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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 91 records · Page 5
All sourcesNASA NTRSDOE OSTI
NASA NTRS1976

Use of calibration maneuvers for improved performance of strapdown attitude reference systems

Conventional strapdown configurations require precise knowledge of the orientation of the gyro input axes as well as a moderately large, fast computer to provide inertial attitude. This paper presents the mechanization and discusses the operation and performance of an omnidirectional, strapdown pointing control system called All Sky Pointer which does not require precise gyro alignment or a sophisticated computer. Errors caused by gyro-optical sensor misalignment, gyro-integrator bias, and scale factor error are compensated for by the use of calibration maneuvers. Control and computation are provided by an electronics package utilizing technology similar to that found in hand-held calculators. Simulation results indicate that sub arc-minute pointing performance is possible and pointing errors are reduced by as much as an order of magnitude compared with uncompensated systems.

Lorell, K. R.↗
NASA NTRS1976

Experiment S-213 selenocentric geodetic reference system

Development and implementation of a photogrammetric system was undertaken to provide accurate selenodetic positions and topographic mapping of all areas overflown by orbital spacecraft. The system was installed in the scientific instrument module (SIM) bay of the Apollo command service module (CSM). In theory, this system provided everything a photogrammetrist could want: the position of each exposure station would be obtained from Earth-based tracking; the orientation of each photograph could be computed from the synchronized stellar exposure and the lock-angles determined by preflight calibration; and the scale of each stereomodel would be obtained directly from the altimeter data. Operationally, the data acquisition was adequate, but less than optimum. Systematic errors are believed to be the result of the primitive orbit determination procedures in use at the time of the Apollo 15 mission, inadequate models of the lunar gravity field, and spacecraft oscillations induced by uncoupled thrusting and various activities of the astronauts.

Doyle, F. J.↗
NASA NTRS1977

Flight-control/navigation inertial reference system

The preliminary design of a redundant strapdown navigation system for integrated flight-control/navigation use has been completed. Based on application of tuned-gimbal gyros, a compact configuration (13 in x 13 in x 14 in) has been achieved for fail-operational/fail-operational redundancy. Test data are presented for strapdown system test programs including flight testing of the LN-50 tuned-gimbal gyro system. Testing of a redundant sensor configuration is currently in process. Strapdown gyro development also includes ring laser and nuclear magnetic resonance techniques.

Ebner, R. E.↗
NASA NTRS1980

NASA's 25 kW Power Module - Reference System

The paper deals with a 25-kW orbit-based power system which will be used to expand the Shuttle/Spacelab mission durations in a sortie mode and as an orbit-based platform for spacecraft in a free-flying mode. Consideration is given to operations, system description, capabilities and resources, and growth potential.

Powell, L. E.↗
NASA NTRS1980

Reference System Description

Several candidate antenna configurations are evaluated in terms of weight, efficiency, and structural rigidity. Particular emphasis is given to the waveguide slot array and its application to solar power satellites SPS. The electronic aspects of an SPS specific waveguide slot array are defined.

Lunden, C. D.↗
NASA NTRS1980

SPS silicon reference system

The design analysis of a silicon power conversion system for the solar power satellite (SPS) is summarized. The solar array, consisting of glass encapsulated 50 micrometer silicon solar cells, is described. The general scheme for power distribution to the array/antenna interface is described. Degradation by proton irradiation is considered. The interface between the solar array and the klystron equipped power transmitter is described.

Woodcock, G. R.↗
NASA NTRS1982

Feasibility evaluation and study of adapting the attitude reference system to the Orbiter camera payload system's large format camera

A design concept that will implement a mapping capability for the Orbital Camera Payload System (OCPS) when ground control points are not available is discussed. Through the use of stellar imagery collected by a pair of cameras whose optical axis are structurally related to the large format camera optical axis, such pointing information is made available.

Source record↗
NASA NTRS1983

Protoptype integrated design (Pride) system reference manual. Volume 2: Schema definition

An initial description of an evolving relational database schema is presented for the management of finite element model design and analysis data. The report presents a description of each relation including attribute names, data types, and definitions. The format of this report is such that future modifications and enhancements may be easily incorporated.

Fishwick, P. A.↗
NASA NTRS1992

A global mean sea surface based upon GEOS 3 and Seasat altimeter data

A mean sea surface relative to the International Union of Geodesy 1980 Geodetic Reference System reference ellipsoid has been derived from Seasat and GEOS 3 altimeter measurements. This surface, called MSS-9012, has been computed on a grid of 1/8 deg resolution. The surface covers the global ocean between 70 deg N and 72 deg S. Comparisons are made between MSS-9012 and ocean bathymetry. The eastern extent of the Chain Fracture Zone in the Gulf of Guinea is more apparent in the altimetry than in the bathymetry data, as are many other features. The combination of data from the two satellites has successfully retrieved more information about the sea surface than was previously possible using only Seasat data.

Marsh, J. G.↗
NASA NTRSDate not supplied

Reference Intercalibration for the Climate Observing System

Reference Intercalibration is critical in supporting the construction of climate data records, which, given their necessary longevity, must consist of measurements from multiple instruments. Reference intercalibration enables placing multiple instruments on the same radiometric scale, reducing calibration-based biases in climate data records. Measurements that have characteristics of a climate benchmark make excellent in-orbit intercalibration references. Climate Absolute Radiance and Refractivity Observatory (CLARREO) Pathfinder (CPF) consists of a reflected solar (RS) spectrometer (350-2300 nm) that will take hyperspectral Earth reflectance measurements with unprecedented SI-traceable accuracy (0.3%, 1-sigma) from the International Space Station (ISS). CPF measurements will have several characteristics of climate benchmark measurements and will demonstrate its capability as a rigorous in-orbit intercalibration reference with Clouds and Earth’s Radiant Energy System (CERES) and Visible Infrared Imaging Radiometer Suite (VIIRS). The methodologies that have been developed to support CPF-CERES and CPF-VIIRS intercalibration can readily be extended to other Low Earth Orbit and Geostationary instrument targets. With its highly accurate hyperspectral observations, CPF measurements can also be used to improve the characterization of targets widely used for satellite instrument vicarious calibration including Earth land surface pseudo-invariant calibration sites, deep convective clouds, and the Moon. We will discuss the importance of climate benchmark measurement attributes for intercalibration and considerations for the associated intercalibration data analysis to support building and maintaining climate data records.

Yolanda Shea↗
DOE OSTI2014

Communication: Orientational self-ordering of spin-labeled cholesterol analogs in lipid bilayers in diluted conditions

Lipid-cholesterol interactions are responsible for different properties of biological membranes including those determining formation in the membrane of spatial inhomogeneities (lipid rafts). To get new information on these interactions, electron spin echo (ESE) spectroscopy, which is a pulsed version of electron paramagnetic resonance (EPR), was applied to study 3β-doxyl-5α-cholestane (DCh), a spin-labeled analog of cholesterol, in phospholipid bilayer consisted of equimolecular mixture of 1,2-dipalmitoyl-sn-glycero-3-phosphocholine and 1,2-dioleoyl-sn-glycero-3-phosphocholine. DCh concentration in the bilayer was between 0.1 mol.% and 4 mol.%. For comparison, a reference system containing a spin-labeled 5-doxyl-stearic acid (5-DSA) instead of DCh was studied as well. The effects of “instantaneous diffusion” in ESE decay and in echo-detected (ED) EPR spectra were explored for both systems. The reference system showed good agreement with the theoretical prediction for the model of spin labels of randomly distributed orientations, but the DCh system demonstrated remarkably smaller effects. The results were explained by assuming that neighboring DCh molecules are oriented in a correlative way. However, this correlation does not imply the formation of clusters of cholesterol molecules, because conventional continuous wave EPR spectra did not show the typical broadening due to aggregation of spin labels and the observed ESE decay was not faster than in the reference system. So the obtained data evidence that cholesterol molecules at low concentrations in biological membranes can interact via large distances of several nanometers which results in their orientational self-ordering.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗