The TIROS series (Television Infrared Observations Satellites) were designed to test the feasibility of weather observation from orbit. The TIROS satellite on exhibit was the prototype for the entire series of vehicles. The prototype made eight trips to the launch stand at Cape Kennedy, where it was used to check communications and handling procedures prior to the launch of the scheduled TIROS. All 10 TIROS satellites were successful. Launched between April 1, 1960, and July 1, 1965, they carried a variety of camera systems for experimental purposes. Nine TIROS Operational Satellites (TOS) followed _TIROS 1-10_. Except for the first TOS, these satellites flew in pairs with one craft storing pictures on board for later transmission to major receiving centers, while the other broadcast its photographs continuously to any ground station within range. The satellite on display is of the latter type. These vehicles were launched between 1966 and 1969. They were placed in near-polar orbits by reliable Thor-Delta launch vehicles. [Illustration: 36. _TIROS I_ photo showing a section of the East coast of the United States, including the Boston and New England area.] After launch, TOS vehicles were referred to as ESSA satellites. ESSA was an acronym both for Environmental Survey Satellite and for the Environmental Science Service Administration, the federal agency that operated the spacecraft. This organization became a part of the National Oceanic and Atmospheric Administration which currently has responsibility for operational meteorological satellite programs. From about 1392 kilometers (865 miles) above Earth, two wide-angle television cameras mounted on either side of the spacecraft took in 10.4-million square kilometers (4-million square miles) per photo. The Improved TIROS Operational Satellite (ITOS) opened the world of radiometric measurement to meteorologists—information about surface temperatures on the ground, at sea level, or at the cloud tops obtained by scanning devices sensitive to energy that is invisible to the naked eye. ITOS spacecraft could return accurate day or night surface and cloud-cover images. Seven of these satellites were launched between 1970 and 1973. _TIROS_ was presented to the National Air and Space Museum by the National Aeronautics and Space Administration; _TOS_ is from the National Oceanic and Atmospheric Administration; _ITOS_ is from the Astro-Electronics Division of RCA, Inc. [Illustration: 37. Artist’s concept of ITOS weather satellite illustrating how the weather eye takes night-time (infrared) cloud-cover pictures.] Communications Satellites [Illustration: 38. Ground inflation test on _Echo 1_, the world’s first passive communications satellite.]