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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 1,207 records · Page 67

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NASA NTRS1987

Effects of prolonged weightlessness on self-motion perception and eye movements evoked by roll and pitch

Seven astronauts reported translational self-motion during roll simulation 1-3 h after landing following 5-7 d of orbital flight. Two reported strong translational self-motion perception when they performed pitch head motions during entry and while the orbiter was stationary on the runway. One of two astronauts from whom adequate data were collected exhibited a 132-deg shift in the phase angle between roll stimulation and horizontal eye position 2 h after landing. Neither of two from whom adequate data were collected exhibited increased horizontal eye movement amplitude or disturbance of voluntary pitch or roll body motion immediately postflight. These results are generally consistent with an otolith tilt-translation reinterpretation model and are being applied to the development of apparatus and procedures intended to preadapt astronauts to the sensory rearrangement of weightlessness.

Reschke, Millard F.↗

NASA NTRS1988

Results of EVA/mobile transporter space station truss assembly tests

Underwater neutral buoyance tests were conducted to evaluate the use of a Mobile Transporter concept in conjunction with EVA astronauts to construct the Space Station Freedom truss structure. A three-bay orthogonal tetrahedral truss configuration with a 15 foot square cross section was repeatedly assembled by a single pair of pressure suited test subjects working from the Mobile Transporter astronaut positioning devices (mobile foot restraints). The average unit assembly time (which included integrated installation of utility trays) was 27.6 s/strut, or 6 min/bay. The results of these tests indicate that EVA assembly of space station size structures can be significantly enhanced when using a Mobile Transporter equipped with astronaut positioning devices. Rapid assembly time can be expected and are dependent primarily on the rate of translation permissible for on-orbit operations. The concept used to demonstate integrated installation of utility trays requires minimal EVA handling and consequentially, as the results show, has little impact on overall assembly time.

Watson, Judith J.↗

NASA NTRS1989

Payloads simulation in the Shuttle Mission Training Facility

The Shuttle Mission Training Facility (SMFT) at the NASA Johnson Space Center is the primary facility for full mission training of astronauts. The training provided in the SMTF includes payload operations that are performed by the astronauts while the Space Shuttle is in orbit. This training requires real-time simulation of the operational aspects of Shuttle payloads as well as simulation of the interaction between payloads and the Orbiter. For this purpose the SMTF contains Payloads Simulators (PLS) that are coupled to and operated in synchronization with the Shuttle Vehicle Simulators. The PLS are used for simulating all payloads with the exception of the European Space Agency's Spacelab. The SMTF contains a separate Spacelab Simulator for training Spacelab astronauts. This paper provides a synopsis of actual payload operations, the methodology for payload simulation in the SMTF, and the system architecture of the PLS.

Hajare, Ankur R.↗

NASA NTRS1990

Stanford/NASA-Ames Center of Excellence in model-based human performance

The human operator plays a critical role in many aeronautic and astronautic missions. The Stanford/NASA-Ames Center of Excellence in Model-Based Human Performance (COE) was initiated in 1985 to further our understanding of the performance capabilities and performance limits of the human component of aeronautic and astronautic projects. Support from the COE is devoted to those areas of experimental and theoretical work designed to summarize and explain human performance by developing computable performance models. The ultimate goal is to make these computable models available to other scientists for use in design and evaluation of aeronautic and astronautic instrumentation. Within vision science, two topics have received particular attention. First, researchers did extensive work analyzing the human ability to recognize object color relatively independent of the spectral power distribution of the ambient lighting (color constancy). The COE has supported a number of research papers in this area, as well as the development of a substantial data base of surface reflectance functions, ambient illumination functions, and an associated software package for rendering and analyzing image data with respect to these spectral functions. Second, the COE supported new empirical studies on the problem of selecting colors for visual display equipment to enhance human performance in discrimination and recognition tasks.

Wandell, Brian A.↗

NASA NTRS1990

Project Exodus

A design for a manned Mars mission, PROJECT EXODUS is presented. PROJECT EXODUS incorporates the design of a hypersonic waverider, cargo ship and NIMF (nuclear rocket using indigenous Martian fuel) shuttle lander to safely carry out a three to five month mission on the surface of Mars. The cargo ship transports return fuel, return engine, surface life support, NIMF shuttle, and the Mars base to low Mars orbit (LMO). The cargo ship is powered by a nuclear electric propulsion (NEP) system which allows the cargo ship to execute a spiral trajectory to Mars. The waverider transports ten astronauts to Mars and back. It is launched from the Space Station with propulsion provided by a chemical engine and a delta velocity of 9 km/sec. The waverider performs an aero-gravity assist maneuver through the atmosphere of Venus to obtain a deflection angle and increase in delta velocity. Once the waverider and cargo ship have docked the astronauts will detach the landing cargo capsules and nuclear electric power plant and remotely pilot them to the surface. They will then descend to the surface aboard the NIMF shuttle. A dome base will be quickly constructed on the surface and the astronauts will conduct an exploratory mission for three to five months. They will return to Earth and dock with the Space Station using the waverider.

Bryant, Rodney↗

NASA NTRS1989

Emergency egress fixed rocket package

A method of effecting the in-flight departure of an astronaut from a shuttle craft, and apparatus is presented. A plurality of removeable compartment covers are provided, behind which rocket assemblies are stowed. To actuate the system, the astronaut pulls off a tab from one of the compartments which exposes a cannister having a lanyard with a hook. The lanyard extends around a spring biased sleeve with a safety lever preventing rocket ignition until the hook is moved by the astronaut. Upward movement of the hook allows the trigger mechanism to actuate the system resulting in the rods projecting out of the hatch. When the lanyard becomes taut, a lanyard elongation detector transmits a signal to the firing mechanisms to fire the rocket.

Allen, Margaret A.↗

NASA NTRS1991

Conceptual studies on the integration of a nuclear reactor system to a manned rover for Mars missions

Multiyear civilian manned missions to explore the surface of Mars are thought by NASA to be possible early in the next century. Expeditions to Mars, as well as permanent bases, are envisioned to require enhanced piloted vehicles to conduct science and exploration activities. Piloted rovers, with 30 kWe user net power (for drilling, sampling and sample analysis, onboard computer and computer instrumentation, vehicle thermal management, and astronaut life support systems) in addition to mobility are being considered. The rover design, for this study, included a four car train type vehicle complete with a hybrid solar photovoltaic/regenerative fuel cell auxiliary power system (APS). This system was designed to power the primary control vehicle. The APS supplies life support power for four astronauts and a limited degree of mobility allowing the primary control vehicle to limp back to either a permanent base or an accent vehicle. The results showed that the APS described above, with a mass of 667 kg, was sufficient to provide live support power and a top speed of five km/h for 6 hours per day. It was also seen that the factors that had the largest effect on the APS mass were the life support power, the number of astronauts, and the PV cell efficiency. The topics covered include: (1) power system options; (2) rover layout and design; (3) parametric analysis of total mass and power requirements for a manned Mars rover; (4) radiation shield design; and (5) energy conversion systems.

El-Genk, Mohamed S.↗

NASA NTRS1991

A method of evaluating efficiency during space-suited work in a neutral buoyancy environment

The purpose was to investigate efficiency as related to the work transmission and the metabolic cost of various extravehicular activity (EVA) tasks during simulated microgravity (whole body water immersion) using three space suits. Two new prototype space station suits, AX-5 and MKIII, are pressurized at 57.2 kPa and were tested concurrently with the operationally used 29.6 kPa shuttle suit. Four male astronauts were asked to perform a fatigue trial on four upper extremity exercises during which metabolic rate and work output were measured and efficiency was calculated in each suit. The activities were selected to simulate actual EVA tasks. The test article was an underwater dynamometry system to which the astronauts were secured by foot restraints. All metabolic data was acquired, calculated, and stored using a computerized indirect calorimetry system connected to the suit ventilation/gas supply control console. During the efficiency testing, steady state metabolic rate could be evaluated as well as work transmitted to the dynamometer. Mechanical efficiency could then be calculated for each astronaut in each suit performing each movement.

Greenisen, Michael C.↗

NASA NTRS1991

NASA/USRA advanced design program activity 1990/1991

Four problems were defined which had aspects which would be reasonably assigned to an interdisciplinary design team. The design problems are: (1) design of a thermal shield for a lunar telescope (thermal protection for a lunar telescope); (2) selenotextile shielding structure (a structure to protect a lunar habitat from intense solar radiation of tubes of woven polytetrafluoroethylene coated fiberglass fabric); (3) pneumatically assisted elbow joint design for the NASA Zero-prebreathe suit (will allow astronauts to make the transition from a high pressure internal environment to a lower pressure suit without spending time in an air lock); and (4) electrochemical system to power assist an astronaut's finger joints (assist in the movement of an astronaut's distal and proximal interphalangeal finger joints).

Dorrity, J. Lewis↗

NASA NTRS1992

An evaluation of training effectiveness of an intelligent tutoring system

The study evaluated the training effectiveness of an intelligent tutoring system (ITS) for the Remote Manipulator System (RMS). The study examined how well individuals learn the training content and skills from the RMS ITS and to what extent the content and skills learned using the ITS transfer to RMS task performance in the SES, a high fidelity simulator. Three astronauts completed 8 2-hour ITS sessions addressing movement in three coordinate systems, grapple, ungrapple, berth, and unberth procedures, and singularities and reach limits. Their performance was also observed in an SES training session. Performance data were collected using multiple measures: ITS task performance, transfer performance on the SES, a conceptual knowledge test, an opinion survey completed by astronauts, and comments and observations from astronauts and trainers. Results indicated the RMS ITS to be moderately effective and provided evidence of the efficacy of ITS's, in general. Comments and suggestions are provided relating to how the ITS could be improved and to enable decision makers to judge the effectiveness of the RMS ITS.

Johnson, Debra Steele↗

NASA NTRS1992

Evaluation of tests for vestibular function

Vestibular testing methodologies are examined in terms of their clinical value and applicability to the assessment of astronaut candidates and human responses to microgravity. Classical and novel testing approaches are examined in terms of nine functions such as otolith organs, vestibular neural processing, and ocular motor systems. The tests reviewed include the basic vestibular-function test battery, postural stability testing, visual-vestibular interaction, reactions to off-axis rotation, and vestibular evoked responses. The basic test battery is shown to be essential for astronaut and inertial-environment baseline-data evaluations, whereas the newer and research tests are only recommended in special cases. Stimulus rearrangement and motion-sickness tests are indicated for testing adaptation to inertial environments. Postural stability and visual-vestibular interaction are recommended for evaluating one's suitability for being an astronaut.

Source record↗

NASA NTRS1992

Requirements and applications for robotic servicing of military space systems

The utility of on-orbit servicing of spacecraft has been demonstrated by NASA several times using shuttle-based astronaut EVA. There has been interest in utilizing on-orbit servicing for military space systems as well. This interest has been driven by the increasing reliance of all branches of the military upon space-based assets, the growing numbers, complexity, and cost of those assets, and a desire to normalize support policies for space-based operations. Many military satellites are placed in orbits which are unduly hostile for astronaut operations and/or cannot be reached by the shuttle. In addition, some of the projected tasks may involve hazardous operations. This has led to a focus on robotic systems, instead of astronauts, for the basis of projected servicing systems. This paper describes studies and activities which will hopefully lead to on-orbit servicing being one of the tools available to military space systems designers and operators. The utility of various forms of servicing has been evaluated for present and projected systems, critical technologies have been identified, and strategies for the development and insertion of this technology into operational systems have been developed. Many of the projected plans have been adversely affected by budgetary restrictions and evolving architectures, but the fundamental benefits and requirements are well understood. A method of introducing servicing capabilities in a manner which has a low impact on the system designer and does not require the prior development of an expensive infrastructure is discussed. This can potentially lead to an evolutionary implementation of the full technology.

Ledford, Otto C., Jr.↗

NASA NTRS1992

Space life sciences perspectives for Space Station Freedom

It is now generally acknowledged that the life science discipline will be the primary beneficiary of Space Station Freedom. The unique facility will permit advances in understanding the consequences of long duration exposure to weightlessness and evaluation of the effectiveness of countermeasures. It will also provide an unprecedented opportunity for basic gravitational biology, on plants and animals as well as human subjects. The major advantages of SSF are the long duration exposure and the availability of sufficient crew to serve as subjects and operators. In order to fully benefit from the SSF, life sciences will need both sufficient crew time and communication abilities. Unlike many physical science experiments, the life science investigations are largely exploratory, and frequently bring unexpected results and opportunities for study of newly discovered phenomena. They are typically crew-time intensive, and require a high degree of specialized training to be able to react in real time to various unexpected problems or potentially exciting findings. Because of the long duration tours and the large number of experiments, it will be more difficult than with Spacelab to maintain astronaut proficiency on all experiments. This places more of a burden on adequate communication and data links to the ground, and suggests the use of AI expert system technology to assist in astronaut management of the experiment. Typical life science experiments, including those flown on Spacelab Life Sciences 1, will be described from the point of view of the demands on the astronaut. A new expert system, 'PI in a Box,' will be introduced for SLS-2, and its applicability to other SSF experiments discussed. (This paper consists on an abstract and ten viewgraphs.)

Young, Laurence R.↗

NASA NTRS1992

Utilization of the graded universal testing system to increase the efficiency for assessing aerobic and anaerobic capacity

The in-flight exercise test performed by cosmonauts as part of the Russian Exercise Countermeasure Program is limited to 5 minutes due to communication restrictions. During a recent graded exercise test on a U.S. Shuttle flight, the test was terminated early due to an upcoming loss of signal (LOS) with the ground. This exercise test was a traditional test where the subject's exercise capacity dictates the length of the test. For example, one crew member may take 15 minutes to complete the test, while another may take 18 minutes. The traditional exercise test limits the flight schedulers to large blocks of space flight time in order to provide medical and research personnel information on the fitness capacity (maximal oxygen uptake: VO2max) of crew members during flight. A graded exercise test that would take a finite amount of time and a set preparation and recovery time would ease this problem by allowing flight schedulers to plan exercise tests in advance of LOS. The Graded Universal Testing System (GUTS) was designed to meet this goal. Fitness testing of astronauts before and after flight provides pertinent data on many variables. The Detailed Supplemental Objective (DSO608) protocol (6) is one of the graded exercise tests (GXT) currently used in astronaut testing before and after flight. Test times for this protocol have lasted from 11 to 18 minutes. Anaerobic capacity is an important variable that is currently not being evaluated before and after flight. Recent reports (1,2,5) from the literature have suggested that the oxygen deficit at supramaximal exercise is a measure of anaerobic capacity. We postulated that the oxygen deficit at maximal exercise would be an indication of anaerobic capacity. If this postulate can be accepted, then the efficiency of acquiring data from a graded exercise test would increase at least twofold. To examine this hypothesis anaerobic capacity was measured using a modified treadmill test (3,4) designed to exhaust the anaerobic systems in approximately 45 to 75 seconds. Lactate concentration in the blood was analyzed after all tests, since lactate is the end-product of anaerobic energy production. Therefore, the peak lactate response is an additional indication of anaerobic capacity. A preliminary comparison of the GUTS and the DSO608 suggests that the GUTS protocol would increase the efficiency of VO2max testing of astronauts before and after flight. Results for anaerobic capacity have not been tabulated.

Rodgers, Sandra L.↗

NASA NTRS1992

Vascular uptake of rehydration fluids in hypohydrated men at rest and exercise

The purpose of this study was to formulate and to evaluate rehydration drinks, which would restore total body water and plasma volume (PV), for astronauts to consume before and during extravehicular activity, a few hours before reentry, and immediately after landing. In the first experiment (rest, sitting), five healthy men (23-41 yr), previously dehydrated for 24 hr., drank six (1a, 2, 4, 5, 6, 7) fluid formulations (one each at weekly intervals) and then sat for 70 min. Pre-test PV were measured with Evans blue dye and changes in PV were calculated with the hematocrit-hemoglobin transformation equation. This rest experiment simulated hypohydrated astronauts preparing for reentry. The second experiment (exercise, supine) followed the same protocol except four healthy men (30-46 yr) worked for 70 min. in the supine position on a cycle ergometer at a mean load of 71+/-1 percent of their peak aerobic work capacity. This exercise experiment simulated conditions for astronauts with reduced total body water engaging in extravehicular activity.

Greenleaf, J. E.↗

NASA NTRS1993

Human-in-the-loop evaluation of RMS Active Damping Augmentation

Active Damping Augmentation is the insertion of Controls-Structures Integration Technology to benefit the on-orbit performance of the Space Shuttle Remote Manipulator System. The goal is to reduce the vibration decay time of the Remote Manipulator System following normal payload maneuvers and operations. Simulation of Active Damping Augmentation was conducted in the realtime human-in-the-loop Systems Engineering Simulator at the NASA Johnson Space Center. The objective of this study was to obtain a qualitative measure of operational performance improvement from astronaut operators and to obtain supporting quantitative performance data. Sensing of vibratory motions was simulated using a three-axis accelerometer mounted at the end of the lower boom of the Remote Manipulator System. The sensed motions were used in a feedback control law to generate commands to the joint servo mechanisms which reduced the unwanted oscillations. Active damping of the Remote Manipulator System with an attached 3990 lb. payload was successfully demonstrated. Six astronaut operators examined the performance of an Active Damping Augmentation control law following single-joint and coordinated six-joint translational and rotational maneuvers. Active Damping Augmentation disturbance rejection of Orbiter thruster firings was also evaluated. Significant reductions in the dynamic response of the 3990 lb. payload were observed. Astronaut operators recommended investigation of Active Damping Augmentation benefits to heavier payloads where oscillations are a bigger problem (e.g. Space Station Freedom assembly operators).

Demeo, Martha E.↗

NASA NTRS1993

Spaceflight Radiation Health program at the Lyndon B. Johnson Space Center

The Johnson Space Center leads the research and development activities that address the health effects of space radiation exposure to astronaut crews. Increased knowledge of the composition of the environment and of the biological effects of space radiation is required to assess health risks to astronaut crews. The activities at the Johnson Space Center range from quantification of astronaut exposures to fundamental research into the biological effects resulting from exposure to high energy particle radiation. The Spaceflight Radiation Health Program seeks to balance the requirements for operational flexibility with the requirement to minimize crew radiation exposures. The components of the space radiation environment are characterized. Current and future radiation monitoring instrumentation is described. Radiation health risk activities are described for current Shuttle operations and for research development program activities to shape future analysis of health risk.

Johnson, A. Steve↗

NASA NTRS1993

Design of a recumbent seating system

Future space shuttle missions presented by NASA might require the shuttle to rendezvous with the Russian space station Mir for the purpose of transporting astronauts back to earth. Due to the atrophied state of these astronauts, a special seating system must be designed for their transportation. The main functions of this seating system are to support and restrain the astronauts during normal reentry flight and to dampen some of the loading that might occur in a crash situation. Through research, the design team developed many concept variants for these functional requirements. By evaluating each variant, the concepts were eliminated until the four most attractive designs remained. The team used a decision matrix to determine the best concept to carry through embodiment. This concept involved using struts for support during reentry flight and a spring damper/shock absorber system to dampen crash landing loads. The embodiment design process consisted of defining the layout of each of the main functional components, specifically, the seat structure and the strut structure. Through the use of MCS/pal two, the design was refined until it could handle all required loads and dampen to the forces specified. The auxiliary function carriers were then considered. Following the design of these components, the complete final layout could be determined. It is concluded that the final design meets all specifications outlined in the conceptual design. The main advantages of this design are its low weight, simplicity, and large amount of function sharing between different components. The disassembly of this design could potentially present a problem because of time and size constraints involved. Overall, this design meets or exceeds all functional requirements.

Croyle, Scott↗