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NASA NTRS1991

Compensation of distributed delays in integrated communication and control systems

The concept, analysis, implementation, and verification of a method for compensating delays that are distributed between the sensors, controller, and actuators within a control loop are discussed. With the objective of mitigating the detrimental effects of these network induced delays, a predictor-controller algorithm was formulated and analyzed. Robustness of the delay compensation algorithm was investigated relative to parametric uncertainties in plant modeling. The delay compensator was experimentally verified on an IEEE 802.4 network testbed for velocity control of a DC servomotor.

Ray, Asok↗

NASA NTRS2007

Nuclear Fragmentation Processes Relevant for Human Space Radiation Protection

Space radiation from cosmic ray particles is one of the main challenges for human space explorations such-as a moon base or a trip to Mars. Models have been developed in order to predict the radiation exposure to astronauts and to evaluate the effectiveness of different shielding materials, and a key ingredient in these models is the physics of nuclear fragmentations. We have developed a semi-analytical method to determine which partial cross sections of nuclear fragmentations most affect the radiation dose behind shielding materials due to exposure to galactic cosmic rays. The cross sections thus determined will require more theoretical and/or experimental studies in order for us to better predict, reduce and mitigate the radiation exposure in human space explorations.

Lin, Zi-Wei↗

NASA NTRS2005

An Algorithm for the Transport of Anisotropic Neutrons

One major obstacle to human space exploration is the possible limitations imposed by the adverse effect of long-term exposure to the space environment. Even before human spaceflight began, the potentially brief exposure of astronauts to the very intense random solar particle events (SPE) were of great concern. A new challenge appears in deep space exploration from exposure to the low-intensity heavy-ion flux of the galactic cosmic rays (GCR) since the missions are of long duration and the accumulated GCR exposures can be high. Because cancer induction rates increase behind low to rather large thicknesses of aluminum shielding, according to available biological data on mammalian exposures to GCR like ions, the shield requirements for a Mars mission are prohibitively expensive in terms of mission launch costs. Therefore, a critical issue in the Human Exploration and Development of Space enterprise is cost effective mitigation of risk associated with ionizing radiation exposure. In order to estimate astronaut risk to GCR exposure and associated cancer risks and health hazards, it is necessary to do shield material studies. To determine an optimum radiation shield material it is necessary to understand nuclear interaction processes such as fragmentation and secondary particle production which is a function of energy dependent cross sections. This requires knowledge of material transmission characteristics either through laboratory testing or improved theoretical modeling. Here ion beam transport theory is of importance in that testing of materials in the laboratory environment generated by particle accelerators is a necessary step in materials development and evaluation for space use. The approximations used in solving the Boltzmann transport equation for the space setting are often not sufficient for laboratory work and those issues are a major emphasis of the present work.

Tweed, J.↗

NASA NTRS2010

Active Dust Control and Mitigation Technology for Lunar and Martian Exploration

Mars is covered with a layer of dust that has been homogenized by global dust storms. Dust, levitated by these storms as well as by the frequent dust devils, is the dominant weather phenomenon on Mars. NASA's Mars exploration rovers have shown that atmospheric dust falling on solar panels can decrease their efficiency to the point of rendering the rover unusable. Dust covering the surface of the moon is expected to be electrostatically charged due to the solar wind, cosmic rays, and the solar radiation itself through the photoelectric effect. Electrostatically charged dust has a large tendency to adhere to surfaces. The Apollo missions to the moon showed that lunar dust adhesion can hinder manned and unmanned exploration activities. In this paper, we report on our efforts to develop and electrodynamic dust shield to prevent the accumulation of dust on surfaces and to remove dust already adhering to those surfaces. The technology uses electrostatic and dielectrophoretic forces to carry dust particles off surfaces and to generate an electrodynamic shield that prevents further accumulation of dust. The concept of the electrodynamic dust shield was introduced by NASA in the late 1960s and later reduced to practice during the 1970s for terrestrial applications. In 2003, our laboratory, in collaboration with several universities, applied this technology to space applications, specifically to remove dust from solar panels on Mars. We show how, with an appropriate design, we can prevent the electrostatic breakdown at the low Martian atmospheric pressures. We are also able to show that uncharged dust can be lifted and removed from surfaces under simulated Martian environmental conditions. We have also been able to develop a version of the electrodynamic dust shield working under hard vacuum conditions that simulate the lunar environment. We have implemented the electrodynamic dust shield on solar arrays, optical systems, spectrometers, viewports, thermal radiators, batteries, and power systems, as well as on fabrics for spacesuits. We present data on the design and optimization of the electrodynamic dust shields and provide data on the performance of the different implementations of the technology for lunar and Martian exploration activities.

Calle, C. I.↗

DOE OSTI2025

X-ray escape peaks in gamma-ray spectrum acquired by perovskite detector

The X-ray escape peaks are clearly visible in the high-resolution gamma spectra acquired by CsPbBr 3 , credit to the rapidly improving energy resolution of perovskite gamma detectors. But it also raises concerns. If this peak remains as significant as it is, perovskite gamma detectors would have very limited use in complex gamma spectrometry applications. This paper discusses the origin of the escape peaks in CsPbBr 3 detectors, benchmarked against Ge and CZT detectors. The Pb escape peak consists of four escape peaks that are merged together, while the Cs and Br escape peaks are hidden inside the photopeak of 137 Cs (662 keV). These combined effects either create a noticeable gamma peak observed to the left of the 662 keV photopeak when acquired using a high-resolution CsPbBr 3 detector or raise the left slope of the photopeak. We also explore potential methods to mitigate these peaks, such as applying anti-coincidence method. The height of the escape peaks diminishes as the detector volume increases but will not go away entirely. The relationship between the observed Pb escape peak and the detector's dimensions is demonstrated through Monte Carlo simulation.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗

NASA NTRS2010

NASA Self-Assessment of Space Radiation Research

Space exploration involves unavoidable exposures to high-energy galactic cosmic rays whose penetration power and associated secondary radiation makes radiation shielding ineffective and cost prohibitive. NASA recognizing the possible health dangers from cosmic rays notified the U.S. Congress as early as 1959 of the need for a dedicated heavy ion accelerator to study the largely unknown biological effects of galactic cosmic rays on astronauts. Information and scientific tools to study radiation health effects expanded over the new decades as NASA exploration programs to the moon and preparations for Mars exploration were carried out. In the 1970 s through the early 1990 s a more than 3-fold increase over earlier estimates of fatal cancer risks from gamma-rays, and new knowledge of the biological dangers of high LET radiation were obtained. Other research has increased concern for degenerative risks to the central nervous system and other tissues at lower doses compared to earlier estimates. In 1996 a review by the National Academy of Sciences Space Science Board re-iterated the need for a dedicated ground-based accelerator facility capable of providing up to 2000 research hours per year to reduce uncertainties in risks projections and develop effective mitigation measures. In 1998 NASA appropriated funds for construction of a dedicated research facility and the NASA Space Radiation Laboratory (NSRL) opened for research in October of 2003. This year marks the 8th year of NSRL research were about 1000 research hours per year have been utilized. In anticipation of the approaching ten year milestone, funded investigators and selected others are invited to participate in a critical self-assessment of NSRL research progress towards NASA s goals in space radiation research. A Blue and Red Team Assessment format has been integrated into meeting posters and special plenary sessions to allow for a critical debate on the progress of the research and major gaps areas. Blue teams will highlight progress and important new knowledge gained. Red teams will challenge the Blue teams on proposed highlights and point to Gaps not considered. We will review the current space radiation Risks and Gaps under investigation at NASA, critical data sets and research highlights anticipated, and possible goals for future research at NSRL.

Cucinotta, Francis A.↗

NASA NTRSDate not supplied

Cryogenics and Fluids at NASA-Goddard Space Flight Center

Abstract: Spacecraft thermal design presents unique thermal and fluid challenges caused by a variety of harsh spacecraft thermal environments. In addition, at cryogenic temperatures (i.e., less than 123 K (-150° C), and sometimes as low as 50 milliKelvin), more challenges arise, such as the increasing importance of mitigating thermal radiation, the effects of coefficient of thermal expansion mismatches between different materials, changes in the physics behavior of materials, and increasing thermodynamic difficulty of lifting heat up large temperature gradients. In this talk, Dr. Rueger will present a broad overview of spacecraft thermal environments; cryogenic design practices; components of interest for the Cryogenics and Fluids Branch (e.g., cryocoolers, adiabatic demagnetization refrigerators, heat switches, and superconducting leads); cryogenic considerations in some current NASA mission examples (e.g., the DragonFly mission to Titan and the X-ray Imaging and Spectroscopy Mission); and capabilities of the Cryogenics and Fluids Branch at NASA.

Paul Rueger↗

NASA NTRS2019

Bringing Single-Event Effects Down to Earth

In the 47 years since single-event effects were first observed in spacecraft electronics, radiation experts have developed an effective methodology supported by a nationwide infrastructure. A highly skilled workforce of radiation engineers has developed test facilities and methods, modeling and simulation techniques, and mitigation and design strategies to ensure space missions meet their performance and reliability requirements even in the harsh radiation environments of space. Now, increasing performance demands of space missions, the continued disruptive evolution of microcircuit technologies and growth and changes of the space industry have combined with an aging infrastructure are placing increasing strain on the radiation effects community, and the community is responding.

Single-event effects↗

NASA NTRSDate not supplied

Identifying Neutron Irradiation in Space to Mitigate Bio-Medical Effects

One of the primary challenges to interplanetary human travel is mitigation of radiation expo-sure. As fast transit with LENR driven or conventional nuclear electric (NEP) or thermal propulsion (NTP) may be imminent, time and level of radiation exposure composingALARA (As Low as Rea-sonably Achievable) must be ascertained rapidly and precisely. Since acute physiological effects are difficult to detect, and chronic effects on crew health are delayed and potentially trans-generational, improved detection technologies will be game-changing and an essential element of the crew health monitoring and environmental protection toolkit.Secondary Galactic Cosmic Ray (GCR) induced neutrons are an additional hazard.

space medicine↗

NASA NTRS2020

The Galactic Cosmic Ray Simulator at the NASA Space Radiation Research Laboratory

With NASA’s new Artemis plan for a sustainable return to the moon, astronauts will once again leave Earth’s protective magnetosphere only to endure higher levels of radiation from galactic cosmic radiation (GCR). The ever penetrating GCR will continue to pose significant health risks especially as lunar missions increase in duration and as NASA sets its aspirations on Mars. The primary risks of concern include carcinogenesis, central nervous system (CNS) effects resulting in potential in-mission cognitive or behavioral impairment and/or late neurological disorders, and degenerative tissue effects including circulatory and heart disease. Characterization and mitigation of these risks requires a significant reduction in the large biological uncertainties of chronic (low-dose rate) heavy ion exposures and the validation of countermeasures in a relevant space environment. Historically, most research on understanding space radiation-induced health risks has been performed using acute exposures of monoenergetic single-ion beams. However, the space radiation environment consists of a wide variety of ion species over a broad energy range. Using the fast beam switching and controls systems technology recently developed at the NASA Space Radiation Laboratory at Brookhaven National Laboratory, a new era in radiobiological research is possible. NASA has developed the “GCR simulator” to generate a spectrum of ion beams that approximates the primary and secondary GCR field experienced at human organ locations within a deep-space vehicle.

NASA Space Radiation Laboratory↗

NASA NTRSDate not supplied

NASA Space Radiation Laboratory Galactic Cosmic Ray Simulator

With exciting new Agency plans for a sustainable return to the moon, astronauts will once again leave earth’s protective magnetosphere only to endure higher levels of radiation from galactic cosmic rays (GCR) and the possibility of a large solar particle event (SPE). Gateway, lunar landers, and surface habitats will be designed to protect crew against SPEs with vehicle optimization, storm shelter concepts, and/or active dosimetry; however, the ever-penetrating GCR will continue to pose the most significant health risks especially as lunar missions increase in duration and as NASA sets its aspirations on Mars. The primary risks of concern include carcinogenesis, central nervous system effects resulting in potential in-mission cognitive or behavioral impairment and/or late neurological disorders, degenerative tissue effects including cataracts, circulatory and heart disease, as well as, potential immune system decrements impacting multiple aspects of crew health. Characterization and mitigation of these risks requires a significant reduction in the large biological uncertainties of chronic (low-dose rate) heavy ion exposures and the validation of countermeasures in a relevant space environment. NASA has developed the “GCR Simulator” at Brookhaven National Laboratory to generate a spectrum of ion beams that approximates the primary and secondary GCR field experienced at human organ locations within a deep-space vehicle. The majority of the dose is delivered from protons (~65-75%) and helium ions (~10-20%) with heavier ions (Z>3) contributing the remainder. The “GCR Simulator” exposes state-of-the art cellular and animal model systems to 33 sequential beams including 4 proton energies plus degrader, 4 helium energies plus degrader, and the five heavy ions of C, O, Si, Ti, and Fe. A polyethylene degrader is used with the 100 MeV/n H and He beams to provide a nearly continuous distribution of low energy particles. A 500 mGy exposure, delivering doses from each of the 33 beams, requires 75-90 minutes. To more closely simulate the low dose rates found in space, sequential field exposures can be divided into daily fractions over 2-6 weeks, with individual beam fractions as low as 0.1-0.2 mGy. In the large beam configuration (60 x 60 cm2), 54 special housing cages can accommodate 2-3 mice each for a 70-75 min duration or ~15 individually housed rats. Emerging research results from our 2018 runs utilizing mixed heavy ion fields and protracted space exposures are forthcoming and will deepen our understanding of the numerous health risks faced by astronauts. This talk discusses NASA’s innovative technology solution for a ground-based GCR simulator at the NASA Space Radiation Laboratory to enable future exploration missions.

galactic cosmic ray simulator↗

DOE OSTI2024

Response of 11 B enriched ZrB 2 ultra-high temperature ceramic to neutron irradiation at elevated temperatures

ZrB 2 , an ultra-high temperature ceramic (UHTC) is being considered for use in fusion reactor first-wall structures, yet its response to irradiation remains poorly understood. This study employed scanning/transmission electron microscopy (S/TEM), synchrotron X-ray diffraction (XRD), finite element calculations, and thermal property measurements to thoroughly investigate the neutron-irradiation effects on 11 B-enriched ZrB 2 . Neutron irradiations were conducted at 220 °C and 620 °C, with a neutron fluence of 2.2 × 10 25 neutron/m 2 (energy > 0.1 MeV), resulting in 3.9 dpa and 4200 appm He. The study revealed the unusual prevalence of prism loops and a > c anisotropic lattice swelling, likely linked to the low c/a ratio of ZrB 2 , leading to grain boundary microcracking. Reducing the grain sizes was effective in reducing intergranular cracking and macroscopic swelling. The observation of cavities in ZrB 2 irradiated at 620 °C, as opposed to 220 °C, prompts questions about the temperature at which vacancies in ZrB 2 become mobile, and the role of neutron absorption by 10 B in elevating irradiation temperatures. Isotopic enrichment in 11 B proves to be a viable strategy for mitigating helium production in transition-metal diborides, which is a critical consideration for nuclear applications. Irradiation-induced defects reduce the thermal diffusivity and conductivity of ZrB 2 by a factor of 4–9, which has important implications for its role as a plasma-facing material in fusion reactors that drive high heat fluxes through first-wall materials. Here, this comprehensive study lays the foundation for understanding ZrB 2 behavior under neutron irradiation and highlights important phenomena to consider for various material applications.

36 MATERIALS SCIENCE↗

NASA NTRS2021

EXEP: Catching the rays- modeling the stray light background of a starshade.

Diffraction and reflection from the optical edges is the dominant source of stray light from a starshade. However, recent progress in optical edge design has led to much reduced predictions of stray light deriving from this source. Secondary sources now also play a role; these sources arise from two or more reflections from the starshade structure. These multiple reflections allow light to reach the telescope from parts of the structure that are shaded from direct sunlight. Here we analyze the secondary sources for the starshade model developed as part of the NASA’s S5 starshade technology development and show the effects of optical edge mechanical design variants and mitigations.

Stegman, Matthew↗

NASA NTRS2014

Space Radiation and Risks to Human Health

The radiation environment in space poses significant challenges to human health and is a major concern for long duration manned space missions. Outside the Earth's protective magnetosphere, astronauts are exposed to higher levels of galactic cosmic rays, whose physical characteristics are distinct from terrestrial sources of radiation such as x‐rays and gamma‐rays. Galactic cosmic rays consist of high energy and high mass nuclei as well as high energy protons; they impart unique biological damage as they traverse through tissue with impacts on human health that are largely unknown. The major health issues of concern are the risks of radiation carcinogenesis, acute and late decrements to the central nervous system, degenerative tissue effects such as cardiovascular disease, as well as possible acute radiation syndromes due to an unshielded exposure to a large solar particle event. The NASA Human Research Program's Space Radiation Program Element is focused on characterization and mitigation of these space radiation health risks along with understanding these risks in context of the other biological stressors found in the space environment. In this overview, we will provide a description of these health risks and the Element's research strategies to understand and mitigate these risks.

Huff, Janice L.↗

NASA NTRS2014

Space Radiation and Risks to Human Health

Huff, Janice L.↗

DOE OSTI2026

A Cryogenic Muon Tagging System Integrated with a Superconducting Qubit Device for Radiation-Induced Error Mitigation

Superconducting qubits are highly sensitive to ionizing radiation, which can induce correlated errors and limit scalable fault-tolerant quantum computing. In particular, cosmic-ray muons can deposit energy in the substrate, generating phonon bursts that break Cooper pairs and produce quasiparticles, leading to correlated decoherence events across multiple qubits. We present the development of a cryogenic muon tagging system based on Kinetic Inductance Detectors (KIDs) and its integration with superconducting quantum hardware. Originally developed within the ACE-SuperQ project and validated as a standalone detector, the system demonstrated a muon tagging efficiency of approximately 90% and excellent agreement with Monte Carlo simulations. Building on this validation, the tagging system has been integrated with a multi-qubit superconducting chip operated in a dilution refrigerator. The detector configuration consists of a multi-layer KID stack arranged above and below the quantum device, enabling time-coincident identification of muon-induced events within the same cryogenic environment. The integrated setup has been successfully commissioned, enabling simultaneous operation of the qubit chip and the muon tagging system. A first measurement campaign has been carried out, and preliminary data show time-correlated events between the muon tagging detectors and the qubit readout. A quantitative analysis of radiation-induced effects on qubit performance is currently ongoing. This work represents a step toward the implementation of event-level radiation tagging as a tool for characterizing and potentially mitigating correlated errors in superconducting quantum processors, while establishing a modular platform for future studies at the interface between particle physics and quantum information science.

Roy, Tanay [Fermilab] (ORCID:000000019442862X)↗

NASA NTRS2020

Progress of Coating Stress Compensation of Silicon Mirrors for Lynx X-ray Telescope Mission Concept Using Thermal Oxide Patterning Method

A thermal oxide patterning method has proven to be effective for correcting coating-stress-induced distortion on flat silicon wafers. We report progress on developing this method for correcting curved silicon mirrors distorted by front-side iridium coatings. Owing to the difference in geometry, a finite element model has been established to calculate the appropriate duty cycle maps in thermal oxide hexagon patterns used for compensation. In addition, a photolithographic process, along with three-dimensional printed equipment, has been developed for creating patterns precisely on the back side of curved mirrors. The developed method has been used to recover the original surface shape of two silicon mirrors which are 100-mm long, 0.5-mm thick, having 312-mm radius of curvature, and 30 deg in azimuthal span (Wolter-I geometry). These mirrors’ front sides are sputter-coated by 20-nm iridium layers with ∼-70 N∕m integrated stress. Measurement results show that the developed method can mitigate coating-induced distortion by a factor of ∼5 in RMS height and ∼4 in RMS slope error, corresponding to ∼0.5 arc sec RMS slope error. Residual errors after correction are dominated by midfrequency ripples created during the annealing process, which will be resolved in the future. The presented method is precise and inexpensive and a potential candidate for resolving the coating stress issue for Lynx optics in the future.

x-ray↗

NASA NTRS2005

Managing Lunar and Mars Mission Radiation Risks: Cancer Risks, Uncertainties, and Shielding Effectiveness - Part 1

This document addresses calculations of probability distribution functions (PDFs) representing uncertainties in projecting fatal cancer risk from galactic cosmic rays (GCR) and solar particle events (SPEs). PDFs are used to test the effectiveness of potential radiation shielding approaches. Monte-Carlo techniques are used to propagate uncertainties in risk coefficients determined from epidemiology data, dose and dose-rate reduction factors, quality factors, and physics models of radiation environments. Competing mortality risks and functional correlations in radiation quality factor uncertainties are treated in the calculations. The cancer risk uncertainty is about four-fold for lunar and Mars mission risk projections. For short-stay lunar missins (<180 d), SPEs present the most significant risk, but one effectively mitigated by shielding. For long-duration (>180 d) lunar or Mars missions, GCR risks may exceed radiation risk limits. While shielding materials are marginally effective in reducing GCR cancer risks because of the penetrating nature of GCR and secondary radiation produced in tissue by relativisitc particles, polyethylene or carbon composite shielding cannot be shown to significantly reduce risk compared to aluminum shielding. Therefore, improving our knowledge of space radiobiology to narrow uncertainties that lead to wide PDFs is the best approach to ensure radiation protection goals are met for space exploration.

Cucinotta, Francis A.↗