Electron Acceleration, Transport and Loss in Planetary Radiation Belts

How electrons are accelerated and lost inside planetary and astrophysical magnetic fields are major unresolved questions. At Earth there has been a major advance: that intense electromagnetic waves at frequencies of a few kiloHertz can accelerate electrons up to relativistic energies via cyclotron resonant wave-particle interactions. This result has transformed generally accepted ideas on the Earth's radiation belts that have lasted 40 years or more, and has spurred new satellite missions such as NASA's Van Allen Probes mission and the Japanese ERG mission to test this and related ideas.

Intense electromagnetic waves are also observed inside the magnetic fields of Jupiter and Saturn which suggests that the same resonant acceleration and loss processes that occur at Earth 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 Earth, Jupiter and Saturn, and play a major role in the formation of radiation belts at these planets.

The results of our research will help determine whether electron cyclotron resonant acceleration and loss processes are universal processes that are more widely applicable to the Sun and other astrophysical objects. It will help set new research goals for future spacecraft missions to the planets, provide research training for young scientists, develop computer models for space weather that will be of direct use to the space insurance, satellite construction, and satellite service industries, 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 insurance
One of the products of our proposed research will be an improved radiation belt model for the Earth which will better reproduce variations in the energetic electron flux during geomagnetic storms. These energetic charged particles are known to damage spacecraft. We have already spoken to Atrium Insurance and the Willis Research Network who have stated that "the possibility of using the research models to allow insurers to confirm the past existence of damaging geomagnetic conditions when handling claims for satellite damage is something that is of interest to insurers".

Satellite construction companies
Satellite construction companies use models of the radiation environment to design spacecraft. These models enable them to provide shielding for sensitive electronic components, to protect them from energetic electrons and protons which can penetrate the spacecraft and cause damage. These standard models are based on limited data at different times of the solar cycle. The radiation belt model that will be improved in the proposed research will be able to better reconstruct the Earth's radiation belts for the whole solar cycle.

Satellite service providers
Satellite service companies (e.g., TV and internet providers) have an interest in the safe and reliable operation of their spacecraft. There are a number of occasions when satellites have malfunctioned during major geomagnetic storms, for example, during the October 2003 geomagnetic storm more than 47 spacecraft reported malfunctions and one was a total loss. The work proposed in Project 1 will enable better modelling and forecasting of the relativistic electron flux experienced by the entire satellite fleet, including satellites in low Earth orbit, medium Earth orbit and geosynchronous orbit. We have developed contacts with a number of important stakeholders in the space industry including Mr D Pitchford at SES (see letter of support) and will continue to work with key stakeholders during the course of the project.

Space Agencies
Space Agencies produce models of the radiation environment for the Earth and planets for mission planning. The NASA Juno mission is due to arrive at Jupiter in 2016 and the ESA JUICE mission scheduled for launch in 2022. Data on the radiation environment at Jupiter are very limited. 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 recent 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. We anticipate significant public interest in our results at Earth and the planets and propose significant outreach activities to disseminate results.

Policy makers
Space weather is now on the UK National Risk Register and the Cabinet Office must provide contingency planning in case of an extreme event such as a space weather super-storm. The PI of this proposal is on the UK Space Environment Impacts Group which provides advice on space weather hazards to the Cabinet Office. The proposed research includes the Earth's radiation belts, which damage spacecraft, and will be of direct interest to policy makers.