9.2.1 Trapped radiation belt fluxes

9.2.1.1 Long term average fluxes for Earth orbits

a. For Earth orbits other than those addressed in 9.2.1.2, the standard models of the radiation belt energetic particle fluxes shall be the AE-8 and AP-8 models for electrons [RN.10] and protons [RN.11].

NOTE 1 These models are based on long term dataset averages and are most appropriate for long term cumulative effects on missions of more than 6 months duration. Statistical variation and uncertainties can be significant and are presented in Annex I.

b. They shall be used together with the geomagnetic field models shown in Table 9‑1.

c. The version of the model, i.e. solar maximum/minimum that is commensurate with the solar activity levels (MIN or MAX), of the mission phase shall be used.

d. The dates of Minima and Maxima that shall be used for solar cycles 1 to 23 and the algorithm for forecasting future Minima and Maxima are presented in Annex B.1 and Table B-1.

NOTE 1 As it is difficult to define the % of solar MIN and MAX to apply for missions not scheduled in Max or Min periods, a more conservative analysis can be obtained for all periods using AE8MAX for electron fluxes and AP8MIN for proton fluxes.

e. For analysis of the South Atlantic Anomaly (SAA), the drift of the SAA due to geomagnetic field evolution shall be included.

NOTE The translation of the orbit locations eastward in longitude 0,3° per year since 1960 prior to accessing the models provides a first approximation to this drift. [RD.14].

9.2.1.2 Long term Flux models for specific orbits[1]

9.2.1.2.1 Long term average fluxes in geostationary orbits

a. For electron fluxes in geostationary orbits (± 500 km altitude) the standard model for Earth radiation belt energetic electrons shall be the IGE 2006 average model (previously called POLE [RN.12] and Annex B.2).

b. For conservative analysis, the upper case model shall be used.

c. The mission duration parameter used with the IGE2006 model shall be rounded up to the nearest integral year.

d. For trapped proton fluxes in geostationary orbit, the trapped proton models (AP-8) specified in 9.2.1.1 shall be used.

9.2.1.2.2 Long term fluxes in GNSS/Navigation orbits

a. For electron fluxes in GPS orbits (circular, 20 000 km ± 500 km altitude; 55° Inclination) the standard model for Earth radiation belt energetic electrons shall be the ONERA MEOv2 average model (Annex B.3, [RN.13]).

b. For conservative analysis, the upper case MEOv2 model shall be used.

c. The mission duration parameter used with the MEOv2 model shall be rounded up to the nearest integral year.

d. Extrapolation of the flux spectrum from the MEOv2 model to higher energies shall use the orbit averaged spectral form provided by AE-8 MAX.

e. For trapped proton fluxes, the trapped proton models (AP-8) specified in 9.2.1.1 shall be used.

f. For orbits of altitudes between 20 500 km and 24 000 km and the Inclination range of 55° ± 5°, either the AE-8 or the MEOv2 model may be used.

NOTE If used above 20 500 km altitude the MEOv2 model can provide conservative results. More information on this model is given in Annex I.

9.2.1.3 Worst case trapped electron fluxes for internal charging analyses

a. For internal charging analyses, the FLUMIC V3 model [RN.14] as described in Annex B.4 or, for geostationary orbits, the NASA worst case model (Annex B.5) shall be used throughout the mission and the highest fluxes reported by the model used.

NOTE These electron belt models are also appropriate for short-term (from 1 day to 1 month) worst-case cumulative radiation effect analyses.

9.2.1.4 Worst case trapped proton fluxes

There is no provision in this standard related to peak or worst case trapped proton fluxes. These particles can be significant for certain applications and effects, such as sensor interference.