ch11.htm

<!DOCTYPE HTML>
<HTML>
<HEAD>
   <TITLE>chapter 11</TITLE>
   <META HTTP-EQUIV="Content-Type" CONTENT="text/html; charset=US-ASCII">
</HEAD>
<BODY BGCOLOR="#FFFFFF">

<DL>
   <DT><CENTER><FONT FACE="Geneva">
   <HR NOSHADE>
   SP-4206 Stages to Saturn
   <HR NOSHADE>
   </FONT></CENTER>
   
   <DD><CENTER><B><FONT FACE="Geneva">&nbsp;</FONT></B></CENTER>
   
   <DT><B><FONT FACE="Geneva">&nbsp;</FONT></B>
</DL>

<H2>11. Qualifying the Cluster Concept</H2>

<P><FONT FACE="Geneva">[<A NAME="323"></A></FONT><B><FONT
FACE="Geneva">323</FONT></B><FONT FACE="Geneva">] The Saturn I flight
tests were uniformly successful, and the unique size and complexity
of the clustered rocket made its success all the more remarkable.
Midway in the Saturn I flight test programs, Dr. F. A. Speer, Chief of
MSFC's Flight Evaluation and Operational Studies Division,
Aero-Astrodynamics Laboratory, summarized the first five flights
(which included the first live two-stage vehicle, SA-5); a summation
that turned out to be a prognosis for all 10 vehicles of the Saturn I
series. "All five flights were complete successes," Speer reported,
"both in achieving all major test missions and in obtaining an
unprecedented volume of system performance data for flight analysis."
Speer asserted, "It is correct to state that, up to this point, no
major unexpected design change had to be initiated on the basis of
flight test&mdash;thus proving the design maturity of the Saturn I
vehicle."</FONT><B><SUP><FONT
FACE="Geneva"><A HREF="notes.htm#11.1">1</A></FONT></SUP></B><FONT
FACE="Geneva"> Troubles occurred, to be sure; but they did not cause
serious delays in the mission schedules, nor serious redesign
efforts.</FONT></P>

<P><FONT FACE="Geneva">On 27 October 1961, the first Saturn lifted
from the launch pad at Cape Canaveral. All the static tests, dynamic
tests, and test firings before this first launch had pointed to a
successful mission, but until the liftoff of SA-1, no one could say
for certain that an eight-engine monster like the Saturn would really
work. The long countdown demonstrated the compatibility of the ground
support equipment, and the launch crew released the "bird" (as NASA
crews called the rockets) with no technical "hold" to mar the
mission. The SA-1 vehicle soared to an altitude of 137 kilometers and
impacted the Atlantic Ocean 344 kilometers downrange.
[<A NAME="324"></A></FONT><B><FONT FACE="Geneva">324</FONT></B><FONT
FACE="Geneva">] The postmission report verified the confidence of the
Marshall team in the structural rigidity of Saturn's airframe, and
the quartet of gimbaled outboard engines demonstrated the design
goals of vehicle control and reliability. The validity of the concept
of the clustered Saturn booster could no longer be
questioned.</FONT><B><SUP><FONT
FACE="Geneva"><A HREF="notes.htm#11.2">2</A></FONT></SUP></B></P>

<H3>Early Birds: Block I and Block II</H3>

<P><FONT FACE="Geneva">The 10 launches of the Saturn I booster
included both Block I and Block II versions. The H-1 engine was
common to all the vehicles, but a number of significant differences
distinguished Block I from Block II. The most visible distinguishing
feature for the Block I series, SA-1 through SA-4, was the absence of
aerodynamic fins on the first stage. Moreover, the Block I vehicles
did not include live upper stages. Consistent with NASA's building
block concept and the requirements for validating the clustered
concept first, these first Saturn I launches used live lower stages
only. The dummy upper stages looked like the future live versions,
had the same approximate center of gravity, and had identical weight.
Inert S-IV and S-V stages, topped by a nose cone from an Army Jupiter
rocket, brought the typical height of the Block I series to about 50
meters.</FONT></P>

<P><FONT FACE="Geneva">The flight of SA-1 was remarkable for the
small number of modifications that were required for succeeding
flights. Experience gained from successive launches inevitably
resulted in changes, but the only major difficulty that turned up
with SA-1 was an unanticipated degree of sloshing of propellants in
the vehicle's tanks. Beginning with vehicle SA-3, additional
antislosh baffles were installed, which brought this undesirable
characteristic under control. None of the Block I missions called for
separation of the upper stages after the S-I first-stage engine
cutoff, although the SA-3 and SA-4 vehicles experimentally fired four
solid-fuel retrorockets, anticipating the separation sequence of
Block II missions. Other preliminary test items on SA-4 included
simulated camera pods and simulated ullage rockets on the inert S-IV
stage. The last two vehicles also carried a heavier and more active
load of electronics and telemetry equipment. The telemetry equipment
and associated test programs varied with the goals of each mission,
but the total array of such gadgetry and the means of acquiring
information help explain not only the success of the Saturn program
but also the comparatively low number of R&amp;D flights required to
qualify the vehicle as operational.</FONT></P>

<P><FONT FACE="Geneva">The flight of SA-4 culminated with only seven
engines firing instead of eight. One of the appealing features of
clustered engines involved the "engine-out capability"&mdash;the prospect
that, if one engine quit, the remaining engines could compensate by
burning longer than planned. So NASA technicians programmed a
premature cutoff of one engine 100 seconds
[<A NAME="325"></A></FONT><B><FONT FACE="Geneva">325</FONT></B><FONT
FACE="Geneva">] into the flight. The experiment succeeded, the SA-4
performing as hoped on the remaining seven engines.</FONT></P>

<P><FONT FACE="Geneva">During this basically uneventful series of
launches, the Saturn I carried its first payloads. The missions of
SA-2 and SA-3 included one very unusual experiment, called Project
Highwater, authorized by NASA's Office of Space Sciences. The inert
S-IV and S-V stages for these launches carried 109 000 liters (30 000
gallons) of ballast water for release in the upper atmosphere. As
NASA literature stated, "release of this vast quantity of water in a
near-space environment marked the first purely scientific large-scale
experiment concerned with space environments that was ever
conducted." One of the questions apparently bothering NASA planners
was the consequences of a stage explosion in space or the necessity
of destroying one of the Saturn rockets at a high altitude. What
would happen to the clouds of liquid propellants released in the
upper atmosphere? Would there be radio transmission difficulties?
What would it do to local weather conditions? Project Highwater gave
answers to these questions. At an altitude of 105 kilometers,
explosive devices ruptured the S-IV and S-V tanks, and in just five
seconds, ground observers saw the formation of a huge ice cloud
estimated to be several kilometers in diameter, swirling above the
spent stage to a height of 145 kilometers above the sea. It was a
dramatic sight for the observers below at Cape Kennedy and marked the
first use of the Saturn launch vehicles for a purely scientific
mission.</FONT><B><SUP><FONT
FACE="Geneva"><A HREF="notes.htm#11.3">3</A></FONT></SUP></B></P>

<P><FONT FACE="Geneva">During 1964, introduction of the Saturn I
Block II vehicles marked a new milestone in large launch vehicle
development. To the casual observer, the most obvious distinction was
the addition of the eight aerodynamic fins to the lower stage for
enhanced stability in flight. As far as NASA was concerned, the most
significant feature of Block II was the addition of a live upper
stage, the S-IV, built by Douglas. Moreover, the S-IV stage also
marked the inauguration of liquid hydrogen propellant technology in
the Saturn vehicle program; six RL-10 liquid hydrogen rocket engines
supplied by Pratt &amp; Whitney were used. These engines in the upper
stage would allow orbital operations for the first time in Saturn I
launches. Above the S-IV stage, the Block II vehicles also carried
the first instrument canisters for guidance and control. The
instrument canister controlled the powered ascent of the big rocket
and carried an array of sensing and evaluation equipment for
telemetry acquisition from the ground.</FONT></P>

<P><FONT FACE="Geneva">In addition to the untried cluster of six
RL-10 liquid hydrogen engines for the S-IV, the Block II Saturns
relied on uprated, 836 000-newton (188 000-pound) thrust H-1 engines,
that gave the first stage a total thrust of slightly over 6 672 000
newtons (1.5 million pounds). Further, the new engines powered an
improved S-I first stage. The length of the propellant containers,
for instance, had been increased to provide additional propellants
for the uprated engines. Despite the added weight penalty of
[<A NAME="326"></A></FONT><B><FONT FACE="Geneva">326</FONT></B><FONT
FACE="Geneva">] the extended container length, there was
an overall gain in efficiency of the Saturn I first stage because of
numerous changes. These included, for example, weight savings through
simplification of the propellant interchange system that lessened the
amount of residual fuel and oxidizer trapped in the propellant
interchange lines. Heightened confidence in the reliability of the
H-1 engines enabled reduction of the holddown time at launch from 3.6
seconds to 3.1 seconds; this savings shifted an additional 0.5 second
of maximum boost to the powered flight phase, thereby enhancing the
vehicle's performance. Efficiency of propellant depletion was also
increased as a result of experience and numerous subsystems changes.
The first SA-1 vehicle used 96.1 percent of its fuel, for example; by
the time of the flight of SA-10, the use had reached 99.3 percent.
Payload capability was also increased by reducing the amount of
pressurants on board. The height of the Block II rockets
[<A NAME="327"></A></FONT><B><FONT FACE="Geneva">327</FONT></B><FONT
FACE="Geneva">] varied with the different missions they performed.
With a Jupiter nose cone, SA-5 was about 50 meters high, but the
remainder of the Block II vehicles, SA-6 through SA-10, carried
prototype Apollo capsules and other payloads, which stretched them to
approximately 57.3 meters.</FONT><B><SUP><FONT
FACE="Geneva"><A HREF="notes.htm#11.4">4</A></FONT></SUP></B></P>

<DIV CLASS="figure" ID="fig326a">
<IMG SRC="p326a.jpg">
<P CLASS="caption">Saturn I SA-4 rises from the launch pad on 28 March
1963. The last of the Block I vehicles, it has no aerodynamic
fins&hellip;</P>
</DIV>

<DIV CLASS="figure" ID="fig326b">
<IMG SRC="p326b.jpg">
<P CLASS="caption">&hellip;as does SA-5, which sits on the pad.</P>
</DIV>

<DIV CLASS="figure" ID="fig326c">
<IMG SRC="p326c.jpg">
<P CLASS="caption">An artist's conception of S-IV stage separation in
space, with the six RL-10 engines kicking the payload into orbit.</P>
</DIV>

<P><FONT FACE="Geneva">Although electronic instrumentation and
telemetry provided reams of pertinent information on the health and
performance of the rocket during a mission, flight-test personnel
needed visual documentation as well. For this reason, the Saturn
vehicles all carried an invaluable array of visual instrumentation
equipment. The Block II series continued the visual instrumentation
that was begun during Block I flights. MSFC engineers wanted very
much to know about the behavior of propellants within the vehicle
during flight, so a number of different visual instrumentation
systems were carried. Great attention was given to on-board
television systems. Work with on-board TV began at MSFC early in 1959
under the cognizance of the Astrionics Division. Research emphasized
the development of a compact and extremely rugged camera to stand up
under the punishment of liftoff, boost phase, and free trajectory
coast in extreme temperature and pressure environments. MSFC tried
out the system on 31 January 1961 on the Mercury-Redstone that
carried the chimpanzee Ham. The real-time, high-resolution
transmitting system worked very well from liftoff across the optical
horizon to about 320 kilometers distant. At the same time, the MSFC
group was perfecting multiple-camera, single-transmitter equipment
for the Saturn I missions; it became operational just prior to SA-1
in the fall of 1961. The system offered "real-time display and
permanent storage of pictures televised from the vehicle during test
flight." As mounted on SA-6, for example, two camera locations were
utilized. On the ground, a videotape recorder and a kinescope
recorder provided real-time viewing and storage capability. To
identify each picture image, the kinescope recorder system included a
digital key, indicating the camera position and time-of-flight
reference. Within five minutes of a completed flight, high-resolution
individual shots could be available for study.</FONT><B><SUP><FONT
FACE="Geneva"><A HREF="notes.htm#11.5">5</A></FONT></SUP></B></P>

<P><FONT FACE="Geneva">Television was originally selected for use on
rockets because recovery of motion picture film seemed uncertain.
Still, the TV units had limitations because a number of critical
vehicle functions were not compatible with television camera
operations and imagery. For this reason, the Saturn I flights also
incorporated motion picture coverage of test flights.</FONT></P>

<P><FONT FACE="Geneva">A technique to incorporate such coverage was
successfully demonstrated during the Redstone program in 1961 when
inflight photographic instrumentation captured the separation of a
warhead from a Redstone rocket booster. Early in the Saturn
development program, investigators recognized the need for a similar
photo system for visual analysis of phenomena that could not be
simulated during ground testing or acquired through vehicle
telemetry. Plans provided for inflight
[<A NAME="328"></A></FONT><B><FONT FACE="Geneva">328</FONT></B><FONT
FACE="Geneva">] motion picture and television coverage for the first
stage of the SA-1 mission in October 1961 on the basis of the
Redstone camera technology. Lack of time and money prevented use of
such equipment for the first Saturn launches, and effort was
redirected toward the mission of SA-5, the first live, two-stage
Saturn I. Responsibility for the camera became a joint program of
MSFC's Astrionics Laboratory and the Propulsion and Vehicle
Engineering Laboratory. With approval for the project in October
1961, Marshall named Cook Technological Center, a division of the
Cook Electric Company of Chicago, as the major contractor. Cook
Technological Center then proceeded with the development and
manufacture of jettisonable and recoverable camera capsules to be
flown on SA-5, 6, and 7.</FONT></P>

<P><FONT FACE="Geneva">The camera capsules consisted of three
sections: the lens compartment, with camera lens and a quartz viewing
window; the combined camera and its control unit in a separate
compartment; and a recovery compartment, housing descent
stabilization flaps and a paraballoon for descent and flotation, a
radio and light beacon for aid in recovery operations, and more
conventional recovery devices such as sea-marker dye and shark
repellant. The capsules were designed to cope with the stresses of
powered flight, ejection, reentry, impact into the sea, and immersion
in saltwater. Four model "A" capsules were positioned to record
external areas of the Saturn vehicle, facing forward. Four more model
"B" capsules were mounted in an inverted position to record the
phenomena inside designated LOX tanks and around the interstage
between first and second stages. For the "B" models, technicians
linked the cameras with fiberoptic bundles to transmit images from
remote locations and used incandescent lights and strobe systems for
illumination. Engineers preferred to use color film whenever possible
because it provided a better three-dimensional image than the gray
tones of the black and white film. One camera used an extremely fast
and sensitive black and white film to record phenomena inside the
center LOX tank because of the lighting inside the
tank.</FONT><B><SUP><FONT
FACE="Geneva"><A HREF="notes.htm#11.6">6</A></FONT></SUP></B></P>

<P><FONT FACE="Geneva">The launch of SA-5, 29 January 1964, was what
NASA liked to call "a textbook launch." As the first Block II
vehicle, the SA-5 recorded a number of firsts: first S-IV stage to
fly, first guidance and control packages, and first successful stage
separation. The SA-5 was the first Saturn using uprated engines,
marked the first successful recovery of motion picture camera pods,
and was the first orbital Saturn vehicle.</FONT></P>

<P><FONT FACE="Geneva">Although SA-6 got off the launch pad without a
hitch, it caused a moment of concern among mission controllers when
one of the H-1 engines inexplicably shut off prematurely. Unlike
SA-4, this was not part of the programmed flight, but the Saturn
performed beautifully, proving the engine-out capability built into
it by Marshall engineers. With hardly a perturbation, the vehicle
continued its upward climb; stage separation and orbit of the S-IV
upper stage went as planned. Telemetry pinpointed
[<A NAME="329"></A></FONT><B><FONT FACE="Geneva">329</FONT></B><FONT
FACE="Geneva">] the engine problem in the number 8 engine turbopump,
which shut down at 117.3 seconds into the flight. When telemetered
information was analyzed, engineers concluded that the teeth had been
stripped from one of the gears in the turbopump, accounting for the
abrupt failure of the engine. Luckily, Marshall and Rocketdyne
technicians, through previous ground testing of the turbopump, had
already decided that its operating characteristics dictated a
modified design. A change had already been planned to increase the
width of the gear teeth in this particular turbopump model, and the
redesigned flight hardware was to fly on the next vehicle, SA-7.
Consequently, there were no delays in the Block II launch schedule
and, incidentally, no further problems with any of the H-1 engines in
flight.</FONT><B><SUP><FONT
FACE="Geneva"><A HREF="notes.htm#11.7">7</A></FONT></SUP></B></P>

<P><FONT FACE="Geneva">Otherwise, the flight of SA-6 was eminently
successful. The SA-6 was the first to carry a dummy Apollo capsule
into orbit, and it tested the capsule by jettisoning the launch
escape system tower, part of the Apollo spacecraft hardware
development. The performance of the Block II series progressed so
well that the Saturn I boosters were declared fully operational by
NASA officials after the SA-7 flight (18 September 1964), three
launches earlier than expected. The unmanned Apollo spacecraft on
board met guidelines for design and engineering, compatibility of the
spacecraft and launch vehicle, and operation of the launch escape
system. The launch also confirmed the integrity of major critical
areas of the launch vehicle such as the Saturn I propulsion systems,
flight control, guidance, and structural integrity. For SA-7, the
only event that might be considered an anomaly involved the recovery
of the cameras. After stage separation, the jettisoned camera pods
descended by parachute and landed in the sea, downrange of the
expected recovery area. Then Hurricane Gladys blew in and closed the
sector. Seven weeks later, two of the ejected SA-7 camera capsules
washed ashore, encrusted with barnacles, but with the important films
undamaged.</FONT><B><SUP><FONT
FACE="Geneva"><A HREF="notes.htm#11.8">8</A></FONT></SUP></B><FONT
FACE="Geneva"> The last three Saturn I vehicles carried a redesigned
instrument unit with more sophisticated components that did not
require separate, pressurized sections; the result was a lighter and
shorter vehicle with enhanced performance. With a different
environmental control system, the new instrument unit was the
prototype for the Saturn IB and Saturn V vehicles. The most
significant feature that set all three vehicles apart from their
predecessors was the payload&mdash;the unusual, winglike meteoroid
technology satellite known as Pegasus.</FONT><B><SUP><FONT
FACE="Geneva"><A HREF="notes.htm#11.9">9</A></FONT></SUP></B></P>

<H3>Saturns for Science: The Pegasus Project</H3>

<P><FONT FACE="Geneva">Project Pegasus was something of an anomaly in
the Apollo-Saturn program. Responsibility for Pegasus management,
design, manufacture, operation, and analysis of results was charged
to Marshall Space Flight [<A NAME="330"></A></FONT><B><FONT
FACE="Geneva">330</FONT></B><FONT FACE="Geneva">] Center. The
reputation of the Marshall center rested not on satellites, but on
the launch vehicles designed and engineered by the von Braun team.
The Pegasus was also unique because it was the only NASA satellite to
use Saturn boosters. It was especially significant from the
standpoint of designing later versions of the Saturn vehicles. Data
collected by Pegasus would either confirm the ability of existing
designs to operate without danger from meteoroid impact or require
new designs to cope with the dangers of meteoroid collisions. The
Pegasus project was an example of the painstaking scope of the
Apollo-Saturn program research and development to avert any sort of
serious problem. Finally, the project demonstrated several ways in
which the operation contributed to the general store of scientific
knowledge, as well as to the design and operation of boosters,
spacecraft, and associated systems.</FONT><B><SUP><FONT
FACE="Geneva"><A HREF="notes.htm#11.10">10</A></FONT></SUP></B></P>

<P><FONT FACE="Geneva">Meteoric particles striking the Earth travel
at speeds up to 72 kilometers per second. A dust-speck particle,
weighing a mere 0.0085 gram, at such a speed packs the energy of a
.45-caliber pistol fired point blank. Meteoroid phenomena in the
near-Earth space environment commanded serious attention, the more so
because many critical moments of manned Apollo-Saturn missions
occurred in potentially hazardous zones. The Gemini spacecraft
experienced meteoroid impacts many times during a 24-hour period, but
the specks encountered in the lower Gemini orbits were too small to
cause a puncture in the spacecraft skin. Higher orbits for the Apollo
series raised concerns about heavier meteoroid particles. "It is the
stuff of intermediate size that concerns a space-vehicle designer,"
Wernher von Braun emphasized. "Particles of only a few thousandths of
a gram, whizzing at fifteen to twenty miles a second, can penetrate a
spacecraft's wall or a rocket's tank. They constitute a definite
risk." A meteoroid puncture in a gas compartment or propellant tank
could cause a serious leak, and in the case of a highly pressurized
container create an explosive rupture. Particles also created heat at
the moment of impact. With highly volatile propellants aboard, as
well as the oxygen-enriched cabin atmosphere, penetration by a
burning meteoroid would touch off a destructive explosion. Even
without complete penetration, impacts could cause "spalling." The
shock of impact with the skin of a spacecraft could eject fragments
from the skin's interior surface to ricochet inside the vehicle.
These flying fragments raised a serious possibility of danger to a
crew or to vital equipment. The need for information was
clear.</FONT><B><SUP><FONT
FACE="Geneva"><A HREF="notes.htm#11.11">11</A></FONT></SUP></B><FONT
FACE="Geneva"> </FONT></P>

<P><FONT FACE="Geneva">Late in 1962, designers of spacecraft of the
Apollo-Saturn program had very limited knowledge of the abundance of
meteoroids in the vicinity of Earth, where numerous manned flights
were planned and where crucial phases of the lunar missions would
occur. Astronomers could provide information on meteoroids with mass
above 10<SUP>&minus;4</SUP> grams, since they could be sighted optically from
observatories or tracked by radar. Vehicle sensors like those on
</FONT><I><FONT FACE="Geneva">Explorer XVI</FONT></I><FONT
FACE="Geneva"> provided some statistics
[<A NAME="331"></A></FONT><B><FONT FACE="Geneva">331</FONT></B><FONT
FACE="Geneva">] on the abundance of smaller particles, but the lack
of data on the intermediate-sized meteoroids caused persistent
doubts, because information on the intermediate range presented
configuration criteria "of utmost importance for the design of
spacecraft." Pegasus was intended to fill in the gap. As stated in
the official report: "The objective of the Pegasus Meteoroid Project
is the collection of meteoroid penetration data in aluminum panels of
three different thicknesses in near-earth orbits. &hellip;In fact, the
abundance of meteoroids in the mass range 10</FONT><SUP><FONT
FACE="Geneva">&minus;5</FONT></SUP><FONT FACE="Geneva"> to
10</FONT><SUP><FONT FACE="Geneva">&minus;3</FONT></SUP><FONT FACE="Geneva">
will be decisive with respect to the necessary meteoroid protection
for future long-duration manned missions."</FONT><B><SUP><FONT
FACE="Geneva"><A HREF="notes.htm#11.12">12</A></FONT></SUP></B></P>

<P><FONT FACE="Geneva">Attached to the S-IVB second stage, Pegasus
deployed in 60 seconds, extending two wings to a span of 15 meters,
with a width of 4.6 meters and a thickness of about 50 centimeters.
The Pegasus wing mount also supported solar cell panels for powering
the satellite's electronics.</FONT><B><SUP><FONT
FACE="Geneva"><A HREF="notes.htm#11.13">13</A></FONT></SUP></B><FONT
FACE="Geneva"> In full deployment, the Pegasus in flight exposed
about 80 times more experimental surfaces than Explorer meteoroid
detectors exposed. The meteoroid impact sensor was a charged
capacitor with a thin dielectric, a metal foil on one side, and a
sheet of aluminum on the other side. Perforation by a meteoroid
caused a momentary short between the metal plates. The discharge
burned off any conducting bridges between the two metal layers; thus
the capacitor "healed" after each perforation. The shorts, or
discharges, were recorded as hits.</FONT><B><SUP><FONT
FACE="Geneva"><A HREF="notes.htm#11.14">14</A></FONT></SUP></B><FONT
FACE="Geneva"> Special sensors carried by the satellite provided
information on (1) the frequency and size of meteoroids capable of
damaging the spacecraft structure and equipment, and (2) the
direction of the meteoroids as a function of frequency and power of
penetration.</FONT><B><SUP><FONT
FACE="Geneva"><A HREF="notes.htm#11.15">15</A></FONT></SUP></B></P>

<H3>Pegasus Missions</H3>

<P><FONT FACE="Geneva">Planned as part of the qualification program
for the Saturn I rocket, the three Pegasus flights instead assumed
the status of completely operational flights following the success of
SA-7. On 29 December 1964, Pegasus I, the first meteoroid detection
satellite, arrived at Cape Kennedy to join its Saturn I booster,
SA-9.</FONT><B><SUP><FONT
FACE="Geneva"><A HREF="notes.htm#11.16">16</A></FONT></SUP></B><FONT
FACE="Geneva"> The numerical designation of the boosters fell out of
sequence because of variations in their manufacturing. After
designing and building its own first-stage boosters for the Saturn I
program, NASA-MSFC departed from the original concept of work
in-house to rely on industrial contractors. Chrysler Corporation
became the prime contractor for the S-I first stage of the Saturn I,
and Douglas continued to supply the S-IV second stage. In the process
of gaining experience, Chrysler's first Saturn booster, SA-8, moved
less rapidly through manufacturing and test than the last booster
produced by MSFC, SA-9. In retrospect, it seems appropriate that
MSFC's last rocket launched the first Pegasus, MSFC's first
satellite.</FONT><B><SUP><FONT
FACE="Geneva"><A HREF="notes.htm#11.17">17</A></FONT></SUP></B></P>

<P><FONT FACE="Geneva">[<A NAME="332"></A></FONT><B><FONT
FACE="Geneva">332</FONT></B><FONT FACE="Geneva">] To carry the
Pegasus aloft, the S-IV second stage and the instrument unit
underwent some minor modifications. Because heat absorption could
upset the satellite's thermal balance, Douglas supplied the S-IV with
a special coat of paint to reduce the heating factor. New equipment
consisted of an "auxiliary nonpropulsive vent system" to cut down
excessive tumbling and enhance the orbit stabilization. Designers
also incorporated the reworked instrument unit. NASA officials
scheduled the launch of SA-9 for 16 February 1965, and technicians at
Cape Kennedy worked hard to meet their preflight deadlines. With the
Pegasus payload shrouded in the Apollo service module and adapter,
KSC personnel affixed it to the S-IV second stage on 13 January. The
next day, at Launch Complex 37-B, workers finished mating the Apollo
command module to the AS-9 vehicle. In their drive for flawless
operations, NASA and contractor personnel continued to tinker with
the satellite right up to the last minute. On 14 February, only two
days before the launch, technicians from MSFC and Fairchild made
final changes in the meteoroid detection subsystem.</FONT></P>

<P><FONT FACE="Geneva">On 16 February, the Saturn I vehicle SA-9
successfully lifted off from Launch Complex 37-B with NASA's largest
unmanned instrumented satellite to date. It was the first time a
Saturn rocket had been used to loft a scientifically instrumented
payload into space. In a flawless mission, the Saturn I put Pegasus
into orbit, and inserted the command module into a separate orbit
where it would not interfere with scientific measurements. A remotely
controlled television camera, mounted atop the S-IV second stage,
captured a vision of the eerie, silent wings of <I>Pegasus I</I> as they
haltingly deployed.</FONT></P>

<P><FONT FACE="Geneva">Pegasus took 97 minutes to circumnavigate the
Earth. From scattered Moonwatch stations, observers reported the
magnitude of the satellite as zero to seven as it moved through
space.</FONT><B><SUP><FONT
FACE="Geneva"><A HREF="notes.htm#11.18">18</A></FONT></SUP></B><FONT
FACE="Geneva"> When the residual fuel from the S-IV vented, Pegasus
began to tumble, with occasional intense flashes when solar rays
glanced off the large wings. With its moderate orbital inclination
(31&#176; to the equator), the best path for observation in the United
States ran close to Boston and Chicago, but conditions were difficult
because the satellite hovered only a few degrees above the southern
horizon and the extensive slant range made sightings difficult.
However, at the Smithsonian Institution's observatory in South
Africa, visual sightings were easily made. As the sun's light
glittered on the outstretched wings of Pegasus, observers caught
flashes of reflected light that lasted for as long as 35
seconds.</FONT><B><SUP><FONT
FACE="Geneva"><A HREF="notes.htm#11.19">19</A></FONT></SUP></B></P>

<P><FONT FACE="Geneva">Because Pegasus relied on solar cells for
power, NASA spokesmen hoped that the satellite would work at least a
year, but with 55 000 parts in the system, some project officials
were reluctant to predict a full 12-month lifetime, at least for the
first vehicle. In the beginning, everything seemed to be working
well. On its fourth orbit, scientists thought they caught the first
signal of a meteoroid hit, and by the end of
[<A NAME="333"></A></FONT><B><FONT FACE="Geneva">333</FONT></B><FONT
FACE="Geneva">] the first seven days of flight, they were
eagerly anticipating the first full reports read out from the Pegasus
memory banks. In the first two weeks, Pegasus indicated almost a
score of hits by interplanetary objects. By late May, NASA verified
more than 70 meteoroid penetrations. NASA spokesmen unhappily
verified extensive failures in the Pegasus satellite as well, but
MSFC and Fairchild personnel had just enough time to solve these
difficulties before the launches of Pegasus II and
III.</FONT><B><SUP><FONT
FACE="Geneva"><A HREF="notes.htm#11.20">20</A></FONT></SUP></B></P>

<DIV CLASS="figure" ID="fig333a">
<IMG SRC="p333a.jpg">
<P CLASS="caption">A Fairchild technician checks out the extended
Pegasus meteoroid detection surface in March 1964.</P>
</DIV>

<DIV CLASS="figure" ID="fig333b">
<IMG SRC="p333b.jpg">
<P CLASS="caption">An artist's conception of Pegasus in orbit with
meteoroid detector extended.</P>
</DIV>

<P><FONT FACE="Geneva">The second of the meteoroid satellites,
Pegasus II, arrived at KSC on 21 April 1965. The final countdown for
SA-8 began on the afternoon of 24 May. With a scheduled 35-minute
hold, the countdown ticked on without a hitch into the early morning
of the launch, 25 May. The flight of SA-8 marked two especially
notable departures from past experiences in the Saturn program. For
one, the S-I booster was manufactured by Chrysler, and Saturn flew
with a first stage supplied by a contractor for the first time. It
symbolized the end of an era for the von Braun team and the
long-standing arsenal "in-house" philosophy transferred from the
[<A NAME="334"></A></FONT><B><FONT FACE="Geneva">334</FONT></B><FONT
FACE="Geneva">] old ABMA days to the young space program of NASA. For
another, SA-8 blasted off at 2:35 a.m. in the first night launch of a
Saturn rocket. Highlighted against the dark night skies, the winking
lights of the launch tower and the blinding glare of the floodlights
around the base of the launch pad gave the scene an unusual new
fascination. The darkness gave even higher contrast to the fiery
eruption of ignition and the lashing tongues of fire during liftoff.
Always awesome, the thundering roar of the Saturn I's ascent seemed
mightier than ever before, as it seared its way upward through the
dark overcast above the Atlantic. NASA officials timed the launch to
avoid conflict in the communications with <I>Pegasus I</I>, still in orbit.
Both satellites transmitted on the same frequency, and the fiery
night launch of <I>Pegasus II</I> put the second satellite at an angle of
120&#176;, one-third of an orbit apart from the first.</FONT><B><SUP><FONT
FACE="Geneva"><A HREF="notes.htm#11.21">21</A></FONT></SUP></B></P>

<P><FONT FACE="Geneva">The launch illustrated the accuracy of the
propulsion systems and confirmed the reliability of the flight
electronics, which were improved in successive launches of the Saturn
I series. Wernher von Braun praised the flight as "a lesson in
efficiency," and George Mueller, Associate Administrator for Manned
Space Flight, commented that the flight was very significant to
future space flights, with their need for very close timing for
rendezvous missions. <I>Time</I> magazine considered the flight from other
points of view. The magazine approvingly reported the success of the
cluster concept used on the S-I booster and the faultless performance
of the second stage with its six RL-10 engines: "The smooth success
of last week's launch suggests that LH</FONT><SUB><FONT
FACE="Geneva">2</FONT></SUB><FONT FACE="Geneva"> has at last become a
routine fuel." The editors acknowledged the need for more information
on meteoroid hazards in space flight but found the greatest
significance in the launch itself. "Far more encouraging for space
exploration," said <I>Time</I>, "was the smoothness with which the
many-tiered rocket was dispatched into the sky." So often a rocket
vehicle spent weeks or months on the pad with delays, but no setbacks
occurred in the launch of SA-8, "which left its pad as routinely as
an ocean liner leaving its pier."</FONT><B><SUP><FONT
FACE="Geneva"><A HREF="notes.htm#11.22">22</A></FONT></SUP></B><FONT
FACE="Geneva"> The second Pegasus satellite began returning data in
short order. Within one day after launch, it indicated two meteoroid
penetrations. Modifications on <I>Pegasus II</I> included successful
refinement of the detector electronics and a handful of minor
readjustments. The second Pegasus experienced some troubles during
its mission, primarily with the analog and digital telemetry
channels. Technicians finally smoothed out the digital failure, and
even though the analog transmissions continued intermittently, they
worked well enough to rate the mission a success. Tracing the source
of trouble, workers finally decided it originated in a thunderstorm
during preparation of the spacecraft on the pad, because the wettest
section contained the circuit failure.</FONT><B><SUP><FONT
FACE="Geneva"><A HREF="notes.htm#11.23">23</A></FONT></SUP></B></P>

<P><FONT FACE="Geneva">On 21 June 1965, the Apollo command module and
associated hardware arrived at KSC for the launch of the last
meteoroid detection satellite, Pegasus III. With planned
modifications for Launch Complex [<A NAME="335"></A></FONT><B><FONT
FACE="Geneva">335</FONT></B><FONT FACE="Geneva">] 37-B to service the
uprated Saturn IB launch vehicle, NASA officials decided to move the
flight of SA-10 ahead to 30 July to avoid delays in both the launch
and the modifications of the launch pad. Technicians ran a series of
checks to verify panel deployment and compatibility of systems, then
joined Pegasus III to the instrument unit of the SA-10 vehicle. On 27
July 1965, the KSC launch crew ran an uneventful and successful
countdown demonstration test for SA-10, the last Saturn I. By 29
July, the final phase of the launch countdown was under way and
proceeded with no technical holds to liftoff on the next day. The
SA-10 vehicle performed flawlessly, inserting the command module and
<I>Pegasus III</I> into the planned orbital trajectory. On the basis of data
from all three meteoroid detection satellites, NASA spokesmen
announced in December that the Apollo-Saturn structure would be
adequate to withstand destructive penetration by meteoroids during
space missions. The Pegasus project was
successful.</FONT><B><SUP><FONT
FACE="Geneva"><A HREF="notes.htm#11.24">24</A></FONT></SUP></B></P>

<P><FONT FACE="Geneva">The information gathered by the Pegasus trio
included much more than variations in theoretical meteoroid
penetration data. In his capacity as Director of the Space Sciences
Laboratory, Ernst Stuhlinger praised the secondary results, which
returned scientific data valuable to the design and engineering of
future spacecraft, as well as knowledge of specific scientific
nature. "It sometimes occurs that an experiment, planned for one
specific objective, provides observational results far beyond the
single-purpose mission for which it was originally conceived," he
said. "Project Pegasus, which has the primary objective of measuring
the near-Earth environment, is an example in case." For the benefit
of spacecraft designers, the 65 000 hours accumulated in all three
missions provided significant and valuable data on meteoroids, the
gyroscopic motion and orbital characteristics of rigid bodies in
space, lifetimes of electronic components in the space environment,
and thermal control systems and the degrading effects of space on
thermal control coatings. For physicists, the Pegasus missions
provided additional knowledge about the radiation environment of
space, the Van Allen belts, and other phenomena.</FONT><B><SUP><FONT
FACE="Geneva"><A HREF="notes.htm#11.25">25</A></FONT></SUP></B></P>

<P><FONT FACE="Geneva">The last of the meteoroid detection
satellites, <I>Pegasus III</I>, carried a captivating experiment, one of the
first intended to be left in space, to be personally retrieved by an
astronaut at some future date. Eight large detector segments were
removed from the Pegasus wings, replaced with "dummy" panels and 48
temporary coupons, cut from samples of the detector surfaces. The
coupons, in turn, carried 352 items of test materials and thermal
samples, some of them in use, others considered as candidates for
future application. Examples of the test items included aluminum skin
specimens, ranging from sandblasted and anodized surfaces to pieces
covered with luminescent paint and gold plate. The launch of
</FONT><I><FONT FACE="Geneva">Pegasus III</FONT></I><FONT
FACE="Geneva"> put it into an orbit of 530 kilometers. After 12
months, NASA planners expected the orbit of </FONT><I><FONT
FACE="Geneva">Pegasus III</FONT></I><FONT FACE="Geneva"> to decay
some, [<A NAME="336"></A></FONT><B><FONT
FACE="Geneva">336</FONT></B><FONT FACE="Geneva">] putting it in
position for a potential rendezvous with a Gemini spacecraft.
Theoretically, one of the Gemini astronauts could emerge from the
Gemini capsule, maneuver himself to the Pegasus wings, recover a
selected group of test specimens, and return to the spacecraft. With
the return of the astronaut's armful of samples to Earth, scientists
could not only make direct studies of the effect of meteoroid impacts
on metals in interplanetary space but also examine specimens of
meteoroids taken directly from the space environment. Unfortunately,
the experiment was never possible during Gemini, and the final
Pegasus reentered the atmosphere on 4 August 1969. Its destruction
during reentry brought an untimely end to an intriguing
experiment.</FONT><B><SUP><FONT
FACE="Geneva"><A HREF="notes.htm#11.26">26</A></FONT></SUP></B></P>

<H3>Saturn I in Retrospect</H3>

<P><FONT FACE="Geneva">In terms of rocket development, the series of
Saturn I launches was remarkably successful. Most rocket programs had
severe teething troubles early in the game; up to two or three dozen
test shots and loss rates of 50 percent were not out of the ordinary.
True, the Saturn I used engines and tanks extrapolated from earlier
programs, but uprating the H-1 engine had brought difficulties, and a
cluster of this magnitude was untried. Moreover, the later Saturn
missions introduced a sizable new LH</FONT><SUB><FONT
FACE="Geneva">2</FONT></SUB><FONT FACE="Geneva"> upper stage, powered
by a cluster of six RL-10 engines.</FONT></P>

<P><FONT FACE="Geneva">For all this, there seems to have been
persistent criticism of the Saturn I series of launches. Basically,
it appeared to be a multimillion-dollar launch vehicle program with
no significant missions or payloads. Even before the launch of SA-2
in the spring of 1962, NASA had announced the Saturn V. It was this
vehicle, not Saturn I, that had the mission and payload that counted:
a lunar voyage with a payload equipped to land men on the moon and
get them back again. As a preliminary to Saturn V missions, plans
were already in progress for the Saturn IB, which would test a Saturn
V third stage in orbit and begin qualification of crucial hardware
such as the command module and lunar module.</FONT></P>

<P><FONT FACE="Geneva">The Saturn I, as one NASA historian has
written, was a "booster almost overtaken by events." A number of
individuals, within NASA as well as on the outside, felt that Project
Highwater and, to a lesser extent, Project Pegasus were makeshift
operations to give Saturn I something to do and to placate critics
who complained that the Saturn was contributing little to science.
There is probably some truth in these allegations. Highwater in
particular seems to have been an impromptu operation, revealing
nothing new. Although NASA literature solemnly referred to scientific
aspects, von Braun called Highwater a "bonus experiment," and noted
that the water was already aboard Saturn I stages as
ballast.</FONT><B><SUP><FONT
FACE="Geneva"><A HREF="notes.htm#11.27">27</A></FONT></SUP></B></P>

<P><FONT FACE="Geneva">With hindsight, the apparently superfluous
Saturn I launches still contributed to the Saturn program,
underscoring the innate conservatism
[<A NAME="337"></A></FONT><B><FONT FACE="Geneva">337</FONT></B><FONT
FACE="Geneva">] of Marshall Space Flight Center. Aware of potential
early failures in a launch series, MSFC evidently planned for
several, but to make the series as successful as possible, Marshall
also went into each launch with vehicles tested and retested to the
point where the possibility of failure was virtually eliminated.
Marshall's own thoroughness made the remarkable string of 10
successful launches seem unnecessarily redundant. In any case, the
launches verified many concepts for systems and subsystems applied to
later Apollo-Saturn missions, provided valuable experience in the
operation of LH</FONT><SUB><FONT FACE="Geneva">2</FONT></SUB><FONT
FACE="Geneva"> stages, demonstrated the validity of the cluster
concept, and tested early versions of Saturn guidance and control.
Payloads for the Saturn I launches may not have been as dramatic as
those for other vehicles, but Saturn I missions, overall, were
nevertheless beneficial.</FONT></P>

<P><FONT FACE="Geneva">In a strict sense, the series of Pegasus
launches was not very earthshaking. None of the three satellites
promoted any fantastic new discoveries; no dramatic design changes
occurred in either the Saturn launch vehicles or the Apollo
spacecraft as a result of unexpected information about meteoroid
penetration. The value of the Pegasus involved a positive, rather
than a negative, reading of the test results. The satellites
confirmed basic estimates about meteoroid frequency and penetration
in the operational environment of the Apollo-Saturn vehicles. This
confirmation provided a firm base of knowledge to proceed with basic
designs already in the works. In fact, it was good that the Pegasus
series did not turn up significantly different data, which would have
entailed costly redesign and additional time and research into
meteoroid phenomena as related to boosters and spacecraft. Instead,
the effect was to add to the growing confidence of Apollo-Saturn
designs already in process and to permit NASA to plunge ahead toward
the goal of landing man on the moon within the decade. It would have
been easy to dismiss what was, in fact, a successful developmental
phase in the overall Apollo-Saturn program.</FONT><B><SUP><FONT
FACE="Geneva"><A HREF="notes.htm#11.28">28</A></FONT></SUP></B></P>

<P><FONT FACE="Geneva">In terms of subsequent programs, the legacy of
Pegasus included significant contributions in the development of
thermal coatings used on many major satellites, as well as on the
Apollo spacecraft. The Pegasus also had a significant impact on the
development of the communications satellite (comsat) project, because
the results indicated that the comsat satellites would indeed have a
profitable lifetime in orbit, the probability being high that they
would survive or escape damage from meteoroids. Wernher von Braun was
emphatic on this point: "I would say the Pegasus data have really
become the main criteria of spacecraft design, ever since Pegasus,
for all manned and unmanned spacecraft."</FONT><B><SUP><FONT
FACE="Geneva"><A HREF="notes.htm#11.29">29</A></FONT></SUP></B></P>

<H3>Junior Partner to Apollo: Saturn IB</H3>

<P><FONT FACE="Geneva">The Saturn IB represented significant advances
toward the hardware and techniques to be used in lunar landings. S-IB
first stages included a [<A NAME="338"></A></FONT><B><FONT
FACE="Geneva">338</FONT></B><FONT FACE="Geneva">] number of
modifications to increase the overall vehicle performance, as
compared with the S-I series. The aerodynamic fins were further
modified, and changes in fabrication techniques saved considerable
weight (see </FONT><FONT FACE="Geneva"><A HREF="ch3.htm">chapter
3</A></FONT><FONT FACE="Geneva">). The eight H-1 engines were uprated
from 836 000 to 890 000 newtons (188 000 to 200 000 pounds) of thrust
each. Most importantly, the Saturn IB missions provided an
opportunity to flight-test the first Saturn V hardware. The S-IVB
upper stage with its single J-2 engine was nearly identical to the
upper stage carried on the Saturn V, and the same was true of the
instrument unit (see </FONT><FONT
FACE="Geneva"><A HREF="ch8.htm">chapter 8</A></FONT><FONT
FACE="Geneva">).</FONT><B><SUP><FONT
FACE="Geneva"><A HREF="notes.htm#11.30">30</A></FONT></SUP></B></P>

<P><FONT FACE="Geneva">Saturn IB missions began with the unmanned
launch of AS-201 from KSC Launch Complex 34 on 26 February 1966. With
both stages live, the vehicle made a successful 32-minute suborbital
flight, reaching an altitude of over 480 kilometers with impact into
the south Atlantic about 320 kilometers from Ascension Island.</FONT>
</P>

<P><FONT FACE="Geneva">The primary tests concerned separation of the
spacecraft, followed by the command module's reentry into Earth's
atmosphere. The maneuver successfully demonstrated that the command
module's heat shield could withstand the intense temperatures created
by atmospheric friction during reentry. The first Saturn IB
experienced relatively few problems in flight, although the mission
was nearly canceled during countdown. Bad weather delayed the launch
date for three days, and on the day of the liftoff, launch officials
postponed the firing command for three hours while technicians did
some trouble-shooting on several last-minute technical problems. The
most serious difficulty involved the gaseous nitrogen purge system
that cleaned out the engines and the related machinery prior to
launch. At T&minus;4 seconds, the gaseous nitrogen pressure limits had
dropped below the red-line level and an automatic cutoff sequence was
started. After resetting the equipment and starting the countdown
once more, at T&minus;5 minutes engineers perceived the problem again and
requested a hold. Engineers estimated that it would possibly take two
hours of work to recheck and reset all the equipment. Reluctantly,
the recommendation was made to scrub the launch. Still searching for
options, a group of launch crew engineers suggested a different test
of the system to assess other alternatives, and stage engineers
agreed; so the countdown was restarted at T&minus;15 with the gaseous
nitrogen pressures reset at different levels. The countdown and
launch were finally completed successfully.</FONT><B><SUP><FONT
FACE="Geneva"><A HREF="notes.htm#11.31">31</A></FONT></SUP></B></P>

<P><FONT FACE="Geneva">Saturn IB missions carried inflight visual
instrumentation perfected during the Saturn I missions. Only two
movie cameras were used, however, and a ribbon parachute was added to
the capsules to slow their descent even more, because some capsule
damage had occurred on the SA-6 mission. Typically, the cameras were
located atop the first stage to record stage separation and ignition
of the S-IVB second stage. On the AS-201 flight neither of the
parachutes worked properly, and the Air Force recovery team found
only one capsule. On the other hand, the
[<A NAME="339"></A></FONT><B><FONT FACE="Geneva">339</FONT></B><FONT
FACE="Geneva">] guidance and control system performed as expected,
telemetry was good, and no structural problems were discerned. The
propellant utilization system worked as designed: the LOX and
LH</FONT><SUB><FONT FACE="Geneva">2</FONT></SUB><FONT FACE="Geneva">
were depleted simultaneously. All things considered, the two-stage
Saturn IB vehicle achieved a notable inaugural
flight.</FONT><B><SUP><FONT
FACE="Geneva"><A HREF="notes.htm#11.32">32</A></FONT></SUP></B></P>

<P><FONT FACE="Geneva">The second launch of the Saturn IB series, on
5 July 1966, carried an out-of-sequence number designation, AS-203.
Originally scheduled for the second launch in the series, AS-202
became third in line to gain additional time for checkout of its
Apollo spacecraft payload. NASA made the announcement in April,
explaining that the AS-203 mission primarily involved launch vehicle
development. Mission objectives for the second Saturn IB launch
concentrated on the orbital characteristics and operation of the
S-IVB second stage, so the vehicle had a simple aerodynamic nose cone
in place of the Apollo spacecraft. Launch officials considered the
second stage itself, with 10 metric tons of liquid hydrogen aboard,
as the payload. Testing was scheduled to gain further information
about liquid hydrogen in the orbital environment and about procedures
for reignition of the S-IVB in orbit, a requirement for Saturn V
missions in the future. The reignition sequence was not to be live
but simulated with the S-IVB and J-2 engine systems. In an attempt to
telescope development of the stage and engine operations, last-minute
consideration was given to an actual restart of the J-2 engine. A
number of people within Marshall Space Flight Center, however,
opposed restarting the J-2 because that would unduly complicate the
developmental flight. In a letter to Major General Samuel C.
Phillips, Eberhard Rees estimated that a complete restart sequence
would require an additional 1800 kilograms of liquid oxygen and 1400
kilograms of other equipment and provisions and would compromise the
main test goals of the behavior of liquid hydrogen in the orbital
environment as well as other test procedures. "Douglas and MSFC are
confident that a successful AS-203 mission, as presently defined,"
said Rees, "should establish whether or not successful restarts can
be accomplished on Saturn V missions."</FONT><B><SUP><FONT
FACE="Geneva"><A HREF="notes.htm#11.33">33</A></FONT></SUP></B></P>

<P><FONT FACE="Geneva">For reignition under weightless conditions,
fuel and oxidizer had to be settled in the bottoms of the propellant
tanks. Engineers hoped to achieve this through the use of the
hydrogen continuous vent system. The venting gas imparted thrust
which pushed the propellants to the bottom of the tanks. This thrust
could be augmented by occasionally opening the liquid oxygen tank
propulsive vent valve. To study the stability of the liquid hydrogen
in orbit and to check settling of the liquid hydrogen at the bottom
of the tanks, the S-IVB carried a pair of TV cameras mounted inside
the tank. Prior to launch, a checkout of the TV system uncovered
trouble in one of the cameras. After a hold of almost two hours, NASA
engineers decided not to postpone the launch any longer and the
vehicle lifted off with only one of the cameras expected to work.
Fortunately, the remaining camera functioned well, and the
[<A NAME="340"></A></FONT><B><FONT FACE="Geneva">340</FONT></B><FONT
FACE="Geneva">] images verified the hopes for proper propellant
behavior during venting and for settling of the propellants prior to
reignition. Motion picture color coverage of stage separation,
recovered from the ocean in one of the camera capsules, was also of
high quality and showed the desired performance.</FONT></P>

<P><FONT FACE="Geneva">Following the satisfactory TV coverage of the
behavior of liquid hydrogen under weightless conditions and a
simulated restart of the J-2, technicians proceeded with the plan to
break up the S-IVB stage in orbit. This rather dramatic procedure was
intended to verify ground tests that had been carried out on
structural test models at Douglas facilities on the West Coast.
Investigators from Douglas and MSFC wanted to establish design limits
and the point of structural failure for the S-IVB common bulkhead
when pressure differential developed in the propellant tanks. Ground
tests were one thing; the orbital environment of space was another.
Breakup occurred near the start of the fifth orbit when the common
bulkhead failed and the stage disintegrated. The results confirmed
the Douglas ground experiments; the S-IVB stage could withstand
tankage pressure differentials over three times that expected for
normal mission operations.</FONT><B><SUP><FONT
FACE="Geneva"><A HREF="notes.htm#11.34">34</A></FONT></SUP></B></P>

<P><FONT FACE="Geneva">AS-202, launched on 25 August 1966, returned
to the suborbital mission profile because the primary purpose was to
test the heat shield on the command module (CM). Extensive holds,
taking up three days, had been caused by problems with the spacecraft
and ground telemetry. With the problems finally resolved, the AS-202
vehicle lifted off in a flawless launch. The S-IVB successfully
tested its ullage rockets and ignited as planned despite some minor
valve malfunctions in the recirculation system of the J-2. Separation
of the S-IVB and the CM caused oscillatory motions of the S-IVB,
which could have made for tricky maneuvers for CM docking with the
lunar module (LM) in manned missions, but the S-IVB auxiliary
propulsion system brought the stage back under control. In accordance
with the planned profile, the CM made a "skipping" reentry to raise
the heat loads and subject the heat shield to maximum punishment.
Recovery of the scorched CM occurred near Wake Island in the Pacific
Ocean.</FONT></P>

<P><FONT FACE="Geneva">The success of the first three Saturn-IB
missions heightened expectations for the first manned launch,
scheduled for 21 February 1967 as AS-204. The three-man crew included
Virgil I. Grissom, Edward H. White II, and Roger B. Chaffee. During a
checkout of the complete vehicle on the launch pad at KSC's Launch
Complex 34 on 27 January, a flash fire erupted inside the CM. Trapped
inside, the three astronauts died.</FONT><B><SUP><FONT
FACE="Geneva"><A HREF="notes.htm#11.35">35</A></FONT></SUP></B></P>

<P><FONT FACE="Geneva">The exhaustive investigation of the fire and
extensive reworking of the CMs postponed any manned launch until NASA
officials cleared the CM for manned flight. Saturn IB schedules were
suspended for nearly a year, and the launch vehicle that finally bore
the designation AS-204 carried an LM as the payload, not the Apollo
CM. The missions of AS-201 and [<A NAME="341"></A></FONT><B><FONT
FACE="Geneva">341</FONT></B><FONT FACE="Geneva">] AS-202 with Apollo
spacecraft aboard had been unofficially known as Apollo 1, and Apollo
2 missions (AS-203 carried only the aerodynamic nose cone). In the
spring of 1967, NASA's Associate Administrator for Manned Space
Flight, Dr. George E. Mueller, announced that the mission originally
scheduled for Grissom, White, and Chaffee would be known as Apollo 1
and said that the first Saturn V launch, scheduled for November 1967,
would be known as Apollo 4. The eventual launch of AS-204 became
known as the Apollo 5 mission (no missions or flights were ever
designated Apollo 2 and 3).</FONT><B><SUP><FONT
FACE="Geneva"><A HREF="notes.htm#11.36">36</A></FONT></SUP></B></P>

<P><FONT FACE="Geneva">As <I>Apollo 5</I>, the original AS-204 vehicle
lifted off from Launch Complex 37 at KSC on 22 January 1968 in an
unmanned test of the lunar module in Earth orbit. The LM was enclosed
in a spacecraft-lunar-module adapter and topped by an aerodynamic
nose cone in place of the Apollo command and service modules (CSM).
Evaluation of the LM included ignition of the descent and ascent
stages and LM staging and structures. Engineers also intended to
conduct an S-IVB propellant dumping experiment in orbit, following
separation of the stage from the LM. Dumping was considered necessary
to make the S-IVB safe before docking of the CSM with the
S-IVB-attached LM.</FONT></P>

<P><FONT FACE="Geneva">Some months prior to the AS-204 mission, NASA
planners realized that the vehicle was going to be sitting stacked on
pad 37 for a considerable period of time awaiting the arrival of the
LM. NASA took advantage of the opportunity to monitor the conditions
of the launch vehicle over a long period of time, as it stood on the
pad exposed to the elements on the Florida coast. On 7 April 1967,
the first stage had been erected; the second stage and the instrument
unit were added in the next four days. Marshall and contractor
personnel devised a detailed set of criteria for periodic inspections
of the vehicle starting that same month. No components had to be
replaced because of corrosion; advance planning had paid off. The
vehicle was under constant nitrogen purges to protect the engine
compartment and other equipment areas from the salty atmosphere. The
vehicle propellant tanks were also kept under pressure with dry
nitrogen. These procedures were maintained during a kind of musical
chairs operation as the LM and its associated hardware were moved in
and out, off and on, for several weeks. After arrival of its ascent
and descent engines and their mating, they had to be taken apart in
August to repair leaks in the ascent engine. Then the two stages were
mated again until September when a new leak required demating.
Several items of LM hardware had to be shipped back to the contractor
for additional work. The ascent and descent engines of the LM were
put together again in October, and tests were run until November when
the spacecraft was taken to the pad and mechanically mated with the
booster. The flight readiness tests were not accomplished with the
total vehicle until late in December with the LM in position, nearly
nine months after the launch vehicle had been put in place on Launch
Complex 37.</FONT></P>

<DIV CLASS="figure" ID="fig342">
<IMG SRC="p342.jpg">
<P CLASS="caption">A cutaway drawing of the Saturn IB launch
vehicle.</P>
</DIV>

<P><FONT FACE="Geneva">[<A NAME="343"></A></FONT><B><FONT
FACE="Geneva">343</FONT></B><FONT FACE="Geneva">] The successful
mission of AS-204 in January 1968 was therefore very gratifying to
the launch vehicle crews as well as to the LM crews. Both the first
and the second stages performed well, and a new
liquid-hydrogen-recirculation-chilldown control valve on the S-IVB
worked without a hitch, eliminating a potential problem uncovered on
the AS-202 mission. The guidance and telemetry systems met
requirements, the panels protecting the LM deployed, and the LM
separated from the S-IVB with no trouble. During the S-IVB liquid
oxygen dump and liquid-hydrogen dump experiments, the exhausting of
propellants through the J-2 engine caused minor attitude variations
in the stage, but these were corrected by the thrust vector control
system and the auxiliary propulsion system modules. On the morning of
23 January 1968, the S-IVB stage disintegrated during reentry. AS-204
once more set the stage for the first manned launch in the
Apollo-Saturn program: AS-205, known as Apollo 7.</FONT><B><SUP><FONT
FACE="Geneva"><A HREF="notes.htm#11.37">37</A></FONT></SUP></B></P>

<DIV CLASS="figure" ID="fig343a">
<IMG SRC="p343a.jpg">
<P CLASS="caption">The first S-IB rises successfully from KSC's Launch
Complex 34 on 26 February 1966.</P>
</DIV>

<DIV CLASS="figure" ID="fig343b">
<IMG SRC="p343b.jpg">
<P CLASS="caption">The first manned Saturn IB, Apollo 7, is shown on
the launch pad at night, poised for takeoff the next day, 11 October
1968.</P>
</DIV>

<P><FONT FACE="Geneva">Launched on 11 October 1968 from KSC Launch
Complex 34, the <I>Apollo 7</I> had a crew made up of Walter M. Schirra,
Jr., Donn F. Eisele, and [<A NAME="344"></A></FONT><B><FONT
FACE="Geneva">344</FONT></B><FONT FACE="Geneva">] R. Walter
Cunningham. Primary objectives for the mission pertained to the CSM,
crew performance, manned mission support facilities for the CSM, and
CSM rendezvous techniques. With three astronauts aboard and the
necessary provisions to sustain them in orbital flight, the launch of
AS-205 marked again an increase in payload capability. Much of this
increase came from the reduction of measurement instrumentation from
the prior Saturn launches. AS-204 had required 1225 measurements; 720
sufficed in AS-205. The <I>Apollo 7</I> spacecraft also was the product of
extensive redesign since the disastrous fire the year before. It
featured a quick-opening one-piece hatch, an extensive substitution
of materials to reduce flammability, and a modification of the cabin
atmosphere for testing and prelaunch operations. Even though primary
attention centered on the manned aspects of the mission, NASA and
Rocketdyne personnel were closely watching the augmented spark
igniter lines for the J-2, which had been modified after they failed
during the <I>Apollo 6</I> mission on 4 April 1968 (see </FONT><FONT
FACE="Geneva"><A HREF="ch12.htm">chapter 12</A></FONT><FONT
FACE="Geneva">).</FONT></P>

<P><FONT FACE="Geneva">The ascent of both Saturn IB stages went like
clockwork. During the boost phase of the S-IC stage, Schirra
routinely reported an instrument readout of the pitch program, and
noted, "She[&rsquo;s] running&mdash;it's getting a little noisy now." Then
Schirra called out the sequence of inboard and outboard shutdown of
the H-1 engines, followed by confirmation of S-IVB ignition on cue at
programmed thrust levels. In between comments from Schirra that the
ride from the S-IVB was "a little bumpy," flight controllers in
Houston also caught Schirra's enthusiastic remark, "She's riding like
a dream," and a voice from the spacecraft that "the window view is
sensational."</FONT><B><SUP><FONT
FACE="Geneva"><A HREF="notes.htm#11.38">38</A></FONT></SUP></B><FONT
FACE="Geneva"> After more than one hour in orbit, the instrument unit
initiated the automatic "safing" sequence, which included the
propellant dumping operation. Separation of the CSM from the spent
S-IVB stage took place on schedule, and the astronaut crew turned the
CSM around for the simulated docking maneuver (the AS-205 did not
actually carry an LM). As part of the simulated LM rendezvous
exercise, the CSM was maneuvered to a station-keeping position near
the spent S-IVB stage as it tumbled through space. On 18 October,
seven days after liftoff, the S-IVB reentered over the Indian Ocean.
The three astronauts completed 63 orbits before successful reentry
and splashed down into the Atlantic on 22 October, where they were
picked up by teams from the recovery ship <I>Essex</I>. The <I>Apollo 7</I> mission
achieved all primary mission objectives, and the last of the Saturn
IB flights was over. NASA intended the AS-201 through AS-205 flights
to qualify the Apollo spacecraft, and the requirements had been met.
The Saturn IB first stages had also performed as expected, but more
importantly the S-IVB upper stage and the instrument unit for the
Saturn V were successfully qualified in orbit.</FONT><B><SUP><FONT
FACE="Geneva"><A HREF="notes.htm#11.39">39</A></FONT></SUP></B><FONT
FACE="Geneva"> In less than a year, the space agency expected to land
men on the moon. That mission required the giant Saturn V.</FONT>
</P>

<H3>Summary</H3>

<P><FONT FACE="Geneva">[<A NAME="345"></A></FONT><B><FONT
FACE="Geneva">345</FONT></B><FONT FACE="Geneva">] With the exception
of the S-IVB, every stage of the Saturn launch vehicles depended on
clustered engines. The feasibility of large, high-thrust engine
clusters was demonstrated by the first successful launch of the
Saturn I and verified in one mission after another. Later Saturn I
flights (the Block II series) proved the feasibility of using liquid
hydrogen fuels in Saturn upper stages. The Saturn I series also
provided the opportunity to perfect visual instrumentation systems
and to try out evolving concepts of guidance and control as well as
hardware and software tagged for the manned lunar landing program.
Even though the Highwater experiments contributed little to
astronautical science, the Pegasus flights yielded pertinent
information that confirmed booster and spacecraft designs under way
and accumulated scientific data that influenced the design and
operations of later manned and unmanned spacecraft.</FONT></P>

<P><FONT FACE="Geneva">Introduction of the Saturn IB afforded NASA
the opportunity to flight-test important elements of Apollo-Saturn
flight hardware. This included the S-IVB upper stage, the instrument
unit, the command and service modules, and the lunar module. During
the Saturn IB missions, operations planned for the Saturn V were
given a trial run, including orbital coast and restart of the S-IVB
and stage separation of the S-IVB and lunar module. The orbital
operations and restart of the J-2 engine subjected the instrument
unit to the kind of sequencing critical for future lunar missions,
and advanced telemetry and visual instrumentation yielded knowledge
of the behavior of cryogenic propellants (particularly liquid
hydrogen) in orbit.</FONT></P>

<P><FONT FACE="Geneva">Finally, the Saturn IB powered the first
manned Apollo mission, <I>Apollo 7</I>. This manned, Earth-orbital mission
cleared an important hurdle before the towering Saturn V lifted a
similar payload and steered a course for the moon.</FONT></P>

<P><CENTER><FONT FACE="Geneva">
<HR>
</FONT><FONT FACE="Geneva"><A HREF="part6.htm"><IMG SRC="previous.gif"
ALT="previous" WIDTH=40 HEIGHT=40 X-SAS-UseImageWidth
X-SAS-UseImageHeight BORDER=2 ALIGN=bottom></A></FONT><FONT
FACE="Geneva"><A HREF="contents.htm"><IMG SRC="index.gif" ALT="index"
WIDTH=40 HEIGHT=40 X-SAS-UseImageWidth X-SAS-UseImageHeight BORDER=2
ALIGN=bottom></A></FONT><FONT FACE="Geneva"><A HREF="ch12.htm"><IMG
SRC="next.gif" ALT="next" WIDTH=40 HEIGHT=40 X-SAS-UseImageWidth
X-SAS-UseImageHeight BORDER=2 ALIGN=bottom></A></FONT></CENTER>
</BODY>
</HTML>