Telstar-1: First Communications Satellite 50 Years Ago

Posted by Sam Churchill on

Bell Labs today is marking the 50th anniversary of the launch of Telstar I — the first active communications satellite.

Telstar I incorporated dozens of innovations from Bell Labs, including the transistor and solar panels, and was powered by 3,600 solar cells, also invented by Bell Labs in 1954.

The satellite was built by a team at Bell Telephone Laboratories, including John Robinson Pierce, who created the project; Rudy Kompfner, who invented the traveling wave tube transponder used in the satellite; and James M. Early, who designed its transistors and solar panels. Telestar produced 14 watts.

Telstar 1 relayed its first, and non-public, television pictures — a flag outside Andover Earth Station – on July 11, 1962. The satellite could carry 600 voice calls and one black-and-white TV channel from an elliptical orbit. The orbit allowed a maximum transmission time between Europe and the United States of 20 minutes per pass.

Telstar 1 became a victim of the Cold War. The day before Telstar 1 was launched, the United States had tested a high-altitude nuclear bomb (called Starfish Prime) which energized the Earth’s Van Allen Belt where Telstar 1 went into orbit. This vast increase in radiation, combined with subsequent high-altitude blasts, including a Soviet test in October, overwhelmed Telstar’s fragile transistors; and it went out of service in early December 1962. Detectors on Telstar were used to measure distribution of the radiation produced by the tests.

Telstar 1 and 2 are still in orbit as of May 2012, according to the US Space Objects Registry. Subsequent Telstar satellites were geosynchronous spacecraft that share only their name with Telstar 1 and 2.

By contrast, EchoStar XVII, a geosynchronous broadband satellite launched over the United States last week, measured 85.5 ft, outputs 16 kilowatts, weighed 6,100 kilograms (13,000 lb), and will deliver more than 100 Gigabit of throughput, connecting to home satellite dishes at 10 Mbps.

Satellites remain constrained by satellite bandwidth. Commercial satellites often use the Ka band (20/30 GHz) or Ku band (11/14 GHz). While the latest high throughput satellites may offer up to 100 Gbps throughput, transoceanic fiber can top them by a factor of 100 – with some 10 Terabit/sec capacity now available on four fiber strands.

Intelsat is the world’s largest satellite operator with a fleet of over 50 geostationary satellites, while SES is the 2nd largest, with a fleet of 51 geostationary satellites.

Posted by Sam Churchill on Monday, July 9th, 2012 at 11:37 pm .

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