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Gravity field measurement by satellite to satellite Doppler tracking, critical configurations for fundamental range networks, and improvement of triangulation systems
Electronically controlled camera system for optical sattellite triangulation data acquisition
Traveling ionospheric disturbances dynamic properties, calculating horizontal phase velocity from triangulation data
Hyperbolic triangulation method was used for locating lightning storm path and position from VHF lightning charge emissions. Possible applications in electric power companies, forest fire lookout centers, airports, and pipeline companies are indicated.
A study to correlate stress wave emission characteristics with fracture in welded and unwelded aluminum alloys tested at room and cryogenic temperature is reported. The stress wave emission characteristics investigated were those which serve to presage crack instability; viz., a marked increase in:(1) signal amplitude; (2) signal repetition rate; and (3) the slope of cumulative count plotted versus load. The alloys were 7075-T73, 2219-T87 and 2014-T651, welded with MIG and TIG using 2319 and 4043 filler wire. The testing was done with both unnotched and part-through-crack (PTC) tension specimens and with 18-in.-dia subscale pressure vessels. In the latter testing, a real time, acoustic emission, triangulation system was used to locate the source of each stress wave emission. With such a system, multiple emissions from a given location were correlated with defects found by conventional nondestructive inspection.
The Apollo 15 mission was the fourth manned lunar landing and the northernmost location yet visited. The landing site on the southeastern edge of the Imbrium Basin afforded the opportunity of studying several unique lunar features, the Apennine Mountains, Hadley Rille, and the Imbrium Basin fill. Detailed geological study of the data returned from the mission provided new insight into the structure and history of the Basin. A third Apollo Lunar Surface Experiment Package was deployed during the mission containing seven experiments: Passive Seismometer (PSE), Heat Flow (HFE), Surface Magnetometer (LSM), Suprathermal Ion Detector (SIDE), Cold Cathode Gauge (CCGE), Solar Wind Spectrometer (SWS), and a Dust Detector. We have been able to triangulate on the sources of moonquakes and to observe simultaneous nighttime and daytime changes in the moon's magnetic field, solar wind flux, and the neutral and ionized components of the moon's tenuous atmosphere.
The author has identified the following significant results. Two strips of U-2 RC-10 images were analytically triangulated and adjusted. Control points and pass points were marked on glass plates made from B&W copy negatives of IR color transparencies. A wild PUG-3 and TA1/p monocomparator were used to mark and measure the points on the glass plates. Each plate was measured twice in the same orientation for a check on accuracy and operator error. The 22 photographs were adjusted to 41 ground control and tie points and the block adjustment was performed in a secant plane coordinate system to eliminate the effect of earth curvature. Standard deviations of the residuals of the control and tie points were 12.8 m, 10.8 m, and 4.5 m for the X, Y, and Z coordinates respectively. The 12.8 m and 10.8 m figures correspond to an identification accuracy of 0.1 mm on the U-2 RC-10 plates. The standard deviations of the residuals encountered in the ERTS-1 resectioning were: (1) 0.16 mm assuming uncorrected perspective geometry and (2) 0.12 mm when the polynomial adjustment was added in. These results indicate a reduction of 0.11 in the square error due to the polynomial adjustment.
Apollo 16 photography during lunar orbit of the Gegenschein-Moulton region was used to determine the libration points of the Sun-Earth system. Triangulation for the system is discussed, along with background experimental information.
The feasibility of generating artificial auroras by injecting electrons into the upper atmosphere was investigated by using an electron accelerator aboard an Aerobee 350 rocket. Four of the artificial auroral rays were detected and recorded by two geophysical sites separated enough to enable the spatial coordinates of the rays to be determined by triangulation. It was found that (1) the beam remained well collimated; (2) most of the initial beam energy was deposited in the atmosphere; (3) plasma instabilities did not play a significant role; and (4) the orientations of the rays were determined with sufficient accuracy to improve the knowledge of the earth's magnetic field over the Virginia coast. The publications resulting from this research are listed.
Simultaneously occuring dispersive and convective components of fluid kinematics are obtained by a time domain analysis of optically retrieved temporal histories of the transport phenomena. Utilizing triangulation of collimated optical fields of view from two radiometers to obtain the temporal histories of the intensity fluctuations associated with the transport phenomena has enabled investigators to retrieve the local convective transport by employing correlation statistics. The location of the peak in the covariance curve determines the transit time from which the convection velocity is calculated; whereas, the change in shape of the peak in the covariance curve determines the change in average frequency of the wave packet from which the dispersion velocity is calculated. Thus, two-component analysis requires the maximum possible enhancement of the delineation for the transport. The convection velocity is the result of a fixed reference frame calculation whereas, the dispersion velocity is the result of a moving reference frame calcuation.
In lunar phototriangulation, there is a complete lack of accurate ground control points. The accuracy analysis of the results of lunar phototriangulation must, therefore, be completely dependent on statistical procedure. It was the objective of this investigation to examine the validity of the commonly used statistical procedures, and to develop both mathematical techniques and computer softwares for evaluating (1) the accuracy of lunar phototriangulation; (2) the contribution of the different types of photo support data on the accuracy of lunar phototriangulation; (3) accuracy of absolute orientation as a function of the accuracy and distribution of both the ground and model points; and (4) the relative slope accuracy between any triangulated pass points.
Geodetic parameters describing the earth's gravity field and the positions of satellite-tracking stations in a geocentric reference frame were computed. These parameters were estimated by means of a combination of five different types of data: routine and simultaneous satellite observations, observations of deep-space probes, measurements of terrestrial gravity, and surface-triangulation data. The combination gives better parameters than does any subset of data types. The dynamic solution used precision-reduced Baker-Nunn observations and laser range data of 25 satellites. Data from the 49-station National Oceanic and Atmospheric Administration BC-4 network, the 19-station Smithsonian Astrophysical Observatory Baker-Nunn network, and independent camera stations were employed in the geometrical solution. Data from the tracking of deep-space probes were converted to relative longitudes and distances to the earth's axis of rotation of the tracking stations. Surface-gravity data in the form of 550-km squares were derived from 19,328 1 deg X 1 deg mean gravity anomalies.
Examples are given of coordinated programs in Alaska which involve satellites, radars, ground optical instrumentation, and other types of observing satellites for the study of atmospheric and magnetospheric geophysics. Programs include coincidence data acquisition, scheduled data acquisition, and planned experiments. The use of optical triangulation techniques to determine the position of the aurora in order to place the other measurements in the perspective of the overall auroral morphology is detailed.
Description of activities associated with photogrammetric reduction of photography and support data gathered by Apollo spacecraft in lunar orbit. The aim of these activities is to combine all data from Apollo 15, 16, and 17 missions for the purpose of forming a unified control system on the moon called the Apollo Control Network. The status of efforts at reduction of data from each of these missions is summarized along with a proposed scheme for combining the three missions in a simultaneous reduction. Plans to expand the network by use of Apollo oblique mapping photography are also discussed, and the results of an oblique triangulation test are evaluated.
A description is given of a digital computer program which prepares contour plots of three dimensional data. The contouring technique uses a triangulation procedure. As presently configured, the program can accept up to 56,000 randomly spaced data points, although the required computer resources may be prohibitive. However, with relatively minor internal modifications, the program can handle essentially unlimited amounts of data. Up to 20 contouring intervals can be selected and contoured with either polygonal lines or smooth curves. Sample cases are illustrated. A general description of the main program and primary level subroutines is included to permit simple modifications of the program.
The functional requirements and operating environment constraints are defined for an independent landing monitor ILM which provides the flight crew with an independent assessment of the operation of the primary automatic landing system. The capabilities of radars, TV, forward looking infrared radiometers, multilateration, microwave radiometers, interferometers, and nuclear sensing concepts to meet the ILM conditions are analyzed. The most critical need for the ILM appears in the landing sequence from 1000 to 2000 meters from threshold through rollout. Of the sensing concepts analyzed, the following show potential of becoming feasible ILM's: redundant microwave landings systems, precision approach radar, airborne triangulation radar, multilateration with radar altimetry, and nuclear sensing.
Geodetic parameters describing the earth's gravity field and the positions of satellite-tracking stations in a geocentric reference frame have been computed. These parameters were estimated by means of a combination of five different types of data: routine and simultaneous satellite observations, observations of deep space probes, measurements of terrestrial gravity, and surface triangulation data. The combination gives better parameters than does any subset of data types. The dynamic solution used precision-reduced Baker-Nunn observations and laser range data of 25 satellites. Data from the 49-station National Oceanic and Atmospheric Administration BC-4 network, the 19-station Smithsonian Astrophysical Observatory Baker-Nunn network, and independent camera stations were employed in the geometrical solution.
Computer program using triangulation contouring technique contours data points too numerous to fit into rectangular grid. Using random access procedures, program can handle up to 56,000 data points and provides up to 20 contour intervals for multiple number of parameters.