V2 for Ionosphere Research?
ONE of the most important branches of radio physics is ionospheric research and until now all our knowledge of conditions in the ionosphere has been deduced from transmission and echo experiments. One of the more modest claims of the British Interplanetary Society was that rockets could be used for very high altitude investigations and it will not have escaped your readers' notice that the German long-range rocket projectile known as V2 passes through the E layer on its way from the Continent. If it were fired vertically without westward deviation it could reach the F1 and probably the F2 layer.
The implications of this are obvious: we can now send instruments of all kinds into the
ionosphere and by transmitting their readings back to ground stations obtain information which could not possibly be learned in any other way. Since the weight of instruments would only be a few pounds - as compared with V2's payload of 2,000 pounds - the rocket required would be quite a small one. Its probable take-off weight would be one or two tons, most of this being relatively cheap alcohol and liquid oxygen. A parachute device (besides being appreciated by the public!) would enable the rocket to be re-used.
This is an immediate post-war research project, but an even more interesting one lies a little further ahead. A rocket which can reach a speed of 8 km/sec parallel to the earth's surface would continue to circle it for ever in a closed orbit; it would become an "artificial satellite." V2 can only reach a third of this speed under the most favourable conditions, but if its payload consisted of a one-ton rocket, this upper component could reach the required velocity with a payload of about 100 pounds. It would thus
be possible to have a hundred-weight of instruments circling the earth perpetually outside the limits of the atmosphere and broadcasting information as long as the batteries lasted. Since the rocket would be in brilliant sunshine for half the time, the operating period might be indefinitely prolonged by the use of
thermocouples and photo-electric elements.
Both of these developments demand nothing new in the way of technical resources; the first and
probably the second should come within the next five or ten years. However, I would like to close by mentioning a possibility of the more remote future - perhaps half a century ahead.
An "artificial satellite" at the correct distance from the earth would make one revolution every 24 hours; i.e., it would remain stationary above the same spot and would be within optical range of nearly half the earth's surface. Three repeater stations, 120 degrees apart in the correct orbit, could give television and microwave coverage to the entire planet. I'm afraid this isn't going to be of the slightest
use to our post-war planners, but I think it is the ultimate solution to the problem.
ARTHUR C. CLARKE,
British Interplanetary Society.
There was a follow-up article, written at about the same time as the letter, but not published until October of the same year. Someone has scanned in the article and placed it at: Extra-Terrestrial Relays, subtitled: Can Rocket Stations Give World-wide Radio Coverage?