Everyone knows the story well: Sputnik reached Earth's orbit in October 1957. Nine months later, NASA was officially created, and in October 1958 it launched its first satellite, the lunar orbiter Pioneer 1. Space technology has advanced a lot since then, and satellites play a vital role in global telecommunications. With that said, what was NASA's first communications satellite? Actually, there were two, under the so-called Project Echo. Your eyes don't deceive you: the agency built a pair of giant balloons made of Mylar, with a diameter of 30 meters in the smallest design.
The Origins of Communications Satellites
Exploring the history of communications satellites isn't a simple process. If we have to talk about the original concept, all roads lead to Arthur C. Clarke and his article Extraterrestrial Relays published in the British magazine Wireless World in October 1945. Pioneer 1 was NASA's first satellite and the first to relay communications, but technically it was a lunar orbiter. Two months after Pioneer 1, SCORE, Signal Communications by Orbiting Relay Equipment appeared, which many consider the first real communications satellite in the world. However, that project was under the jurisdiction of ARPA/DARPA due to its secret profile (only 88 people knew of its existence). Finally, we arrive at the Echo communications satellites, the first of that kind under NASA's wing, and the first designed with signal relay as a priority. Now, there was a small detail...
The Echo Satellites: Giant Balloons
… they were giant balloons! The Echo satellites acted as passive reflectors, bouncing microwave signals to send them to another region of the planet. Technically, Echo 1 was actually Echo 1A because the original model launched on May 13, 1960 ended up in the Atlantic Ocean due to a Thor-Delta rocket failure. Echo 1A had its revenge three months later, on August 12 precisely, and remained in orbit for almost eight years, doubling the time estimated by experts. Echo 1A measured 30.5 meters in diameter and was made of reflective BoPET, a material we know commercially as Mylar. Ground inflation tests demanded 18,000 kilograms of air, but at launch its mass barely exceeded 71 kilograms (including 15 kg of sublimation powders as part of the inflation system).
Echo 2: Bigger and More Rigid
Echo 2 arrived in orbit on January 25, 1964, with some important differences. First, it was larger than Echo 1, with a diameter of 41.1 meters. Second, the skin of Echo 2 (a combination of Mylar trapped between layers of aluminum) had rigidization capability, meaning it didn't need constant internal pressure to maintain its shape. This advantage allowed the agency to simplify the inflation system and offer greater resistance to microimpacts, without sacrificing the smoothness or integrity of the sphere. Available data put Echo 2's total mass at 256 kilograms, and after more than five years of space adventure, it made its final reentry on June 7, 1969.
Source: Damn Interesting
