AE9, AP9 and SPM: New Models for Specifying the Trapped Energetic Particle and Space Plasma Environment

Abstract

The radiation belts and plasma in the Earth's magnetosphere pose hazards to satellite systems which restrict design and orbit options with a resultant impact on mission performance and cost. For decades the standard space environment specification used for spacecraft design has been provided by the NASA AE8 and AP8 trapped radiation belt models. There are well-known limitations on their performance, however, and the need for a new trapped radiation and plasma model has been recognized by the engineering community for some time. To address this challenge a new set of models, denoted AE9/AP9/SPM, for energetic electrons, energetic protons and space plasma has been developed. The new models offer significant improvements including more detailed spatial resolution and the quantification of uncertainty due to both space weather and instrument errors. Fundamental to the model design, construction and operation are a number of new data sets and a novel statistical approach which captures first order temporal and spatial correlations allowing for the Monte-Carlo estimation of flux thresholds for user-specified percentile levels (e.g., 50th and 95th) over the course of the mission. An overview of the model architecture, data reduction methods, statistics algorithms, user application and initial validation is presented in this paper.

Near-Earth Space Radiation Models

“…A different approach that does not replicate actual events but which does represent temporal dynamics in a statistical manner is the Monte Carlo model, the basis of the AE9/AP9 models [33]. In a Monte Carlo model, a state vector is evolved forward in time using one of several techniques for generating surrogate time series data.…”

“…1 shows results of four models for the electron fluence at a GPS orbit. We include AE8 Min/Max [11], the GNSS model [24], a reanalysis [32] and AE9 [33], for a 10 year mission. AE8 Min and Max do not really represent error bars, since one is usually advised to add them together in some combination based on how much time the mission is expected to experience solar minimum and solar maximum conditions.…”

AE9/AP9/SPM Radiation Environment Model: User's Guide

“…fluence (time integrated flux) or total dose, may be calculated in terms of probabilities of occurrence during the course of the mission or on other timescales. Much more information about the model may be found in [Ginet, et al, 2013].…”

Benchmarking ionizing space environment models

“…The current standard models, AE8 [1] and AP8 [2], were developed by NASA at the end of the 1970s and beginning of the 1980s. Different studies have put forward their shortcomings ( [3] and [4]): inadequate resolution at low altitude, no variability on timescales less than a solar cycle, etc. To overcome these limitations a recent effort in the US has allowed to release the AE9 and AP9 specification models [4].…”

“…It turns out that the OSL DDD measures and those predicted from the ICARE-NG spectrometer measurements are within 10.7%. AP8 min [1] and OPAL [16] specification models underestimate the OSL DDD by respectively, 10.7% and 8.6% while AP9 V1.20.002 Mean [4] overestimates the OSL DDD by 42.2%. …”