Wireless Systems Design

Sputnik: Golden Anniversary

How satellites changed wireless and changed our lives in the process

It was 50 years ago October 4th that the first successful satellite was put into orbit. Launched by the Russians, this satellite called Sputnik, as basic as it was, set off a stream of events that could not have been anticipated. Besides starting the space race, launching the satellite industry, revolutionizing the telecommunications business, and intensifying the cold war, this satellite had so many unintended consequences, good and bad, it is hard to identify all of them. Fifty years is not that long in the overall scheme of things but a great deal has happened in that time, thanks to satellites. And think of this: what good is a satellite without wireless?

Sputnik I

In the mid-1950s the International Council of Scientific Unions decided to launch artificial satellites during the International Geophysical Year to study space. The U.S. solicited proposals for a satellite and was on its way to building Vanguard, a 3.5 pound satellite as a starter. But before that program could get off the ground, literally and figuratively, the Russians surprised everyone with their Sputnik I on October 4, 1957.

Sputnik I was a 22.8 inch in diameter ball weighing 184 pounds. It was put into an elliptical orbit with an apogee of about 587 miles and a perigee of about 150 miles. It had a period of 96 minutes. Sputnik did not do much other than transmit signals back to earth with temperature, pressure and other basic telemetry data. It had two transmitters, one transmitting on 20.005 MHz and the other on 40.002 MHz. The 20.005 MHz signal was easily received by anyone with a shortwave receiver so millions of people heard it, especially hams that had receivers. I remember listening to it myself on an old Hammerlund HQ-150 receiver. Pretty impressive. But to really show the world what it could do, Russia launched Sputnik II just a month later on November 3, 1957. This one included the dog Laika. Remember that?

Well there is nothing like competition from some one like Russia who was perceived to be our enemy to kick-start the U.S. into action. The disastrous (literally) Vanguard program was canceled and a new satellite program was initiated in record time. Called Explorer, the first satellite was launched on January 31, 1958. Pretty impressive follow up. Can we still do that? I'm not so sure, especially if Congressional approval is needed. In just 84 days, thanks to Cal Tech, JPL, and Dr. Werner Von Braun, a Jupiter C rocket was modified and the satellite was built and successfully launched.

The Explorer I satellite weighed 30.66 pounds and was put into an elliptical orbit with an apogee of 1575 miles and a perigee of 224 miles. It transmitted data back to earth with a 60-mW transmitter on 108.03 MHz and a 10-mW transmitter on 108 MHz. This satellite was instrumented by Dr. James Van Allen to monitor cosmic rays. But ultimately his efforts lead to the discovery of the bands of charged particles trapped by the earth's magnetic fields, now called the Van Allen belts. Anyway, this satellite and the Sputniks had a very short life because once the batteries failed they were essentially useless and they quickly burned up in the atmosphere. Which lead us to realize that satellites and wireless were meant for one another.

Satellite Development

The fact that the Russians could put a satellite into orbit meant that they could probably shoot an A-bomb our way any time they wanted. This started a flurry of activity in political, military, technological, scientific, educational and other developments. All positive. And this event was also lead directly to the establishment of the National Aeronautic and Space Administration (NASA) in July 1958. And the rest, as they say, is history.

Other significant developments have come over the years. We got the first real communications satellite in 1962. Remember Telstar? It was one of the first spin stabilized satellites and one of the first to use solar cells for recharging and a traveling wave tube (TWT) amplifier. It operated with a 6-GHz uplink and 4-GHz downlink. It had a polar orbit about 7000 miles up. To be effective in full communications, a whole constellation of these satellites was proposed but this expensive idea was abandoned.

One of the biggest discoveries and most important developments is the geostationary satellite. If you put a satellite into orbit about 22,300 miles out orbiting around the equator, it will rotate in perfect synchronization with the earth and therefore appear fixed overhead. With that satellite in place, you can use it as a radio relay station by transmitting an uplink signal to the satellite then translating the signal to another frequency transmitting it back to earth on a down link to some other desired place.

The concept was first proposed by Sir Arthur C. Clarke, a British author and inventor. He talked about "extra-terrestrial relays" being used for telecommunications in the October, 1945 issue of the British magazine Wireless World. He showed how a minimum of three geostationary satellites could give worldwide radio coverage. And he was right. But it was not until 1963 when the first successful geosynchronous satellite was put into service. That satellite called Syncom 2 was used in the world's first relayed telephone call. Syncom 3 came along in 1963 and was used in 1964 to carry the Tokyo Summer Olympics on TV. Another first.

Later, we actually landed men on the moon in July of 1969. Then came things like the Shuttle, the Hubble telescope, and the International space station. And Voyager was sent to Mars and beyond.

Radio was the great invention but satellites gave it a whole new dimension. Microwaves, which hardly travel any distance at all on Earth, can travel tens of thousands of miles in space, and therefore be routed anywhere. Just take a look at what satellites have given us:

· Worldwide long distance telephone calling.

· Video distribution

· Data relays

· Surveillance

· Satellite TV (Direct TV, Dish network, etc)

· Satellite radio

· Satellite navigation (GPS, GLONASS, Galelio)

· Satellite cell phones (Iridium, Globalstar)

· Space exploration, research and monitoring

· Military, defense, etc.

Even amateur radio operators have built and launched satellites for use in their informal communications.

It is amazing really how much satellites contribute to our life. But they are hugely expensive and so vulnerable. They must offer a very large return on their investment to justify, for sure. And their limited life makes them useless after 10 years or less. And if that's not vulnerable enough, today technology exists, thanks to a recent Chinese demonstration, to shoot a satellite down with a missile. Nevertheless, let's congratulate and salute the Russians who really got the whole thing going in a big way.

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