The First Commercial Satellite

First Commercial Satellite

The first undersea communications cable connecting Europe and North America was laid in 1858 by Cyrus West Field. The trans-Atlantic section of cable began in Ireland and ended in Newfoundland. It initially carried telegraph messages and remained functional for three weeks.

The first transatlantic telephone cable system went into service in 1956 with 36 independent channels. By 1965, four cables with a combined 360 telephone lines would connect the two continents.

At this time over 90% of American households owned a television. But a reliable television signal had yet to be transmitted across the Atlantic Ocean. To transmit video across the Atlantic with conventional ground based radio waves would require a tower 400 miles high, since they cannot transmit around the curvature of the Earth. Telephone lines could have been used, but one telephone line can only transmit 4 KHz of bandwidth, nowhere near the 6 MHz required for the most basic video signal. A better solution was needed.

The Moon

When light waves (visible or invisible) intersect solid objects, they are reflected. And it just so happened that there was a rather large solid object orbiting the Earth. By 1945 the first serious plans to use the Moon as a signal reflector began as an attempt to monitor Soviet radar signals during the Cold War.

It was soon realized that the Moon could also be used to relay communication signals. A link was successfully created between Washington D.C. and Hawaii which transmitted messages for almost a decade. This technique is referred to as passive signal relay. Balloons were later launched to an altitude of 1000 miles on a Thor-Delta rocket in a mission named Project Echo, and aslo successfully reflected signals.

Telstar

Relying on passive signal reflections ultimately gives a very limited solution to transmitting communications around the globe. For satellite communications to truly make an impact, it was necessary to build a device that could receive signals and amplify them in space before sending them back to Earth.

The first satellite of this kind was a 17 pound, 34in diameter spherical shaped craft called the Telstar I. It was conceived by the Bell System in July of 1960. The sphere had two rings of cavity antennas, one to receive signals at 4 GHz and the other to transmit signals back to Earth at 6 GHz. The rest of the craft was covered with solar cells. The amplification of signals was done with a Traveling Wave Tube, a type of vacuum tube. Thus the first active communications satellite was fundamentally analog.

On July 10, 1962, the world's first active communications satellite, Telstar I, was launched ontop of a Thor-Delta rocket from Cape Canaveral. The craft was rotationally symmetric and spin stabilized in order to maintain its orientation attitude towards Earth, because it lacked thrusters or inertia wheels needed to do so.

Three ground stations communicated with Telstar using 177ft horn antennas housed in 14 story tall structures, one in Maine, and two in Europe. These antennas had to be aimed at the satellite with accuracy greater than 0.06 degrees.

On July 23, 1962, the Telstar relayed the first live transatlantic television signal which was aired simultaneously by Eurovision in Europe and all three major networks in the United States. After a short clip of a baseball game, President Kennedy made some statements.

President Kennedy on Telstar

source: NASA Video

Telstar I was a remarkable success. Transmissions were better than expected, solar cells worked exactly as planned, and tracking of the satellite by ground stations was almost routine. Clocks in Europe and America were syncronized to an accuracy within one microsecond.

Starfish Prime - High Altitude Weapons Test

Telstar I construction Van Allen Belts. photo credit: NASA

Telstar operated flawlessly for 7 months until an unusual manmade event caused severe damage to the spacecraft. In 1957, a physicist at Lawrence Livermore National Laboratory named Nicholas Christofilos examined the possibility that a nuclear detonation in space would create an artificial radiation belt in the upper regions of the Earth’s atmosphere.

Naturally occurring belts of electrically charged particles above the Earth had just been discovered by Explorer I, the first satellite launched by the United States in early 1958. These particles, named the Van Allen belts, in honor of the man who directed the experiment that discovered them, consist of high-energy electrons and protons ejected from great solar flares that are caught in the Earth’s geomagnetic field.

Christofilos theorized that a nuclear detonation several hundred miles above the Earth could produce a shell of trapped radiation in the upper atmosphere, oriented along the Earth’s magnetic field, like the Van Allen belts. The theory was of extreme interest to the United States government, particularly the Department of Defense, for the possibility that an artificially created radiation belt might affect defense systems, including degradation of radio and radar transmission and damage or destroy ballistic missile warheads entering the belt. Furthermore, the theory predicted that if a radiation belt was created originating above the Indian Ocean, it would knock out radar stations at similar northern latitudes within the Soviet Union.

The first high altitude nuclear test was performed in the south Atlantic Ocean on August 27, 1958, named Operation Argus. James Van Allen described these tests as "the greatest geophysical experiment ever conducted." Further high altitude nuclear testing was carried out in the Pacific Ocean under an operation named Starfish Prime. On July 9, 1962, a 1.4 megaton nuclear weapon was detonated above Johnson Atoll, 700 miles west of Hawaii, at an altitude of 250 miles.

Operation Starfish Prime

In Hawaii, the resulting electromagnetic pulse destroyed hundreds of street lights, and damaged telephone links between the islands. The resulting artificial radiation belts were 100 times greater than expected and traveled to altitudes greater than 4,000 miles.

Effects on Earth Orbiting Satellites

Radiation gradually damaged solar cells and transistors on the Telstar. By November of 1962 the command channel was mostly not responding. Engineers were able to make it fail in a way that it continued to relay transmissions. Ultimately the spacecraft failed completely on February 21st of 1963. Satellites of this time were built with timers designed to disable transmitters after a prescribed amount of time to prevent old or failed satellites from consuming radio frequencies indefinitely. Telstar was successfully shut down, however it continues to orbit to this day.

1962 Satellite Orbits Various Satellite Orbits

Artificial radiation belts resulting from Starfish Prime lasted for over three weeks and destroyed one third of existing satellites, including Telstar and the United Kingdom's first satellite, the Ariel 1.

As successful as Telstar was, its greatest limitation was its elliptical orbit. Telstar could only relay messages for a few hours before moving out of range of ground stations. On April 6, 1965, Intelsat I became the first commercial communications satellite with a geosynchronous orbit, providing uninterrupted active communications relays for its entire lifespan. And a mere four years later, live video was transmitted from the moon during the Apollo 11 mission.


Originally published

Sources:
  The Conquest of Space by
  Significant Achievements in Space Communications and Navigation, 1958-64 by
  
   Contributed by: Milton B. Punnett, P.E. (Ret.)
  
  NASA:
    
    
    
  Nuclear Tests:
    
    
    
    
  Video:
    
    
    
  Further Reading:
     by James Bickford

Wreath

connect Follow Classic History on Pinterest Follow Classic History on Facebook Instagram youtube

Sign up for email updates.

Welcome new readers!

In a hope to share any interesting historical stories I come across in the future I will be writing and posting articles whenever I can. Hopefully quite often.

I'll also be keeping you up to date on any good reads I come across in the Recommended section.

Looking for something in particular? Find it more quickly on the Search page.

And here is a complete list of all articles since the beginning.

H. G. Wells Portrate

"It is possible to believe that all the past is but the beginning of a beginning, and that all that is and has been is but the twilight of the dawn."

~

The Discovery of the Future


 Conquest of Space
Link - Commissions Earned

Share



The First Commercial Satellite
Comments:

  • Justin
    2020-02-05
    Interesting article. An enjoyable read. Thanks
  • Wake
    2020-02-11
    Glad you enjoyed it!
  • If you would like to leave a comment or a reply, please answer this security question: