The experiment initiated from Project Echo, which was the first passive communications satellite experiment. There were two aircraft launched, one in 1960 and the other in 1964. Both aircraft were metalized balloon satellites that were designed to reflect microwave signals. Additionally, after coming in contact with the satellites, communication signals bounced off them from one point on earth to another.
Let us now talk about both Echo 1 and Echo 2 to see how they managed to change the course of history.
Initially, NASA’s Echo 1 was built by a company in Northfield, Minnesota, known as G.T. Schjeldahl. The balloon satellite was designed to be a reflector rather than a transceiver. It was then placed in a low orbit of the earth. Upon sending signals, they would bounce off its surface and return to earth. Furthermore, when NASA was conducting ground inflation tests, 18,000 kg of air was required to fill the balloon. However, in orbit, the situation was completely different. While in orbit, the satellite required not more than a few pounds of gas to keep itself inflated.
If the satellite was to be placed in the orbit, it needed to be protected against punctures caused by asteroids. Therefore, to keep the satellite inflated, NASA came up with a make-up gas system using evaporating crystals or liquid of a subliming solid. This was incorporated inside the satellite so that it does not get completely knocked out from a hit by a meteorite.
The first attempt by NASA to orbit an Echo satellite failed when Echo 1 lifted off from Cape Canaveral’s LC-17A. Although the Thor stage performed properly during the coasting stage, the altitude control jets on the Delta stage failed to ignite. The Echo 1 was a 30.5-meter diameter balloon, which was made from a 0.5-mil-thick biaxially oriented PET film, which was metalized at a thickness of 0.2 micrometers. Furthermore, the total mass of the satellite was 180 kilograms and was used to redirect both intercontinental and transcontinental radio, telephone, and television signals.
Moreover, Echo 1 also featured 107.9 MHz telemetry beacons that were powered by five nickel-cadmium batteries, charged 70% by solar power mounted on the balloon. Since the surface of Echo 1 was shiny and reflective, it was clearly visible to the naked eye at different points on earth.
Following Echo 1, Echo 2 was a 41.1 diameter balloon satellite, which was the last satellite launched under Project Echo. Echo 2 featured an improved inflation system to make it smoother and enhance its sphericity. As compared to Echo 1, the skin of Echo 2 was rigidizable. Therefore, this allowed the satellite to maintain its shape and pressure without using constant internal pressure. Not only a long-term supply of inflation gas was not required, but it was also easily able to survive strikes from micrometeoroids. Echo 2, as compared to Echo 1, was larger. It was visible at different points on earth to the naked eye. Furthermore, Echo 2 was designed for a slightly different purpose as well. It was used to investigate the global geometric geodesy and the dynamics of large spacecraft.
In 1960, the USA’s space agency NASA launched a balloon-shaped satellite, Echo-1 (photo, below). It took up an orbit comparatively close to Earth, about 1600 kilometers up. Once in position, it grew to a diameter of 30 meters (100 feet), by inflating its own balloon made of a plastic material called Mylar. The Mylar had a reflective coating of aluminum. Radio signals beamed from Earth to Echo-1 bounced off the Satellite’s surface and could be received on the Earth far from the original transmission.
NASA’s Echo-1 successfully transmitted voice, music and pictures between the USA and Europe, but in 1968, it disappeared from the sky.
The Echo satellite program played a crucial role in providing accurate astronomical reference points, which helped to locate Moscow. This improved accuracy was brought by the U.S. military, which used the same technology for its intercontinental ballistic missiles.
Project Echo (Wikipedia)