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Date: Wed,  2 Sep 92 05:02:19
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Space Digest                Wed,  2 Sep 92       Volume 15 : Issue 156

Today's Topics:
        Electronic Journal of the ASA (EJASA) - September 1992

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Date: Tue, 1 Sep 1992 18:18:59 GMT
From: Larry Klaes <[e-mail]>
Subject: Electronic Journal of the ASA (EJASA) - September 1992
Newsgroups: sci.astro,sci.space,sci.geo.geology,sci.misc

                          THE ELECTRONIC JOURNAL OF
                  THE ASTRONOMICAL SOCIETY OF THE ATLANTIC

                     Volume 4, Number 2 - September 1992

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

                              TABLE OF CONTENTS

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

          * ASA Membership and Article Submission Information

          * The Great Moon Race: The Long Road to Success - Andrew J. LePage

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

                         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 - Don Barry
        Vice President - Nils Turner
        Secretary - Ingrid Siegert-Tanghe
        Treasurer - Mike Burkhead
        Directors - Bill Bagnuolo, Eric Greene, Tano Scigliano
        Council - Bill Bagnuolo, Bill Black, Mike Burkhead, 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 anonymous FTP
    at chara.gsu.edu

        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) 1992
    by the Astronomical Society of the Atlantic, Incorporated.


                THE GREAT MOON RACE: THE LONG ROAD TO SUCCESS

            Copyright (c) 1992 by Andrew J. LePage

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

        As 1962 was drawing to a close, the situation with the American
    Moon program looked bleak.  The failure of RANGER 5 was NASA's sixth
    consecutive lunar mission failure in three years.  Only seventeen
    months after President John F. Kennedy committed the United States to
    landing a man on Earth's Moon with Project APOLLO, it was beginning to
    look as though the Americans would never make it.  If they could not
    get a simple unmanned probe to the Moon in working order, how could
    they hope to pull off the much more complicated mission of a manned
    lunar landing?

        Investigations into the failure of the RANGER program started on
    October 30, 1962.  Over the course of the next month, several groups
    inside NASA and out examined every aspect of the RANGER project in an
    attempt to pin down the causes of the failures and recommend changes.
    On November 30, NASA Headquarters released the findings of its inquiry:
    In brief, the report recommended streamlining management and changing
    the mission goals to be more in line with the needs of APOLLO.  This
    meant concentrating on lunar imaging and dropping all other experiments
    on the Block III RANGER.

        The report also called for a thorough re-evaluation of the RANGER
    design, modifying vulnerable systems and the inclusion of more backup
    systems.  The Jet Propulsion Laboratory (JPL) would be required to use
    outside contractors to build the three advanced Block IV RANGERs then
    being contemplated, instead of in-house as was the case with the first
    three Blocks.  More extensive testing of systems and better quality
    control for components were recommended.

        Most of all, the report called for the immediate abandonment of
    sterilization.  Sterilization was pinpointed as the cause of many of
    RANGER's system failures and it was now felt to be unnecessary, given
    that the hostile lunar environment was unlikely to harbor any indigenous
    life forms.  Unless these changes were made, the Block III RANGERs were
    likely to suffer the same fate as its predecessors.  With these recom-
    mendations in hand, JPL set about redesigning and rebuilding the Block
    III RANGERs.  The scheduled launch of what would be RANGER 6 was
    delayed until late 1963.

        A Change in Plans

        As a result of fears that JPL's problems with RANGER could recur
    in its SURVEYOR program, and because of the continuing development
    problems with the ATLAS-CENTAUR rocket, NASA Headquarters began to
    examine possible alternatives to SURVEYOR.  Langley Research Center
    was quietly directed by Headquarters in 1962 to examine the
    possibility of using a lightweight lunar orbiter launched by the
    improved ATLAS-AGENA D to perform a photographic mapping mission in
    place of the heavier SURVEYOR B orbiter.  Any more major delays in
    either the SURVEYOR or ATLAS-CENTAUR programs could severely impact
    the schedule of the all-important APOLLO program.  High resolution
    photographs of potential landing sites were urgently needed.

        The studies conducted indicated that it was feasible to build a
    small lunar orbiter that would provide the needed lunar photographs.
    By March of 1963, the basic design for LUNAR ORBITER was completed and
    the project approved.  On August 30, the newly created LUNAR ORBITER
    Project Office at Langley issued a request for proposals for its new
    lunar project.  The goal was to build an orbiter that could image
    potential APOLLO landing sites five degrees north and south of the
    equator between 45 degrees east and west longitude with a resolution
    of one meter (3.3 feet).  The first flight was expected in 1966.

        NASA had similar concerns about the lander portion of the SURVEYOR
    program.  In 1963, JPL began studies on an ATLAS-AGENA D launched
    Block V RANGER that would carry a small soft lander built by Northrop.
    This option, as it turned out, was never exercised and was dropped
    along with the advanced Block IV RANGER by the end of 1963, partially
    for budgetary reasons.

        With its orbiter mission deleted, JPL's SURVEYOR program continued
    by concentrating on building a lunar lander.  The program's goals
    were now altered to directly support APOLLO.  SURVEYOR would be used
    as an engineering tool to develop the techniques needed to land on
    the Moon.  At the end of 1963, a total of seven flights were planned.
    The first four would be test flights, while the last three would be
    operational.  The first SURVEYOR flight was still optimistically
    targeted for late 1964.  Options for additional flights of heavier
    and more advanced SURVEYOR landers that would incorporate more of the
    originally planned experiments and possibly a small rover were still
    being considered.  For this it would be required that the usable
    payload of the launch vehicle could be increased sufficiently.

        Progress with SURVEYOR's launch vehicle, the ATLAS-CENTAUR,
    continued at a steady pace during 1963.  The second test launch,
    ATLAS-CENTAUR 2, finally occurred during the afternoon of November 11
    after months of delays.  The goal of this flight was to simply get into
    orbit.  No second burn of the CENTAUR's advanced, hydrogen burning
    RL-10 engines was being considered on this flight.  The five-ton (4.5
    metric ton) CENTAUR was successfully placed into a lofty 303 by 1,093-
    mile (488 by 1,759-kilometer) orbit without any major problems.  Much
    work remained to be done to perfect this fickle machine, but at last
    there seemed to be a light at the end of the tunnel.

        The New and Improved RANGER

        The improved Block III RANGER was finally ready by the end of
    1963.  Much had been changed from the previous design.  The RANGER
    hexagon-shaped bus was similar to previous models with some notable
    exceptions.  First, the bus' framework was now made of aluminum due
    to its better thermal characteristics.  A second battery to provide
    additional backup power was added.  The course correction system was
    enlarged to provide a 135-mile per hour (60-meter per second) velocity
    change capability; a one-third increase over the Block II RANGER.  The
    sequencer was redesigned to incorporate components which were not heat
    sterilized.  This included features that increased the chances of a
    successful mission in case of equipment failure.  A second, independent
    attitude control jet system was added for redundancy.

        The bus was also fitted with new rectangular-shaped solar panels
    similar to the ones carried by the MARINER 2 Venus probe in 1962.
    This design had portions of the panels electrically isolated from each
    other to avoid a repeat of the total solar panel failure experienced
    by RANGER 5.  All of these changes increased the weight of the Block
    III RANGER.  This prompted the deletion of every instrument except
    for the television camera package to keep the probe under 810 pounds
    (368 kilograms).

        Two independent chains of RCA-developed slow scan vidicon cameras
    were enclosed in a five-foot (1.5-meter) tall tower mounted on top of
    the bus.  Clad in polished aluminum for thermal control, the 380-pound
    (173-kilogram) cylindrical tower tapered from 27 inches (69 centimeters)
    at its base to 16 inches (41 centimeters) at the top, where the low-
    gain antenna was mounted.  The six cameras viewed the approaching lunar
    surface through a 13-inch (33-centimeter) square opening on the side of
    the tower.  Their optical axes were canted at a 28-degree angle from
    the spacecraft's long axis.  Also enclosed inside the tower were two
    independent power supplies, camera sequencers, and batteries; one set
    for each chain of cameras.  Each chain also possessed its own sixty-watt
    transmitter to independently transmit images in real time back to Earth.
    The bus still carried its own three-watt transmitter which would now
    only carry engineering telemetry.

        The first camera chain was the full scan or F chain, which
    consisted of two cameras.  One camera was fitted with a 35-millimeter
    lens, providing a 25-degree field of view, while the other used a
    76-millimeter lens with an 8.4-degree field of view.  Each camera
    would scan the entire 1,152-line vidicon once the exposure had been
    taken.  As a set, the F chain returned one image every 2.56 seconds.
    Normally the camera would be turned on by commands sent from Earth.
    If this failed, the bus' onboard sequencer would activate the package
    at a preset time.  If this failed, the F chain had its own timer that
    was activated by the spacecraft's separation from the AGENA B escape
    stage.  After 67 hours and 45 minutes of flight, the F chain would
    automatically turn on and start transmitting images.  In this way,
    even if both primary systems were to fail, at least a few hundred
    full scan images would be returned.

        Independent of the F chain was a second set of four partial
    scan vidicon cameras called the P chain.  Like the F chain, 35 and
    76-millimeter lenses were used, but only three hundred partial lines -
    about seven percent of the vidicon's face - was read and transmitted
    back to Earth.  This resulted in images with the same resolution as
    the F chain but covering a smaller area.  This was done so that images
    could be returned at a rate of five images per second in hopes of
    capturing at least a partial image a couple of tenths of a second
    before impact.  At this altitude of only one or two thousand feet (300
    to 600 meters), a resolution of one foot (0.3 meters) or better was
    possible.  If the F chain were to malfunction, the P chain could
    independently return thousands of images after receiving a command
    either directly from Earth or from RANGER's central sequencer and
    timer.

        With all these hardware changes, including redundant and more
    fault tolerant systems as well as five hundred to eight hundred hours
    of prelaunch testing, the new Block III RANGER was much more likely to
    reach its target in working order.

        The Block III mission profile was very similar to the Block II up
    until the encounter with the Moon.  Since the Block III probe did not
    have to be concerned with the site and trajectory requirements of a
    lander, the impact point could be over a much larger range of longitude
    near the lunar equator.  Typically the most easterly aim point was
    targeted at the beginning of the launch window.  The aim point then
    drifted westward by about thirteen degrees of longitude per day, so
    that the impact point would have the optimum lighting conditions.

        About one hour before impact, the spacecraft would begin its
    terminal maneuver and reorient itself.  This aims the cameras along
    RANGER's flight path towards approaching lunar surface and the high
    gain antenna is again pointed towards Earth.  Some seventeen minutes
    before impact, the F chain of cameras is commanded to warm up for
    ninety seconds.  The P chain then takes its turn and warms up.
    Finally, fourteen minutes before impact at an altitude of about
    1,200 miles (1,900 kilometers), the F chain's sixty-watt transmitter
    starts beaming images back to Earth, followed by the P chain typically
    2.5 minutes later.  Transmission would continue until the spacecraft
    impacted the lunar surface at 5,800 miles per hour (2,600 meters per
    second).  If everything worked perfectly, over 4,200 close up
    television images of the lunar surface would be transmitted.

        More Failure

        Because of various minor schedule slips, the first modified Block
    III spacecraft, RANGER A, was ready for launch by the beginning of
    1964.  Its primary targets were in the smooth equatorial mare regions,
    which were considered likely APOLLO landing sites.  On the first day
    of the launch window, the site would be a point at 8.5 degrees north
    and 21.0 degrees east in Mare Tranquillitatis, the Sea of Tranquility.
    After several short holds, RANGER 6 lifted off on its first attempt
    on January 30.  The launch and injection into a translunar trajectory
    went perfectly except for a telemetry channel that switched into an
    unscheduled mode for 67 seconds when the booster engines separated
    from the ATLAS.

        Initial tracking of RANGER 6 indicated that it would miss the Moon
    by about 600 miles (965 kilometers).  More refined calculations later
    indicated a miss of only 495 miles (796 kilometers) that was corrected
    by a one minute, seven second burn of the course correction motor
    about sixteen hours and 41 minutes after launch.  This 92.2-mile per
    hour (41.2-meter per second) change of velocity placed RANGER 6 on
    course for an impact on the western edge of Mare Tranquillitatis 40
    miles (65 kilometers) south of the crater called Ross.

        On February 2, as RANGER 6 passed the 1,290-mile (2,076-kilometer)
    altitude mark moving at 4,471 miles per hour (1,998 meters per
    second), the television cameras were switched into warm up mode with
    all systems functioning normally.  When the time came for the cameras
    to switch to full power and start returning images, however, only
    static was received.  Quickly a series of emergency commands were sent
    from Earth, but to no avail.  RANGER 6 crashed into the lunar surface
    at 9.39 degrees north, 21.51 degrees east at a speed of 5,946 miles
    per hour (2,658 meters per second) without returning a single picture.

        RANGER 6 was definitely a very successful engineering test.
    With the exception of the cameras, all systems worked perfectly.  In
    addition, the navigation accuracy was the best ever attained; the
    spacecraft impacted the Moon only 19 miles (31 kilometers) from its
    aim point and only 0.3 seconds before its post-mid-course maneuver
    predicted impact time.  Still, from the science community's and
    public's point of view, this was NASA's seventh consecutive lunar
    mission failure.  NASA Headquarters formed another board of inquiry to
    investigate this mishap.  The March launch of RANGER B was postponed
    pending the outcome of this new investigation.  The pressure was on
    NASA and JPL was fighting for its life.

        After a self-imposed hiatus, the Soviets began anew their attempts
    to reach the Moon.  In contrast to their early successes, this new
    generation of LUNA spacecraft suffered even more failures.  According
    to Western intelligence sources, the Soviets first lunar mission since
    LUNA 4 failed to reach Earth parking orbit due to a launch vehicle
    malfunction sometime around February or March of 1964.  Yet another
    LUNA was lost around April 20 due to another MOLNIYA launch failure.
    Possibly as a result of these new failures, the Soviets postponed
    additional LUNA launch attempts for almost another year while the
    bugs were worked out of the MOLNIYA.

        The NASA investigation into the failure of the RANGER 6 camera
    package was released on March 17.  The 75-page report pinned the
    problem squarely on the RCA camera package itself.  The completely
    redundant camera system was found not to be perfectly so.  There was a
    single line that carried commands to both camera chains.  Somehow a
    command was sent to the camera package during ascent that turned it
    on, hence the anomalous telemetry reading during launch.  The cameras
    were turned on and, in the relatively dense atmosphere, both camera
    power supplies arced and shorted out.

        While the source of the errant command was not known at the time,
    several changes in the RCA camera package were suggested.  These
    included changes to simplify ground testing and in-flight operation,
    telemetry system modifications to increase failure mode coverage,
    inclusion of additional noise suppression in the camera command
    circuitry, and a more rigorous prelaunch inspection of the television
    circuitry.  These changes also included an interlock that would prevent
    the cameras from being turned on during launch.  In addition, the tower
    temperature would be lowered by twenty degrees Fahrenheit (eleven
    degrees Celsius).

        While these changes would further increase RANGER's chances of
    success, the blame did not totally lie with RANGER.  It was later
    discovered that the jettisoning of the ATLAS booster engines caused
    RANGER's cameras to turn on.  When the ATLAS dropped its booster
    engines, about 400 pounds (180 kilograms) of propellant were expelled
    and ignited by the sustainer.  This small detonation had caused some
    problems during the development of the ATLAS E/F ICBM but was never
    a problem for the ATLAS D.  The detonation wave produced during the
    flight of RANGER 6 worked its way into a mechanically sealed umbilical
    door on the AGENA.  The umbilical pin that controlled the camera
    package was 0.25 inches (6 millimeters) from another pin carrying
    twenty volts.  The burning fuel vapor was conductive enough to short
    the two pins briefly, cause the camera package to turn on prematurely
    and, as a result, burn out.

        Success!

        By the summer of 1964, RANGER B had been modified and was ready to
    be launched during the next launch window in late July.  There were
    some who wanted to target RANGER B close to the impact point of RANGER
    6 to observe the crater it produced.  Unfortunately the trajectory
    constraints of this launch window would not allow an impact that far
    east.  Instead, several targets were considered for the first day of
    the launch period on July 27 along seven degrees west longitude between
    21 degrees north and 14 degrees south latitude.  The launch on this
    first day was scrubbed due to problems with the ground-based portion
    of the guidance system.  Finally, on July 28, RANGER 7 successfully
    lifted off only 7.9 seconds into its launch window aimed at 11 degrees
    south, 21 degrees west in the northwest portion of Mare Nubium.

        With a good injection burn from the AGENA B, it was calculated
    that RANGER 7 would skim over the leading edge of the Moon and impact
    on its far side.  A fifty-second course correction burn the day after
    launch brought the predicted impact point within the intended target
    area.  When RANGER 7 was 1,415 miles (2,277 kilometers) above the
    lunar surface traveling at 4,290 miles per hour (1,917 meters per
    second), the F chain cameras were placed into the ninety-second warmup
    mode followed later by the P chain.  Much to the relief of JPL and
    NASA officials, pictures from the F chain cameras started streaming
    back to Earth seventeen minutes and thirteen seconds before impact,
    followed three minutes and 33 seconds later by the P chain.

        By the time RANGER 7 plowed into the lunar surface 68 hours, 35
    minutes, and 42 seconds after launch, 4,316 pictures pictures had been
    transmitted back to Earth.  The last image, only a portion of which
    was transmitted before destruction, was made at an altitude of only
    one thousand feet (three hundred meters), showing features as small as
    three feet (one meter) across.  RANGER 7 had impacted at 10.7 degrees
    south, 20.7 degrees west, only eight miles (thirteen kilometers) from
    its aim point.  It was the first major American lunar mission success
    after almost six years of attempts.

        The pictures returned by RANGER 7 confirmed that the lunar mare
    regions are quite smooth and apparently free of major hazards for the
    APOLLO Lunar Module.  Because of the size and shape of the craters and
    the topography observed during the approach, it seemed unlikely that
    the lunar surface was coated with a deep dust layer that could bury a
    lunar lander upon touchdown, as some had feared.

        With a solid success under their belts, worked continued on
    RANGER's followup programs, LUNAR ORBITER and SURVEYOR.  On May 10,
    1964, Boeing was awarded the contract for the LUNAR ORBITER, beating
    out a Lockheed bid which had proposed a spacecraft based on its
    military reconnaissance satellite.  The 830-pound (380-kilogram) lunar
    satellite was planned to be placed into a 575-mile (925-kilometer)
    high circular orbit for its initial survey of potential APOLLO landing
    sites.  Later the orbit would be adjusted so that LUNAR ORBITER could
    swoop within 28 miles (45 kilometers) of selected target areas for
    more detailed inspections.  The imaging system that was planned
    would record images on photographic film, which would be developed
    automatically onboard, a technique first used by the Soviet Union with
    the flight of LUNA 3 in 1959.  The photographs would then be scanned
    and transmitted back to Earth over the course of ten days.  A total
    of five flights were planned starting in middle 1966 and continuing
    at quarterly intervals afterwards.

        Substantial advances also continued to be made with the SURVEYOR
    program.  Extensive testing of a prototype had been completed and
    testing of various systems was proceeding more or less on schedule.
    The weight estimate for the operational spacecraft was settling around
    2,150 pounds (975 kilograms) of which 65 pounds (30 kilograms) would
    be instrumentation.  On the three operational flights, an approach and
    two surface television cameras would be carried along with an alpha
    scattering instrument to measure soil composition, a seismograph,
    micrometeoroid detectors, and a soil dynamics experiment.  Minimal
    instrumentation would be carried on the first four test flights now
    expected sometime in 1966.

        Studies on the SURVEYOR follow on mission, known as Block II, were
    completed by late 1964.  One of the payloads still under consideration
    for this 2,600 pound (1,200 kilogram) lander was a 150-pound (70-
    kilogram) rover that could make soil bearing and topographic studies
    up to two miles (three kilometers) from the lander.  In order to lift
    this much heavier payload, studies indicated that the CENTAUR stage
    would have to be upgraded and modified to make use of a liquid
    oxygen/liquid fluorine mixture known as FLOX to replace the normally
    used liquid oxygen (LOX) oxidizer.  The inclusion of highly reactive
    liquid fluorine in the oxidizer was expected to greatly increase the
    performance of the CENTAUR.  Assuming the program was funded and the
    FLOXed CENTAUR was available, the first of as many as ten Block II
    SURVEYOR flights would take place around 1968.

        The ATLAS-CENTAUR test program was having mixed results.  ATLAS-
    CENTAUR 3, launched on June 30, 1964, failed to reach Earth orbit,
    although some tests were conducted with the CENTAUR.  ATLAS-CENTAUR 4
    was launched on December 11 into a 101 by 107-mile (163 by 172-kilometer)
    parking orbit carrying a dynamic mass model of SURVEYOR in a flight to
    test the integrity of the total system.  A secondary objective was to
    test the new upper stage's restart capability for the first time.
    While the primary objectives were met, the CENTAUR failed to reignite
    and propel itself into a simulated lunar trajectory.  The now inert
    stage fell out of orbit the following day.

        Because of the continued problems with the ATLAS-CENTAUR, the
    goals of the development program were changed to provide a direct
    ascent capability for SURVEYOR in 1966.  While such a trajectory is
    less than optimum, it did have the advantage of requiring the CENTAUR
    to fire only once, thus avoiding the problems encountered developing
    an in-flight restart capability.  The initial flights of SURVEYOR
    would be light enough and the ATLAS-CENTAUR accurate enough to make
    such a flight possible.  A parking orbit capability would be available
    later in the year and an increased lift capability would be available
    in 1967.

        The Assault Begins

        The year 1965 would witness the most intense wave of lunar probes
    since the beginning of the Space Age.  The first mission of the year
    started on February 17 with the successful launch of RANGER 8.  Like
    its predecessors, it was targeted for the most promising class of
    APOLLO landing sites, the smooth equatorial mare regions.  For this
    mission, the selected aim point was 3 degrees north, 24 degrees east
    in Mare Tranquillitatis about 130 miles (210 kilometers) south of the
    impact point of RANGER 6.

        After injection into a translunar trajectory, tracking indicated
    that RANGER 8 would miss the Moon by 1,136 miles (1,828 kilometers).
    This was negated by a 59-second mid-course correction burn at a
    distance of 99,281 miles (159,743 kilometers).  During the burn,
    however, controllers were alarmed by a loss of telemetry from the
    receding spacecraft.  Concerned about attempting any more maneuvers,
    it was decided that RANGER 8 would not perform the terminal descent
    maneuver to align RANGER's cameras with its flight path.  While this
    would smear the last few images returned by the quickly descending
    probe, it did offer the opportunity to take a swath of images over a
    wider area that would partially overlap with the early images returned

    by RANGER 7.  Stereo images would also be procured in the process.

        As the probe approached the Moon, the cameras were turned on 23
    minutes before impact, almost ten minutes before normally planned.
    The resolution of these first images was comparable with the best
    Earth-based telescopic photographs.  As RANGER 8 screamed towards its
    destruction, the robot craft continued returning a stream of pictures
    which were very similar to those returned by the previous probe.  The
    maria all seemed to have similar topography and presented no major
    problems for a landing, manned or otherwise.  RANGER 8 then crashed
    into the Moon, producing a 45-foot (14-meter) diameter crater at 2.59
    degrees north, 24.77 degrees east, only 14 miles (23 kilometers)
    southeast from its aim point.  RANGER 8 returned a total of 7,137
    pictures, the best of which showed features as small as five feet (1.5
    meters) across.  The American lunar program finally seemed to be on
    the road to success.

        On March 12, only three weeks after RANGER 8 impacted Earth's
    natural satellite, the Soviet Union launched another lunar lander.
    Unfortunately the MOLNIYA's escape stage failed to reignite and
    stranded its payload, now called KOSMOS 60, in a low 125 by 178-mile
    (201 by 287-kilometer) parking orbit.  The failed lander's orbit
    decayed five days later.

        Less than nine days later, the last Block III RANGER spacecraft
    was being prepared for launch.  Unlike its sisters, RANGER D was going
    to be targeted for scientifically more interesting sites.  The first two
    days of the lunar launch window did not offer any promising targets
    and no launch attempt was made.  A launch on March 21 would allow an
    impact in the crater Alphonsus, which had shown some signs of apparent
    selenological activity in the recent past.  A March 22 launch would
    land in the bright rayed crater Copernicus.  March 23 would allow
    Kepler to be targeted, while a launch on either March 24 or 25 would
    permit an impact near Schroter's Valley.

        As it turned out, RANGER 9 lifted off on its first attempt on
    March 21, bound for a point at 13 degrees south, 2.5 degrees west,
    located in the crater Alphonsus.  After AGENA 6007 completed its
    ninety-second injection burn, RANGER 9 was heading for a point only
    400 miles (640 kilometers) north of its target.  A 31-second burn of
    the course correction motor 38 hours, 26 minutes after launch added
    the 40.6 miles per hour (18.1 meters per second) needed to put RANGER
    9 back on course.

        As the last RANGER was hurtling towards the Moon, the probe
    aligned its cameras with its flight path.  Twenty minutes before
    impact, controllers sent commands to begin warming the cameras.
    Starting at an altitude of 1,300 miles (2,100 kilometers), RANGER 9
    began transmitting the first of 5,814 pictures.  The resolution
    steadily increased to as good as ten inches (25 centimeters) before
    the spacecraft slammed into the floor of Alphonsus at 13.3 degrees
    south, 3.0 degrees west, only four miles (6.5 kilometers) from its
    target.

        Surprisingly, the images returned by RANGER 9 indicated that while
    the lunar highlands were rougher than the maria, they were still
    smooth enough to be considered viable landing sites for future landing
    missions.  Tracking of all four Block III RANGERs also indicated that
    the Moon's geometric center was displaced from its gravitational
    center.  This fact was required to improve the accuracy of future
    lunar missions.  After six years of effort, a total of 267 million
    dollars in funding (which would be close to one billion of today's
    dollars), much heartache over six failures, and much relief on three
    successes, NASA's first major lunar exploration program was ended.
    Efforts now turned to the other two legs of NASA's unmanned lunar
    triad, SURVEYOR and LUNAR ORBITER.

        The Big Push

        With the completion of the RANGER program, lunar exploration for
    the next fourteen months was dominated by the efforts of the Soviet
    Union.  Their next launch occurred on May 9, 1965.  This time the
    MOLNIYA booster vehicle operated as intended to place the 3,250-pound
    (1,476-kilogram) LUNA 5 on a trajectory towards the Moon.  While no
    information was released on the spacecraft's design, this time there
    was no doubt of its intended mission:  It was announced that LUNA 5
    would attempt a soft lunar landing.

        A course correction the day after launch put the probe on target
    for the Moon.  After 3.5 days of travel, LUNA 5 arrived at its target.
    At an altitude of 40 miles (64 kilometers), the onboard radar
    altimeter would trigger the retrorockets to slow the probe from 5,800
    miles per hour (2,600 meters per second) to a virtual stop at the
    lunar surface.  Then, at the moment the retrorockets were to fire,
    nothing happened.  LUNA 5 crashed at 31 degrees south, 8 degrees west.

        Unphased by the loss, another probe was launched less than one
    month later.  The 3,175-pound (1,442-kilogram) LUNA 6 was launched on
    June 8 and successfully placed on a translunar trajectory.  As with
    its predecessor, LUNA 6 performed a mid-course correction the day
    after launch, after a dozen communication sessions with its controllers.
    However, unlike its sister craft, the probe malfunctioned at this point
    and the course correction engine continued to burn past its intended
    cutoff time despite desperate commands sent from controllers on Earth.
    As a result of this extra added impulse, LUNA 6 missed the Moon by
    about 100,000 miles (161,000 kilometers) and continued on into solar
    orbit.  The Soviets were robbed of another success for the eighth time
    in two years.  The new, second generation LUNA design apparently needed
    more work.

        The next lunar mission launched by the Soviets was flown by an
    entirely different type of spacecraft.  Launched on July 18, ZOND 3
    was flown as an engineering test of the same type of interplanetary
    probe unsuccessfully used on the MARS 1 and ZOND 2 missions to Mars in
    1962 and 1964 respectively and the ZOND 1 mission to Venus in early
    1964.  Some in the West have speculated that ZOND 3 was originally
    meant to be launched with ZOND 2.  The launch was canceled possibly
    because of last-minute problems, making ZOND 2 the only solo planetary
    mission the Soviets have ever launched.  With three VENERA probes
    using this same design scheduled to be launched during the next Venus
    launch window in four months, Soviet engineers apparently wanted to
    test this design one last time using this "surplus" spacecraft to
    make sure they had worked out all the bugs in the design.

        This first generation interplanetary probe consisted of two
    compartments, the orbital compartment and the planetary compartment.
    The orbital compartment was the heart of the probe.  This pressurized
    3.6-foot (1.1-meter) diameter cylinder contained the probe's control
    systems, transmitters, batteries, thermal control, and astro-orien-
    tation systems, as well as some cruise experiment electronics.  Mounted
    on top of the compartment was a 440-pound (200-kilogram) thrust KDU-414
    propellant course correction engine capable of at least two burns,
    yielding a total velocity change of about 180 miles per hour (80 meters
    per second).  Also located here was a nitrogen jet attitude control
    system to maintain control of the 12-foot (3.6-meter) long, three-axis
    stabilized probe.

        Mounted on the sides of this compartment were two solar panels
    used to recharge ZOND's batteries.  While not needed for a short
    mission to the Moon, they were vital for an interplanetary mission.
    The panels had a total span of about thirteen feet (four meters) when
    deployed.  On the ends of each panel were mounted large hemispherical
    radiators used to control the spacecraft's temperature.  On the
    anti-Sun side of the craft, a 6.6-foot (two-meter) high-gain antenna
    was mounted.  Also attached to this compartment were instruments to
    study micrometeoroids, cosmic radiation, low-frequency radio waves,
    and magnetic fields.  And like its predecessor, ZOND 2, it also
    carried a set of experimental ion thrusters for use in attitude
    control tests.

        Mounted underneath the orbital compartment was the planetary
    compartment.  This compartment would carry the instruments needed
    to study the target planet.  Starting with the flight of VENERA 3,
    launched in November of 1965, these compartments were designed to
    detach from the orbital compartment and land on the surface of Venus.
    It is highly likely that the planetary compartment of ZOND 2 was of
    similar design and meant to land on the planet Mars.  It is also
    possible that as many as four of the five unannounced failed attempts
    to reach Venus and Mars in 1962 - as well as ZOND 1 and KOSMOS 27,
    targeted for Venus in 1964 - carried similar payloads.

        The planetary compartment of ZOND 3 was different.  It was
    designed to stay attached to the orbital compartment as the spacecraft
    flew by its target.  Contained in this three-foot (0.9-meter) sphere
    were three experiments:  A photo-television system capable of taking
    either photographs or ultraviolet spectra in the 250 to 350 nanometer
    range as well as ultraviolet and infrared spectrophotometers sensitive
    to the 190 to 270 nanometer and the three to four micron wavelength
    bands, respectively.  An earlier version of this system was carried by
    MARS 1.  It was also likely carried by one of the failed Venus attempts
    in late 1962 and possibly by either KOSMOS 27 or ZOND 1, instead of a
    lander, in early 1964.  This compartment was virtually identical to
    the one carried by VENERA 2, launched in November.

        The spectrophotometers and ultraviolet spectrometer were
    originally designed to study planetary atmospheres, so they were
    of little use in a lunar mission.  The 14-pound (6.5-kilogram)
    photo-television system, however, was to be invaluable on this
    mission.  It was basically a much improved version of the system
    employed six years earlier by LUNA 3.  Images from a single
    106.4-millimeter focal length f/8 lens were focused onto one-inch
    (25.4-millimeter) film.  A total of 25 exposures of one-thirtieth or
    one one-hundredth of a second were made.  Using the same film, the
    ultraviolet spectrometer would expose the eighth, ninth, and tenth
    frames, bringing the total number of exposures up to 28.  After the
    film was exposed, it was automatically developed on board.

        The dried negatives were then scanned and transmitted back to
    Earth in one of two formats.  A quick look format broke the photograph
    into 67 lines that could be transmitted in 135 seconds.  A more
    detailed scanning of the photographs was also possible.  In this mode,
    each photograph was broken into 1,100 lines of 860 points each that
    were comparable in quality to RANGER's full scan television images.
    In this mode a single photograph could be transmitted over inter-
    planetary distances in 34 minutes.  Each image could be scanned
    multiple times to help increase the image's signal-to-noise ratio.

        For this engineering test, ZOND 3 was targeted to flyby the Moon's
    western edge and photograph most of the Moon's far side missed during
    the historic LUNA 3 mission in late 1959.  Unlike that mission, the
    lighting conditions and viewing angles were much more favorable for
    picking out details in this previously unmapped region.  After its
    successful launch by a MOLNIYA launch vehicle, ZOND 3 headed towards
    the Moon.  Since it only weighed two-thirds as much as the recent
    LUNA probes, ZOND 3 reached its rendezvous point 5,730 miles (9,220
    kilometers) above the Moon after a flight of only 33 hours.

        Starting at a distance of 7,190 miles (11,570 kilometers), ZOND 3
    took one exposure of the Moon every 134 seconds.  Images included
    not only the unmapped far side but also the near side so that newly
    discovered features could be tied into the already existing lunar
    mapping control net.  This continued as the fast-moving probe reached
    its closest point to the Moon and then receded to a distance of 6,190
    miles (9,960 kilometers).  After this 68-minute photography session,
    ZOND 3 immediately developed its film as it headed into a simulated
    trajectory to Mars - simulated since Mars was not in position for a
    low-energy encounter and would not be for another 1.5 years.

        On July 29, at a distance of 1.4 million miles (2.2 million
    kilometers), ZOND 3 was far enough for its high gain antenna to
    lock onto Earth and transmit back the recorded images to waiting
    scientists.  The images were spectacular, far superior to the ones
    returned by LUNA 3.  Details as small as three miles (five kilometers)
    across could be seen in the photographs, which showed little more than
    a cratered wasteland.  These photographs confirmed that there was a
    lack of maria on the Moon's far side compared to the familiar near
    side, which was dominated by these dark and relatively flat expanses
    of ancient, hardened lava.

        The photographs also showed no signs of Mare Parvum, which some
    observers had claimed to see near Mare Orientale during especially
    extreme librations of the Moon.  ZOND 3 discovered a new type of lunar
    feature called thalassoids.  These were the battered concave-shaped
    remnants of basins over three hundred miles (five hundred kilometers)
    across and were thought to be the precursors of maria.  For some
    reason these far side structures were never flooded with lava to form
    true maria.  The other optical instruments onboard ZOND 3 showed that
    the Moon reflected one percent of the ultraviolet radiation hitting
    its barren surface.  In contrast, the lunar surface reflected eighty
    to ninety percent in the incident infrared light, with a broad peak
    around 3.6 microns.  With these photographs in hand, the Soviets had
    mapped all but five percent of the Moon's surface.

        ZOND 3 continued to operate as it traveled further from Earth.
    On September 19, at a distance of 7.8 million miles (12.5 million
    kilometers), ZOND 3 performed a burn of its KDU-414 engine to change
    its velocity by 112 miles per hour (50 meters per second) as part of
    a simulated mid-course correction.  On October 23, at a distance of
    19.6 million miles (31.5 million kilometers), ZOND 3 successfully
    retransmitted its photographs and probably did so again at still
    greater distances.  The probe was tracked until it had receded to
    a distance of 95.4 million miles (153.5 million kilometers) in March
    of 1966, when contact was finally lost.

        It was a very successful test of this probe design.  At 225-plus
    days, ZOND 3 was also the longest-surviving Soviet lunar or planetary
    probe to date, beating the previous record holder, MARS 1, by almost
    three months.  Ironically, its Venus-bound sister probes did not fare
    as well.  VENERA 2, launched on November 12, which carried the same
    instruments as ZOND 3, failed just as it was to perform its photo-
    graphing session of Venus on February 27, 1966, after a flight of

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End of Space Digest Volume 15 : Issue 156
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