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Electronic Journal of the ASA (EJASA) - September 1992
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Date: Tue, 01 Sep 1992 16:09
Date: Tue, 01 Sep 1992 16:09
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THE ELECTRONIC JOURNAL OF
THE ASTRONOMICAL SOCIETY OF THE ATLANTIC
Volume 4, Number 2 - September 1992
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TABLE OF CONTENTS
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* ASA Membership and Article Submission Information
* The Great Moon Race: The Long Road to Success - Andrew J. LePage
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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.
asa@chara.gsu.edu
ASA BBS: (404) 564-9623, 300/1200/2400 Baud.
or telephone the Society Recording at (404) 264-0451 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
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klaes@verga.enet.dec.com
or - ...!decwrl!verga.enet.dec.com!klaes
or - klaes%verga.dec@decwrl.enet.dec.com
or - klaes%verga.enet.dec.com@uunet.uu.net
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
107 days.
Contact with VENERA 3, launched on November 16, was lost on March
1 just as it was to drop a probe into the Venusian atmosphere 105 days
after launch. Both VENERA probes failed due to overheating caused
either by an inadequate thermal control system or an outright failure
of it. A third probe, KOSMOS 96, launched on November 23, never made
it out of Earth orbit due to a malfunction in the MOLNIYA's escape
stage.
The planetary compartment design that worked so well on ZOND 3
would never fly to the planets again, despite the fact it could record
over an order of magnitude more image and spectroscopic data than any
planetary mission the Americans were to fly until the launch of the
MARINER 6 and 7 Mars probes in 1969.
Soviet lunar landing attempts resumed on the eighth anniversary
of the launch of SPUTNIK 1, October 4, 1965, with the launch of
the 3,316-pound (1,506-kilogram) LUNA 7. The following day, the
spacecraft successfully performed a mid-course correction maneuver.
On October 7, as LUNA 7 was nearing the Moon, its retrorockets fired.
But before it could reach the surface, the spacecraft exhausted its
fuel supply and crashed at 9 degrees north, 49 degrees west. There
were some unconfirmed reports that some signals from the lander were
briefly received after this crash landing, but no usable data were
extracted.
The November launch window to the Moon was skipped to allow
the launch of the three ill-fated Venus probes. LUNA 8 was finally
launched on December 3, but instead of proceeding into a parking orbit
inclined about 65 degrees to the equator - as had every previous Soviet
planetary and second generation lunar probe - LUNA 8 was placed into a
parking orbit inclined 51.9 degrees to the equator. Such an orbit
makes better use of Earth's rotation to boost a payload into orbit and
would become the standard parking orbit for all Soviet space probes
afterwards. As a result, about 100 pounds (45 kilograms) of extra
payload could be sent towards the Moon.
LUNA 8 would need this increased performance margin. Weighing in
at 3,418 pounds (1,552 kilograms), LUNA 8 was the heaviest probe of
the series. Obviously the incremental improvements being made to
the second generation LUNA were slowly increasing its launch weight
nearly to the payload limits of the MOLNIYA launch vehicle. Like its
predecessors, it made a mid-course correction the day after launch.
After a flight of 83 hours, LUNA 8 passed the 40-mile (64-kilometer)
altitude mark and the retrorockets were ignited. Unlike LUNA 7, the
retrorockets started to fire seconds too late and LUNA 8 crashed with
its engines still blazing away west of the crater Kepler at 9.12
degrees north, 63.30 degrees west.
So ended 1965: The Americans had two spectacular successes in two
tries, while the Soviets had only one successful photographic flyby
and five failed landing attempts. As it would turn out, 1966 would be
a much better year for Soviet lunar exploration.
Summary of Lunar Probe Launches, 1964-1965
_____________________________________________________________________
Name Launch Country Weight Launch
Date lbs (kg) Vehicle
_____________________________________________________________________
RANGER 6 Jan 30, 1964 US 803 (365) ATLAS-AGENA B
Failed photographic lunar impact attempt
(Unannounced) Feb/Mar, 1964? USSR 3,135 (1,420)? MOLNIYA
Possible failed lunar hard landing attempt
(Unannounced) Apr 20, 1964 USSR 3,135 (1,420)? MOLNIYA
Possible failed lunar hard landing attempt
RANGER 7 Jul 28, 1964 US 806 (366) ATLAS-AGENA B
Photographic lunar impact
RANGER 8 Feb 17, 1965 US 807 (366) ATLAS-AGENA B
Photographic lunar impact
A-C 5 Mar 2, 1965 US 2,000 (900) ATLAS-CENTAUR
Unsuccessful deep space launch vehicle test
KOSMOS 60 Mar 12, 1965 USSR 3,150 (1,476)? MOLNIYA
Failed lunar hard landing attempt
RANGER 9 Mar 21, 1965 US 808 (367) ATLAS-AGENA B
Photographic lunar impact
LUNA 5 May 9, 1965 USSR 3,250 (1,476) MOLNIYA
Failed lunar hard landing attempt
LUNA 6 Jun 8, 1965 USSR 3,175 (1,442) MOLNIYA
Failed lunar hard landing attempt
ZOND 3 Jul 18, 1965 USSR 2,100 (960)? MOLNIYA
Photographic flyby and engineering test
A-C 6 Aug 11, 1965 US 2,084 (946) ATLAS-CENTAUR
Deep space launch vehicle test w/simulated payload
LUNA 7 Oct 4, 1965 USSR 3,316 (1,506) MOLNIYA
Failed lunar hard landing attempt
LUNA 8 Dec 3, 1965 USSR 3,417 (1,552) MOLNIYA
Failed lunar hard landing attempt
_____________________________________________________________________
Notes: Probe names given in () are used if no official name exists.
Weights given are the launch weights of the probes and do
not include any additional equipment that may have been
carried by the escape stage.
_____________________________________________________________________
Bibliography -
Baker, David, THE ROCKET, 1978
Burrows, William E., EXPLORING SPACE: VOYAGES IN THE SOLAR SYSTEM
AND BEYOND, 1990
Gatland, Kenneth, ROBOT EXPLORERS, 1972
Gatland, Kenneth, THE ILLUSTRATED ENCYCLOPEDIA OF SPACE TECHNOLOGY,
1988
Heacock, Raymond L., "RANGER: Its Mission and Its Results", TRW
SPACELOG, Summer 1965
Hujsak, Edward J., "The Bird that Did Not Want to Fly", SPACEFLIGHT,
March 1992 (BIS)
Johnson, Nicholas, HANDBOOK OF SOVIET LUNAR AND PLANETARY EXPLORATION,
1979
LePage, Andrew J., "The Mystery of ZOND 2", JOURNAL OF THE BRITISH
INTERPLANETARY SOCIETY (JBIS), to be released. See also the EJASA for
April 1991.
Lipsky, Yuri N., "ZOND 3 Photographs of the Moon's Far Side", SKY &
TELESCOPE, December 1965
Mirabito, Michael M., THE EXPLORATION OF OUTER SPACE WITH CAMERAS,
1983
Schurmeier, H. M., "Lunar Exploration", LUNAR MISSIONS AND EXPLORATION,
1964
Schurmeier, H. M., R. L. Heacock, and A. E. Wolf, "The RANGER Missions
to the Moon", SCIENTIFIC AMERICAN, January, 1966
Von Braun, Wernher and Fredrick I. Ordway III, HISTORY OF ROCKETRY
AND SPACE TRAVEL, 1966
Watts, Raymond N., Jr., "The Best Lunar Photographs Yet", SKY &
TELESCOPE, September 1964
Watts, Raymond N., Jr., "CENTAUR Flies Successfully", SKY & TELESCOPE,
January 1964
Watts, Raymond N., Jr., "RANGER Program Reduced", SKY & TELESCOPE,
February 1964
Watts, Raymond N., Jr., "RANGER 6 Reaches Moon", SKY & TELESCOPE,
March 1964
Watts, Raymond N., Jr., "Soviet Space Problems", SKY & TELESCOPE,
July 1965
Wilson, Andrew, (JANE'S) SOLAR SYSTEM LOG, 1987
"NASA's Future Spacecraft", STL SPACE LOG, September 1963
"NASA Spacecraft Programs", TRW SPACE LOG, Fall 1964, Fall 1965
"Planetary and Lunar Notes from Prague", SKY & TELESCOPE, January 1968
"Spacecraft Details", TRW SPACE LOG, Summer 1964, Summer 1965, Winter
1965-1966
"United States Launch Vehicles", TRW SPACE LOG, Spring 1964
"The U.S. Space Program: A Chronology", STL SPACE LOG, March 1963
MAJOR NASA LAUNCHES, KSC Historical Report No. 1A, circa 1987
TWELFTH SEMIANNUAL REPORT TO CONGRESS (NASA), July 1 - December 31,
1964
14TH SEMIANNUAL REPORT TO CONGRESS (NASA), July 1 - December 31, 1965
About the Author -
Andrew J. LePage is a member of the Boston Group for the Study
of the Soviet Space Program, Krasnaya Orbita. In addition to his
interests in astronomical and space related topics, Andrew has been
a serious observer of the Soviet (now C.I.S.) space program for over
one decade.
Andrew is the author of the following EJASA articles:
"Mars 1994" - March 1990
"The Great Moon Race: The Soviet Story, Part One" - December 1990
"The Great Moon Race: The Soviet Story, Part Two" - January 1991
"The Mystery of ZOND 2" - April 1991
"The Great Moon Race: New Findings" - May 1991
"The Great Moon Race: In the Beginning..." - May 1992
"The Great Moon Race: The Commitment" - August 1992
THE ELECTRONIC JOURNAL OF THE ASTRONOMICAL SOCIETY OF THE ATLANTIC
September 1992 - Vol. 4, No. 2
Copyright (c) 1992 - ASA
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