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Echo 1Echo 1

the world's first communications satellite capable of relaying signals

The satellite now commonly known as Echo 1 was actually formally named Echo 1A. The original Echo 1 was destroyed on May 13, 1960, after a failure in the rocket designed to launch the giant ball into space. Echo 1A (Echo 1) was launched from Cape Canaveral on August 12, 1960.

Essentially a giant balloon, Echo I was made of a 31,416 square-foot sheet of Mylar plastic film only 12.7 microns thick, or roughly one-tenth the width of a human hair. That sheet was covered smoothly with 4 pounds of reflective aluminum coating. A set of 107.9-MHz beacon transmitters were carried for telemetry. The transmitters were powered by five nickel-cadmium batteries that were charged by 70 solar cells mounted on the balloon. Instrumentation included temperature sensors to monitor the balloon's skin temperature and pressure sensors to monitor the balloon's internal pressure. A beacon system, consisting of two transmitter assemblies, provided tracking and telemetry signals. Total weight was just 132 pounds. With a diameter of 100 feet, Echo 1 could actually be seen by the naked eye over most of the Earth, proving brighter than most stars.

When tested on the ground (picture), Echo 1 was inflated by use of a blower connected to the satellite by a hose, using 40,000 pounds of air. It was sent into orbit folded flat and then inflated. It took 40,000 pounds of air to inflate the "satelloon" on the ground, but only several pounds of gas once in orbit. To keep the sphere inflated in spite of meteorite punctures and skin permeability, a make-up gas system using evaporating liquid or crystals of a subliming solid were incorporated inside the satellite.

Echo 1 was not the first satellite to broadcast a message from space, as a a recorded Christmas greeting from President Dwight Eisenhower was transmitted in December 1958 during the Project SCORE satellite test. It was, however, the first to facilitate two-way, live communications. It accomplished this by essentially serving as an enormous mirror 10 stories tall that could be used to bounce communications signals off of. Echo 1's surface was used to reflect 960 and 2390 Mhz signals. Among Echo 1's many contributions was the first live voice communication via satellite, delivered by President Eisenhower himself. The first coast-to-coast telephone call using a satellite was also made with Echo 1, from one researcher to another as a test, as was the first image transmitted via satellite, a portrait of Eisenhower. Echo 1 also provided data for the calculation of atmospheric density and solar pressure due to its large area-to-mass ratio.

To communicate with Echo 1, Bell labs created a 50-foot, horn-shaped antenna. Later, while calibrating the antenna, radio astronomers Arno Penzias and Robert Wilson detected cosmic microwave background radiation, the first solid evidence of the Big Bang, for which they won the Nobel Prize

The spacecraft proved remarkably durable, surviving a meteor shower. It proved susceptible to sunlight, however, which could shove it around enough to push it back into Earth's atmosphere. It burned up on re-entry on May 24, 1968. Echo 2, which had been launched in 1964, burned up in the atmosphere on June 7, 1969. By then NASA had begun using satellites that could actively transmit data, rather than passively reflect signals.

Encyclopedia Astronautica

President Dwight Eisenhower

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This page was last updated on 06/30/2015.

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