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At least 343 records · Page 19

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NASA NTRS2001

Feasibility Study of Thin Film Thermocouple Piles

Historically, thermopile detectors, generators, and refrigerators based on bulk materials have been used to measure temperature, generate power for spacecraft, and cool sensors for scientific investigations. New potential uses of small, low-power, thin film thermopiles are in the area of microelectromechanical systems since power requirements decrease as electrical and mechanical machines shrink in size. In this research activity, thin film thermopile devices are fabricated utilizing radio frequency sputter coating and photoresist lift-off techniques. Electrical characterizations are performed on two designs in order to investigate the feasibility of generating small amounts of power, utilizing any available waste heat as the energy source.

Sisk, R. C.↗

NASA NTRS1990

Cryogenic On-Orbit Liquid Depot Storage, Acquisition, and Transfer satellite (COLD-SAT) feasibility study

The Cryogenic On-Orbit Liquid Depot Storage, Acquisition, and Transfer Satellite (COLD-SAT) is an experimental spacecraft launched from an expendable launch vehicle which is designed to investigate the systems and technologies required for efficient, effective, and reliable management of cryogenic fluid in the reduced gravity space environment. The COLD-SAT program will provide the necessary data base and provide low-g proving of fluid and thermal models of cryogenic storage, transfer, and resupply concepts and processes. A conceptual approach was developed and an overview of the results of the 24 month COLD-SAT Phase A feasibility is described which includes: (1) a definition of the technology needs and the accompanying experimental 3 month baseline mission; (2) a description of the experiment subsystem, major features and rationale for satisfaction of primary and secondary experiment requirements using liquid hydrogen as the test fluid; and (3) a presentation of the conceptual design of the COLD-SAT spacecraft subsystems which support the on-orbit experiment with emphasis on areas of greatest challenge.

Bailey, William J.↗

NASA NTRS1993

Precipitation measurement using SIR-C: A feasibility study. Investigation at nadir

The most significant limitation of the imaging SAR in rain measurements is the ground return coupled to the rain cell. Here we report a study of the possibility of using the X-SAR and the C-band channel of SIR-C for rain measurement. Earlier signal-to-clutter calculations rule out the use of X-SAR at steeper off-vertical angles of incidence (i.e., 20 less than theta less than 50). Only rain rates greater than 30 mm/hr at angles of incidence greater than 60 degrees showed good signal-to-clutter ratio (SCR). This study involved calculations at vertical incidence. There is adequate signal-to-noise ratio (SNR) at vertical incidence, but the presence of high-range side-lobe levels leads to small SCR for measurement over oceans at both X and C bands. For larger rain thickness (greater than two km), the SCR gets better and smaller rain rates (greater than 10 mm/hr) can be measured. However, rain measurements over forests seem to be feasible at nadir even for smaller rain thickness (less than two km). We conclude that X band may be usable over the forest at vertical incidence to measure rain rates greater than five mm/hr even for shallow rain thickness and over ocean for large rain thickness.

Ahamad, Atiq↗

NASA NTRS1971

A feasibility study of heat-pipe-cooled leading edges for hypersonic cruise aircraft

A theoretical study of the use of heat pipe structures for cooling the leading edges of hypersonic cruise aircraft was carried out over a Mach number range of 6 to 12. Preliminary design studies showed that a heat pipe cooling structure with a 33-in. chordwise length could maintain the maximum temperature of a 65 deg sweepback wing with a 0.5-in. leading edge radius below 1600 F during cruise at Mach 8. A few relatively minor changes in the steady-state design of the structure were found necessary to insure satisfactory cooling during the climb to cruise speed and altitude. It was concluded that heat pipe cooling is an attractive, feasible technique for limiting leading edge temperatures of hypersonic cruise aircraft.

Silverstein, C. C.↗

NASA NTRS1973

Feasibility study of an Integrated Program for Aerospace vehicle Design (IPAD). Volume 1A: Summary

IPAD was defined as a total system oriented to the product design process. This total system was designed to recognize the product design process, individuals and their design process tasks, and the computer-based IPAD System to aid product design. Principal elements of the IPAD System include the host computer and its interactive system software, new executive and data management software, and an open-ended IPAD library of technical programs to match the intended product design process. The basic goal of the IPAD total system is to increase the productivity of the product design organization. Increases in individual productivity were feasible through automation and computer support of routine information handling. Such proven automation can directly decrease cost and flowtime in the product design process.

Miller, R. E., Jr.↗

NASA NTRS2001

Using Wearable Computers in Shuttle Processing: A Feasibility Study

Shuttle processing operations are performed following prescribed instructions compiled in a Work Authorization Document (WAD). Until very recently, WADs were printed so that they could be properly executed, including the buy off of each and every step by the appropriate authorizing agent. However, with the development of EPICs, Maximo, and PeopleSoft applications, some of these documents are now available in electronic format; hence, it is possible for technicians and engineers to access them on line and buy off the steps electronically. To take full advantage of these developments, technicians need access to such documents at the point of job execution. Body wearable computers present an opportunity to develop a WAD delivery system that enables access while preserving technician's mobility, safety levels, and quality of work done. The primary objectives of this project were to determine if body wearable computers are a feasible delivery system for WADs. More specifically, identify and recommend specific brands of body wearable computers readily available on the market. Thus, this effort has field-tested this technology in two areas of shuttle processing, and it has examined the usability of the technology. Results of two field tests and a Human Factors Usability Test are presented. Section 2 provides a description of the body wearable computer technology. Section 3 presents the test at the Space Shuttle Main Engine (SSME) Shop. Section 4 presents the results of the integration test at the Solid Rocket Boosters Assembly and Refurbishing Facility (SRBARF). Section 5 presents the results of the usability test done at the Operations Support Building (OSB).

Centeno, Martha A.↗

NASA NTRS2011

Material Testing in Support of the ISS Electrochemical Disinfection Feasibility Study

The International Space Station Program recognizes the risk of microbial contamination in their potable and non-potable water sources. With the end of the Space Shuttle Program, the ability to send up shock-kits of biocides in the event of an outbreak becomes even more difficult. Currently, the US Segment water system relies primarily on iodine to mitigate contamination concerns. To date, several small cases of contamination have occurred which have been remediated. NASA, however, realizes that having a secondary method of combating a microbial outbreak is a prudent investment. NASA is looking into developing hardware that can generate biocides electrochemically, and potentially deploying that hardware. The specific biocides that the technology could generate include: hydrogen peroxide, oxone, hypochlorite and peracetic acid. In order to use these biocides on deployed water systems, the project must determine that all the materials in the potential application are compatible with the biocides at their anticipated administered concentrations. This paper will detail the materials test portion of the feasibility assessment including the plan for both metals and non-metals along with results to date.

Clements, Anna↗

NASA NTRS1993

A feasibility study of a microgravity enhancement system for Space Station Freedom

The current low frequency microgravity requirements for Space Station Freedom (SSF) call for a level of less than 1 micro-g over 50 percent of all the laboratory racks for continuous periods of 30 days for at least 180 days per year. While this requirement is attainable for some of the laboratory modules for the Permanently Manned Configuration (PMC), it cannot be met for the Man-Tended Configuration (MTC). To improve the microgravity conditions in the laboratory modules, the Microgravity Enhancement System (MESYS) will apply a continuous thrust to SSF, to negate the disturbing gravity gradient and drag forces. The MESYS consists of a sensor, continuous throttle-able thrusters, and a control system. Both a proof mass system and nano-g accelerometer were evaluated for use as the sensor. The net result of the MESYS will be to shift the microgravity contours from the center of mass to a chosen location. Results indicate the MESYS is not feasible for the MTC since it will require 5073 kg of hydrazine fuel and 7660 watts of electrical power for 30 days of operation during average atmospheric conditions. For the PMC, the MESYS is much more practical, since only 4008 kg of fuel and 5640 watts of electrical power will be required for 30 days of operation during average atmospheric conditions.

Diamond, Preston S.↗

NASA NTRS1993

A feasibility study of a microgravity enhancement system for Space Station Freedom

The current low frequency microgravity requirements for Space Station Freedom (SSF) call for a level of less than 1 micro-g over 50 percent of all the laboratory racks for continuous periods of 30 days for at least 180 days per year. While this requirement is attainable for some of the laboratory modules for the Permanently Manned Configuration (PMC), it can not be met for the Man-Tended Configuration (MTC). In addition, many experiments would prefer even lower acceleration levels. To improve the microgravity environment, the Microgravity Enhancement System (MESYS) will apply a continuous thrust to SSF, to negate the disturbing gravity gradient and drag forces. The MESYS consists of a sensor, throttle-able thrusters and a control system. Both a proof mass system and accelerometer were evaluated for use as the sensor. The net result of the MESYS will be to shift the microgravity contours from the center of mass to a chosen location. Results indicate the MESYS is not feasible for MTC since it will require 5,073 kg of hydrazine fuel and 7,660 watts of power for 30 days of operation during average atmospheric conditions. For PMC, the MESYS is much more practical since only 4,008 kg of fuel and 5,640 watts of power are required.

Diamond, Preston S.↗

NASA NTRS1979

Systems level feasibility study for the detection of extra-solar planets. Volume 1: Infrared interferometer (IRIS) known as the Stanford Concept

A sensor system for the direct detection of extrasolar planets from an Earth orbit is evaluated: a spinning, infrared interferometer (IRIS). It is shuttle deployed, free flying, requires no on-orbit assembly and no reservicing over a design life of five years. The sensor concept and the mission objectives are reviewed, and the performance characteristics of a baseline sensor for standard observation conditions are derived. A baseline sensor design is given and the enabling technology discussed. Cost and weight estimates are performed; and a schedule for an IRIS program including technology development and assessment of risk are given. Finally, the sensor is compared with the apodized visual telescope sensor (APOTS) proposed for the same mission. The major conclusions are: that with moderate to strong technology advances, particularly in the fields of long life cryogenics, dynamical control, mirror manufacturing, and optical alignment, the detection of a Jupiter like planet around a Sunlike star at a distance of 30 light years is feasible, with a 3 meter aperture and an observation time of 1 hour. By contrast, major and possibly unlikely breakthroughs in mirror technology are required for APOTS to match this performance.

Source record↗

NASA NTRS2020

A Digital Twin Feasibility Study (Part II):Non-Deterministic Predictions of Fatigue Life Using In-Situ Diagnostics and Prognostics

The Digital Twin (DT) concept has the potential to revolutionize the way systems and their components are designed, managed, maintained, and operated across a vast number of fields from engineering to healthcare. The focus of this work is the implementation of DT for the health management of fatigue critical structures. This paper is the second part of a two-part series. The first of the series demonstrated the use of multi-scale, initiation-to-failure crack growth modeling to form non-deterministic predictions of fatigue life. In this second part, a general method for reducing uncertainty in fatigue life predictions is presented that couples in-situ diagnostics and prognostics in a probabilistic framework. Monte Carlo methods and high-fidelity finite element models are used to (i) generate probabilistic estimates of crack state throughout the life of the same geometrically complex test specimen and (ii) predict fatigue life with decreasing uncertainty as more of these diagnoses are obtained. The ability to predict accurately and in the presence of uncertainty is demonstrated, suggesting that the proposed DT method is feasible for fatigue life prognosis and should be pursued further with a focus on increasing application realism.

Patrick E Leser↗

NASA NTRS2006

Feasibility Study of Jupiter Icy Moons Orbiter Permanent Magnet Alternator Start Sequence

The Jupiter Icy Moons Orbiter (JIMO) mission was a proposed, (recently cancelled) long duration science mission to study three moons of Jupiter: Callisto, Ganymede, and Europa. One design of the JIMO spacecraft used a nuclear heat source in conjunction with a Brayton rotating machine to generate electrical power for the electric thrusters and the spacecraft bus. The basic operation of the closed cycle Brayton system was as follows. The working fluid, a heliumxenon gas mixture, first entered a compressor, then went through a recuperator and hot-side heat exchanger, then expanded across a turbine that drove an alternator, then entered the cold-side of the recuperator and heat exchanger and finally returned to the compressor. The spacecraft was to be launched with the Brayton system off-line and the nuclear reactor shut down. Once the system was started, the helium-xenon gas would be circulated into the heat exchangers as the nuclear reactors were activated. Initially, the alternator unit would operate as a motor so as to drive the turbine and compressor to get the cycle started. This report investigated the feasibility of the start up sequence of a permanent magnet (PM) machine, similar in operation to the alternator unit, without any position or speed feedback sensors ("sensorless") and with a variable load torque. It is found that the permanent magnet machine can start with sensorless control and a load torque of up to 30 percent of the rated value.

Kenny, Barbara H.↗

NASA NTRS1996

Feasibility Study of a Rotorcraft Health and Usage Monitoring System ( HUMS): Usage and Structural Life Monitoring Evaluation

The objective of this study was to evaluate two techniques, Flight Condition Recognition (FCR) and Flight Load Synthesis (FLS), for usage monitoring and assess the potential benefits of extending the retirement intervals of life-limited components, thus reducing the operator's maintenance and replacement costs. Both techniques involve indirect determination of loads using measured flight parameters and subsequent fatigue analysis to calculate the life expended on the life-limited components. To assess the potential benefit of usage monitoring, the two usage techniques were compared to current methods of component retirement. In addition, comparisons were made with direct load measurements to assess the accuracy of the two techniques. The data that was used for the evaluation of the usage monitoring techniques was collected under an independent HUMS Flight trial program, using a commercially available HUMS and data recording system. The usage data collect from the HUMS trial aircraft was analyzed off-line using PC-based software that included the FCR and FLS techniques. In the future, if the technique prove feasible, usage monitoring would be incorporated into the onboard HUMS.

Dickson, B.↗

NASA NTRS2004

Spaceflight Operations Services Grid (SOSG) Prototype Implementation and Feasibility Study

Science Operations Services Grid is focusing on building a prototype grid-based environment that incorporates existing and new spaceflight services to enable current and future NASA programs with cost savings and new and evolvable methods to conduct science in a distributed environment. The Science Operations Services Grid (SOSG) will provide a distributed environment for widely disparate organizations to conduct their systems and processes in a more efficient and cost effective manner. These organizations include those that: 1) engage in space-based science and operations, 2) develop space-based systems and processes, and 3) conduct scientific research, bringing together disparate scientific disciplines like geology and oceanography to create new information. In addition educational outreach will be significantly enhanced by providing to schools the same tools used by NASA with the ability of the schools to actively participate on many levels in the science generated by NASA from space and on the ground. The services range from voice, video and telemetry processing and display to data mining, high level processing and visualization tools all accessible from a single portal. In this environment, users would not require high end systems or processes at their home locations to use these services. Also, the user would need to know minimal details about the applications in order to utilize the services. In addition, security at all levels is an underlying goal of the project. The Science Operations Services Grid will focus on four tools that are currently used by the ISS Payload community along with nine more that are new to the community. Under the prototype four Grid virtual organizations PO) will be developed to represent four types of users. They are a Payload (experimenters) VO, a Flight Controllers VO, an Engineering and Science Collaborators VO and an Education and Public Outreach VO. The User-based services will be implemented to replicate the operational voice, video, telemetry and commanding systems. Once the User-based services are in place, they will be analyzed to establish feasibility for Grid enabling. If feasible then each User-based service will be Grid enabled. The remaining non-Grid services if not already Web enabled will be so enabled. In the end, four portals will be developed one for each VO. Each portal will contain the appropriate User-based services required for that VO to operate.

Bradford, Robert N.↗

NASA NTRSDate not supplied