Television Infrared Observation Satellite

TIROS, or Television Infrared Observation Satellite, is a series of early weather satellites launched by the United States, beginning with TIROS-1 in 1960. TIROS was the first satellite that was capable of remote sensing of the Earth, enabling scientists to view the Earth from a new perspective: space. The program, promoted by Harry Wexler, proved the usefulness of satellite weather observation, at a time when military reconnaissance satellites were secretly in development or use. TIROS demonstrated at that time that "the key to genius is often simplicity".

The 270 lb (122 Kg) satellite was launched into a nearly circular low earth orbit by a Thor Able rocket. Drum-shaped with a 42 inch (1.1 m) diameter, and height of 19 inches (48 cm), the TIROS satellite carried two six-inch (15 cm) long television cameras. One of the cameras had a wide-angle lens with an f /1.6 aperture that could view an 800-mile-wide area of the Earth. The other camera had a telephoto lens with an f /1.8 aperture and 10- to 12-power magnification compared to the wide angle camera.

The satellite itself was stabilized in its orbit by spinning like a gyroscope. When it first separated from the rocket's third stage, it was spinning at about 136 revolutions per minute (rpm). To take unblurred photographs, a de-spin mechanism slowed the satellite down to 12 rpm after the orbit was accomplished.

The camera shutters made possible the series of still pictures which were stored and transmitted back to earth via 2-watt FM transmitters as the satellite approached one of its ground command points. After transmission, the tape was erased or cleaned and readied for more recording.

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