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.

Several space experiments are planned for probing the soil composition of the Moon and Mars onboard Luna 25, Luna 27, and ExoMars 2020 landers using instruments of the ADRON series. The method of active neutron and gamma ray logging, the main goals and objectives of these experiments, the content of the equipment, and the design and electronics of these instruments are described.

This article presents a description of the experiment on the Joint Institute for Nuclear Research (JINR) Phasotron proton beam for a laboratory model of a space instrument for the gamma spectrometry of celestial bodies based on the method of tagged charged particles of galactic cosmic rays. One feature of the experiment is the use of a p-type high-purity germanium semiconductor detector as part of the model.

The laboratory demonstration of the space experiment was conducted at Joint Institute for Nuclear Research with a new type of planetary gamma-ray spectrometer (GRS-TCP) suite including a gamma-ray detector and a charged particle detector combined in coincidence mode. The proposed GRS prototype can select gamma-ray photons with time tags of charged particles of Galactic cosmic rays (GCR) from a predefined solid angle on the sky. It allows to collect gamma-rays only from a local spot on the irradiated surface under the rover or lander and rejects gamma-ray detections from the surrounding area/spacecraft body significantly improving signal-to-noise ratio. The main objective of this laboratory demonstration was to study the capability of this method to distinguish between local spots with different elemental compositions that could be passed by the rover along its traverse. For this purpose, the soil sample simulants corresponding to the different types of Martian regolith identified by Curiosity rover were created and tested by laboratory measurements. It was experimentally shown that our method of spectroscopy of gamma-rays with tags of charged particles could reliably detect local variations of the planetary regolith.

This paper presents the results of the analysis of data from the BTN-Neutron space experiment carried out onboard the Russian module Zvezda, which is part of the International Space Station . The long observation period from 2008 to 2019 covers the end of the 23rd and almost all of the 24th solar cycle. This made it possible to estimate the amplitude of long-period variations of the neutron background outside the ISS due to solar modulation of galactic cosmic rays. For equatorial regions with a high geomagnetic-cutoff index, it does not exceed 10%, while the neutron background changes by almost 1.5–2 times in high-latitude regions around the Earth’s magnetic poles and the South Atlantic Magnetic Anomaly. For the periods of minimum and maximum solar activity within the 24th solar cycle, according to the BTN-Neutron experiment, maps of the distribution of the neutron-component power were constructed and the average neutron-dose rates that the cosmonauts could receive during these periods were estimated. It was shown that, for maximum and minimum solar activity, the average neutron dose rate varies from 25 to 35 µSv/day for neutrons with energies below 15 MeV.

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.

n Erratum to this paper has been published: https://doi.org/10.1134/S0010952522330012

An Erratum to this paper has been published: https://doi.org/10.1134/S0010952522330012

Studies of hydrogen deposition in the shallow Martian subsurface have been conducted by two neutron and one gamma-ray detectors in the past and provided global hydrogen maps (Boynton et al., 2002; Feldman et al., 2002; Mitrofanov et al., 2002). It is known from these maps that hydrogen is most abundant in the polar permafrost areas compared to the equatorial band where frozen water is not stable on the surface. However, the spatial resolution of hundreds of kilometres typical for these maps does not allow for detection of local hydrogen-rich features that can be associated with geological structures. The FREND neutron telescope (Mitrofanov et al., 2018) onboard ExoMars TGO (Vago et al., 2015) is capable of a much better spatial resolution for mapping neutron emission of Mars. In this Report we present an analysis of the most intriguing local area of highly suppressed neutron emission in the vicinity of the Martian equator, which coincides with Candor Chaos in the central area of Valles Marineris, thought to be promising for testing water ice (Gourronc et al., 2014). Provided such suppression would be interpreted as the evidence for very high content of hydrogen in the soil, the mean water equivalent hydrogen value in the local suppression area should be as large as 40.3 wt%. This finding is thought to be uncommon for equatorial regions, but is probably associated with particular geomorphological conditions inside Valles Marineris.

As recent studies onboard various spacecraft have shown, one unresolved technical problem of manned interplanetary flights at the moment is the high radiation background of interplanetary space, which, as in the case of a manned mission to Mars, can be critically dangerous for the crew. Work on this topic is being carried out by all space agencies. One such space experiment is represented by the BTN-Neutron experiment onboard the Russian section of the International Space Station ( ISS ). The main result of the work was the construction of the BTN-M2 instrument for creating effective radiation protection onboard prospective manned spacecraft, creating an engineering model of the radiation background both inside and outside the ISS , and for registration of γ rays and neutrons during solar flares and cosmic γ-ray bursts.

The article presents results of ground calibrations of the FREND neutron telescope installed onboard the TGO spacecraft of the Russian-European ExoMars project. The main goal of the FREND space experiment is to measure hydrogen content in the subsurface layer of Mars to a depth of 1 m. High resolution maps of water mass fraction in the regolith are constructed based on these measurements. During ground physical calibrations, assessments of effective areas and measurements of angular sensitivity functions were obtained for each of the five FREND detectors. We demonstrate that FREND measurement characteristics correspond to its declared scientific goals and allow detecting and investigating local areas with enhanced water/water ice concertation on the subsurface of Mars with high spatial resolution of up to 60–200 km.

The article presents main scientific tasks and description of the ADRON-LR instrument (active detector of neutrons and gamma-rays), which was developed at the IKI RAS for the Russian lunar landing mission Luna-25. The measurement technique and results are presented of ground-based experiments with models of lunar soil with different hydrogen content, which confirmed high sensitivity of the method of active neutron sensing for evaluation of water content and major elements of planetary matter.

The laboratory demonstration of a space experiment implementing spectrometry of planetary gamma-rays with tags of Galactic Cosmic Rays (GCR) was conducted at Joint Institute for Nuclear Research. The main objective of these efforts was to study the capability of this method to search for heterogeneities in the analog of planetary soil and to compare it with capability of the standard gamma-ray spectroscopy. It was experimentally shown that the method of spectroscopy of gamma-rays with tags demonstrates much higher confidence to search variations of amounts of the most widespread metals, like Al, Fe and Ti, in the planetary regoliths. The numerical simulation of the laboratory experiment shows a very good agreement with observations. It is proved that gamma-ray spectrometry with tags is a perspective method for future space missions to explore the Moon, Mars and another celestial bodies with thin atmosphere or without it.

A new concept of a space experiment with a γ-ray spectrometer onboard a mobile spacecraft has been proposed for studying the elemental composition of the Moon, Mars, and other celestial bodies without an atmosphere or with a thin atmosphere using the method of tagged charged particles of galactic cosmic rays. This technique makes it possible to eliminate almost fully the background of γ-radiation from the spacecraft with the instrument installed onboard and significantly increase the spatial resolution for studying the elemental composition of matter along the mobile spacecraft trajectory.

An updated set of goals and objectives for the Mercury Gamma and Neutron Spectrometer (MGNS) are presented based on the most recent findings of the MESSENGER mission. The updated design of MGNS with the new CeBr 3 crystal for detection of gamma-ray along with its benefits for the detection of 40 K and K/Th ratio are discussed. MGNS will then be capable of measuring the elemental composition of shallow subsurface in order to empirically evaluate the fittest model on the origin of Mercury, as well as the presence of possible water ice deposits on the permanently shadowed polar craters on the planet. We present the results of the first measurements in space performed during the instrument commissioning phase and during the first Earth flyby which occurred in April 2020.