The article provides a brief description of the Liulin-MO dosimeter, which is part of the FREND (Fine Resolution Epithermal Neutron Detector) device installed on the TGO (Trace Gas Orbiter) spacecraft of the ExoMars-2016 mission. Since April 2018, TGO has been operating in orbit around Mars. Data are presented on the radiation environment in the orbit of Mars during the decline phase of the 24th cycle of solar activity and the growth phase of the 25th cycle. During the period under review, a maximum flux and dose rate due to galactic cosmic rays (GCR) were observed. Between July 2021 and March 2023, the Liulin-MO dosimeter recorded eight increases in particle fluxes and dose rates from solar proton events (SPEs). Data are presented on the radiation environment during the SPE in Mars orbit in July 2021–March 2022, when Mars was on the opposite side of the Sun from Earth. A comparison is made of particle fluxes measured in orbits around the Earth and Mars.

The dosimeter Liulin-MO for measuring the radiation environment onboard the ExoMars 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 since May 2018. The period of measurements covers the declining and minimum of the solar activity in 24th solar cycle and the inclination phase of the 25th cycle. 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 on 15-19 February 2022 is the most powerful event observed in our data. Compared are the time profiles of the particle fluxes and count rates measured by Liulin-MO and the neutron detectors of FREND during these events. The data for SEP events on TGO in July 2021-March 2022 contribute to the details for the solar activity at a time when Mars is on the opposite side of the Sun from Earth.

ExoMars is a two-launch mission undertaken by Roscosmos and European Space Agency. Trace Gas Orbiter, a satellite part of the 2016 launch carries the Fine Resolution Neutron Detector instrument as part of its payload. The instrument aims at mapping hydrogen content in the upper meter of Martian soil with spatial resolution between 60 and 200 km diameter spot. This resolution is achieved by a collimation module that limits the field of view of the instruments detectors. A dosimetry module that surveys the radiation environment in cruise to Mars and on orbit around it is another part of the instrument. This paper describes the mission and the instrument, its measurement principles and technical characteristics. We perform an initial assessment of our sensitivity and time required to achieve the mission goal. The Martian atmosphere is a parameter that needs to be considered in data analysis of a collimated neutron instrument. This factor is described in a section of this paper. Finally, the first data accumulated during cruise to Mars is presented.

Deep space manned missions are already a near future of astronautics. Radiation risk on such a long-duration journey appears to be one of the basic factors in planning and designing the mission. The paper relates to the scientific objectives and experiments for investigation of the radiation environment to be carried out during the ExoMars 2016 and 2018 joint missions of the European Space Agency (ESA) and the Federal Space Agency of Russia (Roscosmos) to Mars. The following topics are described: 1) The charged particle telescope and the experiment Liulin-MO for measuring the radiation environment on board the ExoMars 2016 Trace Gas Orbiter satellite as a part of the Fine Resolution Epithermal Neutron Detector (FREND) and 2) Liulin-ML experiment and instrument for investigating the radiation environment on Mars as a part of the active detector of neutrons and gamma rays (ADRON) on the Russian surface platform for ExoMars 2018 mission. Liulin detectors will be used in combination with the neutron detectors to study the radiation conditions both from charged particles and neutrons during the cruise phase, in Mars orbit and on the surface of Mars.

Fortunate positioning of Cluster and TC‐1 in the plasma sheet (PS) of the Earth's magnetotail has allowed studies of the current sheet (CS) structure and particle dynamics in mesoscale and microscale in both sides of the near‐Earth reconnection, which took place between 03:42 and 03:55 UT on 22 September 2004. The distinctive feature of this event was the presence of a strong negative BY field forming a “bell‐like” spatial profile with the maximum absolute value near the neutral plane. The magnitude of this BY field was almost two times larger than the interplanetary magnetic field (IMF) and therefore could not be explained solely by the IMF penetration into the magnetotail. We propose a possible intrinsic mechanism of the BY field enhancement near the neutral plane based on peculiarities of the nonadiabatic ion interaction with the thin CS. An analysis of test particle trajectories shows that in the presence of a guide field with the “bell‐like” spatial profile, a pronounced north‐south asymmetry appears in the refraction/reflection properties of nonadiabatic ions from the CS. In a region tailward of the reconnection (BZ < 0), this asymmetry results in an increase of the density of the keV ions ejected into the northern PS and moving tailward. These ions can carry the tailward current which may be responsible for the strong negative BY near the neutral plane, i.e., self‐consistent enhancement of a BY field could occur near the neutral plane.

Для оценки радиационного риска в космическом полете необходимо определить дозовые нагрузки, получаемые критическими органами тела человека. Для этой цели на борту космических кораблей проводятся эксперименты с моделями человеческого тела – фантомами, оснащенными пассивными и активными радиационными детекторами, которые измеряют распределения дозы в местах расположения критических органов. Дозиметрический телескоп “Люлин-5” создан с использованием трех кремниевых детекторов для исследования радиационной обстановки в шаровом тканеэквивалентном фантоме на Российском сегменте Международной космической станции. Цель эксперимента с прибором “Люлин-5” – исследование динамики дозы и потока частиц в фантоме, а также вариаций радиационной обстановки на МКС на продолжительных временных интервалах в зависимости от фазы цикла солнечной активности, параметров орбиты и наличия солнечных энергичных частиц. Дозиметр “Люлин-5” измеряет одновременно мощность дозы и потоки заряженных частиц на трех разных глубинах в радиальном канале фантома, а также спектр линейной передачи энергии. В данной работе представлены результаты измерений мощности дозы и потоков частиц, обусловленных различными компонентами радиационного поля на МКС, в период с июня 2007 года по декабрь 2009 года.

For estimating radiation risk in space flights it is necessary to determine radiation dose obtained by critical organs of a human body. For this purpose the experiments with human body models are carried out onboard spacecraft. These models represent phantoms equipped with passive and active radiation detectors which measure dose distributions at places of location of critical organs. The dosimetric Liulin-5 telescope is manufactured with using three silicon detectors for studying radiation conditions in the spherical tissue-equivalent phantom on the Russian segment of the International space station (ISS). The purpose of the experiment with Liulin-5 instrument is to study dynamics of the dose rate and particle flux in the phantom, as well as variations of radiation conditions on the ISS over long time intervals depending on a phase of the solar activity cycle, orbital parameters, and presence of solar energetic particles. The Liulin-5 dosimeter measures simultaneously the dose rate and fluxes of charged particles at three depths in the radial channel of the phantom, as well as the linear energy transfer. The paper presents the results of measurements of dose rate and particle fluxes caused by various radiation field components on the ISS during the period from June 2007 till December 2009.