Geodesi, Lunar Method dan Cosmic Geodesy

 

Sebelum muncul geodesi satelit geodesi pada period lampau bergantungan banyak kepada kaedah yang dipanggil lunar method. Kaedah Lunar membolehkan penyelesaian awal dalam menentukan saiz Bumi pada awal kurun ke-19. Penyelesaian tersebut didapatkan mengguna kaedah lunar serta berpandukan teori orbit. Selanjutnya, melaui inisiatif International Geophysical Year 1957/58, lahirlah pula pendekatan Cosmic Geodesy. Pendekatan CG dilaksana dengan munculnya teknologi cerapan menggunakan Dual Rate Moon Camera.

The geometrical approach in satellite geodesy also has some forerunners in the lunar methods. These methods have undergone comprehensive developments since the beginning of the last century. In this context, the Moon is regarded as a geometric target, where the geocentric coordinates are known from orbital theory. The directions between the observer and the Moon are determined from relative measurements of nearby stars, or from occultation of stars by the Moon. Geocentric coordinates are thereby received. 

Within the framework of the International Geophysical Year 1957/58 a first outcome from a global program was obtained with the Dual Rate Moon Camera, developed by Markovitz (1954). The methods of this so-called Cosmic Geodesy were treated comprehensively in 1960 by Berroth and Hofmann. They also form a considerable part of the classical book of Mueller (1964) “Introduction to Satellite Geodesy”. Further foundations to satellite geodesy before the year 1957 were given by the work of Väisälä (1946), Brouwer (1959), King-Hele (1958) and O’Keefe (1958). Therefore, it was possible to obtain important geodetic results very soon after the launch of the first rockets and satellites. One of the first outstanding results was the de-termination of Earth’s flattening as f=1/298.3 from observations of EXPLORER-1and SPUTNIK-2 by O’Keefe (1958), King-Hele, Merson (1958). 

Baca juga "Stellar triangulation" sebagai asas kepada cosmic geodesy - wiki.

[A. Berroth & W. Hofmann: Kosmische Geodäsie (Cosmic Geodesy) (356 p.), Karlsruhe 1960]

[Brouwer, Dirk, "Solution of the Problem of Artificial Satellite Theory Without Air Drag," Astronomical Journal, Vol. 64 pp. 378-397, 1959]

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