THE mathematics of putting an artificial satellite into orbit were known for a long time before that feat was finally accomplished. Moreover, scientists were aware that the different kinds of orbit had various exciting possibilities.
Arthur C. Clarke, better known perhaps, for his popular science fiction, is credited with being the first to suggest a geostationary orbit.
Clarke first explained his concept in a memorandum prepared for the British Interplanetary Society in May, 1945.
"The space station," he wrote, "was originally conceived as a refuelling depot for ships leaving the earth. As such it may fill an important though transient role in the conquest of space during the period when chemical fuels are employed. However, there is at least one other purpose for which the station is ideally suited, and indeed has no practical alternative. This is the problem of world wide ultra high frequency radio services, including television."
After outlining the major technical and financial implications of trying to provide world wide UHF communications on a terrestrial basis, Clarke went on:
"All these problems can be solved by the use of a chain of space stations with an orbital period of 24 hours. The stations would lie in the Earth's equatorial plane, and would thus always remain fixed in the same spots in the sky from the point of view of terrestrial observers. Unlike other heavenly bodies they would never rise nor set. This would greatly simplify the use of directive receivers installed ion the Earth."
When, some years later, Clarke's idea came to be reality, meteorologists were among the first to realise the benefits for their activities.
A geostationary satellite, being as it were fixed in space, looks down constantly at the same segment of the globe, and successive pictures taken by it at, say, half hourly intervals, can be combined to form a "movie" of the evolving weather situation.
This ambition was realised for the first time just 30 years ago today, when the first meteorological geostationary satellite went into orbit on December 6th, 1966. It was called ATS-1, the initials standing for Applications Technology Satellite, and was positioned at 150 west longitude, over the equator and the centre of the Pacific Ocean.
ATS-1 was the first of a team of five weather satellites, dotted like well spaced beads on an invisible celestial necklace high above the equator. The regular replacements of these original five now provide us with continuous pictures of the global weather.