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At least 163 records · Page 9

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NASA NTRS2024

Surface EVA Architectural Drivers

Key elements of NASA’s Moon to Mars Objectives for expanding humanity’s presence beyond low-Earth orbit will require surface-based, partial-gravity extravehicular activities (EVAs). Surface EVA needs affect many aspects of the exploration architecture, including EVA suit subsystems, such as suit or pressure garment mobility, the portable life support system, and the informatics system; and external systems, such as habitation modules and surface mobility platforms.

Moon↗

NASA NTRS1972

Lunar surface EVA photography of Hadley Rille: Contrast as a constraint

Prior to the Apollo 15 flight, preliminary plans for lunar surface EVA photography of Hadley Rille were examined from the standpoint of expected photographic contrast. Considerable variation in contrast was predicted, resulting in suggestions for specific targets either to be emphasized or ignored at various EVA photo stations. Apollo 15 surface EVA photography appears to have highly satisfactory contrast, generally confirming the predictions. The general technique can be applied to Apollo 16 and 17 photography.

Radin, H. W.↗

NASA NTRS1973

Teleoperators and EVA for Shuttle missions

Review of the methods currently being contemplated for enabling the Space Shuttle to perform the Shuttle and payload support missions. Two general approaches to carrying out such activity are discussed - namely, the use of teleoperators and astronaut extravehicular activity (EVA). Detailed descriptions are given of an attached manipulator system (AMS) and a free-flying teleoperator (FFTO), noting the applications, capabilities, and limitations of each. The primary technology development areas for the AMS are in the areas of stabilization, structure, and manual control, while the technology areas of primary concern in the case of the FFTO include the manipulator-grappler system, the control system, the video system, and the mobility system. Four modes of EVA that are possible for the Shuttle are cited, noting the unlikelihood of direct applicability of EVA to payload deployment and retrieval and its feasibility for payload servicing and experiment support.

Malone, T. B.↗

NASA NTRS1979

Simulated EVA operation of a remote connector assembly test report

The features of a connector concept with respect to timelines and ease of connection by EVA (extravehicular activity), in various mating orientations were evaluated. The connector tests were conducted by thee EVA astronaut test subjects. Each of four test conditions (baseline, off angle, overhead, and with visual obstruction) were run three times by each of the test subjects. Time data were taken on each test run. Visual and voice communications with the subjects were recorded. The tests demonstrated that EVA personnel can perform connection tasks in relatively short times (generally one minute) and the connector configuration was a reasonable design base for such tasks. The in-situ communications and post-test comments indicated that the connector was generally acceptable but requires improvement to its manual interface features.

Lefever, A.↗

NASA NTRS1980

EVA manipulation and assembly of space structure columns

Assembly techniques and hardware configurations used in assembly of the basic tetrahedral cell by A7LB pressure-suited subjects in a neutral bouyancy simulator were studied. Eleven subjects participated in assembly procedures which investigated two types of structural members and two configurations of attachment hardware. The assembly was accomplished through extra-vehicular activity (EVA) only, EVA with simulated manned maneuvering unit (MMU), and EVA with simulated MMU and simulated remote manipulator system (RMS). Assembly times as low as 10.20 minutes per tetrahedron were achieved. Task element data, as well as assembly procedures, are included.

Loughead, T. E.↗

NASA NTRS1986

Advanced EVA system design requirements study

Design requirements and criteria for the Space Station Advanced Extravehicular Activity System (EVAS) including crew enclosures, portable life support systems, maneuvering propulsion systems, and related extravehicular activity (EVA) support equipment were defined and established. The EVA mission requirements, environments, and medical and physiological requirements, as well as opertional, procedures, and training issues were considered.

Source record↗

NASA NTRS1986

Advanced EVA system design requirements study, executive summary

Design requirements and criteria for the space station advanced Extravehicular Activity System (EVAS) including crew enclosures, portable life support systems, maneuvering propulsion systems, and related EVA support equipment were established. The EVA mission requirements, environments, and medical and physiological requirements, as well as operational, procedures and training issues were considered.

Source record↗

NASA NTRS1987

Effect of STS space suit on astronaut dominant upper limb EVA work performance

The STS Space Suited and unsuited dominant upper limb performance was evaluated in order to quantify future EVA astronaut skeletal muscle upper limb performance expectations. Testing was performed with subjects standing in EVA STS foot restraints. Data was collected with a CYBEX Dynamometer enclosed in a waterproof container. Control data was taken in one g. During one g testing, weight of the Space Suit was relieved from the subject via an overhead crane with a special connection to the PLSS of the suit. Experimental data was acquired during simulated zero g, accomplished by neutral buoyancy in the Weightless Environment Training Facility. Unsuited subjects became neutrally buoyant via SCUBA BC vests. Actual zero g experimental data was collected during parabolic arc flights on board NASA's modified KC-135 aircraft. During all test conditions, subjects performed five EVA work tasks requiring dominant upper limb performance and ten individual joint articulation movements. Dynamometer velocities for each tested movement were 0 deg/sec, 30 or 60 deg/sec and 120 or 180 deg/sec, depending on the test, with three repetitions per test. Performance was measured in foot pounds of torque.

Greenisen, Michael C.↗

NASA NTRS1987

Dynamics, control and sensor issues pertinent to robotic hands for the EVA retriever system

Basic dynamics, sensor, control, and related artificial intelligence issues pertinent to smart robotic hands for the Extra Vehicular Activity (EVA) Retriever system are summarized and discussed. These smart hands are to be used as end effectors on arms attached to manned maneuvering units (MMU). The Retriever robotic systems comprised of MMU, arm and smart hands, are being developed to aid crewmen in the performance of routine EVA tasks including tool and object retrieval. The ultimate goal is to enhance the effectiveness of EVA crewmen.

Mclauchlan, Robert A.↗

NASA NTRS1988

The development of a test methodology for the evaluation of EVA gloves

This paper describes the development of a standardized set of tests designed to assess EVA-gloved hand capabilities in six measurement domains: range of motion, strength, tactile perception, dexterity, fatigue, and comfort. Based upon an assessment of general human-hand functioning and EVA task requirements, several tests within each measurement domain were developed to provide a comprehensive evaluation. All tests were designed to be conducted in a glove box with the bare hand as a baseline and the EVA glove at operating pressure.

O'Hara, John M.↗

NASA NTRS1989

EVA space construction - Experience and fundamental issues

Results are presented from EVA space construction studies performed in 1 g, simulated 0 g, and on-orbit. The studies include tests of astronaut participation on the Mobile Work Station concept and the Swing-Arm Beam Erector. Also, results from the Experimental Assembly of Structures in EVA and the Assembly Concept for Construction of Erectable Space Structure programs are summarized. EVA construction applications for the Space Station are discussed and construction scenarios are developed.

Heard, Walter L., Jr.↗

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 NTRS1991

A prototype power assist EVA glove

The most recent generation of space suit EVA gloves has addressed the problem of loose fit and stiffness in the fingers, but it remains difficult to build a glove assembly with low metacarpophalangeal joint stiffness. Fatigue due to constantly displacing the glove from a neutral position has been reported as the limiting factor in some EVA activities. This paper outlines an actuation system that uses gas filled bladders attached to the back of the EVA glove to provide the necessary force to bend the glove at the metacarpal joint, thus providing greater endurance during finger grasping tasks. A simple on-off controller senses hand movement through small pressure sensors between the finger and the glove restraint. The controller then fills or exhausts the bladders on the back of the glove to effectively move the neutral position of the glove as the hand inside moves.

Main, John A.↗

NASA NTRS1990

Evolving EVA system capability for the evolving Space Station Freedom requirements

Viewgraphs on evolving extravehicular activity (EVA) system capability for the evolving Space Station Freedom requirements are presented. Topics covered include: pre-scrub 1989 baseline; approach shift resulting from scrub 1989; considerations for alternative selection; EVA supply options; and key technologies for evolution of EVA system life support.

Slade, Howard↗

NASA NTRS1992

Power assist EVA glove development

The design of the EVA glove is examined, emphasizing the development of a more flexible metacarpophalangeal (MCP) joint for the EVA glove. The analysis of the EVA glove MCP joint is reviewed and the glove design process is recapitulated. Experimental tests of the glove are summarized.

Main, John A.↗

NASA NTRS1992

Spaceborne construction and operations planning - Decision rules for selecting EVA, telerobot, and combined work-systems

An approach is presented for selecting an appropriate work-system for performing construction and operations tasks by humans and telerobots. The decision to use extravehicular activity (EVA) performed by astronauts, extravehicular robotics (EVR), or a combination of EVA and EVR is determined by the ratio of the marginal costs of EVA, EVR, and IVA. The approach proposed here is useful for examining cost trade-offs between tasks and performing trade studies of task improvement techniques (human or telerobotic).

Smith, Jeffrey H.↗

NASA NTRS1993

Investigation of the effects of extravehicular activity (EVA) gloves on performance

The objective was to assess the effects of extravehicular activity (EVA) gloves at different pressures on human hand capabilities. A factorial experiment was performed in which three types of EVA gloves were tested at five pressure differentials. The independent variables tested in this experiment were gender, glove type, pressure differential, and glove make. Six subjects participated in an experiment where a number of dexterity measures, namely time to tie a rope, and the time to assemble a nut and bolt were recorded. Tactility was measured through a two point discrimination test. The results indicate that with EVA gloves strength is reduced by nearly 50 percent, there is a considerable reduction in dexterity, performance decrements increase with increasing pressure differential, and 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. The implications for the designer are discussed.

Bishu, Ram R.↗

NASA NTRS1993

Design and simulation of EVA tools for first servicing mission of HST

The Hubble Space Telescope (HST) was launched into near-earth orbit by the space shuttle Discovery on April 24, 1990. The payload of two cameras, two spectrographs, and a high-speed photometer is supplemented by three fine-guidance sensors that can be used for astronomy as well as for star tracking. A widely reported spherical aberration in the primary mirror causes HST to produce images of much lower quality than intended. A space shuttle repair mission in late 1993 will install small corrective mirrors that will restore the full intended optical capability of the HST. The first servicing mission (FSM) will involve considerable extravehicular activity (EVA). It is proposed to design special EVA tools for the FSM. This report includes details of the data acquisition system being developed to test the performance of the various EVA tools in ambient as well as simulated space environment.

Naik, Dipak↗