“What if the weather moves, not the satellite?”
The satellite era began in 1957 when the Soviet Union hurtled Sputnik into a low-Earth orbit, launching the world into the space race. In the years that followed, dozens of satellites, used to view Earth’s weather from space, communicate around the world, and study the near-Earth environment, were placed in low-Earth and polar orbits. The first weather experiment, an instrument used to measure Earth’s radiation budget, was flown aboard Explorer VII, launched by the U.S. on October 13, 1959.
The world’s first operational meteorological satellite, TIROS-1, circumnavigated the globe for the first time in 1960, forever proving the worth of weather observing satellites to the world and opening the door for the weather systems of the future.
As these early satellites raced around the globe a few hundred miles above the surface, they captured an impressive array of visible and infrared imagery of the planet in narrow segments, or swaths, that were later stitched together to create a full image. Although these satellites revolutionized scientists’ understanding of localized weather phenomena, it was still very difficult to grasp global weather circulation, the key to better weather prediction.
The question quickly became, “How does one continuously monitor the movement of weather over large portions of earth’s surface?” The answer, as it turns out, was more than 22,000 miles away in geostationary orbit.
The launch of ATS-1
On December 6, 1966, a NASA Atlas rocket carried the Applications Technology Satellite, or ATS-1, into geostationary orbit. From there, the satellite was able to precisely match the spin of our planet on its axis and remain over a fixed point on the surface.
ATS-1, and the six models that followed, served as a platform for evaluating different kinds of spacecraft stabilization and communications techniques, while also carrying several scientific and meteorological experiments.
During its 18-year life, ATS-1 tested spin-stabilization and 3-axis stabilization systems, investigated the geostationary environment, tested the ability to act as a link between ground stations and aircraft, demonstrated collection of meteorological data from remote terminals, and evaluated the feasibility of using VHF signals for navigation. It also transmitted educational programs and provided health, research, and community services to the United States and several Pacific locations, including the Cook, Mariana, Marshall and Caroline Islands, as well as West and American Samoa, Melanesia, New Zealand and Australia.
The satellite was also responsible for providing the first full-disk image of Earth ever taken from geostationary orbit.
The Spin-Scan Cloud-cover Camera
One of the many instruments aboard ATS-1 was the spin-scan cloud-cover camera, invented by Verner Suomi, the “Father of Satellite Meteorology.” Suomi, and his co-inventor, Robert Parent, both worked at the University of Wisconsin in Madison. Since the first weather experiment launched in 1959, the UW-Madison Space Science and Engineering Center (SSEC) has been at the forefront of developing the satellite technology that allows scientists around the world to view and study Earth from space.
Because ATS-1 spun to stay stabilized in space, taking an image of Earth became rather tricky. To overcome this, the camera scanned a small strip of the Earth with each rotation of the satellite. By tilting the mirror slightly for the next rotation, an image of Earth could be pieced together line by line in less than 30 minutes.
Suddenly, scientists could see weather moving around an entire hemisphere while the satellite seemed to remain still, revolutionizing weather forecasting forever.
Continuing the Legacy
After the success of ATS-1 and Suomi’s invention, the multi-color spin scan camera was flown on ATS-3 in 1967, which captured the first full-color image of Earth from space.
The first six geostationary ATS satellites, and their meteorological experiments, paved the way for NASA’s Synchronous Meteorological Satellite (SMS) series. It did not take long (October 1975) before the SMS-1 and -2 geostationary weather satellite experiments morphed into NOAA’s Geostationary Operational Environmental Satellite (GOES) program, today’s weather eyes in the sky.