This repository has been archived by the owner on Jul 17, 2020. It is now read-only.
-
Notifications
You must be signed in to change notification settings - Fork 2
/
ch3-5.html
306 lines (268 loc) · 15.3 KB
/
ch3-5.html
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
<!DOCTYPE HTML>
<HTML>
<HEAD>
<title>Chariots For Apollo, ch3-5</title>
<meta http-equiv=Content-Type content="text/html; charset=UTF-8">
</head>
<BODY BGCOLOR="#FFFFFF">
<h2>Analysis of LOR</h2>
<p>
Most of the early criticism of the lunar rendezvous scheme stemmed from
a concern for overall mission safety. In the minds of many, rendezvous -
finding and docking with a target - would be a difficult task even in
the vicinity of the earth. This concern was the underlying reason for
the trend toward larger and larger Saturns (C-2 through C-5) to lessen
the number of maneuvers required. After all, von Braun had once
suggested that as many as 15 launchings of the smaller launch vehicles
might be needed for one mission. During earth-orbital operations, the
crew could return to the ground if they failed to meet their target
vehicle or had other troubles. In lunar orbit, where the crew would be
days away from home, a missed rendezvous spelled death for the
astronauts and raised the specter of an orbital coffin circling the
moon, perhaps forever. And all this talk about rendezvous came at a time
when NASA had only a modicum of space flight experience of any kind. It
is not surprising, therefore, that Houbolt had trouble swinging others
away from their advocacy of direct flight or earth-orbit rendezvous.<p>
Fears for crew safety and lack of experience were not the only factors;
the Langley approach was criticized on another score - one as damning as
the danger of a missed rendezvous. One of the principal attractions of
Houbolt's mode was the weight reduction it promised; but he and his
colleagues, in trying to sell the mode, had oversold this aspect. Many
who listened to the Langley team's proposals simply did not believe the
weight figures cited, especially that given for the lunar landing
vehicle. In the lunar mission studies at Vought Astronautics, Dolan and
his team had given much thought to designing the hardware, including a
landing vehicle. Their weight calculations for a two-man lunar landing
module were much higher than those proposed by the Langley engineers.
Vought's study projected a 12,000-kilogram vehicle, most of which was
fuel. Empty, the lander would weigh only 1,300 kilograms.<a href =
"#source37"><b>37</b></a><p>
But, until late 1961, no one in NASA except Langley had really looked
very hard at lunar landing vehicles. Using theoretical analyses and
simulations, the rendezvous team at the Virginia center had studied
hardware, "software" (procedures and operational techniques),
flight trajectories, landing and takeoff maneuvers, and spacecraft
systems (life support, propulsion, and navigation and guidance).<a href
= "#source38"><b>38</b></a> The studies formed a solid foundation for
technical design concepts for a landing craft.
<p align=center>
<img src = "images/c074a.jpg" width=608 height=404 ALT="LaRC lander concept">
<p>
<cite>This sketch is an artist's concept of a small lunar lander during
descent to the surface of the moon, as proposed by Langley Research
Center employees in October 1961.</cite>
<p>
<hr>
<p>
Langley's brochure for the Golovin Committee described landers of varied
sizes and payload capabilities. There were illustrations and data on a
"shoestring" vehicle, one man for 2 to 4 hours on the moon; an
"economy" model, two men and a 24-hour stay time; and a
"plush" module, two men for a 7-day visit. Weight estimates
for the three craft, without fuel, were 580, 1,010, and 1,790 kilograms,
respectively. Arthur Vogeley pictured the shoestring version as a solo
astronaut perched atop an open rocket platform with landing legs. To
expect Gilruth's designers to accept such a "Buck Rogers space
scooter" would seem somewhat optimistic.<a href =
"#source39"><b>39</b></a><p>
<p align=center>
<img src = "images/c074b.gif" width=506 height=389 ALT="Lander for advanced Mercury s/c">
<p>
<cite>These engineering drawings were made by Harry C. Shoaf (Space Task
Group Engineering Division) 15 November 1961 of a proposed lunar lander
to be used with an advanced version of the Mercury spacecraft.</cite>
<p>
<hr>
<p>
The same sort of minimal design features extended to subsystems, and
structural weights further reflected Langley's drive toward simplicity.
In February 1961, at NASA's intercenter rendezvous conference, Lindsay
J. Lina and Vogeley had described the most rudimentary navigation and
guidance equipment: a plumb bob, an optical sight, and a clock. This
three-component system was feasible, they said, "only because
maximum advantage is taken of the human pilot's capabilities." Even
some of those on the Langley team criticized this kind of thinking; John
Eggleston, for one, labeled it impractical.<a href =
"#source40"><b>40</b></a><p>
Despite Houbolt's frustration, his missionary work had stimulated
interest outside Langley. Within the Office of Manned Space Flight,
George Low, Director of Spacecraft and Flight Missions, commented that
"the 'bug' approach may yet be the best way of getting to the moon
and back."<a href = "#source41"><b>41</b></a> And Houbolt had
finally struck a responsive chord when giving his sales talk to the
Space Task Group in August. At this briefing, James Chamberlin, Chief of
the Engineering Division, had been very attentive and had requested
copies of the Langley documents. All during the year, Chamberlin and his
team had been working on a study of putting two men in space in an
enlarged Mercury capsule (which later emerged as Project Gemini).<a href
= "#source42"><b>42</b></a> Although this successor to Mercury had been
conceived as earth-orbital and long-duration, Chamberlin thought it
might fly to the moon, as well. Seamans recalled that Chamberlin
"was trying to develop something that was almost competitive with
the Apollo itself." Chamberlin did, indeed, offer an alternative to
Apollo. He and several of his colleagues proposed using the two-man
craft and lunar rendezvous in conjunction with a one-man lunar lander,
which in many respects resembled the small vehicles studied by
Langley.<a href = "#source43"><b>43</b></a><p>
Although Chamberlin could get approval only for the earth-orbital part
of his plan, one of his principal objectives - rendezvous - was highly
significant. It marked the beginning of the first important shift in the
Apollo mode. Gilruth and his engineers began to perceive advantages they
had not previously appreciated.<p>
Growing interest in lunar-orbit rendezvous stemmed partially from
disenchantment with direct flight. The Space Task Group had become
increasingly apprehensive about landing on the moon in one piece and
with enough fuel left to get back to earth. The command section it had
under contract was designed as an earth-orbital, circumlunar, and
reentry vehicle. It could not fly down to the surface of the moon. Lunar
rendezvous, which called for a separate craft designed for landing,
became more inviting.<a href = "#source44"><b>44</b></a><p>
Gilruth's engineers had worked on several designs for a braking rocket
for lunar descent. In a working paper released in April 1961, Apollo
planners had tried to size a propulsion system for landing, even though
no booster had yet been chosen to get it to the moon. Two methods for
landing were explored. The first was to back the vehicle in vertically,
using rockets to slow, then stop, the spacecraft, setting it down on its
deployed legs. The second technique was to fly the spacecraft in
horizontally, like an aircraft. In this case, the legs would be deployed
from the side of the craft instead of from the bottom.<a href =
"#source45"><b>45</b></a><p>
In the summer of 1961, when the command module contract was being
advertised, Max Faget described some of the problems he anticipated with
the landing itself. All other phases of the mission could be analyzed
with a fair degree of certainty, he said, but the actual touchdown could
not, since there was no real information on the lunar surface. Exhaust
from rocket engines on loose rocks and dust might damage the spacecraft,
interfere with radar, and obstruct the pilot's vision. Faget said the
final hovering and landing maneuvers must be controlled by the crew to
ensure landing on the most desirable spot. The Apollo development plan,
in its many revisions, merely said that the lunar landing module would
be used for braking, hovering, and touchdown, as well as a base for
launching the command ship from the moon.<a href =
"#source46"><b>46</b></a><p>
About the time of the contract award, Abe Silverstein left NASA
Headquarters to become Director of Lewis Research Center.<a href =
"#source47"><b>47</b></a> It had become increasingly apparent that
Apollo would probably use one rendezvous scheme or another, and he was
among the staunchest advocates of big booster power and direct flight.
Concurrently with Silverstein's return to Cleveland, Lewis was assigned
to develop the lunar landing stage. Gilruth and Faget did not like this
division of labor, as it added a complex management setup to the
technical difficulties of matching spacecraft and landing stage.<p>
Faget proposed a different propulsion module from the one previously
envisioned for the descent to the lunar surface. He suggested taking the
legs off the landing module and making it into just a braking stage,
which he called a "lunar crasher." Once this stage had eased
the spacecraft down near the surface, it would be discarded to crash
elsewhere before the Apollo touched down. The Apollo spacecraft would
then consist of the command center and two propulsion modules, one to
complete the landing and the other to boost the command module from the
surface. Since the crasher's only job was to slow the spacecraft, it was
not part of the vehicle's integral systems, which decreased the
technical interfaces required and minimized Lewis' role in the hardware
portion of Apollo. Faget based his proposal on some sound technical
reasoning. The crasher engines would be pressure-fed, no pumps would be
needed, and the vehicle could be controlled by turning the engines off
and on as long as the propellant lasted. Pump-fed engines, on the other
hand, depended on complex interactions to vary the thrust. Faget and
Gilruth liked the pressure-fed system, and so did Silverstein.<a href =
"#source48"><b>48</b></a><p>
Although relations with Lewis were easier after the adoption of the
crasher, the Houston engineers were still worried about the complexities
of an actual landing. As Faget later said, "We had all sorts of
little ideas about hanging porches on the command module, and periscopes
and TV's and other things, but the business of eyeballing that thing
down to the moon didn't really have a satisfactory answer. . . . The
best thing about the [lunar rendezvous concept] was that it allowed us
to build a separate vehicle for landing."<a href =
"#source49"><b>49</b></a> Caldwell Johnson, one of the chief
contributors to the Apollo command module design, had much the same
reaction. He said, "We continued to pursue the landing with a big
propulsion module and the whole command and service module for a long,
long time, until it finally became apparent that this wasn't going to
work."<a href = "#source50"><b>50</b></a><p>
By the end of 1961, the newly named Manned Spacecraft Center had
virtually swung over to the lunar-orbit rendezvous idea. Gilruth, Faget,
and the other Apollo planners conceded that this approach had drawbacks:
a successful rendezvous with the mother craft after the bug left the
lunar surface was an absolute necessity, and only two of the three crew
members would be able to land on the moon. But the stage had been set
for an intensive campaign to sell the von Braun team on this mode. At
Headquarters, Director of Manned Space Flight Holmes wanted the two
manned space flight centers to agree on a single route - he did not
expect to get this consensus easily.<a href = "#source51"><b>51</b></a>
<p>
<hr>
<p>
<a name = "source37"><b>37</b>.</a> Richard B. Canright to James D. Bramlet et
al., no subj., 27 Nov. 1961, with enc., Canright, "The Intermediate
Vehicle," 22 Nov. 1961; James F. Chalmers, minutes of LLVPG general
meeting, 28 Aug. 1961; O'Neal memo, 30 Jan. 1961; Clark enc.,
"Manned Modular Multi-Purpose Space Vehicle."<p>
<a name = "source38"><b>38</b>.</a> [Houbolt et al.], "Manned Lunar
Landing through Lunar-Orbit Rendezvous"; Eggleston interview.<p>
<a name = "source39"><b>39</b>.</a> [Houbolt et al.], "Manned Lunar
Landing through Lunar-Orbit Rendezvous"; Bird and Houbolt
interviews.<p>
<a name = "source40"><b>40</b>.</a> Lindsay J. Lina and Arthur W. Vogeley,
"Preliminary Study of a Piloted Rendezvous Operation from the Lunar
Surface to an Orbiting Space Vehicle," Langley Research Center, 21
Feb. 1961; Houbolt and Eggleston interviews.<p>
<a name = "source41"><b>41</b>.</a> George M. Low to Dir., NASA OMSF,
"Comments on John Houbolt's Letter to Dr. Seamans," 5 Dec.
1961.<p>
<a name = "source42"><b>42</b>.</a> Purser to Gilruth, "Log for Week of
August 28, 1961," 5 Sept. 1961; Bird, "Short History," p.
4; Houbolt interview; STG, "Preliminary Project Development Plan
for an Advanced Manned Spacecraft Program Utilizing the Mark II Two Man
Spacecraft," 14 Aug. 1961.<p>
<a name = "source43"><b>43</b>.</a> Seamans interview, 26 May 1966; Harry C.
Shoaf, interview, Cocoa Beach, Fla., 10 Oct. 1968.<p>
<a name = "source44"><b>44</b>.</a> Seamans interview, 26 May 1966; Purser to
Howard Margolis, 15 Dec. 1970. See also John D. Hodge, John W. Williams,
and Walter J. Kapryan, "Design for Operations," in
"NASA-Industry Apollo Technical Conference," pt. 2, pp.
41-56.<p>
<a name = "source45"><b>45</b>.</a> H. K[urt] Strass, "A Lunar Landing
Concept," in Strass, ed., "Project Apollo Space Task Group
Study Report, February 15, 1961," NASA Project Apollo working paper
no. 1015, 21 April 1961, pp. 166-74; Senate Committee on Aeronautical
and Space Sciences, <cite>NASA Authorization for Fiscal Year 1961:
Hearings on H.R. 6874,</cite> 87th Cong., 1st sess., 1961, pp. 71-75.<p>
<a name = "source46"><b>46</b>.</a> Maxime A. Faget, "Lunar Landing
Considerations," in "NASA-Industry Apollo Technical
Conference," pt. 1, pp. 89-97; STG, "Project Apollo Spacecraft
Development, Statement of Work, Phase A," 28 July 1961; STG,
"Preliminary Project Development Plan for Apollo Spacecraft,"
9 Aug. 1964, pp. 7-10; MSC, "Project Apollo Spacecraft Development
Statement of Work," 27 Nov. 1961, pp. 78-81.<p>
<a name = "source47"><b>47</b>.</a> Robert L. Rosholt, <cite>An Administrative
History of NASA, 1958–1963,</cite> NASA SP-4101 (Washington, 1966), p.
222.<p>
<a name = "source48"><b>48</b>.</a> Seamans, interview, Washington, 11 July
1969; Faget interview, 15 Dec. 1969; Faget, interview, comments on draft
edition of this volume, Houston, 22 Nov. 1976.<p>
<a name = "source49"><b>49</b>.</a> Faget interview, 15 Dec. 1969.<p>
<a name = "source50"><b>50</b>.</a> Johnson, interview, Houston, 9 Dec.
1966.<p>
<a name = "source51"><b>51</b>.</a> Purser letter, 15 Dec. 1970.
<P>
<HR>
<P>
<CENTER><A HREF="ch3-4.html">
<IMG SRC="previous.gif" ALIGN="left"
ALT="Previous Page">
</A>
<A HREF="ch3-6.html">
<IMG SRC="next.gif" ALIGN="right"
ALT="Next Page">
</A>
<A HREF="contents.html">
<IMG SRC="index.gif" ALIGN="middle"
ALT="Table of Contents"></A>
</CENTER><BR>
<HR>
<P>
</BODY>
<!--ADA TEAM 2001-->
</HTML>