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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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All sourcesNASA NTRSDOE OSTI
NASA NTRS2018

Space Radiation Induces Long Term Impact on the Cardiovascular System by the Activation of FYN Through Reactive Oxygen Species

Space radiation can damage the cardiovascular system and thus is an important health risk factor for astronauts during long-term space missions. We utilized publicly available transcriptomic data through NASA's GeneLab platform (genelab.nasa.gov) to determine cardiovascular system response to space radiation. GeneLab is an open repository that houses all NASA related omics experiments including on the International Space Station (ISS) and related radiation ground studies. We analyzed 3 datasets from GeneLab: GLDS-117 and GLDS-109, which are ground studies of cardiomyocytes followed-up for 28 days after exposure to 90cGy of proton at 1GeV and 15cGy of 56Fe at 1GeV; and GLDS-52, human endothelial cells (HUVECs) that were cultured for 10 days on the ISS. The ground studies were designed to characterize the long-term impact following space irradiation on cardiomyocytes for 5 different time points up to 28 days after irradiation. Our analysis was guided by the hypothesis that there are common persistent molecules affecting the cardiovascular system due to radiation effects during spaceflight. Endothelial cells are known to directly regulate the development and activity of cardiomyocytes, and thus their response to spaceflight should be highly correlated with cardiomyocytes. To investigate our hypothesis, we identified the molecular pathways that were modified for all time points compared across both radiation on the ground and the pathways found in HUVECs flown in the ISS. We found the following key results related to the cardiovascular systems: 1) space radiation downregulate ROS functions; and 2) the key/driving genes: FYN, LCK, AKT1 are upregulated and LYN and FOS are downregulated with FYN being the central driver/hub for the cardiovascular response to space radiation. It is worth noting the activation of FYN is a key event which prevents cardiac cell death and ROS production. From our study we thus hypothesize that a feedback loop occurs from the oxidative stress caused by space radiation that upregulates FYN which in turn reduces ROS levels and thus ROS pathways, preventing cardiomyocyte and endothelial cell death and thus protecting the cardiovascular systems. We believe that this is a novel mechanism for space radiation induced cardiovascular risk directly linking radiation ground studies to spaceflight

Beheshti, Afshin↗
NASA NTRS2022

Radiative Losses in the Chromosphere During A C-Class Flare

Context. Solar flares release an enormous amount of energy (~10(exp 32) erg) into the corona. A substantial fraction of this energy is transported to the lower atmosphere, which results in chromospheric heating. The mechanisms that transport energy to the lower solar atmosphere during a flare are still not fully understood. Aims. We aim to estimate the temporal evolution of the radiative losses in the chromosphere at the footpoints of a C-class flare, in order to set observational constraints on the electron beam parameters of a RADYN flare simulation. Methods. We estimated the radiative losses from hydrogen, and singly ionized Ca and Mg using semiempirical model atmospheres, which were inferred from a multiline inversion of observed Stokes profiles obtained with the CRISP and CHROMIS instruments on the Swedish 1-m Solar Telescope. The radiative losses were computed taking into account the effect of partial redistribution and non-local thermodynamic equilibrium. To estimate the integrated radiative losses in the chromosphere, the net cooling rates were integrated between the temperature minimum and the height where the temperature reaches 10 kK. We also compared our time series of radiative losses with those from the RADYN flare simulations. Results. We obtained a high spatial-resolution map of integrated radiative losses around the flare peak time. The stratification of the net cooling rate suggests that the Ca IR triplet lines are responsible for most of the radiative losses in the flaring atmosphere. During the flare peak time, the contribution from Ca II H and K and Mgii h and k lines are strong and comparable to the Ca IR triplet (~32kW m(exp -2)). Since our flare is a relatively weak event, the chromosphere is not heated above 11 kK, which in turn yields a subdued Lyα contribution (~7kW m(exp -2)) in the selected limits of the chromosphere. The temporal evolution of total integrated radiative losses exhibits sharply rising losses (0.4kW m(exp -2) (s(exp -1)) and a relatively slow decay (0.23kW m(exp -2) s(exp -1)). The maximum value of total radiative losses is reached around the flare peak time and can go up to 175kWm􀀀2 for a single pixel located at footpoint. After a small parameter study, we find the best model-data consistency in terms of the amplitude of radiative losses and the overall atmospheric structure with a RADYN flare simulation in the injected energy flux of 5 × 10(exp 10) erg s(exp -1) cm(exp -2).

Chromosphere↗
NASA NTRS2000

Impact of p53 status on heavy-ion radiation-induced micronuclei in circulating erythrocytes

Transgenic mice that differed in their p53 genetic status were exposed to an acute dose of highly charged and energetic (HZE) iron particle radiation. Micronuclei (MN) in two distinct populations of circulating peripheral blood erythrocytes, the immature reticulocytes (RETs) and the mature normochromatic erythrocytes (NCEs), were measured using a simple and efficient flow cytometric procedure. Our results show significant elevation in the frequency of micronucleated RETs (%MN-RETs) at 2 and 3 days post-radiation. At 3 days post-irradiation, the magnitude of the radiation-induced MN-RET was 2.3-fold higher in the irradiated p53 wild-type animals compared to the unirradiated controls, 2.5-fold higher in the p53 hemizygotes and 4.3-fold higher in the p53 nullizygotes. The persistence of this radiation-induced elevation of MN-RETs is dependent on the p53 genetic background of the animal. In the p53 wild-type and p53 hemizygotes, %MN-RETs returned to control levels by 9 days post-radiation. However, elevated levels of %MN-RETs in p53 nullizygous mice persisted beyond 56 days post-radiation. We also observed elevated MN-NCEs in the peripheral circulation after radiation, but the changes in radiation-induced levels of MN-NCEs appear dampened compared to those of the MN-RETs for all three strains of animals. These results suggest that the lack of p53 gene function may play a role in the iron particle radiation-induced genomic instability in stem cell populations in the hematopoietic system.

NASA Discipline Radiation Health↗
NASA NTRS2023

Actively Controlled Louver for Human Spacecraft Radiator Ultraviolet (UV), Dust, and Freeze Protection

The paper examines the use of actively controlled louvers for human spacecraft radiators. State of the Art (SOA) radiators were design for Low Earth Orbit (LEO) operations where Ultraviolet (UV) radiation and dust have miniscule performance impacts. However, Artemis missions to the lunar orbit or surface will expose the radiators to high dose UV radiation and dust, which can degrade the radiator coating emissivity by up to 50% and consequently reduce performance early in missions. In addition, environmental nighttime temperatures at the lunar south pole are significantly colder and linger longer than LEO, and may require up to 4 kW of heater power to prevent coolant tubes from freezing, thawing, and rupturing. Analysis showed equipping the radiators with actively controlled louvers attenuated the UV radiation and dust effects, and limited degradation to less than 10% through End of Life (EOL) of missions. Furthermore, analysis demonstrated the ability to eliminate the heater power needed for freeze protection. Louver technology is a promising solution to maintain radiator performance and integrity for Artemis missions, but heritage louvers are passively controlled and only been used on small satellites. The technology requires maturing to active control, or motor actuated, to achieve faster thermal response times. Design considerations are discussed in this paper.

Louver↗
NASA NTRSDate not supplied

Biological Space Radiation Countermeasures to Enable Long Duration Exploration Missions

NASA’s career radiation limit for astronauts is 600 mSv. Currently planned missions beyond low Earth orbit (LEO) will expose crew to at least double that amount of radiation (for Mars missions). Therefore, to enable long duration exploration, countermeasures need to be deployed to reduce the long-term health outcomes of space radiation exposure. Limitations to the ability of spacecraft to shield against the high energy charged particles of the space radiation environment necessitate alternative methods to reduce overall space radiation risk for carcinogenesis. Recent successes in the arenas of Acute Radiation Syndrome (ARS) and clinical radiotherapy have demonstrated the efficacy of compound-based/biologicals in reducing the detrimental long term health outcomes associated with space radiation exposure. In recent years, the Space Radiation Element has funded the investigation of several such compounds including Avasopasem Manganese, CDDO-Me, Metformin, and γ-tocotrienol. The demonstrated efficacy of these compounds in reducing carcinogenesis, central nervous system, and cardiovascular disease risks demonstrate the need for, and potential benefit of, a robust countermeasure identification and development program with an initial starting suite of compounds available to validate others. The authors would also like to present highlights of a recent Space Radiation Element sponsored issue of Life Sciences in Space Research entitled “Breaking the Limit” on this specific topic.

Space Radiation↗
NASA NTRS2002

Opportunities for nutritional amelioration of radiation-induced cellular damage

The closed environment and limited evasive capabilities inherent in space flight cause astronauts to be exposed to many potential harmful agents (chemical contaminants in the environment and cosmic radiation exposure). Current power systems used to achieve space flight are prohibitively expensive for supporting the weight requirements to fully shield astronauts from cosmic radiation. Therefore, radiation poses a major, currently unresolvable risk for astronauts, especially for long-duration space flights. The major detrimental radiation effects that are of primary concern for long-duration space flights are damage to the lens of the eye, damage to the immune system, damage to the central nervous system, and cancer. In addition to the direct damage to biological molecules in cells, radiation exposure induces oxidative damage. Many natural antioxidants, whether consumed before or after radiation exposure, are able to confer some level of radioprotection. In addition to achieving beneficial effects from long-known antioxidants such as vitamins E and C and folic acid, some protection is conferred by several recently discovered antioxidant molecules, such as flavonoids, epigallocatechin, and other polyphenols. Somewhat counterintuitive is the protection provided by diets containing elevated levels of omega-3 polyunsaturated fatty acids, considering they are thought to be prone to peroxidation. Even with the information we have at our disposal, it will be difficult to predict the types of dietary modifications that can best reduce the risk of radiation exposure to astronauts, those living on Earth, or those enduring diagnostic or therapeutic radiation exposure. Much more work must be done in humans, whether on Earth or, preferably, in space, before we are able to make concrete recommendations.

Review↗
NASA NTRS2004

Overview of the Martian radiation environment experiment

Space radiation presents a hazard to astronauts, particularly those journeying outside the protective influence of the geomagnetosphere. Crews on future missions to Mars will be exposed to the harsh radiation environment of deep space during the transit between Earth and Mars. Once on Mars, they will encounter radiation that is only slightly reduced, compared to free space, by the thin Martian atmosphere. NASA is obliged to minimize, where possible, the radiation exposures received by astronauts. Thus, as a precursor to eventual human exploration, it is necessary to measure the Martian radiation environment in detail. The MARIE experiment, aboard the 2001 Mars Odyssey spacecraft, is returning the first data that bear directly on this problem. Here we provide an overview of the experiment, including introductory material on space radiation and radiation dosimetry, a description of the detector, model predictions of the radiation environment at Mars, and preliminary dose-rate data obtained at Mars. c2003 COSPAR. Published by Elsevier Ltd. All rights reserved.

NASA Program Biomedical Research and Countermeasur↗
DOE OSTI2026

Strong Sensitivity of Simulated Biomass Burning Aerosol Transport and Radiative Effects Over the South Atlantic to Carbonaceous Aerosol Aging and Particle Density

Biomass burning aerosol (BBA) impacts climate through aerosol‐cloud‐radiation interactions, but models disagree on the sign and magnitude of BBA radiative effects. We quantify the sensitivity of BBA radiative effects and transport to three BBA‐relevant processes and properties: parameterized oxidative aging of organic aerosol (OA), a combined change to black carbon (BC) density and the method for calculating aerosol refractive index, and reduction in OA density. We evaluate Unified Model simulations against two aircraft campaigns from summer 2017 over the Southeast Atlantic. The model generally performs well, such that discrepancies between the observational data sets may sometimes limit the precision of the evaluation. Our newly developed aging parameterization reproduces observed OA:BC mass ratios well and allows modeled OA:BC to decrease with smoke age, but increases bias in aerosol extinction and changes the BBA radiative effect little (+0.12 W m -2 ). We calculate aerosol refractive index using either a volume‐weighted component average or the Maxwell‐Garnett (MG) mixing assumption, which represents BC as small inclusions in a host material. Compared to MG mixing, the volume‐weighted average refractive index and reduced BC density increase aerosol absorption, substantially increasing the total BBA radiative effect (+2.66 W m -2 ) and amount of BBA transported across the ocean through BC self‐lofting. Reducing OA density to better match literature values changes the total BBA radiative effect by −1.96 W m -2 . Changes to direct radiative effects exceed changes to cloud radiative effects. Our findings emphasize the sensitivity of aerosol radiative effects and transport to these processes and properties, which we suggest could be improved in climate models.

Southeast Atlantic↗
DOE OSTI2025

A kinetic line-driven radiation operator and its application to Gyrokinetics

A velocity dependent, kinetic model for line radiation is developed for continuum kinetic codes. It has been implemented in the full-f gyrokinetic code Gkeyll. The total radiation for a charge state is modeled as an advection in velocity space with a form of $\nabla_v \cdot(v\nu(v)f(v))$, guaranteeing particle conservation. The velocity dependence (in the form of an effective frequency $\nu(v)$) is found through fitting the energy loss of the operator, i.e. the second velocity moment, to the radiation data in the OpenADAS database. Therefore, each individual transition does not need to be evaluated every time step, significantly reducing the computational cost of including line radiation in a kinetic model. The dependence on velocity instead of the usual, temperature, allows the radiation to be computed from non-Maxwellian electron distribution functions: We benchmark the model against a collisional radiative model using isotropic non-Maxwellian distribution functions. A velocity dependent model of radiation can more accurately describe the radiation in the more kinetic regimes expected in reactor-scale devices. The velocity dependence qualitatively captures the quantum mechanical need for a minimum velocity before any radiation occurs.

kinetic↗
NASA NTRS2015

Preliminary Thermal Design of Cryogenic Radiation Shielding

Cryogenic Hydrogen Radiation Shielding (CHRS) is the most mass efficient material radiation shielding strategy for human spaceflight beyond low Earth orbit (LEO). Future human space flight, mission beyond LEO could exceed one year in duration. Previous radiation studies showed that in order to protect the astronauts from space radiation with an annual allowable radiation dose less than 500 mSv, 140 kgm2 of polyethylene is necessary. For a typical crew module that is 4 meter in diameter and 8 meter in length. The mass of polyethylene radiation shielding required would be more than 17,500 kg. The same radiation study found that the required hydrogen shielding for the same allowable radiation dose is 40 kgm2, and the mass of hydrogen required would be 5, 000 kg. Cryogenic hydrogen has higher densities and can be stored in relatively small containment vessels. However, the CHRS system needs a sophisticated thermal system which prevents the cryogenic hydrogen from evaporating during the mission. This study designed a cryogenic thermal system that protects the CHRS from hydrogen evaporation for one to up to three year mission. The design also includes a ground based cooling system that can subcool and freeze liquid hydrogen. The final results show that the CHRS with its required thermal protection system is nearly half of the mass of polyethylene radiation shielding.

radiation↗
NASA NTRS2015

Simulations of Cloud-Radiation Interaction Using Large-Scale Forcing Derived from the CINDY/DYNAMO Northern Sounding Array

The recently completed CINDY/DYNAMO field campaign observed two Madden-Julian oscillation (MJO) events in the equatorial Indian Ocean from October to December 2011. Prior work has indicated that the moist static energy anomalies in these events grew and were sustained to a significant extent by radiative feedbacks. We present here a study of radiative fluxes and clouds in a set of cloud-resolving simulations of these MJO events. The simulations are driven by the large-scale forcing data set derived from the DYNAMO northern sounding array observations, and carried out in a doubly periodic domain using the Weather Research and Forecasting (WRF) model. Simulated cloud properties and radiative fluxes are compared to those derived from the S-PolKa radar and satellite observations. To accommodate the uncertainty in simulated cloud microphysics, a number of single-moment (1M) and double-moment (2M) microphysical schemes in the WRF model are tested. The 1M schemes tend to underestimate radiative flux anomalies in the active phases of the MJO events, while the 2M schemes perform better, but can overestimate radiative flux anomalies. All the tested microphysics schemes exhibit biases in the shapes of the histograms of radiative fluxes and radar reflectivity. Histograms of radiative fluxes and brightness temperature indicate that radiative biases are not evenly distributed; the most significant bias occurs in rainy areas with OLR less than 150 W/ cu sq in the 2M schemes. Analysis of simulated radar reflectivities indicates that this radiative flux uncertainty is closely related to the simulated stratiform cloud coverage. Single-moment schemes underestimate stratiform cloudiness by a factor of 2, whereas 2M schemes simulate much more stratiform cloud.

Indian Ocean↗
NASA NTRS2019

Advances in Space Radiation Physics and Transport

The space radiation environment is a complex mixture of particle types and energies originating from sources inside and outside of the galaxy. These environments may be modified by the heliospheric and geomagnetic conditions as well as planetary bodies and vehicle or habitat mass shielding. In low Earth orbit (LEO), the geomagnetic field deflects a portion of the galactic cosmic rays (GCR) and all but the most intense solar particle events (SPE). There are also dynamic belts of trapped electrons and protons with low to medium energy and intense particle count rates. In deep space, the GCR exposure is more severe than in LEO and varies inversely with solar activity. Unpredictable solar storms also present an acute risk to astronauts if adequate shielding is not provided. Near planetary surfaces such as the Earth, moon or Mars, secondary particles are produced when the ambient deep space radiation environment interacts with these surfaces and/or atmospheres. These secondary particles further complicate the local radiation environment and modify the associated health risks. Characterizing the radiation fields in this vast array of scenarios and environments is a challenging task and is currently accomplished with a combination of computational models and dosimetry. The computational tools include models for the ambient space radiation environment, mass shielding geometry, and atomic and nuclear interaction parameters. These models are then coupled to a radiation transport code to describe the radiation field at the location of interest within a vehicle or habitat. Many new advances in these models have been made in the last decade, and the present review article focuses on the progress and contributions made by workers and collaborators at NASA in the same time frame. Although great progress has been made, and models continue to improve, significant gaps remain and are discussed in the context of planned future missions. Of particular interest is the juxtaposition of various review committee findings regarding the accuracy and gaps of combined space radiation environment, physics, and transport models with the progress achieved over the past decade. While current models are now fully capable of characterizing radiation environments in the broad range of forecasted mission scenarios, it should be remembered that uncertainties still remain and need to be addressed.

Space radiation↗
NASA NTRSDate not supplied

Genomic and Phenotypic Predictors of Human Ex Vivo Sensitivity to Simulated Deep Space Radiation

High-linear energy transfer (LET) ionizing radiation is a major health hazard for astronauts who will be exposed to galactic cosmic rays during upcoming lunar and Mars missions. Predicting and mitigating this risk requires understanding the factors underlying individual radiation sensitivity. We started to address this challenge by identifying the genomic and phenotypic associations with sensitivity to low and high-LET ionizing radiation ex vivo in over 750 healthy human donors. We exposed primary human blood mononuclear cells to simulated galactic cosmic ray components: 350 MeV/n 28Si, 350 MeV/n 40Ar and 600 MeV/n 56Fe particles, at 1.1 and 3 particles/100 sq.m fluences, as well as 0.1 Gy and 1 Gy doses of gamma rays, and analyzed the outcomes at 4 and 24 hours post-irradiation. We quantified DNA damage and repair responses based on 53BP1+ radiation-induced foci formation, together with oxidative stress and changes in secreted factors including immune cytokines and exosomes. We also analyzed phenotypic associations with spontaneous DNA repair foci at baseline prior to irradiation. We identified an increase in spontaneous DNA repair associated with age and latent viral infection, and observed that human spontaneous DNA repair foci at baseline can serve as a negative predictor of DNA repair and immunoregulatory cytokine production after irradiation. Furthermore, we observed a wide variability of subject- and LET-dependent radiation responses, with radiation-induced DNA repair foci increasing by dose and LET, and high-LET particle radiation resulting in more residual DNA damage compared to low-LET particles and gamma rays. We have developed multiple metrics to quantify human radiosensitivity across the spectrum of conditions. Here we present their dependence on radiation quality and phenotypic variables, including an age-dependent decrease in DNA repair after irradiation, and genomic associations with radiosensitivity based on low-coverage whole genome sequencing. We anticipate that our work will pave the way for understanding the spectrum of human radiosensitivity and identifying targets for countermeasure development to reduce DNA and cellular damage and radiation carcinogenesis during deep space exploration.

GWAS↗
NASA NTRSDate not supplied

Radiation and Fault Tolerance for Neuromorphic Computing

• The solar wind emanating from the sun is a stream of energetic electrons and protons and ions that are the primary ionizing radiation contributions. • The Earth’s magnetosphere significantly reduces radiation exposure and mutes the effects of solar flares out to 65K Km orbital altitude. • The radiation environment is highly dependent upon mission profile: for example geosynchronous orbits can see 50 times the radiation dose of a polar orbit due to reduction of atmospheric/magnetospheric shielding. • In LEO, the magnetosphere shields the Earth by creating trapped Van Allen radiation belts consisting of electrons and protons, which create a challenging radiation environment confined to specific regions. • Even for LEO, radiation dose can vary by a factor of 30 or more from a quiet sun to a solar flare. • Galactic Cosmic Rays (GCRs) are also present at very high energy, but at low rates. • Radiation effects on semiconductors are highly dependent upon particles species, energy and flux. • Therefore, radiation tolerance requirements will vary with mission profile and duration.

Space Radiation↗
NASA NTRSDate not supplied

Neurovascular effects of simulated space radiation

A major health risk for human deep space exploration is central nervous system (CNS) damage by ionizing radiation. Simulated galactic cosmic rays or their components, especially high-linear energy transfer particles such as 56Fe ions, have been shown to cause CNS damage, neuroinflammation and cognitive dysfunction in rodent models, but their effects on human CNS remain to be investigated. CNS damage from any insult, including ionizing radiation, is partially mediated by the blood-brain barrier (BBB), which regulates interactions between CNS and the rest of the body. Astrocytes are major cellular regulators of BBB permeability and also modulate neuroinflammation and neurodegeneration. However, BBB and astrocyte functions in regulating CNS responses to space radiation remain little investigated, especially in human organ analogs. Therefore, we developed and utilized a high-throughput 3D human neurovascular organ-on-a-chip model, seeded with induced pluripotent stem cell-derived cells. The effects of time course, ionizing radiation dose and dose rate were mapped by exposing the model to either acute, high dose rate radiation with simulated galactic cosmic rays or 600 MeV/n 56Fe particles, or protracted, low dose rate gamma radiation using a 57Co sealed source setup. We investigated BBB permeability, oxidative stress, cellular damage and secreted factors over the time period between 24 hours – 2 weeks after 0.1 – 0.8 Gy irradiation. We observed that ionizing radiation exposure increased BBB permeability, caused oxidative stress, damaged endothelial cells and altered expression of inflammatory cytokines with a subset of outcomes dependent on ionizing radiation dose rate. Furthermore, our results indicated that astrocyte functions were primarily deleterious at early time points and protective later after irradiation, resembling CNS responses to injury in vivo. Our findings in organ models were complemented by studies on true spaceflight using mouse spatial and single cell multi-omics, which similarly indicated spaceflight-mediated changes in astrocyte functions. In summary, our study evaluates the regulation of neurovascular responses to simulated space radiation, suggesting astrocytes as targets for countermeasures to mitigate CNS damage in deep space exploration.

Radiation↗
NASA NTRSDate not supplied

An Advanced Thermal Radiator for Global Lunar Heat Rejection

An advanced thermal radiator innovation to provide global heat rejection for Lunar exploration is described in this paper. Infrared background radiation from Lunar terrain can seriously compromise the performance of conventional thermal radiators, especially at lower latitudes. The Apollo missions boiled consumable H2O for heat rejection which would be unsustainable for long duration Lunar exploration where temperatures may exceed 250°F at the equator. The proposed innovation would provide indefinite, sustainable heat rejection for orbiting assets, rovers, landers and habitats over the entire surface of the Moon. The advanced radiator concept introduces a semi-transparent cover-glass to transmit and reflect both incident infrared radiation and solar irradiation to facilitate improved heat rejection. With sponsorship from MSFC Center Innovation Funding (CIF), two advanced radiator concepts were fabricated and evaluated inside the High Intensity Solar Environment Test (HISET) facility thermal vacuum chamber at MSFC. Using custom designed and fabricated test stands in the HISET chamber, the tests simulated both the Lunar terrestrial (inside a crater under full sun) and orbital thermal environments. A conventional radiator was also fabricated and tested under identical conditions for comparison. Test results indicate improved radiator performance (relative to conventional) in the Lunar orbital environment but the advanced radiators did not perform as well as expected in the surface environment. Correlation to thermal math models is presented and future research may consider alternate materials or designs to improve the terrestrial performance.

Thermal Control System↗
NASA NTRSDate not supplied

Genomic and phenotypic predictors of human ex vivo sensitivity to simulated deep space radiation

High-linear energy transfer (LET) ionizing radiation is a major health hazard for astronauts who will be exposed to galactic cosmic rays during upcoming lunar and Mars missions. Predicting and mitigating this risk requires understanding the factors underlying individual radiation sensitivity. We started to address this challenge by identifying the genomic and phenotypic associations with sensitivity to low and high-LET ionizing radiation ex vivo in over 750 healthy human donors. We exposed primary human blood mononuclear cells to simulated galactic cosmic ray components: 350MeV/n (28)Si, 350MeV/n (40)Ar and 600MeV/n (56)Fe particles, at 1.1 and 3 particles/100µm^(2) fluences, as well as 0.1 Gy and 1 Gy doses of gamma rays, and analyzed the outcomes at 4 and 24 hours post-irradiation. We quantified DNA damage and repair responses based on 53BP1^(+) radiation-induced foci formation, together with oxidative stress and changes in secreted factors including immune cytokines and exosomes. We also analyzed phenotypic associations with spontaneous DNA repair foci at baseline prior to irradiation. We identified an increase in spontaneous DNA repair associated with age and latent viral infection, and observed that human spontaneous DNA repair foci at baseline can serve as a negative predictor of DNA repair and immunoregulatory cytokine production after irradiation. Furthermore, we observed a wide variability of subject- and LET-dependent radiation responses, with radiation-induced DNA repair foci increasing by dose and LET, and high-LET particle radiation resulting in more residual DNA damage compared to low-LET particles and gamma rays. We have developed multiple metrics to quantify human radiosensitivity across the spectrum of conditions. Here we present their dependence on radiation quality and phenotypic variables, including an age-dependent decrease in DNA repair after irradiation, and genomic associations with radiosensitivity based on low-coverage whole genome sequencing. We anticipate that our work will pave the way for understanding the spectrum of human radiosensitivity and identifying targets for countermeasure development to reduce DNA and cellular damage and radiation carcinogenesis during deep space exploration.

GWAS↗
NASA NTRSDate not supplied

Neuro-behavioral Consequences of Low Dose Radiation Social Isolation and Sex Differences in the Longevity MCAT Mouse Model

The physiological responses to spaceflight elicit wide-ranging consequences and resemble aspects of aging on Earth. Previous studies have shown that oxidative damage via reactive oxygen species (ROS), contributes to aging-related pathologies. Our study uses 1-year old C57BL/6NJ male and female mice (astronaut-relevant age) that underwent exposure to 0.5 gray of gamma radiation together with social isolation and were euthanized 12 weeks after. We used the longevity MCAT mouse model in which human catalase is overexpressed in the mitochondria, for ROS quenching. We aimed to determine whether in older mice quenching ROS, will mitigate the neuro-behavioral consequences of low dose ionizing radiation and/or social isolation and whether the outcomes will differ in males and females. We have performed five mission relevant behavioral tests which focused on performance, memory, physical stance, and stress. We have detected both sex and radiation effects; the older females look physically better are faster and perform better almost in all behavioral tests compared to their male counterparts. On the other hand, they are more sensitive to low dose radiation in many cases, in some cases this effect was indeed mitigated in the MCAT mice, pointing out to the importance of ROS in response to radiation stress and social isolation. We have measured plasma (7- and 90-days post radiation), cytokines, corticosterone and hippocampal cytokine and microglial activation at the end of the experiment. We saw significant changes in the plasma markers due to radiation, sex, and genotype in both short and long post radiation period and detected long term sex and radiation effects in the brain. Our focus is now on applying advanced statistical modeling to corelate the behavioral tests with our recent molecular findings to look for specific biomarkers that could predict behavioral deficits.

radiation↗