Summary
Highlights
Communication satellites are widely used, even if people don't realize it, from Starlink users to newspaper compilation. This video will explore the technical history of these satellites, from their original ideas to modern systems, noting that while Starlink dominates today, geostationary satellites were prevalent a decade ago. The history of satellites goes back to the 1940s.
In the 1940s, worldwide communication was limited, with telephone calls across the Atlantic relying on bouncing signals off the ionosphere, which was unreliable and had limited capacity. In the mid-1940s, Arthur C. Clarke proposed 'extraterrestrial relays' in Wireless World, envisioning large space stations in geostationary orbit (Clark orbit) to relay communications. He detailed orbital mechanics, solar power, and antenna footprints, but didn't patent his ideas.
Around the same time, others demonstrated communication by bouncing signals off the Moon. Initially, this was for ionospheric research. James Trexler of the US Navy saw a 'more insidious' use: eavesdropping on Soviet communications by reflecting signals off the Moon. This led to a project in the late 1940s, using large antennas to receive signals bounced off the Moon. By the mid-1950s, teletype signals were sent from Maryland to Hawaii via the Moon. The NSA later used this for communicating with its signals gathering ships worldwide, continuing into the 1960s before artificial satellites provided a better solution.
The first communication satellite was SCORE, launched in 1958. It converted an Atlas booster into a 'store and forward' satellite, recording data from a ground station and replaying it later. This was used for propaganda, including Eisenhower's Christmas message. SCORE operated for a few weeks before its batteries died. Courier 1B, launched later, improved on this with capabilities for thousands of words of teletype per hour, voice, and fax images. It also operated for a few weeks until a synchronization issue with its command encryption system rendered it inoperable.
Real-time communication satellites began in 1960 with Project Echo, a large, inflatable metallized sphere that passively reflected signals. This demonstrated real-time telephone calls between coasts, but required powerful transmitters and precise tracking. A less popular project, West Ford, by the US military, aimed to create a 'denser ionosphere' by deploying millions of tiny copper wires into orbit to reflect radio waves. This caused international outcry due to concerns about space debris, leading to its cancellation after three launches and influencing the Outer Space Treaty. The military eventually abandoned West Ford when more effective active repeater systems, like Telstar one, became available, paving the way for modern satellite communication.