[Illustration: Mariner spacecraft]
MARINER
_MISSION TO VENUS_
Prepared for the National Aeronautics and Space Administration BY THE
STAFF, Jet Propulsion Laboratory, California Institute of Technology
COMPILED BY HAROLD J. WHEELOCK FOREWORD BY W. H. PICKERING, Director,
Jet Propulsion Laboratory, California Institute of Technology
McGRAW-HILL BOOK COMPANY, INC.
New York, San Francisco, Toronto, London
MARINER MISSION TO VENUS
Copyright © 1963 by the Jet Propulsion Laboratory, California Institute
of Technology. All Rights Reserved. Printed in the United States of
America.
Library of Congress Catalog Card Number 63-17489.
This book describes one phase of the U. S. civilian space program—the
journey of the Mariner spacecraft to the vicinity of Venus and beyond.
It reports upon the measurements taken during the “flyby” on December
14, 1962, when Mariner reached a point 21,598 miles from the planet, and
36,000,000 miles from Earth (communication with the spacecraft was
continued up to a distance of approximately 54,000,000 miles from
Earth). The Mariner mission was a project of the National Aeronautics
and Space Administration, carried out under Contract No. NAS 7-100 by
the Jet Propulsion Laboratory, California Institute of Technology.
FOREWORD
For many centuries scientific information about the planets and the vast
void that separates them has been collected by astronomers observing
from the surface of the Earth. Now, with the flight of Mariner II, we
suddenly have in our hands some 90 million bits of experimental data
measured in the region between Earth and the planet Venus. Thus, man for
the first time has succeeded in sending his instruments far into the
depths of space, and indeed, in placing them near another planet. A
whole new area of experimental astronomy has been opened up.
This book is a brief record of the Mariner Project to date and is
designed to explain in general terms the preliminary conclusions.
Actually, it will be months or years before all of the data from Mariner
II have been completely analyzed. The most important data were the
measurements made in the vicinity of the planet Venus, but it should
also be noted that many weeks of interplanetary environmental
measurements have given us new insight into some of the basic physical
phenomena of the solar system. The trajectory data have provided new,
more accurate measurements of the solar system. The engineering
measurements of the performance of the spacecraft will be of inestimable
value in the design of future spacecraft. Thus, the Mariner II
spacecraft to Venus not only looks at Venus but gives space scientists
and engineers information helpful in a wide variety of space ventures.
A project such as Mariner II is first a vast engineering task. Many
thousands of man-hours are required to design the complex automatic
equipment which must operate perfectly in the harsh environment of
space. Every detail of the system must be studied and analyzed. The
operations required to carry out the mission must be understood and
performed with precision. A successful mission requires every member of
the entire project team to do his task perfectly. Whether it be the
error of a designer, mechanic, mathematician, technician, operator, or
test engineer—a single mistake, or a faulty piece of workmanship, may
cause the failure of the mission. Space projects abound with examples of
the old saying, “For want of a nail, the shoe was lost ...,” and so on,
until the kingdom is lost. Only when every member of the project team is
conscious of his responsibility will space projects consistently
succeed.
The Mariner II Project started with the Lunar and Planetary Projects
Office of the Office of Space Sciences at NASA in Washington. Jet
Propulsion Laboratory, California Institute of Technology, personnel
provided the main body of the team effort. They were heavily supported
by industrial contractors building many of the subassemblies of the
spacecraft, by scientists planning and designing the scientific
experiments, and by the Air Force which supplied the launching rockets.
Several thousand men and women had some direct part in the Mariner
Project. It would be impossible to list all of those who made some
special contribution, but each and every member of the project performed
his job accurately, on time, and to the highest standards.
Mariner II is only a prelude to NASA’s program of unmanned missions to
the planets. Missions to Mars as well as Venus will be carried out.
Spacecraft will not only fly by the planets as did Mariner II, but
capsules will be landed, and spacecraft will be put into orbit about the
planets. The next mission in the Mariner series will be a flyby of the
planet Mars in 1965.
By the end of the decade, where will we be exploring, what will new
Mariners have found? Will there be life on Mars, or on any other planet
of the solar system? What causes the red spot on Jupiter? What is at the
heart of a comet? These and many other questions await answers obtained
by our future spacecraft. Mariner II is just a beginning.
W. H. Pickering
_Director_
Jet Propulsion Laboratory_
California Institute of Technology_
April, 1963_
CONTENTS
_FOREWORD_
_ACKNOWLEDGMENTS_
CHAPTER 1 VENUS
_The Double Star of the Ancient World_
_The Consensus prior to Mariner II_
_The Cytherean Riddle: Living World or Incinerated Planet_
CHAPTER 2 PREPARING FOR SPACE
_A Problem in Celestial Dynamics_
_The Organization_
_NASA: For Science_
_JPL: JATO to Mariner_
_General Dynamics: The Atlas_
_Lockheed: Agena B_
CHAPTER 3 THE SPACECRAFT
_The Spaceframe_
_The Power System_
_CC&S: The Brain and the Stopwatch_
_Telecommunications: Relaying the Data_
_Attitude Control: Balancing in Space_
_Propulsion System_
_Temperature Control_
_The Scientific Instruments_
CHAPTER 4 THE LAUNCH VEHICLE
_The Atlas Booster: Power of Six 707’s_
_The Agena B: Start and Restart_
CHAPTER 5 FLIGHT INTO SPACE
_Mariner I: An Abortive Launch_
_Mariner II: A Roll before Parking_
_The Parking Orbit_
_Orientation and Midcourse Maneuver_
_The Long Cruise_
_Encounter and Beyond_
_The Record of Mariner_
CHAPTER 6 THE TRACKING NETWORK
_Deep Space Instrumentation Facility_
_The Goldstone Complex_
_The Woomera Station_
_The Johannesburg Station_
_Mobile Tracking Station_
CHAPTER 7 THIRTEEN MILLION WORDS
_Communication Control_
_The Operations Center_
_Central Computing Facility_
CHAPTER 8 THE SCIENTIFIC EXPERIMENTS
_Data Conditioning System_
_Cosmic Dust Detector_
_Solar Plasma Experiment_
_High-energy Radiation Experiment_
_The Magnetometer_
_Microwave Radiometer_
_Infrared Radiometer_
_Mariner’s Scientific Objectives_
CHAPTER 9 THE LEGACY OF MARINER
_Space without Dust?_
_The Ubiquitous Solar Wind_
_High-energy Particles: Fatal Dosage?_
_A Magnetic Field?_
_The Surface: How Hot?_
_Cloud Temperatures: The Infrared Readings_
_The Radar Profile: Measurements from Earth_
CHAPTER 10 THE NEW LOOK OF VENUS
_APPENDIX_
_INDEX_
ACKNOWLEDGMENTS
Researching the material, gathering and comparing data, preparation of
review drafts and attending to the hundreds of details required to
produce a document on the results of such a program as the Mariner
mission to Venus is a tremendous task. Special acknowledgment is made to
Mr. Harold J. Wheelock who, on an extremely short time scale, carried
the major portion of this work to completion.
Although the prime sources for the information were the Planetary
Program office and the Technical Divisions of the Jet Propulsion
Laboratory, other organizations were extremely helpful in providing
necessary data, notably the George C. Marshall Space Flight Center, the
Lockheed Missiles and Space Company, the Astronautics Division of the
General Dynamics Corporation, and, of course, the many elements of the
National Aeronautics and Space Administration.
JPL technical information staff members who assisted Mr. Wheelock in
production of the manuscript and its illustrations were Mr. James H.
Wilson, Mr. Arthur D. Beeman and Mr. Albert E. Tyler. JPL is also
grateful to Mr. Chester H. Johnson for his help and suggestions in
preparing the final manuscript.
CHAPTER 1
VENUS
Halfway between Los Angeles and Las Vegas, the California country climbs
southward out of the sunken basin of Death Valley onto the
3500-foot-high floor of the Mojave desert.
On this immense plateau in an area near Goldstone Dry Lake, about 45
miles north of the town of Barstow, a group of 85-foot antennas forms
the nucleus of the United States’ world-wide, deep-space tracking
network.
Here, on the morning of December 14, 1962, several men were gathered in
the control building beneath one of the antennas, listening intently to
the static coming from a loudspeaker. They were surrounded by the exotic
equipment of the space age. Through the window loomed the gleaming metal
framework of an antenna.
Suddenly a voice boomed from the loudspeaker: “The numbers are changing.
We’re getting data!”
The men broke into a cheer, followed by an expectant silence.
Again the voice came from the speaker: “The spacecraft’s crossing the
terminator ... it’s still scanning.”
At that moment, some 36 million miles from the Earth, the National
Aeronautics and Space Administration’s Mariner[1] spacecraft was passing
within 21,600 miles of the planet Venus and was radioing back
information to the Goldstone Station—the first scientific data ever
received by man from the near-vicinity of another planet.
At the same time, in Washington, D.C., a press conference was in
progress. Mr. James E. Webb, Administrator of the National Aeronautics
and Space Administration, and Dr. William H. Pickering, Director of the
Jet Propulsion Laboratory, stood before a bank of microphones. In a few
moments, Dr. Pickering said, the audience would hear the sound of
Mariner II as it transmitted its findings back to the Earth.
Then, a musical warble, the voice of Mariner II, resounded in the hall
and in millions of radios and television sets around the nation.
Alluding to the Greek belief that harmonious sounds accompanied the
movement of the planets, Dr. Pickering remarked that this, in truth, was
the music of the spheres.
Mariner II had been launched from Cape Canaveral, Florida, on August 27,
1962. Its arrival at Venus was the culmination of a 109-day journey
through the strange environment of interplanetary space. The project had
gone from the drawing board to the launching pad in less than 11 months.
Mariner had taxed the resources and the manpower of the Jet Propulsion
Laboratory, California Institute of Technology; the Atlantic Missile
Range centering at Cape Canaveral; theoretical and experimental
laboratories at several universities and NASA centers; numerous elements
of the aerospace industry; and, of course, NASA management itself.
To the considerable body of engineers scattered around the world from
Pasadena to Goldstone to South Africa to Australia, the warble of
Mariner was something more than “the music of the spheres.” Intercept
with Venus was the climax of 109 days of hope and anxiety.
To the world at large, this warbling tone was a signal that the United
States had moved ahead—reached out to the planets. Mariner was exploring
the future, seeking answers to some of the unsolved questions about the
solar system.
THE DOUBLE STAR OF THE ANCIENT WORLD
Venus, the glittering beacon of our solar system, has intrigued man for
at least 4,000 years. The Babylonians first mentioned the brilliant
planet on clay tablets as early as 2,000 years before Christ. The
Egyptians, the Greeks, and the Chinese had thought of Venus as two stars
because it was visible first in the morning and then in the evening sky.
The Greeks had called the morning star Phosphorus and the evening star
Hesperos. By 500 B.C. Pythagoras, the Greek philosopher, had realized
that the two were identical.
Galileo discovered the phases of Venus in 1610. Because of the planet’s
high reflectivity, Copernicus falsely concluded that Venus was either
self-luminous or else transparent to the rays of the Sun.
Venus was tracked across the face of the Sun in 1761, from which event
the presence of an atmosphere about the planet was deduced because of
the fuzzy edges of the image visible in the telescope. Throughout the
eighteenth and nineteenth centuries, Venus continued to excite growing
scientific curiosity in Europe and America.
[Illustration: _Venus’ orbit is almost circular. At inferior
conjunction, the planet is between the Earth and the Sun,
approximately 26,000,000 miles away; at superior conjunction, Venus
is on the other side of the Sun. The elongations are the farthest
points to the east and the west of the Earth._]
Even the development of giant telescopes and the refinement of
spectroscopic and radar astronomy techniques in recent times had yielded
few indisputable facts about Venus. Until radar studies, made from
Goldstone, California, in 1962, neither the rate nor the angle of axial
spin could be determined with any degree of accuracy. The ever-shifting
atmosphere continued to shield the Venusian surface from visual
observation on Earth, and the nature of its atmosphere became an
especially controversial mystery.
THE CONSENSUS PRIOR TO MARINER II
Venus is a virtual twin of the Earth; it approaches our planet closer
than any celestial body except the Moon, a few vagrant comets, and other
such galactic wanderers. Long fabled in song and legend as the most
beautiful object in the sky, Venus has an albedo, or reflectivity
factor, of 59% (the Moon has one of 7%). In its brightest or crescent
phase, Venus glows like a torch, even casting a distinct shadow—the only
body other than the Sun and the Moon yielding such light.
Venus’ diameter is approximately 7,700 miles, compared with Earth’s
7,900. Also as compared with 1.0 for the Earth, Venus’ mean density is
0.91, the mass 0.81, and the volume 0.92.
The Cytherean orbit (the adjective comes from Cytherea, one of the
ancient Greek names for Aphrodite—or in Roman times, Venus—the goddess
of love) is almost a perfect circle, with an eccentricity (or
out-of-roundness) of only 0.0068, lowest of all the planets. Venus rides
this orbital path at a mean distance from the Sun of 67.2 million miles
(Earth is 93 million miles), and at a mean orbital speed of 78,300 miles
per hour, as compared with Earth’s 66,600 miles per hour.
It also has a shorter sidereal period (revolution around the Sun or
year): 224 Earth days, 16 hours, 48 minutes. Estimates of the Venus
rotational period, or the length of the Venus day, have ranged from
approximately 23 Earth hours to just over 224 Earth days. The latter
rotation rate would be almost equivalent to the Venusian year and, in
such case, the planet would always have the same face to the Sun.
Venus approaches within 26 million miles of the Earth at inferior
conjunction, and is as far away as 160 million miles at superior
conjunction, when it is on the opposite side of the Sun.
The escape velocity (that velocity required to free an object from the
gravitational pull of a planet) on Venus is 6.3 miles per second,
compared with Earth’s escape velocity of 7 miles per second. The gravity
of the Earth is sufficient to trap an oxygen-bearing atmosphere near the
terrestrial surface. Because the escape velocity of Venus is about the
same as that of Earth, men have long believed (or hoped) that the
Cytherean world might hold a similar atmosphere and thus be favorable to
the existence of living organisms as we know them on the Earth. From
this speculation, numerous theories have evolved.
THE CYTHEREAN RIDDLE: LIVING WORLD OR INCINERATED PLANET
Before Mariner II, Venus probably caused more controversy than any other
planet in our solar system except Mars. Observers have visualized Venus
as anything from a steaming abode of Mesozoic-like creatures such as
were found on the Earth millions of years ago, to a dead, noxious, and
sunless world constantly ravaged by winds of incredible force.
Conjectures about the Venusian atmosphere have been inescapably tied to
theories about the Venusian topography. Because the clouds forming the
Venusian atmosphere, as viewed from the Earth through the strongest
telescopes, are almost featureless, this relationship between atmosphere
and topography has posed many problems.
Impermanent light spots and certain dusky areas were believed by some
observers to be associated with Venusian oceans. One scientist believed
he identified a mountain peak which he calculated as rising more than 27
miles above the general level of the planet.
Another feature of the Venusian topography is the lack of (detectable)
polar flattening. The Earth does have such a flattening at the poles and
it was reasoned that, because Venus did not, its rate of rotation must
be much slower than that of the Earth, perhaps as little as only once
during a Venusian year, thus keeping one face perpetually toward the
Sun.
Another school of thought speculated that Venus was covered entirely by
vast oceans; other observers concluded that these great bodies of water
have long since evaporated and that the winds, through the Cytherean
ages, have scooped up the remaining chloride salts and blasted them into
the Venusian skies, thus forming the clouds.
Related to the topographic speculations were equally tenuous theories
about its atmosphere. It was reasoned that if the oceans of Venus still
exist, then the Venusian clouds may be composed of water droplets; if
Venus were covered by water, it was suggested that it might be inhabited
by Venusian equivalents of Earth’s Cambrian period of 500 million years
ago, and the same steamy atmosphere could be a possibility.
Other theories respecting the nature of the Venusian atmosphere,
depending on how their authors viewed the Venusian terrain, included
clouds of hydrocarbons (perhaps droplets of oil), or vapors of
formaldehyde and water. Finally, the seemingly high temperature of the
planet’s surface, as measured by Earth-bound instruments, was credited
by some to the false indications that could be given by a Cytherean
ionosphere heavily charged with free electrons.
[Illustration: _As seen from Earth, Venus is brightest at its
crescent phases as shown in these six photographs made by the
100-inch telescope at Mt. Wilson, California._]
However, the consensus of pre-Mariner scientific thinking seemed
generally to indicate no detectable free oxygen in the atmosphere; this
fact inveighed against the probability of surface vegetation, because
Earth-bound vegetation, at least, uses carbon dioxide and gives off
oxygen into the atmosphere. On the other hand, a preponderance of carbon
dioxide in the Venusian atmosphere was measured which would create a
greenhouse effect. The heat of the Sun would be trapped near the surface
of the planet, raising the temperature to as high as 615 degrees F. If
the topography were in truth relatively flat and the rate of rotation
slow, the heating effect might produce winds of 400 miles per hour or
more, and sand and dust storms beyond Earthly experience. And so the
controversy continued.
But at 1:53.13.9 a.m., EST, on August 27, 1962, the theories of the past
few centuries were being challenged. At that moment, the night along the
east Florida coast was shattered by the roar of rocket engines and the
flash of incandescent exhaust streams. The United States was launching
Mariner II, the first spacecraft that would successfully penetrate
interplanetary space and probe some of the age-old mysteries of our
neighbor planet.