In March 1979 Voyager 1 swept past Jupiter, photographing both the giant
planet and five of its moons. Four months later, a companion spacecraft,
Voyager 2, made a similar encounter. Now, with Jupiter receding behind
them, both spacecraft are headed toward the outer reaches of our solar
system. In November 1980, Voyager 1 will fly past Saturn. Voyager 2,
traveling at slower speeds, will reach the same way station in August
1981. Beyond there, the itinerary is less certain. In January 1986,
eight years after its departure from Earth, Voyager 2 may sail within
range of Uranus, taking closeup pictures of that distant planet for the
first time. Long after they have exhausted their fuel supplies and their
radios have fallen silent, both spacecraft will continue their traverse
through space and beyond our solar system, on an endless journey.
[Illustration: _An Apollo 12 astronaut retrieves Surveyor 3 hardware
for Earth laboratory analysis after 30 months exposure on lunar
surface._]
[Illustration: _Viking Lander 2 surveys the boulder-strewn Utopian
Plain and reddish sky of Mars._]
Preliminary results of the Voyager encounters with Jupiter are presented
in this booklet. As you examine the pictures, you will be participating
in a revolutionary journey of exploration. Living in a society where
many accomplishments and products are billed as “extraordinary,”
“stupendous,” “once in a lifetime,” or “unique,” we sometimes lose our
perspective. Conditioned to hyperbole, we fail to recognize those
advances that are truly exceptional. We need a historian’s vantage point
to identify the events that can literally change the course of
civilization. So it is that every student of history recognizes the
importance of the Renaissance, an extraordinary time when man looked
outward, reaching beyond the traditions of the past to study his place
in the natural world. The results were apparent in art, architecture,
and literature, in new philosophic and governmental systems, and in the
staggering scientific revolution exemplified by Galileo’s first
examination of the heavens with a telescope, and in his stubborn support
of the heretical assertion that the Earth was _not_ the center of the
solar system.
Historians writing a hundred or two hundred years from now may well look
on the latter part of the twentieth century as another turning point in
civilization. For the first time, we explored beyond Earth—first the
Moon, then the neighboring planets, and finally the outermost planets,
the very fringe of our solar system.
How will the historian evaluate this period of exploration? First,
perhaps, he will describe the Apollo program as a visionary example of
great cooperative ventures that can be accomplished by many individuals,
private companies, and government institutions. He will describe the
subsequent space ventures that weave a fabric of cooperation and
goodwill between nations.
He will point out the technological advances incorporated in unmanned
spacecraft, sophisticated robots able to control their own activities
and solve their own problems. He will mention the revolution in
microelectronics—the art of fabricating complex electrical control
circuits so small the eye cannot perceive them, a revolution accelerated
by the requirement to conserve weight and generate performance in
interplanetary spacecraft. He will point to the introduction of new
products, particularly in areas of communication, medical treatment, and
energy conversion.
[Illustration: _Galileo orbiter and probe mission to Jupiter in 1985
will expand upon the Voyager investigations of the Jovian system._]
[Illustration: _A solar electric propulsion spacecraft would eject
an instrumented probe toward Halley’s comet in 1986 and continue on
to rendezvous with another comet, Tempel 2._]
Turning his attention to the environment, the historian will almost
surely suggest that the first widespread realization of the fragile
natural balances on Earth came at a time when we were first able to see
our Earth in its entirety. The impact of a picture of Earth from deep
space, a luminously blue globe surrounded by darkness, has probably been
more persuasive than lengthy treatises describing the complex ways in
which our system of rocks, plants, animals, water, and air is
interrelated. On a more practical level, the historian will point to the
new understanding of our terrestrial environment. The composition and
structure of other planetary atmospheres—on Venus, Mars, and
Jupiter—provide important clues to what may happen in our own
atmosphere, especially if we disrupt the chemical composition. Study of
the primitive crusts of the Moon, Mars, and Mercury permits us to
reconstruct the first billion years of Earth history, a time when
chemical elements were being concentrated in activity ultimately leading
to the formation of important ore deposits. Unmanned spacecraft missions
to the Sun increase our understanding of that most fundamental of all
energy sources, paving the way for the efficient conversion of solar
energy into many practical applications, and releasing us from
dependence on ever-decreasing reserves of fossil fuels. Spacecraft
circling the Earth study the upper atmospheric processes that play major
roles in controlling our weather. These same spacecraft look down on
Earth, aiding us with increasingly accurate forecasts of weather and
crop productivity.
Looking beyond matters of technology and the environment, the historian
may cite the latter part of the twentieth century as a time of explosive
exploration, comparable to the 15th and 16th century exploration of the
Earth’s oceans and the distant lands that bounded them. In a sense,
exploration—whether it is physical or intellectual—provides its own
rewards. The United States has always been a nation that moves forward,
pushing back the frontiers of the West, pushing back the frontiers of
social and economic development, and now pushing back the frontiers of
space. It is arguable that this spirit of exploration is indispensable
to a vigorous society, and that any society that ceases to explore, to
inquire, and to strive is only a few years from decline.
And so the historian may recall the early days of lunar exploration, the
Apollo project, the landing of unmanned Viking spacecraft on Mars, and
the encounters of Voyager spacecraft with Jupiter and Saturn as the
first steps in a sustained program of space exploration—a program that
is profoundly changing man’s perspective of himself, of the Earth, and
of the larger cosmos beyond.
Thomas A. Mutch, _Associate Administrator for Space Science_
_National Aeronautics and Space Administration_