High dose rates obtained outside ISS in June 2015 during SEP event

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

“…The selection method described in section 3.1 (Dachev, ) was based on the dependence of the dose rate from the particles flux. This method in this section was applied in Dachev et al, for the 21–30 June 2015 time period and also validates the selection validity.…”

“…The >100 MeV proton flux channel on GOES had only one well‐seen maximum on 29 October 2015, which is also measured with the R3DR2 instrument. The largest maximum, up to almost 3,000 μGy d −1 on 22 June 2015, was not observed in the GOES >100 MeV channel; however, if a virtual extravehicular activity (EVA) was performed during the period of this SEP maximum, the obtained doses on the skin of cosmonauts/astronauts could have reached 2.84 mGy over 6.5 h, which is identical to the average absorbed dose obtained inside of the ISS over 15 days (Dachev et al, ; Reitz et al, ).…”

“…Drastically different are the ORB and SEP sources in the left part of Figures a and b. The exact dynamics of the R3DR2 sources between 17 June and 30 June is the topic of a separate paper (Dachev et al, ). Here we mention only that the magnetic storms on 23 and 25 June and SEP events on 18, 22, and 26 June were the reasons for the drastically different ORB and SEP distributions in Figures a and b.…”

“…The descending‐orbit hourly IRB flux and dose rate values are smaller by a factor of 0.7 in comparison with the ascending ones (Dachev et al, ), which can be explained by the east‐west asymmetries of the proton fluxes in the region of the SAA (Chernykh et al, ; Wilson et al, ). The simplified explanation is that the R3DR2 detector, which was located on the left side of the ISS Zvezda module opposite the ISS vector of velocity, was shielded more by the Zvezda module body on the descending orbits from west to east drifting inner belt protons, when the ISS was in the nominal “XVV” orientation (http://spaceflight.nasa.gov/station/flash/iss_attitude.html).…”

“…The first observations of the ORB relativistic electron fluxes in the ISS laboratory module were made in 2001 with a Liulin‐E094 instrument (Dachev et al, ; Reitz et al, ). Later, ORB relativistic electron fluxes were observed with Liulin DES‐type instruments flown on the ISS and LEO satellites (Dachev et al, , ; Dachev, Horneck, et al, ; Dachev, Horneck, et al, ; Dachev, Semkova, et al, ; Dachev, Tomov, et al, ). The ORB daily dose rate was 278 μGy d −1 .…”