We rely on communications satellites for a lot of modern conveniences, but they didn’t exist until the mid-twentieth century. This Week in Rocket History is the story of the first practical active communication satellite, Telstar 1.

Telstar 1 launched on July 10, 1962, on a Thor-Delta rocket from LC-17B at Cape Canaveral Air Force Station in Florida. The satellite was launched into a highly eccentric orbit between about 1,000 kilometers to about 6,000 kilometers inclined just under 45 degrees to the equator. Telstar 1 was built for AT&T as part of a multinational agreement among AT&T, Bell Telephone Laboratories, NASA, BPO in the United Kingdom, and the National PTT in France.

Telstar 1 was a 77-kilogram spin-stabilized satellite that used fixed orientation solar panels. It had only one transponder, compared to the dozens found on modern communication satellites, and that transponder was relatively low power – only 2.25 watts – while it transmitted over very long distances.

There were three ground stations supporting Telstar 1: One in Andover, Maine; one in Goonhilly Downs in the UK; and one in Pleumeur-Bodou in France.

The U.S. and French ground stations that communicated with the satellite each had a massive dish that was over 50 meters in diameter and weighed about 450 U.S. tons. The Goonhilly Downs station in the UK was a much smaller dish, measuring 26 meters in diameter. This smaller design, which used a parabolic dish, was the model on which all subsequent satellite dishes were based. Modern satellite dishes are small enough to be put into planes.

To save time, Telstar used frequencies already being used by line of sight microwave relays. Signals sent up to the satellite were modulated when the satellite sent them back, mainly to reduce the power needed and also prevent feedback interference. However, this required more bandwidth, an acceptable tradeoff for the first generation satellite that would be improved in subsequent satellites.

Telstar accomplished many historic firsts, including the first live television transmission between the United States and several European countries. The broadcast was only thirty minutes long due to the limited time the satellite was in view of both ground stations at the same time. Also, the picture quality wasn’t very good, but that was understandable under the circumstances.

Telstar 1 also included two scientific instruments which measured high-energy protons and high-energy electrons in the Van Allen radiation belts.

The satellite functioned for seven months before succumbing to radiation damage to its components caused by the Starfish Prime high-altitude nuclear test that created a human-made radiation belt at 400 kilometers altitude. This test was ironically the day before Telstar 1 launched. Oops.

To date, there have been 23 Telstar satellites launched to orbit, including the first one. Telstar 2 was basically identical to its predecessor but functioned for much longer. It was turned off in 1965, two years after launch, with no major problems. All of the following Telstars, starting with Telstar 301, launched twenty years later, have been placed in geosynchronous orbit, and they have become increasingly larger. The most recent Telstar 19V satellite is the biggest communication satellite ever launched — 92 times more massive than Telstar 1.

As of early July 2022, Telstar 1 is still in orbit.

More Information

Telstar 1 mission page (NASA)

An Introduction to Satellite Communications (Google Books)

July 12, 1962: The Day Information Went Global (NASA)