Long-duration Spaceflight Research Articles

Microgravity and Human Body: Unraveling the Potential Role of Heat-Shock Proteins in Spaceflight and Future Space Missions

In recent years, the increasing number of long-duration space missions has prompted the scientific community to undertake a more comprehensive examination of the impact of microgravity on the human body during spaceflight. This review aims to assess the current knowledge regarding the consequences of exposure to an extreme environment, like microgravity, on the human body, focusing on the role of heat-shock proteins (HSPs). Previous studies have demonstrated that long-term exposure to microgravity during spaceflight can cause various changes in the human body, such as muscle atrophy, changes in muscle fiber composition, cardiovascular function, bone density, and even immune system functions. It has been postulated that heat-shock proteins (HSPs) may play a role in mitigating the harmful effects of microgravity-induced stress. According to past studies, heat-shock proteins (HSPs) are upregulated under simulated microgravity conditions. This upregulation assists in the maintenance of the proper folding and function of other proteins during stressful conditions, thereby safeguarding the physiological systems of organisms from the detrimental effects of microgravity. HSPs could also be used as biomarkers to assess the level of cellular stress in tissues and cells exposed to microgravity. Therefore, modulation of HSPs by drugs and genetic or environmental techniques could prove to be a potential therapeutic strategy to reduce the negative physiological consequences of long-duration spaceflight in astronauts.

Changes to human sleep architecture during long-duration spaceflight.

Both rapid eye movement and non-rapid eye movement sleep are important for cognitive function and well-being, yet few studies have examined whether human sleep architecture is affected by long-duration spaceflight. We recorded 256 nights of sleep from five crew members before (n = 112 nights), during (n = 83 nights) and after (n = 61 nights) ~6-month missions aboard the Mir space station, using the Nightcap sleep monitor. We compared sleep outcomes (including total sleep time, efficiency, latency, rapid eye movement and non-rapid eye movement) during spaceflight with those on Earth. We also evaluated longitudinal changes over time in space. We found that wakefulness increased by 1 hr in space compared with on Earth. Over time in space, rapid eye movement was initially reduced and then recovered to near preflight levels at the expense of non-rapid eye movement sleep. Upon return to Earth, sleep architecture returned to preflight distribution. Our findings suggest that spaceflight may alter sleep architecture and should be explored further.

Artificial gravity: an effective countermeasure for microgravity-induced headward fluid shift?

Long-duration spaceflight is associated with pathophysiological changes in the intracranial compartment hypothetically linked to microgravity-induced headward fluid shift. This study aimed to determine whether daily artificial gravity (AG) sessions can mitigate these effects, supporting its application as a countermeasure to spaceflight. Twenty-four healthy adult volunteers (16 men) were exposed to 60 days of 6° head-down tilt bed rest (HDTBR) as a ground-based analog of chronic headward fluid shift. Subjects were divided equally into three groups: no AG (control), daily 30-min intermittent AG (iAG), and daily 30-min continuous (cAG). Internal carotid artery (ICA) stroke volume (ICASV), ICA resistive index (ICARI), ICA flow rate (ICAFR), aqueductal cerebral spinal fluid flow velocity (CSFV), and intracranial volumetrics were quantified at 3 T. MRI was performed at baseline, 14 and 52 days into HDTBR, and 3 days after HDTBR (recovery). A mixed model approach was used with intervention and time as the fixed effect factors and the subject as the random effect factor. Compared with baseline, HDTBR was characterized by expansion of lateral ventricular, white matter, gray matter, and brain + total intracranial cerebral spinal fluid volumes, increased CSFv, decreased ICASV, and decreased ICAFR by 52 days into HBTBR (All Ps < 0.05). ICARI was only increased 14 days into HDTBR (P < 0.05). Neither iAG nor cAG significantly affected measurements compared with HDTBR alone, indicating that 30 min of daily exposure was insufficient to mitigate the intracranial effects of headward fluid shift. Greater AG session exposure time, gravitational force, or both are suggested for future countermeasure research.NEW & NOTEWORTHY Brief exposure to continuous or intermittent artificial gravity via short-arm centrifugation was insufficient in mitigating the intracranial pathophysiological effects of the headward fluid shift simulated during head-down tilt bed rest (HDTBR). Our results suggest that greater centrifugation session duration, gravitational force, or both may be required to prevent the development of spaceflight-associated neuro-ocular syndrome and should be considered in future ground-based countermeasure studies.

Biopsychosocial Health Considerations for Astronauts in Long-Duration Spaceflight: A Narrative Review.

Long-duration spaceflights beyond low-Earth orbit, including missions to the Moon and Mars, pose significant health risks. Although biomedical approaches commonly appear in the literature, considering psychological and social factors alongside physiologic health offers a more holistic approach to astronaut care. Integrating the biopsychosocial (BPS) framework into medical planning addresses complex spaceflight challenges and aids in developing mitigation strategies. This review examined health risks associated with long-duration spaceflight within a BPS framework. Sources included governmental space agencies, academic textbooks, and relevant publications from multiple databases. Considering the National Aeronautics and Space Administration's Human Research Program's 5 main hazards, a conceptual model was developed to highlight the multifactorial BPS effects of spaceflight. In space, astronauts face unique environments and biological adaptations, including fluid shift, plasma volume loss, bone density loss, and muscle atrophy. Noise and the absence of natural light disrupt circadian rhythms, causing sleep disturbances and fatigue, which affect physical and mental health. Studies on crews in isolated and confined extreme environments reveal psychosocial challenges, including impaired mood and cognition, interpersonal tension, and miscommunication. International collaboration in spaceflight introduces differences in communication, problem solving, and social customs due to diverse cultural backgrounds. Upcoming long-distance missions likely will amplify these challenges. This review emphasizes BPS health considerations in long-duration spaceflight. It highlights the interplay among psychological, social, and biological factors, advocating for multidisciplinary teams and a holistic approach to astronaut health and mission planning and the potential added value of BPS perspectives in considering countermeasures.

The MyoGravity project to study real microgravity effects on human muscle precursor cells and tissue

Microgravity (µG) experienced during space flights promotes adaptation in several astronauts’ organs and tissues, with skeletal muscles being the most affected. In response to reduced gravitational loading, muscles (especially, lower limb and antigravity muscles) undergo progressive mass loss and alteration in metabolism, myofiber size, and composition. Skeletal muscle precursor cells (MPCs), also known as satellite cells, are responsible for the growth and maintenance of muscle mass in adult life as well as for muscle regeneration following damage and may have a major role in µG-induced muscle wasting. Despite the great relevance for astronaut health, very few data are available about the effects of real µG on human muscles. Based on the MyoGravity project, this study aimed to analyze: (i) the cellular and transcriptional alterations induced by real µG in human MPCs (huMPCs) and (ii) the response of human skeletal muscle to normal gravitational loading after prolonged exposure to µG. We evaluated the transcriptomic changes induced by µG on board the International Space Station (ISS) in differentiating huMPCs isolated from Vastus lateralis muscle biopsies of a pre-flight astronaut and an age- and sex-matched volunteer, in comparison with the same cells cultured on the ground in standard gravity (1×g) conditions. We found that huMPCs differentiated under real µG conditions showed: (i) upregulation of genes related to cell adhesion, plasma membrane components, and ion transport; (ii) strong downregulation of genes related to the muscle contraction machinery and sarcomere organization; and (iii) downregulation of muscle-specific microRNAs (myomiRs). Moreover, we had the unique opportunity to analyze huMPCs and skeletal muscle tissue of the same astronaut before and 30 h after a long-duration space flight on board the ISS. Prolonged exposure to real µG strongly affected the biology and functionality of the astronaut’s satellite cells, which showed a dramatic reduction of responsiveness to activating stimuli and proliferation rate, morphological changes, and almost inability to fuse into myotubes. RNA-Seq analysis of post- vs. pre-flight muscle tissue showed that genes involved in muscle structure and remodeling are promptly activated after landing following a long-duration space mission. Conversely, genes involved in the myelination process or synapse and neuromuscular junction organization appeared downregulated. Although we have investigated only one astronaut, these results point to a prompt readaptation of the skeletal muscle mechanical components to the normal gravitational loading, but the inability to rapidly recover the physiological muscle myelination/innervation pattern after landing from a long-duration space flight. Together with the persistent functional deficit observed in the astronaut’s satellite cells after prolonged exposure to real µG, these results lead us to hypothesize that a condition of inefficient regeneration is likely to occur in the muscles of post-flight astronauts following damage.

The human body in different spaces

Space Medicine has revolutionized the way of understanding human physiology in extra-terrestrial environments, such as microgravity. Research in this field attempts to maintain synchrony between scientific and medical development, with the goal of improving the overall health and performance of astronauts. Engineering also plays a crucial role in the design of spacecraft and spacesuits to ensure the safety and health of astronauts on extended missions to the Moon and Mars. Radiation exposure in space poses health concerns, but strategies such as radiation control and shielding are being implemented to mitigate these risks. NASA is actively investigating how the human body reacts to long-duration spaceflight, with the goal of preparing for future extended space missions.

Percutaneous Cholecystostomy for Acute Cholecystitis During Spaceflight

INTRODUCTION: Acute calculous cholecystitis is a common surgical emergency and cholecystectomy is the gold-standard treatment. However, alternative drainage modalities such as percutaneous cholecystostomy tube (PCT) placement have been proposed for poor surgical candidates or in remote environments, such as space. We reviewed the literature to assess the theoretical utility of PCT to treat acute cholecystitis during long-duration spaceflight or on the Moon or Mars. METHODS: A systematic review of 16 peer-reviewed articles published since 2018 was completed to describe the terrestrial efficacy of PCT placement for acute calculous cholecystitis. RESULTS: The mean initial clinical success rate after PCT was 89.9% (range 82.2–100.0%). Duration of indwelling PCT ranged from median 6 to 58 d. Mean rate of recurrent cholecystitis was 15.8% (range 5.0–36.4%). A mean 35.6% of patients (range 18.0–61.0%) required interval cholecystectomy. Mean 30-d mortality was 9.6% (range 5.8–14.0%). A mean 18.6% of patients (range 7.2–30.0%) required repeat percutaneous intervention due to PCT placement complications. DISCUSSION: While PCT achieves high rates of early resolution of cholecystitis, the long-term outcomes after PCT are relatively poor, with risk of recurrent cholecystitis, need for cholecystectomy, and frequent postprocedural complications requiring repeat procedural interventions. In cislunar space, the return to Earth for cholecystectomy following PCT may be achieved, eliminating some of these concerns. However, with long-duration space travel such as a mission to Mars, PCT is likely inadequate for the long-term treatment of cholecystitis. Prophylactic cholecystectomy, developing surgical capabilities in space, or preflight screening ultrasound for cholelithiasis should be seriously considered for long-duration spaceflight. Lazow SP, Siu M, Brown L, Kamine TH. Percutaneous cholecystostomy for acute cholecystitis during spaceflight. Aerosp Med Hum Perform. 2024; 95(10):771–776.

DIANA: An underwater analog space mission

The DIANA mission represents an underwater analog space mission designed to simulate and study the impact of long-duration spaceflight and extraterrestrial habitation on crew performance, psychosocial dynamics, and technological systems. The mission utilized an underwater habitat, the Hydronaut H03 DeepLab, to mimic the isolated, confined, and extreme (ICE) environment of space. Over eight days, a six-member crew lived and worked in underwater (3) and water surface (3) habitats, performing scientific experiments and operational tasks. The mission schedule encompassed a variety of activities such as drone exploration, extravehicular activities (EVAs), soil sampling, and media interactions, culminating in a simulated departure from the lunar surface. Data collection methods included continuous biomedical monitoring, cognitive task assessments, and sociomapping to analyze team communication and cooperation. This paper provides an overview of the mission architecture and outcomes, offering valuable insights into the challenges of future human space exploration and informing improvements in crew selection, training, and support systems.

Liver tissue changes during and post 6-month spaceflight as measured by ultrasound radio frequency signal processing.

Analysis of ultrasound radio frequency (RF) signals allows for the determination of the index of reflectivity (IR), which is a new measure that is dependent on tissue properties. Previous work has shown differences in the IR of the carotid artery wall with long-duration spaceflight; therefore, it was hypothesized that liver tissue would also show differences in this measure with spaceflight. The RF signal of a liver tissue region of interest (ROI) was displayed and processed along six different lines covering a surface of approximately 2cm × 2cm. The IR was calculated as the energy backscattered by the liver ROI divided by the total energy returned to the ultrasound probe. Seven astronauts were investigated preflight, inflight on day 150, and postflight 4days and 6months after rerunning to Earth. Compared to preflight (63% ± 18%), the liver tissue ROI IR was significantly lower on flight day 150 (46% ± 14%; p = 0.027) and 4days postflight (46% ± 19%; p = 0.025). At 6months postflight, the IR returned to preflight values (59% ± 13%; p = 0.919). The significant decrease in the coefficient of reflectivity inflight and 4days postflight indicates an alteration in the liver tissue that reduces the reflection of ultrasound waves. This change in tissue properties could either be due to the addition of particles that do not reflect ultrasound waves or structural or cellular changes that alter the reflectivity of the tissue.

Spaceflight-induced contractile and mitochondrial dysfunction in an automated heart-on-a-chip platform

With current plans for manned missions to Mars and beyond, the need to better understand, prevent, and counteract the harmful effects of long-duration spaceflight on the body is becoming increasingly important. In this study, an automated heart-on-a-chip platform was flown to the International Space Station on a 1-mo mission during which contractile cardiac function was monitored in real-time. Upon return to Earth, engineered human heart tissues (EHTs) were further analyzed with ultrastructural imaging and RNA sequencing to investigate the impact of prolonged microgravity on cardiomyocyte function and health. Spaceflight EHTs exhibited significantly reduced twitch forces, increased incidences of arrhythmias, and increased signs of sarcomere disruption and mitochondrial damage. Transcriptomic analyses showed an up-regulation of genes and pathways associated with metabolic disorders, heart failure, oxidative stress, and inflammation, while genes related to contractility and calcium signaling showed significant down-regulation. Finally, in silico modeling revealed a potential link between oxidative stress and mitochondrial dysfunction that corresponded with RNA sequencing results. This represents an in vitro model to faithfully reproduce the adverse effects of spaceflight on three-dimensional (3D)-engineered heart tissue.

A common law in space for public health

Beyond the gravitational pull of Earth, space travel poses substantial public health hazards pertaining to the physical and mental well-being of astronauts and passengers, in addition to a possible threat to the populace of Earth upon re-entry. Exposure to cosmic radiation, cranial pressure from microgravity, weakened immunity to contagion, and the potential for depression and psychosis are all risks. Public health crises of this nature are to be expected as the duration of missions extends, as is the case with Mars settlement. In contrast to national space programmes, which have regarded these obstacles as human factors effecting the mission, public health law in common law British nations approaches them from the perspective of social justice and the preservation of human life and societal welfare. Countries including Australia, Canada, the United States, and the United Kingdom continue to apply traditional common law principles of public health law, which provide a sensible and enduring method for reconciling competing public and private interests. Common law permits the violation of civil liberties through the use of force in public health restraint, forced medication, and quarantine, but only if necessary, reasonable, and equitable. While the understanding of the health challenges associated with long-duration spaceflight may be in its infancy for national space programmes and civilian space ventures, the application of common law public health principles could aid in the establishment of health and safety protocols in which human reactions to crises in space resemble those observed on Earth. This may, nevertheless, necessitate the enactment of a more comprehensive federal public health statute. Embedded in both public health common law and international space law, the pre-eminence of preserving and respecting human life and well-being continues to be a cornerstone of humane justice despite the perilous conditions of space.

The human microbiome in space: parallels between Earth-based dysbiosis, implications for long-duration spaceflight, and possible mitigation strategies.

SUMMARYThe human microbiota encompasses the diverse communities of microorganisms that reside in, on, and around various parts of the human body, such as the skin, nasal passages, and gastrointestinal tract. Although research is ongoing, it is well established that the microbiota exert a substantial influence on the body through the production and modification of metabolites and small molecules. Disruptions in the composition of the microbiota-dysbiosis-have also been linked to various negative health outcomes. As humans embark upon longer-duration space missions, it is important to understand how the conditions of space travel impact the microbiota and, consequently, astronaut health. This article will first characterize the main taxa of the human gut microbiota and their associated metabolites, before discussing potential dysbiosis and negative health consequences. It will also detail the microbial changes observed in astronauts during spaceflight, focusing on gut microbiota composition and pathogenic virulence and survival. Analysis will then turn to how astronaut health may be protected from adverse microbial changes via diet, exercise, and antibiotics before concluding with a discussion of the microbiota of spacecraft and microbial culturing methods in space. The implications of this review are critical, particularly with NASA's ongoing implementation of the Moon to Mars Architecture, which will include weeks or months of living in space and new habitats.

The Case for Bisphosphonate Use in Astronauts Flying Long-Duration Missions.

Changes in the structure of bone can occur in space as an adaptive response to microgravity and on Earth due to the adaptive effects to exercise, to the aging of bone cells, or to prolonged disuse. Knowledge of cell-mediated bone remodeling on Earth informs our understanding of bone tissue changes in space and whether these skeletal changes might increase the risk for fractures or premature osteoporosis in astronauts. Comparisons of skeletal health between astronauts and aging humans, however, may be both informative and misleading. Astronauts are screened for a high level of physical fitness and health, are launched with high bone mineral densities, and perform exercise daily in space to combat skeletal atrophy as an adaptive response to reduced weight-bearing function, while the elderly display cellular and tissue pathology as a response to senescence and disuse. Current clinical testing for age-related bone change, applied to astronauts, may not be sufficient for fully understanding risks associated with rare and uniquely induced bone changes. This review aims to (i) highlight cellular analogies between spaceflight-induced and age-related bone loss, which could aid in predicting fractures, (ii) discuss why overreliance on terrestrial clinical approaches may miss potentially irreversible disruptions in trabecular bone microarchitecture induced by spaceflight, and (iii) detail how the cellular effects of the bisphosphonate class of drugs offer a prophylactic countermeasure for suppressing the elevated bone resorption characteristically observed during long-duration spaceflights. Thus the use of the bisphosphonate will help protect the bone from structural changes while in microgravity either along with exercise or alone when exercise is not performed, e.g. after an injury or illness.

Astrosense – a Printed Wearalbe Electrochemical Sensor for Monitoring Cortisol in Sweat during Human Spaceflight

The In Space Manufacturing of sensors and electronics can directly addresses the logistic challenge for long-duration human spaceflight missions by reducing mission logistics mass, increase reliability, mitigate risk, while also offering a high degree of customization and tailorability. This manufacturing approach relies on additive manufacturing technologies, due to its versatility, low power consumption, automation, fast manufacturing time with low waste generation, and ability to print a variety of materials. To ensure the health and safety of crew members, developing human health portable diagnostic tools that can be manufactured during long duration missions is necessary to ensure that the crew members are monitored in real time so that countermeasures can be deployed as soon as possible. Here we report the development of Astrosense (Figure 1), a wearable wireless and fully printed platform that integrates several sensors, including, electrochemical sensor for the detection of cortisol in sweat, temperature, CO2 and humidity sensors, as well as, the required hardware required to control each individual sensor.Astrosense consists of two sections, a reusable, and a disposable section. The reusable section contains the CO2,temperature, humidity sensor, the potentiostat that controls the cortisol sensor and the printed antennas for data transmission. The cortisol sensor, sweat harvest component and printed batteries will be located on the disposable section of Astrosense, so that they can be easily replaced once the sensor is either saturated, degraded or when the batteries need to be replaced. The disposable section will interfase with the reusable section of Astrosense through several medical grade adhesives and pogo pins. This allows for the easy replacement of the cortisol sensor as well as mounting and dismounting of the device on the human skin. Figure 1

Cardiovascular effects of long-duration space flight.

Early studies exploring the physiological effects of space travel have indicated the body's capacity for reversible adaptation. However, the impact of long-duration spaceflight, exceeding 6 months, presents more intricate challenges. Extended exposure to microgravity and radiation profoundly affects the CV system. Notable phenomena include fluid shifts toward the head and modified arterial pressure. These changes disrupt blood pressure regulation and elevate cardiac output. Additionally, the loss of venous compression leads to a reduction in central venous pressure. The displacement of fluid from the vascular system to the interstitium, driven by baroreceptor stimulation, results in a 10%-15% decline in plasma volume. Intriguingly, despite potential increases in cardiac workload, cardiac muscle atrophy and perplexing variations in hematocrit levels have been observed. The mechanism underlying atrophy appears to involve a shift in protein synthesis from the endoplasmic reticulum to the mitochondria via mortalin-mediated mechanisms. Instances of arrhythmias have been recurrently documented, although generally nonlethal, in both Russian and American space missions. Long-duration spaceflight has been associated with the prolongation of the QT interval, particularly in extended missions. Exposure of the heart to the proton and heavy ion radiation pervasive in deep space contributes to coronary artery degeneration, augmented aortic stiffness, and carotid intima thickening through collagen-mediated processes. Moreover, it accelerates the onset of atherosclerosis and triggers proinflammatory responses. Upon reentry, astronauts frequently experience orthostatic intolerance and altered sympathetic responses, which bear potential hazards in scenarios requiring rapid mobilization or evacuation. Consequently, careful monitoring of these cardiac risks is imperative for forthcoming missions. While early studies illuminate the adaptability of the body to space travel's challenges, the intricacies of long-duration missions and their effects on the CV system necessitate continued investigation and vigilance to ensure astronaut health and mission success.

Spaceflight associated dry eye syndrome (SADES): Radiation, stressors, and ocular surface health

Crewed spaceflight missions require careful scrutinization of the health risks including alterations to the tear film lipid layer in astronauts. We review the current literature and prior published work on tear film lipid layer biophysics and secondary spaceflight-associated dry eye syndrome (SADES). We define the term spaceflight-associated dry eye syndrome to describe the collection of ocular surface signs and symptoms experienced by astronauts during spaceflight. Our review covers the ocular surface and lipidomics in the spaceflight environment. From our literature review, we extrapolate biophysical principles governing the tear film layer to determine the changes that may arise from the harsh conditions of spaceflight and microgravity. Our findings provide vital information for future long-duration spaceflight, including a return to the Moon and potential missions to Mars.

Transcriptomic evidence of erythropoietic adaptation from the International Space Station and from an Earth-based space analog

Space anemia affects astronauts and the underlying molecular alterations remain unknown. We evaluated the response of erythropoiesis-modulating genes to spaceflight through the analysis of leukocyte transcriptomes from astronauts during long-duration spaceflight and from an Earth model of microgravity. Differential expression analysis identified 50 genes encoding ribosomal proteins with reduced expression at the transition to bed rest and increased during the bed rest phase; a similar trend was observed in astronauts. Additional genes associated with anemia (15 genes), erythrocyte maturation (3 genes), and hemoglobin (6 genes) were down-regulated during bed rest and increased during reambulation. Transcript levels of the erythropoiesis transcription factor GATA1 and nine of most enriched erythrocyte proteins increased at reambulation after bed rest and at return to Earth from space. Dynamic changes of the leukocyte transcriptome composition while in microgravity and during reambulation supported an erythropoietic modulation accompanying the hemolysis of space anemia and of immobility-induced anemia.

RTMS Ameliorates time-varying depression and social behaviors in stimulated space complex environment associated with VEGF signaling

Studies have indicated that medium- to long-duration spaceflight may adversely affect astronauts' emotional and social functioning. Emotion modulation can significantly impact astronauts' well-being, performance, mission safety and success. However, with the increase in flight time, the potential alterations in emotional and social performance during spaceflight and their underlying mechanisms remain to be investigated, and targeted therapeutic and preventive interventions have yet to be identified. We evaluated the changes of emotional and social functions in mice with the extension of the time in simulated space complex environment (SSCE), and simultaneously monitored changes in brain tissue of vascular endothelial growth factor (VEGF), matrix metalloproteinase-9 (MMP-9), and inflammation-related factors. Furthermore, we assessed the regulatory role of repetitive transcranial magnetic stimulation (rTMS) in mood and socialization with the extension of the time in SSCE, as well as examining alterations of VEGF signaling in the medial prefrontal cortex (mPFC). Our findings revealed that mice exposed to SSCE for 7 days exhibited depressive-like behaviors, with these changes persisting throughout SSCE period. In addition, 14 days of rTMS treatment significantly ameliorated SSCE-induced emotional and social dysfunction, potentially through modulation of the level of VEGF signaling in mPFC. These results indicates that emotional and social disorders increase with the extension of SSCE time, and rTMS can improve the performance, which may be related to VEGF signaling. This study offers insights into potential pattern of change over time for mental health issues in astronauts. Further analysis revealed that rTMS modulates emotional and social dysfunction during SSCE exposure, with its mechanism potentially being associated with VEGF signaling.

Cis-lunar and surface missions: Health risks and potential surgical conditions

The next goal of human space exploration is to return to the Moon to stay, and to establish a new, more advanced space station in lunar orbit: the ‘Lunar Gateway’. The authors aim to contribute to this goal through undertaking an ongoing comprehensive survey of relevant published scientific literature to seek information regarding the risk of medical conditions that might require operative or non-operative surgical solutions during long-duration spaceflight. The intended outcome is to create a roadmap for future mission planning. To date, we have identified more than 50 such potential surgical conditions. Based on disease severity and mission duration, these can be classified into: (Category 1) Time-critical conditions requiring immediate surgery; (Category 2) Urgent surgical conditions requiring minor temporising surgical intervention or conservative care (these patients can return to Earth for definitive treatment); or (Category 3) Non-urgent, as these conditions do not require immediate surgical intervention, and definitive treatment can be delayed. The proposed Lunar Gateway will be an international collaboration. Reaching Gateway is anticipated to take around three days. Gateway will operate in microgravity conditions, and include a communications lab (ground support from Earth is still available with minimal signal delay), a scientific lab, and a habitat for astronauts. Transfers to and from the lunar surface will allow astronauts to undertake extra-vehicular activities (EVA). Habitation on Gateway will present similar physiological and psychological challenges as experienced on the International Space Station (ISS), with the addition of a slightly increased communications lag. The Moon is only within Earth's magnetosphere for approximately 25 % of the time, which will increase space radiation exposure compared to the ISS. Gravitational conditions will range from microgravity on Gateway to ⅙ of the Earth's gravity on the lunar surface. Considering the duration and distance necessary in order to undertake a lunar mission, time-critical surgical interventions (Category 1) will likely be necessary, such as treating a bowel perforation, or fixation for musculoskeletal trauma. For urgent conditions (Category 2), antibiotic treatment of responsive appendicitis, drainage of uncomplicated cholecystitis, or other conservative measures might be acceptable as a temporising measure. If a return to Earth is possible within three days, delayed surgery can be undertaken if the conservative measures are unsuccessful, or the condition recurs. In the case of non-urgent procedures that can be delayed (Category 3), planned evacuation to Earth is expected to be available, for example, if a malignancy develops or is detected. Anticipating the medical and surgical challenges a lunar mission presents, and subsequent adequate planning and preparation for possible surgical emergencies, will help ensure mission success. Creating a system for triaging of surgical cases will be paramount in order to guide appropriate management.

Ultrasound Biomicroscopy as a Novel, Potential Modality to Evaluate Anterior Segment Ophthalmic Structures during Spaceflight: An Analysis of Current Technology.

Ocular health is currently a major concern for astronauts on current and future long-duration spaceflight missions. Spaceflight-associated neuro-ocular syndrome (SANS) is a collection of ophthalmic and neurologic findings that is one potential physiologic barrier to interplanetary spaceflight. Since its initial report in 2011, our understanding of SANS has advanced considerably, with a primary focus on posterior ocular imaging including fundus photography and optical coherence tomography. However, there may be changes to the anterior segment that have not been identified. Additional concerns to ocular health in space include corneal damage and radiation-induced cataract formation. Given these concerns, precision anterior segment imaging of the eye would be a valuable addition to future long-duration spaceflights. The purpose of this paper is to review ultrasound biomicroscopy (UBM) and its potential as a noninvasive, efficient imaging modality for spaceflight. The analysis of UBM for spaceflight is not well defined in the literature, and such technology may help to provide further insights into the overall anatomical changes in the eye in microgravity.