By Sharon Watkins Lang (SMDC/ARSTRAT Command Historian)November 23, 2017
REDSTONE ARSENAL, Alabama -- In another year in which the weather has dominated the news around the world, it is fitting to pause and recognize the early advances in meteorological exploration.
One such initiative was the TIROS or Television Infrared Observation Satellite Program, the first weather satellite that dates back to 1960. The first of 10 TIROS launches occurred in April, followed soon thereafter by the launch of TIROS II, Nov. 23, from Cape Canaveral, Florida.
These first TIROS launches were a joint venture that included NASA, the Radio Corporation of America, the U.S. Weather Bureau, now known as the National Oceanic and Atmospheric Administration, the U.S. Naval Photographic Interpretation Center and the U.S. Army Signal Research and Development Lab. The Army Ordnance Corps, had previously assigned the Signal Corps "that portion of this problem that involves meteorological instrumentation, including television systems for meteorological purposes…. "
With each launch, the TIROS program continued to evolve. TIROS I, which was operational for only 78 days, sought to test television techniques to develop a "worldwide meteorological satellite information system." To achieve this goal, the 270-pound space craft constructed of an aluminum alloy and stainless steel and powered by more than 9,000 solar cells, contained two 35-mm cameras - one low-resolution and the other a high-resolution.
The wide-angle lens camera was able to photograph 800-square miles while the other camera focused upon 30- square miles. The two cameras were connected to magnetic video tape recorders equipped with timing mechanisms that stored the images until the satellite was within range of one of the two ground stations, located at the Army Signal Corps Labs at Fort Monmouth, New Jersey, and an Air Force facility at Kaena Point, Hawaii.
Over the course of the 78 days, orbiting the earth once every 98 minutes, the TIROS I cameras captured nearly 23,000 images and clearly showed the cloud cover views of the Earth and demonstrated that satellites were a beneficial tool in "surveying global weather conditions."
With a similar construction design, the TIROS II added new equipment to improve upon the quality of the data collected. In addition to the two cameras and recorders, TIROS II adopted noise suppressor circuits and a miniaturized radio frequency diplexer. Other innovations included an infrared horizon sensor for attitude control, a direction indicator for picture orientation, a magnetic orientation control experiment, and two infrared radiation experiments.
The TIROS II flight suffered some setbacks with the television camera system. Debris on the lens of the wide-angle camera affected the quality of many of these images. The narrow angle camera remained fully functioning until Feb. 1, 1961, but after that produced only sporadic images until Sept. 27, 1961. Nevertheless the experiment collected more than 25,000 usable pictures, which are housed in the National Climatic Center, in Ashville, North Carolina.
The two radiation experiments included a five-channel scanning radiometer and a low-resolution, non-scanning, two-channel radiometer. The widefield radiometer meanwhile consisted of two detectors -- a black and a white thermistor bolometers.
The black detector "responded equally to reflected solar radiation and long-wave terrestrial radiation." The white detector meanwhile reflected solar and visible radiation but measured only long-wave thermal radiation." Unfortunately, the sensors were not as sensitive as anticipated, so the data from this experiment has been described as "too ambiguous for reduction or analysis.'
The scanning radiometer, meanwhile, scanned the Earth and space, measuring the emitted and reflected radiation of the Earth and its atmosphere. Each channel focused upon a specific facet to be studied -- water vapor absorption, atmospheric window, reflected solar radiation, terrestrial radiation and reflected solar radiation.
Scientists collected five months of data before the motor for the radiometer failed in April 1961. Analysis of the data found that "radiation data may be useful not only for determining the location, motion and development of frontal systems but also for obtaining information on the structure of frontal zones."
TIROS SERIES CONTINUE TO EVOLVE
Each launch of the TIROS series, which began with the Army and NASA, improved weather forecasting capabilities. TIROS-3 for example, made an extensive study of the 1961 hurricane season and is credited with discovering Hurricane Esther.
TIROS-4 allowed the U.S. Weather Bureau to share cloud images with other nations. TIROS-6 expanded the study to the detection of snow cover. TIROS-9 is credited with creating a complete view of the world's weather. And finally TIROS-10 produced more than 400 images a day covering 640,000 square miles each, with a 2-mile resolution at the center.