How Much Do Solar Cycle Variations Impact Long-Term Effect Predictions at LEO?

Abstract

An 8 year long flight database from an EDAC counter implemented onboard an altimeter flying on CryoSat-2 spacecraft at 715 km altitude is analyzed to investigate on solar cycle variations impact on long term effect predictions. In-situ observations are then compared to various specification models including legacy models as well as models under developments. I. INTRODUCTION O design space missions, the current standard models, AP8 [1] and AE8 [2], are widely used in space industries. These models were developed by NASA at the end of the 1970s and beginning of the 1980s. Two versions of each model were produced (AP8 max and AP8 min, AE8 max and AE8min) to reflect solar cycle variation only at L<3 and altitudes less than 1000 km. ECSS-E10-04 standard recommend the use of AP8 min plus AE8 max to design space vehicle. This is considered to be a conservative approach because AP8 min fluxes are higher than AP8 max ones and AE8 max flux are higher than AE8 min ones. Recently two initiatives to upgrade these models are ongoing: AE9/AP9 [3] and GREEN [4] specification models. Currently, solar cycle variations are not accounted for in AE9/AP9 model while they are in GREEN. According to the variety of space environment models now available with or without solar cycle variation it is important to address the following question to help space industries in their future development: how much do solar cycle variation impact long term effect (average SEE rate, ionizing dose, and displacement damage) predictions? This paper addresses this issue for trapped protons at Low Earth Orbit (LEO). To do so, flight data from Error Detection And Correction (EDAC) counter collected over several years at LEO will be used. Then predictions obtained with AP8 min and max, AP9 mean and GREEN-p will be compared to flight data to deduce the most appropriate model to be used at LEO. In Section II, flight data are presented as well as support data necessary to perform effect calculations, in Section III model predictions will be given and in Section IV results will be discussed.

The Medium Energy Electron Telescope (MEET): Geant4‐Based Instrument Design and Analysis

“…Fluxes are estimated for the month of July 2025 during the upcoming solar maximum for a representative satellite orbit with a 94‐degree inclination and a mean altitude of 585 km. AE9 and AP9 do not currently have explicit dependence with solar cycle in current version 1.50 but have more variability of their output percentiles during solar maximum (e.g., Bourdarie et al., 2020). This representative LEO allows for quantification of trapped electrons while traversing regions in the SAA, however, high‐energy protons are also trapped in this region and could potentially contaminate electron measurements.…”