July 1957 Radio & TV News
of Contents]These articles are scanned and OCRed from old editions of the Radio & Television
News magazine. Here is a list of the
Radio & Television News articles
I have already posted. All copyrights are hereby acknowledged.
Here is a great look inside the planning and operation of the "Minitrack"
systems used for
Project Vanguard to track the Sputnik, Echo, Explorer, and other
early Earth artificial satellites during the
Geophysical Year (IGY) activities. "Essentially, the [IBM 704's]
storage function works by means of doughnut-shaped cores, about the
size of pinheads, which are strung on a complex of wires in such a way
that several wires pass through each core. Combinations of electrical
impulses on these wires alter the magnetic states of the cores. A line
of cores, some magnetized and some neutral, represents a number or other
collection of symbols in much the same way as a combination of dots
and dashes stands for a word in Morse code. Up to 32,768 of these 'words'
can be stored in the 704's high-speed magnetic core memory. Additional
"words" can be held in auxiliary storage by attaching magnetic drum
See all available vintage
Radio News articles.
Tracking the Man-Made Satellite
By Max Gunther
A complex and elaborate "recording" system" will be used to keep
track of the tiny sphere after it is launched in space.
time during the International Geophysical Year that begins July 1, 1957,
there will culminate one of the most ambitious experiments - and certainly
the best-publicized - in all scientific history. From the Patrick Air
Force Missile Test Center on Cape Canaveral, Florida, a tiny, man-made
moon will be launched. It will be carried by rocket to a height of 200
to 300 miles, then pushed horizontally to a speed of 17,000 to 18,000
miles an hour. If all goes well, it will then settle itself in an elliptical
orbit around the earth, there to stay for several weeks, or perhaps
a year, or perhaps even longer. Science will have taken its first major
step into outer space.
Nobody has ever tried anything like this before; hundreds of uncontrollable
variables make the outcome of the experiment impossible to predict.
One of the largest imponderables is the path that the satellite will
take. At this stage of the moon-making art, it is impossible to control
or foretell the exact speed of the satellite, its height above the earth's
surface, the inclination of its orbit to the equator, or the orbit's
shape. Thus, the tiny globe, measuring less than two feet in diameter,
could easily become lost to view in the sky like a toy boat misplaced
in the Atlantic Ocean.
To forestall any such comi-tragic ending to the experiment, scientists
plan to make wide use of electronic tracking and computing equipment.
At the heart of all satellite-watching operations will be the fastest
large-scale digital computer manufactured by International Business
Machines Corporation - the "704" Electronic Data Processing Machine.
The 704 computer installation will be housed in Washington, D. C., in
a large building already beginning to fill up with equipment. This equipment
will include not only a central data-processing or calculation unit,
but also a platoon of subsidiary units to handle such functions as printing,
reading, recording, and conversion from one form of data-input (such
as punch cards) to another (for example, magnetic tape). This high-powered
installation will be served by its own power supply. It will also have
its own air-conditioning system to carry off the heat it generates in
Over-all view of the IBM 704 Electronic Data Processing Machine
which will calculate and predict the course of the earth satellite
at tremendous speeds. This installation has been made at the
"Project Vanguard" Computing Center in Washington. D. C. Radio
signals emitted by the satellite will be relayed to this Center,
where machine will process the information and compute sphere's
Dr. John P. Hagen, director of "Project Vanguard," is shown here
with a full-scale cutaway model of the earth satellite designed by scientists
working under his direction at the Naval Research Laboratory in Washington.
D.C. The instrumentation shown inside includes telemetering equipment
which will transmit a radio signal to earth after satellite has been
sent into space. Information is then relayed to computer.
Heading the staff of the computer installation will be Dr. Paul Herget,
noted astronomer who is director of the Cincinnati Observatory and a
consultant to the Naval Research Laboratory. Dr. Herget is familiar
with IBM equipment, having used the 704 computer's forerunner, the 701,
in a widely applauded planet-tracking operation two years ago. By carefully
computing the orbit of a minor planet named "Athalia," which had been
discovered by astronomers and subsequently lost again, Dr. Herget and
the 701 pointed to the precise spot in the sky where "Athalia" ought
to be. It was.
To understand how the Vanguard Computing Center will operate, it
is useful to know exactly where it fits into the satellite program as
a whole. Like numerous other International Geophysical Year (IGY) programs,
the satellite experiment is designed for the specific purpose of expanding
scientific knowledge of the earth. Scholars and scientists in many fields
will observe the satellite, gleaning information from it on such subjects
as solar radiation, cosmic rays, meteors, the earth's gravitational
field and atmosphere. The actual launching of the moon, a task dubbed
"Project Vanguard" because it must precede all other parts of the satellite
program, will be carried out by the U. S. Army, Navy, and Air Force,
under general Navy management. The launching has been made a military
responsibility simply because the military services have had more practice
than anyone else in building and firing rockets.
Three rocket stages with a length of 72 feet and a maximum diameter
of 45 inches are expected to put the man-made moon in its orbit. The
first stage, a Viking-like rocket carrying several tons of liquid fuel,
will push the satellite up to a height of 35 to 40 miles. The second
stage, also a liquid-fueled rocket and probably - like the first stage
- controlled from the ground, will blast upward to 130 or 140 miles,
reaching a speed of more than 10,000 miles an hour. After the second-stage
fuel burns out, the momentum of the assembly is expected to carry it
somewhere between 200 and 300 miles above the earth. The second-stage
rocket hull will be jettisoned, and the third stage will begin to fire.
Now an extremely critical set of maneuvers will take place. They
will not be controllable from the ground, but will depend entirely on
pre-set automatic devices. These devices are counted on to direct the
final rocket on a course roughly parallel with the earth's surface,
and to hold it on that course until it reaches a speed as near as possible
to the desired 17,000-plus miles per hour.
Finally, the satellite will be ejected from the rocket to travel space
on its own. Like the natural moon, it will be held in its orbit by a
compromise of centrifugal force and the earth's gravity. The shape of
the orbit will be determined by the direction and speed at which it
leaves the last rocket. Too great a deviation from the desired speed
and direction will result in the satellite's (1) cutting down into the
top layers of atmosphere, where friction will cause it to disintegrate
in white heat like a meteor; or (2) establishing an orbit that carries
it so far away from the earth as to make effective observation extremely
difficult or virtually impossible.
Dr. Paul Herget at the console of the IBM 704 Electronic Data
Processing Machine. He heads the "Project Vanguard" Computing
Center in Washington where this system is being used to predict
and calculate the orbit of the man-made earth satellite.
If all goes as planned, the artificial moon will settle into an orbit
somewhere between these extremes. It will travel in the same general
direction as the earth's rotation, most probably at an inclination of
30 to 45 degrees to the equator. Thus, it will be seen to rise in the
west and set in the east. It is expected to circle the earth roughly
once everyone and one-half hours. Scientists assume that, unlike the
natural moon, it will meet just enough resistance from air and other
particles to slow it down gradually, until finally it drops into denser
atmosphere and burns up.
Since the satellite's orbit cannot be predicted prior to the launching,
there is no way in which observers can be told now where to look for
it in the sky. The tiny moon may be visible for brief periods under
certain conditions at dawn and dusk, when it reflects the sun's rays
at just the right angle, but this cannot be counted on as a foolproof
way to keep track of the satellite. Some means must be provided to keep
it under continuous observation. This is where the electronic computer
center comes in.
Inside the satellite will be, among other instruments and devices,
a miniature radio transmitter from which will emanate a continuous signal.
This signaling system is named "Minitrack," in reference to the midget
size of the equipment. Its signal will be picked up by a series of ground
Minitrack stations located roughly in a north-south line extending from
the mid-latitude region of the U. S. to the latitude of Chile in South
America. Each station will take several readings as the satellite passes
overhead; the readings will each consist of a precise placement of the
satellite in the sky as measured from the station, together with an
exact time of measurement.
These readings will be relayed from the Minitrack stations to a communications
center in Washington, D. C. From here, the readings will go by direct
teletype to the Vanguard Computing Center.
Immediately upon receipt at the Computing Center, the Minitrack measurements
will be translated into punched-card form. The cards will then, in most
cases, be fed directly into the 704 computer for a complex series of
calculations. Cards can be used effectively when there is a relatively
small amount of input data, as in the case of the satellite measurements,
to be subjected to a large amount of manipulation in the computer. If
the input data were greater - as in the case of business accounting
records, for example - the punched-card data would be transferred to
magnetic tape, which can be "read" electronically at vastly higher speeds
than can cards.
Taking the Minitrack sightings as points along the satellite's orbit,
the computer will, in effect, connect the points with a line and thus
calculate the full orbit. It will continually recalculate the orbit
throughout the life of the satellite. As the midget moon completes more
and more revolutions, and as ever more measurements are made, the computer's
accuracy will steadily increase. Before long, the calculated orbit will
even include perturbations, or "wiggles," caused by variations in the
earth's gravitational field, attraction of the natural moon and other
heavenly bodies, and other factors-perhaps including some not now foreseen.
The magnetic core storage unit of the IBM 700 series computer.
This is the "memory" of the machine. Many frames of magnetic
core arrays. consisting of tiny cores strung on copper wires.
provide high-speed storage unit.
The computer will have other jobs to do besides marking out the satellite's
true orbit. One of the most complex tasks will be that of calculating
the man-made moon's shadow path on the earth's surface, or, to put it
more accurately, the path traced on the surface by an imaginary vertical
line drawn from ground to satellite. The computer will be able to predict
this shadow path in advance. Then, by carrying its calculations still
further, it will be able to work out a useful - in fact, indispensable
- timetable for the benefit of official visual tracking stations and
individual scientific observers participating in IGY. The computer will
tell each of these observation posts exactly where and when to aim its
telescope so that the satellite passes through the field of vision.
Without this precise timetable, telescopic observers would have small
hope of catching the tiny moon. It will traverse the sky at a rate of
one degree, or roughly two diameters of the natural moon, per second.
These calculations are not easy. While the satellite is in its orbit,
it will be independent of the earth's rotation beneath it. Each time
the little moon completes a circle, the earth will have rotated 1400
to 1600 equatorial miles to the east. Thus, if the satellite is launched
at an angle of 40 degrees to the equator, its shadow path after twenty
or thirty revolutions will be a curved line that weaves back and forth
between 40 degrees north latitude and 40 degrees south, crisscrossing
itself many times.
If a precise telescope-aiming timetable were worked out by human
computers with paper and pencil, they could never keep pace with the
fast-moving satellite - much less get ahead of it and predict its course.
It will take an electronic computer, capable of such feats as multiplying
or dividing approximately 4700 ten-digit numbers per second, to keep
up with the required pace.
In making its calculations, the computer will rely principally on
a highspeed magnetic core storage, or "memory." This storage will contain
the computer's instructions, now being worked out and programmed in
the computer by Vanguard and IBM experts. When the various tracking-station
data are submitted to the computer, it will act on the data in accordance
with its memorized instructions.
Essentially, the computer's storage function works by means of doughnut-shaped
cores, about the size of pinheads, which are strung on a complex of
wires in such a way that several wires pass through each core. Combinations
of electrical impulses on these wires alter the magnetic states of the
cores. A line of cores, some magnetized and some neutral, represents
a number or other collection of symbols in much the same way as a combination
of dots and dashes stands for a word in Morse code.
Up to 32,768 of these "words" can be stored in the 704's high-speed
magnetic core memory. Additional "words" can be held in auxiliary storage
by attaching magnetic drum units. The 704 can also control ten magnetic
tape units with a capacity of 900,000 "words" each.
The results of the Vanguard 704's computations will flow from the
machine in three principal forms. Some of the information will come
out in printed form, by means of a direct printer attached to the 704.
Some will be on magnetic tape, for printing later on a tape-to-print
device. Still other information will be presented in visual form on
an ingenious device known as the Cathode-Ray Tube Output Recorder. This
device will picture the computer's calculations graphically. It will
show, for example, the actual shape of the satellite's orbit as plotted
by the 704. It will also show the shape of the shadow path, or any other
aspect of the satellite's travels that can usefully be displayed in
The IBM 740 cathode-ray tube output recorder (CRT), a visual
display unit which pictures the output of the 704 Electronic
Data Processing machine in the form of engineering symbols,
words, numbers, or geometrical figures. The orbit of the earth
satellite can be plotted on the screen of the tube as the information
is being computed by the machine. With this unit, "Project Vanguard"
scientists will trace the course of the satellite over the face
of the earth below the orbit of the device.
This recorder actually incorporates two cathode-ray tubes. One, a
21-inch tube, is used for immediate display of information worked out
in the computer. The other, a seven-inch tube, is designed to work with
a 35-mm. camera for recording purposes. This recording device will be
used to advantage in the satellite program. Photographs of the midget
moon's shadow path, together with marked-off arrival times, will be
superimposed on maps of regions having favorable observing conditions.
In the U. S., people living in the southern half of the country will
have the best chance of seeing the satellite. The angle of inclination
at which it will be launched has not yet been announced, but a general
assumption is that the angle will neighbor 40 degrees. The 40th parallel
runs through Philadelphia in the east and about 150 miles north of San
Francisco in the west; thus, moon-watching conditions will be most probably
favorable east, west, or south of these cities.
Visual observation of the satellite will become increasingly important
as time goes on. Some weeks after the artificial moon is launched, if
it stays in orbit that long, the batteries powering its Minitrack transmitter
will die. From then on, all measurements will have to be made optically,
or by other means that require no help from the satellite itself. Long
before this time, however, the computer will have reached a fine enough
degree of accuracy in its orbit calculations so that the tiny sphere,
though no longer calling out its own position, will never be lost in
the sky as long as it continues to revolve.
Where will be the profit in this program, aside from the sheer excitement
of it? The profit, scientists hope, will lie in a flood of new and useful
knowledge that can be had from this and other satellites almost certain
to be launched in years to come. Many observation posts, not directly
connected with Project Vanguard, will be watching the satellite as it
speeds around the planet. The Smithsonian Institution, for example,
plans a large-scale moon-watching operation, as do numerous universities
and other scholarly and scientific bodies throughout the world. Most
of them will be aided by the Vanguard Computing Center.
The satellite's orbit itself will offer much information to observers.
The earth is not a perfect sphere; nor is its mass uniform throughout.
The perturbations of the satellite's orbit, subjected to various calculations,
will add to present knowledge of these irregularities. Another area
of inquiry is the nature of space at the 200-mile-and-up level. It is
supposed to contain tiny meteoric particles that fall in a continual
rain toward the earth, as well as highly rarified air. The drag effects
of these substances will be measurable in the satellite's orbit, thus
offering a clue to their density.
Inside the satellite will be about ten pounds of instruments (total
weight of the sphere: a little over 20 pounds). These instruments will
gather data about the sun's radiation, cosmic rays, and other phenomena
that scientists have not been able to assess accurately because the
earth's atmosphere interferes. Sensitive receiving equipment on the
ground will pick up the data recorded by the space-travelling instruments.
Though the first man-made satellite has not yet left the ground,
scholars and scientists are already speculating delightedly about future
moons. As the science of rocketry progresses, it is altogether likely
that fuels will be developed to provide more thrust per pound. At present,
it takes a colossal tonnage of propellant to hoist a 20-pound sphere
into an orbit; the satellite itself is only a minute fraction of the
vehicle's total weight. As new fuels are developed, it may be possible
to launch larger satellites, capable of carrying more instruments and
gathering more data for science. Whatever is done in the field in years
ahead, however, there is almost certain to be an electronic computer
handling a key phase of the program.
Posted March 24, 2014