Planetary Radiation Belt Physics

Within the magnetic fields of planets that extend into space are regions of trapped energetic particles that are hazardous to spacecraft and humans. The way these radiation belts vary in intensity is a major focus of scientific endeavour in space science. Understanding the principles of how these dangerous regions in space behave is very important in predicting the level of hazard they pose to spacecraft.

At Earth there have been two major advances in radiation belt science: first, that intense electromagnetic waves can increase the energy of electrons to extremely high, relativistic energies via a process called cyclotron resonant wave-particle interactions, and second, that electron transport and acceleration are substantially increased by ultra low frequency (ULF) waves. These two results have transformed generally accepted ideas on the Earth's radiation belts that have lasted 40 years or more, and have spurred new satellite missions such as NASA's Van Allen Probes mission to test these ideas.

Intense electromagnetic waves are also observed inside the magnetic fields of Jupiter and Saturn which suggests that the same resonant acceleration, transport and loss processes could be important for all planetary radiation belts. The goal of this proposal is to test the hypothesis that cyclotron resonant wave-particle interactions are major electron acceleration and loss processes at Jupiter and Saturn, and play a major role in the formation of radiation belts at these planets.

The results will help determine whether resonant wave acceleration and loss of electrons is a universal process that is more widely applicable to the Sun and stars, as wells the newly discovered planets outside our Solar System. It will help set new research goals for future spacecraft missions to the planets, provide research training for young scientists, develop computer models that will be of use to the space industry in planning future missions to the outer planets, and leave a legacy of understanding that will last long after the completion of the project.

We have identified the following non-academic users who would benefit from the proposed research:

Space Agencies
Space Agencies produce models of the radiation environment for the Earth and planets for mission planning. Two new missions to Jupiter have been approved; the ESA JUICE mission scheduled for launch in 2022 and the NASA Europa Clipper mission in the early 2020s. However, data on the radiation environment are still very limited as previous missions did not sample the regions proposed for the next generation of spacecraft. Our radiation belt models for Jupiter and Saturn will provide a means to calculate the electron radiation flux for orbits which have not been sampled. The PI of this proposal has already been asked to comment on radiation dose models for Jupiter by the ESA and we will continue to discuss our data and computer codes for future collaborations.

General public
Space research is widely held to be an area that attracts young people (11-16) into Science, Technology, Engineering and Mathematics. The huge success of the BBC's major "Stargazing Live" TV programmes which included hunting for the aurora borealis and live discussions on the Sun-Earth connection (on which the PI featured) is compelling evidence of the public's interest in space research. The growing successes coming from citizen science projects (e.g. the discovery of new exoplanets) is further evidence of the appetite amongst the public for getting involved with Space science. We anticipate significant public interest in our results at the planets and propose significant outreach activities to disseminate results.

Artists
There is a growing interest in the area of "STEAM" - Science, Technology, Engineering, Art and Mathematics as reported by Prof Sir Mark Walport (http://www.bbc.co.uk/news/science-environment-40484776). A key activity happening in BAS's new Innovation Centre is regular gatherings of artists with scientists - this has already led to a "sounds of space" collaboration within the radiation belt physics group and will hopefully lead to more. Linking art and the sciences also gives another route to inspire the younger generation.