April 1961 Popular Electronics
of Contents]People old and young enjoy waxing nostalgic about and learning some of the history of early electronics.
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late 1950s and early 1960s were the dawn of the Space Age, beginning
unofficially with the launch of Sputnik. Popular Electronics
put a lot of effort into educating the public on advances in space electronics,
including not just the spaceborne platforms, but also ground tracking
and communicating equipment. Much hardware was launched into orbit in
the early years without giving much thought to the hazards or space
debris. Failures in the form of explosions scattered chunks widely,
but fortunately most were low enough to have their orbits degrade and
re-enter the atmosphere. One interesting tidbit reported in this article
that I didn't know was that the TV camera lens on the
weather satellite was defocused during launch (due to positional shifting
from vibration and G forces, I suppose) and crippled the image quality
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Have you ever stopped to think where our satellite program would
be without electronics? The answer obviously is "nowhere." Without radio
signals, for example, our satellites would be big chunks of scrap metal
floating around in space.
The National Aeronautics and Space Administration has proposed
sending seven spacecraft to the moon in 1963 - 1965. Given the
code name, "Surveyor," these fully automatic satellites will
soft-land on the moon and send back TV pictures of the surface.
They will also conduct a number of other experiments to determine
the content and texture of the lunar surface. The model shown
here was developed by Hughes Aircraft.
As this column goes to press, a Juno II is being readied at
Cape Canaveral. The payload is now called NASA S-45, but if
the shot is successful it will become Explorer X. Destined to
study the ionosphere, this unusual satellite will transmit on
six different radio frequencies. The ring antenna will be used
on the lower frequencies - it is designed to unfold after separation
from the fourth stage.
These Soviet radio-telescope antennas are located in the Caucasus
Mountains. Similar antennas are probably used to operate the
telemetering transmitters on LUNIK IV.
One method of satellite tracking. General Electric's optical
tracker using a high-power telescope and special TV image pickup
Another method of satellite tracking. The new 33·element helical
beam antenna at Wallops Space Flight Station.
Only the rocket engines and propellants outrank electronics in importance.
But even this is questionable - for without electronic guidance a rocket
would never get to the right place at the right time. And, even it it
did, how would we earthlings know it?
In short, without electronics,
there could be no space program. Recognizing this "truth," the editors
of Popular Electronics plan to devote several pages each month to Space
Can anyone hear satellites? This is the question
most frequently asked by SWL'ers, experimenters, hams, and novices in
space science. The answer is a very simple "yes." Many satellite signals-both
American and Soviet - have been heard by curious listeners. In fact,
as we shall show in one of our forthcoming columns, SWL-type verifications
have been issued for about ten satellites.
The Soviet satellite
signals have been consistently easier to intercept. All of the Lunik
and Sputnik satellites have had at least one transmitter operating within
plus or minus 20 kilocycles of 20 megacycles (19.98 mc.-20.02 mc.).
The listener need only spot the 20-mc. broadcast from Station WWV on
the dial of an average short-wave receiver. He can then sit back and
wait, for some time within the following two hours he will have a good
chance of hearing a Soviet satellite.
Most listeners have been
distressed to find that practically all of the American satellites transmit
on frequencies near 108 megacycles. The power radiated by them has been
low, generally less than 1/2 watt. However, many experimenters and radio
amateurs, using modified FM converters and simple two- or three-element
beams, have been able to verify American satellite radio transmissions.
Radio Signals from the Satellites
Satellites are listed in the order launched. Explorer
X had not been launched at press time. but is included because of number
and variety of frequencies to be employed. Asterisk indicates that this
is the beacon transmitter frequency.
But the listener
must know when to listen and what to listen for. It is impossible in
this first installment to discuss all the ways and means of knowing
when to listen. Simplified methods are available to permit satellite
tracking -when one or two check positions and the date and time of the
launching are known. These methods will also be discussed in detail
in one of our forthcoming columns. In the meantime, the table at left
contains information on the frequencies and radiated power of the satellites
known to be in orbit and transmitting as of February 20, 1961.
FM/TV DX Reflections.
The 100-foot balloon (called
Echo I) that is now circling our globe presents another possibility
for DX'ing the FM/TV bands. Using the same principle as the Bell Telephone
Laboratories in communicating between Holmdel, N. J., and Goldstone,
Calif., that is, ignoring the earth's ionosphere and bouncing the signal
off the satellite, a DX'er may be able to catch rare FM and TV signals.
The DX'er should spot his receiver on an unoccupied channel
and await a satellite passage. As the satellite approaches overhead,
midway between the distant transmitter (say 1000-2000 miles) and his
receiver, there should be a "burst" of signal. Under average conditions
it would not be unreasonable to expect to hear 25-30 seconds of an FM
or TV signal - certainly enough during station break time for identification
Radio amateurs have not been able to use Echo I consistently
because of the relatively weak power they are permitted to radiate.
Even with highly directive antennas, their "effective radiated power"
is always under 50,000 watts. Many TV and FM transmitters, on the other
hand, are operating with an "effective" power above 350,000 watts. If
the FM/TV DX'er uses a modest beam of only 6-db gain, however, he can
work with "effective" powers near 1 megawatt! "Passive"
Although there is much to be said for the "active
satellite" which receives and transmits like a miniature relay station,
many scientists are convinced that passive reflecting satellites have
a definite place in the U. S. space program. The National Aeronautics
and Space Administration (NASA) has plans to orbit another Echo-type
balloon with about twice the reflective power of Echo I. This extra
gain will result from increased size and reflectivity of the Mylar-aluminum
Another line of thought concerning the Echo-type
balloon is that such passive communication satellites should be anything
but spherical reflectors. The U. S. Air Force has been studying unusual
passive satellite designs that would be "100 times" more efficient in
reflecting power than Echo I. It is interesting to note that if the
latter experiments prove successful, FM and TV DX will become rather
commonplace. Space Facts.
The Missile and Space
Vehicle Department of the General Electric Company is currently distributing
a comprehensive booklet on space data. Entitled "Space Facts," this
64-page booklet is jam-packed with figures, tables, and charts on the
earth's atmosphere (how much, how far into space, etc.), the physics
of space flight ( orbit decay, thrust, re-entry problems, etc.), and
bioastronautics (acceleration, impact, etc.).
One section is
devoted to space communications, and shows the eight basic means of
earth-to-space vehicle or satellite-to-satellite radio links. Distant
range of one-way communication may be calculated from a fold-out table
bound in the booklet.
Space Facts is really a handbook written
for technicians and engineers who need basic information at their finger-tips.
Offered free (write Space Facts, Missile & Vehicle Dept., General
Electric Co., 3189 Chestnut St., Philadelphia 4, Pa., Att. Mr. J. Hoffman),
it will undoubtedly be in short supply. First come - first served.
One of the many disappointments
due to the failure of Pioneer VI (the projected lunar probe that exploded
70 seconds after launching on December 15, 1960) was the fact that a
General Electric satellite tracking device had no chance to be tested.
An optical tracker using a special TV camera tube attached to a high-power
telescope, this G. E. system is so sensitive that it can take movies
at night using only starlight. Following Pioneer VI to a lunar orbit
would have been roughly equal to spotting something the diameter of
a dime at a distance of 2500 miles!
transmitters aboard TIROS II may be inactive by the time this column
is in print - original plan for battery life was about 4 months, and
TIROS II was launched on November 23, 1960. Both wide and narrow-angle
TV camera lenses were present in the TIROS II, but the wide-angle TV
lens was defocused during launching and only 86% (9524) of the photos
relayed to earth are proving useful for weather analysis. Although the
narrow-angle TV transmitter performed excellently, the photos are of
comparatively little value without the orientation obtainable with the
wide-angle lens. TIROS II also used a simple magnetic system to control
the satellite spin axis, enabling ground observers to change the angle
of the axis in space. The system was developed by RCA in cooperation
with NASA. "In short, my plan is to
develop the XM-7 rocket
ourselves, launch it in 18 months, and claim
in the name of the Meredith Aircraft Corporation."