Modelling the acceleration, transport and loss of radiation belt electrons to protect satellites from space weather (Rad-Sat)

Over the last 10 years the number of operational satellites in orbit has grown from 450 to more than 1300. We rely on these satellites more than ever before for a wide range of applications such as mobile phones, TV signals, internet, navigation and financial services. All these satellites must be designed to withstand the harsh radiation environment in space for a design life that can be as long as 15 years or more. Space weather events can increase electron radiation levels by five orders of magnitude in the Earth's Van Allen radiation belts causing satellite charging, disruption to satellite operations and sometimes satellite loss. For example, in 2003 it was estimated that at least 10% of all operational satellites suffered anomalies (malfunctions [1]) during a large space weather event known as the Halloween storm. It is therefore important to understand how and why radiation levels vary so much so that engineers and business can assess impact and develop mitigation measures. New results from the NASA Van Allen Probes and THEMIS satellite missions show that wave-particle interactions play the major role in the acceleration, transport and loss of high energy electrons and hence the variability of the radiation belts. This proposal brings together scientists from across the UK with stakeholders from the insurance and satellite services sector. We will process data from scientific satellites such as Van Allen Probes and THEMIS to obtain information on four very important type of waves known as magnetosonic waves, and radio-waves known as plasmaspheric hiss, lightning generated whistlers and transmitter waves. We will use data, theory and models to determine the properties of the waves and how they vary during space weather events. We will conduct studies to assess the acceleration, transport and loss of electrons due to each wave type using quasi-linear theory. We will use simulations to test whether nonlinear effects result in more particle acceleration and loss compared to quasi-linear theory. We will analyse compressional magnetosonic waves in the ultra-low frequency range and determine their effectiveness for transporting electrons across the magnetic field, and whether the transport is diffusive or not. We will incorporate the results of these studies into our state-of-the-art global radiation belt model to simulate known space weather events, and compare the results against data to highlight the importance of the waves and improve the model. We will also include local time effects and compare loss rates against data from the ground and other satellites to constrain the model. We will simulate extreme space weather events using our existing radiation belt model, and an MHD model so that we can assess the role of waves in the rapid formation of a radiation belt such as occurred in 1991 in less than 2 minutes. We will develop a stakeholder community consisting of space insurance, satellite operators and forecasters who will provide input to our research and who will use the results for risk assessment, anomaly resolution and operational planning. The project will deliver new processed data, a better forecasting capability and expertise that will support the UK Government assessment of severe space weather for the National Risk Register [2] and the growth of the satellite industry.

1. Cannon, P, S., et al. (2013), Extreme Space Weather: Impacts on Engineered Systems and Infrastructure, Royal Academy of Engineering, London, SW1A 2WH.
2. Cabinet Office, (2012), National risk register of civil emergencies, Whitehall, London SW1A 2WH, www.cabinetoffice.gov.uk.

We have identified the following non-academic users who will benefit from our research:

Space insurance

One of the outputs of our research will be a set of radiation belt models which can be used to re-create the space radiation environment for severe space weather events that damage spacecraft. In their letter of support the Atrium Space Insurance Consortium have listed 4 ways in which they will benefit, including "further information to ensure the Lloyds Realistic Disaster Scenarios are accurate and that sufficient reserves are being made to cover the potential worst case insurance losses". Space insurance may also benefit from an independent assessment of the radiation environment for anomaly resolution.

Satellite construction companies

Satellite designers must protect satellites from the harsh radiation environment in space. They use models of the radiation environment to design for the 'reasonable worst case' but there is a very large uncertainty. Our research will simulate three different types of realistic worst case events, and will provide the radiation environment for medium Earth orbit for any part of the solar cycle. Satellite designers will be able to use our results to assess the amount of shielding needed to protect satellites, particularly for electric orbit raising and medium Earth orbit where there is relatively little radiation data.

Satellite operators

Satellite operators have an interest in the safe and reliable operation of their spacecraft. Space weather events can cause satellite anomalies (malfunctions) resulting in loss of service and in some cases total satellite loss. It can also mean a delay in reaching orbit and lost revenue if an anomaly affects electric orbit raising. Our research will lead to a step-change in space weather forecasting which will provide satellite operators with space weather situation awareness. This will enable them to plan mitigating action, for example, to suspend orbit manoeuvres and software updates, to ensure more staff are available to deal with problems, to have back-up systems immediately available, and when appropriate to inform users that some services may be at risk. Satellite operators will also benefit by using the results of our case studies of particular events to help identify the cause of a satellite anomaly.

Space Weather forecasting

The UK Met Office and the European Space Agency (ESA) are developing a system of forecasting all types of space weather. Our research will include new processes into our state-of-the-art forecasting models which will enable a step-change in our forecasting capability. Subject to further agreement, the Met Office and the ESA will benefit by turning our prototype forecasting system into a fully operational system for the satellite services sector.

General public

It is widely acknowledged that space research attracts young people into Science, Technology, Engineering and Mathematics (STEM subjects). The press coverage of the UK Astronaut Tim Peak and the International Space Station, is compelling evidence of the public's interest in space research. Our dissemination activities to schools and the public will help attract young people into the STEM subjects.

Policy makers

Extreme space weather was put on the UK National Risk Register in 2012 and revised in 2014. The UK Department of Energy and Industrial Strategy (DEIS) 'owns' the risk and is developing contingency plans to mitigate the impact of severe space weather. The Department will benefit from our research which will help define scenarios for severe space weather events, and how long they may last, and will provide the radiation environment needed for further impact assessment by engineers and business. The PI (Richard Horne) is a member of the Space Environment Impacts Expert Group (SEIEG) and will be able to provide advice to Government through this Group at meetings with DEIS.