|Country of origin||United States|
|Regime||Low Earth orbit|
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". TIROS is an acronym of "Television InfraRed Observation Satellite" and is also the plural of "tiro" which means "a young soldier, a beginner".
Participants in the TIROS project included the National Aeronautics and Space Administration (NASA), United States Army Signal Research and Development Laboratory, Radio Corporation of America (RCA), the United States Weather Bureau Service, the United States Naval Photographic Interpretation Center (NPIC), the Environmental Science Services Administration (ESSA), and the National Oceanic and Atmospheric Administration (NOAA).
The 122 kg (269 lb) satellite was launched into a nearly circular low Earth orbit by a Thor-Able rocket. Drum-shaped with a 42 inches (110 cm) diameter, and height of 19 inches (48 cm), the TIROS satellite carried two 6 inches (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 achieved.
The camera shutters made possible the series of still pictures that 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.
TIROS continued as the more advanced TIROS Operational System (TOS), and eventually was succeeded by the Improved TIROS Operational System (ITOS) or TIROS-M, and then by the TIROS-N and Advanced TIROS-N series of satellites. NOAA-N Prime (NOAA-19) is the last in the TIROS series of NOAA satellites that observe Earth's weather and the environment.
The naming of the satellites can become confusing because some of them use the same name as the over-seeing organization, such as "ESSA" for TOS satellites overseen by the Environmental Science Services Administration (for example, ESSA-1) and "NOAA" (for example, NOAA-M) for later TIROS-series satellites overseen by the National Oceanic and Atmospheric Administration.
As of June 2009, all TIROS satellites launched between 1960 and 1965 (with the exception of TIROS-7) were still in orbit.
The Advanced TIROS-N (ATN) spacecraft were similar to the NOAA-A through -D satellites, apart from an enlarged Equipment Support Module to allow integration of additional payloads. A change from the TIROS-N through NOAA-D spacecraft was that spare word locations in the low bit rate data system TIROS Information Processor (TIP) was used for special instruments such as the Earth Radiation Budget Satellite (ERBE) and SBUV/2. The search and rescue (SAR) system became independent, utilizing a special frequency for transmission of data to the ground.
NOAA exclusively operates afternoon polar orbit spacecraft, while its key international partner, the European Organisation for the Exploitation of Meteorological Satellites (EUMETSAT), flies mid-morning orbit spacecraft.
A last-of-its-kind weather observatory...
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