Prolonged Space Missions Research Articles

Improvement and optimization of spacecraft environmental control and life support systems

Environmental control and life support systems (ECLSS) are essential for the triumph of human spaceflight missions, furnishing astronauts with crucial resources like breathable air, purified water, nourishment, and protection from radiation. The unique and challenging space environment, coupled with the critical nature of ECLSS components, necessitates a high degree of reliability to prevent catastrophic failures. This paper conducts a comprehensive examination of various ECLSS subsystems, including air revitalization, water processing, food storage, waste management, and radiation shielding. Gaining perspectives from historical missions like Apollo, Skylab, and the International Space Station (ISS), the research outlines strategic approaches to improve the fault tolerance of ECLSS. The implementation of advanced simulation modeling, strategic component redundancy, and improved subsystem interconnectivity are posited as pivotal measures to bolster the reliability of ECLSS. These improvements are vital to guarantee the safety and viability of prolonged space missions to the Moon, Mars, and beyond, thereby facilitating humanitys ongoing exploration of the universe.

Navigating the Challenges of 3D Printing Personalized Medicine in Space Explorations: A Comprehensive Review.

Space exploration has undergone a paradigm shift in recent years, with a growing emphasis on long-duration missions and human habitation on other celestial bodies. Private aerospace businesses are at the forefront of advancing the next iteration of spacecraft, encompassing a wide range of applications such as deep space exploration (e.g., SpaceX) and cost-effective satellite deployments (e.g., Rocketlab). One of the critical challenges associated with prolonged space missions is the provision of personalized medical care. 3D printing technology has emerged as a potential solution, enabling the on-demand production of personalized medical devices and medications. However, the unique conditions of space pose substantial challenges to the successful implementation of 3D printing for personalized medicine. Tremendous scope for research exists in terms of resource utilization and waste management in space ecosystem, robotic and artificial intelligence (AI) enabled tool utilization, remote operability, interplanetary travel, space education and training tools, digital twins, space tourism and in many other aspects of 3D printing for personalized medicine in space explorations.

Lifetime evaluation of left ventricular structure and function in male ApoE null mice after gamma and space-type radiation exposure.

The space radiation (IR) environment contains high charge and energy (HZE) nuclei emitted from galactic cosmic rays with the ability to overcome current shielding strategies, posing increased IR-induced cardiovascular disease risks for astronauts on prolonged space missions. Little is known about the effect of 5-ion simplified galactic cosmic ray simulation (simGCRsim) exposure on left ventricular (LV) function. Three-month-old, age-matched male Apolipoprotein E (ApoE) null mice were irradiated with 137Cs gamma (γ; 100, 200, and 400cGy) and simGCRsim (50, 100, 150cGy all at 500 MeV/nucleon (n)). LV function was assessed using transthoracic echocardiography at early/acute (14 and 28days) and late/degenerative (365, 440, and 660days) times post-irradiation. As early as 14 and 28-days post IR, LV systolic function was reduced in both IR groups across all doses. At 14days post-IR, 150cGy simGCRsim-IR mice had decreased diastolic wall strain (DWS), suggesting increased myocardial stiffness. This was also observed later in 100cGy γ-IR mice at 28days. At later stages, a significant decrease in LV systolic function was observed in the 400cGy γ-IR mice. Otherwise, there was no difference in the LV systolic function or structure at the remaining time points across the IR groups. We evaluated the expression of genes involved in hemodynamic stress, cardiac remodeling, inflammation, and calcium handling in LVs harvested 28days post-IR. At 28days post-IR, there is increased expression of Bnp and Ncx in both IR groups at the lowest doses, suggesting impaired function contributes to hemodynamic stress and altered calcium handling. The expression of Gals3 and β-Mhc were increased in simGCRsim and γ-IR mice respectively, suggesting there may be IR-specific cardiac remodeling. IR groups were modeled to calculate the Relative Biological Effectiveness (RBE) and Radiation Effects Ratio (RER). No lower threshold was determined using the observed dose-response curves. These findings do not exclude the possibility of the existence of a lower IR threshold or the presence of IR-induced cardiovascular disease (CVD) when combined with additional space travel stressors, e.g., microgravity.

Anorthosite (Lunar Rock Replicant) - An Anti-Cancerous Medicinal Approach for H460: Human Lung Cancer with Validation via ROS Anti-Oxidant Analysis

Anorthosite, a commonly occurring mineral found in lunar regolith, holds the promise of a groundbreaking dual application in the fields of cancer therapy and space medicine. In the context of lung cancer therapy, anorthosite nanoparticles were synthesized and subjected to MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) assay along with FTIR to assess their cytotoxic effects on H460 lung cancer cells. The results revealed that anorthosite nanoparticles exhibit a dose-dependent cytotoxic effect on H460 cells, suggesting their potential as a novel treatment modality for lung cancer with Inhibitory Concentration IC50 value at 50% to be 21.65 which simply gestures of how toxic it could be if being treated as a cancer drug via chemo/immune/radio or target cell therapies, even when merged with ayurvedic discipline. These findings warrant further investigations into the precise mechanisms of anorthosite-mediated cytotoxicity and its therapeutic potential in vivo. Moreover, anorthosite's role in space medicine was explored by assessing its ability to mitigate oxidative stress, a major concern for astronauts exposed to the harsh space environment. Reactive oxygen species (ROS) generated during space travel can have detrimental effects on an astronaut's health. Anorthosite nanoparticles were tested for their capacity to scavenge ROS in an in vitro model. The results demonstrated that anorthosite nanoparticles possess potent antioxidant properties, indicating their potential in safeguarding astronauts from oxidative stress-induced health issues during prolonged space missions. This dual-application research on anorthosite nanoparticles highlights their therapeutic potential for lung cancer treatment and their utility in protecting astronauts from oxidative stress in space.

Immunological, hormonal and hemostasis parameters in cosmonauts’ blood after long-term orbital missions

The extreme factors associated with space flight influence pronouncedly various physiological systems of the human body. The current study focuses on the impact of factors associated with prolonged space missions lasting up to 6 months on cellular innate immunity, hormonalregulation, and hemostasis in Russian cosmonauts. Immune system adaptation to the conditions of long-term space flight was shown to be accompanied by a significant increase in the level of monocytes and granulocytes, along with a decreased number of cells expressing adhesion molecules. The coagulation cascade, main anticoagulant and fibrinolysis proteins were also evaluated. The early post-flight period was characterized by elevated D-dimer levels compared to baseline values, indicative of blood clotting and fibrinolysis activation caused by a damage of endothelium during landing. aAlterations in blood rheology during re-adaptation to Earth conditions was also observed. The blood concentrations of aldosterone, cortisol, estradiol, testosterone, osteocalcin, and erythropoietin were analyzed, and their correlation with the parameters of hemostasis was assessed.The summary findings indicate an adaptive physiological reaction in cosmonauts associated with 6 months duration of spaceflight. The observations may be related to endothelium damage, which manifested in the activation of certain components of the immune system, along with the activation of fibrin clot formation and subsequent fibrinolysis.

Novel concept of tailorable magnetic field and electron pressure distribution in a magnetic nozzle for effective space propulsion

Magnetic nozzle appears to be a practical solution for prolonged space missions. For efficient handling of the spaceship, an in-flight solution to customize the thrust from the magnetic nozzle is essential. Here a new concept of three-thick coils system is proposed for tailoring the magnetic field in-flight in accordance with electron pressure distribution. The role of peak position of the pressure and its axial gradient is also uncovered for realizing higher thrust. About three-fold increase in thrust is observed when the electron temperature is raised to ∼2.5 times of its original value at the exit plane. The set-up is optimized for its best performance and efficient use in the electric space propulsion sector with thrust approaching 5 mN. In particular, this can contribute to the attitude control or the precision pointing of the spacecraft, the technology for removal of space debris and manipulating the ion momentum flux lost to a wall or unsteady laser produced plasma flow in a magnetic nozzle.

Medical Support of Manned Long-Duration Missions (One Year or Longer) on the Mir Orbital Space Station

We analyzed the results of medical control (MC) and medical situations and assessed the efficacy of measures to manage the medical cases recorded by Russian cosmonauts (aged 36 to 52 years) engaged in their long-duration (about one year or more) space missions (SM) on the Mir orbital station (OS). The standard monitoring of the crewmembers’ health during their stay on the Mir OS was performed within the program of MC, which was subdivided into operative and routine checkups, as well as included periodic extensive medical investigations. According to ECGs from 12 leads during the SM, changes in cardiac rhythm in terms of single and rare extrasystoles were observed in two cosmonauts, and the recorded decreases in the amplitude of T peaks varied in the majority of ECG leads from 23 to 70% in four out of five cosmonauts. The indicated changes were not qualified as pathological and did not require any pharmacological correction. The functional test results obtained in the periodic extensive medical investigations have shown no significant deviations and were consistent with the general patterns of human body responses to these tests under other SM conditions. The analysis of infrequent medical situations recorded in long-duration missions has shown the absence of any specific differences associated with the factor of more prolonged SMs. All somatic and functional disorders have been successfully managed using the onboard kits for medical aid. Russian system of space mission care has provided minimization of medical risks and permitted the preservation of cosmonauts’ health and workability in long duration missions (for nearly one year and more).

Visual disturbances during prolonged space missions.

During prolonged spaceflight, astronauts often experience ocular changes, due to constant head-ward fluid shifts in space as compared with Earth. This article reviews symptoms, likely causes, and potential solutions, such as lower body negative pressure, to counteract space-associated neuroocular syndrome (SANS). Low gravity conditions and other aspects of spaceflight affect the eye detrimentally, causing SANS which is characterized by optic disc edema, choroidal thickening, cotton wool spots, and a hyperopic shift. SANS is probably caused by altered hemodynamic flows in the head and neck as well as mildly elevated intracranial and intraocular pressures. Carbon dioxide and other chemicals in space-craft may influence SANS as well. SANS may be counteracted by using lower body negative pressure, thigh cuffs, spacecraft engineering, and/or artificial gravity by a centrifuge. Prolonged space missions are associated with optic disc edema, choroidal thickening, cotton wool spots, and a hyperopic shift. Possible causes and countermeasures are currently being researched to reduce the risk of SANS. Although many countermeasures to SANS are under investigation lower body negative pressure exhibits great promise in counteracting the headward fluid shifts in space. Understanding and prevention of SANS is critical to future space exploration, especially to long-duration missions to the moon and Mars.

A novel numerical model for the prediction of patient-dependent bone density loss in microgravity based on micro-CT images

The deterioration of the musculoskeletal system is a serious health concern for long-term space missions. The accumulated information over the past decades of space flights showed that microgravity impacts significantly the musculoskeletal system with muscle atrophy and bone loss. Until now, it has been difficult to make reasonable predictions of the bone loss for prolonged space missions due to the lack of in-space experimental data and weak understanding of the mechanobiological bone mechanisms. On earth, the healthy musculoskeletal degradation is mainly age related with osteoporosis and delayed fracture healing. A better understanding of the bone mechanobiological functions could help us improve our model predictions of the musculoskeletal health system during long-term space missions. We develop a numerical model able to predict the bone loss at the mesoscopic scale (bone trabecula) in microgravity. The model is able to correlate the calculated bone degradation mechanism with data available in the literature showing the effective bone density loss measured experimentally. An optimization algorithm is used for an average bone microstructure distribution and long-term prediction. Extrapolation is made to link the local bone loss at the structural scale with the corresponding effective bone strength. The first part of the paper details the extraction of the bone microstructure using micro-CT images and numerical model development. Next, the degradation and optimization schemes are detailed. Finally, some results are presented for long-term degradation.

Neurophysiological changes in simulated microgravity: An animal model.

Microgravity (MG) is one of the main problems that astronauts have to cope with during space missions. Long-duration space travel can have detrimental effects on human neurophysiology. Despite scientific efforts, these effects are still insufficiently investigated. Animal earth-based analogs are used to investigate potential nervous system associated perturbations that might occur during prolonged space missions. Hindlimb unloading, Tail suspension and Pelvic suspension models are currently used in MG studies. Loss of homeostasis of certain biological pathways in the nervous system can lead to the functioning and expression of receptors/genes, and the release and functioning of neurotransmitters and neuronal membrane ion channels into specific brain regions. The potential impact of MG on molecular mechanisms linked to neurophysiology through animal earth-based analogs is reviewed. The effect of molecular signalling pathways on the decline of neuronal connectivity and cognitive and neuroplasticity function under MG simulated conditions will be studied. The role of biomarkers including neurotransmitters, genes or receptors will be highlighted in the healthy and MG-affected brain. MG-mediated neurodegenerative mechanisms linked to learning and memory impairment will be highlighted. This review depicts the current rodent models applied to simulate MG ground based approaches and investigates the MG induced changes in the nervous system. The neuropathological profile of the above animal MG ground-based models can be comparable to the effects of ageing, anxiety and other neurological disorders. The advantages and limitations of the existing approaches are discussed. MG induced neurophysiology outcomes can be extrapolated to study other clinical applications.

Abstract 4158: Differential intestinal tumorigenesis and DNA repair response in APCMin/+ mice after acute and fractionated proton radiation

Abstract Ionizing radiation (IR) exposure is a risk factor for colorectal cancer (CRC) development. With increasing interest in exploring outer space, astronauts on prolonged space missions such as a mission to Mars are expected to receive IR doses that could heighten the risk of CRC. It is estimated that about 90% of the IR in outer space is energetic protons, and the radiation dose during solar particle events (SPEs) could reach up to 2 Gy behind shielding. However, the risk of CRC after energetic proton radiation is not yet fully defined due to lack of human or animal model data. The purpose of the current study was to quantitatively and qualitatively compare and characterize differences in intestinal tumorigenesis between acute and fractionated proton irradiation in APCMin/+ mice, a well-established mouse model for human CRC. Mice were exposed to 1.88 Gy of proton radiation delivered in a single fraction or in 4 equal daily fractions (0.47 Gy x 4). Since proton dose to astronauts are variable based on space environment, in this initial study we chose a high single dose and a lower daily dose pattern to assess intestinal tumorigenesis. Intestinal tumor frequency and grade were noted, and tumor samples were collected from irradiated and control mice euthanized 100 to 110 days after radiation exposure. Molecular analysis was focused on DNA damage and repair, and cellular proliferative signaling pathways relevant to CRC using immunoblots, immunohistochemistry, and qPCR. Relative to control and fractionated-protons, there was significantly higher intestinal tumor frequency and grade after acute (single dose) proton irradiation. Decreased cellular differentiation and increased oxidative damage to DNA was observed after acute proton radiation. At the molecular level, our data showed increased DNA double strand breaks associated with decreased levels of DNA repair proteins, and upregulation of proliferative β-catenin and Akt signaling after acute proton exposure. Since increased DNA damage was not associated with concomitant increased apoptosis, our data suggest continued proliferation of cells bearing sub-lethal damage to promote tumorigenesis. In the fractionated proton group, tumor frequency and grade as well as molecular changes were comparable to sham-irradiated control group. When considered along with decreased tumor frequency and upregulation of DNA repair pathways after fractionation, our data are suggestive of marked differences in carcinogenic effects of acute vs. fractionated proton radiation. In summary, our data suggest that acute exposure to proton radiation is associated with higher risk of intestinal tumorigenesis in APCMin/+ mice with implications for gastrointestinal cancer risk in astronauts undertaking long duration space missions and in patients undergoing proton radiotherapy. Citation Format: Kamal Datta, Shubhankar Suman, Santosh Kumar, Albert J. Fornace. Differential intestinal tumorigenesis and DNA repair response in APCMin/+ mice after acute and fractionated proton radiation [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 4158.

Evaluation of psychological stress in confined environments using salivary, skin, and facial image parameters

Detecting the influence of psychological stress is particularly important in prolonged space missions. In this study, we determined potential markers of psychological stress in a confined environment. We examined 23 Japanese subjects staying for 2 weeks in a confined facility at Tsukuba Space Center, measuring salivary, skin, and facial image parameters. Saliva was collected at four points in a single day to detect diurnal variation. Increases in salivary cortisol were detected after waking up on the 4th and 11th days, and at 15:30 on the 1st and in the second half of the stay. Transepidermal water loss (TEWL) and sebum content of the skin were higher compared with outside the facility on the 4th and 1st days respectively. Increased IL-1β in the stripped stratum corneum was observed on the 14th day, and 7 days after leaving. Differences in facial expression symmetry at the time of facial expression changes were observed on 11th and 14th days. Thus, we detected a transition of psychological stress using salivary cortisol profiles and skin physiological parameters. The results also suggested that IL-1β in the stripped stratum corneum and facial expression symmetry are possible novel markers for conveniently detecting psychological stress.

Long-term evaluation of orbital dynamics in the Sun-planet system considering axial-tilt

In this paper, the axial-tilt (obliquity) effect of planets on the motion of planets’ orbiter in prolonged space missions has been investigated in the presence of the Sun gravity. The proposed model is based on non-simplified perturbed dynamic equations of planetary orbiter motion. From a new point of view, in this work, the dynamic equations regarding a disturbing body in elliptic inclined three-dimensional orbit are derived. The accuracy of this non-simplified method is validated with dual-averaged method employed on a generalized Earth–Moon system. It is shown that the neglected short-time oscillations in dual-averaged technique can accumulate and propel to remarkable errors in the prolonged evolution. After validation, the effects of the planet’s axial-tilt on eccentricity, inclination and right ascension of the ascending node of the orbiter are investigated. Moreover, a generalized model is provided to study the effects of third-body inclination and eccentricity on orbit characteristics. It is shown that the planet’s axial-tilt is the key to facilitating some significant changes in orbital elements in long-term mission and short-time oscillations must be considered in accurate prolonged evaluation.

Abstract A25: Intestinal tumorigenesis in APCMin/+ mice was higher after acute relative to fractionated proton radiation: Implications for space radiation-induced colorectal carcinogenesis

Abstract Ionizing radiation (IR) is a risk factor for colorectal cancer (CRC) based on epidemiologic studies. With increasing interest in exploring outer space, astronauts on prolonged space missions such as a mission to Mars will be exposed to IR doses that are expected to heighten the risk of CRC. Sources of space radiation beyond Earth's magnetosphere are galactic cosmic radiation (GCR) and solar particle event (SPE) and about 90% of the IR in outer space is energetic protons, which are more damaging than photon radiations such as γ-rays. While astronauts on deep-space missions are estimated to receive ~250 μGy/day of proton, radiation dose during SPE could reach up to ~2 Gy behind shielding. However, the risk of CRC after energetic proton radiation is not yet fully defined due to lack of human or animal model data. Limitations in obtaining adequate human data mandate that in vivo mechanistic data for CRC risk estimates be obtained using animal models and surrogate biologic and molecular end points relevant to human disease process. The purpose of the current study was to quantitatively and qualitatively compare and characterize differences in intestinal tumorigenesis between acute and fractionated proton irradiation in APCMin/+ mice, a well-established mouse model for human CRC. Mice were exposed to 1.88 Gy of proton radiation delivered in a single fraction or in 4 equal daily fractions (0.47 Gy x 4). Since proton dose to astronauts is variable based on space environment, in this initial study we chose a high single dose and a low daily dose pattern to assess intestinal tumorigenesis. Intestinal tumor frequency and grade were noted, and tumor and normal tissue samples were collected from irradiated and control mice euthanized 100 to 110 days after radiation exposure. Molecular analysis was focused on DNA damage, genomic instability, specific epigenetic changes and mutation analysis, and cellular proliferative signaling pathways relevant to CRC using immunoblots, immunohistochemistry, and PCR. Relative to control and fractionated protons, there was significantly higher intestinal tumor frequency and grade after acute proton irradiation. At the molecular level our data showed increased DNA damage and DNA double-strand breaks, decreased genomic stability, and upregulation of proliferative β-catenin and Akt signaling after acute proton exposure. Since increased DNA damage was not associated with concomitant increased apoptosis and there was increased microsatellite instability, our data are suggestive of continued proliferation of cells bearing sublethal damages. Mutational analysis showed significantly more tumors had higher overall mutation frequency and increased p53 hot spot mutations after acute relative to fractionated proton exposure. In fractionated proton groups, tumor frequency and grade as well as molecular changes were statistically comparable to control groups. When considered along with higher mutational frequency and altered promoter methylation of key CRC-related genes in tumor adjacent normal tissues, our data are suggestive of marked differences in carcinogenesis of acute vs. fractionated proton radiation with higher tumorigenic effects associated with acute exposures. Citation Format: Shubhankar Suman, Bo-Hyun Moon, Albert J. Fornace, Jr., Kamal Datta. Intestinal tumorigenesis in APCMin/+ mice was higher after acute relative to fractionated proton radiation: Implications for space radiation-induced colorectal carcinogenesis [abstract]. In: Proceedings of the AACR Special Conference: Advances in Modeling Cancer in Mice: Technology, Biology, and Beyond; 2017 Sep 24-27; Orlando, Florida. Philadelphia (PA): AACR; Cancer Res 2018;78(10 Suppl):Abstract nr A25.

Exposure of the Bone Marrow Microenvironment to Simulated Solar and Galactic Cosmic Radiation Induces Biological Bystander Effects on Human Hematopoiesis

The stem cell compartment of the hematopoietic system constitutes one of the most radiosensitive tissues of the body and leukemias represent one of the most frequent radiogenic cancers with short latency periods. As such, leukemias may pose a particular threat to astronauts during prolonged space missions. Control of hematopoiesis is tightly governed by a specialized bone marrow (BM) microenvironment/niche. As such, any environmental insult that damages cells of this niche would be expected to produce pronounced effects on the types and functionality of hematopoietic/immune cells generated. We recently reported that direct exposure of human hematopoietic stem cells (HSC) to simulated solar energetic particle (SEP) and galactic cosmic ray (GCR) radiation dramatically altered the differentiative potential of these cells, and that simulated GCR exposures can directly induce DNA damage and mutations within human HSC, which led to leukemic transformation when these cells repopulated murine recipients. In this study, we performed the first in-depth examination to define changes that occur in mesenchymal stem cells present in the human BM niche following exposure to accelerated protons and iron ions and assess the impact these changes have upon human hematopoiesis. Our data provide compelling evidence that simulated SEP/GCR exposures can also contribute to defective hematopoiesis/immunity through so-called "biological bystander effects" by damaging the stromal cells that comprise the human marrow microenvironment, thereby altering their ability to support normal hematopoiesis.

2-D clinorotation alters the uptake of some nutrients in Arabidopsis thaliana

Future long-term spaceflight missions rely on bioregenerative life support systems (BLSS) in order to provide the required resources for crew survival. Higher plants provide an essential part since they supply food and oxygen and recycle carbon dioxide. There are indications that under space conditions plants might be inefficient regarding the uptake, transport and distribution of nutrients, which in turn affects growth and metabolism. Therefore, Arabidopsis thaliana (Col-0) seeds were germinated and grown for five days under fast clinorotation (2-D clinostat, 60rpm) in order to simulate microgravity. Concentrations of ten different nutrients (potassium, sulfur, phosphorus, calcium, sodium, magnesium, manganese, iron, zinc, and boron) in shoots of plants grown under reduced and normal (1g) gravity conditions were compared. A protocol was developed for the determination of different nutrients by means of inductively coupled plasma optical emission spectrometry (ICPOES), flame emission spectrometry and spectrophotometry. The concentrations of boron and sulfur were significantly decreased in clinorotated shoots, while the concentration of sodium was elevated, suggesting that altered gravity conditions differentially affected nutrient uptake. Possible mechanisms for such effects include reduced transpiration, altered expression of channels or transporters and direct effects on nutrient assimilation. The observed nutrient imbalances might have a negative impact on plant growth and nutritional quality during prolonged space missions.

Spatial Memory Performance of Socially Mature Wistar Rats is Impaired after Exposure to Low (5 cGy) Doses of 1 GeV/n 48Ti Particles.

Prolonged deep space missions to planets and asteroids will expose astronauts to galactic cosmic radiation (GCR), a mixture of low-LET ionizing radiations, high-energy protons and high-Z and energy (HZE) particles. Ground-based experiments are used to determine whether this radiation environment will have an effect on the long-term health of astronauts and their ability to complete various tasks during their mission. Emerging data suggest that mission-relevant HZE doses impair several hippocampus-dependent neurocognitive processes in rodents, but that there is substantial interindividual variation in the severity of neurocognitive impairment, ranging from no observable effects to severe impairment. While the majority of studies have established the effect that the most abundant HZE species (56Fe) has on neurocognition, some studies suggest that the lighter 48Ti HZE particles may be equally, if not more, potent at impairing neurocognition. In this study, we assessed the effect that exposure to 5-20 cGy 1 GeV/n 48Ti had on the spatial memory performance of socially mature male Wistar rats. Acute exposures to mission-relevant doses (≤5 cGy) of 1 GeV/n 48Ti significantly (P < 0.05) reduced the mean spatial memory performance of the rats at three months after exposure, and significantly (P < 0.015) increased the percentage of rats that have severe (Z score ≥ 2) impairment, i.e., poor performers. Collectively, these data further support the notion that the LET dependency of neurocognitive impairment may differ from that of cell killing.

Radiation‐Hard and Ultralightweight Polycrystalline Cadmium Telluride Thin‐Film Solar Cells for Space Applications

AbstractAchieving high‐specific‐power and radiation hardness of solar cells is of great importance to perform tasks and achieve duration in space. Therefore, we investigated the proton irradiation resistance of ultralightweight CdS/CdTe thin film solar cells having high specific power values. High‐energy proton beams (15 MeV) with doses ranging from 1×1012 to 1×1015 cm−2 were used, equivalent to more than 2000 years in low Earth orbit. Although 70 % decrease in cell conversion efficiency was observed after proton irradiation with dose of 1×1015 cm−2, it still maintained the photovoltaic performance. The specific power of the fabricated cell decreased from 358 W kg−1 to 109 W kg−1 after proton irradiation (dose=1×1015 cm−2), which is still comparable to specific powers of other types of solar cells. Our work indicated that reduction of short circuit current is a major factor of deterioration of the cell performance under the high energy proton irradiation. This work revealed that our lightweight CdS/CdTe solar cells have significant potential for the use in space applications: reduction of launch cost by achieving high specific power and assurance of durability over prolonged space missions.

Impaired Spatial Memory Performance in Adult Wistar Rats Exposed to Low (5-20 cGy) Doses of 1 GeV/n (56)Fe Particles.

Prolonged deep space missions to planets and asteroids will expose astronauts to galactic cosmic radiation, comprised of low-linear energy transfer (LET) ionizing radiations, high-energy protons and high-Z and energy (HZE) particles, such as (56)Fe nuclei. In prior studies with rodents exposed to HZE particle radiation at doses likely to be encountered during deep space missions (<20 cGy) investigators reported impaired hippocampal-dependent neurocognitive performance and further observed substantial variation among the irradiated animals in neurocognitive impairment, ranging from no observable effects to severe impairment. These findings point to the importance of incorporating quantitative measures of interindividual variations into next generation risk assessment models of radiation risks on neurocognition. In this study, 269 male proven breeder Wistar rats were exposed to 1 GeV/n (56)Fe at doses of 0, 5, 10, 15 and 20 cGy, and tested for spatial memory performance on the Barnes maze at three months after exposure. The radiation response data were compared using changes in mean cohort performance and by the proportion of poor responders using the performance benchmark of two standard deviations below the mean value among the sham-irradiated cohort. Acute exposures to mission-relevant doses of 1 GeV/n (56)Fe reduced the mean spatial memory performance at three months after exposure (P < 0.002) and increased the proportions of poor performers, 2- to 3-fold. However, a substantial fraction of animals in all exposure cohorts showed no detectable change in performance, compared to the distribution of sham-irradiated animals. Our findings suggest that individualized metrics of susceptibility or resistance to radiation-induce changes in neurocognitive performance will be advantageous to the development of probabilistic risk assessment models for HZE-induced neurocognitive impairment.

The biological effects induced by high-charged and energy particles and its application in cancer therapy

The radiobiological effects of high atomic number and energy (HZE par cles) ion beams are of interest for radioprotec on in space and tumor radiotherapy. Space radia on mainly consists of heavy charged par cles from protons to iron ions, which is dis nct from common terrestrial forms of radia on. HZE par cles pose a significant cancer risk to astronauts on prolonged space missions. With high delivered energies and intense ioniza on, HZE par cles can damage not only the biological systems but also the shielding materials. HZE par cles are more effec ve than low-LET radia on like γor X-rays to induce gene c muta on and cancer. On Earth, similar ions are being used for targeted cancer therapy due to the advantage of the inverse dose profile, with delivering higher doses to the tumor while keeping lower doses to the surrounding ssues. In this review, we focus on the recent insights into the biological effects caused by HZE par cles and the corresponding mechanism. We also discuss the current applica on of HZE par cle in cancer therapy. Understanding the mechanisms underlying the repair of DNA damage induced by HZE par cles contribute to accurately es mate the risks to human health associated with HZE par cle exposure and to improve the effec veness of tumor radiotherapy.