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All sourcesNASA NTRSDOE OSTI
NASA NTRS1971

Observations and reduction techniques of the US Coast and Geodetic Survey

The plate reduction method and other aspects of the world geodetic net are described. About one hundred stars are used as reference stars on the PAGEOS satellite plates obtained on 300mm f.1. and later 450mm f.1. Wild BC-4 cameras. The measurements are made manually now on diapositives since these can, according to experience, be measured with higher accuracy and are adjusted following a rigorous projective geometric model. The satellite images are analytically represented by a polynomial curve, of which seven fictitious points are regarded as the result from this plate. Some other aspects of the program are also discussed.

Schmid, H. H.↗
NASA NTRS1972

Basic research and data analysis for the National Geodetic Satellite Program

Investigations of triangulation nets and scaling are reported. Adjustment of the BC-4 worldwide geometric satellite triangulation net is described, along with procedures for correcting type II data and the contents of magnetic tapes containing data from the Pageos network. Computational steps for the further reduction of partially reduced satellite image plate coordinates are outlined. The problem of improving existing triangulation systems by means of satellite super-control points was studied. The SAO-69 geometric solution was scaled with C-band radar data, resulting in SAO and C-band adjustment compatible with one another in the Western Hemisphere. The North America solution NA-6, obtained from GEOS 1 data, was readjusted with new heights as constraints on all 30 optical stations and is referred to as the NA-8 solution.

Source record↗
NASA NTRS1972

Observed effects of earth-reflected radiation and hydrogen drag on the orbital accelerations of balloon satellites.

From March through May 1967, the high-altitude balloon satellites Pageos (1966 56A) and Dash 2 (1963 30D) were both in continuous sunlight orbits. Observed variations in the orbital accelerations of both satellites are found to be due primarily to a combination of the perturbing effects of earth albedo radiation and atmospheric drag. An equation based on diffuse Lambertian reflection of sunlight from the earth predicts quite well the observed trend of orbital accelerations for both satellites due to the force of earth albedo radiation. After correcting for this effect, the remaining orbital energy changes are found to be consistent with atmospheric drag perturbations, making it possible to deduce mean exospheric densities above 2300 km. The results indicate that hydrogen concentrations during the observation period were about three times greater than that given by the U.S. Standard Atmosphere Supplements (1966).

Prior, E. J.↗
NASA NTRS1972

Measured physical and optical properties of the passive geodetic satellite /Pageos/ and Echo 1.

Two satellites used for geodesy, Pageos and Echo 1, have been observed in a continuing program since 1966 to determine the stability of their physical and optical properties. Measurements are made in the UBVRI spectral system. The amount of solar radiation reflected from a satellite's surface is measured photoelectrically and is calibrated against known stellar magnitudes by standard astronomical techniques. The calibrated satellite magnitudes are analyzed with respect to the sun-satellite-observer phase angle to infer the shape and size of the satellite and the reflective properties of the satellite's surface material. The physical and optical properties are used to determine proper position of the solar image on the satellite's surface, resulting in more precise geometric geodesy. Quantitative results from five observing periods indicate that, although local structural anomalies appear to exist, both satellites essentially maintained their nominal average 30.48-meter (50-ft) radius of curvature and specular reflecting characteristics.

Mcdougal, D. S.↗
NASA NTRS1975

Station coordinates in the Standard Earth III system derived by using camera data from ISAGEX

Simultaneous and individual camera observations of Geos 1, Geos 2, Pageos, and Midas 4 obtained during the International Satellite Geodesy Experiment are used to determine station coordinates. The Smithsonian Astrophysical Observatory Standard Earth III system of coordinates is utilized to tie the geometrical network to a geocentric system and as a reference for calculating satellite orbits. The normal systems for geometrical and dynamical solutions are combined.

Gaposchkin, E. M.↗