Space Dosimetry and Space Phantom Experiments

Unlike the low-Earth orbit (LEO) project, space radiation, mainly coming from galactic cosmic radiation (GCR) and solar particle event (SPE), has been generally considered to be one of the most important health risk factors for astronauts in manned deep space exploration missions. In fact, space radiation environment in deep space is substantially different from that in low Earth orbit, in which high-energy protons and heavy nuclei provide the main contribution to the equivalent dose and health risk. Both the total equivalent dose and health risk in deep space are significantly higher than those in LEO missions, which may exceed the permissible radiation exposure limits in the career of astronauts. And, health risks from space radiation exposure remain a primary concern for manned deep space explorations. Space radiation protection is an important strategy to reduce astronauts’ risks of damage and disease induced by space radiation and ensure their health and safety in manned deep space exploration missions. Therefore, space radiation protection is considered to be an important technical problem to be solved in the further manned spaceflight project. However, the complexity and particularity of space radiation environment in manned deep space exploration missions make space radiation protection extremely difficult. Based on the analysis of space radiation environment characteristics in manned deep space exploration missions, this review systematically summarizes and analyzes the current research progresses of space radiation protection, including physical protection and biomedical protection. In general, the physical protection refers to the passive shielding and acitve shielding. The passive shielding of materials with different thickness is the simplest and feasible physical countermeasure to deal with deep space radiation, especially in the case of SPE occurrences. The passive shielding technologies were raised and reviewed from four aspects, including radiation shielding performance indexes and their applications in new material selections, manned spacecraft radiation shielding, personal radiation shielding, and astral surface soil radiation shielding. However, the passive shielding is problematic for GCR due to the penetration of primary high-energy particles, the production of secondary radiation and the mass constraints of manned spacecraft. While, active shielding, involving the generation of electromagnetic fields to deflect space radiation, is a promising and interesting technical improvement to overcome challenging technical hindrance to prevent GCR. But different kinds of active shielding technologies, such as electrostatic shielding, plasma shielding, confined and unconfined magnetic field shielding, have not been applicable in practical cases. Moreover, a series of radioprotectors and radiomitigators in the biomedical protection, including (1) antioxidants, (2) inhibitors of various pathways, (3) cytokines, chemokines, growth factors and hormones, (4) protein molecules, (5) cellular therapeutic agents, and (6) plant derived products, were also summarized and reviewed. Most radioprotectors and radiomitigators are currently being researched and developed under early preclinical phase, and have not been approved by the food and drug administrations. At the same time, the deficiency of some present radioprotectors and radiomitigators, such as the unclear biomedical mechanisms and unavoidable side-effects, limited the popularity in actual applications. In a word, the review points out that the current space radiation protection technologies still face a series of problems and challenges, and puts forward the key technologies and countermeasures of the current space radiation protection. The summary and analysis of the critical challenges and key countermeasures of space radiation protection are of great significance for the follow-up researches and provide a theoretical basis and a solution for the implementation of manned deep space exploration mission.

Shielding from space radiation, especially galactic cosmic rays (GCRs), is a significant safety challenge for future human activities in deep space. In this study, the shielding performances of potential materials [aluminum (Al), polyethylene (PE), and carbon fiber reinforced plastic (CFRP)] were investigated using Geant4 Monte Carlo simulation considering two types of biological scale parameters, the International Commission on Radiological Protection (ICRP) quality factor (QFICRP) and the plausible biological effectiveness (RBEγacute), for GCRs. The effective dose equivalent was reduced by 50% for QFICRP and 38% for RBEγacute when shielding using 20 g/cm2 of CFRP. A spacecraft made from CFRP will have a better radiation shielding performance than conventional Al-based spacecraft. The contribution of heavy ions for QFICRP based effective dose equivalent was larger by a factor of ~ 3 compared to that for RBEγacute based effective dose equivalent. The shielding materials efficiently reduced the effective dose equivalent due to ions with QFICRP > 3.36 and RBEγacute > 2.26. QFICRP and RBEγacute have advantages and disadvantages in quantifying the dose equivalent of space radiation, and the establishment of a standard parameter specified for a mixed radiation environment occupied by protons and heavy ions is necessary for practical dose assessment in deep space.

Protecting Lunar Colonies From Space Radiation

The radiation environment en route to and on Mars is dominated by sporadic Solar Energetic Particle (SEP) events and omnipresent Galactic Cosmic Rays (GCRs). Both pose significant health risks for future crewed Mars missions due to high radiation exposure, increasing the long-term cancer risk. In extreme cases, acute radiation syndromes (ARS) may occur during intense SEP events, particularly if astronauts are exposed to high-dose rates during extravehicular activities.Forecasting the occurrence and intensity of SEP events using tools such as ESPERTA, UMASEP, or REleASE is therefore crucial to provide astronauts with sufficient time to seek shelter. However, this task remains highly challenging due to the variability of SEP events, the diverse heliospheric configurations, limited data and instrumentation, as well as the complexity of prediction models. Moreover, these systems are specifically designed for the Earth or Earth-Moon system, making their applicability to Mars missions uncertain.To adress this, we present a nowcasting system for SEP events in deep space and on the Martian surface, which serves as a reliable last backup in cases where forecasts fail. Our system is developed based on dose rate measurements from the Radiation Assessment Detector (RAD) onboard the Mars Science Laboratory (MSL) during its 7-month cruise to Mars and over 12 years of operation on the Martian surface. We demonstrate that our nowcasting system provides astronauts with sufficient time to avoid both the peak radiation exposure and the majority of the cumulative dose from SEPevents. Additionally, astronauts are informed when it is safe to leave the shelter, with total shelter durations varying from a few hours to several days depending on the specific event. Our system is easy feasible, implementable in real-life scenarios, and achieves a near-zero false alarm rate both indeep space and on the Martian surface, as verified using data from MSL/RAD.

Charged particle spectra measured during the transit to Mars with the Mars Science Laboratory Radiation Assessment Detector (MSL/RAD)

The Mars Science Laboratory (MSL) payload includes the Radiation Assessment Detector (RAD) instrument, intended to fully characterize the radiation environment for the MSL mission. The RAD instrument operations concept is intended to reduce impact to spacecraft resources and effort for the MSL operations team. By design, RAD autonomously performs regular science observations without the need for frequent commanding from the Rover Compute Element (RCE). RAD operates with pre-defined sleep and observe periods, with an adjustable duty cycle for meeting power and data volume constraints during the mission. At the start of a new science observation, RAD performs a pre-observation activity to assess count rates for selected RAD detector elements. Based on this assessment, RAD can enter solar event mode, in which instrument parameters (including observation duration) are selected to more effectively characterize the environment. At the end of each observation period, RAD stores a time-tagged, fixed length science data packet in its non-volatile mass memory storage. The operating cadence is defined by adjustable parameters, also stored in non-volatile memory within the instrument. Periodically, the RCE executes an on-board sequence to transfer RAD science data packets from the instrument mass storage to the MSL downlink buffer. Infrequently, the RAD instrument operating configuration is modified by updating internal parameter tables and configuration entries.

Astronauts will be facing many risks when they are away from Earth's environment, among which radiation is one of the most vital and troublesome issues. Space radiation exposure from energetic particles of Solar Energetic Particles (SEPs) and Galactic Cosmic Rays (GCRs) can adversely impact the Central Nervous System (CNS) by inducing acute (i.e., mission critical) and chronic (i.e., post‐mission) effects, respectively. Recently, Brain Response Functions (BRFs) based on a realistic brain structure have been developed to model cosmic‐ray induced dose in the brain (Khaksarighiri et al., 2020, https://doi.org/10.1016/j.lssr.2020.07.003). In this study, to quantify the radiation induced dose and evaluate the radiation risk to the CNS of the astronauts on the surface of Mars and Moon and in deep space, we use GCR/SEP spectral models together with Mars/Moon radiation transport codes to obtain the radiation field to which astronauts are exposed, and derive the absorbed dose in the brain with BRFs. Our calculations show that GCR induced absorbed dose per month in the brain does not reach the 30‐day limit for CNS (500 mGy) as defined by NASA on either Martian or lunar surface. Based on the spectra and frequency of historical extreme SEP events recorded at Earth as ground‐level enhancement events over past five solar cycles, our results suggest that the CNS of astronauts will be generally “safe” on the Martian surface, but those on the lunar surface or in deep space may face radiation risks in their CNS if not well shielded during such extreme events.

Space radiation poses significant health risks to astronauts, including DNA damage, neurodegeneration, cardiovascular effects, and increased cancer risk. This review consolidates current knowledge on space radiation exposure, shielding technologies, and dosimetry techniques. The systematic review followed PRISMA guidelines, analysing 75 studies from Google Scholar, PubMed, and ScienceDirect. The findings highlight that galactic cosmic ray (GCRs), solar particle events (SPEs) and Van Allen Belt Radiation cause complex biological damage, requiring advanced mitigation strategies. Traditional aluminium shielding is inefficient against high-energy cosmic radiation, prompting research into hydrogen-rich polymers, nanomaterials such as boron nitride nanotubes, and in-situ resource utilization (ISRU) using regolith. Active shielding, such as magnetic and electrostatic barriers, remains experimental. Dosimetry advancements, including silicon-based detectors, Timepix pixel technology, Tissue-Equivalent Proportional Counters and AI-driven predictive models, improve radiation monitoring and risk assessment. Despite progress, challenges persist, including uncertainties in biological responses, optimizing shielding solutions, and real-time radiation exposure prediction. Future research should explore personalized medicine for radiation resilience, hybrid shielding approaches, and AI-integrated radiation risk modelling. Ensuring astronaut safety in deep-space missions requires interdisciplinary collaboration in health physics, space medicine, and engineering to develop robust radiation protection strategies.

Mars science laboratory radiation assessment detector (MSL/RAD) modeling workshop proceedings

<div class="htmlview paragraph">The ultimate limitation to manned exploration of the solar system will likely be cumulative exposure of the crews to penetrating space radiations. The two major sources of these radiations during deep-space missions are solar particle events (flares) and galactic cosmic rays. Methods to estimate crew exposures and to evaluate concomitant shield requirements for these radiation sources are currently under development. Consisting of deterministic space radiation transport computer codes and accurate models of their nuclear interaction inputs, these calculational tools are employed to estimate the composition and thicknesses of candidate shield materials required for spacecraft equipment and crew protection. In this paper, the current status of model and code development is summarized, preliminary estimates of deep-space shield requirements are presented, and an assessment of radiation protection as a potential “showstopper” for manned deep-space missions will be made.</div>

Space experiment “Cellular Responses to Radiation in Space (CellRad)”: Hardware and biological system tests

In space applications, one of the main issues is to obtain an efficient power supply. There are various types of energy sources to produce electrical power which is needed for the operation of all active spacecraft systems and subsystems. Due to the dependency of distance from the Sun, solar energy source has limited application area. On the other hand, nuclear energy sources are widely preferred to provide electrical power during many deep space and planetary science missions. Using the radioactive decay process or fission reactor, nuclear energy is converted to thermal energy. This thermal energy can be used directly for heating issues or converted to electrical energy. Thermal energy is converted to electrical energy by means of both static and dynamic thermo-electric conversion technologies. An overview of nuclear energy technologies and nuclear energy based power systems utilized in the deep space missions take place in this paper.

Characterizing the impact of emergent technologies on earth communications reliance for crewed deep space missions

During this seminar, I will talk about three of the projects I’ve been involved with at NASA in the last few years: 1. **The Human Exploration Research Analog (HERA)** is a ground-based astronaut analog mission run at NASA’s JSC in Houston to study and evaluate impacts on the crew due to isolation, remoteness, and confined habitation. NASA scientists use the collected data to develop and verify countermeasures to reduce or mitigate psychological and physiological effects for future Deep Space missions. This simulation was a 45-day trip to Mars’s moon Phobos and back with the goal of performing geological operations with complete communications delays in effect. 2. **Astrobee** is a new class of free-flying robots that operates in the interior of the International Space Station (ISS). In addition to being a research platform for microgravity free-flying robotics, Astrobee improves the efficiency of ISS operations by providing flight and payload controllers with a mobile camera and a sensor platform. 3. NASA is developing new deployable structures and material technologies for solar sail propulsion systems destined for future low-cost deep space missions. NASA’s Advanced Composite Solar Sail System (ACS3) uses composite materials in its novel, lightweight booms that deploy from a Cubesat. Data obtained from ACS3 will guide the design of future larger-scale composite solar sail systems that could be used for several deep space exploration missions.

The compilation of this Theme Issue of Philosophical Transactions of the Royal Society on the theme of Raman spectroscopic analysis of materials from extreme environments is timely for several reasons, perhaps the most significant of these being the realization in the last decade that this technique