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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 487 records · Page 27
All sourcesNASA NTRSDOE OSTI
NASA NTRS1974

A system to geometrically rectify and map airborne scanner imagery and to estimate ground area

A system of computer programs were developed which performs geometric rectification and line-by-line mapping of airborne multispectral scanner data to ground coordinates and estimates ground area. The system requires aircraft attitude and positional information furnished by ancillary aircraft equipment, as well as ground control points. The geometric correction and mapping procedure locates the scan lines, or the pixels on each line, in terms of map grid coordinates. The area estimation procedure gives ground area for each pixel or for a predesignated parcel specified in map grid coordinates. The results of exercising the system with simulated data showed the uncorrected video and corrected imagery and produced area estimates accurate to better than 99.7%.

Spencer, M. M.↗
NASA NTRS1973

Evaluation of digitally corrected ERTS imagery

Utilizing all digital processing techniques, precision rectified ERTS multispectral imagery have been produced. Precision geometric correction is accomplished by: (1) utilizing a low order piecewise approximation to the image distortions; (2) incorporating spacecraft attitude refinement derived from ground control points utilized in a Kalman filter; (3) utilizing interpolation techniques which preserve value and slope continuity in the image data. Imagery produced is represented in a UTM projection, and has been evaluated for precision by statistical and analytical methods. Extrapolations to modest size computers indicate good throughput with no sacrifice in precision.

Rifman, S. S.↗
NASA NTRS1974

A general solution for the registration of optical multispectral scanners

The paper documents a general theory for registration (mapping) of data sets gathered by optical scanners such as the ERTS satellite MSS and the Skylab S-192 MSS. This solution is generally applicable to scanners which have rotating optics. Navigation data and ground control points are used in a statistically weighted adjustment based on a mathematical model of the dynamics of the spacecraft and the scanner system. This adjustment is very similar to the well known photogrammetric adjustments used in aerial mapping. Actual tests have been completed on NASA aircraft 24 channel MSS data, and the results are very encouraging.

Rader, M. L.↗
NASA NTRS1974

Photogrammetric measurements of Olympus Mons on Mars

Mariner 9 took many pictures of the giant Olympus Mons during its year in orbit around Mars. Control points have been identified on the top of Olympus Mons, on the volcanic shield, and on the surrounding plains, and their locations have been measured on the television pictures. These measurements were used to compute the areographic coordinates and the planetary radii of the points. The radii at some of the points were derived from radar elevation measurements and from radio occultation measurements. The mountain rises about 21 km above its base.

Davies, M. E.↗
NASA NTRS1974

The elevation of Olympus Mons from limb photography

Using a novel photogrammetric technique, the relative elevations of a set of control points on the Martian volcano Olympus Mons (Nix Olympica) have been measured from Mariner 9 limb pictures that include the volcano in the foreground. The summit of Olympus Mons is found to be 22 plus or minus 1 km above the mean level of the surrounding plain by correlating the elevation results with previously reported planet radii at nearby occultation points. Vertical elevation differences as great as 5 km were measured between close points on the basal scarp.

Whitehead, A. B.↗
NASA NTRS1974

Correlation and registration of ERTS multispectral imagery

Examples of automatic digital processing demonstrate the feasibility of registering one ERTS multispectral scanner (MSS) image with another obtained on a subsequent orbit, and automatic matching, correlation, and registration of MSS imagery with aerial photography (multisensor correlation) is demonstrated. Excellent correlation was obtained with patch sizes exceeding 16 pixels square. Qualities which lead to effective control point selection are distinctive features, good contrast, and constant feature characteristics. Results of the study indicate that more than 300 degrees of freedom are required to register two standard ERTS-1 MSS frames covering 100 by 100 nautical miles to an accuracy of 0.6 pixel mean radial displacement error. An automatic strip processing technique demonstrates 600 to 1200 degrees of freedom over a quater frame of ERTS imagery. Registration accuracies in the range of 0.3 pixel to 0.5 pixel mean radial error were confirmed by independent error analysis. Accuracies in the range of 0.5 pixel to 1.4 pixel mean radial error were demonstrated by semi-automatic registration over small geographic areas.

Bonrud, L. O.↗
NASA NTRS1974

Earth Observatory Satellite system definition study. Report no. 7: EOS system definition report. Appendixes A through D

An analysis of the systems involved in the operation and support of the Earth Observatory Satellite (EOS) is presented. Among the systems considered are the following: (1) the data management system, (2) observatory to primary ground station communications links, (3) local user system, (4) techniques for recognizing ground control points, (5) the central data processing-implementation concept, and (6) program effectiveness analysis.

Source record↗
NASA NTRS1975

Unsteady vortex lattice techniques applied to wake formation and performance of the statically thrusting propeller

The application is considered of vortex lattice techniques to the problem of describing the aerodynamics and performance of statically thrusting propellers. A numerical lifting surface theory to predict the aerodynamic forces and power is performed. The chordwise and spanwise loading is modelled by bound vortices fixed to a twisted flat plate surface. In order to eliminate any apriori assumptions regarding the wake shape, it is assumed the propeller starts from rest. The wake is generated in time and allowed to deform under its own self-induced velocity field as the motion of the propeller progresses. The bound circulation distribution is then determined with time by applying the flow tangency boundary condition at certain selected control points on the blades. The aerodynamics of the infinite wing and finite wing are also considered. The details of wake formation and roll-up are investigated, particularly the localized induction effect. It is concluded that proper wake roll-up and roll-up rates can be established by considering the details of motion at the instant of start.

Hall, G. F.↗
NASA NTRS1974

Lifting-surface theory for a semi-infinite wing in oblique gust

An unsteady lifting-surface theory is developed for the calculation of the airload on a semi-infinite-span thin wing in a compressible flow due to interaction with an oblique gust. By using the solutions obtained for a two-dimensional wing, the problem is formulated so that the unknown is taken to be the difference between the airload on the semi-infinite wing and that on a two-dimensional wing under the same gust conditions. Since this airload difference is nonzero only near the wing tip, the control points need be distributed in the tip region only; this significantly simplifies the numerical procedure. Results are presented for a wing with rectangular tip. The implication for noise and unsteady loads due to blade-vortex interaction for helicopter rotors is discussed.

Chu, S.↗
NASA NTRS1975

Advanced panel-type influence coefficient methods applied to subsonic flows

An advanced technique for solving the linear integral equations of three-dimensional subsonic potential flows (steady, inviscid, irrotational and incompressible) about arbitrary configurations is presented. It involves assembling select, logically consistent networks whose construction comprises four tasks, which are described in detail: surface geometry definition; singularity strength definition; control point and boundary condition specification; and calculation of induced potential or velocity. The technique is applied to seven wing examples approached by four network types: source/analysis, doublet/analysis, source/design, and doublet/design. The results demonstrate the forgiveness of the model to irregular paneling and the practicality of combined analysis/design boundary conditions. The appearance of doublet strength mismatch is a valuable indicator of locally inadequate paneling.

Johnson, F. T.↗
NASA NTRS1975

The influence of man in space observations

The paper evaluates the Skylab missions from the viewpoint of to what extent the presence of men may have been a detriment to scientific observations, either through their movements or through contamination of the spacecraft and instruments. The stability of the instrument canister within the Apollo Telescope Mount was secured by the Experiment Pointing Control System. Angular stability was specified to be within plus or minus 2.5 arc seconds, and was found to be less than 2 arc seconds during normal crew activity. No astronomical observations were reported as being degraded by crew movements. Instrumentation was installed to measure rates of contaminant particle deposition on optical surfaces. Clouds were formed from particles originating in outgassing from vehicle surface materials and from vent apertures. The Coronograph Contamination Measurement Instrument was used to measure the brightness of the induced cloud surrounding Skylab. Preliminary analysis shows no significant degradation of photographic data attributable to contamination.

Hanes, T. E.↗
NASA NTRS1976

Pointing control/roll positioning mechanism

Telescope mount provides torquing for a fine-pointing servosystem in both pitch and yaw. Use of flexure bearings in EPC (experiment pointing control) actuator package offers performance and reliability superior to that of other bearing configurations.

Kohman, W. E.↗
NASA NTRS1973

Precision Attitude Determination System (PADS) design and analysis. Two-axis gimbal star tracker

Development of the Precision Attitude Determination System (PADS) focused chiefly on the two-axis gimballed star tracker and electronics design improved from that of Precision Pointing Control System (PPCS), and application of the improved tracker for PADS at geosynchronous altitude. System design, system analysis, software design, and hardware design activities are reported. The system design encompasses the PADS configuration, system performance characteristics, component design summaries, and interface considerations. The PADS design and performance analysis includes error analysis, performance analysis via attitude determination simulation, and star tracker servo design analysis. The design of the star tracker and electronics are discussed. Sensor electronics schematics are included. A detailed characterization of the application software algorithms and computer requirements is provided.

Source record↗
NASA NTRS1976

A summary of the Skylab crew/vehicle disturbances experiment T-013

A manned space flight experiment (designated experiment T-013) to assess the characteristics of astronaut crew-motion disturbances was conducted on the second manned Skylab mission. A brief description of the experiment hardware utilized is given, and a comprehensive discussion of the experiment data reduction and analysis is presented. Data obtained from a force-measuring system, an astronaut limb-motion measuring system, motion-picture film, and the Skylab attitude and pointing control system is described. Results show that astronaut crew members can produce significant disturbance inputs to a spacecraft's attitude control system. Total forces of up to 400 N were exerted during vigorous soaring activities, whereas ""restrained'' motions by the experiment subject generated total forces of up to 300 N. A discussion of potential applications of the experiment results is given and appendixes provide additional detail with respect to experiment operations and results.

Conway, B. A.↗
NASA NTRS1976

Arrangement of vortex lattices

A new method is developed for solving the lifting-surface equation for thin wings. The solution requires the downwash equation to be in the form of Cauchy integrals which can be interpreted as a vortex lattice with the positions of the vortices and control points dictated by the finite sum used to approximate the integrals involved. Lan's continuous loading method is employed for the chordwise integral since it properly accounts for the leading-edge singularity, Cauchy singularity, and Kutta condition. Unlike Lan, the spanwise loading is also continuous and the Cauchy singularity in the spanwise integral is also properly accounted for by using the midpoint trapezoidal rule and the theory of Chebyshev polynomials. This technique yields the exact classical solution to Prandtl's lifting-line equation.The solution to the lifting-surface equation for rectangular wings was found to compare well with other continuous loading methods, but with much smaller computational times, and to converge faster than other vortex lattice methods.

Dejarnette, F. R.↗
NASA NTRS1975

Orbiter entry trajectory corridors: 32000 pound payload, 67.5 percent center of gravity

Thermal and equilibrium glide boundaries were used to analyze and/or design shuttle orbiter entry trajectories. Plots are presented of orbiter thermal and equilibrium glide boundaries in the drag/mass-relative velocity dynamic pressure-relative velocity, and altitude-relative velocity planes for an orbiter having a 32,000 pound payload and a 67.5% center of gravity location. These boundaries were defined for control points 1 through 4 of the shuttle orbiter for 40 deg-30 deg and 38 deg-28 deg ramped angle of attack entry profiles and 40 deg, 38 deg, 35 deg, 30 deg, 28 deg, and 25 deg constant angle of attack entry profiles each at 20 deg, 15 deg, and 10 deg constant body flap settings.

Treybig, J. H.↗
NASA NTRS1976

National Aeronautics and Space Administration /NASA/ Sounding Rocket Program

An overview of the NASA Sounding Rocket Program is presented. The program has launched a total of 1912 rockets representing 30 types of vehicle configurations. Payloads have been primarily directed to the disciplines of magnetodynamics, solar physics, stellar and planetary astronomy and meteorology. The vehicles, launching sites, and launching techniques used in the program are described, and the pointing control systems and command links developed in the course of the program are discussed.

Holtz, J. R.↗