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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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NASA NTRS2012

NASA's Next Generation Space Geodesy Program

Requirements for the ITRF have increased dramatically since the 1980s. The most stringent requirement comes from critical sea level monitoring programs: a global accuracy of 1.0 mm, and 0.1mm/yr stability, a factor of 10 to 20 beyond current capability. Other requirements for the ITRF coming from ice mass change, ground motion, and mass transport studies are similar. Current and future satellite missions will have ever-increasing measurement capability and will lead to increasingly sophisticated models of these and other changes in the Earth system. Ground space geodesy networks with enhanced measurement capability will be essential to meeting the ITRF requirements and properly interpreting the satellite data. These networks must be globally distributed and built for longevity, to provide the robust data necessary to generate improved models for proper interpretation of the observed geophysical signals. NASA has embarked on a Space Geodesy Program with a long-range goal to build, deploy and operate a next generation NASA Space Geodetic Network (SGN). The plan is to build integrated, multi-technique next-generation space geodetic observing systems as the core contribution to a global network designed to produce the higher quality data required to maintain the Terrestrial Reference Frame and provide information essential for fully realizing the measurement potential of the current and coming generation of Earth Observing spacecraft. Phase 1 of this project has been funded to (1) Establish and demonstrate a next-generation prototype integrated Space Geodetic Station at Goddard's Geophysical and Astronomical Observatory (GGAO), including next-generation SLR and VLBI systems along with modern GNSS and DORIS; (2) Complete ongoing Network Design Studies that describe the appropriate number and distribution of next-generation Space Geodetic Stations for an improved global network; (3) Upgrade analysis capability to handle the next-generation data; (4) Implement a modern survey system to measure inter-technique vectors for co-location; and (5) Develop an Implementation Plan to build, deploy and operate a next-generation integrated NASA SGN that will serve as NASA's contribution to the international global geodetic network. An envisioned Phase 2 (which is not currently funded) would include the replication of up to ten such stations to be deployed either as integrated units or as a complement to already in-place components provided by other organizations. This talk will give an update on the activities underway and the plans for completion.

Merkowitz, S. M.↗
NASA NTRS2012

NASA's Next Generation Space Geodesy Program

Requirements for the ITRF have increased dramatically since the 1980s. The most stringent requirement comes from critical sea level monitoring programs: a global accuracy of 1.0 mm, and 0.1mm/yr stability, a factor of 10 to 20 beyond current capability. Other requirements for the ITRF coming from ice mass change, ground motion, and mass transport studies are similar. Current and future satellite missions will have ever-increasing measurement capability and will lead to increasingly sophisticated models of these and other changes in the Earth system. Ground space geodesy networks with enhanced measurement capability will be essential to meeting the ITRF requirements and properly interpreting the satellite data. These networks must be globally distributed and built for longevity, to provide the robust data necessary to generate improved models for proper interpretation of the observed geophysical signals. NASA has embarked on a Space Geodesy Program with a long-range goal to build, deploy and operate a next generation NASA Space Geodetic Network (SGN). The plan is to build integrated, multi-technique next-generation space geodetic observing systems as the core contribution to a global network designed to produce the higher quality data required to maintain the Terrestrial Reference Frame and provide information essential for fully realizing the measurement potential of the current and coming generation of Earth Observing spacecraft. Phase 1 of this project has been funded to (1) Establish and demonstrate a next-generation prototype integrated Space Geodetic Station at Goddard s Geophysical and Astronomical Observatory (GGAO), including next-generation SLR and VLBI systems along with modern GNSS and DORIS; (2) Complete ongoing Network Design Studies that describe the appropriate number and distribution of next-generation Space Geodetic Stations for an improved global network; (3) Upgrade analysis capability to handle the next-generation data; (4) Implement a modern survey system to measure inter-technique vectors for co-location; and (5) Develop an Implementation Plan to build, deploy and operate a next-generation integrated NASA SGN that will serve as NASA s contribution to the international global geodetic network. An envisioned Phase 2 (which is not currently funded) would include the replication of up to ten such stations to be deployed either as integrated units or as a complement to already in-place components provided by other organizations. This talk will give an update on the activities underway and the plans for completion.

Pearlman, M. R.↗
NASA NTRS1996

GPS Based Attitude Determination for Spacecraft: System Engineering Design Study and Ground Testbed Results

By differencing carrier phase measurements from multiple antennas, a global positioning systems (GPS) reciever can determine the attitude of a coordinate frame defined by the antenna baselines. This paper examines the potential role of such a capability within spacecraft avionics. The applications served by current GPS capabilities are identified. Architectural options are considered, and a baseline which satisfies the needs of most applications is defined. The majority of this paper then focuses on the prototyping of this baseline architecture within the Jet Propulsion Laboratory's (JPL's) Flight System Testbed (FST). The test setup is described, and test results are presented. The paper closes with an analysis of the limiting factors in the GPS based altitude determination error budget, a forecast of future capabilities, and a discussion of the advances that will be required to achieve those capabilities.

GPS↗
NASA NTRS1990

Results of the users' requirements survey

The objectives of the High Resolution, High Frame Rate Video Technology (HHVT) Users' Requirements Survey were the following: (1) Document the requirements of potential users of the HHVT system; (2) Establish a data base relating key video parameters to HHVT users; (3) Guide the development of a high resolution, high frame rate video system offering high data storage capacity and high data transmission rates; (4) Allow users to compare their requirements to those of other users and to the state-of-the-art technology; and (5) Allow users to reassess, if necessary, their requirements in the light of existing and near-term technology. The results of the Users' Requirements Survey are presented. The diversity of these requirements indicates a need for developing a video system with great flexibility.

Butcher, Robert L.↗
NASA NTRS1988

Few-nanoradian deep space navigation in local reference frames

Angular navigation with Very Long Baseline Interferometry is performed at the 15-100 nanoradian level by differencing the interferometric delays of a spacecraft and nearby radio source. Clock rate, earth orientation and atmospheric effects limit the accuracy. By observing several radio sources along with the spacecraft, these dominant errors can be reduced by parameter estimation. Using improved instrumentation, the technique analyzed below, which can potentially yield 1-3 nanoradian accuracy, locates the spacecraft in a local reference frame of radio sources. In this paper, observation strategies and covariance results will be presented for the local reference frame technique. The error contributions of system noise and tropospheric fluctuations will be evaluated. An application of this few-nanoradian technique to Jovian approach is also presented.

Treuhaft, R. N.↗
NASA NTRS1979

Map characteristics of Landsat mosaics

Map characteristics of the Landsat mosaics developed at JPL are considered. Procedures for digital mosaicking of Landsat frames to standard map projections were used to mosaic at full resolution ten scenes over the California desert region and twenty-one scenes over Arizona. The procedures are analyzed for horizontal positioning error (global and local) and the potential for classification error associated with the adjustment of brightness of Z values between frames; the use of this technology for the mapping of extensive features is discussed. Mosaicking facilities, techniques, mapping accuracy, and thematic mapping characteristics are described. A comparative analysis of Landsat mosaicking technology developed at Goddard Space Flight Center, IBM Gaithersburg, and USGS Flagstaff is made, and suggestions are given for algorithm development to improve systems capacity and ability to handle a variety of cases.

Zobrist, A. L.↗
NASA NTRS1995

Accuracy of wet troposphere radio path delay estimated from infrared emission

Several radio science applications require determination of the excess radio-propagation path delay caused by the Earth's atmosphere. These include very long baseline interferometry, spacecraft tracking, and potentially, detection of gravitational waves utilizing a link to a distant interplanetary spacecraft. At Ka band, the major source of variability of path delay is the fluctuations in the moisture content of the troposphere. The path delay characterization requirements for a planned gravitational wave experiment are novel and challenging. the error contribution to the phase observations due to path delay variation must be reduced by nearly two orders of magnitude over that occurring naturally on time scales of 100 to 10,000 seconds. Current approaches relying on microwave water vapor radiometry with ancillary data can deliver one order of magnitude calibration of these fluctuations, and more advanced systems are under development within the 2001-2002 time frame of the Cassini Mission to Saturn. The current work evaluates the potential for an alternative observational approach, using a ground-based Fourier transform spectrometer.

Parker, J. W.↗
NASA NTRS1972

An interdisciplinary analysis of ERTS data for Colorado mountain environments using ADP techniques. An early analysis of ERTS-1 data

There are no author-identified significant results in this report. The principal problem encountered has been the lack of good quality, small scale baseline photography for the test areas. Analysis of the ERTS-1 data for the San Juan Site will emphasize development of a preliminary spectral classification defining grass cover categories, and then selection of subframes for intensive investigation of the forestry, geologic, and hydrologic properties of the area. Primary work has been devoted to the selection and digitization of areas for topographic modeling, and compilation of ground based data maps necessary for computer analysis. Study effort has emphasized: geomorphic features; macro-vegetation; micro-vegetation; snow-hydrology; insect/disease damage; and blow-down. Analysis of a frame of the Lake Texoma area indicates a great deal of potential in the analysis and interpretation of ERTS imagery. Preliminary results of investigations of geologic, forest, range, cropland, and water resources of the area are summarized.

Hoffer, R. M.↗
NASA NTRS1973

The particle resonance in spiral galaxies - Nonlinear effects.

A theory is developed to account for the nonlinear effects, near the particle resonance, found by numerical integration. There are four equilibrium points in the rotating frame of reference: two of them unstable, at the minima of potential (L1, L2), and two stable, at the maxima of potential (L4, L5). Many particles are trapped in librating orbits around L4, L5. Using the lowest-order terms of a 'third integral' of motion near L4, L5, the behavior of the trapped orbits is determined, and the approximate theoretical results are compared with the orbits found numerically by computer. An estimate of the trapped mass is given. It amounts to about 30% of the total mass between 9 and 11 kpc when the particle resonance is at r sub s = 10 kpc and the maximum force due to the spiral is 4% of the axisymmetric force. Some effects due to these mass concentrations are found numerically and theoretically.

Contopoulos, G.↗
NASA NTRS1982

Seasat synthetic-aperture radar data reduction using parallel programmable array processors

This paper presents a digital processing system that produces the Seasat synthetic-aperture radar (SAR) imagery. The system consists of a SEL 32/77 host minicomputer and three AP-120B array processors. The partitioning of the SAR processing functions and the design of software modules is described. The rationale for selecting the parallel array processor architecture and the methodology for developing the parallel processing scheme on this system is described. This system attains a Seasat SAR data reduction speed of 2.5 h per 25-m resolution 4-look and 100 km x 100 km image frame. A preliminary performance evaluation of this parallel processing system and potential future applications for remote sensing data reduction are described.

Wu, C.↗
NASA NTRS1987

Inverse kinematic-based robot control

A fundamental problem which must be resolved in virtually all non-trivial robotic operations is the well-known inverse kinematic question. More specifically, most of the tasks which robots are called upon to perform are specified in Cartesian (x,y,z) space, such as simple tracking along one or more straight line paths or following a specified surfacer with compliant force sensors and/or visual feedback. In all cases, control is actually implemented through coordinated motion of the various links which comprise the manipulator; i.e., in link space. As a consequence, the control computer of every sophisticated anthropomorphic robot must contain provisions for solving the inverse kinematic problem which, in the case of simple, non-redundant position control, involves the determination of the first three link angles, theta sub 1, theta sub 2, and theta sub 3, which produce a desired wrist origin position P sub xw, P sub yw, and P sub zw at the end of link 3 relative to some fixed base frame. Researchers outline a new inverse kinematic solution and demonstrate its potential via some recent computer simulations. They also compare it to current inverse kinematic methods and outline some of the remaining problems which will be addressed in order to render it fully operational. Also discussed are a number of practical consequences of this technique beyond its obvious use in solving the inverse kinematic question.

Wolovich, W. A.↗
NASA NTRS1992

The Martian dust cycle

Martian dust plays a key role in determining the current climate of Mars, and is suspected of having had a major influence on the evolution of the surface and the history of climatic conditions on the planet. From spacecraft and ground-based observations, some understanding has been acquired of the styles and frequency of dust motion in the atmosphere and at the surface, of atmospheric dust loading, dust particle properties, and their variability. Limited constraints have also been derived for the volumes and ages of some potential dust reservoirs on the surface. These data are adequate to frame questions about the seasonal and long-term cycles of dust of Mars. Additional data are needed to place quantitative constraints on components of these cycles, on their possible linkage to one another, and to draw conclusions from the dust budget about the climate history of Mars.

Kahn, R. A.↗
NASA NTRS1994

Toward astrometric tracking with the infrared spatial interferometer

Infrared interferometric demonstrations with the University of California, Berkeley's infrared spatial interferometer (ISI) on Mt. Wilson explore the potential of infrared and optical astrometry for deep space tracking, reference frame development, and DSN science. Astrometric data taken and analyzed over the last five years from the ISI have shown that instrumental and atmospheric effects limit current demonstrations. The benefits of sensitivity upgrades, which were performed in 1991 and 1992, have been demonstrated by comparing point-to-point phase fluctuations for the fall 1989 and fall 1992 observing epochs. This comparison showed that point-to-point phase fluctuations due to tropospheric and quantum noise, for optimal integration times of 0.2 sec, are approaching the 0.1-cycle level needed to reliably connect the interferometric phase. The increase in sensitivity, coupled with that arising from very recent hardware upgrades, will greatly enhance phase-connection capabilities necessary for astrometry in the presence of atmospheric refractivity fluctuations. The current data set suggests that atmospheric fluctuations on Mt. Wilson during the best seeing are dominated by a low-lying component, approximately 25 m high, which may be minimized with in situ calibration in the future. During poor seeing conditions that currently prohibit the interferometric phase connection necessary for astrometry, fluctuations seem to be generated by atmospheric inhomogeneities at much higher altitudes above Mt. Wilson. Data taken over the last year suggest that the ISI will soon be able to achieve 50- to 100-nrad astrometry in a single observing session, employing current ground-based laser distance interferometer calibrations to minimize atmospheric effects.

Treuhaft, R. N.↗
NASA NTRS2003

Precision of a radial basis function neural network tracking method

The precision of a radial basis function (RBF) neural network based tracking method has been assessed against real targets. Precision was assessed against traditionally measured frame-by-frame measurements from the recorded data set. The results show the potential limit for the technique and reveal intricacies associated with empirical data not necessarily observed in simulations.

autonomous tracking neural network target recognit↗
NASA NTRS2023

Missed Approach Procedures in Advanced Air Mobility: Conceptual Exploration

The High Density Vertiplex Sub-Project, as part of NASA’s Advanced Air Mobility (AAM) Project, has been in collaboration with a team from Wisk Aero focusing on vertiport operations, procedures, and concept development. A particular area of focus has been on the development of missed approach scenarios and procedures that highlight the potential changes in the nearer- and further-term operational time frames. Such changes relate to topic areas such as airspace design, automation and autonomy, roles and responsibilities of actors and stakeholders, airspace management services and systems, as well as technologies specific to vertiport operations management. This paper presents the current state of joint concept development through the established collaboration and the application of elements in ongoing testing as part of NASA’s High Density Vertiplex Sub-Project’s research strategy.

vertiport↗
NASA NTRSDate not supplied

Missed Approach Procedures in Advanced Air Mobility: Conceptual Exploration

The High Density Vertiplex Sub-Project, as part of NASA’s Advanced Air Mobility (AAM) Project, has been in collaboration with a team from Wisk Aero focusing on vertiport operations, procedures, and concept development. A particular area of focus has been on the development of missed approach scenarios and procedures that highlight the potential changes in the nearer- and further-term operational time frames. Such changes relate to topic areas such as airspace design, automation and autonomy, roles and responsibilities of actors and stakeholders, airspace management services and systems, as well as technologies specific to vertiport operations management. This presentation encompasses the content of the associated paper that presents the current state of joint concept development through the established collaboration and the application of elements in ongoing testing as part of NASA’s High Density Vertiplex Sub-Project’s research strategy.

vertiport↗
NASA NTRS2004

DSP Implementation of the Multiscale Retinex Image Enhancement Algorithm

The Retinex is a general-purpose image enhancement algorithm that is used to produce good visual representations of scenes. It performs a non-linear spatial/ spectral transform that synthesizes strong local contrast enhancement and color constancy. A real-time, video frame rate implementation of the Retinex is required to meet the needs of various potential users. Retinex processing contains a relatively large number of complex computations, thus to achieve real-time performance using current technologies requires specialized hardware and software. In this paper we discuss the design and development of a digital signal processor (DSP) implementation of the Retinex. The target processor is a Texas Instruments TMS320C6711 floating point DSP. NTSC video is captured using a dedicated frame grabber card, Retinex processed, and displayed on a standard monitor. We discuss the optimizations used to achieve real-time performance of the Retinex and also describe our future plans on using alternative architectures.

Hines, Glenn D.↗
NASA NTRS2004

DSP Implementation of the Retinex Image Enhancement Algorithm

The Retinex is a general-purpose image enhancement algorithm that is used to produce good visual representations of scenes. It performs a non-linear spatial/spectral transform that synthesizes strong local contrast enhancement and color constancy. A real-time, video frame rate implementation of the Retinex is required to meet the needs of various potential users. Retinex processing contains a relatively large number of complex computations, thus to achieve real-time performance using current technologies requires specialized hardware and software. In this paper we discuss the design and development of a digital signal processor (DSP) implementation of the Retinex. The target processor is a Texas Instruments TMS320C6711 floating point DSP. NTSC video is captured using a dedicated frame-grabber card, Retinex processed, and displayed on a standard monitor. We discuss the optimizations used to achieve real-time performance of the Retinex and also describe our future plans on using alternative architectures.

Hines, Glenn↗