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At least 235 records · Page 13

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NASA NTRS1981

Experiences in Delta mission planning

The Delta launch vehicle has experienced 153 successful launches since 1960 and 40 more are scheduled. Relying on up-to-date technology and proven flight hardware, the Delta vehicle has been used for low to high circular and geosynchronous transfer orbits, high elliptic probes, and lunar and planetary missions. A history of Delta launches and configuration modifications is presented, noting a 92-95% success rate and its cost effective role in reimbursable missions. Elements of mission planning such as feasibility studies (1-3 yrs), spacecraft restraints manuals, reference trajectories, preliminary mission analysis, detailed test objectives, range/safety studies, guided nominal trajectory, and mission specific studies are discussed. Trajectory shaping determines vehicle and spacecraft restraints, optimizes the trajectory, and maximizes the payload capabilities. Improvements in the Delta vehicle have boosted payloads from 100 to 2890 lbs., improving the price per pound ratio, as costs have risen, only by a factor of three. Current launch schedules extend well into 1985.

Kork, J.↗

NASA NTRS1981

Radiographic evidence of disuse osteoporosis in the monkey /M. nemestrina/

Radiological techniques were utilized for monitoring progressive changes in compact bone in the tibia of monkeys during experimentally induced osteopenia. Bone mass loss in the tibia during restraint was evaluated from radiographs, from bone mineral analysis, and from images reconstructed from gamma ray computerized tomography. The losses during 6 months of restraint tended to occur predominantly in the proximal tibia and were characterized by subperiosteal bone loss, intracortical striations, and scalloped endosteal surfaces. Bone mineral content in the cross section of the tibia declined 17-21%. In 6 months of recovery, the mineral content of the proximal tibia remained depressed.

Young, D. R.↗

NASA NTRS1982

Daily rhythms of activity and temperature of Macaca nemestrina

The activity and temperature rhythms of pig-tailed macaques (Macaca nemestrina) maintained in LD 16:8 at 25 C in specially designed restraint chairs have been examined. Activity was monitored via a sensor that was attached to the restraint chair. Temperature was monitored at the axilla, ankle and ear. All variables showed prominent day-night variations, and except for ankle temperature, had highest values during the daytime. These results show that the regulation of the daily rhythm of body temperature involves anatomical sites that are utilized in a temporally distinct fashion.

Sulzman, F. M.↗

NASA NTRS1983

Stability, vibration and passive damping of partially restrained imperfect columns

A theoretical and experimental study of slender tubular columns for possible use in space structures is conducted in the presence of partial rotational end restraints. Explicit formulas are derived for computing the buckling load and the lowest natural frequency of perfectly straight uniform elastic members with rotational end restraints possessing linear moment-rotation characteristics. An exact solution in the form of a transcendental equation, and a numerical solution using second-order finite-differences are also presented. The presence of an initial imperfection is also incorporated into the numerical procedure. Vibration tests are conducted on an imperfect tubular steel member in the absence of an axial load. A damping concept consisting of a string-mass assembly is explored. Three passive damping configurations involving combinations of three lead shots were investigated. The three lead shot configurations provided considerably greater damping than the single lead shot.

Razzaq, Z.↗

NASA NTRS1983

The effects of immobilization on cortical bone in monkeys (M. nemestrina)

Rhesus and pigtail monkeys were restrained for up to seven months in a hypogravic-hypodynamic environment for the purpose of studying the osteoporotic process and its reversibility, particularly in relation to humans. In vivo bending, radiography and tomography are among the techniques that were used. Bone deterioration within one month was detectable only in histological preparation, where resorption and subsequent cavity formation were demonstrated in addition to demineralization of the remaining hard tissue. Norland bone mineral analysis showed the greatest bone demineralization in the proximal tibia (23 percent to 31 percent after six months restraint), recovery did not even necessarily occur after 15 months. The largest bone stiffness decrease was 36 to 40 percent after a six months restraint; normal bending properties but not mineral content were restored after 8-1/2 months. Contrary to earlier studies, it is concluded that bone recovery, though a lengthy process, is possible: cortical bone in the tibia required 40 months.

Niklowitz, W. J.↗

NASA NTRS1985

Challenges of developing an electro-optical system for measuring man's operational envelope

In designing work stations and restraint systems, and in planning tasks to be performed in space, a knowledge of the capabilities of the operator is essential. Answers to such questions as whether a specific control or work surface can be reached from a given restraint and how much force can be applied are of particular interest. A computer-aided design system has been developed for designing and evaluating work stations, etc., and the Anthropometric Measurement Laboratory (AML) has been charged with obtaining the data to be used in design and modeling. Traditional methods of measuring reach and force are very labor intensive and require bulky equipment. The AML has developed a series of electro-optical devices for collecting reach data easily, in computer readable form, with portable systems. The systems developed, their use, and data collected with them are described.

Woolford, B.↗

NASA NTRS1985

Remote control of an impact demonstration vehicle

Uplink and downlink telemetry systems were installed in a Boeing 720 aircraft that was remotely flown from Rogers Dry Lake at Edwards Air Force Base and impacted into a designated crash site on the lake bed. The controlled impact demonstration (CID) program was a joint venture by the National Aeronautics and Space Administration (NASA) and the Federal Aviation Administration (FAA) to test passenger survivability using antimisting kerosene (AMK) to inhibit postcrash fires, improve passenger seats and restraints, and improve fire-retardent materials. The uplink telemetry system was used to remotely control the aircraft and activate onboard systems from takeoff until after impact. Aircraft systems for remote control, aircraft structural response, passenger seat and restraint systems, and anthropomorphic dummy responses were recorded and displayed by the downlink stems. The instrumentation uplink and downlink systems are described.

Harney, P. F.↗

NASA NTRS1985

ACCESS (Assembly Concept for Construction of Erectable Space Structure) - A Shuttle flight experiment

ACCESS is a planned Shuttle flight experiment to assess the potential of an on-orbit construction concept designed for efficient manual assembly of a space truss. The experiment, which is scheduled for launch November 27, 1985, on the Space Transportation System (STS) flight 61-B, uses two astronauts secured in fixed foot restraints located in the Shuttle cargo bay to assemble a 45-foot long aluminum truss beam from 93 tubular struts and 33 nodal joints. Neutral buoyancy simulations of the flight experiment indicate the truss can be assembled in less than thirty minutes. Structural assembly, structural repair, flexible cable attachment and manual manipulation of the truss is also planned for the experiment using an astronaut secured in the Manipulator Foot Restraint attached to the Remote Manipulator System arm. Flight assembly data will be generated for correlation of the neutral buoyancy ground test data. This paper describes the ACCESS flight experiment and presents results of the neutral buoyancy development and training tests.

Heard, W. L., Jr.↗

NASA NTRS1987

Elastic Hinge for Solar-Cell Array

Elastic hinge folds to small thickness, allows easy replacement of panels attached, and provides part of torque for refolding without additional springs. Holds modules of solar-cell array. Modules kept in open position by external restraint. When restraint removed, elasticity of molybdenum hinge elements helps to fold facing modules together. Hinge developed for foldable modules for solar-cell panels.

Mills, R. M.↗

NASA NTRS1990

Aerospace Food Tray

Lightweight tray designed for use in microgravity. Provides restraint and thermal insulation for modular packages of food. Magnetic utensils restrained by attraction to ferrous plate mounted underneath. Restraints for pouch and spring clips also provided. Surfaces made smooth to facilitate cleaning, and number of cracks, crevices, and pits where food residues collect kept to minimum. Useful for serving meals in airplanes, boats, hospitals, and facilities that care for children.

Aragon, Maureen A.↗

NASA NTRS1991

Weldability of Weldalite (tm) 049 with and without TiB2 reinforcement

The effects are assessed of TiB2 reinforcement and parent alloy Li content on the weldability of Weldalite (tm) 049 type alloys. Welding trials were performed using either AC or DC polarity gas tungsten arc (GTA) welding according to described procedures. The welding was performed under conditions of high restraint on 5 cm (2 in) wide x 25.4 cm (10 in) long plates machined from the 0.952 cm (0.375 in) extruded bar parallel to the extrusion direction. A 37.5 deg bevel was machined on the center edge of the extruded bar. Cut rod filler wire was machined from three alloys, and one commercially available 2319 filler wire was also used. The preliminary assessment of the weldability revealed no propensity for hot cracking under conditions of high restraint. This result is significant, because hot cracking has been reported for all other leading aluminum lithium alloys welded with certain conventional filler alloys. The strengths for Weldalite parent welded with parent filler obtained were higher than those for alloys used in launch systems, such as 2219 and 2014 welded with 2319 and 4043 fillers, respectively. Even higher values were obtained by variable polarity plasma arc welding (e.g., 54 ksi (372 MPa) mean tensile strength).

Source record↗

NASA NTRS1993

Numerical simulation of vehicle crashworthiness and occupant protection

Numerical simulation of vehicle crashworthiness and occupant protection are addressed. The vehicle crashworthiness design objectives are to design the vehicle structure for optimum impact energy absorption, and to design the restraint system (seatbelts, airbags, bolsters, etc.) for optimum occupant protection. The following approaches are taken; a major part of the impact energy is to be absorbed by the vehicle structure; the restraint components will provide protection against the remaining crash energy; certain vehicle components are designed to deform under specific types and speeds of impact in a desired mode for sound energy management; structural components such as front side rails, rear rails, door structure and pillars undergo large amounts of deformation; and with properly designed geometry and material these components assist in mitigating the effects of impact.

Saha, Nripen K.↗

NASA NTRS1993

Strength capabilities and load requirements while performing torquing tasks in zero gravity

A generic examination of the loads produced by individuals performing maximal efforts with a torquing tool in zero gravity, to determine operator strength when performing torquing tasks; quantify the loads placed on foot restraints while performing these tasks; and examine effects of orientation and direction of tool rotation on strength effectiveness was conducted. The experiment was conducted aboard NASA's KC-135 reduced-gravity aircraft, using two force plates attached to a test stand, one with a foot restraint. Subjects used a wrench to apply maximum torques to various fittings, in different positions, in clockwise and counterclockwise directions. It was seen that these subjects could produce approximately 400 to 750 N of force, depending on the orientation of the tool and the direction of effort. The most force could be produced when pushing the tool upwards. A force effectiveness ratio (FER) defined as an indication of how much of the subjects' total effort actually went into performing the desired task. Values of FER ranged from 0.55 to 0.90, with the greatest FER occurring with UP and DOWN efforts, and the lowest with AWAY and LEFT efforts. Designers can use these results to set specifications for craft structures; tools can be developed based on the known strength of the tool users; and tasks can be developed to not exceed the crewmembers' capabilities.

Poliner, Jeffrey↗

NASA NTRS1992

Advanced Cardiac Life Support (ACLS) utilizing Man-Tended Capability (MTC) hardware onboard Space Station Freedom

Because of the time and distance involved in returning a patient from space to a definitive medical care facility, the capability for Advanced Cardiac Life Support (ACLS) exists onboard Space Station Freedom. Methods: In order to evaluate the effectiveness of terrestrial ACLS protocols in microgravity, a medical team conducted simulations during parabolic flights onboard the KC-135 aircraft. The hardware planned for use during the MTC phase of the space station was utilized to increase the fidelity of the scenario and to evaluate the prototype equipment. Based on initial KC-135 testing of CPR and ACLS, changes were made to the ventricular fibrillation algorithm in order to accommodate the space environment. Other constraints to delivery of ACLS onboard the space station include crew size, minimum training, crew deconditioning, and limited supplies and equipment. Results: The delivery of ACLS in microgravity is hindered by the environment, but should be adequate. Factors specific to microgravity were identified for inclusion in the protocol including immediate restraint of the patient and early intubation to insure airway. External cardiac compressions of adequate force and frequency were administered using various methods. The more significant limiting factors appear to be crew training, crew size, and limited supplies. Conclusions: Although ACLS is possible in the microgravity environment, future evaluations are necessary to further refine the protocols. Proper patient and medical officer restraint is crucial prior to advanced procedures. Also emphasis should be placed on early intubation for airway management and drug administration. Preliminary results and further testing will be utilized in the design of medical hardware, determination of crew training, and medical operations for space station and beyond.

Smith, M.↗

NASA NTRS1992

A surgical support system for Space Station Freedom

Surgical techniques in microgravity are being developed for the Health Maintenance Facility (HMF) on Space Station Freedom (SSF). This will be a presentation of the proposed surgical capabilities and ongoing hardware and procedural investigations. Methods: Procedures and prototype hardware, which include a medical restraint system, a surgical overhead isolation canopy, a suction device, and a regional laminar flow device were evaluated. This was accomplished by realistic sterile surgical simulations involving both mannequins and animals during KC-135 parabolic flight and in a high fidelity ground based HMF mockup. Results: Animal surgery in the environment of microgravity allowed the observation of unique arterial and venous bleeding characteristics for the first time. The ability to control bleeding and to prevent cabin atmosphere contamination was also demonstrated. Conclusions: The procedures and prototype hardware tested provided valuable information and should be investigated and developed further. The use of standard surgical techniques are possible in microgravity if the principles of personnel and supply restraint and operative field containment are adhered to.

Campbell, M. R.↗

NASA NTRS1960

Centrifuge Study of Pilot Tolerance to Acceleration and the Effects of Acceleration on Pilot Performance

A research program the general objective of which was to measure the effects of various sustained accelerations on the control performance of pilots, was carried out on the Aviation Medical Acceleration Laboratory centrifuge, U.S. Naval Air Development Center, Johnsville, PA. The experimental setup consisted of a flight simulator with the centrifuge in the control loop. The pilot performed his control tasks while being subjected to acceleration fields such as might be encountered by a forward-facing pilot flying an atmosphere entry vehicle. The study was divided into three phases. In one phase of the program, the pilots were subjected to a variety of sustained linear acceleration forces while controlling vehicles with several different sets of longitudinal dynamics. Here, a randomly moving target was displayed to the pilot on a cathode-ray tube. For each combination of acceleration field and vehicle dynamics, pilot tracking accuracy was measured and pilot opinion of the stability and control characteristics was recorded. Thus, information was obtained on the combined effects of complexity of control task and magnitude and direction of acceleration forces on pilot performance. These tests showed that the pilot's tracking performance deteriorated markedly at accelerations greater than about 4g when controlling a lightly damped vehicle. The tentative conclusion was also reached that regardless of the airframe dynamics involved, the pilot feels that in order to have the same level of control over the vehicle, an increase in the vehicle dynamic stability was required with increases in the magnitudes of the acceleration impressed upon the pilot. In another phase, boundaries of human tolerance of acceleration were established for acceleration fields such as might be encountered by a pilot flying an orbital vehicle. A special pilot restraint system was developed to increase human tolerance to longitudinal decelerations. The results of the tests showed that human tolerance of longitudinal deceleration forces was considerably improved through use of the special restraint system.

Creer, Brent Y.↗

NASA NTRS1998

Thermal Vacuum Testing of the Crew and Equipment Translation Aid for the International Space Station

The Crew and Equipment Translation Aid (CETA) is a human powered cart that will aid astronauts in conducting extra-vehicular activity (EVA) maintenance on the International Space Station (ISS). There are two critical EVA tasks relevant to the successful operation of the CETA. These are the removal of the launch restraint bolts during its initial deployment from the Space Shuttle payload bay and the manual deceleration of the cart, its two onboard astronauts, and a payload. To validate the launch restraint and braking system designs, the hardware engineers needed to verify their performance in an environment similar to that in which it will be used. This environment includes the vacuum of low earth orbit and temperatures as low as -11O F and as high as +200 F. The desire for quantitative data, as opposed to subjective information which could be provided by a suited astronaut, coupled with test scheduling conflicts resulted in an unmanned testing scenario. Accommodating these test objectives in an unmanned test required a solution that would provide remotely actuated thermal vacuum compatible torque sources of up to 25 ft-lbs at four horizontally oriented and four vertically oriented bolts, a variable input force of up to 125 lbs at the four brake actuators, and thermal vacuum compatible torque and force sensors. The test objectives were successfully met in both the thermal Chamber H and the thermal vacuum Chamber B at NASA's Johnson Space Center.

Blanco, Raul A.↗

NASA NTRS1976

Bone Formation Rate in Experimental Disuse Osteoporosis in Monkeys

Specific mechanisms underlying weightless and hypodynamic bone loss are obscure. A principal relationship which must be affected is the balance between bone formation and bone resorption rates. In order to better define the influence of those parameters on bone loss, and also to develop measurements in other species as a useful adjunct to human research, studies were undertaken with experimental monkeys. Tests were conducted with a total of 6 adult male monkeys, weighing 10-13 kg, and approximately 10-12 yrs. of age to evaluate specifically bone formation rate during the development of disuse osteoporosis and osteopenia. Three animals were restrained in a semi-recumbent position for six months; three animals served as normal caged controls. Food intake (Purina) was held relatively constant at 200g/day for each animal. Using a Norland Bone Mineral Analyzer, bone mineral losses of 3.5 to 6% were seen in the mid-shaft of the tibia and in the distal radius. Bone loss was confirmed radiographically, with observation of thinning of the proximal tibial cortex and trabeculae in the calcaneus. Bone formation rate was determined using standard Ca-47 kinetics under metabolic balance conditions. After six months of restraint, accretion was 7.2-13.2 mg Ca/kg/day, compared to 3.2-4.1 mg Ca/kg/day in caged controls and 3-8 mg Ca/kg/day in normal adult humans. Fecal and urine calcium was 25-40% higher in restrained animals than in controls. Dietary calcium absorption decreases during restraint, and calcium turnover increases, implying a rise in bone resorption rate concommitant with the observed rise in bone accretion rate. Further studies dealing specifically with bone resorption are underway to define this more fully.

Cann, Christopher↗