Observation of the radiation environment and solar energetic particle events in Mars orbit in May 2018- June 2022.

The dosimeter Liulin-MO for measuring the radiation environment onboard the ExoMars Trace Gas Orbiter (TGO) is a module of the Fine Resolution Epithermal Neutron Detector (FREND). Here we present results from measurements of the charged particle fluxes, dose rates and estimation of dose equivalent rates at ExoMars TGO Mars science orbit, provided by Liulin-MO from May 2018 to June 2022. The period of measurements covers the declining and minimum phases of the solar activity in 24th solar cycle and the rising phase of the 25th cycle. Compared are the radiation values of the galactic cosmic rays (GCR) obtained during the different phases of the solar activity. The highest values of the dose rate and flux from GCR are registered from March to August 2020. At the minimum of 24th and transition to 25th solar cycle the dose rate from GCR is 15.9 ± 1.6 µGy h-1, particle flux is 3.3 ± 0.17 cm-2s-1, dose equivalent rate is 72.3 ± 14.4 µSv h-1. Since September 2020 the dose rate and flux of GCR decrease. Particular attention is drawn to the observation of the solar energetic particle (SEP) events in July, September and October 2021, February and March 2022 as well as their effects on the radiation environment on TGO during the corresponding periods. The SEP event during15-19 February 2022 is the most powerful event observed in our data. The SEP dose during this event is 13.8 ± 1.4 mGy (in Si), the SEP dose equivalent is 21.9 ± 4.4 mSv. SEP events recorded in Mars orbit are related to coronal mass ejections (CME) observed by SOHO and STEREO A coronagraphs. Compared are the time profiles of the count rates measured by Liulin-MO, the neutron detectors of FREND and neutron detectors of the High Energy Neutron Detector (HEND) aboard Mars Odyssey during 15-19 February 2022 event. The data obtained is important for the knowledge of the radiation environment around Mars, regarding future manned and robotic flights to the planet. The data for SEP events in Mars orbit during July 2021-March 2022 contribute to the details on the solar activity at a time when Mars is on the opposite side of the Sun from Earth.

Results of long-term radiation environment monitoring by the Russian RMS system on board Zvezda module of the ISS.

The Radiation monitoring system (RMS) continuously operated in various configurations since the launch of the Zvezda module of the International Space Station (ISS). The RMS consisted of 7 units, namely: the R-16 dosimeter, 4 DB-8 dosimeters, utility and data collection units. The obtained data covers a time of 22 years. This paper analyses the radiation environment variations on board the "Zvezda" module. Variations of the onboard daily dose rate associated with changes of ISS altitude and 11-year cycle galactic cosmic rays' variations are analyzed and discussed. It is shown that the observed increase in the daily dose from 0.20 - 0.25 to 0.35 - 0.50 mGy/day is mostly due to the increase of ISS orbit altitude, resulting in a substantial increase of the dose contribution from the South Atlantic Anomaly (SAA) Region. Dose rate variations in the SAA as well as latitude and longitude dose rate distributions are discussed in detail. Analysis confirms that the well-known westward drift effect of the SAA is clearly visible from radiation dose measurements on the ISS.

The Sileye-3/Alteino experiment for the study of light flashes, radiation environment and astronaut brain activity on board the International Space Station.

In this work we describe the instrument Sileye-3/Alteino, placed on board the International Space Station in April 2002. The instrument is constituted by an Electroencephalograph and a cosmic ray silicon detector. The scientific aims include the investigation of the Light Flash phenomenon, the measurement of the radiation environment and the nuclear abundance inside the ISS and the study of astronaut brain activity in space when subject to cosmic rays.