Overview of the ISS Radiation Environment Observed during the ESA EXPOSE‐R2 Mission in 2014–2016

Abstract

The radiation risk radiometer‐dosimeter (R3D)‐R2 solid‐state detector performed radiation measurements at the European Space Agency EXPOSE‐R2 platform outside of the Russian “Zvezda” module at the International Space Station (ISS) from 24 October 2014 to 11 January 2016. The ISS orbital parameters were average altitude of 415 km and 51.6° inclination. We developed special software and used experimentally obtained formulas to determine the radiation flux‐to‐dose ratio from the R3DR2 Liulin‐type deposited‐energy spectrometer. We provide for the first time simultaneous, long‐term estimates of radiation dose external to the ISS for four source categories: (i) galactic cosmic ray particles and their secondary products; (ii) protons in the South Atlantic Anomaly region of the inner radiation belt (IRB); (iii) relativistic electrons and/or bremsstrahlung in the outer radiation belt (ORB); and (iv) solar energetic particle (SEP) events. The latter category is new in this study. Additionally, in this study, secondary particles (SP) resulting from energetic particle interaction with the detector and nearby materials are identified. These are observed continuously at high latitudes. The detected SPs are identified using the same sorting requirements as SEP protons. The IRB protons provide the highest consistent hourly dose, while the ORB electrons and SEPs provide the most extreme hourly doses. SEPs were observed 11 times during the study interval. The R3DR2 data support calculation of average equivalent doses. The 30 day and 1 year average equivalent doses are much smaller than the skin and eyes doses recommendations by the National Council on Radiation Protection (Report 132), which provides radiation protection guidance for Low Earth Orbit.

The Solar Particle Event on 10 September 2017 as observed onboard the International Space Station (ISS)

“…While the increase in dose equivalent due to the event in March 2012 inside the MATROSHKA‐R phantom was 0.480 mSv (Semkova et al, ), MSL‐RAD measured 19.5 mSv in free space (Zeitlin et al, ). As mentioned before—no event has been observed inside the ISS since May 2012—but there have been observations performed outside the ISS with the R3RD2 detector mounted behind very low shielding in the EXPOSE‐R2 facility, which showed a maximum dose rate of 87 μGy/min measured on 22 June 2015 (Dachev et al, , ). This event was not observed inside the ISS due to the rather low energy of protons from this SPE.…”

Dried Biofilms of Desert Strains of Chroococcidiopsis Survived Prolonged Exposure to Space and Mars-like Conditions in Low Earth Orbit

“…Samples in Tray 2 were exposed for 469 days to a Mars-like UV flux, l > 200 nm under a Mars-like atmosphere; the Mars-like atmosphere was kept inside the tray for 722 days until return to the Microgravity User Support Center. Samples in Tray 1 and Tray 2 were exposed to total UV (200-400 nm) fluences of about 4.58 · 10 2 kJ/m 2 and 4.92 · 10 2 kJ/m 2 , respectively, due to the presence of 0.1% neutral density filter , and about 0.5 Gy of cosmic ionizing radiation (Dachev et al, 2017). Postflight analyses were performed on 2.5-year-old samples due to the EXPOSE-R2 space mission duration (696 days from launch to landing; 900 days from launch to sample return to the lab), the time between sample preparation, integration into flight hardware, and sample distribution after return to Earth.…”

Revising More Than 20 Years of EPHIN Ion Flux Data—A New Data Product for Space Weather Applications

“…Here we use daily averaged fluxes to study long‐term variations as well as the overall contribution to the fluence of individual SEP events. The importance of such a study for the dosimetry during long space mission—especially during external vehicle activity (Dachev et al, , )—such as a potential manned mission to Mars shall be emphasized (i.e., Apáthy et al, ; Benton & Benton, ; Semkova et al, ).…”