Exploiting different active silicon detectors in the International Space Station: ALTEA and DOSTEL galactic cosmic radiation (GCR) measurements

Abstract

The solar system exploration by humans requires to successfully deal with the radiation exposition issue. The scientific aspect of this issue is twofold: knowing the radiation environment the astronauts are going to face and linking radiation exposure to health risks. Here we focus on the first issue. It is generally agreed that the final tool to describe the radiation environment in a space habitat will be a model featuring the needed amount of details to perform a meaningful risk assessment. The model should also take into account the shield changes due to the movement of materials inside the habitat, which in turn produce changes in the radiation environment. This model will have to undergo a final validation with a radiation field of similar complexity. The International Space Station (ISS) is a space habitat that features a radiation environment inside which is similar to what will be found in habitats in deep space, if we use measurements acquired only during high latitude passages (where the effects of the Earth magnetic field are reduced). Active detectors, providing time information, that can easily select data from different orbital sections, are the ones best fulfilling the requirements for these kinds of measurements. The exploitation of the radiation measurements performed in the ISS by all the available instruments is therefore mandatory to provide the largest possible database to the scientific community, to be merged with detailed Computer Aided Design (CAD) models, in the quest for a full model validation. While some efforts in comparing results from multiple active detectors have been attempted, a thorough study of a procedure to merge data in a single data matrix in order to provide the best validation set for radiation environment models has never been attempted. The aim of this paper is to provide such a procedure, to apply it to two of the most performing active detector systems in the ISS: the Anomalous Long Term Effects in Astronauts (ALTEA) instrument and the DOSimetry TELescope (DOSTEL) detectors, applied in the frame of the DOSIS and DOSIS 3D project onboard the ISS and to present combined results exploiting the features of each of the two apparatuses.

Comparisons of High‐Linear Energy Transfer Spectra on the ISS and in Deep Space

“…We find that 41% of the dose and 84% of the dose equivalent come from particles with LET greater than 2.5 keV/μm in silicon. This dose share is highly consistent with results reported earlier in which ALTEA data were compared to data from the Dosimetry Telescope (DOSTEL) instrument (Narici et al, ), which measured the full LET spectrum. Similarly, when RAD surface data are integrated over the entire LET spectrum, in this case using an extrapolation to 2π, the dose rate is found to be 1.6 nGy/s, about 30% less than the reported omnidirectional rate.…”

“…Understanding the information coming from different radiation detectors positioned in different locations in the solar system (inside and outside a vessel, in the geomagnetic field, in deep space, and on a planetary surface) provides useful tools that may improve radiation countermeasure strategies. To make best use of the results from all the area detectors in the ISS, it would be necessary to have, for each new detector, an initial comparison campaign with a colocated reference detector to provide definitive cross‐calibration in the same environmental conditions, as recently described by Narici et al (). Work along these lines is in progress.…”

“…The ALTEA cosmic ray detector (Di Fino et al, , , ; Narici et al, , ; Zaconte, Casolino, Di Fino, et al, ; Zaconte, Casolino, de Santis, et al, ) acquired data onboard the ISS from 2006 to 2012 for a total of about 3.5 years. It is composed of six Silicon Detector Units (SDUs) arranged in three telescopes.…”

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

“…The ISS saw an increase of active radiation detectors applied for various research and operational purposes (Narici et al, ), thereby also increasing the data measured and available for comparison (Narici et al, ; Rios, ). In terms of dose, one of the most significant SPEs for ISS is the so‐called “Halloween event” on 28 and 29 October 2003 (GLE 65 and GLE 66), which resulted in dose values measured inside the Russian Service module by the DB‐8 detector systems (Benghin et al, , ) of 0.31–1.71 mGy (in Si) for GLE 65 and 0.67–6.82 mGy (in Si) for GLE 66.…”

Long term variations of galactic cosmic radiation on board the International Space Station, on the Moon and on the surface of Mars

“…The L-value cut enables us to generate plots for various geomagnetic shielding conditions. Similar investigations using the L-value cut as surrogate and possibility to have a free space analogue have already been presented in Narici et al (2017) and Zeitlin et al (2019b), where the high L-value dose values from the DOSTEL instruments have been compared to data from the ALTEA instrument (Narici et al, 2017) and on the other hand the ALTEA, CRaTER, and MSL-RAD LET spectra have been compared to each other (Zeitlin et al, 2019b).…”