The Next Giant Leap for Space Human Factors: The Opportunities

OBJECTIVE

Propose areas of future space human factors research.

BACKGROUND

Deep space, long-duration human spaceflight missions to the Moon and Mars still require advances in space human factors research. Key drivers relate to astronauts living and working in isolation, new novel technologies required to accomplish exploration missions, and the longer durations of these.

RESULTS

Three areas of research are proposed for methods and techniques: (1) to enable more autonomous astronauts; (2) to monitor crew and improve ground team situation awareness; and (3) to detect and support changes in long-duration team coordination.

CONCLUSIONS

Future human exploration missions will benefit from advances in space human factors research.

APPLICATION

Human factors researchers can contribute to human spaceflight by prioritizing these research topics.

Neurocognitive assessment in microgravity: review of tools and benefits of increasing their clinical validity for long duration missions

INTRODUCTION

Clinical complications are not expected in current space missions; however, for future long-duration missions to the Moon and Mars, a new perspective may be needed - a more clinical approach. Different risks, both environmental, such as radiation, accidents, and biopsychological, including neurological problems, represent potential sources of subsequent neurocognitive deficits.

AIMS

This study aims to review research studies published to this date in microgravity conditions using existing spaceflight neurocognitive assessment batteries. This study also discusses the different risks of neuropsychological impairment in spaceflight and the potential benefits of increasing the clinical validity of these tools with neurological clinical samples on Earth for future long-duration missions.

METHOD

A PRISMA guidelines-based review of specialized literature on neurocognitive assessment batteries and human spaceflight was performed. Different factors including type of tool or battery used, sample size, mission duration, etc. were included in this review. After the scrutiny of 192 articles, a total of 27 studies were detailed in the review outcome.

RESULTS

Results showed that neuropsychological function research target has changed over the years, with working memory and perception studies being predominant in the 80s and 90s while reaction time being more frequent in recent research. We also found a lack of language-related research in microgravity and the predominance of two neurocognitive assessment batteries in microgravity research.

CONCLUSIONS

With this study, we want to emphasize the importance of increasing the clinical validity of neurocognitive or neuropsychological assessment tools to be used in space, especially in long-duration missions because in this type of mission the risk of suffering a brain injury or neurological condition increases due to multiple factors. Testing these tools with neurological clinical samples and using machine learning, predictive systems may help crews in early detection of potential clinical, neurological, or neurocognitive problems during these long-duration missions to Mars and beyond.

Neuropsychological considerations for long-duration deep spaceflight

The deep space environment far beyond low-Earth orbit (LEO) introduces multiple and simultaneous risks for the functioning and health of the central nervous system (CNS), which may impair astronauts' performance and wellbeing. As future deep space missions to Mars, moons, or asteroids will also exceed current LEO stay durations and are estimated to require up to 3 years, we review recent evidence with contemporary and historic spaceflight case studies addressing implications for long-duration missions. To highlight the need for specific further investigations, we provide neuropsychological considerations integrating cognitive and motor functions, neuroimaging, neurological biomarkers, behavior changes, and mood and affect to construct a multifactorial profile to explain performance variability, subjective experience, and potential risks. We discuss the importance of adopting a neuropsychological approach to long-duration deep spaceflight (LDDS) missions and draw specific recommendations for future research in space neuropsychology.

Space Medicine: Scientific Foundations, Achievements, and Challenges

This article, based on a report presented at the Scientific Session of the Russian Academy of Sciences, highlights the history of the formation of space medicine, its theoretical foundations, and the role of scientists of the Academy of Sciences in the preparation and implementation of the first manned flight into space. The achievements of domestic specialists in space physiology, biology, and medicine promoting the development of manned cosmonautics are considered. Examples are given of the implementation of the results of space research, as well as instruments and devices for medical support of space crews, into practical health care. The problems of medical support of future interplanetary flights and the ways of their solution are analyzed.

Earth-Based Research Analogs to Investigate Space-Based Health Risks

During spaceflight, astronauts are exposed to a variety of unique hazards, including altered gravity fields, long periods of isolation and confinement, living in a closed environment at increasing distances from Earth, and exposure to higher levels of hazardous ionizing radiation. Preserving human health and performance in the face of these relentless hazards becomes progressively more difficult as missions increase in length and extend beyond low Earth orbit. Finding solutions is a significant challenge that is further complicated by logistical issues associated with studying these unique hazards. Although research studies using space-based platforms are the gold standard, these are not without limitations. Factors such as the small sample size of the available astronaut crew, high expense, and time constraints all add to the logistical challenge. To overcome these limitations, a wide variety of Earth-based analogs, from polar research outposts to an undersea laboratory, are available to augment space-based studies. Each analog simulates unique physiological and behavioral effects associated with spaceflight and, therefore, for any given study, the choice of an appropriate platform is closely linked to the phenomena under investigation as well as the characteristics of the analog. There are pros and cons to each type of analog and each actual facility, but overall they provide a reasonable means to overcome the barriers associated with conducting experimental research in space. Analogs, by definition, will never be perfect, but they are a useful component of an integrated effort to understand the human risks of living and working in space. They are a necessary resource for pushing the frontier of human spaceflight, both for astronauts and for commercial space activities. In this review, we describe the use of analogs here on Earth to replicate specific aspects of the spaceflight environment and highlight how analog studies support future human endeavors in space.

The Potential of Physical Exercise to Mitigate Radiation Damage-A Systematic Review

There is a need to investigate new countermeasures against the detrimental effects of ionizing radiation as deep space exploration missions are on the horizon. Objective: In this systematic review, the effects of physical exercise upon ionizing radiation-induced damage were evaluated. Methods: Systematic searches were performed in Medline, Embase, Cochrane library, and the databases from space agencies. Of 2,798 publications that were screened, 22 studies contained relevant data that were further extracted and analyzed. Risk of bias of included studies was assessed. Due to the high level of heterogeneity, meta-analysis was not performed. Five outcome groups were assessed by calculating Hedges' g effect sizes and visualized using effect size plots. Results: Exercise decreased radiation-induced DNA damage, oxidative stress, and inflammation, while increasing antioxidant activity. Although the results were highly heterogeneous, there was evidence for a beneficial effect of exercise in cellular, clinical, and functional outcomes. Conclusions: Out of 72 outcomes, 68 showed a beneficial effect of physical training when exposed to ionizing radiation. As the first study to investigate a potential protective mechanism of physical exercise against radiation effects in a systematic review, the current findings may help inform medical capabilities of human spaceflight and may also be relevant for terrestrial clinical care such as radiation oncology.

Simulated Hypergravity Activates Hemostasis in Healthy Volunteers

Background

Hypergravity may promote human hemostasis thereby increasing thrombotic risk. Future touristic suborbital spaceflight will expose older individuals with chronic medical conditions, who are at much higher thromboembolic risk compared with professional astronauts, to hypergravity. Therefore, we tested the impact of hypergravity on hemostasis in healthy volunteers undergoing centrifugation.

Methods and Results

We studied 20 healthy seated men before and after 15 minutes under 3 Gz hypergravity on a long‐arm centrifuge. We obtained blood samples for hemostasis testing before, immediately after, and 30 minutes after centrifugation. Tests included viscoelastic thromboelastometry, platelet impedance aggregometry, endothelial activation markers, blood rheology testing, microparticle analyses, and clotting factor analysis. Exposure to hypergravity reduced plasma volume by 12.5% (P=0.002) and increased the red blood cell aggregation index (P<0.05). With hypergravity, thrombelastographic clotting time of native blood shortened from 719±117 seconds to 628±89 seconds (P=0.038) and platetet reactivity increased (P=0.045). Hypergravity shortened partial thromboplastin time from 28 (26–29) seconds to 25 (24–28) seconds (P<0.001) and increased the activity of coagulation factors (eg, factor VIII 117 [93–134] versus 151 [133–175] %, P<0.001). Tissue factor concentration was 188±95 pg/mL before and 298±136 pg/mL after hypergravity exposure (P=0.023). Antithrombin (P=0.005), thrombin‐antithrombin complex (P<0.001), plasmin‐alpha2‐antiplasmin complex (0.002), tissue‐plasminogen activatior (P<0.001), and plasminogen activator inhibitor‐1 (P=0.002) increased with centrifugation. Statistical adjustment for plasma volume attenuated changes in coagulation.

Conclusions

Hypergravity triggers low‐level hemostasis activation through endothelial cell activation, increased viscoelasticity, and augmented platelet reactivity, albeit partly counteracted through endogenous coagulation inhibitors release. Hemoconcentration may contribute to the response.

High-Intensity Interval Training: A Potential Exercise Countermeasure During Human Spaceflight

High-intensity interval training (HIT) is an effective approach for improving a range of physiological markers associated with physical fitness. A considerable body of work has demonstrated substantial improvements in cardiorespiratory fitness following short-term training programmes, while emerging evidence suggests that HIT can positively impact aspects of neuromuscular fitness. Given the detrimental consequences of prolonged exposure to microgravity on both of these physiological systems, and the potential for HIT to impact multiple components of fitness simultaneously, HIT is an appealing exercise countermeasure during human spaceflight. As such, the primary aim of this mini review is to synthesize current terrestrial knowledge relating to the effectiveness of HIT for inducing improvements in cardiorespiratory and neuromuscular fitness. As exercise-induced fitness changes are typically influenced by the specific exercise protocol employed, we will consider the effect of manipulating programming variables, including exercise volume and intensity, when prescribing HIT. In addition, as the maintenance of HIT-induced fitness gains and the choice of exercise mode are important considerations for effective training prescription, these issues are also discussed. We conclude by evaluating the potential integration of HIT into future human spaceflight operations as a strategy to counteract the effects of microgravity.

Galanin and Adrenomedullin Plasma Responses During Artificial Gravity on a Human Short-Arm Centrifuge

Galanin and adrenomedullin plasma responses to head-up tilt and lower body negative pressure have been studied previously. However, to what extent short-arm human centrifugation (SAHC) affects these responses is not known. In this study, we assessed how the application of variable gradients of accelerations (ΔGz ) via shifting of the rotation axis during centrifugation affects selected hormonal responses. Specifically, we tested the hypothesis, that cardiovascular modulating hormones such as galanin and adrenomedullin will be higher in non-finishers (participants in whom at least one of the pre-defined criteria for presyncope was fulfilled) when compared to finishers (participants who completed the entire protocol in both sessions) during SAHC exposure. Twenty healthy subjects (10 women and 10 men) were exposed to two g-levels [1 Gz and 2.4 Gz at the feet (Gz_Feet)] in two positions (axis of rotation placed above the head and axis of rotation placed at the heart level). Elevated baseline levels of galanin appeared to predict orthostatic tolerance (p = 0.054) and seemed to support good orthostatic tolerance during 1 Gz_Feet SAHC (p = 0.034). In finishers, 2.4 Gz_Feet SAHC was associated with increased galanin levels after centrifugation (p = 0.007). For adrenomedullin, the hypothesized increases were observed after centrifugation at 1 Gz_Feet (p = 0.031), but not at 2.4 Gz_Feet, suggesting that other central mechanisms than local distribution of adrenomedullin predominate when coping with central hypovolemia induced by SAHC (p > 0.14). In conclusion, baseline galanin levels could potentially be used to predict development of presyncope in subjects. Furthermore, galanin levels increase during elevated levels of central hypovolemia and galanin responses appear to be important for coping with such challenges. Adrenomedullin release depends on degree of central hypovolemia induced fluid shifts and a subject's ability to cope with such challenges. Our results suggest that the gradient of acceleration (ΔGz ) is an innovative approach to quantify the grade of central hypovolemia and to assess neurohormonal responses in those that can tolerate (finishers) or not tolerate (non-finishers) artificial gravity (AG). As AG is being considered as a preventing tool for spaceflight induced deconditioning in future missions, understanding effects of AG on hormonal responses in subjects who develop presyncope is important.

Regenerative medicine and 3D bioprinting for human space exploration and planet colonisation

3D printing also known as additive manufacturing (AM) is seen as one of the key enabling technologies for a large number of high-end industrial sectors including the automotive, aerospace and medical industry. Recent advances and breakthroughs in the last years have enabled 3D printing of biocompatible materials, cells and supporting components into complex 3D functional living tissues. 3D bioprinting is being applied to regenerative medicine, addressing the need for tissues and organs suitable for transplantation. Bioprinting implies additional complexities related to the sensitivities of living cells such as printing parameters and conditions, material selection, cell types etc. Despite these challenges, beating artificial heart cells, cartilage implants, skin repairs, functional kidney tissues have been printed successfully on Earth. The present paper addresses the possibility of performing regenerative medicine in space, which may guarantee sustainable life support on long term/long distance planetary exploration missions, opening to stable planet colonisation.

The Variable Vector Countermeasure Suit (V2Suit) for space habitation and exploration

The “Variable Vector Countermeasure Suit (V2Suit) for Space Habitation and Exploration” is a novel system concept that provides a platform for integrating sensors and actuators with daily astronaut intravehicular activities to improve health and performance, while reducing the mass and volume of the physiologic adaptation countermeasure systems, as well as the required exercise time during long-duration space exploration missions. The V2Suit system leverages wearable kinematic monitoring technology and uses inertial measurement units (IMUs) and control moment gyroscopes (CMGs) within miniaturized modules placed on body segments to provide a “viscous resistance” during movements against a specified direction of “down”—initially as a countermeasure to the sensorimotor adaptation performance decrements that manifest themselves while living and working in microgravity and during gravitational transitions during long-duration spaceflight, including post-flight recovery and rehabilitation. Several aspects of the V2Suit system concept were explored and simulated prior to developing a brassboard prototype for technology demonstration. This included a system architecture for identifying the key components and their interconnects, initial identification of key human-system integration challenges, development of a simulation architecture for CMG selection and parameter sizing, and the detailed mechanical design and fabrication of a module. The brassboard prototype demonstrates closed-loop control from “down” initialization through CMG actuation, and provides a research platform for human performance evaluations to mitigate sensorimotor adaptation, as well as a tool for determining the performance requirements when used as a musculoskeletal deconditioning countermeasure. This type of countermeasure system also has Earth benefits, particularly in gait or movement stabilization and rehabilitation.