July 1965 Electronics World
Table of Contents
Wax nostalgic about and learn from the history of early electronics. See articles
Electronics World, published May 1959
- December 1971. All copyrights hereby acknowledged.
Space exploitation and exploration
has always advanced quickly.
Sputnik and Explorer were launched in 1957 and 1958, respectively. They were
the world's first artificial satellites, and had only one-way communications from
onboard scientific payloads to earth stations which picked up the signals (many
amateur radio operators received the data as well). In a little over half a
decade, multiple two-way communications satellites were in orbit, and instrumented
probes had already reached the moon, Venus, and Mars. Results of the
International Geophysical Year (IGY) effort are rightfully credited with setting
everything in motion. This article from a 1965 issue of Popular Electronics
magazine reports on the state of the art in satellite technology. Not mentioned
is the concurrent rapid advances being made in rockets, tracking stations, and orbital
and space navigation capabilities which were an integral part of the program.
Experiments in Space
The Ranger moon probe which recently photographed the moon surface.
By Joseph H. Wukek, Jr.
New knowledge, new processes and techniques, new materials, and new designs have
all come out of our scientific program for the exploration of space. Article describes
sounding rockets, scientific satellites, and deep-space probes.
Editor's Note: The following article is the first ill a group of stories that
will cover details on our scientific experiments in space. This article covers the
subject from a general point of view. Subsequent stories will go into far more detail
on each of the many experiments that are now being conducted. Such items as the
purpose of the various experiments, how each one operates, the special transducers
used, and how the information is transmitted back to earth will be included.
With the technological advances in rocketry during the past twenty years, new
regions for exploration were opened to Man. No longer would scientists and engineers
be satisfied to study only the phenomena of our earth and its atmosphere, or view
that small fraction of the universe visible through telescopes. With rockets probing
several hundred miles above the earth, more information could be gathered about
our globe and its surroundings than was heretofore possible.
In 1957 the USSR launched the first artificial earth satellite. Since that time,
payload capabilities of launch vehicles have steadily increased, so that now we
find a variety of instrumented package in space. We are no longer limited to several
hundred miles altitude, or to an earth orbit. The United States has successfully
launched space probes to the Moon and Venus (Rangers 7, 8, 9, and Mariner 2, respectively)
and at the time this was written another Mariner probe (Mariner 4) is enroute to
Mars, some 35 million miles away. (Mariner will, in fact, cover over 100 million
miles enroute to Mars, but the intercept with the distant planet will be made at
the 35-million-mile distance.)
Why Space Experiments?
In any undertaking as expensive as the U.S. space program, and it is expensive,
a citizen might reasonably ask, "Why?" The classic answer of Sir Edmund Hillary,
who, when asked why he led an expedition in scaling Mount Everest, replied, "Because
it was there," is probably an unsatisfactory answer to many critics of the program.
They argue with some justification that these funds might be better spent on cancer
research, or education, or a host of other worthwhile pursuits. Beyond improving
our prestige as a nation of technological "doers," the space program has had other
benefits. Communications and weather-predicting satellites benefit most of the earth's
inhabitants. In pushing the "state of the art" to new levels, a kind of "technological
fall-out" has taken place.
New knowledge gained in the space program has found applications elsewhere. New
processes and techniques, new materials, and new designs have been spawned by work
in the aerospace industry. Much of the impetus given to the development of integrated
circuits has come from the space program. These circuits will make possible small,
low-powered, reliable, and inexpensive electronic equipment. The field of medical
electronics benefits by the research in medical instrumentation. The proposed U.
S. Supersonic Transport (SST) will rely heavily on knowledge gained in the space
program. In addition to the important new knowledge gained, American industry and
commerce stand to gain from these efforts, and thus the citizen will ultimately
Artist's concept of OGO with its 220 lbs. of scientific instruments
which are used to investigate aurora and radiation.
Tiros is designed to photograph meteorological conditions.
If we limit our discussion to unmanned space vehicles and only those vehicles
which have been launched to date, three categories are suggested: 1. sounding rockets,
2. satellites, and 3. deep-space probes.
Sounding Rockets. Sounding rockets are vehicles designed to pass through the
region of up to several hundred miles above the earth. These rockets are usually
smaller vehicles, up to 50 feet in length. The lifetime of these probes is on the
order of several minutes. Information is relayed via telemetry (TM) channels, and/or
a recovery of the instrument package may be effected by parachute and floatation
bag if the re-entry is over water. These experiments are relatively inexpensive
since older, obsolescent rockets may be used, and the ground support requirements
are minimal. The launch vehicle may be one or several stages of rocket, with the
experiment mounted in a detachable nose cone.
Satellites are vehicles which are designed to orbit a planet and, in particular,
the Earth. Schemes for orbiting other planets have been described, but we limit
our discussion to earth satellites.
The Orbiting Geophysical Observatories (OGO) are an example of the new generation
of satellites. The eccentric-orbiting version (EGO), will be launched by the two-stage
Atlas-Agena B to an orbit of 68,000 miles maximum (apogee), to 175 miles minimum
(perigee). The polar-orbiting version of the satellite (POGO) will have apogee and
perigee of about 570 and 150 miles, respectively. POGO will be launched by Thor-Agena.
At this writing, one EGO satellite is in orbit.
Many other earth satellites have been launched or are in the development stage.
Some of these are for scientific measurements. Others, such as the Syncom, Telstar,
and Echo are primarily communications satellites. So-called active satellites contain
receiver/transmitter equipment to receive, amplify, and re-transmit high-frequency
r.f. over the horizon. Passive satellites such as Echo, merely act as reflectors
for r.f. transmission.
Yet another class of satellites is the Tiros (Television Infrared Observation
Satellite) type, used to gather data for weather prediction.
This class of vehicle ordinarily contains equipment similar to that of sounding
rockets and earth satellites, but has a mission in deep-space. The Mariner 2 vehicle
which passed Venus in mid-December 1962 was of this category, as were the Ranger
Experiments in Space
While a wide variety of approaches to instrumentation exists for each particular
experiment, most experiments may be classified as one of six general types: 1. micrometeoroid
measurements, 2. magnetic measurements, 3. solar-plasma measurements, 4. radiation
measurements, 5. wave-propagation measurements, and 6. astronomical observations.
Micrometeoroid Measurements. The far reaches of space abound in cosmic debris.
We are familiar with meteors and meteorites, which are seen burning in the earth's
atmosphere or occasionally find their way to a collision with the earth's surface.
These particles may be seen either by optical means or radar.
General types of experiments performed by the EGO satellite.
The Mariner satellite, which is now on its way to the planet
But many smaller parts, too small to be seen by radar, exist above the earth's
atmosphere. Particles of less than 1 millimeter diameter (a bout 4/100th of an inch)
are called micro-meteoroids. These particles may be traveling at speeds of up to
100,000 feet per second (more than 68,000 miles per hour), and hence could prove
hazardous to a manned space vehicle. This cosmic dust, moving at high velocities,
has a "sandblasting" effect on materials. Solar batteries used for power aboard
satellites may have their efficiency impaired by the eroding effect of the "sandblast."
By measuring the size, velocity, and abundance of these particles, scientists and
engineers hope to be able to determine the level of hazard these particles represent.
The recently orbited Pegasus satellite is being used to take such measurements.
Magnetic Measurements. Of itself, the earth's magnetic field is of interest.
A detailed measurement and mapping of the earth's field will aid in understanding
related phenomena. Trapped radiation, the aurora, radio propagation through space,
and magnetic storms are believed related in some measure to the magnetic field of
The presence and strength, or absence, of magnetic fields in the vicinity of
a planet or our moon give some indication of that body's composition. Hence we find
that magnetic field measurements are of interest in virtually every satellite or
Solar Plasma. Solar plasma, or solar winds, are tremendous hydrogen clouds which
emanate from the Sun. These clouds move at several hundred miles per second and
contain α particles (helium ions with + 2 electron charge), protons, and electrons
as well as hydro-gen. Measurements to date indicate that the solar plasma is always
present but is subject to broad fluctuations in composition and energy. Moreover,
the times of increased solar activity, as with solar flares, have a marked effect
on the plasma. Radio communication is greatly affected during solar flares, and
extraterrestrial radio noise increases.
The origin and mechanism of solar plasma is not well understood at this time.
It is hoped that further experimentation will assist in a better understanding of
the nature of this phenomenon.
Radiation Measurements. With the discovery by Van Allen of the radiation belts
which bear his name, much interest was aroused in space radiation measurements.
In addition to these natural belts of radiation, U.S. and Soviet high-altitude nuclear
explosions have added charged particles to these regions, altering the Van Allen
belts' composition and shape. While the Van Allen belts are believed to be primarily
high-speed electrons and protons, more measurements are needed to better chart these
regions. Clearly, these radiation regions could prove hazardous to space travelers.
In addition to electron/proton radiation, other radiations are found in space.
Gamma rays (γ rays, similar to high-energy x-rays ), cosmic rays, and particles
emitted from the sun are also of interest. Also, since our atmosphere filters much
of the radiation from the sun, measurements of solar radiation made above the atmosphere
will yield more information about the sun. With such an abundance and mixture of
particles and waves, more experimental work is in order.
Since we rely heavily upon the properties of the ionosphere for much of our radio
communication, it behooves us to seek a better understanding of this region.
The radio propagation properties of the ionosphere are subject to variation from
day to evening, and with the seasons. Solar activity, particularly the eleven-year
sunspot cycle, produces severe changes in the ionosphere.
In addition to radio propagation measurements, noise measurements are also of
Since the earth's atmosphere greatly reduces the resolving power of terrestrial
telescopes, we find it desirable to make observations from above this region. Hence
telescopes and/or TV cameras aboard satellites and probes can give improved resolution
to astronomical observations. This fact was dramatically illustrated when the TV
camera aboard Ranger 7 showed the Moon's surface with a resolution of 1 1/2 feet,
some 1000 times better than any earth telescope.
Related to this type of experiment are the meteorological satellites, which look
toward, rather than away from, the earth. By relaying photographs of cloud formations
and earth heat radiation patterns, meteorologists have added information at their
disposal for predicting the weather. The Tiros satellite in 1961 warned of the approach
of hurricane Esther two days before conventional systems detected its buildup.
In addition to the kinds of measurements we have discussed, most space vehicles
carry so-called "housekeeping" instruments. These devices monitor and transmit information
having to do with the spacecraft itself. Temperatures, pressures, power bus voltages,
attitude (orientation of spacecraft), vibration, acceleration, shock, velocity,
time from launch, etc. are of interest during launch and over extended periods of
the vehicle's mission.
Housekeeping data is usually transmitted by the telemetry equipment at a slower
rate than experimental data since usually housekeeping data is changing at a slower
rate. During launch it may be that only housekeeping data is transmitted, and experiments
might not be turned on until the region of interest is reached.
Posted August 30, 2022