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21st Century extravehicular activities: Synergizing past and present training methods for future spacewalking success
Abstract
Neil Armstrong's understated words, "That's one small step for man, one giant leap for mankind" were spoken from Tranquility Base forty years ago. Even today, those words resonate in the ears of millions, including many who had yet to be born when man first landed on the surface of the moon. By their very nature, and in the true spirit of exploration, extravehicular activities (EVAs) have generated much excitement throughout the history of manned spaceflight. From Ed White's first spacewalk in the June of 1965, to the first steps on the moon in 1969, to the expected completion of the International Space Station (ISS), the ability to exist, live and work in the vacuum of space has stood as a beacon of what is possible. It was NASA's first spacewalk that taught engineers on the ground the valuable lesson that successful spacewalking requires a unique set of learned skills. That lesson sparked extensive efforts to develop and define the training requirements necessary to ensure success. As focus shifted from orbital activities to lunar surface activities, the required skill set and subsequently the training methods changed. The requirements duly changed again when NASA left the moon for the last time in 1972 and have continued to evolve through the SkyLab, Space Shuttle, and ISS eras. Yet because the visits to the moon were so long ago, NASA's expertise in the realm of extra-terrestrial EVAs has diminished. As manned spaceflight again shifts its focus beyond low earth orbit, EVA's success will depend on the ability to synergize the knowledge gained over 40+ years of spacewalking to create a training method that allows a single crewmember to perform equally well, whether performing an EVA on the surface of the Moon, while in the vacuum of space, or heading for a rendezvous with Mars. This paper reviews NASA's past and present EVA training methods and extrapolates techniques from both to construct the basis for future EVA astronaut training.
... Cognitive performance is highly important for human safety while operating in extreme environments. This includes while being weightless in microgravity, experiencing altered ambient pressure due to aboveground heights, or underwater when diving in occupational or recreational settings (Martin et al., 2019;Miller, McGuire, & Feigh, 2017;Moore & Gast, 2010). As such, several studies have already investigated altered physics, optics, and elevated partial gas pressure on both physiology and psychology in submerged humans. ...
Objective
The intact cognitive processing capacity in highly demanding and dynamically changing situations (e.g., in extreme environmental conditions) is of central relevance for personal safety. This study therefore investigated whether underwater physical exercise (PE) affected cognitive performance by comparing these effects during underwater fin-swimming as opposed to inactivity under normal environmental conditions.
Background
Although acute bouts of PE can modulate cognitive performance under highly controlled and standardized laboratory conditions, no previous study has determined whether PE acutely modulates cognitive performance in non-laboratory testing conditions involving extreme environments (e.g., underwater).
Method
A total of 27 healthy volunteers (16 males and 11 females; 28.9 ± 7.4 years of age) participated in two experiments involving either moderate or high PE intensity. A PRE/POST crossover design was employed among participants while performing cognitive tests in a counterbalanced order (i.e., before and after 20 min of PE in submersion [WET] and once before and after inactivity [DRY] while in the laboratory). Cognitive performance was measured as a combination of executive functions through the Eriksen Flanker (inhibition) and Two-Back (working memory) Tasks using an underwater tablet computer.
Results
ANOVAs revealed enhanced reaction times only in the Flanker test after moderate PE for the WET condition. No other effects were detected.
Conclusion
These findings indicate that cognitive performance is exercise-intensity-dependent with enhanced effects during moderate PE, even in extreme environments (i.e., underwater).
Application
These results should be relevant in recreational and occupational contexts involving underwater activity and may also apply to microgravity (e.g., during extra-vehicular activities).
Description
This study compared the acute effects of physical exercise (PE) on cognitive performance in an underwater environment while participants fin-swam with SCUBA (self-contained underwater breathing apparatus) gear. Findings revealed that 20 min of moderate PE positively affected cognitive performance (i.e., inhibitory control ability). However, no changes were observed after high-intensity exercise.
... Examples of such facilities include the Neutral Buoyancy Lab (NBL) and Virtual Reality Lab. An overview of these facilities and more can be found in Ref. [33]. ...
Future human spaceflight missions will face the complex challenge of performing human extravehicular activity (EVA) beyond the low Earth orbit (LEO) environment. Astronauts will become increasingly isolated from Earth-based mission support and thus will rely heavily on their own decision-making capabilities and onboard tools to accomplish proposed EVA mission objectives. To better address time delay communication issues, EVA characters, e.g. flight controllers, astronauts, etc., and their respective work practices and roles need to be better characterized and understood. This paper presents the results of a study examining the EVA work domain and the personnel that operate within it. The goal is to characterize current and historical roles of ground support, intravehicular (IV) crew and EV crew, their communication patterns and information needs. This work provides a description of EVA operations and identifies issues to be used as a basis for future investigation.
... With the cancellation of the Apollo program, and the subsequent launch of Skylab in 1973, however, it became apparent that expanding EVA capabilities in orbit was essential. The success of Skylab itself hinged on the crews' ability to perform an EVA to repair a solar array that had been damaged during ascent [27]. This event brought the adaptability and utility of EVA to the forefront of mission design. ...
The notion of human exploration of a near-Earth object (NEO) is nothing new. Jules Verne wrote about this very idea in his story "Off on a Comet," first published in France in 1877. Since that time, a number of studies have examined NEO exploration for scientific purposes, in-situ resource utilization, mineralogical exploitation and even planetary defense; as early as 1966, a study was conducted to utilize the Apollo program hardware to fly by asteroid Eros 433 [32]. Yet there is very little in the literature archive addressing extra-vehicular activities operations on the surface of a near-Earth object. The arguments for manned missions to near-Earth objects have been presented in a number of papers, recognizing astronauts' adaptability to real-time challenges, the capability to collect geological samples while identifying the overall geological context, and the ability to return a great quantity of those geological samples to Earth, as just a few of the many reasons for a NEO manned mission. Few studies, however, have identified or discussed the myriad challenges of performing surface operations in an environment where the gravitation is considerably less than that of the Moon, but not negligible like the micro-gravity of an International Space Station (ISS) – based EVA. Using the operational experience learned from NASA's various human exploration programs, this paper will identify key challenges unique to NEO surface operations. Furthermore, this paper will map the applicable EVA tasks from both the Apollo program's lunar exploration missions and ISS construction to present an EVA operational concept for NEO surface exploration. Through mapping the applicable Apollo and ISS tasks to the surface of a NEO, relevant operational objectives and challenges are identified, and conceptual approaches to meeting the NEO EVA mission objectives and mitigating key risks are discussed.
With the completion of the Chinese space station, an increasing number of extravehicular activities will be executed by astronauts, which is regarded as one of the most dangerous activities in human space exploration. To guarantee the safety of astronauts and the successful accomplishment of missions, it is vital to determine the pose of astronauts during extravehicular activities. This article presents a monocular vision-based pose estimation method of astronauts during extravehicular activities, making full use of the available observation resources. First, the camera is calibrated using objects of known structures, such as the spacesuit backpack or the circular handrail outside the space station. Subsequently, the pose estimation is performed utilizing the feature points on the spacesuit. The proposed methods are validated both on synthetic and semi-physical simulation experiments, demonstrating the high precision of the camera calibration and pose estimation. To further evaluate the performance of the methods in real-world scenarios, we utilize image sequences of Shenzhou-13 astronauts during extravehicular activities. The experiments validate that camera calibration and pose estimation can be accomplished solely with the existing observation resources, without requiring additional complicated equipment. The motion parameters of astronauts lay the technological foundation for subsequent applications such as mechanical analysis, task planning, and ground training of astronauts.
Purpose In order to improve the operation efficiency and safety of the underwater manipulator, and study and solve the problem that the underwater training in the extravehicular activities of space stations is restricted by the size of the neutral buoyancy tank and is affected by complicated underwater environment. Methods The control simulation scheme of the underwater manipulator is proposed from the aspects of digital modeling, path simulation and collision detection to the manipulator and its operation object. Conclusion The control simulation module of the underwater manipulator and material object are mapped to realize virtual-real synchronization, which can not only simulate the motion trajectory of the underwater manipulator, but also quickly detect collision and vividly simulate underwater operation conditions. The underwater training results shows that the path simulation results of the underwater manipulator is consistent with the reality, and the collision detection is efficient, which greatly improves the underwater training efficiency and safety, and smoothly ensures completion of underwater training mission of the astronaut crew from space station SZ-12 to SZ-15.KeywordsUnderwaterManipulatorControl simulation
With the lunar base, crewed Mars exploration and other future exploration plans proposed, the thermal control system of spacecraft will face challenges such as significantly higher thermal load and more complex and variable thermal environment. Traditional radiant heat sinks can hardly cope with the more demanding heat rejection requirements brought by these challenges, and more efficient, reliable and robust heat sinks are urgently needed to ensure the smooth running of future exploration programs. The sublimation or evaporation cooling technology has great potential to respond to these potential thermal control challenges. They utilize the latent heat of phase change from sublimation or evaporation of the consumable working medium into the space environment to reject the waste heat generated by the crew or equipment inside the spacecraft. This paper presents a review of the research progress in recent decades around two typical consumable heat sinks, the water sublimator and the water membrane evaporator. It mainly covers the basic issues and recent advances in component configuration, analytical and computational methods, experimental research methods, and system application architecture. The remaining problems and potential solutions in the development of water sublimator and water membrane evaporator as well as the direction of future development are summarized and pointed out.
To meet requirements of underwater simulation training for space station mission, the safety problem of underwater operation of the robotic arm is studied and solved. Methods. Based on the environment adaptability, operation control and man-machine interaction of the underwater robotic arm, the safety design scheme is proposed. Conclusion. The underwater test shows that the safety design of the underwater robotic arm is comprehensive and the measures are effective. The operation ability of the underwater robotic arm is guaranteed in the special Man-Machine-Environment relationship composed of the astronaut in the underwater training suit, the underwater robotic arm and the neutral buoyancy tank. From the perspective of the whole underwater simulation training effect, it not only improves the efficiency, but also improves the quality in the underwater simulation training because it is closer to the real space operation conditions, so as to achieve the expected goal of safety, efficiency and economy.
The paper considers the topical areas of applying VR environment in the pro-cess of training cosmonauts to perform extravehicular activities. The tasks that can be solved using virtual reality are defined. The paper gives a descrip-tion of operations and scenarios for which it is possible to use virtual reality systems. The stages of cosmonaut training, at which it is advisable to apply the results of the defined tasks, are determined.
To meet requirements of training astronauts for space task on ground, robotic arm working underwater is researched. Methods The solution to the underwater robotic arm is proposed by research on the robotic arm’s major structure, drive and control, neutral buoyancy design, sealing, corrosion resistance, and so on. Conclusion Through the modeling and simulation, underwater robotic arm owned rational structure, stable control system, and has the ability to cover the working space. Furthermore, underwater sealing means has passed the test. Consequently, the method to develop underwater robotic arm is feasible and reasonable.
In terms of space travel, many of the limitations faced by humans, in stand-alone form, are removed simply by the adoption of a cyborg persona, particularly in terms of neural upgrading. In this article, a look is taken at different types of brain–computer interface that can be employed to realize cyborgs as biology–technology hybrids. The approach taken is very practical, with actual space application in mind, although some wider implications are also considered. Results from experiments are discussed in terms of their meaning and application possibilities. The article takes a scientific experimental approach, opening up realistic possibilities in the future of space travel, rather than providing conclusive comments on the technologies employed. Human implantation and the merger of biology and technology are important elements to the overall scheme.
Objective: To improve the current extravehicular activity facility, new gravity compensation technology is researched. Methods: To assure the rapidity and precision of gravity compensation, high torque motor and low torque motor cooperation are applied to generate contragravity; to offload the maximum added mass, the system tracks the target position actively by servo control; to meet astronaut specific needs of extravehicular activity, the ingenious lift spreader of suspension system is designed. Results: Design analysis and model verification show that the position track error is less than 10 mm and the accuracy of the single suspended cable tension force is 99.5 % at the maximum limit of 0.1 m/s velocity and 0.1 m/s2 acceleration. Conclusion: The facility that applied new gravity compensation technology is able to generate near-zero microgravity environment, which is more suitable for training of extravehicular activity.
Extravehicular Activity (EVA) is an essential component to allow for future human lunar exploration to succeed. Key design and development considerations for future lunar EVA needs will be investigated. Extravehicular mobility units (EMUs), spacesuits, with increased capabilities and flexibilities in their use will be required, containing the ability to withstand the lunar environment. Issues investigated in relation to EVA suit design include lunar dust. This in particular would pose a hazard to a human rated mission to the Moon and will be examined. A solution must be found for the abrasion of Apollo astronauts' spacesuits whilst taking part in lunar EVA. This abrasion affected both pressure retention and impaired visibility. Additional exposure to fine-grained particles of lunar dust has been indicated to be the cause of numerous health problems for the astronauts. These factors must be taken into account during the design process of an EVA suit for use on the lunar surface along with dust mitigation technologies. A robust training scheme forms the basis for a successful mission. The first step towards developing the needed infrastructure for exploration extravehicular activity (EVA) training is to define and understand the EVA operations that will be required to achieve lunar exploration. A review of Apollo and International Space Station (ISS) lessons learned, concerning EVA operations and training is conducted. Analyses from this review are modified in the context of future exploration missions, including the International Space Exploration Committee Group (ISECG) reference architectures. Recommendations for EVA suit design and training operational procedures are suggested, based on the aforementioned review and tailored modifications towards human exploration. Initial theories to develop these designs and recommendations will be presented based on my conclusions and successive independent analysis.
An exoskeleton robotic system based on the passive gravity compensation technique is proposed to assist the physical simulation of reduced-gravity locomotion for the on-earth training of astronauts walking on the moon or Mars. This innovative simulation system based on the exoskeleton robotics and the passive gravity compensation technique is composed of a treadmill and a wearable passive exoskeleton mechanism for balancing any amount (from 0% to 100%) of the gravity of human body and its limbs so that a person wearing such a passive exoskeleton will experience a realistic reduced gravity feeling when he/she moves in the treadmill. Because the proposed exoskeleton robot is completely passive, no active joint control torques are required, and it need not to consider the problem of joint control system design and its stability issue. Dynamics simulation results demonstrate that the proposed passive exoskeleton robotic simulator is capable of simulating reduced gravity locomotion for astronaut in different levels of gravity.
In the near future, accessibility to space will be opened to anyone with the means and the desire to experience the weightlessness of microgravity, and to look out upon both the curvature of the Earth and the blackness of space, from the protected, shirt-sleeved environment of a commercial spacecraft. Initial forays will be short-duration, suborbital flights, but the experience and expertise of half a century of spaceflight will soon produce commercial vehicles capable of achieving low-Earth orbit. Even with the commercial space industry still in its infancy, and manned orbital flight a number of years away, little doubt exists that there will one day be a feasible and viable market for those courageous enough to venture outside the vehicle wearing nothing but a spacesuit, with nothing but preflight training to rely upon. What that Extravehicular Activity (EVA) preflight training entails, however, has yet to be defined. While a number of significant factors will influence the composition of a commercial EVA training program, a fundamental question remains: "what minimum training standards must be met to ensure a safe and successful commercial spacewalk?" Utilizing the experience gained through NASA's Skills program - designed to qualify NASA and International Partner astronauts for EVA aboard the Space Shuttle and International Space Station - this paper identifies the attributes and training objectives essential to the safe conduct of an EVA, and attempts to conceptually design a comprehensive training methodology meant to represent an acceptable qualification standard.
This report describes the theoretical and operational foundations for our analysis of skill in extravehicular mass handling. A review of our research on postural control, human-environment interactions, and exploratory behavior in skill acquisition is used to motivate our analysis. This scientific material is presented within the context of operationally valid issues concerning extravehicular mass handling. We describe the development of meaningful empirical measures that are relevant to a special class of nested control systems: manual interactions between an individual and the substantial environment. These measures are incorporated into a unique empirical protocol implemented on NASA's principal mass handling simulator, the precision air-bearing floor, in order to evaluate skill in extravehicular mass handling. We discuss the components of such skill with reference to the relationship between postural configuration and controllability of an orbital replacement unit, the relationship between orbital replacement unit control and postural stability, the relationship between antecedent and consequent postural movements. Finally, we describe our expectations regarding the operational relevance of the empirical results as it pertains to extravehicular activity tools, training, monitoring, and planning.
Focused interviews were conducted with the Apollo astronauts who landed on the moon. The purpose of these interviews was to help define extravehicular activity (EVA) system requirements for future lunar and planetary missions. Information from the interviews was examined with particular attention to identifying areas of consensus, since some commonality of experience is necessary to aid in the design of advanced systems. Results are presented under the following categories: mission approach; mission structure; suits; portable life support systems; dust control; gloves; automation; information, displays, and controls; rovers and remotes; tools; operations; training; and general comments. Research recommendations are offered, along with supporting information.
Defining the goals for future human space endeavors is a challenge now facing all spacefaring nations. Given the high costs and associated risks of sending humans into Earth orbit or beyond - to lunar or Martian environments, the nature and extent of human participation in space exploration and habitation are key considerations. Adequate protection for humans in orbital space or planetary surface environments must be provided. The Space Shuttle, Mir Space Station, Salyut-Soyuz, and Apollo programs have proven that humans can perform successful extravehicular activity (EVA) in microgravity and on the Lunar surface.
This report documents the results of a study carried out as part of NASA s Revolutionary Aerospace Systems Concepts Program examining the future technology needs of extravehicular activities (EVAs). The intent of this study is to produce a comprehensive report that identifies various design concepts for human-related advanced EVA systems necessary to achieve the goals of supporting future space exploration and development customers in free space and on planetary surfaces for space missions in the post-2020 timeframe. The design concepts studied and evaluated are not limited to anthropomorphic space suits, but include a wide range of human-enhancing EVA technologies as well as consideration of coordination and integration with advanced robotics. The goal of the study effort is to establish a baseline technology "road map" that identifies and describes an investment and technical development strategy, including recommendations that will lead to future enhanced synergistic human/robot EVA operations. The eventual use of this study effort is to focus evolving performance capabilities of various EVA system elements toward the goal of providing high performance human operational capabilities for a multitude of future space applications and destinations. The data collected for this study indicate a rich and diverse history of systems that have been developed to perform a variety of EVA tasks, indicating what is possible. However, the data gathered for this study also indicate a paucity of new concepts and technologies for advanced EVA missions - at least any that researchers are willing to discuss in this type of forum.
Preparing astronauts to perform the many complex extravehicular activity (EVA) tasks required to assemble and maintain Space Station will be accomplished through training simulations in a variety of facilities. The adequacy of this training is dependent on a thorough understanding of the task to be performed, the environment in which the task will be performed, high-fidelity training hardware and an awareness of the limitations of each particular training facility. Designing hardware that can be successfully operated, or assembled, by EVA astronauts in an efficient manner, requires an acute understanding of human factors and the capabilities and limitations of the space-suited astronaut. Additionally, the significant effect the microgravity environment has on the crew members' capabilities has to be carefully considered not only for each particular task, but also for all the overhead related to the task and the general overhead associated with EVA. This paper will describe various training methods and facilities that will be used to train EVA astronauts for Space Station assembly and maintenance. User-friendly EVA hardware design considerations and recent EVA flight experience will also be presented.
This review of astronaut extravehicular activity (EVA) and the details of American and Soviet/Russian spacesuit design focuses on design recommendations to enhance astronaut safety and effectiveness. Innovative spacesuit design is essential, given the challenges of future exploration-class missions in which astronauts will be called upon to perform increasingly complex and physically demanding tasks in the extreme environments of microgravity and partial gravity.
In the 36 years between June 1965 and February 2001, the US human space flight program has conducted 100 spacewalks, or extravehicular activities (EVAs), as NASA officially calls them. EVA occurs when astronauts wearing spacesuits travel outside their protective spacecraft to perform tasks in the space vacuum environment. US EVA started with pioneering feasibility tests during the Gemini Program. The Apollo Program required sending astronauts to the moon and performing EVA to explore the lunar surface. EVA supported scientific mission objectives of the Skylab program, but may be best remembered for repairing launch damage to the vehicle and thus saving the program. EVA capability on Shuttle was initially planned to be a kit that could be flown at will, and was primarily intended for coping with vehicle return emergencies. The Skylab emergency and the pivotal role of EVA in salvaging that program quickly promoted Shuttle EVA to an essential element for achieving mission objectives, including retrieving satellites and developing techniques to assemble and maintain the International Space Station (ISS). Now, EVA is supporting assembly of ISS. This paper highlights development of US EVA capability within the context of the overarching mission objectives of the US human space flight program.
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Walking to Olympus: an EVA chronology
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Image from a Desert Rats trial in the desert of Arizona
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Fig. 14. Image from a Desert Rats trial in the desert of Arizona. Source: Image from http://humanresearch.jsc.nasa.gov/analogs/analog_ drats.asp. Fig.
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