EVENT-BASED ELECTRON BELT RADIATION STORM ENVIRONMENTS MODELLING (ARTES AT 4A.090)

Description

The objective of the activity is to develop a statistical radiation environment model by focussing on the distributions of electronbelt variabilities resulting from geomagnetic storms. Such a model shall capture extremes of the environment over shorter timescales as well as variability between solar cycles with respect to current models based on long term average environments.Targeted Improvements:30% reduction in the safety margin by having a more precise knowledge of this environment.Description:Small satellite constellations at 2,000 km will be flying through proton and electron radiation belts and, due to the radiation levels encountered, may experience loss of control, generating risk of collisions and problems during de-orbiting phases. Geostationary satellites using electric propulsion for orbit raising consume most of their radiation budget before arriving on station. Furthermore, radiation shielding is at risk of decreasing in the presence of strong commercial pressure to reduce satellite mass, making it even more import and to improve knowledge of the radiation environment and the accuracy of associated models. Variations in the event-based electron belt radiation storm environment can reach several orders of magnitude and are driven by solar phenomena such as persistent heliospheric structures. Models used to specify this environment are principally empirical in origin, providing either long-term mean or short-term percentile or worst-case outputs, which covers the two extreme timescales. However, these models do not capture the fluctuations explicitly, and instead rely on regression to the mean or highest values, an approach with results bounded/limited by observations. The models can be excessively conservative over longer timescales. On the contrary, Solar Energetic Particle (SEP) specification model fluxes are based on confidence levels derived by statistically modelling radiation storms both in time and magnitude. Better specification of these environments/timescales would reduce uncertainties and hence the design margins for telecommunication satellites. SEP models allow users to derive environments for the long- and short-term during solar maximum and minimum.This activity shallproduce an analogue event-based model for the outer Van Allen belt, leveraging existing tools and methodologies. Due to the spatialvariations seen in the Van Allen belts, this approach is intrinsically more complex than its SEP counterpart. Identifying radiationbelt events relative to the quiet time, functions capturing the variations of the events in both time and magnitude shall be explored, exploiting existing capabilities from SEP modelling. These events can be mapped to the spatial extent of the radiation belt with electron flux spectra, which is the most novel aspect of this activity. The final model will be made readily implantable in existingtools, like SPENVIS, OMERE or Network-of-Models, and will provide outputs relevant for accumulated (dose) effects and short-term effects (nominally internal charging) as a function of orbit, energy, confidence, and solar cycle phase. This model will be compared to other models and implemented in existing tools.Procurement Policy: C(2) = A relevant participation (in terms of quality and quantity) of non-primes (incl. SMEs) is required. For additional information please go to:http://www.esa.int/About_Us/Business_with_ESA/Small_and_Medium_Sized_En…

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