Slopes along Apollo EVAs: Astronaut experience as input for future mission planning

Modeling a 15-min extravehicular activity prebreathe protocol using NASA׳s exploration atmosphere (56.5 kPa/34% O2)

NASA's upcoming return to the moon includes a plan for longer duration lunar missions that prioritize science and surface exploration. The current Artemis Base Camp reference proposes a Surface Habitat (SH) that will support 2 to 4 crewmembers with adequate capability for living and working for 30 days or more. An important aspect of the SH's design will be its ability to support a high frequency of Extravehicular Activities (EVAs) for scientific and operational purposes. There are multiple EVA access options that can support EVA access from the SH to the lunar surface. This paper explores three unique options for EVA access: a traditional airlock, a suitlock, and a suitport-airlock. A traditional airlock utilizes a segregated, variable pressure volume, accessed by use of internal and external hatches, to provide EVA access. The airlock volume must be depressurized and repressurized for every EVA. A suitlock is similar in operation to the airlock, utilizing a segregated volume that is depressurized and repressurized for every EVA. However, in this case the suits are donned/doffed through a suitlock interface installed in the airlock bulkhead. EVA suits in a suitport-airlock are accessed through suitport interfaces that are installed in the airlock bulkhead as well, but the suitport-airlock stays in vacuum while the suits themselves remain pressurized, and the airlock does not have to be depressurized and repressurized for each EVA. This study also evaluated the use of an airlock airsave system in conjunction with the traditional airlock and suitlock cases. This system captures a fraction of the airlock gas instead of venting all of the gas pre-EVA. The captured gas is then used to partially repressurize the airlock post-EVA. In this study, each option is evaluated based on six different areas of analysis. The metrics include overhead time for EVAs, dust mitigation, consumables for resupply mass, system mass, safety and mission assurance, and programmatic considerations. The EVA access options are evaluated and compared under each area of analysis. The baseline case assumes the SH operates at 8.2 psia.

Protecting Lunar Colonies From Space Radiation

NASA's projected return to the lunar surface with the Artemis program opens the possibility for technological developments that maximize human exploration in ways that were unimaginable during the Apollo program. Specifically, the implementation of heads-up displays (HUD) has the potential to greatly increase astronaut performance during extravehicular activities (EVA) by increasing their situational awareness, providing relevant scientific resources, and presenting live personal biometric data that can safeguard mission success and astronaut health. Though they are an excellent mechanism for conveying information without incurring unnecessary physical strain, the implementation of heads-up displays in the vacuum of space presents challenges including: illumination variance; brightness; contrast; interface control mechanisms; and the general volume of data that can be conveyed without inducing cognitive burnout through clutter. To satisfy the desire to improve astronaut performance with HUDs while also accounting for the above design challenges, ALEXEI, short for Augmented Lunar Exploration and Extravehicular Interface, was developed in the Embry-Riddle Aeronautical University (ERAU) Spacesuit Utilization of Innovative Technology Laboratory (S.U.I.T. Lab) to be an augmented reality interface that can enhance an astronauts ability to conduct successful, scientifically relevant EVAs on the lunar surface. The resulting deliverable was created for the 2020 NASA SUITS (Spacesuit User Interface Technologies for Students) Challenge and balances features that past and current astronauts have expressed a functional desire for while also being cautious of human limitations in terms of visualizing and synthesizing information. Those features include a simplistic visual appearance, which displays a breadth of information that monitors mission progress, provides detailed instructions of mission tasks, and displays biometric vital signs, while only requiring a minimalistic level of input control. Future development of this system will include implementing silent speech control (sponsored by the ERAU Office of Undergraduate Research), which reduces the amount of physical strain needed to control the interface, a robust navigational aid, and user testing in a high-fidelity environment to confirm the usability of the interface. Continued refinement of this device will meet 2021 NASA SUITS Challenge objectives and continue the S.U.I.T. Lab's mission of human-centric design to aid in exploration of the cosmos. The following paper will discuss the history of EVA mission architecture, current methodologies used to aid astronauts on EVA, demonstrate the need for AR display technology in an EVA environment, describe the human factors principles that guided the design of ALEXEI, and discuss the plans for future development and testing.

Extravehicular activity (EVA) is a highly hazardous phase of human spaceflight, yet one of the most scientifically rewarding. Ensuring the safety, efficiency, and autonomy of astronauts is essential for the success of Artemis mission EVAs. Prior work has developed automated EVA planning tools, but none incorporate monitoring of physiological data. The Navigational Ground Assessment & Trajectory Optimization Router (NaviGATOR) is designed to process surface environment data, physiological data, consumables levels, and preselected scientific regions of interest (ROI) to determine the EVA path that minimizes astronaut energy expenditure and maximizes scientific return. First, a grid-based representation of the lunar surface is constructed from slope data. Metabolic rate (MR) is predicted for each grid cell using slope data, locomotion speed, and mass of the astronaut-suit system. Grid cells with slopes that exceed allowable ranges as defined in Exploration EVA System's Concept of Operations are constrained as unusable. All other grid cells are assigned a normalized cost based on MR predictions. Once the coordinates of start points, end points, and ROIs are provided, the tool uses mixed integer linear programming to determine the optimal ordering of ROI visits. Optimal Rapidly-exploring Random Trees planpaths between ROIs to minimize energy expenditure while satisfying constraints. The tool can plan paths both before an EVA and adjust paths during EVA based on astronaut vital signs and suit consumable levels, thus facilitating better-informed mission planning and improving crew autonomy. The tool's performance was validated through comparison to Apollo EVAs, which showed that the tool orders ROIs identically to visitation order by Apollo astronauts, plans paths between ROIs similar to those the Apollo astronauts traversed, and predicts MRs comparable to Apollo mission-recorded data. Overall, this tool may be able to improve safety, efficiency, and autonomy of astronauts on surface EVAs. NaviGATOR is maintained on a public GitHub repository.

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.

<div class="htmlview paragraph">An extravehicular activity (EVA) path-planning and navigation tool, called the Mission Planner, has been developed to assist with pre-mission planning, scenario simulation, real-time navigation, and contingency replanning during astronaut EVAs, The Mission Planner calculates the most efficient path between user-specified waypoints. Efficiency is based on an exploration cost algorithm, which is a function of the estimated astronaut metabolic rate. Selection of waypoints and visualization of the generated path are realized within a 3D mapping interface through terrain elevation models. The Mission Planner is also capable of computing the most efficient path back home from any point along the path.</div>

Spaceflight research has seen an increased focus on developing models of astronaut health, operational readiness, and cognitive states from physiological data during astronaut operations. In particular, astronaut monitoring during extravehicular activities (EVAs) will become increasingly important for future deep space exploration missions to the Moon and Mars with reduced reliance on Earth-based support. A primary challenge in developing models is the ability to collect sufficient, representative sample data in realistic operational settings, and models developed to date have been constrained to using human data collected in laboratory settings. Spacesuit simulators offer a means to collect data in experimental settings on simulated EVA, but a suite of physiological and behavioral sensors and data acquisition has yet to be incorporated into simulated spacesuits. As a result, existing models remain unvalidated in representative environments. Without providing human participants with similar ecological constraints and validity, models trained on lab-based data may not generalize to field EVA operations. To address these gaps, this work presents the development and validation of a spacesuit simulator capable of collecting behavioral, physiological (including neural) data during naturalistic simulated EVAs. Specifically, the spacesuit simulator enables the collection of speech and navigation data as well as functional near-infrared spectroscopy and eye-tracking, recorded from in-suit sensors by embedding data acquisition hardware within the portable life support system. To simulate teaming constraints, the helmet ventilation system forces communication to be mediated by technological devices. Finally, these suits accommodate diverse anthropometries (5th percentile female to 95th percentile male) to enable the collection of generalizable sample datasets. Following fabrication, the collection of these physiological data for future model development was validated in dyads during simulated EVA surface operations.

<div class="htmlview paragraph">In the course of Extravehicular Activity (EVA) throughout the Shuttle program, crewmembers have been required to handle moving objects. Future Shuttle missions, such as the Hubble Space Telescope repair and Space Station Freedom assembly missions, will require manipulation of objects much larger than the crewmember. This activity imparts loads into the crewmember, his Extravehicular Mobility Unit (EMU), and the foot restraint. Historically, the space suit restraint manload requirements have been based solely on the loads that an astronaut could impart using isometric strength. Manned testing was performed at the Johnson Space Center to determine the maximum loads that could be imparted on the EMU as a result of handling large objects.</div> <div class="htmlview paragraph">This paper is an overview of the testing performed to define maximum loads on the EMU as a result of handling massive objects. Test results and the impact on EMU design are reviewed. The effect of suit arm span sizing on maximum loading is examined.</div>

<p>Astronaut nutrition is an important aspect to consider for extra-terrestrial missions. It encompasses microbiological risks for humans, individual nutritional needs and the social well-being of astronauts. During a two-week analogue astronaut mission to the Moon, research focusing on the dietary needs and health of each crew member was performed. A crew of six analog astronauts, from the EuroMoonMars IMA HI-SEAS II (EMMIHS-II) mission followed a pre-prepared personal menu based on their intolerances and daily activities. </p><p>The first things that needed to be considered was the sanitary aspect of the missions, as it severely limits food choices. Fresh foods that are consumed on Earth are microbiologically fragile and occupy an important conservation space air. In order to ensure food safety and optimize storage space, the only food taken on the EMMIHS-II mission was freezedried.</p><p>Prior to the mission, the food rations and distribution amongst crewmembers was determined according to the average nutritional and calorific needs of the group. To maintain a basal metabolism, a balanced nutrition is required. A healthy and sufficient food intake is of high importance, particularly due to the regular physical activity each crewmember performs during Extra Vehicular Activities (EVAs) that the crew performed daily.</p><p>It was not possible to determine the actual amount of energy consumed on a daily basis during this mission for logistical reasons. It was also not possible to weigh out the food for each individual crewmember, as it would have taken up too much of the mission time. In the future, portions could be determined in terms of “cup sizes” per person, as this would be the most realistic measure for the preparation of freeze-dried food. </p><p>Furthermore, various digestive problems have been identified throughout this mission. Possible explanations for these issues could be a too abrupt change of eating habits including the lack of consumption of fresh fruits, fresh vegetables and the lack of fiber-rich cereals. In order to avoid this on future missions, the next strategy could be to first estimate the dietary intake of vegetable fibre for each individual before the mission start, in order to individually adapt the fruit and vegetable ration recommendations.</p><p>A diverse distribution of culinary recipes is also recommended for the preparation of future missions, in order to improve the taste of the meals for the crew. Taste is an important part of the pleasure of eating and as a result, it heavily influences the intake of food. This inevitably has an effect on the physical and mental well-being of the crew.</p><p>Finally, the social and psychological aspect of food plays an important role in the mental well-being of the astronauts. In this context, it was found that the food preparation and meal-sharing moments enabled the team to strengthen their social ties, which was in favour of their fulfilment. However, on the other hand, pleasure from eating and each crewmembers’ appetite did often not correspond to this. Hence, it was found that the freezedried food did not contribute to the emotional wellbeing of the astronauts.</p>

Humans have dreamed of exploring Mars for many years. However, the recent mandate by President Bush directing NASA to send humans to Mars (after first returning to the moon) has transformed the work in planetary exploration from the realm of paper studies and theory back into the realm of a near-term reality [4]. As humans prepare to venture out of low Earth orbit, robots will be integral teammates in this endeavor, if for no other reason than size of the area to be explored. The moon has a surface area approximately the size of the continents of North and South America combined, and Mars has a surface area approximately the size of the entire land mass of Earth. Because of the shear scale of this exploration area (and the limited number of humans who will be able to visit on any given mission), robots will be involved in any realistic exploration scenario. Many of these robots will operate on their own (or with other robots) and never work alongside humans. However, other robots (akin to the lunar rovers used during the later Apollo missions) will be specifically designed to assist humans and maximize their effectiveness during Extravehicular Activities (EVAs). These robots will afford the astronauts the mobility to explore much larger areas of the surface than they would be able to reach on their own, allow them to transport scientific equipment, and provide task assistance at several levels. Commands sent from Earth cannot travel faster than the speed of light, and data/images from the robots are also subject to this limit. This intergalactic speed limit leads to minimum round trip signal delays between Earth and the moon of about 2.5 sec, and for Mars the time varies from about 8 to 42 minutes, depending on the planetary alignment. Because of these delays, robots will be most effective if they primarily receive high level commands and goals from Earth. Deploying robots capable of accepting high level commands will require them to be more self-sufficient (and self-monitoring) so that they can work autonomously to achieve those high level goals. Designing these autonomous mobile robots will require careful planning and utilize a wide range of engineering and scientific disciplines/technologies which are currently in various stages of maturity. All robots intended to be used as human assistants will need to be designed to maximize the effectiveness of EVAs. Furthermore, these robots must be safe around

<div class="htmlview paragraph">During the first two weeks of September 2005, the National Aeronautics and Space Administration (NASA) Johnson Space Center (JSC) Advanced Extravehicular Activity (AEVA) team led the field test portion of the 2005 Research and Technology Studies (RATS). The Desert RATS field test activity is the culmination of the various individual science and advanced engineering discipline areas year-long technology and operations development efforts into a coordinated field test demonstration under representative (analog) planetary surface terrain conditions. The purpose of the RATS is to drive out preliminary exploration concept of operations EVA system requirements by providing hands-on experience with simulated planetary surface exploration extravehicular activity (EVA) hardware and procedures. The RATS activities also are of significant importance in helping to develop the necessary levels of technical skills and experience for the next generation of engineers, scientists, technicians, and astronauts who will be responsible for realizing the goals of the Constellation Program.</div> <div class="htmlview paragraph">The 2005 Desert RATS was the eighth RATS field test and was the most systems-oriented, integrated field test to date with participants from NASA field centers, the United States Geologic Survey (USGS), industry partners, and research institutes. Each week of the test, the 2005 RATS addressed specific sets of objectives. The first week focused on the performance of surface science astro-biological sampling operations, including planetary protection considerations and procedures. The second week supported evaluation of the Science, Crew, Operations, and Utility Testbed (SCOUT) prototype rover and its sub-systems. Throughout the duration of the field test, the Communications, Avionics, and Infomatics pack (CAI-pack) was tested. This year the CAI-pack served to provide information on surface navigation, science sample collection procedures, and EVA timeline awareness. Additionally, 2005 was the first year since the Apollo program that two pressurized suited test subjects have worked together simultaneously. Another first was the demonstration of recharge of cryogenic life support systems while in-use by the suited test subjects. The recharge capability allowed the simulated EVA test duration to be doubled, facilitating SCOUT proto-type rover testing. This paper summarizes Desert RATS 2005 test hardware, detailed test objectives, test operations and test results.</div>

The tools that the astronauts used during the Apollo missions were designed over 50 years ago and may be inefficient, outdated, or problematic. The development of new geological tools is an important component of NASA's plans to return to the Moon by 2024 in a program called Artemis. NASA has outlined gaps that must be filled before launching a return to the Moon. One requirement was to explore the development of a harness that could be attached to a spacesuit to carry tools. Relevant recent literature finds few studies that have focused on spacesuit attached tools. This research study addresses a known gap and describes the process of designing, fabricating, and testing a spacesuit-attached multi-purpose Lunar geology sampling tool system to improve astronaut Extravehicular Activity (EVA) efficiency. The research and design method utilized a rapid prototyping process to create a tool system called SAMPLERS. The SAMPLERS prototype consisted of five main components. The details of each component and its design considerations, strengths, and issues are discussed. Hardware testing utilized a mixed method of qualitative and quantitative data collection. Test subjects evaluated the completed SAMPLERS prototype while wearing spacesuits in an analog Lunar environment at the University of North Dakota (UND) Human Spaceflight Laboratory. The objective and subjective data supported the advantages of a spacesuit-attached multi-purpose Lunar sampling tool, such as SAMPLERS. The results show SAMPLERS satisfied requirements and demonstrated it is worthy of consideration as a viable addition to the Artemis geology tool assortment.

NASA's Artemis campaign is making heavy use of simulation to help return humans to the lunar surface by the end of the decade. There are several aspects of the lunar surface and its environment which must be accurately modeled before these simulations can be relied upon to influence decisions being made under these programs. Digital Lunar Exploration Sites, a paper submitted to the 2022 IEEE Aerospace Conference, outlined the process used to generate the lunar surface in a digital environment. This paper will expand upon this topic and delve into the steps being taken by the NASA Exploration Systems Simulations (NExSyS) team at NASA's Johnson Space Center (JSC) to properly verify and validate these simulations, with a focus on the visual aspects of the environment. Natural lighting validation relies in part on the wealth of data generated during the Apollo program. Many images taken by Apollo astronauts on the lunar surface have been replicated in the simulated environments to gain confidence in the accuracy of terrain and lighting models. However, because the environment the Artemis astronauts will experience at the Lunar South Pole (LSP) is dissimilar from the near-equatorial Apollo sites, other validation techniques must be applied. At the LSP, the sun crests only about 1.5 degrees above the horizon and when combined with the lack of a lunar atmosphere, lighting in this region is often very different than what a human would experience on Earth. Solar illumination, earthshine, human eye response, solar blooming, lunar regolith optical properties, and shadows cast by rocks and crater walls will play a significant role in an astronaut's ability to safely conduct an Extra-Vehicular Activity (EVA) or perform a traverse with a lunar rover. Approaches for validation of these aspects of the rendered LSP environment are considered in this paper. In addition to natural lighting, approaches for the validation of artificial lighting models at the LSP are discussed. The JSC Lighting Lab has been studying the illumination profile of the Exploration Informatics Subsystem (xINFO) lighting on the Exploration EVA Mobility Unit (xEMU). How these lights interact with the solar illumination and the shadows being cast on the lunar surface is of particular interest, so the validity of models representing these lights in a human-in-the-loop virtual reality environment becomes very important. This paper also touches on some of the simulation performance considerations when a Human in the Loop (HITL) is present, which drives the need for realtime rendering of the environment. Natural and artificial lighting will play a crucial role to decisions being made when planning and executing missions at the Lunar South Pole (LSP) and it is vitally important to understand the LSP environment before we return.

<p>With growing urbanisation and climate change, flooding is likely to become even more frequent and severe.  Therefore, it is essential to constantly monitor water level changes at a large scale. Synthetic Aperture Radar (SAR) images are often used for flood mapping as they allow a rather straightforward detection of water bodies, at almost all weather and illumination conditions. As the number of satellite observations and global digital elevation models (DEMs) are becoming more available, this mapping approach is gaining in popularity.</p><p>In this study, we propose three different approaches to retrieve water level maps based on the combination of satellite and topographic data, hereby referred to as the global Height Above Nearest Drainage (HAND), the local HAND and the local DEM methods.</p><p>The three approaches are based on the optimization of a threshold applied on the topography (HAND or DEM) data enabling a best fit with the SAR-extracted flood map. The optimized threshold values provide at the same time the normalized water levels (with respect to the drainage network). The water depth map is thus computed from the difference between the water level and the DEM. The global HAND method applies a single optimized threshold to the HAND map, over the entire area of interest. The local HAND method is based on the same concept but optimizes and applies the HAND threshold value locally, using a sliding window. The local DEM thresholding method employs the same principle as the second method but directly on the DEM.</p><p>We evaluate these methods using hydraulic model simulation results and ground truth data, and we carry out several experiments using various SAR images (Envisat, TerraSAR-X and Sentinel-1) and topographic datasets (SRTM, CopDEM and LiDAR).</p><p>The best results are obtained while combining a high-resolution image (e.g:TerraSAR-X) with: 1) a high-resolution dataset (e.g: LiDAR DEM), using the local DEM approach, or 2) a coarse-resolution dataset (e.g: Srtm DEM), using the global HAND approach. RMSDs on the derived water depth maps reach respectively 0.52m and 0.93m.</p>