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
TIROS 2 weather satellite was defocused during launch (due
to positional shifting from vibration and G forces, I suppose) and
crippled the image quality severely.
April 1961 Popular Electronics
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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.
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?
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
Another method of satellite tracking. The new 33·element
helical beam antenna at Wallops Space Flight Station.
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 Electronics.
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.
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" Satellites. 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 foil surface.
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.
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,
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.
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.
Briefings. 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
ourselves, launch it in 18 months, and claim Mars
the name of the Meredith Aircraft Corporation."
Posted November 6,