b99ed720
 
Title NEMESIS 
Description Development of NEMESIS radiative transfer and retrieval model. Currently used by several groups internationally and continually developing. 
Type Of Material Computer model/algorithm 
Year Produced 2021 
Provided To Others? Yes  
Impact NEMESIS has been at the heart of over 100 internationally referred papers and has enabled the research of collaborators at Oxford, Bristol, Leicester, Goddard, JPL, Paris, Bilbao and elsewhere. 
URL https://github.com/nemesiscode/radtrancode
 
Title Simulating Jupiter's weather layer: Accompanying data for Parts I and II [data-set]. 
Description This dataset contains instantaneous model states from two simulations of Jupiter's atmosphere, over 100 Earth days. The data were generated by a version of the MIT General Circulation Model (MITgcm) modified to simulate Jupiter's upper troposphere and lower stratosphere. The model simulates Jupiter's weather layer down to 18 bar at 0.7 degree horizontal resolution, with parametrizations of radiative forcing, vertical diffusion, dry convection, and ammonia and water cycles. Run B has 5.7 W/m2 heating into the bottom of the domain, while Run A does not; both are heated by the Sun from above. 
Type Of Material Database/Collection of data 
Year Produced 2018 
Provided To Others? Yes  
Impact None as yet. 
URL https://doi.org/10.5287/bodleian:PyYbbxpk2
 
Description NEMESIS Giant Planet Interpretation 
Organisation University of the Basque Country
Country Spain 
Sector Academic/University 
PI Contribution Provided NEMESIS code and training to help collaborators interpret observations of Giant Planets.
Collaborator Contribution Collaborators helped to upgrade the code to deal with their particular requirements. In addition, collaborators suggested Minnaert approach to encapsulating limb-darkening, which has proved to be extremely useful and effective in our own analyses.
Impact Several papers have come from this collaboration, in addition to code development and improvement.
Start Year 2016
 
Description Chipping Norton Astronomical Society 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach Local
Primary Audience Other audiences
Results and Impact Talk to Chipping Norton Astronomical Society on Research.
Year(s) Of Engagement Activity 2018
 
Description H2S Press Release 
Form Of Engagement Activity A press release, press conference or response to a media enquiry/interview
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Public/other audiences
Results and Impact Press release on new paper reporting the detection of H2S in the atmosphere of Uranus. Reported in national newspapers and International websites. Led to several follow-up telephone calls with website reporters and two radio interviews, one for Newstalk Radio, Dublin, and CBC, Canada.
Year(s) Of Engagement Activity 2018
URL http://www.ox.ac.uk/news/science-blog/what-do-uranuss-cloud-tops-have-common-rotten-eggs
 
Description Juno outreach talk 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach Local
Primary Audience Public/other audiences
Results and Impact Gave a talk at an event organised by "Science Oxford" describing the Juno missions and the UK's involvement in supporting ground-based observations.
Year(s) Of Engagement Activity 2016
 
Description Marlow U3A Talk 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach Local
Primary Audience Public/other audiences
Results and Impact Talk to local U3A society.
Year(s) Of Engagement Activity 2018
 
Description Pint of Science 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach Local
Primary Audience Public/other audiences
Results and Impact Talk on Cassini mission to 'Pint of Science' Event in Oxford.
Year(s) Of Engagement Activity 2018
 
Description Pint of Science 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach Local
Primary Audience Public/other audiences
Results and Impact Talk on Exoplanets to 'Pint of Science' event in Oxford.
Year(s) Of Engagement Activity 2017
 
Description Public Lecture (Tackley Oxon.) 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach Local
Primary Audience Public/other audiences
Results and Impact Around 30 people from an Oxfordshire village attended my talk on the History of Martian Climate, intended to introduce members of the public to similarities and differences between the climate history of Earth and Mars. This resulted in much interest and very positive questions and discussion, with a greater awareness and interest in ongoing and upcoming space missions, such as Insight.
Year(s) Of Engagement Activity 2018
 
Description School visit (Cheltenham College) 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach Local
Primary Audience Schools
Results and Impact At least 50 pupils in year groups from 4th form to lower 6th attended a talk on "Ice ages on Mars". The talk generated a lot of interest and lively questions from the audience, a number of which expressed an interest in pursuing courses in Physics and Mathematics at undergraduate level.
Year(s) Of Engagement Activity 2017
 
Description Talk to Astronomical Society (Farnham) 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach Regional
Primary Audience Public/other audiences
Results and Impact Talk given to Farnham Astronomical Society, attended by at least 50 people with very diverse backgrounds and interests, on the climate of extra-solar planets. Much lively discussion and questions ensued and several people reported how this had changed their views and understanding of planetary climate.
Year(s) Of Engagement Activity 2017
 
Description Talk to astronomical society (Swindon) 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach Regional
Primary Audience Public/other audiences
Results and Impact A talk on the atmospheres of Jupiter and Saturn, to inform and engage members of the public about recent research. Around 40 people attended a meeting of the Swindon Stargazers, which sparked many questions and discussion afterwards.
Year(s) Of Engagement Activity 2018
 
Description Talk to day centre (Oxford) 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach Local
Primary Audience Public/other audiences
Results and Impact Talk given to an elderly persons' day centre in Oxford on an introduction to the Solar System, attended by approximately 15 people plus carers, which sparked some lively discussion and many questions. 2 members of the audience requested further information at the end.
Year(s) Of Engagement Activity 2016