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NASA NTRSDate not supplied

Multi-Decadal Nitrogen Dioxide and Derived Products from Satellites (MINDS) Datasets Released by NASA GES DISC and Their Applications for Air Quality

Nitrogen dioxide (NO2), a pervasive air pollutant, comes from vehicles, power plants, industrial emissions, and off-road sources such as construction or lawn and gardening equipment. The NASA Goddard Earth Sciences Data and Information Services Center (GES DISC) curates many remote sensing datasets with NO2 retrievals, which have been utilized for air quality research and applications. The remotely-sensed datasets include those generated by the Ozone Monitoring Instrument (OMI) on the Aura satellite, the TROPOspheric Monitoring Instrument (TROPOMI) onboard the Copernicus Sentinel-5 Precursor (S5P), and the Ozone Mapping and Profiling Suite (OMPS) Nadir-Mapper (NM) instrument on the Suomi National Polar-orbiting Partnership (S- NPP). In collaboration with the NASA Making Earth System Data Records for Use in Research Environments (MEaSUREs) Multi-Decadal Nitrogen Dioxide and Derived Products from Satellites (MINDS) project, the GES DISC recently released MINDS datasets. The NASA MEaSUREs MINDS project aims to develop long-term NO2 global data records by adapting a consistent retrieval algorithm to multiple instrument measurements. Long-term data records will be achieved by applying consistent retrieval approaches to multiple satellite instruments, including OMI (2004 - ); the Global Ozone Monitoring Experiment (GOME, 1995-2011) onboard the second European Remote Sensing satellite (ERS-2); the Scanning Imaging Spectrometer for Atmospheric Cartography (SCIAMACHY, 2002-2012) onboard the ENVIronmental SATellite (ENVISAT); GOME-2 on the Meteorological Operational satellites (MetOp-A and MetOp-B, 2006 - ); and TROPOMI onboard the Copernicus S5P (2017 - ). The long-term record (1995 to present) of MINDS datasets makes them very useful for air quality trend studies. Some MINDS datasets with high spatial resolution of only a few kilometers can be used for air quality research and applications at regional scales. In this presentation, we will introduce all of the MINDS products and services, and demonstrate use cases of MINDS data for studying air quality. We will also present a few other NO2 datasets acquired from NASA’s Health and Air Quality Applied Sciences Team (HAQAST), to be archived and distributed by the GES DISC, and highlight some of their applications for air quality and health.

Feng Ding↗
NASA NTRS2012

Investigation of a Moire Based Crack Detection Technique for Propulsion Health Monitoring

The development of techniques for the health monitoring of the rotating components in gas turbine engines is of major interest to NASA s Aviation Safety Program. As part of this on-going effort several experiments utilizing a novel optical Moir based concept along with external blade tip clearance and shaft displacement instrumentation were conducted on a simulated turbine engine disk as a means of demonstrating a potential optical crack detection technique. A Moir pattern results from the overlap of two repetitive patterns with slightly different periods. With this technique, it is possible to detect very small differences in spacing and hence radial growth in a rotating disk due to a flaw such as a crack. The experiment involved etching a circular reference pattern on a subscale engine disk that had a 50.8 mm (2 in.) long notch machined into it to simulate a crack. The disk was operated at speeds up to 12 000 rpm and the Moir pattern due to the shift with respect to the reference pattern was monitored as a means of detecting the radial growth of the disk due to the defect. In addition, blade displacement data were acquired using external blade tip clearance and shaft displacement sensors as a means of confirming the data obtained from the optical technique. The results of the crack detection experiments and its associated analysis are presented in this paper.

Woike, Mark R.↗
NASA NTRS1973

Chemical pump study for Pioneer Venus program

Two chemical pumps were designed for the Pioneer Venus large probe mass spectrometer. Factors involved in the design selection are reviewed. One pump is designed to process a sample of the Venus atmosphere to remove the major component, carbon dioxide, so that the minor, inert components may be measured with greater sensitivity. The other pump is designed to promote flow of atmospheric gas through a pressure reduction inlet system. This pump, located downstream from the mass spectrometer sampling point, provides the pressure differential required for flow through the inlet system. Both pumps utilize the reaction of carbon dioxide with lithium hydroxide. The available data for this reaction was reviewed with respect to the proposed applications, and certain deficiencies in reaction rate data at higher carbon dioxide pressures noted. The chemical pump designed for the inert gas experiment has an estimated volume of 30 cu cm and weight of 80 grams, exclusive of the four valves required for the operation. The chemical pump for the pressure reduction inlet system is designed for a total sample of 0.3 bar liter during the Venus descent.

Rotheram, M.↗
NASA NTRS1972

ATS-F COMSAT millimeter wave propagation experiment.

Description of the transmitting and receiving system configurations to be used in an ATS-F propagation experiment designed to gather data on the attenuation of satellite uplink signals (at approximately 13.2 and 17.8 GHz) due to atmospheric hydrometeors (mostly rain). The data will be used for statistical determination of system power margins required for operational communications systems at frequencies above 10 GHz. A secondary analysis will study site diversity as a means of reducing the required system margins. A spacecraft transponder receives signals from 15 dual-frequency ground transmitter stations and retransmits these signals to a central ground receiving terminal at a frequency of 4 GHz.

Levatich, J. L.↗
NASA NTRS1977

Thermodynamic data report for the Titan/Centaur TC-5 extended mission

The Titan/Centaur vehicle, with the Helios B spacecraft, was launched on January 15, 1976. After the spacecraft was placed into its desired heliocentric trajectory, the Centaur vehicle continued into an extended mission to perform experiments demonstrating increased operational capabilities. The thermal performance of all pertinent Centaur systems and components was evaluated and its capability for satisfactory operation for long duration space coasts was verified. The selected thermal control techniques maintained the Centaur component temperatures within their qualification limits for the entire 8-hour and 22-minute duration of the extended mission.

Lacovic, R. F.↗
NASA NTRS1979

Timing and frequency considerations in the worldwide testing of a spread spectrum communication system

During 1978 and 1979, an Air Force C-135 test aircraft was flown to various locations in the North and South Atlantic and Pacific Oceans for satellite communications experiments. A part of the equipment tested on the aircraft was the SEACOM spread spectrum modem. The SEACOM modem operated at X band frequency from the aircraft via the DSCS II satellite to a ground station. For data to be phased successfully, it was necessary to maintain independent time and frequency accuracy over relatively long periods of time (up to two weeks) on the aircraft and at the ground station. To achieve this goal, two Efratom atomic frequency standards were used. The performance of these frequency standards as used in the spread spectrum modem is discussed, including the effects of high relative velocity, synchronization and the effects of the frequency standards on data performance is discussed. The aircraft environment, which includes extremes of temperature, as well as long periods of shutdown followed by rapid warmup requirements, is also discussed.

Woodring, D. G.↗
NASA NTRS1984

The embedded operating system project

This progress report describes research towards the design and construction of embedded operating systems for real-time advanced aerospace applications. The applications concerned require reliable operating system support that must accommodate networks of computers. The report addresses the problems of constructing such operating systems, the communications media, reconfiguration, consistency and recovery in a distributed system, and the issues of realtime processing. A discussion is included on suitable theoretical foundations for the use of atomic actions to support fault tolerance and data consistency in real-time object-based systems. In particular, this report addresses: atomic actions, fault tolerance, operating system structure, program development, reliability and availability, and networking issues. This document reports the status of various experiments designed and conducted to investigate embedded operating system design issues.

Campbell, R. H.↗
NASA NTRS1984

SMP: A solid modeling program

A prototype solid modeling program, SMP, developed by CSC for Langley Research Center (LaRC) is documented in this paper. The SMP software is employed by the System and Experiments Branch (SEB) of the Space Systems Division (SSD) for preliminary space station design, but is intended as a general purpose tool. The SMP document provides details concerning: the basic geometric modeling primitives and associated operators, the data representation scheme utilized to structure the geometric model, the available commands for both editing and displaying the solid model, the interactive user interface and the input/output interfaces to external software, and the utility of the package in the LaRC computing environment. The document is sufficiently detailed to serve both as a user's guide and reference manual.

Randall, D. P.↗
NASA NTRS1984

Ultrareliable fault-tolerant control systems

It is demonstrated that fault-tolerant computer systems, such as on the Shuttles, based on redundant, independent operation are a viable alternative in fault tolerant system designs. The ultrareliable fault-tolerant control system (UFTCS) was developed and tested in laboratory simulations of an UH-1H helicopter. UFTCS includes asymptotically stable independent control elements in a parallel, cross-linked system environment. Static redundancy provides the fault tolerance. A polling is performed among the computers, with results allowing for time-delay channel variations with tight bounds. When compared with the laboratory and actual flight data for the helicopter, the probability of a fault was, for the first 10 hr of flight given a quintuple computer redundancy, found to be 1 in 290 billion. Two weeks of untended Space Station operations would experience a fault probability of 1 in 24 million. Techniques for avoiding channel divergence problems are identified.

Webster, L. D.↗
NASA NTRS1989

Mars 94 Mission: Current plans and science

The Soviet Space Program proposes large-scale investigations of Mars as one of the most important trends for the next 10 to 15 years. The objectives include global studies of the surface of Mars, its atmosphere, and the return of soil samples to Earth. The first stage of the program is to be implemented in the mid-90s. It includes measurements from an orbiter and a balloon in the atmosphere and on the surface from a rover as well. This can be done using the high energy upper stage of the launch vehicle. The payload mass could amount to about 1500 to 1700 kg. The capabilities of the Mars Mission in 1994 are discussed. As presently planned, Mars will be studied concurrently with the following facilities: an orbiter with instruments for remote sensing from a polar orbit; a balloon deployed in the Martian atmosphere; a rover on the surface; a network of smaller stations on the surface; a subsatellite; and a device to return a container with photo films of the Martian surface taken with a super high resolution. If the exploration of Mars with the MARS-94 spacecraft begins late in 1994 the American Mars-Observer will still be functioning in the near-Mars orbit. Thus, joint operation of the two satellites becomes possible providing coordinated exploration, the creation of joint data banks, joint data interpretation, and the development of a joint engineering model of Mars for its further exploration. There is an opportunity for experiments and instrumentation on the Soviet missions that address questions of interest to exobiology. American scientists are invited to participate in the upcoming Soviet missions, and lend expertise to further understanding of the relationship between the physical and chemical evolution of the solar system and the appearance of life.

Mukhin, Lev↗
NASA NTRS1989

A day-to-day comparison study of Seasat scatterometer winds with winds observed from islands in the tropical Pacific

The winds derived from the Seasat-A Satellite Scatterometer (SASS) measurements have been the subject of great interest since the 1978 mission, because of the promise of radically improved wind observations over the world ocean. Due to the early end of the mission, only a few of the planned ground truth validation experiments could be made, and the subsequent lack of sufficient high quality independent wind data for comparison has limited the ability to resolve critical issues regarding the scatterometer's performance and the correct interpretation of its signal. Operational weather observations were made of ocean winds independent of Seasat mission plans during the Seasat mission period; the results are reported of a comparison study using such observations. Previous verification with in situ winds has been primarily in middle latitudes (GOASEX, JASIN, and NDBO buoys); winds observed from nine tropical Pacific islands are compared with nearly contemporaneous measurements taken by SASS during overpasses of the islands.

Davison, Jerry↗
NASA NTRS1992

Operation and performance of the OSSE instrument

The Oriented Scintillation Spectrometer Experiment (OSSE) on the Arthur Holly Compton Gamma Ray Observatory is described. An overview of the operation and control of the instrument is given, together with a discussion of typical observing strategies used with OSSE and basic data types produced by the instrument. Some performance measures for the instrument are presented that were obtained from pre-launch and in-flight data. These include observing statistics, continuum and line sensitivity, and detector effective area and gain stability.

Cameron, R. A.↗
NASA NTRS1992

Advanced ISDN satellite designs and experiments

The research performed by GTE Government Systems and the University of Colorado in support of the NASA Satellite Communications Applications Research (SCAR) Program is summarized. Two levels of research were undertaken. The first dealt with providing interim services Integrated Services Digital Network (ISDN) satellite (ISIS) capabilities that accented basic rate ISDN with a ground control similar to that of the Advanced Communications Technology Satellite (ACTS). The ISIS Network Model development represents satellite systems like the ACTS orbiting switch. The ultimate aim is to move these ACTS ground control functions on-board the next generation of ISDN communications satellite to provide full-service ISDN satellite (FSIS) capabilities. The technical and operational parameters for the advanced ISDN communications satellite design are obtainable from the simulation of ISIS and FSIS engineering software models of the major subsystems of the ISDN communications satellite architecture. Discrete event simulation experiments would generate data for analysis against NASA SCAR performance measure and the data obtained from the ISDN satellite terminal adapter hardware (ISTA) experiments, also developed in the program. The Basic and Option 1 phases of the program are also described and include the following: literature search, traffic mode, network model, scenario specifications, performance measures definitions, hardware experiment design, hardware experiment development, simulator design, and simulator development.

Pepin, Gerard R.↗
NASA NTRS1993

Evaluation of high temperature superconductive thermal bridges for space-borne cryogenic infrared detectors

The focus of this research is on the reduction of the refrigeration requirements for infrared sensors operating in space through the use of high temperature superconductive (HTS) materials as electronic leads between the cooled sensors and the relatively warmer data acquisition components. Specifically, this initial study was directed towards the design of an experiment to quantify the thermal performance of these materials in the space environment. First, an intensive review of relevant literature was undertaken, and then, design requirements were formulated. From this background information, a preliminary experimental design was developed. Additional studies will involve a thermal analysis of the experiment and further modifications of the experimental design.

Scott, Elaine P.↗
NASA NTRS1994

Rotordynamic Instability Problems in High-Performance Turbomachinery, 1993

The first rotordynamics workshop proceedings (NASA CP-2133, 1980) emphasized a feeling of uncertainty in predicting the stability of characteristics of high-performance turbomachinery. In the second workshop proceedings (NASA CP-2250, 1982) these uncertainties were reduced through programs established to systematically resolve problems, with emphasis on experimental validation of the forces that influence rotordynamics. In the third proceedings (NASA CP-2338, 1984) many programs for predicting or measuring forces and force coefficients in high-performance turbomachinery produced results. Data became available for designing new machines with enhanced stability characteristics or for upgrading existing machines. In the fourth proceedings (NASA CP-2443, 1986) there emerged trends toward a more unified view of rotordynamic instability problems and several encouraging new analytical developments. The fifth workshop (NASA CP-3026, 1988) supported the continuing trend toward a unified view with several new developments in the design and manufacture of new turbomachineries with enhanced stability characteristics along with new data and associated numerical/theoretical results. The sixth workshop report (NASA CP-3 I 22, 1990) field experience and experimental results, and expanded the use of computational and control techniques with integration of damper, bearing, and eccentric seal operation results. The present workshop continues to report field experiences, numerical, theoretical, and experimental results and control methods for seals, bearings, and dampers with some attention given to variable thermo physical properties and turbulence measurements, and introduction of two-phase flow results. The intent of the workshop and this proceedings is to provide a continuing impetus for an understanding and resolution of these problems.

Instabilities↗
NASA NTRS1995

Electronic Ambient-Temperature Recorder

Electronic temperature-recording unit stores data in internal memory for later readout. Records temperatures from minus 40 degrees to plus 60 degrees C at intervals ranging from 1.875 to 15 minutes. With all four data channels operating at 1.875-minute intervals, recorder stores at least 10 days' data. For only one channel at 15-minute intervals, capacity extends to up to 342 days' data. Developed for recording temperatures of instruments and life-science experiments on satellites, space shuttle, and high-altitude aircraft. Adaptable to such terrestrial uses as recording temperatures of perishable goods during transportation and of other systems or processes over long times. Can be placed directly in environment to monitor.

Russell, Larry↗
NASA NTRS2001

Wind Tunnel Testing of the NASA-DFRC Flutterometer using a Two DOF Wing Section

Flutter of an aeroelastic structure is potentially destructive aeroelastic instability. This phenomenon has motivated research within the aeroelastic community to develop methods that can accurately predict aeroelastic instabilities. The Flutterometer method used herein, and as developed by NASA DFRC, is based upon the mu method which has been coupled with wavelet filtering processes in estimating aeroelastic models from flight data. The approach leads to a methodology to predict the occurrence of flutter boundaries, and may prove to reliably predict flutter boundaries during flight tests. An analytical model is used as the first estimate of the aeroelastic structural dynamics, and uncertainty operators are introduced into the system to model variations between the theoretical system and the physical system. The modelling uncertainties are then updated from experimental data. Although the model used did not work well with this particular experiment, a sensitivity analysis was additionally performed and improvements suggested.

Strganac, Thomas W.↗
NASA NTRS2007

The Crew Earth Observations Experiment: Earth System Science from the ISS

This viewgraph presentation reviews the use of Astronaut Photography (AP) as taken from the International Space Station (ISS) in Earth System Science (ESS). Included are slides showing basic remote sensing theory, data characteristics of astronaut photography, astronaut training and operations, crew Earth observations group, targeting sites and acquisition, cataloging and database, analysis and applications for ESS, image analysis of particular interest urban areas, megafans, deltas, coral reefs. There are examples of the photographs and the analysis.

Stefanov, William L.↗