Sunday, November 8, 2020

Perkembangan Geodesi Satelit 1958-1980

 

Seeber juga turut merumuskan sejarah perkembangan geodesi satelit sepanjang period awal penciptaan satelit iaitu dari 1958 sehingga period 1980-an.

1958 to around 1970.

Development of basic methods for satellite observations, and for the computation and analysis of satellite orbits. This phase is characterized by the optical-photographic determination of directions with cameras.  The main results were the determination of the leading harmonic coefficients of the geopotential, and the publication of the first Earth models, for instance the Standard Earth models of the Smithsonian Astrophysical Observatory (SAO SE I to SAO SE III), and the Goddard Earth Models (GEM) of the NASA Goddard Space Flight Center. The only purely geometrical and worldwide satellite network was established by observations with BC4 cameras of the satellite PAGEOS.

1970 to around 1980.

Phase of the scientific projects. New observation techniques were developed and refined, in particular laser ranging to satellites and to the Moon, as well as satellite altimetry.  The TRANSIT system was used for geodetic Doppler positioning. Refined global geoid and coordinate determinations were carried out, and led to improved Earth models (e.g. GEM 10, GRIM). The increased accuracy of the observations made possible the measurement of geodynamical phenomena (Earth rotation, polar motion, crustal deformation). Doppler surveying was used worldwide for the installation and maintenance of geodetic control networks (e.g. EDOC, DÖDOC, ADOS). 

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