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OFFICE OF PUBLIC INFORMATION
JET PROPULSION LABORATORY, CALIFORNIA INSTITUTE OF TECHNOLOGY
NATIONAL AERONAUTICS AND SPACE ADMINISTRATION
PASADENA, CALIFORNIA. TELEPHONE 354-5011
FOR RELEASE: A.M.'s of THURSDAY, DECEMBER 14, 1972
The era of planetary exploration began 10 years ago
today with the arrival at Venus of a 447-pound automatic
scientific spacecraft -- Mariner 2.
At 19:59:28 hours (GMT) on December 14, 1962, Mariner 2
crossed the orbit of Venus at an altitude of 34,854 kilometers
(21,645 miles) above the surface.
It was just a few seconds before 3 P.M. at NASA
Headquarters in Washington, D.C., and noon at the Jet Propulsion
Laboratory in Pasadena, California, where engineers manned the
Mariner operations center.
During the 109-day Earth to venus interplanetary
crossing, Mariner 2 had monitored the environment of that unknown
region of space and relayed to Earth a constant stream of data
gathered by its instruments.
-- A faint interplanetary magnetic field persists along
the ecliptic plane.
-- A constant "solar wind" flows from the sun at
velocities ranging from 320 to 770 kilometers per
second (200 to 480 miles per second).
-- The incidence of cosmic dust, or micrometeoroids, is
less near Venus than near Earth.
-2-
-- Intensity of cosmic rays, energetic particles
originating outside our solar system, is nearly
constant.
Then, on December 14, Mariner 2 and its science payload
was 1000 times closer to Venus than Earth instruments had ever
been. For 35 minutes surrounding the closest approach of the
spacecraft, two radiometers scanned the planet -- on its night
side, day side and along the day-night terminator.
-- Venus is blanketed by cold, dense clouds in the
upper atmosphere.
-- Its surface temperature averages 800?o\ Fahrenheit.
Lead and zinc would melt on the surface.
-- The temperatures are essentially the same on the
dark and sunlighted sides of the planet.
-- A cold spot was found in the cloud tops.
Other instruments showed that Venus has neither a
measurable magnetic field nor radiation belts, both of which
characterize Earth's physical environment.
Dr. William H. Pickering, director of the Jet
Propulsion Laboratory, which designed, built and conducted the
missions of the Mariner series of spacecraft, commented 10 years
ago:
"While Mariner 2 is the first interplanetary spacecraft
flying by other planets, then orbiting the planets, and finally
landing instruments on their surfaces. Exploring the solar
-3-
system, becoming acquainted with the planets, answering questions
about extraterrestrial life -- these are the challenges that lie
ahead.
During the decade which began with the historic flight
to Venus, five more Mariners have capitalized on the Mariner 2
technology, new planets have been selected for study and the
Soviet Union has mounted a successful planetary exploration
program following a number of early failures.
-- Mariner 4 flew by Mars in July of 1965 at an
altitude of 6118 miles, obtaining man's first
close-up pictures of the planet. The 21 photos
revealed Mars is heavily cratered.
-- Mariner 5 and the Russian Venera 4, in October,
1967, together with ground-based radar measurements,
determined that the Venus atmosphere is 75 to 100
times more dense than Earth's.
-- Mariners 6 and 7 reached Mars in July and August,
1969, taking 200 pictures of the surface from as
close as 2200 miles.
-- And last October 27 ended an 11 1/2-month Mars
orbiting mission by Mariner 9 which has revised all
previous concepts of the planet. Mariner 9 gathered
science data during 698 revolutions of Mars,
provided a map of the entire planet and showed
evidence of volcanic activity and free-flowing water
in Mars' geologic history.
-4-
Next year the United States will attempt the first
two-planet mission with a single spacecraft. Mariner 10 will
skim by Venus using the planet's gravity to be propelled on to
Mercury, closest planet to the sun.
Two advanced Mariner-class spacecraft will be launched
in 1977 to explore Jupiter and Saturn. Again, using the gravity-
assist technique, both Mariners will fly past Jupiter in 1979 and
Saturn in 1981.
And, as also predicted 10 years ago, a soft landing on
Mars is scheduled for 1976 by the Viking spacecraft, which will
attempt to answer questions concerning extraterrestrial life.
12/8/72
#640
trial life.
12/8/72