Results for “enumerators” — Page 12

NASA NTRS1991

New research on bioregenerative air/water purification systems

For the past several years, air and water purification systems have been developed and used. This technology is based on the combined activities of plants and microorganisms as they function in a natural environment. More recently, researchers have begun to address the problems associated with indoor air pollution. Various common houseplants are currently being evaluated for their abilities to reduce concentrations of volatile organic compounds (VOCS) such as formaldehyde and benzene. With development of the Space Exploration Initiative, missions will increase in duration, and problems with resupply necessitates implementation of regenerative technology. Aspects of bioregenerative technology have been included in a habitat known as the BioHome. The ultimate goal is to use this technology in conjunction with physicochemical systems for air and water purification within closed systems. This study continued the risk assessment of bioregenerative technology with emphasis on biological hazards. In an effort to evaluate the risk for human infection, analyses were directed at enumeration of fecal streptococci and enteric viruses with the BioHome waste water treatment system.

Johnson, Anne H.↗

NASA NTRS1988

Liquid rocket booster integration study. Volume 1: Executive summary

The impacts of introducing liquid rocket booster engines (LRB) into the Space Transportation System (STS)/Kennedy Space Center (KSC) launch environment are identified and evaluated. Proposed ground systems configurations are presented along with a launch site requirements summary. Prelaunch processing scenarios are described and the required facility modifications and new facility requirements are analyzed. Flight vehicle design recommendations to enhance launch processing are discussed. Processing approaches to integrate LRB with existing STS launch operations are evaluated. The key features and significance of launch site transition to a new STS configuration in parallel with ongoing launch activities are enumerated. This volume is the executive summary of the five volume series.

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NASA NTRS1988

Liquid Rocket Booster Integration Study. Volume 2: Study synopsis

The impacts of introducing liquid rocket booster engines (LRB) into the Space Transportation System (STS)/Kennedy Space Center (KSC) launch environment are identified and evaluated. Proposed ground systems configurations are presented along with a launch site requirements summary. Prelaunch processing scenarios are described and the required facility modifications and new facility requirements are analyzed. Flight vehicle design recommendations to enhance launch processing are discussed. Processing approaches to integrate LRB with existing STS launch operations are evaluated. The key features and significance of launch site transition to a new STS configuration in parallel with ongoing launch activities are enumerated. This volume is the study summary of the five volume series.

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NASA NTRS1988

Liquid rocket booster integration study. Volume 3, part 1: Study products

The impacts of introducing liquid rocket booster engines (LRB) into the Space Transportation System (STS)/Kennedy Space Center (KSC) launch environment are identified and evaluated. Proposed ground systems configurations are presented along with a launch site requirements summary. Prelaunch processing scenarios are described and the required facility modifications and new facility requirements are analyzed. Flight vehicle design recommendations to enhance launch processing are discussed. Processing approaches to integrate LRB with existing STS launch operations are evaluated. The key features and significance of launch site transition to a new STS configuration in parallel with ongoing launch activities are enumerated. This volume is part one of the study products section of the five volume series.

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NASA NTRS1988

Liquid rocket booster integration study. Volume 3: Study products. Part 2: Sections 8-19

The impacts of introducing liquid rocket booster engines (LRB) into the Space Transportation System (STS)/Kennedy Space Center (KSC) launch environment are identified and evaluated. Proposed ground systems configurations are presented along with a launch site requirements summary. Prelaunch processing scenarios are described and the required facility modifications and new facility requirements are analyzed. Flight vehicle design recommendations to enhance launch processing are discussed. Processing approaches to integrate LRB with existing STS launch operations are evaluated. The key features and significance of launch site transition to a new STS configuration in parallel with ongoing launch activities are enumerated. This volume is part two of the study products section of the five volume series.

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NASA NTRS1988

Liquid rocket booster integration study. Volume 5, part 1: Appendices

The impacts of introducing liquid rocket booster engines (LRB) into the Space Transportation System (STS)/Kennedy Space Center (KSC) launch environment are identified and evaluated. Proposed ground systems configurations are presented along with a launch site requirements summary. Prelaunch processing scenarios are described and the required facility modifications and new facility requirements are analyzed. Flight vehicle design recommendations to enhance launch processing are discussed. Processing approaches to integrate LRB with existing STS launch operations are evaluated. The key features and significance of launch site transition to a new STS configuration in parallel with ongoing launch activities are enumerated. This volume is the appendices of the five volume series.

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NASA NTRS1990

A perspective on CELSS control issues

Some issues of Closed Ecological Life Support System (CELSS) analysis and design are effectively addressed from a systems control perspective. CELSS system properties that may be elucidated using control theory in conjunction with mathematical and simulation modeling are enumerated. The approach that is being taken to the design of a control strategy for the Crop Growth Research Chamber (CGRC) and the relationship of that approach to CELSS plant growth unit subsystems control is described.

Blackwell, Ann L.↗

NASA NTRS1991

Sondrestrom radar measurements of the reconnection electric field

The possibility of using Sondrestrom incoherent radar scatter to estimate the rate of solar-wind energy transfer is examined by using plasma-velocity measurements in the separatrix reference frame. The separatrix is the boundary between open and closed field lines, and its orientation is deduced from all-sky images. The radar observations are used to determine the separatrix location and the ionospheric plasma drift. Measurements of the reconnection electric field in the midnight sector for one night are taken, revealing that the field is less than 15 mV/m during the time of local polar-cap extension. During polar-cap contraction the field range is 30-40 mV/m, and these periods correspond to substorm expansive phases. The limitations associated with measuring ionospheric plasma drift, the boundary orientation, and boundary location are enumerated. The measurements in the experimental case demonstrate the possibility of plasma transfer from closed to open field lines.

De La Beaujardiere, O.↗

NASA NTRS1990

Astrogam - A magnetic rigidity spectrometer for gamma-ray astronomy

A novel concept is presented for a high-energy gamma-ray telescope with an extended energy range and excellent energy and angular resolution. The characteristics of Astrogam, a wide-field camera which makes an all-sky survey, are enumerated. Consideration is given to the instrument's unique features: wide energy range (four orders of magnitude and energy, which will bridge the gap between satellite and ground-based observations); excellent source location precision (multiple scattering error dominating nuclear recoil and measurement error below 20 GeV); and excellent energy resolution (1-percent energy resolution). Astrogam will make observations in the GTE energy range possible and could resolve complex source regions like the Crab pulsar/Nebular system, the Galactic center, and the Geminga region as well as discover the true nature of the sources.

Adams, James H., Jr.↗

NASA NTRS1992

The phase 2 NRA

We present points of special interest to potential proposers for the Compton Observatory Phase 2 Guest Investigator (GI) program. A general summary of some of the most important details of the phase 2 NASA Research Announcement (NRA) is followed by an enumeration of the modes of participation and proposal types available to GI proposers. Finally, the method which is planned for the selection of the Phase 2 Guest Investigators in parallel with the development of a preliminary Phase 2 observing timeline is outlined. The ways in which the selection of targets by GI's could be affected by the Phase 2 timeline development procedure is described.

Chipman, Eric↗

NASA NTRS1992

Generalized hypercube structures and hyperswitch communication network

This paper discusses an ongoing study that uses a recent development in communication control technology to implement hybrid hypercube structures. These architectures are similar to binary hypercubes, but they also provide added connectivity between the processors. This added connectivity increases communication reliability while decreasing the latency of interprocessor message passing. Because these factors directly determine the speed that can be obtained by multiprocessor systems, these architectures are attractive for applications such as remote exploration and experimentation, where high performance and ultrareliability are required. This paper describes and enumerates these architectures and discusses how they can be implemented with a modified version of the hyperswitch communication network (HCN). The HCN is analyzed because it has three attractive features that enable these architectures to be effective: speed, fault tolerance, and the ability to pass multiple messages simultaneously through the same hyperswitch controller.

Young, Steven D.↗

NASA NTRS1991

Space Station Freedom capabilities for users

Space Station Freedom's major objectives are to prepare for human space exploration by providing a long-duration, continuously habitable spacecraft in low earth orbit for physiology studies and for development of systems to support human presence in space and to enable laboratory and observational research in space. As a result of restructuring and the preliminary design review, designs of Space Station Freedom architecture and systems have progressed to the point where the accommodations for users can be well described. These capabilities are enumerated, covering such important resources as power and cooling, rack volume and external accommodations, crew time, data and command rates, and acceleration environment. Related items such as total energy, data management systems, and interfaces, station attitude, payload transportation, and on board and ground facilities are considered.

Taylor, William W. L.↗

NASA NTRS1991

Development and (evidence for) destruction of biofilm with Pseudomonas aeruginosa as architect

Disinfection and maintenance of an acceptable level of asepsis in spacecraft potable water delivery systems is a formidable task. The major area of research for this project has been to monitor the formation and growth of biofilm, and biofilm attached microorganisms, on stainless steel surfaces (specifically coupons), and the use of ozone for the elimination of these species in a closed loop system. A number of different techniques have been utilized during the course of a typical run. Scraping and sonication of coupon surfaces with subsequent plating as well as epifluorescence microscopy have been utilized to enumerate biofilm protected Pseudomonas aeruginosa. In addition, scanning electron microscopy is the method of choice to examine the integrity of the biofilm. For ozone determinations, the indigo decolorization spectrophotometric method seems most reliable. Both high- and low-nutrient cultured P. aeruginosa organisms were the target species for the ozone disinfection experiments.

Uzcategui, Valerie N.↗

NASA NTRS1989

Launch site integration of Liquid Rocket Boosters

The impacts of introducing Liquid Rocket Boosters (LRB) into the STS/KSC launch environment are identified and evaluated. Proposed ground systems configurations are presented along with a launch site requirements summary. Pre-launch processing scenarios are described and the required facility modifications and new facility requirements are analyzed. Flight vehicle design recommendations to enhance launch processing are discussed. Processing approaches to integrate LRB with existing STS launch operations are evaluated. The key features and significance of launch site transition to a new STS configuration in parallel with ongoing launch activities are enumerated.

Scott, Leland P.↗

NASA NTRS1992

On the decoder error probability of block codes

By using coding and combinational techniques, an explicit formula is derived which enumerates the complete weight distribution of decodable words of block codes using partially known weight distributions. Also an approximation formula for nonbinary block codes is obtained. These results in turn give exact and approximate expressions for the decoder error probability PE(u) of block codes.

Cheung, Kar-Ming↗

NASA NTRS1992

Beamed microwave power transmission and its application to space

The general principles and special components of beamed microwave power transmission systems are outlined and their application to the space program are discussed. The beamed system is defined as starting with a dc source of power at the transmitting end, converting it to a microwave beam for transmission through space, and ending with the dc power output at the receiving end. An experimentally measured and certified dc-to-dc efficiency of 54 percent has been achieved, using this definition. The application discussed is that of a LEO to GEO transportation system that depends upon vehicles propelled by electric thrusters whose power is supplied by a microwave beam originating at the earth's surface. The advantages of the all-electronic system over a chemically propelled system are enumerated. The principles of space propulsion, particularly as they relate to electric propulsion, are outlined. Key components of the system and environmental considerations are discussed.

Brown, William C.↗

NASA NTRS1992

Laboratory simulation of aerothermodynamic phenomena - A review

The issues of laboratory simulation of aerothermodynamic phenomena are discussed. The paper first enumerates the seven aerothermodynamic phenomena that affect the performance of high speed aerospace vehicles but are presently beyond our ability to predict accurately, and defines the types of experiments that need to be made to understand and quantify the phenomena. The facilities suited for these experiments are identified. The causes of uncertainty and difficulty in the experiments are cited. The procedures for calibrating the facilities for these purposes are proposed, and the research and development needed for successful laboratory simulation of aerothermodynamic phenomena are identified.

Park, Chul↗

NASA NTRS1992

The LDCE Particle Impact Experiment as flown on STS-46

Many materials and techniques have been developed by the authors to sample the flux of particles in Low Earth Orbit (LEO). Though regular in-site sampling of the flux in LEO the materials and techniques have produced data which compliment the data now being amassed by the Long Duration Exposure Facility (LDEF) research activities. Orbital debris models have not been able to describe the flux of particles with d sub p less than or = 0.05 cm, because of the lack of data. Even though LDEF will provide a much needed baseline flux measurement, the continuous monitoring of micron and sub-micron size particles must be carried out. A flight experiment was conducted on the Space Shuttle as part of the LDCE payload to develop an understanding of the Spatial Density (concentration) as a function of size (mass) for particle sizes 1 x 10(exp 6) cm and larger. In addition to the enumeration of particle impacts, it is the intent of the experiment that hypervelocity particles be captured and returned intact. Measurements will be performed post flight to determine the flux density, diameters, and subsequent effects on various optical, thermal control and structural materials. In addition to these principal measurements, the Particle Impact Experiment (PIE) also provides a structure and sample holders for the exposure of passive material samples to the space environment, e.g., thermal cycling, and atomic oxygen, etc. The experiment will measure the optical property changes of mirrors and will provide the fluence of the ambient atomic oxygen environment to other payload experimenters. In order to augment the amount of material returned in a form which can be analyzed, the survivability of the experiment as well as the captured particles will be assessed. Using Sandia National Laboratory's hydrodynamic computer code CTH, hypervelocity impacts on the materials which comprise the experiments have been investigated and the progress of these studies are reported.

Maag, Carl R.↗