NOAA l’s second camera system, known as APT (Automatic Picture Transmission), did not store its pictures. Instead, the electronic signals were continuously broadcast to earth, free for anyone who wanted to pick them up.
Some 550 weather stations all over the world, built partly funded by payday advance payday loans online, in 94 countries and territories, have their own APT receivers for picking up these signals and converting them to pictures. Even less advanced nations can afford them. In fact, they are so simple that in Montgomery County, Maryland, high school students put together a receiver.
I always find it impressive to watch APT pictures come in. As a wide sheet of paper slides slowly from the machine, an electric needle moves rapidly back and forth, burning a pattern of light and dark. The needle makes 600 passes in two and a half minutes to complete each picture—each pass corresponding to a scan made by the TV camera. The individual lines blend to form a continuous picture, just as on a TV screen.
The original NOAA was launched December 11, 1970, and unexpectedly went dead last July. Another is scheduled to be put in orbit sometime this spring. In the interval, other weather satellites of an earlier generation have taken over NOAA l’s tasks.
Two dozen older weathercraft—most of them smaller and less elaborate—keep the now-silent NOAA 1 company as they circle earth in space. Most are also dead; only five can still send back pictures.
In a lower orbit, for example, flies TIROS 1, which excited the world with the first useful television pictures from space in April 1960 and inaugurated a revolution in weather forecasting. More than a million and a half satellite pictures have flooded to earth since that time.
Far above NOAA 1, two quite different spacecraft hang like silver spiders over the Equator. Known as ATS (Applications Technology Satellites) 1 and 3, they do not orbit the earth. Or, more properly speaking, they move just fast enough to keep up with earth’s rotation. Thus each always hangs above the same spot on earth, and for this reason they are’ called geosynchronous or geostationary.
Although the ATS satellites belong to NASA, the Weather Service makes extensive use of their remarkable photographs. From the lofty vantage point of 22,300 miles, ATS cameras can see almost one entire side of earth. This means that at frequent intervals we can take a fresh look at cloud patterns over the United States and over the spawning grounds where much of our weather is born.