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DESTINATION MOON: A History of the
Lunar Orbiter Program
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- CHAPTER VIII: LUNAR ORBITER
MISSION OBJECTIVES AND APOLLO REQUIREMENTS
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- Developing Mission
Designs
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- [183] While Bellcomm
was advising OMSF, the Langley Lunar Orbiter Project Office
carefully studied and compared the proposed missions that Bellcomm
had developed (i.e., in the Lloyd-Fudali report) with the one
developed by Boeing. Thomas Young of the Langley LOPO informed
Norman L. Crabill on May 7 of the conclusions pertaining to the
reliability of each proposed mission. His memorandum stressed the
differences in reliability in the studies performed by Bellcomm
and Boeing. The Bellcomm mission required 4.5 days longer to
accomplish than did that of Boeing, but the variation in resulting
data was minimal.10
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- Young's LOPO mission planning study group
continued to analyze Lunar Orbiter capabilities and concluded in a
report to Crabill on June 14 that Apollo and Surveyor requirements
permitted variable Lunar Orbiter missions, ranging from a
concentrated to a distributed photographic mission, depending upon
primary requirements for the two programs. For photographic
missions with sites distributed within the Apollo zone, a set of
trajectories could be defined that were generally independent of
the exact locations of the sites. They could be planned by placing
mild [184] restrictions on the latitude range of the sites.
Thus, for Missions I, II, and III (with prime sites in the Apollo
zone), trajectories could be defined without consideration of the
exact site locations. Mission II sites were to be selected from
the review of the results of secondary sites of Mission I. and
Mission III sites were selected from all results of the first two
missions.11 However, the Langley Project Office considered the
establishment of mission objectives a prerequisite to further
mission planning.12
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- On Friday, June 25, representatives from
OSSA, OMSF, the Langley Lunar Orbiter Project Office, the Manned
Space Flight Center, the Jet Propulsion Laboratory, and Bellcomm
held the initial coordination meeting to establish a preliminary
plan for utilizing Lunar Orbiter's mission capabilities with the
first Lunar Orbiter mission, the first Surveyor mission, and with
Apollo mission requirements. During the meeting it was agreed that
the Lunar Orbiter could best aid Surveyor by screening sites and
defining targets which had a high probability of being smooth. The
[185]
representatives from the Apollo Systems Engineering Office stated
that Lunar Orbiter could photograph a landed Surveyor spacecraft
from an altitude of 46 kilometers with I-meter resolution because
of the Surveyor's shadow at a prescribed Sun angle and the high
albedo of the spacecraft. Lunar Orbiter had originally been
targeted to screen Surveyor sites. After a Surveyor had
successfully landed, the Orbiter was to overfly it and photograph
it through the 610 mm high-resolution camera lens. The increased
capabilities of the Lunar Orbiter photo subsystem now allowed it
to combine screening and overfly tasks in the high-resolution
mode.13
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- The Apollo Systems Engineering Office and
the Manned Space Flight Center preferred that Lunar Orbiter fly a
distributed mission; this offered a sampling technique better able
to find an area suitable for an Apollo landing, to define suitable
areas for further coverage on later Orbiter flights, and to
increase the flexibility of the Apollo launch window by finding
suitable sites spread across the Apollo zone of interest. Both the
Manned Space Flight Center and Bellcomm recommended that Lunar
Orbiter photograph the Ranger
VIII impact point located in the
Apollo zone because possibly it could serve as a future
[186]
Apollo orbit anchor point.14
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- The June 25 Langley meeting provided the
Lunar Orbiter Project Office with information concerning mission
objectives from the Apollo and the Surveyor Program Offices. This
assisted Langley in its mission planning activities, and it, in
turn, was better able to guide the Boeing Company in its
work.15 Moreover, the meeting produced the basis for
efficient coordination between the NASA offices requiring Lunar
Orbiter data and enabled the Lunar Orbiter Program to develop
preliminary mission plans.16
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- From July 13 to 15 a preliminary mission
definition meeting for Lunar Orbiter convened at Langley. The men
present17 defined preliminary mission types on the basis of
decisions arising out of the June 25 meeting at Langley. These
mission types depended upon three basic flight objectives: 1)
gathering significant topographic information of the Moon's
surface for selection of Surveyor, and Apollo [187] sites; 2)
providing selenodetic data on the size, shape, and gravitational
properties of the Moon necessary for determining orbit lifetime of
a Lunar Orbiter sufficiently long to allow adequate time for
readout; and 3) providing measurements of micrometeoroid and
radiation flux in the lunar environment.18
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- By the end of July the Lunar Orbiter
Program Office in Washington had the results of the Langley LOPO
and Bellcomm preliminary mission studies. Four mission types had
been formulated on the basis of requirements and recommendations
from Apollo, Surveyor, and Lunar Orbiter Program Offices. Briefly
summarized they were:
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- Type I -Site sampling, a distributed
mission allowing eleven single passes over different terrains
(i.e., highlands, maria, rilles).
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- Type II -wide-area coverage for Surveyor
of only three separate sites.
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- Type III -Surveyor location mission to
pinpoint landed Surveyor at one-meter resolution.
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- Type IV -a combination million for more
sophisticated work later in the program.19
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- A joint OSSA/OMSF Site Survey Meeting was
held at NASA Headquarters on August 4 to review the status of the
Surveyor, Lunar Orbiter, and Apollo Programs and to discuss
[188]
preliminary mission planning for Lunar Orbiter and selection of
Surveyor landing sites. Clifford H. Nelson, Lunar Orbiter Project
Manager, summarized the status of the Lunar Orbiter Program and
pointed out that the program expected to meet its original launch
schedule but that slips in subsystems, especially the photographic
subsystem, had necessitated further compression of the testing
schedule in order to hold the launch schedule.20
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- After Nelson's report and the Apollo
status report., Norman L. Crabill presented the preliminary
planning for the first two Lunar Orbiter mission types. He
outlined the ground rules for the Type I mission:
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- Ground Rules
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- 1) Photograph two sites of each
smooth-looking-terrain class up to a total of eleven sites
within the Apollo area of interest.
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- 2) Photograph Ranger VIII and
any landed Surveyors.
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- 3) Photograph each site using a single
pass with sixteen contiguous I-meter-resolution frames per
pass.
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- 4) Read out up to four frames between
passes.
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- 5) Define mission for the Boeing
Company by the fall of 1965.
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- And for the Type II mission:
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- Objectives
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- 1) Topography mapping for possible
Surveyor sites.
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- 2) [189]
High-precision selenodetic data.
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- 3) Lunar environmental data.
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- Ground Rules
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- 1) Photograph three sites spread
30° of longitude apart.
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- 2) Use four passes per site.
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- 3) Use sixteen high-resolution
contiguous frames per pass.21
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- At the August 4 meeting Lee R. Scherer
proposed the establishment of a Lunar Photographic Analysis
Steering Group which would act as a sounding board for suggestions
and requests from the various programs involved in lunar
exploration. It would also establish priorities and serve as
coordinator for NASA-wide activities related to obtaining
photographic data of the Moon. The group could coordinate such
activities as control of Earth-based lunar mapping, direction and
planning in the analysis of Lunar Orbiter data, monitoring of
pertinent work for other government agencies, planning with the
OSSA planetology group, handling agreements for data processing
priorities, and coordinating Apollo needs with other requirements.
No final action was taken on Scherer's proposal at the meeting,
but it stimulated discussion on these aspects of mission planning
and data utilization.22
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