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At least 361 records · Page 20
All sourcesNASA NTRSDOE OSTI
NASA NTRS2011

Radio-Adaptive Responses of Mouse Myocardiocytes

One of the most significant occupational hazards to an astronaut is the frequent exposure to radiation. Commonly associated with increased risk for cancer related morbidity and mortality, radiation is also known to increase the risk for cardiovascular related disorders including: pericarditis, hypertension, and heart failure. It is believed that these radiation-induced disorders are a result of abnormal tissue remodeling. It is unknown whether radiation exposure promotes remodeling through fibrotic changes alone or in combination with programmed cell death. Furthermore, it is not known whether it is possible to mitigate the hazardous effects of radiation exposure. As such, we assessed the expression and mechanisms of radiation-induced tissue remodeling and potential radio-adaptive responses of p53-mediated apoptosis and fibrosis pathways along with markers for oxidative stress and inflammation in mice myocardium. 7 week old, male, C57Bl/6 mice were exposed to 6Gy (H) or 5cGy followed 24hr later with 6Gy (LH) Cs-137 gamma radiation. Mice were sacrificed and their hearts extirpated 4, 24, or 72hr after final irradiation. Real Time - Polymerase Chain Reaction was used to evaluate target genes. Pro-apoptotic genes Bad and Bax, pro-cell survival genes Bcl2 and Bcl2l2, fibrosis gene Vegfa, and oxidative stress genes Sod2 and GPx4 showed a reduced fold regulation change (Bad,-6.18; Bax,-6.94; Bcl2,-5.09; Bcl2l2,-4.03; Vegfa, -11.84; Sod2,-5.97; GPx4*,-28.72; * = Bonferroni adjusted p-value . 0.003) 4hr after H, but not after 4hr LH when compared to control. Other p53-mediated apoptosis genes Casp3, Casp9, Trp53, and Myc exhibited down-regulation but did not achieve a notable level of significance 4hr after H. 24hr after H, genetic down-regulation was no longer present compared to 24hr control. These data suggest a general reduction in genetic expression 4hrs after a high dose of gamma radiation. However, pre-exposure to 5cGy gamma radiation appears to facilitate a radio-adaptive response that mitigates the reduction in genetic expression associated with single high-dose gamma radiation exposure. This radio-adaptive response may serve as a potential countermeasure to radiation-induced myocardial remodeling and preserve the cardiovascular health of astronauts; thus, reducing the risks of human space exploration.

Seawright, John W.↗
NASA NTRS2011

Induction of a Radio-Adaptive Response by Low-dose Gamma Irradiation in Mouse Cardiomyocytes

One of the most significant occupational hazards to an astronaut is the frequent exposure to radiation. Commonly associated with increased risk for cancer related morbidity and mortality, radiation is also known to increase the risk for cardiovascular related disorders including: pericarditis, hypertension, and heart failure. It is believed that these radiation-induced disorders are a result of abnormal tissue remodeling. It is unknown whether radiation exposure promotes remodeling through fibrotic changes alone or in combination with programmed cell death. Furthermore, it is not known whether it is possible to mitigate the hazardous effects of radiation exposure. As such, we assessed the expression and mechanisms of radiation-induced tissue remodeling and potential radio-adaptive responses of p53-mediated apoptosis and fibrosis pathways along with markers for oxidative stress and inflammation in mice myocardium. 7 week old, male, C57Bl/6 mice were exposed to 6Gy (H) or 5cGy followed 24hr later with 6Gy (LH) 137Cs gamma radiation. Mice were sacrificed and their hearts extirpated 4, 24, or 72hr after final irradiation. Real Time - Polymerase Chain Reaction was used to evaluate target genes. Apoptotic genes Bad and Bax, pro-cell survival genes Bcl2 and Bcl2l2, fibrosis gene Vegfa, and oxidative stress genes Sod2 and GPx4 showed a reduced fold regulation change (Bad,-6.18; Bax,-6.94; Bcl2,-5.09; Bcl2l2,-4.03; Vegfa, -11.84; Sod2,-5.97; GPx4*,-28.72; * = Bonferroni adjusted p-value < or = 0.003) 4hr after H, but not after 4hr LH compared to control. Other p53-mediated apoptosis genes Casp3, Casp9, Trp53, and Myc exhibited down-regulation but did not achieve a notable level of significance 4hr after H. 24hr after H, genetic down-regulation was no longer present compared to 24hr control. These data suggest a general reduction in genetic expression 4hrs after a high dose of gamma radiation. However, pre-exposure to 5cGy gamma radiation appears to facilitate a radio-adaptive response that mitigates the reduction in genetic expression associated with single high-dose gamma radiation exposure. This radio-adaptive response may serve as a potential countermeasure to radiation-induced myocardial remodeling and preserve the cardiovascular health of astronauts; thus, reducing the risks of human space exploration.

Westby, Christian M.↗
NASA NTRS1999

Predicting cancer rates in astronauts from animal carcinogenesis studies and cellular markers

The radiation space environment includes particles such as protons and multiple species of heavy ions, with much of the exposure to these radiations occurring at extremely low average dose-rates. Limitations in databases needed to predict cancer hazards in human beings from such radiations are significant and currently do not provide confidence that such predictions are acceptably precise or accurate. In this article, we outline the need for animal carcinogenesis data based on a more sophisticated understanding of the dose-response relationship for induction of cancer and correlative cellular endpoints by representative space radiations. We stress the need for a model that can interrelate human and animal carcinogenesis data with cellular mechanisms. Using a broad model for dose-response patterns which we term the "subalpha-alpha-omega (SAO) model", we explore examples in the literature for radiation-induced cancer and for radiation-induced cellular events to illustrate the need for data that define the dose-response patterns more precisely over specific dose ranges, with special attention to low dose, low dose-rate exposure. We present data for multiple endpoints in cells, which vary in their radiosensitivity, that also support the proposed model. We have measured induction of complex chromosome aberrations in multiple cell types by two space radiations, Fe-ions and protons, and compared these to photons delivered at high dose-rate or low dose-rate. Our data demonstrate that at least three factors modulate the relative efficacy of Fe-ions compared to photons: (i) intrinsic radiosensitivity of irradiated cells; (ii) dose-rate; and (iii) another unspecified effect perhaps related to reparability of DNA lesions. These factors can produce respectively up to at least 7-, 6- and 3-fold variability. These data demonstrate the need to understand better the role of intrinsic radiosensitivity and dose-rate effects in mammalian cell response to ionizing radiation. Such understanding is critical in extrapolating databases between cellular response, animal carcinogenesis and human carcinogenesis, and we suggest that the SAO model is a useful tool for such extrapolation.

Non-NASA Center↗
NASA NTRS1990

Space vehicle propulsion systems - Environmental space hazards

An evaluation of hazards which exist in geo-lunar space and have the potential to negatively affect a long-term mission-oriented spacecraft systems is presented based on published data. The hazards are categorized as pervasive (radiation), incident specific (meteoroids and thermal shock), and chemically corrosive (monatomic oxygen). It appears that the number one priority should be the development of new materials; and the secondary concern should be the development of fabrication techniques for the exterior hull, so that incident specific hazards can be minimized in an active fashion. The pervasive hazard can be dealt with by exploring on-board circuit technology with ancillary monitoring systems. Effects of thermal shock on the exterior nozzle, directional gimbals, and internal combustion chamber geometry seem to need more investigation.

Bahr, G. K.↗
NASA NTRS1983

Correlated measurements of UHF radar signatures, RF radiation, and electric field changes from lightning

During Storm Hazards - 82, simultaneous measurements were made of radar echoes, fast and slow field changes and RF radiation from lightning near the Wallops Flight Facility. RF radiation and radar echoes were also obtained during periods when the NASA F106 research aircraft was struck by lightning. These data are presently being used to better understand the electrical processes which occur during strikes to the aircraft. Preliminary conclusions based on data obtained in 1982 verify that the events recorded aboard the aircraft occurred during lightning but also indicate that they occur with surprising frequency very early in the flash.

Levine, D. M.↗
NASA NTRS1983

Correlated measurements of UHF radar signatures, RF radiation and electric field changes from lightning

During Storm Hazards - 82, simultaneous measurements are made of radar echoes, fast and slow field changes and RF radiation from lightning. Radio frequency radiation and radar echoes are also obtained during periods when the research aircraft is struck by lightning. These data are presently used to better understand the electrical processes which occur during strikes to the aircraft. Preliminary conclusions verify that the events recorded aboard the aircraft occurred during lightning but also indicate that they occur with surprising frequency very early in the flash.

Levine, D. M.↗
NASA NTRS2019

Using DNA Damage to Investigate the Individual Variability of Human Sensitivity to Ionizing Radiation

High-LET ionizing radiation is a major occupational health hazard for astronauts, but risk assessment remains elusive due to limited epidemiological data. Identifying genetic factors modulating the individual radiation response may be the most effective strategy to provide individualized risk management for long-duration high-radiation missions. We have started tackling the challenge of predicting individual risks by identifying human genetic loci associated with various radiation sensitivity phenotypes in primary blood mononuclear cells from a relatively large healthy human cohort. To date, we have performed the isolation of PBMCs from 768 subjects of the same ethnicity, and irradiated PBMCs from 576 subjects with 1 and 3 particles/100µm2 of 600 MeV/n 56Fe, 350 MeV/n 40Ar and 350 MeV/n 28Si ions. The phenotypes of interest were: number of radiation-induced foci (or RIFs), CellROX oxidative stress responses and cell death, at 4h and 24h following irradiation. We have observed a significant inter-individual variability at 0 Gy between the 576 studied subjects, with a mean fold difference between the 10% lowest and highest responders of 5.6 of RIFs/cell, 7.9 in mean CellRox intensity, and 9.3 in percentage of dead cells. In order to better assess genetic factors influencing DNA repair, we used a metric previously introduced by our group to sort out radiation sensitivity phenotypes in mice: i.e. the ratio of the first to the second slope of RIFs/cell (between 0 and 1, and between 1 and 3 particle/100µm2). Preliminary data on 192 individuals showed a distribution of low-dose responders (ratio > 1) to high-dose responders (ratio < 1) at 4h of 12%, 55% and 52% respectively for Fe, Ar and Si. The average value for the first and the second slopes was very similar for the two lowest LET (0.10 [-0.26;0.58] and 0.09 [-0.45;0.41] for Ar, 0.07 [-0.27;0.38] and 0.08 [-0.19;0.42] for Si), indicating a linear dose response across both fluence. Fe showed clear saturation for the highest dose with a slope of -0.09 [-0.86;1.51] against 0.68 [-2.21;2.20] for the low dose range, which probably reflects that many PBMCs are beyond repair at the high dose. Note that other significances were found for additional factors such as BMI and age whereas none were found for sex. GWAS will be performed on all phenotypes upon completion of measurements.

Pariset, E.↗
NASA NTRS2019

Using DNA Damage to Investigate the Individual Variability of Human Sensitivity to Ionizing Radiation

High-LET ionizing radiation is a major occupational health hazard for astronauts, but risk assessment remains elusive due to limited epidemiological data. Identifying genetic factors modulating the individual radiation response may be the most effective strategy to provide individualized risk management for long-duration high-radiation missions. We have started tackling the challenge of predicting individual risks by identifying human genetic loci associated with various radiation sensitivity phenotypes in primary blood mononuclear cells from a relatively large healthy human cohort. To date, we have performed the isolation of PBMCs from 768 subjects of the same ethnicity, and irradiated PBMCs from 576 subjects with 1 and 3 particles/100µm2 of 600 MeV/n 56Fe, 350 MeV/n 40Ar and 350 MeV/n 28Si ions. The phenotypes of interest were: number of radiation-induced foci (or RIFs), CellROX oxidative stress responses and cell death, at 4h and 24h following irradiation. We have observed a significant inter-individual variability at 0 Gy between the 576 studied subjects, with a mean fold difference between the 10% lowest and highest responders of 5.6 of RIFs/cell, 7.9 in mean CellRox intensity, and 9.3 in percentage of dead cells. In order to better assess genetic factors influencing DNA repair, we used a metric previously introduced by our group to sort out radiation sensitivity phenotypes in mice: i.e. the ratio of the first to the second slope of RIFs/cell (between 0 and 1, and between 1 and 3 particle/100µm2). Preliminary data on 192 individuals showed a distribution of ?low-dose responders? (ratio > 1) to ?high-dose responders? (ratio < 1) at 4h of 12%, 55% and 52% respectively for Fe, Ar and Si. The average value for the first and the second slopes was very similar for the two lowest LET (0.10 [-0.26;0.58] and 0.09 [-0.45;0.41] for Ar, 0.07 [-0.27;0.38] and 0.08 [-0.19;0.42] for Si), indicating a linear dose response across both fluence. Fe showed clear saturation for the highest dose with a slope of -0.09 [-0.86;1.51] against 0.68 [-2.21;2.20] for the low dose range, which probably reflects that many PBMCs are beyond repair at the high dose. Note that other significances were found for additional factors ? such as BMI and age ? whereas none were found for sex. GWAS will be performed on all phenotypes upon completion of measurements.

Pariset, E.↗
NASA NTRS2017

Europa Clipper Proposed Mission - an Update

Europa, the fourth largest moon of Jupiter, is believed to be one of the best places in the solar system to look for extant life beyond Earth. The 2011 Planetary Decadal Survey, Vision and Voyages, states: “Because of this ocean’s potential suitability for life, Europa is one of the most important targets in all of planetary science.” Exploring Europa to investigate its habitability is the goal of the planned Europa Mission. This exploration is intimately tied to understanding the three “ingredients” for life: liquid water, chemistry, and energy. The Europa Mission would investigate these ingredients by comprehensively exploring Europa’s ice shell and liquid ocean interface, surface geology and surface composition to glean insight into the inner workings of this fascinating moon. In addition, a lander mission is seen as a possible future step, but current data about the Jovian radiation environment and about potential landing site hazards and potential safe landing zones is insufficient. Therefore an additional goal of the mission would be to characterize the radiation environment near Europa and investigate scientifically compelling sites for hazards, to inform a potential future landed mission.

Kirby, Karen↗
NASA NTRS1990

Radiation biology of HZE particles

The biological effects of heavy charged particle (HZE) radiation are of particular interest to travellers and planners for long duration space flights where exposure levels represent a potential health hazard. The unique feature of HZE radiation is the structured pattern of its energy deposition in targets which may be related to charge, velocity, or rate of energy loss. There are many consequences of this feature to biological endpoints when compared to effects of ionizing photons. Dose vs response and dose rate kinetics are modified, DNA and cellular repair systems are altered in their abilities to cope with damage and, the qualitative features of damage are unique for different ions. These features must be incorporated into any risk assessment system for radiation health management. HZE induced mutation, cell inactivation and altered organogenesis will be discussed emphasizing studies with the nematode Caenorhabditis elegans and cultured cells. Observations from radiobiology experiments in space will also be reviewed along with plans for future space-based studies.

Nelson, Gregory A.↗
NASA NTRS1992

Radiobiological studies with the nematode Caenorhabditis elegans. Genetic and developmental effects of high LET radiation

The biological effects of heavy charged particle (HZE) radiation are of particular interest to travellers and planners for long-duration space flights where exposure levels represent a potential health hazard. The unique feature of HZE radiation is the structured pattern of its energy deposition in targets. There are many consequences of this feature to biological endpoints when compared with effects of ionizing photons. Dose vs response and dose-rate kinetics may be modified, DNA and cellular repair systems may be altered in their abilities to cope with damage, and the qualitative features of damage may be unique for different ions. The nematode Caenorhabditis elegans is being used to address these and related questions associated with exposure to radiation. HZE-induced mutation, chromosome aberration, cell inactivation and altered organogenesis are discussed along with plans for radiobiological experiments in space.

short duration↗
NASA NTRS1990

Environmental space hazards - An overview

An overview of space hazards that exist in the geo-lunar environment is given along with specific examples of deleterious effects that can be visited upon a long-term mission-oriented spacecraft system in LEO, GEO, the intervening space, LLO, and the lunar surface. Hazards discussed are categorized as pervasive (radiation), incident specific (meteoroids, monatomic oxygen, thermal gradient and shock, and low earth orbital debris), and chemically corrosive (monatomic oxygen). It is pointed out that, while some of the difficulties encountered are common to all types of propulsion systems, in the interplanetary domain the emphasis shifts from incident specific hazards to the pervasive upsets caused by ionizing and nonionizing radiation.

Bahr, G. K.↗
NASA NTRS2023

Risk Assessment for Asteroid Impact Threat Scenarios

Asteroid impacts can cause a wide range of damage through multiple potential hazards, from localized blast waves or thermal radiation, to tsunami inundation, to global climatic effects. The level of risk posed by these hazards depends not only upon their extent and severity, but also upon the likelihood of the various damage ranges. Some consequences may be more moderate but very likely, while others may be unlikely but catastrophic. Evaluating the risk from these hazards involves substantial uncertainties across all aspects of the problem, including the properties of the asteroid itself, the specifics of its entry, and the complex high-energy damage physics involved. NASA’s Asteroid Threat Assessment Project performs Probabilistic Asteroid Impact Risk (PAIR) assessments that use fast-running entry and hazard models to evaluate millions of impact cases representing the distributions of these many uncertain parameters. This paper presents current probabilistic asteroid impact risk assessment modeling tools and approaches used for evaluating specific asteroid impact threat cases. We give an overview of the current PAIR model used to support impact threat scenarios and discuss some of the key applications of these assessment in supporting response decisions and planetary defense preparedness. We then present the results and key findings from the recent 2023 PDC hypothetical impact exercise as an example of the primary types of risk results and metrics being developed to inform and support those mitigation and response decisions.

SMD↗
NASA NTRS2015

On The Development of Additive Construction Technologies for Application to Development of Lunar/Martian Surface Structures Using In-Situ Materials

For long-duration missions on other planetary bodies, the use of in-situ materials will become increasingly critical. As man's presence on these bodies expands, so must the breadth of the structures required to accommodate them including habitats, laboratories, berms, radiation shielding for natural radiation and surface reactors, garages, solar storm shelters, greenhouses, etc. Planetary surface structure manufacturing and assembly technologies that incorporate in-situ resources provide options for autonomous, affordable, pre-positioned environments with radiation shielding features and protection from micrometeorites, exhaust plume debris, and other hazards. This is important because gamma and particle radiation constitute a serious but reducible threat to long-term survival of human beings, electronics, and other materials in space environments. Also, it is anticipated that surface structures will constitute the primary mass element of lunar or Martian launch requirements. The ability to use in-situ materials to construct these structures will provide a benefit in the reduction of up-mass that would otherwise make long-term Moon or Mars structures cost prohibitive. The ability to fabricate structures in situ brings with it the ability to repair these structures, which allows for self-sufficiency necessary for long-duration habitation. Previously, under the auspices of the MSFC In Situ Fabrication and Repair (ISFR) project and more recently, under the joint MSFC/KSC Additive Construction with Mobile Emplacement (ACME) project, the MSFC Surface Structures Group has been developing materials and construction technologies to support future planetary habitats with in situ resources. One such technology, known as Contour Crafting (additive construction), is shown in Figure 1, along with a typical structure fabricated using this technology. This paper will present the results to date of these efforts, including development of novel nozzle concepts for advanced layer deposition using the Contour Crafting process. This process, conceived initially for rapid development of cementitious structures on Earth, also lends itself exceptionally well to the automated fabrication of planetary surface structures using minimally processed regolith as aggregate, and imported binder material or binders developed from in situ materials. This process has been used successfully in the fabrication of construction elements using lunar regolith simulant and Mars regolith simulant, both with various binder materials. These binder materials have resulted from extensive evaluation and include both "imported" binder materials that might be launched from Earth as well as some binder materials that can theoretically also be derived from existing regolith materials. They were chosen to 1) reduce penetrating radiation as much as possible, primarily with hydrogen-bearing polymers, 2) attempt to provide an air-tight structure, 3) sufficiently mix and adsorb to regolith grains for strength, 4) maximize tolerance to day-night thermal cycling, 5) possibly increase electrical conductivity to dissipate any accumulated static charge, and 6) ease their application on planetary surfaces (specifically, the accommodation of reduced atmosphere and lack of heat sinks). Some of these materials have been tested with respect to radiation mitigation, micrometeorite resistance, and resistance to larger, slower-traveling pieces of regolith impinging on the surface, simulating nearby launch and landing activities. Conceptual designs for a Continuous Feedstock Delivery/Mixing System (CFDMS) will also be presented and future planned activities will be discussed as well.

Werkheiser, Niki↗
NASA NTRS1972

Space rescue considerations.

Basic objectives of rescue requirements are examined together with the hazards that would necessitate a space rescue. Such hazards include subsystem or component malfunction, crew illness or injury, enhanced radiation levels, fire, collisions, contamination, explosion or implosion, extravehicular hazard, meteoroid penetration, and operational errors. The space rescue requirement, in most cases, is one of accelerated crew retrieval. Escape and rescue systems are discussed, taking into consideration the space shuttle as an example of an earth-based rescue system. Other systems considered include a separable escape capsule and an orbital-based rescue system.

Rose, R. G.↗
NASA NTRS1988

Radiation protective structure alternatives for habitats of a lunar base research outpost

The solar and galactic cosmic radiation levels on the Moon pose a hazard to extended manned lunar missions. Lunar soil represents an available, economical material to be used for radiation shielding. Several alternatives have been suggested to use lunar soil to protect the inhabitants of a lunar base research outpost from radiation. The Universities Space Research Association has requested that a comparative analysis of the alternatives be performed, with the purpose of developing the most advantageous design. Eight alternatives have been analyzed, including an original design which was developed to satisfy the identified design criteria. The original design consists of a cylindrical module and airlock, partially buried in the lunar soil, at a depth sufficient to achieve adequate radiation shielding. The report includes descriptions of the alternatives considered, the method of analysis used, and the final design selected.

Bell, Fred J.↗
NASA NTRS2022

Enabling Innovative Research on the International Space Station to Solve the Challenges of A Human Mission to Mars: Results of the ISS4Mars International Workshops 2020–2021

During the ISS4Mars workshops in 2020–2021, personnel from the International Space Station (ISS) partner agencies convened to reflect on scenarios for how the ISS could be used and its operations possibly modified to simulate aspects of a human mission to Mars. Scientific leaders, operations experts, crewmembers, managers, and flight surgeons discussed the five hazards of human spaceflight—gravity transitions, radiation, isolation and confinement, distance from Earth, and hostile closed environments—and considered how an ISS-based analog of Mars transit could benefit assessments and mitigations of these hazards. A focused writing team then discussed the advantages and disadvantages of each approach identified by the workshop participants before developing a set of eight use cases to consider the feasibility of implementing on the ISS. The writing team also identified the prerequisites needed, including ground analog studies simulating a mission to Mars required to verify measurements and procedures, before testing could begin on the ISS. Five of the use cases were considered feasible to assess in simulations using an ISS-based analog of Mars transit if some ground rules and assumptions were met. These five use cases were Earth-independent medical operations, Earth-independent integrated operations, life support and food for a one year duration, lower-body negative pressure as a countermeasure against the effects of exposure to microgravity, and fitness levels after landing. In addition, three more extensive interventions—extended Mars surface operations, a small-volume transit analog, and artificial gravity—were deemed unfeasible for testing on the ISS. Experience gained from the five use cases executed on the ISS may help answer some of the questions in the deferred scenarios, or it may be possible to complete them on another platform (e.g. commercial space station, lunar habitat). Simulating conditions during a Mars mission on the ISS will afford higher fidelity for assessing multiple integrated hazards of human spaceflight, however, ground analogs of Mars missions can be used to ensure effective measures and experimental design before testing begins on the ISS. The strategic concepts refined as part of these workshops were brought to a multilateral forum, Mulitlateral Human Research Planel for Exploration (MHRPE), where ISS partner agencies are now discussing implementation plans to provide new opportunities to use the ISS to prepare for deep space exploration over the coming decade. In this publication we present a summary of the international strategic plans for future research that will enable operations, software, and countermeasures to be developed that will reduce the risk to humans during future crewed missions to Mars.

Human space exploration↗