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NASA NTRS2016

Selection of a Brine Processor Technology for NASA Manned Missions

The current ISS Water Recovery System (WRS) reclaims water from crew urine, humidity condensate, and Sabatier product water. Urine is initially processed by the Urine Processor Assembly (UPA) which recovers 75% of the urine as distillate. The remainder of the water is present in the waste brine which is currently disposed of as trash on ISS. For future missions this additional water must be reclaimed due to the significant resupply penalty for missions beyond Low Earth Orbit (LEO). NASA has pursued various technology development programs for a brine processor in the past several years. This effort has culminated in a technology down-select to identify the optimum technology for future manned missions. The technology selection is based on various criteria, including mass, power, reliability, maintainability, and safety. Beginning in 2016 the selected technology will be transitioned to a flight hardware program for demonstration on ISS. This paper summarizes the technology selection process, the competing technologies, and the rationale for the technology selected for future manned missions.

Carter, Donald L.↗

NASA NTRS2016

Launch Vehicle Selection and the Implementation of the Soil Moisture Active Passive Mission

Soil Moisture Active Passive (SMAP) is a NASA-developed Earth science satellite currently mapping the soil moisture content and freeze/thaw state of Earth's land mass from a 685km, near-polar, sun-synchronous orbit. It was launched on January 31, 2015 from Vandenberg AFB upon a Delta II 7320 launch vehicle. Due to external considerations, SMAP's launch vehicle selection remained an open item until Project Critical Design Review (CDR). Thus, certain key aspects of the spacecraft design had to accommodate a diverse range of candidate launch vehicle environments, performance envelopes, interfaces and operational scenarios. Engineering challenges stemmed from two distinct scenarios: decisions that had to be made prior to launch vehicle selection to accommodate all possible outcomes, and post-selection changes constrained by schedule and the existing spacecraft configuration. The effects of the timing of launch vehicle selection reached virtually every aspect of the Observatory's design and development. Physical environments, mass allocations, material selections, propulsion system performance, dynamic response, launch phase and mission planning, overall size and configuration, and of course all interfaces to the launch vehicle were heavily dependent on this outcome. This paper will discuss the resolution of these technical challenges.

Sherman, Sarah↗

NASA NTRSDate not supplied

Metrics in Space Life Support Technology Selection

Engineering metrics are useful in space life support technology selection, but they must be carefully used. Metrics are only part of a complete system trade-off. Metrics do harm if they cause neglect of other important technical, organizational, or intuitive decision factors. Two metrics have damaged space life support, closure and Equivalent Systems Mass (ESM). Closure measures the fraction of the required system inputs that are produced by recycling system outputs. Increasing closure produces diminishing returns and becomes increasingly expensive. Increasing closure does not directly contribute to providing better life support. ESM measures the total launch mass required to provide life support. ESM includes the mass of the system hardware and of its power, cooling, pressurized volume, spares, and logistics. ESM predicts launch costs, but recently launch costs have been reduced by a factor of 20 or more. System development cost for space hardware is often much greater than launch cost. The past nearly exclusive use of ESM has led to the neglect of Life Cycle Cost (LCC), reliability, cost, and the other engineering factors. Closure and ESM have misguided space life support technology selection for more than twenty years and have adversely affected the expenditure of 100’s of millions of dollars. Metrics can be effectively used three ways in space life support technology selection: 1. A small set of key engineering metrics for preliminary screening. 2. A full set of engineering to guide technical selection. 3. Combining engineering metrics with organizational, political, and intuitive decision factors to understand technology selection. The past emphasis on closure and ESM served to support recycling life support over resupply and built on the intuitive appeal of a human ecosystem in space.

Harry W Jones↗

NASA NTRSDate not supplied

In Vitro Selections with RNAs of Variable Length Converge on a Robust Catalytic Core

In vitro selection is a powerful tool that can be used to understand basic principles of molecular evolution. We used in vitro selection to understand how changes in length and the accumulation of point mutations enable the evolution of functional RNAs. Using RNA populations of various lengths, we performed a series of in vitro experiments to select for ribozymes with RNA ligase activity. We identified a core ribozyme structure that was robust to changes in RNA length, high levels of mutagenesis, and increased selection pressure. Elaboration on this core structure resulted in improved activity which we show is consistent with a larger trend among functional RNAs in which increasing motif size can lead to an exponential improvement in fitness. We conclude that elaboration on conserved core structures is a preferred mechanism in RNA evolution. This conclusion, drawn from selections of RNAs from random sequences, is consistent with proposed evolutionary histories of specific biological RNAs. More generally, our results indicate that modern RNA structures can be used to infer ancestral structures. Our observations also suggest a mechanism by which structural outcomes of early RNA evolution would be largely reproducible even though RNA fitness landscapes consist of disconnected clusters of functional sequences.

In vitro evolution↗

NASA NTRS2022

Automatic variable selection in ecological niche modeling: A case study using Cassin’s Sparrow (Peucaea cassinii)

MERRA/Max provides a feature selection approach to dimensionality reduction that enables direct use of global climate model outputs in ecological niche modeling. The system accomplishes this reduction through a Monte Carlo optimization in which many independent MaxEnt runs, operating on a species occurrence file and a small set of randomly selected variables in a large collection of variables, converge on an estimate of the top contributing predictors in the larger collection. These top predictors can be viewed as potential candidates in the variable selection step of the ecological niche modeling process. MERRA/Max’s Monte Carlo algorithm operates on files stored in the underlying filesystem, making it scalable to large data sets. Its software components can run as parallel processes in a high-performance cloud computing environment to yield near real-time performance. In tests using Cassin’s Sparrow (Peucaea cassinii) as the target species, MERRA/Max selected a set of predictors from Worldclim’s Bioclim collection of 19 environmental variables that have been shown to be important determinants of the species’ bioclimatic niche. It also selected biologically and ecologically plausible predictors from a more diverse set of 86 environmental variables derived from NASA’s Modern-Era Retrospective Analysis for Research and Applications Version 2 (MERRA-2) reanalysis, an output product of the Goddard Earth Observing System Version 5 (GEOS-5) modeling system. We believe these results point to a technological approach that could expand the use global climate model outputs in ecological niche modeling, foster exploratory experimentation with otherwise difficult-to-use climate data sets, streamline the modeling process, and, eventually, enable automated bioclimatic modeling as a practical, readily accessible, low-cost, commercial cloud service.

John L. Schnase↗

NASA NTRS1993

Component Selection, Accelerated Testing, and Improved Modeling of AMTEC Systems for Space Power

Alkali metal thermal to electric converter (AMTEC) designs for space power are numerous, but the selection of materials for construction of long-lived AMTEC devices has been limited to electrodes, current collectors, and the solid electrolyte. AMTEC devices with lifetimes greater than 5 years require careful selection and life testing of all hot-side components. The likely selection of a remote condensed design for initial flight test and probable use with a radioisotope heat source in AMTEC powered planet probes requires the device to be constructed to tolerate operating T greater than 1150K, as well as exposure to Na (g) , and Na (liq) on the high pressure side. The temperatures involved make the characterization of high strength and chemical resistance to Na containing Na 2 O critical. Selection among materials which can be worked should not be driven by ease of fabricablity, as high temperature stability is the critical issue. These concepts drive the selecton of Mo alloys for Na (liq) containment in AMTEC cells for T to 1150K operation, as they are significantly stronger than comparable Nb or Ta alloys, are less soluble in Na (liq) containing dissolved Na 2 O, are workable compared with W alloys (which might be used for certain components), and are ductile at the T greater than 500K of proposed AMTEC modules in space applications.

AMTEC↗

NASA NTRSDate not supplied

Linear Regression Model for Predictive Service Provider Selection

The increasing number of satellites in orbit has led to a growing reliance on third-party service providers for data transfer between Earth and space. Traditional approaches to managing satellite communications require human intervention, which becomes more burdensome with the escalating number of satellites. This research addresses the need for an efficient and automated system to optimize service provider selection for NASA space communication. Previous research has utilized human-operated approaches for service provider management. Our study fills a gap by developing a cognitive algorithm that automates and optimizes the selection process based on various parameters, such as data volume, priority, quality of service and cost. This novel solution reduces user burden, facilitates service management, and contributes to the development of cognitive spaceflight missions, ultimately supporting NASA’s research into Cognitive Communications technology. The algorithm design consists of three major steps: modeling data, developing a Link Selection Algorithm (LSA) based on a grading system, and applying machine learning using linear regression. The LSA evaluates providers based on user-defined constraints, considering factors such as delivery time, cost, and quality of service. We define a suitability metric which allows our algorithm to make a recommendation to a user regarding which commercial service providers to select. The addition of Linear Regression predicts the future suitability value. Our main findings demonstrate that the resulting algorithm can autonomously manage connections between satellites and providers, maximizing communication channel efficiency. This research has significant implications, as it not only addresses a pressing issue in satellite communication management but also advances the field of cognitive spaceflight missions.

Linear regression↗

NASA NTRS1971

Development of lightweight graphite/polyimide honeycomb. Phase 1: Materials selection

The materials selected for the production of extremely lightweight honeycomb sandwich panels are discussed. The resin selected for the first core and face sheet fabrication was Monsanto RS6234 polyimide. The fiber selected for core manufacture was Hercules HT-S, and for face sheets, Hercules HM-S; these selections are discussed.

Poesch, J. G.↗

NASA NTRS1973

Application of composites to the selective reinforcement of metallic aerospace structures

The use of composite materials to selectively reinforce metallic structures provides a low-cost way to reduce weight and a means of minimizing the risks usually associated with the introduction of new materials. An overview is presented of the NASA Langley Research Center programs to identify the advantages and to develop the potential of the selective reinforcement approach to the use of composites. These programs have shown that selective reinforcement provides excellent strength and stiffness improvements to metallic structures. Significant weight savings can be obtained in a cost effective manner. Flight service programs which have been initiated to validate further the merits of selective reinforcement are described.

Brooks, W. A., Jr.↗

NASA NTRS1972

Application of composites to the selective reinforcement of metallic aerospace structures

Brooks, W. A., Jr.↗

NASA NTRS1983

Advanced Platform Systems Technology study. Volume 2: Trade study and technology selection

Three primary tasks were identified which include task 1-trade studies, task 2-trade study comparison and technology selection, and task 3-technology definition. Task 1 general objectives were to identify candidate technology trade areas, determine which areas have the highest potential payoff, define specific trades within the high payoff areas, and perform the trade studies. In order to satisfy these objectives, a structured, organized approach was employed. Candidate technology areas and specific trades were screened using consistent selection criteria and considering possible interrelationships. A data base comprising both manned and unmanned space platform documentation was used as a source of system and subsystem requirements. When requirements were not stated in the data base documentation, assumptions were made and recorded where necessary to characterize a particular spacecraft system. The requirements and assumptions were used together with the selection criteria to establish technology advancement goals and select trade studies. While both manned and unmanned platform data were used, the study was focused on the concept of an early manned space station.

Source record↗

NASA NTRS1984

Tunable mode and line selection by injection in a TEA CO2 laser

Tunable mode selection by injection in pulsed CO2 lasers is examined, and both analytical and numerical models are used to compute the required injection power for a variety of experimental cases. These are treated in two categories: mode selection at a desired frequency displacement from the center frequency of a transition line in a dispersive cavity and mode (and line) selection at the center frequency of a selected transition line in a nondispersive cavity. The results point out the potential flexibility of pulsed injection in providing wavelength tunable high-energy single-frequency pulses.

Menzies, R. T.↗

NASA NTRS1985

A methodology for the selection of frequencies for deep space telecommunications

For each new deep-space mission it is necessary to select the radio frequencies that will be used for uplink and downlink communication. The frequency selection has the objective of avoiding or minimizing the possibility of radio interference between existing and planned missions. This paper presents a comprehensive procedure for the selection of frequencies for deep-space communications. The procedure includes the possible effects of several existing missions on a new mission. This is shown through an example of frequency selection of a new National Aeronautics and Space Administration (NASA) deep-spce mission using actual mission data.

Mathur, A.↗

NASA NTRS1986

X-ray properties of optically selected QSOs

The dependence of the X-ray-to-optical luminosity ratio on optical luminosity and redshift for optically selected QSOs is studied, largely on the basis of two, complete, magnitude-limited samples (Bright Quasar Survey /1983/ and Braccesi Faint /1984/) which were observed with the Einstein Observatory. Heterogeneous samples are established as adequate for the study of that dependence. Optimal choices for increasing the size of the data set for such a study are pointed out. The previous results of Avni and Tananbaum for alpha sub 0, x(z, L sub opt) are confirmed and strengthened, and the numerical sensitivity to changes in the values of q sub 0 and of the optical spectral index is evaluated. It is shown that the large majority, probably all, of optically selected QSOs are X-ray loud; no more than a few percent can be X-ray quiet. Thus X-ray emission appears to be a universal property of QSOs. It is shown that comparisons of optically selected QSOs with X-ray selected QSOs are numerically sensitive to the details of the input ingredients. A residual discrepancy of about a factor of 2 between calculated and observed X-ray number counts is found. Directions for further research that are important for understanding the full bivariate optical-X-ray evolution and luminosity function for QSOs are discussed.

Avni, Y.↗

NASA NTRS1987

Role of orientation reference selection in motion sickness

The objectives of this proposal were developed to further explore and quantify the orientation reference selection abilities of subjects and the relation, if any, between motion sickness and orientation reference selection. The overall objectives of this proposal are to determine (1) if motion sickness susceptibility is related to sensory orientation reference selection abilities of subjects, (2) if abnormal vertical canal-otolith function is the source of these abnormal posture control strategies and if it can be quantified by vestibular and oculomotor reflex measurements, and (3) if quantifiable measures of perception of vestibular and visual motion cues can be related to motion sickness susceptibility and to orientation reference selection ability demonstrated by tests which systematically control the sensory imformation available for orientation.

Peterka, Robert J.↗

NASA NTRS1988

Faint blue objects at high Galactic latitude. V - Palomar Schmidt field centered on selected area 71

Starlike objects with both blue and ultraviolet excess have been selected from a Palomar 1.2 m Schmidt field centered on Kapteyn selected area 71. The method of selection is that used in the previous papers of this series, but modified to account for the differential reddening that occurs across the field. The color classes, color subclasses, positions, and magnitudes of the selected objects are listed.

Usher, Peter D.↗

NASA NTRS1988

Mining for helium: Site selection and evaluation

Part of the University of Wisconsin study of the feasibility of recovering He-3 from the moon is selection and evaluation of potential mining sites. Selection and evaluation are based primarily on salient findings by investigators: (1) Regoliths from areas underlain by highland materials contain less than 20 wppm He; (2) Regoliths of certain maria or parts of maria also contain less than 20 wppm He, but mare regoliths at the Apollo 11 and 17 sites contain 25 to 49 wppm He; (3) The helium content of a regolith is a function of its composition; and (4) Helium is concentrated in the -50 micron size fractions of regoliths. In site selection, the concern is with the compositions of lunar regoliths, in particular with their titanium contents. It is widely accepted that compositions of mare regoliths are controlled by the nature of the underlying basalts from which the regoliths are largely derived. The distribution and extent of the three groups of basalts and the regoliths derived from them are the first basis for site selection and evaluation. Other considerations are briefly discussed.

Cameron, Eugene N.↗

NASA NTRS1989

An evaluation of selected NASA scientific and technical information products: Results of a pilot study

A pilot study was conducted to evaluate selected NASA scientific and technical information (STI) products. The study, which utilized survey research in the form of a self-administered mail questionnaire, had a two-fold purpose -- to gather baseline data regarding the use and perceived usefulness of selected NASA STI products and to develop/validate questions that could be used in a future study concerned with the role of the U.S. government technical report in aeronautics. The sample frame consisted of 25,000 members of the American Institute of Aeronautics and Astronautics in the U.S. with academic, government or industrial affiliation. Simple random sampling was used to select 2000 individuals to participate in the study. Three hundred fifty-three usable questionnaires (17 percent response rate) were received by the established cutoff date. The findings indicate that: (1) NASA STI is used and is generally perceived as being important; (2) the use rate for NASA-authored conference/meeting papers, journal articles, and technical reports is fairly uniform; (3) a considerable number of respondents are unfamiliar with STAR (Scientific and Technical Aerospace Reports), IAA (International Aerospace Abstracts), SCAN (Selected Current Aerospace Notices), and the RECON on-line retrieval system; (4) a considerable number of respondents who are familiar with these media do not use them; and (5) the perceived quality of NASA-authored journal articles and technical reports is very good.

Pinelli, Thomas E.↗