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At least 343 records · Page 19
All sourcesNASA NTRSDOE OSTI
NASA NTRS2022

The Psyche Planning Software Subsystem: Creating a Robust Toolset for a Discovery-class Mission

Psyche is a Discovery-class mission to the small metal-rich asteroid (16) Psyche, and is slated to launch in 2022. Psyche, like many missions, requires low-cost activity planning and sequence generation that serves as the backbone to overall uplink design. Such tools must be maintainable over long periods of operations, and powerful enough to solve complex issues that deep-space one-off missions encounter. In this paper we introduce cost-effective solutions that leverage inner- and open-source principles to meet a variety of common and novel use cases.The uplink process that was designed to meet these challenges is presented, as well as the data-flow through the high-level architecture of the planning software subsystem. The user-facing planning tools are described, particularly the Science Opportunity Analyzer, the Plan Editor, Psyche’s planning automation in the Blackbird framework, and Psyche Simulation Reports. All these applications are either new or have been substantially revamped to meet Psyche’s concept of operations. In particular, ensuring the entire toolchain can correctly process epoch-relative activities is discussed. Underlying the main applications are a common set of dependencies developed and maintained by a new cross-mission association of planning developers. In this way, Psyche can inherit well-tested functionality which saves effort and ensures its developers can focus on solving domain challenges. Quality control of the applications and libraries is ensured with a code-review and unit-test based novel ‘CM lite’ process. Collaboration with international industry and academia using the open-source modules is already occurring.The planning and scheduling software is designed to maximize operator awareness of the integrated plan at every step of the process and use common interfaces and file formats to easily transfer information. Design choices plus the team’s test-driven development process enables more expansive capabilities compared to the decentralized planning and sequence generation functions typical of Discovery-class orbiters without significant development cost increases. Benefits and drawbacks of Psyche’s approach are discussed, including comparison to other missions and tools where appropriate.

Ramanathan, Keshav↗
NASA NTRS2002

Relation Between Polar Plumes and Fine Structure in the Solar Wind from Ulysses High-Latitude Observations

Ulysses observations showed that pressure balance structures (PBSs) are a common feature in the high-latitude and high-speed solar winds near the solar minimum. On the other hand, coronal plumes are common in polar coronal holes. PBSs are believed to be remnants of coronal plumes and to be related to network activity such as magnetic reconnection in the photosphere from previous studies. This suggests that information on the magnetic structure of PBSs would help to confirm the relation between PBSs and polar plumes We have investigated the magnetic structures of the PBSs by applying a minimum variance analysis to Ulysses/Magnetometer data and by examining the pitch-angle distribution of energetic electrons measured with Ulysses/SWOOPS. We have found that PBSs have relatively more tangential discontinuities rather than rotational from the minimum variance analysis. Further, most PBSs also show bi-directional electron flux or isotropic pitch-angle distribution or the distribution expected in association with current-sheet structures from the analysis of high-energy electron data. In this, we find further evidence that PBSs are generated due by network activity at the base of polar plumes and their magnetic structures are like current sheets or plasmoids.

Yamauchi, Yohei↗
NASA NTRS2019

Electrodynamic Dust Shield Testing on the Materials on International Space Station Experiment 11

Dust is a major concern for lunar exploration. To combat the effects of dust, NASA, academia, and industry are developingsolutions to the dust problem. One potential technology solution for this problem is the Electrodynamic DustShield (EDS). Many years of research and development have gone into this technology. The Materials on InternationalSpace Station Experiment - 11 (MISSE-11) provides a long term space exposure platform for this technology to verifycompatibility of materials and manufacturing processes to the space environment. The MISSE-11 EDS experimentconsists of 12 EDS panels. These panels are made of glass, polyimide, or prototype spacesuit fabric. Some panels arecovered with a lotus leaf coating while others are covered with thermal paint. They are flown in the wake position ofthe ISS to simulate the lunar environment. Two panels are in an active configuration and are energized with a highvoltage power supply, which generates high-voltage pulses to activate the dust shields. Current and voltage data arerecovered from each of these trials to compare to baseline data. Also, each of the EDS panels are imaged on a monthlybasis to track any changes with time that may occur with the EDS variants. In this paper, we report preliminary dataand analysis from this spaceflight experiment.

Johansen, Michael R.↗
NASA NTRS1996

Preparation of Flight Operations and IWS Integration of the CELIAS Experiment on the SOHO Spacecraft

During this annual progress report time period, the following activities took place: (1) Generation of several versions of the CELIAS (STOF/SEM/CTOF/MTOF/DPU) commissioning timeline for the first 180 days after launch. These were written and submitted by A. Galvin after consultation (phone, fax, e-mail, meetings) with the CELIAS Instrument Manager and Lead-Co-I's. (2) Identification of several problems with the CELIAS portion of the Project Data Base (PDB). (3) Meetings with the Flight Operations Team regarding PDB, critical commands, etc. (4) Attend Science Operations Working Group (SOWG) Meetings (November 1994, February 1995, May 1995) and Flight Operations Review Meeting (July 1995). (5) Participate in Flight Operation Simulations SIM 1 (November 14-18, 1994), SIM 2 (May 1-4, 1995) and SIM3 (August 7-11, 1995). (6) Participate in the Ground System Compatibility Test Rehearsal (April 24- 28, 1995), GSCT #2 (May 30-June 14, 1995), GSCT #3 (September 12-22, 1995), and GSCT #4b (October 30-November 5, 1995). A small portion of the documentation for the above cited activities is appended.

Ipavich, Fred↗
NASA NTRS1994

Active control of turbomachine discrete tones

This paper was directed at active control of discrete frequency noise generated by subsonic blade rows through cancellation of the blade row interaction generated propagating acoustic waves. First discrete frequency noise generated by a rotor and stator in a duct was analyzed to determine the propagating acoustic pressure waves. Then a mathematical model was developed to analyze and predict the active control of discrete frequency noise generated by subsonic blade rows through cancellation of the propagating acoustic waves, accomplished by utilizing oscillating airfoil surfaces to generate additional control propagating pressure waves. These control waves interact with the propagating acoustic waves, thereby, in principle, canceling the acoustic waves and thus, the far field discrete frequency tones. This model was then applied to a fan exit guide vane to investigate active airfoil surface techniques for control of the propagating acoustic waves, and thus the far field discrete frequency tones, generated by blade row interactions.

Fleeter, Sanford↗
NASA NTRS2002

Development of Closed-Loop Simulation Methods for a Next-Generation Terminal Area Automation System

A next-generation air traffic decision support tool, known as the Active Final Approach Spacing Tool (aFAST), will generate heading, speed and altitude commands to achieve more precise separation of aircraft in the terminal area. The techniques used to analyze the performance of earlier generation decision support tools are not adequate to analyze the performance of aFAST. This paper summarizes the development of a new and innovative fully closed-loop testing method for aFAST. This method, called trajectory feedback testing, closes each aircraft's control loop inside of the aFAST scheduling algorithm. Validation of trajectory feedback testing by examination of the variation of aircraft time-of-arrival predictions between schedule updates and the variation of aircraft excess separation distances between simulation runs is presented.

Robinson, John E., III↗
NASA NTRS2014

The Sunspot Record: 1826-1980

The International Sunspot Number is used as a measure of the level of solar activity in many important studies. This includes studies of the effects of solar activity on climate change and on the generation of radioisotopes used to infer levels of solar activity going back thousands of years. Any systematic errors in the historical record of the sunspot number can profoundly alter the conclusions of these studies. There is substantial evidence that the currently accepted International Sunspot Numbers have been subjected to changes in the way the numbers are calculated and to changes in the weights given to observations of various observers. In this talk I will focus on the time period from 1826 to 1980 which covers principal observers Schwabe, Wolf, Wolfer, Brunner, and Waldmeier. Previous investigations have indicated problems associated with Schwabe's observations (1826 to 1867), the first decades of the Greenwich observations (1874 to about 1910), and the introduction of a different counting method by Waldmeier (1946-1980). I will examine the evidence for these problems and the possible solutions that might be used to provide improved estimates of the sunspot numbers and their errors over this time interval.

Hathaway, David H.↗
NASA NTRS1989

Electrocatalysis for oxygen electrodes in fuel cells and water electrolyzers for space applications

In most instances separate electrocatalysts are needed to promote the reduction of O2 in the fuel cell mode and to generate O2 in the energy storage-water electrolysis mode in aqueous electrochemical systems operating at low and moderate temperatures (T greater than or equal to 200 C). Interesting exceptions are the lead and bismuth ruthenate pyrochlores in alkaline electrolytes. These catalysts on high area carbon supports have high catalytic activity for both O2 reduction and generation. Rotating ring-disk electrode measurements provide evidence that the O2 reduction proceeds by a parallel four-electron pathway. The ruthenates can also be used as self-supported catalysts to avoid the problems associated with carbon oxidation, but the electrode performance so far achieved in the research at Case Western Reserve University (CWRU) is considerably less. At the potentials involved in the anodic mode the ruthenate pyrochlores have substantial equilibrium solubility in concentrated alkaline electrolyte. This results in the loss of catalyst into the bulk solution and a decline in catalytic activity. Furthermore, the hydrogen generation counter electrode may become contaminated with reduction products from the pyrochlores (lead, ruthenium).

Prakash, Jai↗
NASA NTRS1989

Electrocatalysts for oxygen electrodes in fuel cells and water electrolyzers for space applications

In most instances separate electrocatalysts are needed to promote the reduction of O2 in the fuel cell mode and to generate O2 in the energy storage-water electrolysis mode in aqueous electrochemical systems operating at low and moderate temperatures (T greater than or equal to 200 C). Interesting exceptions are the lead and bismuth ruthenate pyrochlores in alkaline electrolytes. These catalysts on high area carbon supports have high catalytic activity for both O2 reduction and generation (1,2). Rotating ring-disk electrode measurements provide evidence that the O2 reduction proceeds by a parallel four-electron pathway. The ruthenates can also be used as self-supported catalysts to avoid the problems associated with carbon oxidation, but the electrode performance so far achieved in the research at Case Western Reserve University (CWRU) is considerably less. At the potentials involved in the anodic mode the ruthenate pyrochlores have substantial equilibrium solubility in concentrated alkaline electrolyte. This results in the loss of catalyst into the bulk solution and a decline in catalytic activity. Furthermore, the hydrogen generation counter electrode may become contaminated with reduction products from the pyrochlores (lead, ruthenium). A possible approach to this problem is to immobilize the pyrochlore catalyst within an ionic-conducting solid polymer, which would replace the fluid electrolyte within the porous gas diffusion O2 electrode. For bulk alkaline electrolyte, an anion-exchange polymer is needed with a transference number close to unity for the Oh(-) ion. Preliminary short-term measurements with lead ruthenates using a commercially available partially-fluorinated anion-exchange membrane as an overlayer on the porous gas-fed electrode indicate lower anodic polarization and virtually unchanged cathodic polarization.

Prakash, Jai↗
NASA NTRS1972

Electronic switching circuit uses complementary non-linear components

Inherent switching properties of saturable inductors and storage diodes are combined to perform large variety of electronic functions, such as pulse shaping, gating, and multiplexing. Passive elements replace active switching devices in generation of complex waveforms.

Zucker, O. S.↗
NASA NTRS1973

Research in particles and fields in space

Theoretical and experimental work in charged particle and magnetic field research is reported. Activities center on plasma generation and acceleration, ATS 1 data processing for evaluation of magnetospheric substorms and micropulsations during magnetic disturbances, and the development of solar wind model using Mariner observations.

Coleman, P. J., Jr.↗
NASA NTRS1974

Space processing applications payload equipment study. Volume 1: Executive summary

A study was conducted to derive and collect payload information on the anticipated space processing payload requirements for the Spacelab and space shuttle orbiter planning activities. The six objectives generated by the study are defined. Concepts and requirements for space processing payloads to accommodate the performance of the shuttle-supported research phase are analyzed. Diagrams and tables of data are developed to show the experiments involved, the power requirements, and the payloads for shared missions.

Hammel, R. L.↗
NASA NTRS1975

Elemental composition of suspended particulates as functions of space and time in Cleveland, Ohio

An approach to the analysis of a very large elemental concentration data set. The particular data considered was generated by instrumental neutron activation and emission spectroscopy analyses of over 750 24-hour ambient air particulate samples collected at 16 sites in Cleveland, Ohio, during the 15 months from August 1971 thru October 1972. Examples are presented that show the use of multiple approaches to interpreting the data, including pairwise correlation statistics, selective data plotting and cluster analysis.

Neustadter, H. E.↗
NASA NTRS1979

Mod-1 wind turbine generator analysis and design report, volume 1

The activities leading to the completion of detail design of the MOD-1 wind turbine generator are described. Emphasis is placed on the description of the design as it finally evolved. However, the steps through which the design progressed are also traced in order to understand the major design decisions.

Source record↗
NASA NTRS1980

Analysis of electrical transients created by lightning

A series of flight tests was conducted using a specially-instrumented NASA Learjet to study the electrical transients created on an aircraft by nearby lightning. The instrumentation included provisions for the time-domain and frequency-domain recording of the electrical signals induced in sensors located both on the exterior and on the interior of the aircraft. The design and calibration of the sensors and associated measuring systems is described together with the results of the flight test measurements. The results indicate that the concept of providing instrumentation to follow the lightning signal from propagation field, to aircraft skin current, to current on interior wiring is basically sound. The results of the measurement indicate that the high frequency signals associated with lightning stroke precursor activity are important in generating electromagnetic noise on the interior of the aircraft. Indeed, the signals produced by the precursors are often of higher amplitude and of longer duration that the pulse produced by the main return stroke.

Nanevicz, J. E.↗
NASA NTRS1981

Precursor active galaxies, active galaxies and the X-ray and gamma-ray background

A description is presented of a model in which the X-ray and gamma-ray background can result from the superposition of radiation from active galaxies in different stages of their evolutionary history. This scheme is based on the generalization of a black-hole model developed for gamma-ray production in active galaxies by Leiter (1980). Both thermal and nonthermal accretion disk processes around massive rotating Kerr black holes are considered. Attention is given to cosmological conditions leading to precursor active galaxies (PAG), PAG as origin of the cosmic X-ray background, and the evolution of PAG into Seyfert galaxies as origin of the gamma-ray background. It is found that after spin-up of the central black hole an active galactic nucleus can generate nonthermal radiation very efficiently up to a few MeV.

Leiter, D.↗
NASA NTRS1982

Rotating gravity gradiometer study

Two rotating gravity gradiometer (RGG) sensors, along with all the external electronics needed to operate them, and the fixtures and special test equipment needed to fill and align the bearings, were assembled in a laboratory, and inspected. The thermal noise threshold of the RGG can be lowered by replacing a damping resistor in the first stage electronics by an active artificial resistor that generates less random voltage noise per unit bandwidth than the Johnson noise from the resistor it replaces. The artificial resistor circuit consists of an operational amplifier, three resistors, and a small DC to DC floating power supply. These are small enough to be retrofitted to the present circuit boards inside the RGG rotor in place of the 3 Megohm resistor. Using the artificial resistor, the thermal noise of the RGG-2 sensor can be lowered from 0.3 Eotvos to 0.15 Eotvos for a 10 sec integration time.

Forward, R. L.↗
NASA NTRS1984

Active Sticks: a New Dimension in Controller Design

A smart stick controller was built which actively produces a force to interact with the subject's hand and to aid in tracking. When the human tracks in this situation, the man-machine system can be viewed as the combination of two closed loop feedback paths. The inner loop occurs as a result of a tactile information channel effecting the man-controller interaction through force with this stick in the active mode (the stick generates a force) and the passive mode (the stick not generating a force) are reported. The most noteworthy observation is a significant increase in apparent neuromotor bandwidth and consequently better tracking performance.

Repperger, D. W.↗