(132K)The Applications Technology Satellite (ATS) series was conceived of as a follow-on to the successful experimental communications satellites of the early 1960's with the addition of other technology demonstrations, such as weather observation and investigation of the space environment.
NASA and Hughes had hoped to continue the success of the Syncom project with an Advanced Syncom. They met resistance from some members of Congress who feared that NASA was developing technology for the benefit of a private company, namely Comsat. So the project's objectives were broadened and it became ATS. The Department of Defense (DoD) influenced NASA to include technology for gravity-gradient stabilization (on ATS-2, ATS-4, and ATS-5) and for medium altitude orbits (ATS-2). All five of the first generation ATS spacecraft carried a C-band transponder with 25 MHz bandwidth capable of relaying 1200 one-way voice circuits or one color television signal.
The ATS 1 spacecraft shows its Syncom heritage, but at 351.5 kg (775 lb) on-orbit, with a length of 1.5 m (54 inches), was a larger and a much more capable satellite than its predecessor. In addition to a C-band transponder, ATS-1 carried a VHF experiment for communications with aircraft, ships, meteorological remote terminals, and to evaluate VHF satellite navigation. It used an eight-element phased array antenna with a 5 Watt transmitter for each element. The spacecraft was spin stabilized and had solar cells mounted around the barrel shaped body to provide 175 Watts of electrical power.
ATS-1 was the first satellite to use frequency division multiple access (FDMA) taking independently uplinked signals and converting them for downlink on a single carrier. This conserves uplink spectrum and also provides efficient power utilization on the downlink.
ATS-1 also carried a black-and-white weather camera which transmitted the first full-disk Earth images from GEO.
One of the spectacular and promising events during 1966 was the successful operation of the ATS-I spin-scan camera. This camera is providing the first high-quality cloud-cover pictures taken from an equatorial synchronous satellite. These pictures show the disk of the Earth between 52 deg. Latitude N. And S. With a resolution approaching 3 km. The camera system can take the disk pictures once every 20 minutes and smaller areas more frequently, affording a potential continuous watch of global weather patterns. Another meteorological experiment on ATS-I transmits meteorological data (weather maps, cloud analyses, and spin-scan cloud pictures) from the ATS ground station at Mojave, California, via the satellite's VHF transponder, to APT ground readout stations in the United States, Canada, Japan, Australia, and islands in the Pacific. (NASA SP-156, pg. 76)ATS-1 was launched December 7, 1966 and carried out an impressive array of experiments in communications and in collecting weather data. The communications hardware was still functioning nearly 20 years later when the spacecraft did not respond as intended to commands in 1985 and it slipped into a useless orbit.
The first five ATS spacecraft were built by Hughes for NASA's Goddard Space Flight Center.