We are addicted to communication satellites. These space relay stations are more active than we believe; they receive signals from the earth, filter them, change their frequencies, and amplify them before sending them to a specific place on Earth. But the first communications satellites were passive, they simply reflected the signals sending them back to a certain point on Earth. These were "Echo satellites" - the first one was launched in 1960, and the second one on January 25, 1964.
The Echo program began in 1956 as an experiment of the National Aeronautics Advisory Committee. Large balloons satellites were designed primarily to test the effects of the upper atmosphere on large lightweight orbital structures. The second application of reflective bodies in space was soon invented, by John Robinson Pierce and Rudolf Kompfner, two researchers at the AT & T telephone laboratory. Interested in using satellites for communication, they realized that Echo was a wonderful test mock passive communication. The satellite could not perform many actions, but it was an excellent tool for sending signals that could send them from one point on Earth to another. When NASA was disbanded and created by NASA, NASA became involved in the Echo project.
The first Echo satellites were designed and built by engineers at the Langley NASA Research Center. The first version was called Echo 1 (more precisely, Echo 1A, after Echo 1 was destroyed during an unsuccessful launch attempt), the ball was 100 feet in diameter, made of polyester polyester skin with a thickness of only 0,017 mm. And although he weighed only 150 pounds, only a few pounds of gas were needed in space so that he kept his form. On board were a lot of beacons for telemetry data, which were equipped with five nickel-cadmium batteries. Batteries, in turn, were charged from 70 solar batteries installed on a balloon.
Echo 1 was launched on August 12, 1960, and included a number of important innovations in the field of satellite communications. He carried out the first live satellite voice communication; delivered a radiogram to President Eisenhower; through it made the first transcontinental satellite call between two researchers; The first satellite transmitted the image. He was also one of the first satellites to experience the effects of the solar wind. Echo 1, as the sail reacted to the pressure of the solar photons that propelled it and distorted the satellite trajectory.
Echo 2 was next four years later; it is a different passive communication satellite more than its predecessor. Despite the fact that it looked like a battery-powered beacon of the telemetry system on board to provide tracking signal, monitor the temperature of the balloon material, adjust the internal pressure to maintain its shape, Echo 2 was more advanced than its predecessor in several directions. For example, it was larger than a diameter of almost 135 feet. This improved the airflow system, which meant as soon as it reached the orbit, the balloon material became smooth and it acquired a spherical shape. The second assignment of Echo 2 helped scientists gather more data on the dynamics of a large spacecraft in orbit and on the shape and size of large areas of the Earth. Echo 2 put an end to NASA research on passive communication satellites. These balls were massive compared with active communications satellites and more primitive. Echo 1 was forgotten first, after the appearance of new products in the emerging world of space communications, AT & T is developing an active communications satellite called Telstar. Echo 1a was re-launched on May 24, 1968. Echo 2 was next June 7, 1969.
