Dose-Effects Models for Space Radiobiology: An Overview on Dose-Effect Relationships

Space radiobiology is an interdisciplinary science that examines the biological effects of ionizing radiation on humans involved in aerospace missions. The dose-effect models are one of the relevant topics of space radiobiology. Their knowledge is crucial for optimizing radioprotection strategies (e.g., spaceship and lunar space station-shielding and lunar/Mars village design), the risk assessment of the health hazard related to human space exploration, and reducing damages induced to astronauts from galactic cosmic radiation. Dose-effect relationships describe the observed damages to normal tissues or cancer induction during and after space flights. They are developed for the various dose ranges and radiation qualities characterizing the actual and the forecast space missions [International Space Station (ISS) and solar system exploration]. Based on a Pubmed search including 53 papers reporting the collected dose-effect relationships after space missions or in ground simulations, 7 significant dose-effect relationships (e.g., eye flashes, cataract, central nervous systems, cardiovascular disease, cancer, chromosomal aberrations, and biomarkers) have been identified. For each considered effect, the absorbed dose thresholds and the uncertainties/limitations of the developed relationships are summarized and discussed. The current knowledge on this topic can benefit from further in vitro and in vivo radiobiological studies, an accurate characterization of the quality of space radiation, and the numerous experimental dose-effects data derived from the experience in the clinical use of ionizing radiation for diagnostic or treatments with doses similar to those foreseen for the future space missions. The growing number of pooled studies could improve the prediction ability of dose-effect relationships for space exposure and reduce their uncertainty level. Novel research in the field is of paramount importance to reduce damages to astronauts from cosmic radiation before Beyond Low Earth Orbit exploration in the next future. The study aims at providing an overview of the published dose-effect relationships and illustrates novel perspectives to inspire future research.

Particle Source and Loss Processes

The main sources of charged particles in the Earth’s inner magnetosphere are the Sun and the Earth’s ionosphere. Furthermore, the Galactic cosmic radiation is an important source of protons in the inner radiation belt, and roughly every 13 years, when the Earth and Jupiter are connected via the interplanetary magnetic field, a small number of electrons originating from the magnetosphere of Jupiter are observed in the near-Earth space. The energies of solar wind and ionospheric plasma particles are much smaller than the particle energies in radiation belts. A major scientific task is to understand the transport and acceleration processes leading to the observed populations up to relativistic energies. Equally important is to understand the losses of the charged particles. The great variability of the outer electron belt is a manifestation of the continuously changing balance between source and loss mechanisms, whereas the inner belt is much more stable.

Space Breeding: The Next-Generation Crops

Since the beginning of space exploration, researchers have been exploring the role of microgravity, cosmic radiation, and other aspects of the space environment on plant growth and development. To create superior crop varieties and achieve noticeable success in the space environment, several types of research have been conducted thus far. Space-grown plants have been exposed to cosmic radiation and microgravity, which has led to the generation of crop varieties with diverse genotypes and phenotypes arising from different cellular, subcellular, genomic, chromosomal, and biochemical changes. DNA damage and chromosomal aberrations due to cosmic radiation are the major factors responsible for genetic polymorphism and the generation of crops with modified genetic combinations. These changes can be used to produce next-generation crop varieties capable of surviving diverse environmental conditions. This review aims to elucidate the detailed molecular mechanisms and genetic mutations found in plants used in recent space crop projects and how these can be applied in space breeding programmes in the future.

Radio-Electronic Modules and Radiation Monitoring Systems based on Diamond Detectors

An overview of the current state and promising areas of application of semiconductor diamond detectors for creating radio-electronic monitoring systems for ionizing studies based on them is given. The main attention is paid to the creation of multifunctional space radiation monitoring systems that combine a set of diamond detectors and hardware and software tools that provide diagnostics of dose and spectrometric characteristics of various types of radiation. The data on the developed and manufactured samples of blocks and on-board control systems for cosmic and ionizing radiation are presented. The overview shows that diamond ionizing radiation detectors (IRD) are actively used in the creation of radio-electronic devices and monitoring systems for ionizing and cosmic radiation. The use of diamond IRD in combination with the developed design and technological solutions, hardware and software principles for the construction of such devices make it possible to create samples of on-board onboard avionics for separate measurement of the parameters of cosmic radiation and neutron fluxes, gamma radiation, characterized by small dimensions, high speed, hardness to radiation, mechanical and temperature influences. Multifunctional systems for ionizing radiation detection based on diamond detectors use the accumulated experience of successful development and application of discrete diamond IRD allowed us to start creating multifunctional modules and radiation monitoring systems (RMS) based on them. Theыыыыыы creation of such devices allows us to practically demonstrate the traditional advantages of discrete DIRD (high speed, the highest radiation hardness, high resistance to mechanical and thermal influences) in on-board equipment with smaller mass dimensions. The main structural and technological solutions that ensure the creation and effective functioning of RMS based on diamond IRD are the following: (1) separation the IR flow into energy sub-bands; (2) the use of software and hardware processing of data received from the IRD; (3) using a multi-detector system. Further development of research and development in these areas, in addition to solving the target tasks of radio-electronic instrumentation, will stimulate technological progress in various areas of solid-state electronics, including materials science and physics of wide-band semiconductors, the development of an experimental and technological base for the synthesis of diamond bulk crystals and multilayer structures, the creation of new technologies for ion-plasma processing of semiconductors, and a number of others.

EXPERIMENTS AT MODANE UNDERGROUND LABORATORY OR THE SWAN SONG OF RADIOCARBON ß-COUNTING BY GAS PROPORTIONAL COUNTER

ABSTRACT In 1991, a 14C ß-counting installation with four proportional CO2 gas counters was tested at the Modane underground laboratory, 1700 m below the summit of Pointe du Fréjus, reducing the muon flux to 4 muons per square meter and per day. With cosmic radiation attenuated by a factor of 2.106, the background level of the counters was reduced by 65 to 85% while its variability was reduced by a factor of 30–80 depending on the type of counter. The dating limit of these counters extends to well beyond 60,000 years.

Shielding of Cosmic Radiation by Fibrous Materials

Cosmic radiation belongs to the challenges engineers have to deal with when further developing space travel. Besides the severe risks for humans due to high-energy particles or waves, the impact of cosmic radiation on electronics and diverse materials cannot be neglected, even in microsatellites or other unmanned spacecraft. Here, we explain the different particles or waves found in cosmic radiation and their potential impact on biological and inanimate matter. We give an overview of fiber-based shielding materials, mostly applied in the form of composites, and explain why these materials can help shielding spaceships or satellites from cosmic radiation.