Lunar Radio & TV Traffic
December 1961 Radio-Electronics

December 1961 Radio-Electronics [Table of Contents] Wax nostalgic about and learn from the history of early electronics. See articles from Radio-Electronics, published 1930-1988. All copyrights hereby acknowledged.

Many of Radio-Electronics magazine editor Hugo Gernsback's articles betray his penchant for writing science fiction as a sideline. That is not noted disparagingly, rather to emphasize his profound insight and vision into technology and the promises it holds for the good of mankind (and hence every other kind of ___kind). Mr. Gernsback is quick to point out in many of his editorials how he accurately predicted events and inventions occurring at later dates. This particular prognostication builds upon an earlier one regarding communications with moon-based colonies of humans. Two primary concerns are the time delays of one-way and two-way messaging (roughly 1.2 and 2.4 seconds, respectively) and the fact that the moon, while always presenting the same face toward Earth, is out of view from any given point on Earth for roughly half of each day. Accommodating the hidden moon periods would require terrestrial stations and/or orbiting satellites. When this article was written, the SCORE, Echo, and Courier satellites had been launched, but they were mostly experimental and short-lived. It was not until the following year, 1962, that the Telstar was put into orbit for active commercial relay use. History has ultimately shown that while fantastic advances have been made in terrestrial and space communications, we are still not that much closer to colonizing the moon or any planet - most notably Mars. Many scientists dismiss the moon as a practical base for humans because its lack of an atmosphere provides no protection from harmful radiation or even micrometeorites. Mars' sparse atmosphere at least gives some measure of protection.

... The Moon Poses New Problems for Electronics

By Hugo Gernsback

On May 25, 1961, President Kennedy, in a special message to Congress, officially proposed that the country - at a cost of $20 billion - send a man to the moon and back by 1970. Congress has endorsed this plan by voting a $1.7 billion budget for the space agency this year. The total US moon expenditure may reach $40 billion, particularly if the program is speeded up, which it well may be.

Since we, as well as the USSR, are now committed to the conquest of the moon (which we soon will people with our nationals), we should look ahead to the years to come.

Neither we nor the Russians are making these moon trips as pleasure excursions. Tremendous practical stakes are involved. To begin with, the moon is the best space station we may have for a long time. From it we can take off for other planets at a vastly reduced energy cost, because the moon's gravitation is only a sixth that of the earth. Thus a 1,000-ton spaceship weighs only 166 tons on the moon, and the energy to launch it into space is only one-twentieth that required on earth.

We will find the most precious and strategic metals, from platinum to beryllium, in great profusion for transshipment to earth in unmanned, radio-guided transports. Mining will be comparatively simple because of the low lunar gravity.

Most of the great optical telescopes will be on the moon where, because of the absence of an atmosphere, visibility is 100% as against 60% on earth. These telescopes will be operated by remote control from earth, and observation will be via TV and resident observers. Similar electronic means will be used for radio astronomy.

As the population of the moon increases and as industries proliferate, radio communication with the earth, spacecraft in transit and electronically guided unmanned transports will multiply at a vast rate. The moon will always depend chiefly on communication with the earth, and all such electronic traffic must be as free as possible from interruption, despite occasional solar storms and other types of interference. Solar disturbances particularly will require new evaluation of our transmitting and receiving techniques in view of our lack of experience in transmitting a dense electronic traffic to and from the moon across the 238,857-mile vacuum of space. In time it probably will be possible to augment radio and TV communication with extra-narrow-band optical-Maser type transmission and reception.

As the moon always exposes the same geographical face to the earth, which turns constantly, radio and TV transmission and reception presents a problem. Ordinarily, moon messages meant for the US could not be received 24 hours a day via direct line of sight, because parts of our western hemisphere will be invisible from the moon for 12 hours in a given day. Such messages, received in the eastern hemisphere, would then have to be relayed from there to the US. Earth messages to the moon are similarly handicapped. They will have to be relayed to a country that faces the moon or be delayed until the earth has turned around again.

Fortunately, by the time the moon is opened up, most messages will probably go via artificial earth-communication satellites which we will put up during the next few years.

While they have not been originally designed for lunar messages, there is still time to change their construction slightly so that moon traffic can be relayed to earth via the 50-odd satellites which we will put into orbit soon.

One of the slight inconveniences that man will have to put up with-probably forever - will be the time lag between earth and moon circuits. Radio waves take 1.2 seconds to bridge the 238,857 miles. Hence, when phoning to the moon, 1.2 seconds must elapse for a one-way communication to speed to its destination, and a like time for the answer - a total of 2.4 seconds. This makes for a somewhat slowed-up conversation, but will probably not be too annoying.

Delay becomes serious with a similar conversation to the planet Mars. Here the total elapsed time is 2 minutes and 10 1/2 seconds for a one-way message; 4 minutes 21 seconds for a two-way conversation. Consider also that this timing is possible only during "conjunction" of the two planets - 35 million miles. At the greatest separation, 248 million miles, the time for a two-way message would be almost 31 minutes!

Coming back to moon communications, let us also consider that the moon will be peopled not only on its always visible side as we see it from earth, but also on the far side that man never sees directly. That means that we have to take measures to relay the messages to the visible side opposite the earth. We cannot erect radio transmitters on the back side of the moon to communicate with us directly, because the signals would go out into space, never reaching the earth. Hence they must be relayed around the moon to transmitters located opposite the earth. Because there is no ionosphere on the moon, lunar radio transmissions must, it seems, rely on ground waves rather than on reflected waves. Short-range radio relay systems, or very-long-wave systems relying on ground-wave transmission, may be the answer.* This, provided that the moon's upper strata is conductive. We shall not know about this until we have actually contacted the moon, either by robot or manned craft.

Consider the technical aspects and the vastly increased quantity of all the various types of electronic transmission, which in less than 10 years will have multiplied greatly on earth. Then add a new large load to and from the moon. It becomes quite apparent that new techniques must be evoked if the interference and heterodyne problems are not to choke all electronic communication. Even today there is a great deal of chaos on many frequencies.

In addition we have the nuisance problem of "strays" or RFI-radio-frequency interference - which often plays havoc with scores of electronic instruments.

It would seem that before long entirely new means of safeguarding the transmission of radio messages, particularly long-distance signals such as those to and from the moon, will have to be invented. It presents a difficult and complex problem in electronics, but we are certain it will be solved. - H.G.

* See also "Radio on the Moon," Radio-Electronics, July 1959.

Posted January 19, 2022