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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 NTRSDate not supplied

The Sufficient Component Cause Model Explaining Low-Dose Radiobiology through an Epidemiologic Lens

One of the major challenges in understanding space radiation-induced carcinogenesis is the uncertainty from translating radiobiological research in cellular and animal models to humans, especially at doses below 100 mSv. Biological studies have shown a host of potential outcomes at low doses in animal and cellular models. The existence of non-targeted effects as bystander and abscopal effects is well-documented from clinical research and basic science1,2,3. While some studies have shown increased effects at low doses, others have shown evidence of hormetic bystander effects, where radiation exposure may be beneficial4,5,6. Despite these varied and diverse findings, epidemiologic studies largely support the linear-no threshold (LNT) assumption used by radiation protection guidance7,8. Translational animal-to-human models have predominantly considered ratio values such as the relative biological effectiveness (RBE) and dose and dose-rate effectiveness factor (DDREF) that rely on the assumption of LNT rather than implementing specific dose-response shapes in the low-dose region, and translational cell-to-human models are uncommon. The sufficient component cause model presents an opportunity to examine biological findings at low doses from an epidemiological lens9. In this model, exposures “sufficient” to cause an outcome of interest are presented in pie charts, such that when all slices of a pie chart are fulfilled, the outcome will occur. Multiple pie charts may exist for a single outcome, illustrating individual differences9. In 1988,Greenland and Poole adapted the sufficient component cause model to incorporate interaction with other exposures (such as genetics or lifestyle factors)10. They show that a range of biological processes are possible in a population, but that an epidemiologic study will only reveal the mean outcome from the population at large10,11. Using this construct, the multiple outcomes presented in radiobiological models to date can be explained in the context of epidemiologic studies. This presentation aims to demonstrate a causal framework that can integrate radiobiological and epidemiological models to date. It is intended as a conversation starter to spur future research.

C M Milder↗
DOE OSTI2024

Dynamic Scaling Analysis of Accelerated Irradiation Testing on Additive Manufacturing Materials by Positron Annihilation

The timely applications of Additive Manufacturing (AM) materials in nuclear environments require accelerated irradiation tests, mainly ion irradiation to enable rapid prototyping. Low dose ion irradiation would cause sub-nanostructure changes by generation of lattice defects, vacancies, vacancy clusters and voids and void swelling caused by cellular dislocations. Positron Annihilation Lifetime (PAL), a novel technology, sensitive towards sub-nanostructure morphology with high accuracy (about 10-7 vacancy per atom), supported by Transition Electron Microscope (TEM) would be applied to identify the type and total size of the defects. The subsequent PAL measurements and TEM surface studies would be followed by PAL analysis that includes sophisticated trapping model. The PAS results would become an input to dynamic scaling analysis (that predicts radiation effects from low dose studies for high dose effects), which incorporate mean-field theory model. The final effect is an in-depth understanding of the microstructure evolution of AM materials under ion irradiation which can be extrapolated to the studies of neutron irradiation, since ion-irradiation takes less time and do not cause the irradiation hazard. The working hypothesis is that PAL technology, that have excellent sensitivity to low-defect concentration would help to identify ion-induced material damage on the atomic and nano-scale level, which then could be extrapolated to understand the neutron damage better.

accelerated irradiation testing↗
NASA NTRS2013

NASA Models of Space Radiation Induced Cancer, Circulatory Disease, and Central Nervous System Effects

The risks of late effects from galactic cosmic rays (GCR) and solar particle events (SPE) are potentially a limitation to long-term space travel. The late effects of highest concern have significant lethality including cancer, effects to the central nervous system (CNS), and circulatory diseases (CD). For cancer and CD the use of age and gender specific models with uncertainty assessments based on human epidemiology data for low LET radiation combined with relative biological effectiveness factors (RBEs) and dose- and dose-rate reduction effectiveness factors (DDREF) to extrapolate these results to space radiation exposures is considered the current "state-of-the-art". The revised NASA Space Risk Model (NSRM-2014) is based on recent radio-epidemiology data for cancer and CD, however a key feature of the NSRM-2014 is the formulation of particle fluence and track structure based radiation quality factors for solid cancer and leukemia risk estimates, which are distinct from the ICRP quality factors, and shown to lead to smaller uncertainties in risk estimates. Many persons exposed to radiation on earth as well as astronauts are life-time never-smokers, which is estimated to significantly modify radiation cancer and CD risk estimates. A key feature of the NASA radiation protection model is the classification of radiation workers by smoking history in setting dose limits. Possible qualitative differences between GCR and low LET radiation increase uncertainties and are not included in previous risk estimates. Two important qualitative differences are emerging from research studies. The first is the increased lethality of tumors observed in animal models compared to low LET radiation or background tumors. The second are Non- Targeted Effects (NTE), which include bystander effects and genomic instability, which has been observed in cell and animal models of cancer risks. NTE's could lead to significant changes in RBE and DDREF estimates for GCR particles, and the potential effectiveness of radiation mitigator's. The NSRM- 2014 approaches to model radiation quality dependent lethality and NTE's will be described. CNS effects include both early changes that may occur during long space missions and late effects such as Alzheimer's disease (AD). AD effects 50% of the population above age 80-yr, is a degenerative disease that worsens with time after initial onset leading to death, and has no known cure. AD is difficult to detect at early stages and the small number of low LET epidemiology studies undertaken have not identified an association with low dose radiation. However experimental studies in mice suggest GCR may lead to early onset AD. We discuss modeling approaches to consider mechanisms whereby radiation would lead to earlier onset of occurrence of AD. Biomarkers of AD include amyloid beta (A(Beta)) plaques, and neurofibrillary tangles (NFT) made up of aggregates of the hyperphosphorylated form of the micro-tubule associated, tau protein. Related markers include synaptic degeneration, dentritic spine loss, and neuronal cell loss through apoptosis. Radiation may affect these processes by causing oxidative stress, aberrant signaling following DNA damage, and chronic neuroinflammation. Cell types to be considered in multi-scale models are neurons, astrocytes, and microglia. We developed biochemical and cell kinetics models of DNA damage signaling related to glycogen synthase kinase-3(Beta) (GSK3(Beta)) and neuroinflammation, and considered multi-scale modeling approaches to develop computer simulations of cell interactions and their relationships to A(Beta) plaques and NFTs. Comparison of model results to experimental data for the age specific development of A(Beta) plaques in transgenic mice will be discussed.

Cucinotta, Francis A.↗
NASA NTRS1977

Radiological protection and medical dosimetry for the Skylab crewmen

Dosimetry results for Skylab crewmembers show that the Skylab 4 crewmen received the highest dose equivalents but remained well within the established limits for Skylab missions below the threshold of significant clinical effects. These dose equivalents apply specificially to long term effects such as general life shortening, increased neoplasm incidence, and cataract production. A Skylab crewman could fly a mission comparable to one 84-day Skylab 4 mission per year for 50 years before exceeding these career limits.

Bailey, J. V.↗
NASA NTRS1972

Solar cosmic ray hazard to interplanetary and earth-orbital space travel

A statistical treatment of the radiation hazards to astronauts due to solar cosmic ray protons is reported to determine shielding requirements for solar proton events. More recent data are incorporated into the present analysis in order to improve the accuracy of the predicted mission fluence and dose. The effects of the finite data sample are discussed. Mission fluence and dose versus shield thickness data are presented for mission lengths up to 3 years during periods of maximum and minimum solar activity; these correspond to various levels of confidence that the predicted hazard will not be exceeded.

Yucker, W. R.↗
NASA NTRS1991

Shielding analysis for a manned Mars rover powered by an SP-100 type reactor

Shield design is one of the most crucial tasks in the integration of a nuclear reactor power system to a manned Mars rover. A multilayered W and LiH shield is found to minimize the shield mass and satisfy the dose rate limit of 30 rem/y to the rover crew. The effect on dose rate of tungsten layers thicknesses and position within the lithium hydride shields is investigated. Due to the large cross section for the W (n,gamma) reaction, secondary gammas become a significant radiation source. The man-rated shield mass for the Mars rover vehicle is correlated to the reactor thermal power. The correlation fits to within 9 percent of the calculated shield mass and results in an uncertainty of below 4 percent in the overall rover mass. The shield mass varied from 8600 kg to 20580 kg for a reactor thermal power of 100 to 1000 kW(t), respectively.

Morley, Nicholas J.↗
NASA NTRS2007

Anti-radiation vaccine: Immunologically-based Prophylaxis of Acute Toxic Radiation Syndromes Associated with Long-term Space Flight

Protecting crew from ionizing radiation is a key life sciences problem for long-duration space missions. The three major sources/types of radiation are found in space: galactic cosmic rays, trapped Van Allen belt radiation, and solar particle events. All present varying degrees of hazard to crews; however, exposure to high doses of any of these types of radiation ultimately induce both acute and long-term biological effects. High doses of space radiation can lead to the development of toxicity associated with the acute radiation syndrome (ARS) which could have significant mission impact, and even render the crew incapable of performing flight duties. The creation of efficient radiation protection technologies is considered an important target in space radiobiology, immunology, biochemistry and pharmacology. Two major mechanisms of cellular, organelle, and molecular destruction as a result of radiation exposure have been identified: 1) damage induced directly by incident radiation on the macromolecules they encounter and 2) radiolysis of water and generation of secondary free radicals and reactive oxygen species (ROS), which induce chemical bond breakage, molecular substitutions, and damage to biological molecules and membranes. Free-radical scavengers and antioxidants, which neutralize the damaging activities of ROS, are effective in reducing the impact of small to moderate doses of radiation. In the case of high doses of radiation, antioxidants alone may be inadequate as a radioprotective therapy. However, it remains a valuable component of a more holistic strategy of prophylaxis and therapy. High doses of radiation directly damage biological molecules and modify chemical bond, resulting in the main pathological processes that drive the development of acute radiation syndromes (ARS). Which of two types of radiation-induced cellular lethality that ultimately develops, apoptosis or necrosis, depends on the spectrum of incident radiation, dose, dose rate, and functional conditions of impacted cells/organisms. The administration of an experimental anti-radiation vaccine may provide an immunologically based, adjunct method of prevention or prophylaxis against clinical ARS. The administration of experimental anti-radiation serum (ARS) and the use of the blood dialysis methods, such as immune plasma-sorption, may assist in the clearance of radiation-specific toxins and may enhance established strategies for the mitigation of the biological effects leading to ARS, and should be evaluated for use on exploration-class space missions.

Popov, Dmitri↗
NASA NTRS1991

Assessment of environmental effects on Space Station Freedom Electrical Power System

Analyses of EPS (electrical power system) interactions with the LEO (low earth orbit) environment are described. The results of these analyses will support EPS design so as to be compatible with the natural and induced environments and to meet power, lifetime, and performance requirements. The environmental impacts to the Space Station Freedom EPS include aerodynamic drag, atomic oxygen erosion, ultraviolet degradation, VXB effect, ionizing radiation dose and single event effects, electromagnetic interference, electrostatic discharge, plasma interactions (ion sputtering, arcing, and leakage current), meteoroid and orbital debris threats, thermal cycling effects, induced current and voltage potential differences in the SSF due to induced electric field, and contamination degradation.

Lu, Cheng-Yi↗
NASA NTRS2013

Estimating the Effects of Astronaut Career Ionizing Radiation Dose Limits on Manned Interplanetary Flight Programs

Space radiation effects mitigation has been identified as one of the highest priority technology development areas for human space flight in the NASA Strategic Space Technology Investment Plan (Dec. 2012). In this paper we review the special features of space radiation that lead to severe constraints on long-term (more than 180 days) human flight operations outside Earth's magnetosphere. We then quantify the impacts of human space radiation dose limits on spacecraft engineering design and development, flight program architecture, as well as flight program schedule and cost. A new Deep Space Habitat (DSH) concept, the hybrid inflatable habitat, is presented and shown to enable a flexible, affordable approach to long term manned interplanetary flight today.

Koontz, Steven L.↗
NASA NTRS2016

Evidence Report: Risk of Acute Radiation Syndromes Due to Solar Particle Events

Crew health and performance may be impacted by a major solar particle event (SPE), multiple SPEs, or the cumulative effect of galactic cosmic rays (GCR) and SPEs. Beyond low-Earth orbit, the protection of the Earth's magnetosphere is no longer available, such that increased shielding and protective mechanisms are necessary in order to prevent acute radiation sickness and impacts to mission success or crew survival. While operational monitoring and shielding are expected to minimize radiation exposures, there are EVA scenarios outside of low-Earth orbit where the risk of prodromal effects, including nausea, vomiting, anorexia, and fatigue, as well as skin injury and depletion of the blood-forming organs (BFO), may occur. There is a reasonable concern that a compromised immune system due to high skin doses from a SPE or due to synergistic space flight factors (e.g., microgravity) may lead to increased risk to the BFO. The primary data available at present are derived from analyses of medical patients and persons accidentally exposed to acute, high doses of low-linear energy transfer (LET) (or terrestrial) radiation. Data more specific to the space flight environment must be compiled to quantify the magnitude of increase of this risk and to develop appropriate protection strategies. In particular, information addressing the distinct differences between solar proton exposures and terrestrial exposure scenarios, including radiation quality, dose-rate effects, and non-uniform dose distributions, is required for accurate risk estimation.

Carnell, Lisa↗
NASA NTRS2020

NASA Goddard Space Flight Center’s Compendium of Radiation Effects Test Results

Total ionizing dose, displacement damage dose, and single event effects testing were performed to characterize and determine the suitability of candidate electronics for NASA space utilization. Devices tested include FETs, flash memory, FPGAs, optoelectronics, digital, analog, and bipolar devices.

Single Event Effects (SEE)↗
NASA NTRS2020

NASA Goddard Space Flight Center’s Compendium of Radiation Effects Test Results

Total ionizing dose, displacement damage dose, and single event effects testing were performed to characterize and determine the suitability of candidate electronics for NASA space utilization. Devices tested include FETs, flash memory, FPGAs, optoelectronics, digital, analog, and bipolar devices.

Single Event Effects (SEE)↗
NASA NTRSDate not supplied

NASA Goddard Space Flight Center’s Recent Radiation Effects Test Results

Total ionizing dose, displacement damage dose, and single event effects testing were performed to characterize and determine the suitability of candidate electronics for NASA space utilization. Devices tested include FPGAs, optoelectronics, digital, analog, and bipolar devices.

Single-Event Effects (SEE)↗