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Space Digest                Fri, 12 Feb 93       Volume 16 : Issue 152

Today's Topics:
    Electronic Journal of the ASA (EJASA) - February 1993 [Part 1]

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Date: 7 Feb 93 20:52:00 GMT
From: Larry Klaes <[e-mail]>
Subject: Electronic Journal of the ASA (EJASA) - February 1993 [Part 1]
Newsgroups: sci.astro,sci.space,sci.misc,alt.sci.planetary,soc.culture.soviet

                          THE ELECTRONIC JOURNAL OF
                  THE ASTRONOMICAL SOCIETY OF THE ATLANTIC

                      Volume 4, Number 7 - February 1993

                         ###########################

                              TABLE OF CONTENTS

                         ###########################

          * ASA Membership and Article Submission Information

          * The Soviets and Venus, Part 1 - Larry Klaes

                         ###########################

                         ASA MEMBERSHIP INFORMATION

        The Electronic Journal of the Astronomical Society of the Atlantic
    (EJASA) is published monthly by the Astronomical Society of the
    Atlantic, Incorporated.  The ASA is a non-profit organization dedicated
    to the advancement of amateur and professional astronomy and space
    exploration, as well as the social and educational needs of its members.

        ASA membership application is open to all with an interest in
    astronomy and space exploration.  Members receive the Journal of the
    ASA (hardcopy sent through United States Mail - Not a duplicate of this
    Electronic Journal) and the Astronomical League's REFLECTOR magazine.
    Members may also purchase discount subscriptions to ASTRONOMY and
    SKY & TELESCOPE magazines.

        For information on membership, you may contact the Society at any
    of the following addresses:

        Astronomical Society of the Atlantic (ASA)
        c/o Center for High Angular Resolution Astronomy (CHARA)
        Georgia State University (GSU)
        Atlanta, Georgia  30303
        U.S.A.

        [e-mail]

        ASA BBS: [phone], 300/1200/2400 Baud.

        or telephone the Society Recording at [phone] to leave your
    address and/or receive the latest Society news.

        ASA Officers and Council -

        President - Eric Greene
        Vice President - Jeff Elledge
        Secretary - Ingrid Siegert-Tanghe
        Treasurer - Mike Burkhead
        Directors - Becky Long, Tano Scigliano, Bob Vickers
        Council - Bill Bagnuolo, Michele Bagnuolo, Don Barry, Bill Black,
                  Mike Burkhead, Jeff Elledge, Frank Guyton, Larry Klaes,
                  Ken Poshedly, Jim Rouse, Tano Scigliano, John Stauter,
                  Wess Stuckey, Harry Taylor, Gary Thompson, Cindy Weaver,
                  Bob Vickers


                             ARTICLE SUBMISSIONS

        Article submissions to the EJASA on astronomy and space exploration
    are most welcome.  Please send your on-line articles in ASCII format to
    Larry Klaes, EJASA Editor, at the following net addresses or the above
    Society addresses:

        [e-mail]
        or - ...!decwrl!verga.enet.dec.com!klaes
        or - [e-mail]
        or - [e-mail]

        You may also use the above addresses for EJASA back issue requests,
    letters to the editor, and ASA membership information.

        When sending your article submissions, please be certain to include
    either a network or regular mail address where you can be reached, a
    telephone number, and a brief biographical sketch.

        Back issues of the EJASA are also available from the ASA anonymous
    FTP site at chara.gsu.edu (131.96.5.29)

                                DISCLAIMER

        Submissions are welcome for consideration.  Articles submitted,
    unless otherwise stated, become the property of the Astronomical
    Society of the Atlantic, Incorporated.  Though the articles will not
    be used for profit, they are subject to editing, abridgment, and other
    changes.  Copying or reprinting of the EJASA, in part or in whole, is
    encouraged, provided clear attribution is made to the Astronomical
    Society of the Atlantic, the Electronic Journal, and the author(s).
    Opinions expressed in the EJASA are those of the authors' and not
    necessarily those of the ASA.  This Journal is Copyright (c) 1993
    by the Astronomical Society of the Atlantic, Incorporated.


                             THE SOVIETS AND VENUS
                                     PART 1

                       Copyright (c) 1993 by Larry Klaes

    The author gives permission to any group or individual wishing
    to distribute this article, so long as proper credit is given,
        the author is notified, and the article is reproduced in its
        entirety.

        Revolving around a small yellow star between the celestial paths
    of a crater-scarred world called Mercury and our blue-white Earth lies
    the planet known as Venus.  Named by the Romans after their goddess of
    beauty and love for its white brilliance in Earth's night sky, Venus
    resembles our planet in both size and mass.  However, while Venus can
    come closer to Earth than any other planet in our solar system, the
    second world from the Sun remained one of the more mysterious places
    in the Universe before the advent of the Space Age.

        The relative brightness of Venus is due to the reflection of Sun-

    light off the planet's enveloping blanket of thick, yellowish clouds.
    Venus' strange atmosphere was discovered by the Russian scientist
    Mikhail Vasilievich Lomonosov during a rare transit of the planet
    across the solar disk in 1761.  For two centuries after Lomonosov's
    revelation, Earth-bound astronomers would find themselves unable to
    penetrate this dominating feature with their optical telescopes to
    learn what lay beneath.

        Wild speculation about Venus arose from the absence of facts to
    explain the state of this alien world.  Through the first half of the
    Twentieth Century, Venus was populated with everything from primeval
    swamps crawling with reptilian creatures to boiling oceans of seltzer
    and oil.  Even such 'basic' planetary information as Venus' rate of
    rotation was unknown because of the continual cloud cover.  Estimates
    on the length of a Venerean day ranged from twenty-four hours to one
    Venerean year, 224.7 Earth days.

        Scientists realized that direct measurements were needed to
    uncover the realities of this moonless world.  Rockets and spacecraft
    capable of reaching other planets were required for the task.

        Competition for the Cosmos

        The early years of the Space Age were dominated by two global
    superpowers, the United States of America and the Soviet Union.
    Shocked into reality on October 4, 1957 with the launch of the Soviet
    satellite SPUTNIK 1, these rival nations boldly pushed their ambitions
    and technologies into the interplanetary realm as part of what was
    termed the Cold War.

        By the dawn of the 1960s, the Soviets had taken a considerable
    lead in this endeavor:  Three of their unmanned space probes had
    already reached Earth's moon, Luna, completing their programmed
    missions.  Other Soviet vehicles, designed to explore the two planets
    nearest Earth - Venus and Mars - were rapidly being prepared for
    their destinations.

        In the Western Hemisphere, the United States had yet to achieve
    a single fully successful lunar mission with their series of PIONEER
    probes.  As a form of consolation, PIONEER 5, a scaled-back Venus flyby
    project, was launched from Cape Canaveral in Florida on March 11, 1960
    to investigate the interplanetary medium between the orbits of Earth
    and Venus.  The information from such an expedition was considered
    vital for the planning of spacecraft which would follow PIONEER's
    charting course all the way to Venus.

        PIONEER 5 became an amazing success:  The solar-powered sphere
    communicated with Earth until June 26, 36.4 million kilometers (22.5
    million miles) from home, a record for that time.  The probe confirmed
    the existence of interplanetary magnetic fields and relayed the sur-
    prisingly strong effects of various solar forces on the spacecraft.
    PIONEER bolstered the confidence of both the National Aeronautics and
    Space Administration (NASA) and the U.S. that they could compete with
    the Soviets in the exploration of deep space.  PIONEER 5 now silently
    circles the Sun once every 312 days.

        Soviet Aims for the Goddess of Love

        On the fourth day of the second month in the year 1961, a rocket
    of the MOLNIYA class roared from a launch pad at the Tyuratam Space
    Center - more widely known as the Baikonur Cosmodrome - in a remote
    region of the Soviet Republic of Kazakhstan.  Atop this powerful coni-
    cal booster was a spacecraft designated by its builders as TYAZHELIY
    SPUTNIK 4, meaning Heavy Fellow Traveler in Russian.  In the West,
    this craft was called SPUTNIK 7.

        News of this launch had been kept from most of the world until
    the mission was well underway.  Nearly all Soviet space missions of
    that era were made government secrets until successful, so that a
    failure would not be able to disgrace the Soviet Union's appearance
    in space.  Even when a mission did work as planned, it was often that
    scant information was released about the craft and its purpose.  The
    ensuing Cold War caused both sides to become paranoid about revealing
    their technological limits to the other.

        Soviet officials claimed that this new SPUTNIK was only a test
    of their latest Automatic Interplanetary Station (AIS) for launching
    spacecraft into higher Earth orbits.  Western experts believed it to
    be the Soviet Union's first attempt to send an unmanned probe to the
    planet Venus, as this was a prime launch "window" for delivering a
    spacecraft to that world.  Whatever the truth, the vehicle never left
    its parking orbit.  The launch platform and alleged Venus probe even-
    tually disintegrated on February 26 upon entering Earth's atmosphere.

        Just one week after the launching of SPUTNIK 7, the Soviets placed
    yet another Heavy Fellow Traveler, TYAZHELIY SPUTNIK 5 (SPUTNIK 8),
    into Earth orbit on February 12.  Within one day of its insertion into
    space, a small vehicle emerged from the orbital platform and was sent
    on its way to the second planet from the Sun.  The West's belief that
    the Soviets were ushering in the era of robotic planetary exploration
    was thus confirmed.

        Renamed VENERA 1 ("Venera" is the Russian word for Venus), the
    first Venus probe acknowledged by the Soviets was a domed, instrument-
    packed cylinder flanked by two solar panels and a radio antenna shaped
    like an open umbrella.  The entire vehicle weighed 643.5 kilograms
    (1,418.9 pounds).  The primary mission plan for this new breed of
    spacecraft was stated as a flyby examination of Venus in late May of
    1961 at a distance of one hundred thousand kilometers (sixty-two
    thousand miles).  During its flight to the target planet, VENERA 1
    would send back data collected on interplanetary gas, dust, magnetic
    fields, and cosmic rays every five days to its controllers on Earth.

        The mission proceeded well until February 22.  On that day, VENERA
    1 was twenty-three million kilometers (fourteen million miles) from
    Earth and set to relay its next batch of gathered information.  Then,
    unexpectedly, no signals were received at the appointed time.  Attempts
    to pick up the probe's transmissions were made again on March 4 and 5
    with the help of the giant Jodrell Bank radio telescope in Great Britain,
    but without success.  VENERA 1 drifted off into heliocentric (solar)
    orbit, no longer of use to those who lofted it into space.

        Should VENERA ever be recovered from the depths of interplane-
    tary space, those who retrieve the Soviet probe will find inside the
    vehicle a small metal representation of Earth.  Sealed within this
    globe is a commemorative medallion identifying the purpose and
    national origin of the Venus craft.  The placing of such artifacts
    aboard deep space probes was destined to become a tradition with both
    the Soviets and the United States.  They serve as a means of speaking
    to those future explorers who would follow, to let them know who and
    what paved the way into the Universe for humanity.

        Despite the overall performance of these first two attempts to
    reach Venus, the VENERA series would eventually become one of the
    Soviet Union's greatest planetary exploration achievements for the
    next quarter century.  True success, however, would have to wait.

        In the meantime, the Soviets were content to finish out 1961 with
    two major victories in one of the most visible areas of their space
    program.  On April 12, cosmonaut Yuri Gagarin became the first human
    to orbit Earth aboard VOSTOK 1.  Nearly four months later, on August 6,
    VOSTOK 2 played host to Gherman Titov, the first cosmonaut to spend an
    entire day in space.  By comparison, the United States had sent two
    astronauts on separate fifteen-minute suborbital flights inside the
    cramped confines of the MERCURY space vehicle in May and July.  The
    U.S. was hard-pressed once again to impress the world with even more
    spectacular space missions.

        Failures and Triumph

        Following the Soviet VENERA missions of early 1961, the next
    occurrence of a rocket launch window to Venus began in the summer of
    1962.  These windows are created when Earth and a particular planet
    are at certain locations in their orbits around the Sun so that the
    least amount of booster energy can be used to launch the most feasibly
    massive spacecraft.  Such an alignment for Venus and Earth occurs
    every nineteen months.

        The United States made the first grasp for Venus in 1962 with
    their unmanned MARINER 1 spacecraft.  Sent skyward from Cape Canaveral
    on July 22 aboard an ATLAS-AGENA B rocket, the flight at first appeared
    to be going well.  Then, a rocket guidance programming error suddenly
    caused the booster to deviate from its planned course.  With the ATLAS-
    AGENA heading towards the shipping lanes of the North Atlantic Ocean,
    the Range Safety Officer (RSO) was forced to destroy the vehicle with
    a radio command to an explosive device aboard the rocket.  A brief rain
    of metal debris showered the water.  The first American spacecraft meant
    for Venus instead met its end in the icy depths of the Atlantic.

        One month later, the Soviets made their first Venus launch attempt
    of the year, but their luck was not much better than America's initial
    try with MARINER 1.  The unnamed vehicle came apart in its Earth
    parking orbit on August 25 and disintegrated upon entering the
    atmosphere three days later.  Two more Soviet Venus probes were
    conducted into space on the first and twelfth days of September, but
    neither craft traveled any further than their brief Earth orbits.
    These failures made it easy to wonder if the two superpowers' current
    technologies were truly up to the task of reaching another planet
    through millions of kilometers of deep space.

        In the midst of these little-known Soviet attempts, the United
    States took their second shot at Venus on the night of August 27.
    MARINER 2, a 203.6-kilogram (448-pound) spacecraft resembling an oil
    rig with two solar panels and a high-gain radio dish antenna, made
    its way into interplanetary space on a risk-filled journey to the
    shrouded world.  Four months later, after a mission punctuated by
    numerous technical and heating problems, MARINER 2 became the first
    spacecraft to successfully reach another planet while still in commu-
    nication with Earth.

        Speeding past the yellow sphere of Venus on December 14 at
    a distance of 34,827 kilometers (21,648 miles), MARINER's two
    radiometers scanned the planet for thirty-five minutes.  From this
    brief examination many important discoveries were made.  One of the
    most startling was that Venus' global surface temperature averaged 427
    degrees Celsius (800 degrees Fahrenheit), hotter than a conventional
    kitchen oven.  Such intense heat was hundreds of degrees above most
    scientists' previous temperature estimations.  It appeared that Venus'
    clouds somehow kept heat from the Sun bottled in, much like a green-
    house allows solar radiation to enter but not to escape.

        The Venerean clouds floated in an unbroken layer fifty-six to
    eighty kilometers (thirty-four to forty-eight miles) thick above the
    planet's baked and arid crust.  The dense atmosphere these clouds
    existed in was thought to exert pressure on Venus' surface twenty to
    thirty times greater than that of Earth's comparatively thin air at
    sea level.

        MARINER 2 also found no evidence for either magnetic fields or
    radiation belts surrounding Venus as they do about Earth.  In less
    than one hour, MARINER's encounter with the second planet from the Sun
    disrupted the decades-old theories of humid swamps and oily oceans,
    along with almost any hope for the existence of Venerean life as
    humans would recognize it.  Venus was more unlike Earth than most
    astronomers had ever dreamed.

        The American spacecraft's findings led not only to a radically new
    view of Earth's nearest planetary neighbor, but also to a rearranging
    of planetary mission priorities for the United States space program.
    NASA decided that the Red Planet, Mars, would be the next goal for
    their unmanned explorers.  The conditions on Venus required more
    extensive study by space vehicles with a technical sophistication
    which was not readily available in the early 1960s.  Mars also
    appeared to be a far more suitable planet for placing manned
    expeditions upon in the foreseeable future.

        The Soviets, meanwhile, pressed on with their missions to Venus.
    For them, the second world appeared to be an easier spacecraft target
    to obtain than Mars:  Every attempt to reach the Red Planet since 1960
    had failed for a variety of mechanical reasons.  Many Soviet astronomers
    were also not entirely convinced of the incredibly harsh environment
    that had been reported about the veiled planet.  Some theorized that
    the high temperature readings by MARINER 2 may have come from the
    planet's ionosphere instead of its surface.  This view kept alive
    the hope that the planet might at least harbor simple organisms.
    Venus still held many secrets to be unlocked.

        The Darkness Before the Dawn

        With all the technical troubles encountered by the Soviets from
    their first Venus and Mars probes, it would have been only logical
    for the program scientists and technicians to conduct further tests
    on their planetary vehicles before sending them to those worlds
    again.  A spacecraft launched from Tyuratam into Earth orbit on
    November 11, 1963, appeared to be the result of such planning.

        COSMOS 21, so named due in part to a 1962 United Nations treaty
    demanding that all spacecraft be given some type of official designa-
    tion, was shuttled into an Earth parking orbit similar to that used by
    other Soviet craft preparing for planetary destinations.  Though no
    launch windows were open for either Venus or Mars at that time, Wes-
    tern experts speculated that COSMOS 21 might have been planned for a
    mission to the vicinity of Venus' solar orbit in a full engineering
    test of spacecraft systems.  If this were the actual scenario, then
    COSMOS 21 must be considered a failure, as no probe left Earth orbit
    and the entire vehicle decayed three days later.

        Whatever the case with COSMOS 21, Soviet scientists apparently
    felt confident enough to launch another series of Venus probes when
    the next window opened in February of 1964.  Unfortunately, this
    confidence did not turn into success that year.  Two rocket launches,
    on February 26 and March 4, apparently failed in mid-flight and their
    payloads were not even given the COSMOS cover nomenclature.  Twenty-
    three days later, a third Venus probe did attain Earth orbit but went
    no further.  COSMOS 27 lasted just one day in space.

        A fourth and final Soviet try at Venus came the following month.
    On April 2, the 'barrier' of Earth orbit, which had stopped all Soviet
    Venus vessels save VENERA 1, was finally breached by ZOND 1, a space-
    craft with a most non-specific cover name.  "Zond" is the Russian word
    for probe.  As with COSMOS, the name was designed to hide the craft's
    true destination, should it end up succumbing like the previous robotic
    explorers and thus bring further embarrassment to its creators.  Though
    little was revealed about ZOND 1, it was probably meant to either
    flyby or impact on Venus in July of 1964, taking measurements of
    interplanetary space in the process.

        The ZOND 1 mission proceeded well until after the last
    communication session on May 14, 1964, when the craft was suddenly
    fallen by the same fate as VENERA 1 three years earlier:  It ceased
    transmitting to Earth.  The Soviets' caution in giving the vehicle a
    generic name appeared to be a wise move for their prestige after all,
    though Western space experts were aware of the spacecraft's basic
    intentions.

        ZOND 1 was the first and last ZOND mission to Venus.  All future
    ZOND probes would be targeted for missions to Luna and Mars.  Soviet
    space scientists now had another nineteen months to make up for the
    Venus project failures of 1964.

        Stranger and Stranger

        By the middle 1960s, new knowledge about Venus was still being
    obtained from the vantage of Earth.  Various radio telescopes around
    the globe had penetrated the planet's thick cloud mask and returned
    to scientists the first radar images of Venus' equatorial regions,
    indicating a number of mountains and plateaus.

        As a bonus from these observations, Venus' true rotation rate was
    finally learned.  The information only served to add to the planet's
    growing reputation for possessing 'bizarre' conditions:  One Venerean
    day (one complete rotation around the planet's axis) equaled 243.1
    Earth days, nineteen days longer than its solar year!  No other known
    world in the solar system rotated so slowly.

        Venus was also discovered to spin on its axis in a retrograde
    fashion (clockwise as seen over the north pole), opposite to most of
    the other planets.  To a person standing on an 'alternate' Venus -
    one with skies free of clouds - the Sun would appear to "rise" in
    the west and "set" on the eastern horizon 116.8 Earth days later.
    Why Venus behaved in this contrary manner remained a mystery.

        So Close, Yet Still So Far

        The year 1965 was a very fruitful one for American lunar and
    planetary efforts.  The last two members of the RANGER series
    successfully completed their brief photographic missions to Luna,
    making way for the SURVEYOR fleet of unmanned lunar landers.  Deeper
    into the solar system, MARINER 4 became the first spacecraft to flyby
    the planet Mars and return to Earth close-up images of its surpri-
    singly barren and cratered surface.

        The Soviets, on the other hand, were not accomplishing the
    showcase space missions they had presented in earlier years.  Their
    numerous attempts to soft land an unmanned vehicle on Earth's moon
    finished either in solar orbit or as wreckage in the lunar dust.
    The lone Soviet Mars mission of that year, ZOND 2, suffered a major
    power drop and ceased communications just four months before its
    planetary encounter in early August.

        On the plus side, the robot vehicle ZOND 3 took several dozen
    images of Luna's hemisphere hidden from Earth in July of 1965, the
    first such pictures since the Soviet LUNA 3 mission six years earlier.
    ZOND 3 then headed out to the orbit of Mars for a series of spacecraft
    system tests in 1966.  There was now only one feasible goal left for
    the Soviet space program to regain some true prestige in the arena of
    planetary exploration:  Venus.

        The first space probe to be given the official VENERA designation
    since 1961, VENERA 2 was successfully launched on its way to Venus
    on November 12, 1965, followed by VENERA 3 four days later.  The two
    probes were the most ambitious Soviet expeditions to the second world
    from the Sun yet created.  VENERA 2 would attempt to flyby Venus in
    late February of 1966 and return the first close-up images of the
    planet.  VENERA 3 was designed to achieve another space first for the
    Soviet Union:  The actual soft landing of a vehicle on the Venerean
    surface.

        The VENERA 3 craft held a ninety-centimeter (35.4-inch) lander
    capsule weighing 383 kilograms (844 pounds).  Once entry into the
    planet's dense atmosphere had been accomplished, the spherical probe
    would analyze the surrounding air while descending to the surface
    dangling beneath a parachute.  On the ground, the lander would relay
    the first direct measurements from Venus' crust back to Earth for
    the life of its batteries.

        A third member of the series, possibly a second lander, exploded
    in its Earth parking orbit on November 23 and decayed sixteen days
    later.  What would have been VENERA 4 was subsequently designated
    COSMOS 96 and kept out of the public spotlight, like so many other
    Soviet space failures.

        VENERA 2 and 3 glided to their alien destination through the first
    months of 1966, taking measurements of the interplanetary environment
    along the way.  Then, on February 27, just before its closest approach,
    VENERA 2 reported a rapid increase in temperature and went permanently
    silent.  None of the planned planet images were returned.  VENERA 2
    sailed past Venus 23,950 kilometers (14,370 miles) from the planet's
    center to join its fellow spacecraft in heliocentric orbit.

        Two days later, VENERA 3 arrived on the scene, aimed almost
    directly for the heart of the veiled world.  As the vehicle neared its
    time to separate the lander from the cylindrical flyby bus, communi-
    cations were suddenly lost.  Apparently the heating problem which had
    ended the counterpart craft's usefulness also brought about VENERA 3's
    demise.

        It is not known if the lander ever broke away from the main bus.
    It is likely that the entire vessel entered Venus' atmosphere.  Though
    it is also unknown if the probe actually reached the planet's surface
    or was destroyed from heat friction with the atmosphere, VENERA 3 is
    generally credited with being the first spacecraft to land on another
    planet.  In commemoration of this event, the probe carried a tradi-
    tional metal globe of its home world, Earth.

        The theory that VENERA 2 and 3 succumbed to overheating is not
    very surprising.  Venus averages forty-two million kilometers (twenty-
    six million miles) closer to the Sun than Earth and receives twice the
    amount of solar radiation as does our planet.  MARINER 2 was almost
    lost several times during its journey in 1962 due to the Sun's mag-
    nified heat.

        Although the VENERAs were kept from completing their main tasks,
    the probes did prove that the Soviets could at least deliver working
    spacecraft to the vicinity of Venus.  Additionally, Soviet plans for
    exploring the nearest planet were revealed to be far advanced over
    contemporary projects from the United States.

        Testing the Waters

        In the months after the premature end of the VENERA 2 and 3
    mission, the Soviets regained some of their dominance in space
    exploration.  LUNA 9 and 10 became the first vehicles to respec-
    tively soft land upon and orbit Earth's moon in February and April
    of 1966, racing ahead of similar American attempts in preparation
    for placing humans on Luna by 1970.  By the close of 1966, two more
    Soviet lunar orbiters and another lander were to follow.

        The next launch window to Venus began in June of 1967.  Twelve
    days into the month, a MOLNIYA rocket delivered a spacecraft named
    VENERA 4 on its way to the Soviets' latest encounter with Venus.
    Essentially, VENERA 4 was an improved version of the VENERA 3 mission
    profile.  Another possible Venus lander, COSMOS 167, failed to leave
    the Earth parking orbit it was placed in on June 17 and decayed on
    the twenty-fifth.

        Two days after the launch of VENERA 4, the United States also
    took advantage of the Venerean launch window with its fifth MARINER
    spacecraft.  Originally the backup vehicle for the MARINER 4 Mars
    probe, the American entry was modified for a mission to the much
    warmer vicinity of Venus.  Though MARINER 5 carried neither cameras
    nor an entry capsule, the flyby craft was fitted with a number of
    instruments for making a thorough analysis of the Venerean atmosphere
    and surrounding environment.  The American probe was scheduled to
    arrive at Venus just one day after VENERA 4, where the two voyagers'
    data would later be compared.

        The design of the VENERA 4 lander contained some interesting
    revelations, not only in the level of current Soviet space technology,
    but also where Soviet scientists stood in their views on conditions at
    Venus.  One of the more interesting features about the lander capsule
    was its ability to float in a liquid, in case the capsule encountered
    a Venerean ocean.  VENERA 4 was also built to withstand an atmospheric
    pressure roughly equivalent to twenty times that of Earth's at sea
    level, or twenty bars.

        Despite the information returned five years earlier by MARINER 2
    and the subsequent radio telescope scans of the planet, some Soviet
    scientists remained uncertain as to exactly what lay beneath Venus'
    cloud layers.  Hope sprung eternal for the discovery of a world
    beyond Earth that was friendly to life, even in rudimentary form.

        After a single course correction in late July of 1967 to ensure
    an impact, VENERA 4 reached Venus on October 18.  The lander separated
    from the main spacecraft bus upon arrival, both vehicles aimed into
    the night side of the planet.  The bus was destroyed by the heat from
    air friction with its fast entry into the Venerean atmosphere, but not
    before returning valuable information on the conditions surrounding
    Venus.  Among the more important data from the bus were a lack of
    any detectable radiation belts or magnetic fields.  A weak corona of
    hydrogen particles was found circling ten thousand kilometers (sixteen
    thousand miles) above the planet.

        Meanwhile, VENERA 4's lander capsule plowed on into the planet's
    atmosphere at a speed of ten kilometers (sixteen miles) per second,
    generating friction heat up to eleven thousand degrees Celsius
    (19,832 degrees Fahrenheit), twice as hot as the photosphere of
    the Sun!  Thanks to its protective heat shield and sturdy structure,
    the capsule was able to survive these extremes.

        Dropping deeper into the thickening soup of Venus' atmosphere, the
    capsule was slowed to a velocity of three hundred meters (990 feet)
    per second.  At this point, the lander's top cover was ejected and a
    braking parachute emerged to arrest the craft even further, down to a
    speed of ten meters (thirty-three feet) per second.  Having served its
    purpose, the braking parachute then made way for the main parachute,
    which let the capsule drift towards the surface.  Instruments snapped
    into activity and the capsule began taking the first direct atmospheric
    readings of Venus for ninety-four minutes, until the probe's signals
    abruptly ceased.

        At first, Soviet technicians reported that VENERA 4 had trans-
    mitted all the way to the Venerean surface.  Data on the atmosphere
    indicated it was composed primarily of carbon dioxide, with only
    traces of oxygen and water vapor.  Nitrogen, previously thought to
    be a major component of Venus' air, could not be detected.  Other
    data seemed to show that the surface air pressure equaled fifteen
    to twenty-two Earth atmospheres, with an average temperature of 280
    degrees Celsius (536 degrees Fahrenheit).

        The next day, America's MARINER 5 flew by the veiled planet from
    a distance of just 3,991 kilometers (2,480 miles).  For twenty-six
    minutes the craft's flight path took it behind Venus as viewed from
    Earth.  During this time, MARINER's radio signals cut through the
    planet's atmosphere on their way to Earth, displaying intricate
    details in the process.

        The Data Conflicts

        Once the MARINER data were received by its mission controllers and
    properly analyzed, some surprising discoveries were made which were
    contrary to the information from VENERA 4.  According to the American
    space probe, Venus' surface pressure was far greater than recorded by
    either its Soviet counterpart or from earlier estimates, being roughly
    equivalent to seventy-five to one hundred Earth atmospheres.  The
    ground temperature was also much higher, a sizzling 527 degrees
    Celsius (981 degrees Fahrenheit).

        MARINER 5 discovered other differences between Venus and Earth:
    The solar wind was deflected around Venus by its encompassing iono-
    sphere, rather than by any significant magnetic field as happens with
    Earth.  It appeared that Venus' creeping rotation and possible lack
    of a liquid iron core were major contributors to the absence of a
    planetary magnetic field.  The mass of Venus was refined to 81.5
    percent of Earth's.  An object weighing forty-five kilograms (one
    hundred pounds) on Earth would tip the scales on Venus at forty-one
    kilograms (ninety-one pounds).

        The Soviets initially replied to the conflicting data that VENERA
    4 must have landed on the summit of a very high mountain, in order to
    explain the lower pressure and temperature readings from their probe.
    Eventually, though, it had to be concluded that VENERA 4 did not sur-
    vive its descent to the surface.  The capsule was probably crushed at
    a height of twenty-seven kilometers (sixteen miles) by the increasing
    atmospheric pressure, with the top of the craft caving in first.  Most
    likely, VENERA 4 did ultimately reach the planet's crust, but only as
    so much scrap metal.  Venus had taught a hard lesson that its surface
    pressure and temperature were much higher than originally believed.

        Although VENERA 4 did not accomplish its main goal of reaching
    the Venerean surface intact, the on-site atmospheric measurements were
    priceless to scientists.  The high readings of carbon dioxide found by
    the VENERA probe gave the initial clues as to why Venus is so alarm-
    ingly hot.  This colorless gas is excellent at trapping the radiation
    received from the Sun and keeping it from escaping the planet back into
    space.  However, carbon dioxide alone could not hold in such intense
    heat for long.  More missions would be needed to learn what the other
    key ingredients were.

        One could not call the VENERA 4 mission a failure, despite its
    premature demise.  The very fact that the Soviets had attempted to
    land a vehicle on another planet just ten years after they had placed
    the first satellite into Earth orbit was an astounding accomplishment
    in its own right.  Most importantly, VENERA 4's tandem investigation
    of Venus with MARINER 5 gave their parent nations a good indication
    of how much valuable information could be learned about space through
    mutual cooperation.

        The Final Steps

        Since the launch window of 1961, the Soviet Union had not passed
    up a single attempt at a mission to Venus.  The window of 1969 was to
    be no exception.  However, enough had been learned about the shrouded
    world in those eight years to prove that Venus was quite hostile to an
    invading spacecraft from Earth.  Any future expeditions to Venus had
    to be fortified against crushing pressures and melting temperatures,
    amongst a host of unknown factors.

        The relatively short period since the 1967 Venus launch window did
    not allow the Soviets enough time to develop a vehicle that would be
    tough enough.  Instead, they opted to send one more mission with their
    existing VENERAs to venture further into the planet's dense atmosphere
    before the inevitably destructive end above Venus' broiling surface.
    A VENERA which could survive on Venus' rocky face would have to wait
    for the next window.

        Just seven months before the United States would deliver the first
    astronauts to the surface of Earth's moon with the historic flight of
    APOLLO 11, the two latest entries in the Soviet exploration of Venus
    were launched into deep space.  VENERA 5 lifted off from Tyuratam on
    January 5, 1969, followed by VENERA 6 five days later.  For the first
    time, a multiple Soviet Venus probe mission did not lose any known
    spacecraft members during launch or in Earth orbit.  This success
    would not be duplicated again until 1975.

        After one mid-course correction each during their five-month
    interplanetary journeys, VENERA 5 and 6 arrived at Venus just one day
    apart.  On May 16, VENERA 5 injected its lander capsule into Venus'
    atmosphere.  The capsule plunged in at a greater speed than did VENERA
    4's lander two years earlier.  These newest VENERA capsules were given
    some modifications against the planet's harsh environment.  Among the
    changes were smaller parachutes, which helped the landers drop faster
    towards the Venerean surface.

        VENERA 5 returned atmospheric data to Earth for fifty-three
    minutes, descending for thirty-six kilometers (twenty-two miles)
    until being flattened by the surrounding pressure just twenty-four
    to twenty-six kilometers (fourteen to sixteen miles) above the hot
    landscape.  The VENERA 5 data was extrapolated to indicate that the
    surface temperature and pressure beneath the spacecraft's descent
    path was 530 degrees Celsius (986 degrees Fahrenheit) and 140 Earth
    atmospheres, respectively.  The capsule also carried a photometer
    device to examine the amount of light below Venus' clouds.  One light
    reading of twenty-five watts per square meter was recorded just four
    minutes before the lander ceased transmitting.

        VENERA 6 came upon the scene the next day, releasing its capsule
    from the main bus some twenty-five thousand kilometers (fifteen thou-
    sand miles) from Venus.  The VENERA 6 lander lasted for fifty-one
    minutes in the dark of the planet's night side, eventually collapsing
    just as its twin probe did, but at an improved altitude of between ten
    and twelve kilometers (six and eight miles) from the ground.  Though
    the atmospheric constituents relayed by both landers generally agreed
    with the data from VENERA 4, traces of nitrogen were detected this time.

        The temperature and pressure readings returned by VENERA 6 were
    puzzling, however.  The robot's measurements seemed to indicate that
    the crust below was just four hundred degrees Celsius (752 degrees
    Fahrenheit) warm and pressed down by an atmosphere only sixty times
    greater than Earth's, much lower than previous readings.  For a while
    Soviet scientists tried the same "high mountain" excuse for the
    contrasting information that they used with the VENERA 4 lander data.
    This hypothesis was soon rejected in favor of the possibility that
    VENERA 6 had suffered some sort of instrument malfunction during its
    operation, thus the inconsistent readings.

        Later explorations of Venus have since shown that the region the
    two Soviet probes were aimed for, Tinatin Planitia, lies just below
    the planet's mean radius, discrediting the high mountain hypothesis.

        The Surface at Last

        Nineteen Seventy was a golden year for the Soviet Union and their
    growing space program.  In Earth orbit, the cosmonaut crew of SOYUZ 9
    broke the two-week manned space endurance record held by the crew of
    America's GEMINI 7 since 1965.  Earth's moon was the location of
    several more major Soviet accomplishments:  On September 24, LUNA 16
    returned to its home world with the first lunar soil samples taken
    by an automated probe.  Two months later, LUNA 17 carried the first
    unmanned rover, LUNOKHOD 1, to the lunar surface.  The multi-wheeled
    robot spent the next year exploring the Sea of Rains.

        The shining planet Venus was also remembered during that year.
    On August 17 and 22, two MOLNIYA boosters placed identical payloads
    into Earth orbit.  The first one went on to the second planet from
    the Sun and became known as VENERA 7.  The second payload failed
    to leave the vicinity and was called COSMOS 359, where it remained
    until atmosphere entry on November 6, 1970.

        VENERA 7 was the hardiest of the Soviet Venus probes yet built.
    Its creators wanted this vessel to land on the planet's surface in
    working order.  As a result, the spacecraft became much heavier than
    its predecessors.  The entry capsule alone weighed about five hundred
    kilograms (1,100 pounds), due to modifications based on information
    supplied by VENERAs 4 through 6.  The VENERA 7 lander could withstand
    temperatures up to 540 degrees Celsius (1,004 degrees Fahrenheit) and
    pressures equal to 180 bars for at least ninety minutes.

        The egg-shaped capsule was to be kept cooled at minus eight
    degrees Celsius (17.6 degrees Fahrenheit) by a refrigeration system in
    the main bus until its release at the planet, to guard against Venus'
    intense heat for as long as possible.  A smaller parachute was made to
    quicken the capsule's fall through the turgid Venerean air.  Shock
    absorbers were added to cushion the impact with the alien soil.  There
    were fewer external openings and more insulation on the small vehicle,
    and its instrument compartment was hermetically sealed.

        VENERA 7 performed two mid-course corrections during its flight
    through space - another first in the Soviet Venus program - before
    arriving at the veiled planet on December 15, 1970.  Unlike the
    earlier VENERA entry profiles, the VENERA 7 lander did not break
    from the main bus until both craft were entering the atmosphere,
    probably to extend the capsule's cooling period.

        Sixty kilometers (thirty-six miles) above the planet, the vessel's
    main parachute popped free and the probe began transmitting informa-
    tion about the thick night air around it.  Then, thirty-five minutes
    later, VENERA 7 suddenly went silent.  Without any warning, something
    had apparently destroyed the capsule.

        Soviet controllers back on Earth were shocked.  They had thought
    for certain that this time every possible contingency about Venus had
    been accounted for with room to spare.  Fortunately the controllers had
    kept tracking and recording the mission even after the apparent signal
    loss.  Several weeks later, a very pleasant discovery was made during
    a search through the recording tapes:  VENERA 7 had reached the
    Venerean crust intact and continued to send data for twenty-three
    minutes from the southwestern section of Tinatin Planitia.

        It seems the capsule had somehow been knocked over upon landing,
    causing its transmitter antenna to point in an unfavorable direction.
    The lander's signal strength was only one percent of what it was during
    the descent through the atmosphere.  The lander's transmissions became
    almost indistinguishable from the regular background radio noise.

        While it may not have been very graceful, VENERA 7 had achieved
    yet another victory for the Soviet Union:  The first successful landing
    of a functioning vehicle on another planet.

        In addition to its historical accomplishment, VENERA 7 confirmed
    the numerous analyses of Venus' environment from previous Soviet and
    American explorations during its brief lifetime.  The temperature at
    Tinatin Planitia was reported to be 475 degrees Celsius (887 degrees
    Fahrenheit), give or take twenty degrees.  A bare chunk of lead placed
    on the planet would melt.  Air pressure ninety times greater than
    Earth's at sea level (give or take fifteen atmospheres) engulfed the
    small probe.  Existing on Venus was equivalent to being 990 meters
    (3,300 feet) under the oceans of Earth, only much warmer and drier.
    No other member of the terrestrial family of planets held such high
    surface temperatures and pressures.

        The second planet from the Sun, once thought to be a goddess of
    beauty from its brilliant appearance in Earth's night sky, was finally

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End of Space Digest Volume 16 : Issue 152
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