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At least 19 records

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NASA NTRS2004

Personal Cooling for Extra-Vehicular Activities on Mars

Extra-vehicular activities (EVA) on Mars will require suits with sophisticated thermal control systems so that astronauts can work comfortably for extended periods of time. Any use of consumables such as water that cannot be easily replaced should be of particular concern. In this aspect the EVA suits for Mars environment need to be different from the current Space Shuttle Extra Vehicular Mobility Units (EMU) that depend on water sublimation into space for removing heat from suits. Moreover, Mars environment is quite different from what a typical EMU may be exposed to. These variations call for careful analysis and innovative engineering for design and fabrication of an appropriate thermal control system. This paper presents a thermal analysis of astronaut suits for EVA with medium metabolic intensity under a typical hot and a nominal cold environment on Mars. The paper also describes possible options that would allow conservation of water with low usage of electrical power. The paper then presents the conceptual design of a portable cooling unit for one such solution.

Pu, Zhengxiang↗

NASA NTRS2004

Personal Cooling for Extra-Vehicular Activities on Mars

Pu, Zhengxiang↗

NASA NTRS1987

Automatic antenna switching design for Extra Vehicular Activity (EVA) communication system

An Extra Vehicular Activity (EVA) crewmember had two-way communications with the space station in the Ku-band frequency (12 to 18 GHz). The maximum range of the EVA communications link with the space station is approximately one kilometer for nominal values for transmitter power, antenna gains, and receiver noise figure. The EVA Communications System, that will continue to function regardless of the astronaut's position and orientation, requires an antenna system that has full spherical coverage. Three or more antennas that can be flush mounted on the astronaut's space suit (EMU) and/or his propulsive backpack (MMU), will be needed to provide the desired coverage. As the astronaut moves in the space station, the signal received by a given EVA antenna changes. An automatic antenna switching system is needed that will switch the communication system to the antenna with the largest signal strength. A design for automatic antenna switching is presented and discussed.

Randhawa, Manjit S.↗

NASA NTRS2016

Intra-Extra Vehicular Activity Apollo Spacesuits

Kenneth Thomas will discuss the Apollo Intra-Extra Vehicular Activity (IEVA) spacesuits, which supported launch and reentry and extra-vehicular activity. This program was NASA's first attempt to develop a new suit design from requirements and concepts. Mr. Thomas will chronicle the challenges, developments, struggles, and solutions that culminated in the system that allowed the first human exploration of the Moon and deep space (outside low-Earth orbit). Apollo pressure suit designs allowed the heroic repair of the Skylab space station and supported the first U.S. and Russian spacecraft docking during the Apollo Soyuz Test Project. Mr. Thomas will also discuss the IEVA suits' successes and challenges associated with the IEVA developments of the 1960s.

Thomas, Kenneth S.↗

NASA NTRS2016

Questions and Answers for Ken Thomas' "Intra-Extra Vehicular Activity Russian and Gemini Spacesuits" Presentation

Kenneth Thomas will discuss the Intra‐Extra Vehicular Activity Russian & Gemini spacesuits. While the United States and Russia adapted to existing launch‐ and reentry‐type suits to allow the first human ventures into the vacuum of space, there were differences in execution and capabilities. Mr. Thomas will discuss the advantages and disadvantages of this approach compared to exclusively intravehicular or extra‐vehicular suit systems.

Thomas, Kenneth S.↗

NASA NTRS2016

Intra-Extra Vehicular Activity (IEVA) Russian and Gemini Spacesuits

Kenneth Thomas will discuss the Intra-Extra Vehicular Activity Russian and Gemini spacesuits. While the United States and Russia adapted to existing launch- and reentry-type suits to allow the first human ventures into the vacuum of space, there were differences in execution and capabilities. Mr. Thomas will discuss the advantages and disadvantages of this approach compared to exclusively intra-vehicular or extra-vehicular suit systems.

Thomas, Kenneth S.↗

NASA NTRS1992

Motion-based carriage simulation of extra-vehicular activity (EVA) rescue

A research program was outlined for a series of Extra-Vehicular Activity (EVA) rescue studies. The general purpose is to get a better appreciation of the characteristics describing an EVA rescue scenario. Several studies have been completed in the Virtual Interactive Environment Workstation (VIEW) at NASA Ames Research Center. Similar studies are planned for a variety of simulators both to get more reliable results for the EVA rescue problem and to baseline the simulators against one another. Work is planned for a motion-based carriage to expand the validity of the previously obtained results.

Brody, Adam R.↗

NASA NTRS2011

On the Modeling of Electrical Effects Experienced by Space Explorers During Extra Vehicular Activities: Intracorporal Currents, Resistances, and Electric Fields

Recent research has shown that space explorers engaged in Extra Vehicular Activities (EVAs) may be exposed, under certain conditions, to undesired electrical currents. This work focuses on determining whether these undesired induced electrical currents could be responsible for involuntary neuromuscular activity in the subjects, possibly caused by either large diameter peripheral nerve activation or reflex activity from cutaneous afferent stimulation. An efficient multiresolution variant of the admittance method along with a millimeter-resolution model of a male human body were used to calculate induced electric fields, resistance between contact electrodes used to simulate the potential exposure condition, and currents induced in the human body model. Results show that, under realistic exposure conditions using a 15V source, current density magnitudes and total current injected are well above previously reported startle reaction thresholds. This indicates that, under the considered conditions, the subjects could experience involuntary motor response.

Cela, Carlos J.↗

NASA NTRS2016

Experiences with Extra-Vehicular Activities in Response to Critical ISS Contingencies

The maturation of the International Space Station (ISS) design from the proposed Space Station Freedom to today's current implementation resulted in external hardware redundancy vulnerabilities in the final design. Failure to compensate for or respond to these vulnerabilities could put the ISS in a posture where it could no longer function as a habitable space station. In the first years of ISS assembly, these responses were to largely be addressed by the continued resupply and Extra-Vehicular Activity (EVA) capabilities of the Space Shuttle. Even prior to the decision to retire the Space Shuttle, it was realized that ISS needed to have its own capability to be able to rapidly repair or replace external hardware without needing to wait for the next cargo resupply mission. As documented in a previous publication, in 2006 development was started to baseline Extra-Vehicular Activity (EVA, or spacewalk) procedures to replace hardware components whose failure would expose some of the ISS vulnerabilities should a second failure occur. This development work laid the groundwork for the onboard crews and the ground operations and engineering teams to be ready to replace any of this failed hardware. In 2010, this development work was put to the test when one of these pieces of hardware failed. This paper will provide a brief summary of the planning and processes established in the original Contingency EVA development phase. It will then review how those plans and processes were implemented in 2010, highlighting what went well as well as where there were deficiencies between theory and reality. This paper will show that the original approach and analyses, though sound, were not as thorough as they should have been in the realm of planning for next worse failures, for documenting Programmatic approval of key assumptions, and not pursuing sufficient engineering analysis prior to the failure of the hardware. The paper will further highlight the changes made to the Contingency EVA preparation team structure, approach, goals, and the resources allocated to its work after the 2010 events. Finally, the authors will overview the implementation of these updates in addressing failures onboard the ISS in 2012, 2013, and 2014. The successful use of the updated approaches, and the application of the approaches to other spacewalks, will demonstrate the effectiveness of this additional work and make a case for putting significant time and resources into pre-failure planning and analysis for critical hardware items on human-tended spacecraft.

Van Cise, E. A.↗

NASA NTRS2016

Experiences with Extra-Vehicular Activities in Response to Critical ISS Contingencies

The maturation of the International Space Station (ISS) design from the proposed Space Station Freedom to today's current implementation resulted in external hardware redundancy vulnerabilities in the final design. Failure to compensate for or respond to these vulnerabilities could put the ISS in a posture to where it could no longer function as a habitable space station. In the first years of ISS assembly, these responses were to largely be addressed by the continued resupply and Extra-Vehicular Activity (EVA) capabilities of the Space Shuttle. Even prior to the decision to retire the Space Shuttle, it was realized that ISS needed to have its own capability to be able to rapidly repair or replace external hardware without needing to wait for the next cargo resupply mission. As documented in a previous publicatoin5, in 2006 development was started to baseline Extra- Vehicular Activity (EVA, or spacewalk) procedures to replace hardware components whose failure would expose some of the ISS vulnerabilities should a second failure occur. This development work laid the groundwork for the onboard crews and the ground operations and engineering teams to be ready to replace any of this failed hardware. In 2010, this development work was put to the test when one of these pieces of hardware failed. This paper will provide a brief summary of the planning and processes established in the original Contingency EVA development phase. It will then review how those plans and processes were implemented in 2010, highlighting what went well as well as where there were deficiencies between theory and reality. This paper will show that the original approach and analyses, though sound, were not as thorough as they should have been in the realm of planning for next worse failures, for documenting Programmatic approval of key assumptions, and not pursuing sufficient engineering analysis prior to the failure of the hardware. The paper will further highlight the changes made to the Contingency EVA preparation team structure, approach, goals, and the resources allocated to its work after the 2010 events. Finally, the authors will overview the implementation of these updates in addressing failures onboard the ISS in 2012, 2013, and 2014. The successful use of the updated approaches, and the application of the approaches to other spacewalks, will demonstrate the effectiveness of this additional work and make a case for putting significant time and resources into pre-failure planning and analysis for critical hardware items on human-tended spacecraft.

Van Cise, E. A.↗

NASA NTRS2009

802.16e System Profile for NASA Extra-Vehicular Activities

This report identifies an 802.16e system profile that is applicable to a lunar surface wireless network, and specifically for meeting extra-vehicular activity (EVA) data flow requirements. EVA suit communication needs are addressed. Design-driving operational scenarios are considered. These scenarios are then used to identify a configuration of the 802.16e system (system profile) that meets EVA requirements, but also aim to make the radio realizable within EVA constraints. Limitations of this system configuration are highlighted. An overview and development status is presented by Toyon Research Corporation concerning the development of an 802.16e compatible modem under NASA s Small Business Innovative Research (SBIR) Program. This modem is based on the recommended system profile developed as part of this report. Last, a path forward is outlined that presents an evolvable solution for the EVA radio system and lunar surface radio networks. This solution is based on a custom link layer, and 802.16e compliant physical layer compliant to the identified system profile, and a later progression to a fully interoperable 802.16e system.

Foore, Lawrence R.↗

NASA NTRS1999

Wireless Video System for Extra Vehicular Activity in the International Space Station and Space Shuttle Orbiter Environment

The Wireless Video System (WVS) provides real-time video coverage of astronaut extra vehicular activities during International Space Station (ISS) assembly. The ISS wireless environment is unique due to the nature of the ISS structure and multiple RF interference sources. This paper describes how the system was developed to combat multipath, blockage, and interference using an automatic antenna switching system. Critical to system performance is the selection of receiver antenna installation locations determined using Uniform Geometrical Theory of Diffraction (GTD) techniques.

Loh, Yin C.↗

NASA NTRS2018

NASA's Advanced Extra-Vehicular Activity Space Suit Pressure Garment 2018 Status and Development Plan

This paper presents both near-term and long-term NASA Advanced Extra-vehicular Activity (EVA) Pressure Garment development efforts. The near-term plan discusses the development of pressure garment components for the first design iteration of the International Space Station exploration space suit demonstration configuration, termed the xEMU Demo. The xEMU Demo effort is targeting a 2023-2025 flight demonstration timeframe. The Fiscal Year 2018 (FY18) tasks focus on either the initiation or maturation of component design, depending on the state of development of the components, and the assembly of a suit configuration, termed Z-2.5, that will be used to evaluate changes to the upper torso geometry in a Neutral Buoyancy Laboratory (NBL) test series. The geometry changes, which are being driven by the need to reduce the front-to-back dimension of the advanced extravehicular mobility unit, diverge from a proven shape, such as that of the Mark III Space Suit Technology Demonstrator. The 2018 efforts culminate in the Z-2.5 NBL test. The lessons learned from the Z-2.5 NBL test will inform the xEMU Demo design as the effort moves toward design verification testing and preliminary and critical design reviews. The long-term development plan looks to surface exploration and operations. Technology and knowledge gaps exist between the xEMU Demo configuration; a lunar surface capability, xEMU; and Mars surface suit, mEMU. The development plan takes into account both the priority and the anticipated development duration for each particular technology. The long-term development plan will be updated as risks are mitigated and gaps are closed, but its overarching structure will remain intact.

space suit↗

NASA NTRS2018

Simplified Aid for Extra-Vehicular Activity Rescue (SAFER) Battery Assessment

In 2013, the Boeing Company model 787-8 Dreamliner commercial aircraft experienced three catastrophic lithium (Li) battery failures. The cause of each failure resulted in a single-cell thermal runaway (TR) condition, which propagated to adjacent battery cells. Two of the failures involved rechargeable lithium-ion (Li-Ion) batteries, and the third event involved a nonrechargeable lithium-manganese dioxide (Li-MnO2) battery. In response to these Li battery failures, the NASA Engineering and Safety Center (NESC) approved a technical assessment of the International Space Station Simplified Aid for Extra-Vehicular Activity Rescue (SAFER) Li non-rechargeable battery. This assessment was conducted to evaluate the SAFER Li nonrechargeable battery safety design features against Boeing 787 Dreamliner Li battery failure lessons learned. Specifically, this investigation focused on assessing the severity of a SAFER battery TR hazard conditions.

Iannello, Christopher J.↗

NASA NTRS1987

Design, development and evaluation of Stanford/Ames Extra-Vehicular Activity (EVA) prehensors

A summary is given of progress to date on work proposed in 1983 and continued in 1985, including design iterations on three different types of manually powered prehensors, construction of functional mockups of each and culminating in detailed drawings and specifications for suit-compatible sealed units for testing under realistic conditions.

Leifer, Larry J.↗

NASA NTRS1991

Simulation of extra-vehicular activity (EVA) self-rescue

Self-rescue during EVA is examined in terms of the use of a hand-held thruster that is similar to the hand-held maneuvering units HHMU developed for earlier programs. The problem of assessing velocity-increment requirements is addressed by means of examples of simulation technologies for studying EVA. The technologies evaluated include virtual reality systems such as the Virtual Interactive Environment Workstation (VIEW) and the Space Operations Simulator, and standard approaches like the air-bearing floor and the space shuttle. The VIEW is employed for a study of five trained NASA subjects that conduct a simulated return to a spacecraft with an HMMU under variable conditions. The study demonstrates the efficacy of VIEW for obtaining fuel-consumption values, and separation velocity is identified as the most significant determinant of the fuel and time requirements for a self-rescue operation.

Brody, Adam R.↗

NASA NTRS1992

Investigation of the effects of Extra Vehicular Activity (EVA) and Launch and Entry (LES) gloves on performance

Human capabilities such as dexterity, manipulability, and tactile perception are unique and render the hand as a very versatile, effective and a multipurpose tool. This is especially true for unknown environments such as the EVA environment. In the microgravity environment interfaces, procedures, and activities are too complex, diverse, and defy advance definition. Under these conditions the hand becomes the primary means of locomotion, restraint, and material handling. Facilitation of these activities, with simultaneous protection from the cruel EVA environment are the two, often conflicting, objectives of glove design. The objectives of this study was (1) to assess the effects of EVA gloves at different pressures on human hand capabilities, (2) to devise a protocol for evaluating EVA gloves, (3) to develop force time relations for a number of EVA glove pressure combinations, and (4) to evaluate two types of launch and entry suit gloves. The objectives were achieved through three experiments. The experiments for achieving objectives 1, 2, and 3 were performed in the glove box in building 34. In experiment 1 three types of EVA gloves were tested at five pressure differentials. A number of performance measures were recorded. In experiment 2 the same gloves as in experiment 1 were evaluated in a reduced number of pressure conditions. The performance measure was endurance time. Six subjects participated in both the experiments. In experiment 3 two types of launch and entry suit gloves were evaluated using a paradigm similar to experiment 1. Currently the data is being analyzed. However for this report some summary analyses have been performed. The results indicate that a) With EVA gloves strength is reduced by nearly 50 percent, b) performance decrements increase with increasing pressure differential, c) TMG effects are not consistent across the three gloves tested, d) some interesting gender glove interactions were observed, some of which may have been due to the extent (or lack of) fit of the glove to the hand, and e) differences in performance exist between partial pressure suit glove and full pressure suit glove, especially in the unpressurized condition.

Bishu, Ram R.↗

NASA NTRS1994

Extra-Vehicular Activity (EVA) glove evaluation test protocol

One of the most critical components of a space suit is the gloves, yet gloves have traditionally presented significant design challenges. With continued efforts at glove development, a method for evaluating glove performance is needed. This paper presents a pressure-glove evaluation protocol. A description of this evaluation protocol, and its development is provided. The protocol allows comparison of one glove design to another, or any one design to bare-handed performance. Gloves for higher pressure suits may be evaluated at current and future design pressures to drive out differences in performance due to pressure effects. Using this protocol, gloves may be evaluated during design to drive out design problems and determine areas for improvement, or fully mature designs may be evaluated with respect to mission requirements. Several different test configurations are presented to handle these cases. This protocol was run on a prototype glove. The prototype was evaluated at two operating pressures and in the unpressurized state, with results compared to bare-handed performance. Results and analysis from this test series are provided, as is a description of the configuration used for this test.

Hinman-Sweeney, E. M.↗