The International Geophysical Year (IGY) began on July 1
of 1957 and ran through December 31 of 1958 (actually IGYaaH
- IG year-and-a-half). It was the dawn of space / high altitude
flight and there was a great need to learn as much as possible
about the physics of the upper atmosphere and the void of space.
The USSR successfully flew their first three
Sputnik satellites and the U.S. was scrambling to get
Echo into orbit (finally on August 12, 1960, after
the end of IGY). The Cold War was at its peak (Bay
of Pigs incident was just a few years away), and the science
world was looking for a way to provide a unifying tie between
the planet's countries. "During this time, more than 5,000 scientists
and engineers of more than 60 nations are conducting intensive
investigation and study of the earth, the atmosphere and the
sun. Into these 18 months are crammed 30 or 40 ordinary years
of research as science attempts to get a better picture of our
geophysical environment," per author Jordan McQuay.
James Van Allen, one of the IGY's progenitors, discovered
the eponymous radiation belt encompassing the Earth during that
Electronics and the IGY
Part I: Electronics contributes to the success of the International
By Jordan McQuay
One of the most significant scientific undertakings in the
history of mankind is the IGY or International Geophysical Year.
It began last July and continues until next December - a period
of 18 months.
Fig. 1 - This typical IGY observing station
(Fritz Peak, Colorado) houses a photoelectric photometer and
other optical equipment.
During this time, more than 5,000 scientists and engineers
of more than 60 nations are conducting intensive investigation
and study of the earth, the atmosphere and the sun. Into these
18 months are crammed 30 or 40 ordinary years of research as
science attempts to get a better picture of our geophysical
At more than 1,000 field stations, scientists and engineers
are exploring every major land and sea area. They are studying
the earth's core and crust, and the atmosphere around our globe.
And throughout these many and diversified studies and explorations,
electronics plays an important role.
For only the science of electronics can detect, observe and
measure many of the phenomena associated with the earth and
the sun as they move through space. So great is this role of
electronics that much of the success of the IGY depends directly
on its use.
The IGY program covers a dozen major areas of scientific
activity. These include meteorology, aurora and airglow, geomagnetism,
cosmic rays, glaciology, gravity, longitude and latitude determinations,
oceanography, seismology, solar activity, and rocket and satellite
studies of the upper atmosphere. Although the earth-satellite
program is perhaps the most popularized, this is only one of
the areas of scientific activity during the IGY.
Fig. 2 - A rawin set - a radiosonde and directional
radio receivers - used to collect meteorological data
In most of these areas, electronics is utilized in some way
to detect, collect, measure and record data concerning the earth
and its atmosphere. Through electronics, these data provide
not only new basic knowledge but also applications in many fields
of human interest - from transpolar air travel to better radio
communications, air navigation and weather predictions.
This, in essence, is the purpose of the IGY. And electronics
is an important means of making many of these investigations
With every advance of civilization, knowledge of the weather
has grown more and more necessary. To cope with change in the
weather, reliable predictions - particularly long-range predictions
- are needed.
One difficulty in predicting weather has been the lack of
adequate data from the Arctic and Antarctic regions, which influence
the world's weather.
During the IGY two drifting and several fixed ground stations
in the Arctic and more than 50 ground stations in the Antarctic
have been established to collect data influencing the weather.
For the first time in history, adequate meteorological coverage
of the Southern Hemisphere is being provided.
Fig. 3 - An Aerobee-Hi rocket a few moments
after launching. US Army Photographs
At these various ice-bound sites, balloon-borne weather instruments
are sent aloft and radio back information on air pressure, temperature,
humidity, precipitation and prevailing winds. Radiosonde and
rawinsonde equipment provide this data at heights up to about
100,000 feet. At each site, information is collected and then
transmitted-via radio circuits - to central points for analysis
In addition to the Arctic and Antarctic stations, there are
more than a hundred other weather-observing stations in more
temperate regions, particularly in the Western Hemisphere (Fig.
Stations are not identically equipped. A variety of electronic
and other measuring instruments is used at many sites.
Observations of solar radiation are made with pyrheliometers
and recorders. Infrared measurements are made with infrared
absorption-cell hygrometers. Sky brightness and sunshine duration
are recorded with photometric switches. Atmospheric ozone is
measured with Dobson spectrophotometers. Other ground-based
devices detect and measure radiated sun heat, snowfall, wind
and temperature. At selected sites throughout the world, the
sun is photographed every 30 seconds.
Radiosondes at Work
Important to the study of meteorology at the various IGY
sites is a continuous knowledge of wind direction and velocity,
air temperature and humidity and other data from lower regions
of the upper atmosphere.
Instruments for recording these data are known as radiosondes
and are carried aloft by balloons about 6 or 7 feet in diameter.
Data collected by a radiosonde are broadcast to ground-based
radio receivers for further analysis. Each radiosonde weighs
about 2 pounds and is about the size of a hand telephone. Besides
being a compact radio transmitter, it carries a thermometer,
a hygrometer for measuring air humidity, a barometer and a miniature
battery for a power source.
After release, the balloon rises while the miniature transmitter
flashes vital statistics to ground-based receiving stations.
Each receiver automatically tracks the radiosonde and records
the drift of the balloon as well as data transmitted by the
radiosonde as it moves through space.
A combination of a radiosonde and several ground-based receivers
is known as a rawin (Fig. 2) or rawinsonde. The system operates
up to altitudes of about 100,000 feet, when the balloon bursts.
The radiosonde is then eased down by parachute to forestall
possible injury to persons or damage to property. Most balloons
and airborne gear are lost. But they have fulfilled their mission
in meteorology for the IGY.
Data collected by the rawin are sent by radio or wire lines
to central control points, where they are recorded and analyzed
further - usually by electronic data-processing machines. Data
are stored on tapes or punched on cards and ultimately used
for regional weather predictions.
Although these data - collected at altitudes up to 100,000
feet - are important, for long-range weather prediction there
is a need for similar data collected from much higher altitudes.
Collection of such data is possible only by use of special rockets.
The Upper Atmosphere
Meteorological and other data are being collected from the
upper atmosphere by four kinds of rockets:
The Aerobee-Hi is a liquid-fuel rocket. In a 6-cubic-foot
space, it carries a payload of 150 pounds of scientific equipment
to an altitude of about 170 miles. It is 23 feet long and about
15 inches in diameter.
The Nike-Cajun uses a solid propellant and carries a 40-pound
payload to an altitude of more than 100 miles.
The Nike-Deacon also uses a solid propellant to carry a 40-pound
payload to an altitude of about 75 miles. Both rockets use the
Nike as a booster.
The Rockoon is a Deacon rocket carried to about 80,000 feet
by a Skyhook balloon before the rocket is actually fired. It
carries a 40-pound payload to an altitude of more than 60 miles.
Of the dozen or so rockets fired to date, most were the Aerobee-Hi
type. The majority of them were fired in the Arctic region.
See Fig. 3.
Particularly important in meteorology is the measurement
of upper-air temperatures and the collection of air samples
to determine their composition. This can be done with rockets,
which also provide a way of determining wind speed and direction
at heights never before possible.
Temperature increases with increasing altitude because the
ozone absorbs ultra-violet radiation. Thus, great out-bursts
of ultra-violet radiation caused by a solar flare may result
in temperature increases which are reflected at the earth's
surface in marked weather changes. With these data, collected
by the rocket and relayed to ground stations, much more accurate
weather forecasting is possible.
Two methods of measuring temperatures at high altitudes with
rockets have been used successfully during the IGY. One system
is based on the principle that the speed of sound is influenced
by temperature. The speed of sound is measured through a series
of small detonations that occur just outside the rocket housing
at closely timed intervals during flight. Microphones on the
ground detect each burst, and the exact time of arrival is recorded
by electronic data-processing equipment. At the same time, radar
and optical tracking equipment determine the exact location
of each detonation in space as the rocket ascends. The position
and time of arrival of each of the successive detonations indicate
the speed of sound through the layer bounded by each burst.
Thus, the mean temperature for each stratum of atmosphere can
be determined electronically.
Another method of temperature measurement requires knowledge
of the angle made by the shock waves off the nose of the rocket
during flight. These waves are detected by pressure-sensitive
probes mounted on the outside of the rocket housing and, after
amplification, are recorded on a magnetic tape inside the rocket.
The data are also telemetered to a receiving station on the
ground. From a knowledge of the fixed angle of the probes plus
the location and speed of the rocket (determined by ground-based
radar), the air temperature along the upward path of the rocket
can be determined electronically.
Fig. 4 - Miniature radar-beacon transceiver
(right) and its power supply for rockets used to explore the
upper atmosphere. US Army Photographs
Air is sampled at high altitudes by sending special vacuum
bottles aloft within a rocket. At predetermined altitudes, the
containers are opened, and then closed and sealed by electromechanical
devices. Rockets are also equipped with instruments to detect
and record other phenomena under study during the IGY.
Preliminary results during the IGY indicate that up to about
40 miles altitude, atmospheric gasses are completely mixed.
Above that level, the amount of argon (a heavy gas) decreases
and the amount of helium (a light gas) increases.
Rockets in flight are located and tracked by ground-based
radar stations and sound-ranging stations. Each rocket carries
a small transponder beacon (Fig. 4) which transmits a return
signal to IGY stations on the ground.
Radar tracking also provides a measure of safety. If the
rocket veers off course during its powered ascent, such a deviation
is noted quickly by the ground-based radar equipment. If the
behavior of the rocket becomes dangerously erratic, a change
of signal is transmitted from the ground to the radio receiver
in the rocket. This, in turn, breaks the fuel line and terminates
To protect the delicate electronic instruments in the rocket
from landing shock, they are carefully packed and braced. Some
rockets are constructed so the nose and tail assemblies are
blown apart during downward flight. A nylon parachute brings
down the nose section that houses the electronic measuring and
Most rockets carry out several different IGY experiments
during a single flight. Thus the total number of flights is
not indicative of the true importance of this phase of the IGY
The several ground stations used to track and control the
rocket are connected via communications circuits using conventional
radio or wire facilities. Collected data are evaluated and stored
at central locations by electronic processing and storing equipment.
Investigation of the upper atmosphere by radiosondes and
rockets is supplemented by other IGY studies, all intended to
enhance our knowledge of this region that surrounds us.
The atmosphere - extending above 100,000 feet and thinning
out into nothingness hundreds of miles above the earth - plays
a dominant role in our lives. It provides a shield against lethal
radiation from the sun and from dangerous cosmic radiation.
It maintains the heat balance of the earth, so surface temperatures
are suitable for life. And it affects our lives in many other
Under study during the IGY are events and conditions that
take place more than 50 miles above the earth's surface. The
sun dominates most of these events, which include aurora, airglow,
cosmic rays, geomagnetism and other solar activities.
Any unusual solar radiation - either in intensity or kind
- influences the upper atmosphere. This, in turn, affects radio
communication, navigational systems and other electronic activities
dependent to some degree on the transmission and reception of
electromagnetic waves through space.
Solar activity is generally measured in terms of an 11-year
sunspot cycle. Sunspot bursts or other active phenomena on the
surface of the sun have lifetimes varying from a few days to
a few months, invariably according to the 11-year time scale.
Brief spurts of activity occur in some solar regions and may
last from a few minutes to a few days.
Variations in any of these solar activities frequently determine
weather conditions on earth. For this reason, the IGY program
was purposely timed to coincide with the peak of sunspot activity
so that geophysical events in the upper atmosphere would be
at their maximum.
To observe these solar phenomena, a network of more than
400 ground-based stations has been established around the world.
The stations are spaced to allow a continuous optical and electronic
watch of the surface of the sun and the upper atmosphere. Events
occurring in the visible as well as radio frequencies are measured
and recorded. These include the number and size of sunspots,
solar flares and solar (radio-frequency) noise - all correlated
with time. At these and additional stations in the Arctic and
Antarctic, aurora and airglow are also observed and recorded.
Aurora or dancing light is the visible evidence of the bombardment
of the earth's atmosphere by charged particles from the sun.
It is a luminous trace, usually occurring near the north and
south geomagnetic poles of the earth.
Airglow is a faint glow of light, somewhat like aurora, caused
by a chemical reaction in the upper atmosphere of Arctic and
Antarctic regions. Both aurora and airglow interfere with radio
At IGY stations in polar regions, aurora and airglow are
observed and recorded with radiosonde equipment associated with
photoelectric photometers, scanning spectrometers and high-dispersion
Photographs of aurora and airglow are taken at regular intervals
with specially built automatic-sequence all-sky cameras - which
cover the sky from horizon to horizon. Each instrument incorporates
a 16-mm motion-picture camera which photographs the entire sky
as seen in a convex mirror. Exposures are taken about once every
Data on auroral forms and intensities are classified and
recorded electronically in terms of sky location and time, reduced
to punched-card form and filed for future reference. This work
is done by conventional electronic data-processing machines.
During periods of marked solar activity, rockets are also
used to obtain data for study and record. In airglow experiments,
photon counters are encased in the rocket. These counters are
used at various wavelengths in the visible spectrum with their
output coupled to amplifiers containing photo-multiplier tubes
and filters. Auroral articles - almost infinitesimal dust -
are collected and measured with Geiger counters, proportional
and scintillation counters, ionization chambers and related
equipment mounted within the rocket. All data collected by rockets
are recorded and then telemetered to ground-based receiving
When scientists cannot observe an aurora visually or photographically,
the course of the aurora is followed with radar equipment. The
path of an aurora can also be studied by means of radio and
radio astronomy. The pattern of auroral interference with ordinary
radio transmissions on the earth and with the arrival on earth
of radio-frequency emissions from the sun and other planets
provides valuable data for predicting radio propagation.
Cosmic rays are other solar phenomena. Although their origin
is a mystery, their presence can be detected and their characteristics
examined. These are essentially positively charged particles
that bombard the earth from all directions. Excessive bursts
of cosmic rays frequently coincide with other ionospheric disturbances
and are so severe that they not only interfere with but sometimes
prevent radio communication.
At the many IGY observation stations around the world, cosmic
rays are studied with other solar activities. Used for this
purpose are cloud chambers, ionization chambers, window Geiger
counters, electronic impulse counters and other special instruments
to detect and measure cosmic rays. Information is recorded in
terms of time for later comparison with other solar disturbances
Raw data are exchanged between IGY stations via radio communication
- usually using high-speed teletype-writers. At key central
stations, data from all observing points are correlated and
recorded by electronic data-processing equipment.
A region of rarefied ionized gases - from 50 to 250 miles
above the earth - is known as the ionosphere. It is electrically
active because of ultra-violet radiation from the sun, and reflects
radio waves from earth much as a mirror reflects light. For
this reason, radio communication is entirely dependent on the
ionosphere for long-distance transmission.
The region is far from stable. It is composed of layers of
ionization which change radically with time of day, with season,
and even from year to year. Its radio-wave reflecting characteristics
also vary with prominent solar activities. A flare on the sun
is frequently followed by an ionospheric disturbance that blacks
out all long-distance radio communication. Active sunspots and
violent auroral displays also affect the ionosphere and result
in major paralyses of long-distance communication.
Fig. 5 - Antenna array of an IGY observing
station (Boulder, Colo.) used to study effects of the ionosphere
on radio-wave propagation.
National Bureau of Standards
Through detailed study of the ionosphere and its many and
varied characteristics, some of th e mysteries of this ionized
region may be deduced during the IGY. Observing stations are
endeavoring to collect data on the characteristics of all layers
or part of the ionosphere. Of particular significance are data
on variations of charge density with altitude.
Layers are measured vertically and obliquely from each observing
station at regular intervals, using automatic multifrequency
ionospheric recorders. This equipment normally sweeps from 1
through 25 mc in a period of about 20 seconds, and this sweep
is repeated about every 20 minutes. Radar data are recorded
on 35-mm film, which is processed and scaled daily for significant
Rockets are also used to determine ionospheric charge densities
in three ways: In the first, the delay time of an electromagnetic
pulse sent from the ground station to the rocket is measured.
In the second, two harmonically related signals are transmitted
from the rocket in the ionosphere; with a known phase shift,
the index of refraction in the vicinity of the rocket shell
is a measure of the charge density. In the third, the charge
density is determined from the effect of the ionosphere on DOVAP
(Doppler, velocity and position) signals. Data are either recorded
by electronic equipment within the rocket or raw information
is telemetered to ground-based receiving equipment where it
is recorded and analyzed.
Nearly a hundred observing stations have been established
at points around the world specifically for the purpose of measuring
the position and density of layers of the ionosphere. Much of
this work, particularly in the. Antarctic, has never before
Data of this type from all ionospheric and other observing
stations are collected and assembled to obtain a worldwide pattern
for prediction purposes. See Fig. 5.
Other investigation of the ionoshere include the use of solar
spectrographs, encased in rockets, to determine the distribution
of ozone in the upper atmosphere. A radio-frequency mass spectrometer
is used to measure the chemical and ion composition of the ionosphere.
These plus wind and other measurement are either recorded electronically
within the rocket or are transmitted to the ground observing
stations for study and record.
Another field of intensive study is the recording and measurement
of atmospheric radio noises. At principal stations of the global
IGY network, noise is recorded continuously, 24 hours a day,
on magnetic tape, with appropriate time references for comparison
with other meteorological data.
Low-frequency or whistling atmospheric noise is the subject
of a special study during the IGY in an effort to identify the
origin and define the characteristics of this kind of radio
Other IGY studies relating to the ionosphere include investigation
of oblique-incidence forward scatter, sweep-frequency back scatter,
absorption and other phenomena relating to the propagation of
Any unusual solar or ionospheric activity in one region of
the world is communicated to other IGY stations by a global
radio network. This allows more intense study of the same phenomenon
and its effects at various sites throughout the world.
Next month - a look at the earth satellite and its place
in the International-Geophysical Year.
To Be Continued...
February 1958 Radio-Electronics
Wax nostalgic about and learn from the history of early electronics. See articles
published 1929 - 1948. All copyrights hereby acknowledged.
Posted February 27, 2014