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Health risks from radiation exposure in space are an important factor for astronauts’ safety as they venture on long-duration missions to the Moon or Mars. It is important to assess the radiation level inside the human brain to evaluate the possible hazardous effects on the central nervous system especially during solar energetic particle (SEP) events. We use a realistic model of the head/brain structure and calculate the radiation deposit therein by realistic SEP events, also under various shielding scenarios. We then determine the relation between the radiation dose deposited in different parts of the brain and the properties of the SEP events and obtain some simple and ready-to-use functions which can be used to quickly and reliably forecast the event dose in the brain. Such a novel tool can be used from fast nowcasting of the consequences of SEP events to optimization of shielding systems and other mitigation strategies of astronauts in space.

Potential deleterious health effects to astronauts induced by space radiation is one of the most important long-term risks for human space missions, especially future planetary missions to Mars which require a return-trip duration of about 3 years with current propulsion technology. In preparation for future human exploration, the Radiation Assessment Detector (RAD) was designed to detect and analyze the most biologically hazardous energetic particle radiation on the Martian surface as part of the Mars Science Laboratory (MSL) mission. RAD has measured the deep space radiation field within the spacecraft during the cruise to Mars and the cosmic ray induced energetic particle radiation on Mars since Curiosity’s landing in August 2012. These first-ever surface radiation data have been continuously providing a unique and direct assessment of the radiation environment on Mars. We analyze the temporal variation of the Galactic Cosmic Ray (GCR) radiation and the observed Solar Energetic Particle (SEP) events measured by RAD from the launch of MSL until December 2020, i.e., from the pre-maximum of solar cycle 24 throughout its solar minimum until the initial year of Cycle 25. Over the long term, the Mars’s surface GCR radiation increased by about 50% due to the declining solar activity and the weakening heliospheric magnetic field. At different time scales in a shorter term, RAD also detected dynamic variations in the radiation field on Mars. We present and quantify the temporal changes of the radiation field which are mainly caused by: (a) heliospheric influences which include both temporary impacts by solar transients and the long-term solar cycle evolution, (b) atmospheric changes which include the Martian daily thermal tide and seasonal CO2 cycle as well as the altitude change of the rover, (c) topographical changes along the rover path-way causing addition structural shielding and finally (d) solar particle events which occur sporadically and may significantly enhance the radiation within a short time period. Quantification of the variation allows the estimation of the accumulated radiation for a return trip to the surface of Mars under various conditions. The accumulated GCR dose equivalent, via a Hohmann transfer, is about 0.65±0.24 sievert and 1.59±0.12 sievert during solar maximum and minimum periods, respectively. The shielding of the GCR radiation by heliospheric magnetic fields during solar maximum periods is rather efficient in reducing the total GCR-induced radiation for a Mars mission, by more than 50%. However, further contributions by SEPs must also be taken into account. In the future, with advanced nuclear thrusters via a fast transfer, we estimate that the total GCR dose equivalent can be reduced to about 0.2 sievert and 0.5 sievert during solar maximum and minimum periods respectively. In addition, we also examined factors which may further reduce the radiation dose in space and on Mars and discuss the many uncertainties in the interpreting the biological effect based on the current measurement.

On 28 October 2021, solar eruptions caused intense and long‐lasting solar energetic particle (SEP) flux enhancements observed by spacecraft located over a wide longitudinal range in the heliosphere. SEPs arriving at Earth caused the 73rd ground level enhancement (GLE) event recorded by ground‐based neutron monitors. In particular, this is also the first GLE event seen on the surface of three planetary bodies, Earth, Moon, and Mars, by particle and radiation detectors as shown in this study. We derive the event‐integrated proton spectrum from measurements by near‐Earth spacecraft and predict the lunar and martian surface radiation levels using particle transport models. Event doses at the lunar and martian surfaces of previous GLE events are also modeled and compared with the current event. This statistical and comparative study advances our understanding of potential radiation risks induced by extreme SEP events for future human explorations of the Moon and Mars. Plain Language Summary Human beings are considering going back to the Moon and eventually to Mars within the next decades. However, we are still facing one major hurdle “space radiation” which is a significant and unavoidable risk for crews' health, especially for long‐term stays at future lunar or martian stations. In particular, sporadic solar energetic particles (SEPs) generated via extreme solar eruptions may enhance the lunar or martian surface radiation levels to potentially hazardous values. Recent lunar and martian surface and orbital radiation detectors have advanced our understanding of the radiation environment of both planetary bodies. On 28 October 2021 a SEP event occurred and had energies high enough to trigger ground‐level‐enhancement (GLE) events on the surface of Earth, the Moon, and Mars. Combining both measurements and modeling approaches, we study this first GLE event seen on three planetary surfaces and demonstrate its potential SEP radiation risk to humans on the Moon and Mars together with the results of previous GLE events. Key Points This is the first ground level enhancement event simultaneously measured on Earth, Moon, and Mars We analyze the radiation measurements at 3 locations and compare with our model predictions based on detected solar energetic particle (SEP) flux We show that extreme SEP events can induce much higher (∼100 times) radiation doses on the Moon than on Mars

In this paper, we design an ultra-thin broadband transparent absorber based on indium tin oxide (ITO) film, and we choose polymethyl methacrylate (PMMA) high-transmittance dielectric sheet instead of the traditional dielectric sheet and polyethylene glycol terephthalate (PET) as the ITO film substrate. Simulation results indicate that the absorber achieves more than 90% absorption for positively incident electromagnetic waves in the broadband range of 5–21.15 GHz with a fractional bandwidth (FBW) of 123.5% and a thickness of 6.3 mm (0.105 λL, where λL is the wavelength at the lowest frequency). Meanwhile, this paper introduces the interference theory to explain the broadband absorption mechanism of the absorber, which makes up for the defect that the equivalent circuit model (ECM) method cannot analyze the oblique incidence electromagnetic wave. This paper also compares the HFSS simulation results, ECM theoretical values, and interference theoretical values under positively incident electromagnetic waves to clarify the advantages of interference theory in the design of wave absorbers.

On 2022‐02‐15, solar eruptions caused one of the most intensive Solar Particle Events (SPEs) in Solar Cycle 25 observed at various heliospheric locations. This study focuses on the enhancements of energetic proton flux observed by multiple detectors located at the orbit and on the surface of Mars. We carry out the first analysis by the Mars Energetic Particle Analyzer (MEPA) instrument on board the Chinese Tianwen‐1 spacecraft (TW‐1) at Mars orbit which also serves to validate the instrument's capability to measure protons of up to 100 MeV. We reconstruct the event spectrum up to 1 GeV and further model the event doses at Mars's orbit and surface which are then validated against the corresponding dosimetry data. Our study utilizes all available radiation detectors at Mars, advances our understanding of Mars's radiation environment induced by large SPEs, and emphasizes the necessity of continuous and synergistic radiation monitoring at Mars. Plain Language Summary There is a growing interest in exploring Mars in the coming decades. However, a significant obstacle that remains is the presence of space radiation, which poses a considerable and unavoidable threat to crew health, especially during long‐term stays in future Martian habitats. Of particular concern are sporadic energetic particle events caused by strong solar eruptions, which can increase radiation levels in deep space and near Mars to potentially dangerous levels. Notably, a SEP event on 15 February 2022 has caused the first significant radiation enhancement at Mars in Solar Cycle 25 as observed by ESA's Trace Gas Orbiter, Chinese Tianwen‐1 orbiter as well as NASA's Mars Atmosphere and Volatile Evolution spacecraft and the Curiosity rover. By combining data from measurement and modeling techniques, we reconstruct the energy spectrum of this SEP event to understand the potential radiation hazards at Mars. Key Points A major solar particle event (SPE) was simultaneously measured by multiple detectors both on the surface and in orbit of Mars The first analysis of a SPE at Mars measured by the Tianwen‐1 Mars orbiter serves to verify its capacity in high‐energy particle detection We compare the radiation measurements, both on the surface and in orbit of Mars, with results derived from data‐based models

Immune checkpoint blockade (ICB) therapy has emerged as a new therapeutic paradigm for a variety of advanced cancers, but wide clinical application is hindered by low response rate. Here we use a peptide-based, biomimetic, self-assembly strategy to generate a nanoparticle, TPM1, for binding PD-L1 on tumour cell surface. Upon binding with PD-L1, TPM1 transforms into fibrillar networks in situ to facilitate the aggregation of both bound and unbound PD-L1, thereby resulting in the blockade of the PD-1/PD-L1 pathway. Characterizations of TPM1 manifest a prolonged retention in tumour ( > 7 days) and anti-cancer effects associated with reinvigorating CD8 + T cells in multiple mice tumour models. Our results thus hint TPM1 as a potential strategy for enhancing the ICB efficacy. Immune checkpoint blockade therapy such as anti-PD-L1 is efficient for treating specific cancer types, but poor response rates remain a caveat. Here the authors generate a peptide-based, self-assembly nanomaterial that binds and aggregates PD-L1 as a fibrillar networks to enhance the anti-tumour efficacy of anti-PD-L1 in multiple mouse tumour models.

One of the very common in situ signatures of interplanetary coronal mass ejections (ICMEs), as well as other interplanetary transients, are Forbush decreases (FDs), i.e. short-term reductions in the galactic cosmic ray (GCR) flux. A two-step FD is often regarded as a textbook example, which presumably owes its specific morphology to the fact that the measuring instrument passed through the ICME head on, encountering first the shock front (if developed), then the sheath, and finally the CME magnetic structure. The interaction of GCRs and the shock/sheath region, as well as the CME magnetic structure, occurs all the way from Sun to Earth, therefore, FDs are expected to reflect the evolutionary properties of CMEs and their sheaths. We apply modeling to different ICME regions in order to obtain a generic two-step FD profile, which qualitatively agrees with our current observation-based understanding of FDs. We next adapt the models for energy dependence to enable comparison with different GCR measurement instruments (as they measure in different particle energy ranges). We test these modeling efforts against a set of multi-spacecraft observations of the same event, using the Forbush decrease model for the expanding flux rope ( ForbMod ). We find a reasonable agreement of the ForbMod model for the GCR depression in the CME magnetic structure with multi-spacecraft measurements, indicating that modeled FDs reflect well the CME evolution.

The Moon lacks a global magnetic field and atmosphere, leaving its surface been directly exposed to high‐energy cosmic radiation. Sporadic Solar Particle Events are sources of a significant radiation exposure, potentially posing serious threats to the health of astronauts exploring the Moon. In this paper, we use the Radiation Environment and Dose at the Moon (REDMoon) model based on GEometry And Tracking (GEANT4) Monte‐Carlo method to calculate the body effective dose induced by 262 large historical SEP events on the Moon under different shielding depths which can result from the lunar regolith shielding and/or additional aluminum shielding. We calculate and compare the contributions of different particles from or produced by SEPs to the total body effective dose. Additionally, we develop empirical functions to rapidly assess SEP‐induced effective dose on the Moon under different shielding scenarios.

Chang’E 4 is the first mission to the far side of the Moon and consists of a lander, a rover, and a relay spacecraft. Lander and rover were launched at 18:23 UTC on December 7, 2018 and landed in the von Kármán crater at 02:26 UTC on January 3, 2019. Here we describe the Lunar Lander Neutron & Dosimetry experiment (LND) which is part of the Chang’E 4 Lander scientific payload. Its chief scientific goal is to obtain first active dosimetric measurements on the surface of the Moon. LND also provides observations of fast neutrons which are a result of the interaction of high-energy particle radiation with the lunar regolith and of their thermalized counterpart, thermal neutrons, which are a sensitive indicator of subsurface water content.

Solar Energetic Particles (SEP) are one of the major sources of the Martian radiation environment. It is important to understand the SEP‐induced Martian radiation environment for future human habitats on Mars. Due to the lack of a global intrinsic magnetic field, Solar Energetic Particles (SEPs) can directly propagate through and interact with its atmosphere before reaching the surface and subsurface of Mars. Mars has many high mountains and low‐altitude craters where the atmospheric thickness can be more than 10 times different than one another. The SEP‐induced surface radiation level may therefore be very different from one location to another. We thus consider the influence of the atmospheric depths on the Martian radiation levels including the absorbed dose, dose equivalent, and (human‐)body effective dose induced by SEPs at varying heights above and below the Martian surface. The state‐of‐the‐art Atmospheric Radiation Interaction Simulator based on GEometry And Tracking Monte‐Carlo method has been employed for simulating particle interactions with the Martian atmosphere and terrain. We find that even the thinnest Martian atmosphere reduces radiation dose from that in deep space by at least 65%, and the shielding effect increases for denser atmosphere. Furthermore, we present a method to quickly forecast the SEP‐induced radiation in different regions of Mars with different surface pressures.