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BYEMAN

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To: DDR&E

From: AD/ST

18 April 1968

Problem:

To ac uaint you with the background and current status of Mr.

per, "Mapping from Satellite Photography."

Background: 

Last November, lammumniwilikh i e f Scientist,

Autometric Operation, Raytheon Company was invited to present a

paper to the American Society of Photogrammetry and the George

Washington Universit as part of the latter's Distinguished Lecture

Program. elected "Mapping from Satellite Photography"

as his topic, a su ject which flows naturally from his Autometric

activity, where he works on portions of the National Reconnaissance

Program (his clearances are SI, TK).

He processed his paper, at the last minute, through DIAMC

(mapping and charting), which believed that, with a few changes, the

paper was presentable.

During discussions on the subject, appeared quite

hostile to security review (or control).. was as a result of this

experience, as well as ex riences with certain I aepers and

charters, tha NRO. and IA, instituted a procedure calling for all cleared DOD persons to send any

papers they prepared on earth-sensing to DIAXX, prior to presentation. publication, or regular (white) submission to ASD/ PA (see

Tab A).

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-TOP-SECRET-- BYEMAN

Canna syslan

•

On January 24, 1968, the Raytheon Company sent a paper, "Mapping from Satellite Photography, " to ASD/PA, requesting clearance

for presentation at the Canadian Institute of Surveying at Edmonton,

Canada on January 31.

Reviewing a copy of the paper, I was struck with the many

security problems it raised (see Tab B). ad employed

a very positive tone throughout; his references to resonant altitudes,

80 n. m. as a practical perigee, the feasibility of stellar photography,

Mark 5 recovery vehicles, the deboosting procedure, and the use of

thin base film could only have come from someone thoroughly acquainted with the NRP.

This January version of per was very similar to the

November version, but did extend a little farther into forbidden areas.

I advised DIA that this paper could not be given. I asked if the DIA and

the NRO Staff would be embarrassed over denying clearance in January

to a paper that had cleared in November. Colonel Worthman reviewed

my copy of the paper and said he shared my concern. Our decision was

passed to Autometrics.

On January 30, we received a call from the local Autometrics

office and were advised b • a security administrator, that

Raytheon had instructs to become ill and return home from

Canada. Agallink also informed me that (1) the National Academy

of Sciences had the offending speech in galleys for inclusion in a forthcoming manual of the American Society of Photogrammetry but that

Autometrics was withdrawing it promptly from publication, and (2) the

National Academy of Sciences had booked 'for a series of

speaking engagements as a Visiting Lecturer on this same subject.

Could Autometrics representatives meet with someone to discuss this

problem?

On February 13, DIA sponsored a meeting to examine the extent

of problem. Colonel Worthman and I joined this meeting

and explains , in detail, the national polic background for the security

actions we had taken. We analyzed `\ paper, pointing out

.1.1,1 .41

BYEMAN -TOP-SECRET- INCIVINIO 'WA SOWNalle Palit.A•f.,044111,

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TOP-SEGRET-- BYEMAN COMM MINI

to him that it is virtually impossible for a cleared person to write on

satellite reconnaissance without giving something away. He, and persons like him, were very close to a situation where one can be a member

of the team and keep silent or not make the team and be vocal.

imillmiand the Autometrics re resentatives who accompanied ,

him were respectful and cooperative. 'raised two follow-on

problems:

I. An American Society of Photogrammetry request that he present a paper on lunar mapping during its March convention.

2. An International Society of Photogrammetry reqdest that he

organize a presentation on NASA Photogrammetric Space Program to

be given at Lucerne, Switzerland next summer.

I promisedallialihat we would give him prompt replies on

both uestions. I also told him that I would ask the NRO's101111.

mapping ex rt to meet with him to search for a good

tec nice area in which could prepare s eeches and papers

in the future. It seemed important to us to gi safety

valve of some kind so that he could continue to be active in journals

and symposia.

The answer to a safety valve fo

photogrammetric geodesy of the moon.

terms of reference in this regard:

turned out to be the

orked out

Size and density of control nets to be based explicitly on lunar

requirements.

Cameras for lunar mapping to be frame cameras of 6-, 12-

and 24-inch focal lengths. There would be no mention of panoramic

or strip cameras.

3. References to orientation of terrain cameras and/or the

vehicle by the use of stellar cameras would be based on data collected

from ESSA BC-4 cameras.

1•1110•11 •

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4. Discussions of moon-mapping at scales such as 1 to 50,000

or better would reference aircraft program capabilities already

known to the scientific public.

Based on these guidelines, 'agreed that he could prepare a good paper for the March meeting of the American Society of

Photogrammetry and did so (see Tab C).

Regarding his Lucerne meetingAllnikarranged to have

Dr. Loman or Dr. McNair (both unwitting) prepare a paper on the

uses of GEMINI photography, emphasizing geology and map revision.

In summary, our arrangements were such thano

longer walked the borderline of NRP disclosure. He wou , owever,

11111 til t

be able to continue to give excellent papers in his field of interest,

following our guidelines.

Present Status:

Several weeks ago, Mr. Heinz Gruner, President of the American

Society of Photogrammetry, sent a letter to Dr. William Pecora,

oriel• a

Director, U. S Geological Survey. protesting the restrictions placed

on per (see Tab D). Dr. Pecora sent the letter to

Dr. Don ornig, asking for advice in answering it. Dr. Hornig, in

turn, sent it to Dr. Flax, asking for "the wording of a letter that Dr.

Pecora might send as a reply to Mr. Gruner"(see Tab E). 1003

Since the entire action was taken by OSD, specifically in the

DDR&E and DIA arenas, I have advised Don Steininger that we would

reply directly to Mr. Gruner. He has cleared this proposed action

with Dr. Pecora.

Implementation:

Tab F is a proposed reply to. Mr. Gruner. Essentially, we tell

him that OSD took the action, that such actions are routine with our

contractors, that they are taken in the national interest, and that

lawless BYEMAN CORM St 11,111

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-TOP-'SECRET- BYEMAN OW1401115115

IIIIIIIIIII‘ now has an excellent new paper which Mr. Gruner can use

to rep ace the previous version.

Recommendation:

That you sign Tab F.

BYEMAN -TOP-SECREF

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Mar= FRO:: SATELLTTE PHOTOGRAPHY

(Revised for publication, December 1967)

AMER:GAX SOCZTY OF PHOTOORAMMETRY

National Science Foundation

Visiting Scientist Program
• •

MAPPING FROM SA:ELLITS PHOTOGRAFHT

Within the memory of easy men mow alive, maps were mods by the

ground surveyor lugging his theodolite, plass table, sod elided* across

the plains and up the mountaina• la the years following World War II,

the ground surveyor was largely replaced by the cartographic aerial camera

and the photOgremeetrie plotting instrument. This imsawation produced

quantum jumps in production, geometric accuracy, and content of topographic asps.

Where Do We Stand Todaw 

At the present UM* fully sleety percent of all new map compilation

are produced photograsinerrically• Yet in spite of mere than half a century

of effort, the mapping task is woefully incomplete. Around the world only

about half of the land area is cowered by principil arcs of triangulation,

and much less than half by first sad lower order triangulation. The status

of compiled maps is indicated in this table.

WORLD IUDIVAXD U. S. MAP COURAGE

World Nap Coverage

Quality Seal: Scale Medium Scale Large Scale lemerhe

1:600,000 1:75,400

LUG to

1:75,000

and

Smaller 1:600,000. Larger

Adequate ISZ 52 Principally

Require Revision 332 SZ SZ 0. S. and Europe

:nadecuote 70.2 40Z 10X

Nonexistent 40X SOX nn•••••n

V. Si Nap Coverage.

A4equate 10GX 962 642

Inadequate 42 • M•••MO

Sonexistent 32* ••••••n

Data compiled by Arty Nap Service, and exclude Antarctica
Of primary concern is the fact that the rats of obsoleicensi of

existing maps nearly equals the production of sew maps, so that with -

present techniques the jib will never be completed. Furthermore, the map

production cycle is About three years from photography to printing so that

the new mop is three years sot el date as she day it is published.

Geographers would like to see the Billion scale sap of the

world (11/00 completed. They state that most 1:250,000 maps are deficient

In content. They need large scale 1:25,000 maps of all populated areas.

Geologists, 1111110AMITS, and ether map users need similar scales. Kousver, of

first priority to all is the rapid retrials:: of existing maps. Some sort of

Parkinson's Low operates to make maps most difficult to compile and most

rapidly obsolete is precisely those areas where the, are seeded most

urgently. Naps of large urban arose should be.recompiled annually. The

currant cycle in the Gaited St.W.48 is five to tea years.

The Gstint Phototraoty 

The use of the artificial satellite as a camera carrying vehicle

is expected to provide a jump is nappies capability comparable to that'

which the airplane made over the pound surveyor. The Gemini Photography

was made with as ordinary band held Masselbled camera. On edisloas S and

7 photographs were made of the Cape Kennedy launch area. These two pictures,

never intended for cartographic purposes, were used to revise the plant-

:et:1c detail on the existing army Map Service 1:250,000 map of the area.

:n another application of the Genial photography, the C. S.

Geological Survey compilede mosaic of most of Peru, parts of !envie

and Chile. Control points were selected from existing 1:1,000,000 maps

and identifies on the individual Gemini Frames. These were than rectified

and photograph tilts of as much as 40• were removed. Despite 20,000 feet

of topographic relief a reasonable match cos obtained, and the resultant

photomap gives a view of the osustry never seen before.

. •
•

But these are baby steps. What could be done. with a system

actually designed with cartographic objectives in mind?

Map Recuirements 

Before exploring the potentialLties of space cartographic

systems, it would be well to recall the requirements for producing maps.

A topographic nap contains three kinds of information. The

first is content, i.e., the details which are represented on the map.

Content is provided by photographic resolution and scale, or more directly

by ground resolution.' In this area the exact capability of space photography remains to be demonstrated. For a variety of reasons it seems

probable that the ground resolution obtainable with a given lens-film

resolution will be higher from space than a simple gee:metric extrapolation

from the scale of airplane photography would indicate. A useful criterion

to apply is that the photography can be enlarged until its resolution is

equivalent to between 10 and 20 line pairs per millimeter. This will

present all the information which the human, eye can extract without enlarging the map scale by magnification. Not all map information is

obtainable directly from photography, regardless of its scale or ground

resolution. :rata such as political boundaries, place names, and detail

obscured by vegetation must be compiled on the ground or from other sources.

:t is estimated that if the suggested resolution criterion is applied,

about 80 percent of the total map information can be extracted from"the

photographs.

The second kind of information is the position of the objects

shown on the map. For some applications the relative positions of all

ob!ects will be sufficient, but it is usually necessary and always

desirable to attempt to specify all positions with respect to some well

defined coordinate system, either 'local or national. Map positions are

indicated by the reference ;reticule: longitude and latitude, state

coordinates, or military grid lines.
The third kind of information is elevation - generally shown

by contour lines above a reference surface - usually mean sea level.

In the United States, criteria for position and elevation on

maps exist in the National Map Accuracy Standards. Applied to photogrammetric mapping,these standards, and the higher resolution criterion

defined above, result in the values given in the following table. A fixed

contour interval does not necessarily go with a given map scale. An

interval fine enough to depict the terrain will be chosen.

MAP ACCURACY REQUI RENE=

Map Std. Error Ground • Contour Std. Error

Scale Position Resolution Interval Elevation

1,0C11,000 300 meters 50 meters 500 meters 150 meters

250,000 75 12.5 100 30

100,000 30 5.5 50 15

50,000 15 2.5 25 8

25,000 7.5 1.3 .10 3

The numbers in this table represent the objectives against which

a space cartographic system should be evaluated.

Orbita: Constraints on Photap.ra:.hic Coveraee 

It is immediately clear that if full coverage of the Earth is

recuired, a near polar orbit is necessary. Of course, if napping is to

be restricted to specific areas, orbits of lower inclination can be

employed. ' But for elementary discussion only near polar orbits will be

considered.

An orbit is approximately fixed in inertial space and Earth rotates

beneath it. At precz1cal altitudes the satellite period is approximately

: 1/2 hours and in that tine the Earth will rotate some 22 1/2. of. longitude,

i.e., about 2500 km. Since no reasonable camera can cover 2500 km on a
single photograph it is necessary to arrange the mission such that consecutive days will fill in the gaps. There exist so called "resonant" altitudes

at 4, 145, and 303 nautical miles, at which each day's coverage would

exactly duplicate the preceding day and the gaps would never be filled.

In order to perform the gap filling function efficiently, It Is necessary

to make compromises in selecting orbital altitude, eccentricity, and

inclination. Although orbits as low as 80 n.m. can be flown, for several

reasons including spacecraft lifetime, an altitude of about 125 n.m. (232 km)

is desirable.

As illustrated in Figure 1, the other critical parameter is the

width of the ground track covered by the camera. This dimension, divided

into the 2500 km between consecutive orbital passes will determine the

minimum number of days in orbit which would be _required to obtain complete

coverage in the gaps. Quite obviously, if the spacecraft can remain in

orbit for more than this minimum time, it will get more than one look at

each spot. This is clearly desirable in view or the cloud cover which may

be expected.

Resa:ution rind Mr., SC410 

The relationship between camera focal length, orbital altitude,

lens-film resolution, and ground resolution is shown in Figure 2. For

a wide anple cartographic camera, current technology limits average lensfilm resolution to approximately 50 lines per millimeter. Thus, as indicated

by line 1, a standard 6 inch camera, flying at 125 n.m. altitude, with this

resolution, would produce a ground resolution of about 27 meters. Comparing

this number against • the resolution requirements stated earlier, it is evident

that such a camera system would p rovide map content adequate for maps at

about 1:500,000 scale. :n order to obtain the 12 to 15 meter resolution

required for maps Zt ::250,000, a frame camera of 12 inch focal length,

indicated by line 2, would be required.

To produce adequate resolution for the larger map scales with •

wide angle camera systems restricted to 50 lines per millimeter would

-5-
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41 hi' Figure 1 - Coverage of Satellite Photography
Figure 2 - Relation Between System Parameters
require cameras of extremely long focal lengths and unreasonable film

formats. For this reason consideration is given to panoramic cameras

which are capable of producing resolution between 100 and 200 lines per

millimeter. Such cameras, however, have inherently poor geometric fidelity,

and cannot satisfy the requirements for position and elevation accuracy.

Line 3 on the chart shows that a 24 inch panoramic camera at 150 lines per

millimeter could produce about 2 meters ground resolution - adequate for

standard maps at scale 1:50,000, or, by relaxing the resolution criterion

slightly, for maps at scale 1:25,000. Panoramic cameras require sophisticated

and expensive photogrammotric instrumentation not generally available. For

this reason an eventual operational system for producing or revising large

scale maps may well go to longer focal length, narrow angle, frame cameras,

which might attain IGO lines.per millimeter and a corresponding ground

resolution of 3.5 meters. The ground width covered by such a camera would

necessarily be small. As a consequence the satellite would require a very

long lifetime in order to be able to photograph any desired area with

vertical pictures, or else the camera would have to take oblique pictures

to the side of the ground track.

Geometric MQD Accuracy 

At an elementary level, the position and elevation accuracy

obtainable by photogrammetric procedures is:

and

where

dP •

dii •

•

dx n

dP n 7 dx

E 

Gil • — — dx

f

ground position accuracy

ground elevation accuracy

flight altitude

distance between exposures making up a stereo pair

accuracy of Law measurement
•

Stereo base 3 is obtained by exposing the photographs at time

intervals such that some part of the ground area covered by one photograph

is also covered by a following photograph. With the 6 inch standard

camera, consecutive photographs overlap by 60 percent and B n 0.6 W. In

order to obtain adequate 3 with a 12 inch camera, a film format of 9 x 14.5

4hoi•• to pr* small with • • inah aimanalan perpendicular to the flight

direction. Consecutive photographs will overlap by 67 percent, and

a stereo model will be composed of alternate photographs. This arrangement

will provide an effective 3. 0 0.8 H. Because 24 inch cameras have a

narrow field of view, they cannot achieve adequate B by overlapping vertical photographs. Consequently two cameras will be required in a

"twin convergent" configuration with one camera directed forward along

the flight line and the other directed aft. If the angle off the vertical

is 20° for each camera, the effective base in each stereo model will be

B n 0.7 H.

The current level of accuracy in recovering the position of_

an image on a single photograph is approximately dx 0.005 ma. This

is representative of the relative accuracy which can be obtained in a

single stereo model. However, as every photogrammetrist knows, a stereo

model must be scaled, positioned, and levelled before geometric map

data can be extracted from it. Conventionally this is done by reference

to ground control, and errors . accumulate alarmingly as one departs from

the control.

In this regard, satellite photography will have an enormous

advantage over aircraft photography. The satellite orbit is mathematically

predictable, and if the time of each camera exposure is recorded precisely,

the position of the Ciimera can be accurately determined. Furthermore, as

shown in Figure 3, a photograph of the star field can be made in synchronism

with each terrain photograph, and measurement of the stellar photograph

will provide the absolute angular orientation of the camera to a few seconds

of arc. These data are equivalent to having ground control in every stereo

-9-
b - TINE BETWEEN

EXPOSURES 4 0.5 MS

N - EPHEMERIS

RECONSTRUCTION

• a x - ATTITUDE

RECORDING =RA

Figure 3 - Exterior Orientation of Satellite Photography
modal. The consequence is that errors will not accumulate to the same

extent when the photographs are triangulated in a strip or block, and a

value of dx n 0.020 mm is expected to be a reasonable estimate of the

absolute accuracy with which image positions can be recovered.

If the appropriate values of H. f, a and dx are applied for the

three camera systems under considoyation, the values listed in the following

table are obtained.

GEOMETRIC MA? ACCURACY OBTAINABLE

6 inch

camera

12 inch

camera

24 inch

camera

Altitude N (125 n.m.) 232 km. 232 km. 232 km.

Focal length f 152 mm. 305 mm. 610 mm.

Relative accuracy position d? 7.7 m 3.8 m 1.9 m

elevation dB 12.8 m 4.8 a 2.7 m

Absolute accuracy position dP 30.7 m 15.2 m 7.6 m

elevation dH 51.3 m •19.0 m 10.9 a'

If these geometric numbers and the resolution numbers previously

discussed are compared with the requirements for mapping at different

scales, the capabilities of the three camera systems can be summarised.

CAMERA SYSTEM CAPABILITY

6 inch 12 inch 24 inch

Relative Mapping camera camera camera

Content for map scale 500,000 250,000 25,000 to 50.000

Position accuracy for map scale 25,000 25,000 10,000

. •

Elevation accuracy for contour interval 50 m 15 m 10 n

Absolute Mapping

Content for sapsclae 500,000 250,000 25.000 to 50,000

Position accuracy for map scale 100,000 50,000

Elevatioa accuracy for contour interval 200 a 50 a 4=1 ••
The 6 inch system could satisfy the requirement for world wide

small scale 1:1,000,000 and 1:500,D03 napping. The much more serious

problem of medium scale 1:250,000 mapping could be satisfied by the 12

inch camera system which also has the important capability of providing

adequate geometric control for the preparation of large scale 1:50,000

and 1:25,000 maps. The content for these large scale maps could be

provided by the 24 inch camera systems. Thus an ideal system would be

composed of both the 12 inch and 24 inch cameras. This would largely

satisfy all current requirements for mapping at scales smaller than

those needed for actual engineering construction.

What Are The Prospects

A year ago, the Department of the Interior announced its project

EROS - for Earth Resources Observational Satellite. .Although a number-of

proposals are under consideration, the most promising seems to be a camera

system designed and built by RCA Astroelectronics Division. The camera is

the ultra sophisticated child of the highly successful camera used in the

now operational TIROS TV weather satellite system. The characteristics of

the TIROS and the new vidicon are as follows:

COMPARISON OF TIROS AND EROS VIDICONS

TIROS EROS

Tube diameter- 1/2 inch 2 inch

Picture area 1/4 inch square 1 inch square

Resolution 400 lines 8000 lines

Resolution elements 160,000 64,000,000

Sensitivity 0.4 ft. candle sec. 0.01 ft. candle sec.

•

-12-
In order to meet the requirements of a large number of scientists

in the fields of agriculture, forestry, geology, geography, hydrology,

and other natural resource disciplines, it is proposed to use three cameras

to acquire photography in three different spectral bands.

These bands are selected to provide:

The sharpest demarcation between land and water areas,

The maximum discrimination of vegetation types,

(c) The greatest penetration of water.

Each frame of the proposed pictures will cover an area of 96 x 96 nautical

miles and will provide a ground resolution of 100 to 200 feet from a

circular orbit at 300 nautical mires. The orbit inclination will be 97.

sun synchronous so that the illumination conditions will be identical for

ad;acent orbital passes. The satellite will weigh about 850 pounds,

and can be launched by a Thor Delta from the Western Test Range. Solar

cells and batteries will provide power for the cameras and for a 4

megacycle communication bandwidth required to transmit the pictures to

ground stations. .A video tape recorder will store the pictures until the

satellite is within range of a ground receiving station. A lifetime of

at least one year is planned so that repeated coverage can be obtained

to determine the time variant characteristics of areas of special interest.

NASA's Lunar Orbiter program has clearly demonstrated the

ability to acquire and transmit extremely high resolution photographs

from space. However, photogram=etrists have learned to be suspicious of

the geometric integrity of transmitted and reconstructed pictures. This

fact and the lack of adequate stereo overlap makes the use of EROS photography for geometric mapping marginal.

-13-
In the Apollo program, it will be necessary to perform a

number of Earth orbit missions to check out various parts of the system

and procedures. XASA is studying the possibility of using one of these

missions to carry a number of Earth sensing experiments. Among these

would be a 6 inch focal length, 9 x 9 inch format, cartographic camera

with a coupled stellar camera.

A study has been performed by Martin-Marietta Corporation to

define the integration of this experiment with the other sensors and the

spacecraft. They have proposed a new equipment carrier module which would

replace the Lunar Module. It will consist of a welded aluminum truncated

cone enclosure 84 inches in diameter at the experiment mounting end

and 110 inches long overall. •A truss,iehich will support the cone in

the spacecraft adapter, will also serve to support all experiments not

requiring in-flight access or pressurization. The cone itself will be

pressurized and the camera system will be among the experiments in the

pressurized section. The astronaut will have access to the experiment

section through the air lock for such functions as changing the Mit

magazines.

In operation the command and service module with the equipment

carrier moduie. will have its longitudinal axis normal to the Earth's

surface and the cartographic camera will look. down through the base of

the cone. This configuration will provide the astronauts maximum

terrain visibility through the Command Module windows.

The proposed parameters for the Apollo mission are:

APOLLO MISSION PARAMETERS

Cartographic camera

6 inch focal length, 9 x 9 inch format

Orbit

140 n.m. circular, 50° inclination

(provides complete U. S. coverage)

-14-
• Lifetime

. 14 days

(provides 2 looks at every point)

Film load

900 frames each covering 210 x 210 n.m.

(limited by stowage in CM for return to Earth)

Total coverage

13 million square miles

Proposed launch date

Spring 1969

Manned missions are extremely costly to fly, and they are restricted

in the amount of photographic film and other data which can be physically

returned to Earth. For these reasons. NASA is also considering unmanned

photographic missions, and a study has been performed by Lockheed Missiles

and Space Company to define the characteristics of such a system.

NASA envisions a spacecraft, illustrated by Figure 4, carrying

three 6 inch focal length, 9 x 9 inch format, cartographic cameras._ The

use of three cameras will provide the multi-spectr

•

 al capability for resource evaluation in addition to cartography.

The exposed film would be returned to Earth in a data recovery

capsule. This part of the system has been developed and proved by General

Electric Re-entry Systems Division for use in several Air Force experimental

programs.

The general procedure is to mount the experiment instrumentation

(cameras in this case) in the spacecraft and to feed the data (exposed film)

to the attached re-entry vehicle. When the data acquisition mission is .

completed, the recovery vehicle is separated from the spacecraft and re-

.

enters the atmosphere. A parachute is deployed and the data package is

snatched by aircraft. The spacecraft itself is then deboosted and splashes

into the ocean. The recovery technology is clearly available. It remains

-15-
• FILM DIUTE

REEN1RT VEHICLE

Figure - Schematic for Film Recovery Satellite

METRIC CAMERAS

STELLAR

ATTITUDE

CAMERA
to adapt the re-entry vehicle to the handling of photographic film. It

is estimated that between 100 and 200 lbs. of exposed film could be

returned from a single mission. With the vehicle in a sun synchronous

polar orbit, with a lifetime of 3 weeks, a single camera could photograph

nearly 30 million square miles. If the film load were divided among three

cameras, the system could cover the entire United States in several spectral

bands with a high probability of getting successful coverage.

what Are the Chances of Success 

When a spacecraft is in orbit, its lifetime is necessarily limited.

Since all costs have been accrued when the lifetime is terminated, the

success depends entirely upon whether the mission objective has been accomplished

during the lifetime. For a photographic mission, this is critically dependent upon the weather--or more specifically on the percentage of cloud free

area during the daylight hours. Many studies of world wide cloud distribution have been performed, and the results of a number of them may be

summarized as follows:

With one look, a satellite will probably photograph 50

percent of the desired area. A second look will probably get 50 percent

of the remainder; a third look 50 percent of what is left. This series

would require an infinite number of looks to get 100 percent coverage.

On the other hand, 4 looks would give 94 percent coverage and 5 would

give 97 percent.

To acquire photography at least 64 percent cloud free

over the United States, a satellite launched in September would require

2 looks for the total southwest and • major portion of the midwestern

and eastern sections; • 3 looks would get most of the northwest but would

still lose a section through Texas, Missouri, and the Dakotas.

(3) The probability of successfully photographing an area as

a function of its percentage of possible sunshine is:

-17-
Percent of Probability of success

sunshine 2 looks 4 looks

Over 90 0.99 0.99

80 - 90 0.95 0.99

70 - 80 0.90 0.99

-60-70 0.82 0.96

30 - 60 0.75 0.93

(4) The percentage of coverage with an 0.9 probability of 1 or

more cloud free passes is:

2 looks 4 looks

U. S. - summer 84Z 98.52

U. S. - winter 20 77.5

World - all year 17 65

As a generalized conclusion, these studies seem to converge

on the fact that a system providing 4 looks at the areas of interest is

approaching the point of diminishing returns. With a 4 week lifetime

for the spacecraft, the 12 inch camera would sec 2 looks, and the 24

inch camera 1 to 4 looks depending upon the configuration selected. One

or two satellites would probably achieve adequate coverage of all areas

which are not perenially cloud covered. To hope to photograph such

areas from a satellite is probably not realistic.

It Economically Feasible 

Presume that an unmanned satellite is launched carrying both

the 12 inch and 24 inch camera systems, and that a 200 lb. film load'is

distributed so that both cameras would be able to photograph the same

total area. Using thin bass black and white film and the orbital altitude

of 125 a.m., each of the camera systems would be able to photograph 9 x 106

square miles. If the total mission cost is $15 x 106, the photography

costs $1.67 per square mile for double coverage. Even if the photography

is only 50 percent useful, the cost is $3.34 per square mile.

1

-18-

I
Compared to these costs, conventional aircraft photography in

the U. S. costs the U. S. Geological Survey between $2.50 and $4.00 per

square mile on contract basis. Foreign photography, based on 650,000

square miles in South America, costs the U. S. Air Force about $12 per

square mile for single coverage. Thus purely on the basis of cost per

square mile, space photography, particularly of remote areas, is clearly

more economical.

The problem with these figures is that 1000 square miles from

a satellite would cost the same $15 x 10 6

 as the 9 x 10

6

 square miles.

Looking at the problem in this way, and using $4 per square mile as the

cost of airplane photography, the breakeven point would occur at 3.75 x 106

square miles. That is, if more than 3.75 x 10 6

 square miles of photography

are required the satellite is the economic way to get it.

The fact of the matter is, however, that the total map producing

capability of the United States could not turn out 3.75 x 106

 square miles

of conventional mapping in a year. However, the basic reason for this is

found in the number of photographs involved. •

Figure 5 shows the coverage produced by conventional aircraft,

photography compared to that which would be given by the 12 inch frame and

24 inch panoramic cameras. Also shown is the area of a standard 1:250,000

scale map sheet.

To photograph the 3 x 10 6 square miles in the United States,

• standard L inch mapping camera flown at 30,000 feet would require a

minimum of 100,000 stereo pairs. The proposed 12 inch camera system

flown in a satellite would cover the same area in about 500 stereo models.

To process 100,000 stereo models is unreasonable, whereas 500 is clearly

within the capability of most agencies.

In addition to the simple processing of 100,000 stereo models,

mapping by conventional photogrammetric procedures would require several

hundred thousand ground control points at about $300 per point, whereas

the 500 stereo models of space photography could be compiled with a few

thousand control points. Of even greater importance is the fact that

-19-
FLIGHT

1 DIRECTION

24" PANORAMIC 74' SWEEP

24" PANORAMIC 44• SWEEP

0.V

1:250.000

I

MAP QUAGMANGLE

I

f • 12 INCH

9 n 14.5 INCH FORMAT

f INCH.

9 INCH FOR

H • 30.000 FEE

ES f • 6 INCH

9 • 9 INCH FOR.

H • 12,000 FEE'

H n 125 N.M.

Figure 5 Comparison of Coverage Obtained

From Aircraft and Satellites
the control points for the space photography could be established by

triangulation of the photographs themselves. This is not possible With .

the conventional photography because the errors in the triangulation

accumulate with the square of the number of photographs involved. This

is basically what makes it possible to predict that space photography

will be able to do the job st all.

The remaining question is whether the 500 stereo pairs will do

the same mapping job as the 100,000. This is the great imponderable,

' because there is no experience in mapping from space photography. The

figures indicate that the proposed systems will probably do the job, if

other parts of the mapping system are given the same attention as the

spacecraft and its cameras.

The final fact is that with space photography, useful products

can be made which are totally impossible from conventional aerial photo- .

graph,. These include:

A synoptic mosaic of continental areas at scale of 1:1,000,000

or 1:500,000 which is obtainable from the 6 inch photography.

Photogrammetric control for maps at scale 1:24,000 anywhere

in the world. This is obtainable from the proposed 12 inch

photography.

Compiled maps at scale 1:250,000 anywhere in 

▪

the world. This

is also obtainable from the proposed 12 inch photography.

Large aisle, rapid response, mosaics and revised maps for

any selected area in the world. These are obtainable from the

proposed 24 inch photographs.

No economic analysis of space cartography would be complete

without consideration of the data processing part of the map production

routine. Only about one third of the current processing involves the

photographs. A cartographic satellite does not improve the remaining

two thirds. Nut it drastically alters the inputs, both in rype and in

quantity. Me formats and focal lengths of space photography

▪

may be,

to a large extent, Incompatible with the current data reduction instrumentation. Clearly, if satellite photography is to be useful on a pro-

-21-
• •

duction basis, detailed consideration and planning is required throughout

the whole course of the map making cycle. This extends as far as a reeducation of map users who say find it necessary to revise their notions

of what is an acceptable asp.

Conclusion 

We see before us both an opportunity and a challenge. We have

the prospect of obtaining a knowledge of the Earth's surface and its

resources in detail which we could not have imagined ten years ago.

Our generation may be in the position to complete the world mapping

task which was started 5000 years ago when the. Babylonians first put

sty/us to clay to guide a caravan across the desert.

• .0

-22-
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PHOTOGRAPRETRIC GEODESY

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Space and Infatuation Systems Division'

Alexandria, Virginia

Annual Nesting

American Society of Photogranmetry

!Web 1968

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PNOTOORANNETRIC MODEST ON THE NOON. • • a. • r•

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- Introduction .•

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There can be little doubt that the major technological achievement of

this decade will be the landing and recovery of men from the surface of the Moon

by NASA's project Apollo. The recent successful tests of the Saturn V booster,

the Apollo capsule, and the Lunar Module have made it evident that it is only

a matter of a few months until this accomplishment will take its place in history

beside the travels of Marco Polo, the discovery of America, the exploration of

the Pacific, and the voyages to the North and South Poles. Every one of these

historical ventures was followed by a sustained program of exploration and eventual

utilisation of the areas discovered. Velum the initial Neon landing is followed

by a similar cycle of exploration and utilisation of itirresources, our generation's

technical triumph will go down as nothing but an enormously expensive gri6dstand plc

NASA has, of course, recognised this fact and has been actively studying

the course of future lunar and planetary exploration. The ultimate goals of the

nation's space program have been defined by the President's Science Advisory

Committee fl) as a search for the answers to the questions:

Does life abide in places other than the Earth, and if ,

so whet is its nature, how did it evolve and what are

its probable forms slimmers?

What is the origin and evolution of the universe, aid

what is its ultimate destiny? What is the place of our

Sun and solar system in it? Do natural laws as we know

them on Earth indeed govern the behavior of every

observable pact of the vastness of space?

What are the physical conditions on the Moon and on

the other planets in our system, and her did our solar

system evolve? What dynamic relationships between the

Sun and the planets shape their environments?
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••• V••• • • These broad objectives will be achieved by systematic pursuit of more :',. ."..

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. .• limited specific objectives in the scientific disciplines of geology, geophysics, •• :.

S...v6.1poilipsistry, bioscience, particles and fielda, and astronomy. Although geodesy:. ..:,,

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for their experiments.

The Space Science Board of the National Academy of Science net at Woods

Kole, Wassachusetts, during the summer of 1965, to relate these broad goals to the

lunar exploration program in the post Apollo period. The specific objectives which

they defined for the !bon are:

Determine the origin and history of the Moon;

Deteralie the composition, structure, and processes

of the lumar surface;

Determine the composition, structure and processes

of the loser interior;•

Determine the existence and the structure of any organic

compounds indicating the presence of life on the Moon.

In order to recommend experiments which would implement these basic

objectives, a conference of scientists interested in lunar exploration was convened '

by NASA in Falmouth, Massachusetts, July 19 - 31, 1965 [2). A second conference

on loner science and exploration was convened at Santa Crui, California, July 31

to August 13, 1967, to update and revise, as necessary, the findings of the Falmouth

conference (3]. Both conferences contained Geodesy and Cartography Working Groups

whose reports document a set of scientific objectives in this area. In addition,

the Geology end Geophysics Working Groups at the two conferences imposed requirements for cartographic support of their own programs. In many inatances, this •

cartographic support is implied rather than stated explicitly.

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Requirements for Lunar Geodesy and Cartography 

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At the Falmouth conference the Geodesy/Cartography Working GroUpinutlinei:

the essential steps in the development of cartographic knowledge of.teh Noon:.

4 ,

.

Establish a selanodetic coordinate system related

unambiguously to the right ascension-declination

system.

Describe, in sufficient detail, the gravitational

field of the Moon.

Derive a reference figure with respect to a point

which is representative of the Noon's center of mass.

Establish a three-dimensional geodetic control

system over the entire lunar surface in tares

of latitude, longitude, and height above the

chosen reference figure.

To complete these tasks it would be nec

▪

 essary to:

Define and develop systems for the collection

of raw data which are suitable for compilation

of topographic maps of various scales, using

photogrammetric methods.

Define and develop techniques and instruments

for the reduction of acquired data and presentation of these data in useful form.

Select and implement additional geodetic measurements to provide complementary results for analysing

in depth such phenomena as rotation and physical

librations of the Moon, lunar tides, etc.

Establish specific research and development programs

which show promise of effecting significant improvements

in knowledge of lunar geodetic parameters.

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At the Santa Crux conference the Geodesy/Cartography Working Group:

recognised the common metric character of a group • of vitally interrelated topless'' • .

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The lunar ephemeris describing the position of the .

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center of we of the Mon.

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The angular orientation and motion of the'Moon about

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its center of mass.

The gravitational field of the Noon.

The size. and shape of the Moon's surface.

They described the present state of knowledge on these topics, and, most importantly,

defined the types of 11211•111011•Nate which would result in a compatible accuracy for

each of the parameters.

The Geology Working Group of the Falmouth conference recommended a

systematic program of lunar mapping at various scales. At the Santa Crux

conference, the group modified their earlier recommendations, and the current

map requirements are:

Orthographic, Mercator, and Polar Stereographic

projections of the whole Moon (approximately 10•sheets)

at scale 1:5,000,000.

Complete topographic coverage of the Moon (144 sheets)

at scale 1:1,000,000.

Coverage of approximately 20 areas of interest as Apollo

Applications Program (AAP) landing sites and traverses

(approximately 100 sheets) at scale 1:250,000.

Coverage of central parts of 20 areas of special interest

(approximately 20 sheets) at scale 1:50,000.

Coverage of landing sites in the central portion of

LAP sites (80 sheets) at scale 1:5,000.

.

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Contour intervals were not specified for any of these map series, but are expected

to be compatible with the character of the terrain.

In addition, the Geology Working Group spelled out the requirements

for an Earth based Scientific Data Center which would have, among others, the

capability of producing large scale topographic saps in near real time from TV

or electromechanical scanner data obtained from landed and mobile vehicles.

•

Before defining systems for producing map data it is appropriate to

translate these map requirements into photogrammetric terms. Eased On U. S. map

accuracy standards, the standard error of positional coordinates may not exceed:

a • 0.03 mm x map scale umber,

and the standard error of elevations should not exceed:•

o

h

 • 0.3 x contour interval.

The ground resolution required for compiling terrestrial maps is dictated

primarily by the cultural features (roads, buildings, etc.) which must be included.

These are nearly independent of nap scale, and hence required resolution is not

linearly related to map scale. On the Moon, however, cultural features are expected

to be absent, so that a linear relation seems justified.

The smallest feature which could be depicted on i map would have a least

dimension of about 0.25 mm. In order for an object to be photographically identifiab

it most be imaged by about 5 resolution elements. The required surface resolution

for photography is thus:

ground resolution • 0.05 am x map scale number.
The reasonableness of this figure may be judged by noting that it means the map

should have a revolution of 20 A/mm. This is • little batter than the resolving

power of the unaided human eye. Consequently an orthophotograph (Which seems the

most useful representation of the lunar surface) made to this criterion would •

contain all the information which a human could extract without enlarging the

map seals by magnification.

The criteria represented by these formulas may be applied to the standard

. map scales and contour intervals. The results are given in Table 1.

Table 1

MAP ACCURACY REQUIREMENTS

Map o resolution c.i. a

P h

Scale (meters) (meters) (meters) (meters)

2,500,000 760 125 1000 300

1,000,000 300 50 500 150

250,000 76 12.5 100 30

100,000 30 5.0 50 15

50,000 15 . 2.5 25 8

25,000 7.6 1.3 10 3

10,000 3.0 0.5 5 1.5

. These represent the numbers against which the performance of a photogrammetric system

should be evaluated.

•

Lunar Camera Systems 

It is abundantly clear that many of the geodetic objectives and most of

,

the cartographiC requirements can be satisfied by using orbiting spacecraft as a.

platform for metric cameras and other sensors. A great number of proposals for

limner camera systems have been made ranging from 1 1/2 inch to 144 inch focal

length and including both transmitted and recovered photography. These various

suggestions may be played against the geodetic and cartographic requirements and

the restraints on photography imposed by lunar photometric response and illumination,

-6-

•
•

•

. vehicle attitude and stability, lunar rotation, image motion, file response, etc.

Without going into detail am all the analysis involved, several eamere systems

emerge as clearly desirable:

For complete lunar coverage and small scale mapping,

a 3 inch focal length, 4 1/2 x 4 1/2 inch format •

vertical camera.

For complete lunar coverage and medium scale mapping,

a 12 inch focal length, 9 x 14 1/2 inch . format vertical

camera.

For independent determination of mapping camera orientation.

a pair of synchronised stellar cameras of 6 inch focal

length, 70 mm format.

For large scale site napping, a pair of 24 inch. 4 1/2 x 9

inch format convergent cameras.

•

Because of the wide availability of 6 inch focal length, 9 x 9 inch format cameras,

they are considered an acceptable substitute for the 3 inch cameras, and a'fall .

back solution in case vehicle or mission restraints make it impossible to employ

the 12 inch camera system. Physical film recovery is considered essential to

assure cartographic integrity of the photography.

In addition to the cameras, the spacecraft will require transponders to

permit accurate orbital tracking, a vehicle clock capable of being related to

ephemeris time with an accuracy of + 0.001 second, and a pulsed altimeter capable

of about + 2 meter accuracy. The clock and altimeter readings should be

synchronized with the camera exposure and recorded in a data block on the film.

In order to provide complete coverage of the lunar surface, it is

apparent that the spacecraft will have to be in a near polar orbit, and if.total

coverage is desired from a single mission, the time in orbit would be a domplete.

lunation of 28 days. Furthermore for efficient coverage, the altitude should
be such that the width of the area covered by the photography is some multiple

of the approximately 33 km separating consecutive orbital passes as they cross

the equator. For the proposed camera systems this altitude works out to be 93 km.

Obviously if the sidelap is near zero at the equator it will be 50 percent at

latitude ± 60• The cameras may therefore be turned off at this latitude on

alternate photographic orbits.

The capabilities of these camera systems are summarized in Table 2.

Table 2

CAPABILITY OF CAMERA SYSTEMS

Item 3 inch 6 inch 12 inch 24 inch

Orbit altitude, km 93 93 93 93

Photograph on orbits 1,5,9 1,5,9 1,3,5 any

Photograph scale 1:1,225,000 1:612,000 1:306,000 1:153,000

Stereo model (I x w)(km) 63 x 140 63 x 140 50 x70 19 x 36

Content for map scale 1:250,000 1:100,000 1:50,000 1:20,000

Control for map scale 1:100,000 1:50,000 1:25,000 ••••nnn

Contour interval (m)

Frames for 100Z cover

Film wt. for 1002 cover (lb)

Geodetic positions o. (m)

100

6000

23

35

50

6000

82

17

30

14,700

322

10

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oboe Noma

Geodetic elevations rob •n••••n••• (m) 36 18 11

It is appropriate to say a few words about the camera systems in the

recently successful Lunar Orbiter series. As is well known, the spacecraft

Contained a medium resolution (4R) 3 inch focal length camera, and a high

resolution (4R) 24 inch focal length camera. The pictures were transmitted and

reconstructed on Earth in framelets which were subsequently assembled into full

or partial frame pictures. The system was designed to photograph potential

Apollo landing sites. It was not designed with cartographic objectives in mind,

and efforts to perform phetogrammetric operations with the records have been time

comsuming and produced accuracies far below those anticipated for the 3 inch and

24 inch systems listed in Table 2. The organizations charged with measurement of
•

the Lunar Orbiter records have achieved 0.030 an standard error in image coordinate

residuals; this is to be compared with the 0.005 mn customarily obtained in

comparable measurements of actual film. In addition to the decrease in accuracy,

the division of the record into a large number of scanned segments has imposed

a tremendous data reduction load. In the triangulation of • single 16 photograph

strip it has been found necessary to measure over 12,000 separate points in order

to remove image nonlinearities, to tie the individual framelets together, and to

provide the required geometrical distribution.

Lunar Cartographic Spacecraft 

At this point in time there are no firm approved programs for new lunar

exploration spacecraft. Many scientists feel that it would be more economical to

develop unmanned, but recoverable, orbiting spacecraft specifically designed and

optimized for particular missions even if this means delaying the exploration by

some few years. However, the Apollo systems hardware already exists,. and the only

serious study to date has been performed by Martin-Marietta Corporation to define

the integration of the cartographic cameras with other sensors and the•spacecraft

(4). They have proposed a new equipment carrier module which would replace the

Lunar Module. As shown in Figure 1, it will consist of a welded alumina. truncated

cone enclosure 84 inches in diameter at the experiment mounting end and 110 inches

long overall. A truss, which will support the cone in the spacecraft adapter, will

also serve to support all experiments not requiring in-flight access or pressurization

Among these may be unmanned subsatellites and lenders to emplace experiments on

the lunar surface. The cone itself will be pressurized and the camera systems will

be among the experieents in the pressurized section. The astronaut will have access

to the experiment section through the air lock for such functions as changing the.

film magazines.

As show .in Figure 2, the command and service module with the equipment

carrier module will have its longitudinal axis normal to the Moon's surface and

the cartographic camera will look dawn through the base of the cone. This
figure 1 - Apollo Equipment Carrier In Lunar Configuration
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Figure 2 - Crew Positions for Apollo Lunar Mission
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configuration will provide the astronauts :maximum terrain visibility through the

Command Module windows. In 12 days of operation the system would acquire cartographic quality photography of 40 percent of the Moon's surface. It could perform

all the required special site photography.

Data Reduction of Lunar PhotoeraRhi 

The Lunar Orbiter records are the only Moon photography which will be

available for several years to come. The Manned Spacecraft Center, the Army Map

Service, and the Aeronautical Chart and Information Center are making valuable

nap products from these records:

Site Geometry - Triangulation of the MR photography of the first

three Lunar Orbiter missions and the scientific sites photographed

by Orbiter V provides photogrammetricdlly established control for

the individual areas covered by the missions. The resulting topographic data points are internally consistent by virtue of the

photogrammetric constraints, but are related to the Moon's center

of mass only to the extent that the input spacecraft positions

are given with respect to the center of mass. Relative uncertainties

of the positions and elevations so determined are presently on

the order of 150 meters in position and 300 meters in elevation.

Uncertainties of elevations with respect to a lunar mass centered

coordinate system are on the order of 500 meters. These uncertainties

apply to all asp and mosaic products based on this triangulated

control.'

1:100,000 scale uncontrolled mosaics. These are produced on a

quick response basis using the MR photography to provide an overall

view of the area photographed at a common scale.

1:25,000 scale uncontrolled mosaics. These are produced on a

quick response basis using the MA photography.
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1:100,000 controlled mosaics. These are produced utilising the

control established by the triangulation of the MR photography.

1:25,000 controlled mosaics. These are produced from the RR

photograph utilizing the control established by the triangulation

of the MR photography.

1:100,000 topographic maps. These are produced utilising the MR

photography and the control established by the triangulation of

the MR photography. Compilation is by conventional stereoscopic

plotting instruments. They contain 100 meter contours and shaded

relief rendition.

1:25,000 topographic maps. These are produced from the RR photography of Mission r, and are scaled to the control established

by triangulation of the MR photography. Originally, contour data

was to be provided by photometric analysis of the RR photography,

but this has not yet become operationally feasible. Contours (or

more appropriately, form lines) at 25 meter intervals are compiled

from the MR photography at the same time the 1:100,000 maps are

produced. The saps also contain shaded relief rendition. These

map products have been dropped from the later missions.

From Orbiter IV photography and the high altitude photography of Orbiter V,

the following products are under consideration:

Lunar Control Net - Although the geometry of Orbiter IV and V MR

photography is poor from a photogremmetric point of view, the fact

that nearly the whole Moon is covered makes it attractive to

attempt to establish a complete lunar control net. This net should

be more extensive and consistent than the present nets established

by the Department of Defense Agencies from Earth-based telescope

photography. The accuracy is expected to be comparable with the

best positions and elevations in the current network.
The approach is to use strip triangulation to provide initial values for

a more comprehensive block adjustment program. An alternate'apprOach to the

development of a complete lunar control net is to employ the MR pictures - from

Orbiter IV and V. These pictures have inadequate overlap to permit a conventional

photogrammetric triangulation, and consequently will be totally dependent upon

orbital position data. However, incorporating than in a triangulation program

with adequate orbital constraints will produce consistent results. Preliminary

analysis indicates that accuracies of about 250 meters may be expected.

Controlled Mosaic - Based on the triangulated control

net, it is feasible to produce a controlled mosaic of

the near side. of the Moon at a scale of 1:1,000,000

using the HR photography of Missions IV and V.

Atlas - A photographic atlas of all Orbiter IV and Orbiter V

far side photographs is obviously feasible. This would

simply be an assembly of the photographs, indexed and

keyed to a lunar coordinate system.

Lunar Astronautical Charts - The current lunar map series

is the Lunar Astronautical Charts (LAC), scale 1:1,000,000

consisting of 44 sheets covering most of the visible face

of the Moon. This series is produced from Earth based telescope photography supplemented by visual observations. One

of the most valuable applications of Lunar Orbiter photographs would be the revision of this series, and extension

of coverage to the polar areas and back side. This should

be feasible using the control net described above, and the

surface detail from both the MR and HR photographs from

missions IV and V.

When new lunar photography of high geometric integrity, supported by

stellar attitude photography, and laser or radar altimetry becomes available,

a whole new set of photogrammetric problems will require attention. No Matter

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how sophisticated the sensors, or how elegantly the data are acquired, their

usefulness can be either negated or enhanced by careful consideration of the data.

reduction problems.

The principal objective will be to provide a unified geodetic control

syitem related to ' the Noon's center of mass, and serving as a framework for

compilation of high accuracy maps. Involved in this problem are several other

considerations:

Celestial orientation of the Moon's axis and short •

term rotation (physical librations);

Mathematical reference surface;

Relation of center of mass to center of figure.

Contributions to knowledge in each of these areas can be obtained from the photogrammetric reductions, and in theory at least, they could all be included as

additional unknowns in one grand least squares solution. Ho ever, other types

of observations and analyses will also be contributing to determination of these

quantities. It therefore seems advantageous to solve the photogrammetric problems

individually so that the values obtained thereby may be compared and combined

with those from . other observations systems.

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Refinement of Lamar Ephemeris by Star-Surface PhotosraphY 

Present knowledge of the orientation of the axis:of the Moon in the

celestial system and the rotation about the axis is not better than approximately

30 seconds of arc. To fully exploit the directional accuracy of the stars in a

Noon centered system, considerable improvement in determination of the Moon's

axial orientation is needed. This can be provided to a level of accuracy comparable

to the angular accuracy of the photography by analysis of simultaneous starsurface photography covering a large part of the Moon's surface.

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The basic approach is to compute in a Moon fixed coordinate system by

classic photograsmetric techniques the relative orientation between two terrain

photographis exposed at some interval of time. The relative orientation of the

same two terrain photographs can also be computed in the celestial coordinate

system from the corresponding stellar photographs. The differences between the

two relative orientationa can only be ascribed (apart from inaccuracies in the

solution) to the Moon's motion in the tine interval between the two exposures.

Every pair of conjugate photographs would provide a set of observation equations.

A least squares solution would be employed.. The initial values would be the

Moon's orientation and rotation rate as extracted from the American Ephemeris

for the midpoint of the mission. The unknowns would be corrections to the initial

values plus the constants in a time polynomial for each of the angles. Although

a linear polynomial should be sufficient for missions of short duration, second

degree terms might be employed for missions up to a full lunation since 80-percent

of lunar motion anomalies have a period of one lunation.

Not all photographs would be used. At latitude + 60' photographs

from adjacent orbits will have SO percent sidelap and 4 to 8 hours'will have

elapsed between adjacent photographs. A solution involving these two lateral

bands of photography would have good geometric strength and time distribution.

Orientation of Lunar Photography by Simultaneous Stellar Photography 

The purpose of stellar photography is to provide an independent determinati

of the attitude of the cartographic camera at each exposure, and thereby reduce

the error propagation in a photogrammetric triangulation. The orientation values

required are those with respect to the principal axes of the Moon, and their

calculation must take into account the parameters of the lunar ephemerides, as

determined in part by the preceding analysis. This simply means that stellar

coordinates must be related to the Moon's equator, and a time scale determined

by the lunar rotation rats.

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Photogramaetric Triangulation Program Optimized for. Lunar Application 

To properly exploit the total photographic coverage Of the Noon, synchronized

stellar photography, and laser or radar althestry, expected to be provided by the

Apollo Applications Program, a new integrated triangulation program is indicated.

What is required is a photogrammstric triangulation program which will be selfsufficient, which will absorb all observations of accuracy comparable to photogrammetry, and which will not be dependent upon control points on the surface in

order to reach a solution.

To develop such a prograa, a detailed study is required to determine

precisely the requirements and the means for implementation. In this analysis,

consideration should be given to the following:

A choice must be made in the type of photogrammetric condition

equations. Collinearity equations are simpler to administer

programmatically. However, they require approximations for all

ground points, and corrections to these initial ground point

coordinates become additional unknowns in the solution. (They

do not, however, increase the order of the matrix to be solved.)

Coplanarity and scale restraint equations involve only the

exposure-station parameters without requiring ground point

approximations. However, they result in complicated program

bookkeeping because each equation involves several exposure

stations. A system based on these equations would also

include collinearity equations to accommodate ground control

points if they were available. It may be necessary, for example,

to enforce the ground coordinates of one point in order to relate

the triangulation to a lunar latitude and longitude graticule.

If the triangulation is based on coplanarity and scale restraint

equations, it would be necessary to perform space intersections

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to determine ground point coordinates subsequent to the computation

of air station positions and camera attitudes.

The system must be capable of absorbing measured scale distances.

The most probable source of these will be the laser, or radar,

altimeter readings taken in conjunction with the photography.

However, tracking data may also provide scale distances which

may eventually be comparable in accuracy to altimetry. Either

type of observation should be acceptable.

The system should accommodate weighted, functionally described,

or enforced camera attitude data. If preceded by proper analysis

of lunar motions, camera attitudes obtained from stellar photography

may be sufficiently accurate to be enforced rigidly in the solution,

thus eliminating three unknowns per photograph. Spacecraft

attitudes usually vary slowly, and a valuable approach is to

describe the change in each attitude angle by a Fourier or

polynomial function. The constants of these functions then replace the actual angles as unknowns. To make the system

flexible enough to handle small blocks or situations where star

camera or other attitude data may not be available or useful,

it should be possible to solve for the attitudes, but even in

this situation, it should be possible to weight the initial

approximations.

A modular program permitting either of these approaches to

the computation of orientation angles would be desirable.

It should be possible to impose orbital constraints on the

air stations. This will both reduce the number of unknowns

in the solution and will strengthen the geometry. It is the

obvious way of introducing tracking data into the solution.

Considerable study is needed to determine the best way of

introducing such constraints. Initial Keplerian elements
with time polynomials for changes in the elements is an appealing

approach. Such time series are capable of absorbing the effects

of large scale gravity field anomalies. me number of orbital

passes to be included in a single orbital function is also a

subject for serious study.

Continued tracking of lunar satellites will provide gravity

harmonics independent of any photogrammetric triangUlation.

Depending upon the magnitude of the effects which this gravity.

field will have on exposure station positions, it may be desirT

able to include the gravity model coefficients as weighted

parameters in the orbital model.

There is no thought that the development of such a computer

program would start from scratch. Many elements of the program

are already available. But • thorough analysis is required to

provide an optimum operational program.

In addition, study needs to be devoted to define the data

handling routine for a task of this magnitude. Undoubtedly,

it would not be advisable to start out initially with a large

solution involving the total Moon coverage. A probable procedure

would be as follows:

Correction of observed image coordinates for film distortion, reduction to principal point, blunder eliminations, etc.

Computation of stellar attitudes and transformations .

to terrain camera attitudes.

(3) Sequential strip triangulation of individual half

orbits to edit data and obtain good approximate values.

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Triangulation of blocks containing up to a few hundred

photographs. These could either be parallel strips of

half orbit length, or shorter but wider blocks consisting e •

of adjacent parts of several orbits. Probably both would

be tried, but in either case considerable overlap would be

provided between adjacent blocks.

Simultaneous solution of all photographs utilizing all

available constraints.

The output of this program would be a geometrically homogeneous set of

coordinate values for all points on the lunar surface included in the data reduction

scheme, and position and orientation of the exposure stations in the same coordinate system. With the stellar attitudes based upon analysis of the Moon's axial

orientation, absolute lunar latitudes of the triangulated points will be correct

within the errors of the orientation computation and the triangulation variances.

Relative lunar longitudes will be correct to the same tolerances. Absolute

longitude values will be related to a defined meridian based upon a photographically

identified point. A landed spacecraft seems to be a good choice for such an

initial meridian.

If a 12 inch focal length metric camera constitutes the basic cartographic

system, the predicted standard error of photogrammetrically established control

points will be about 10 meters in position coordinates and 15 meters in elevation.

This is more than an order of magnitude more precise than a control system which

might be obtained from the current Lunar Orbiter records.

Lunar Mathematical Reference Surface 

Once a homogeneous set of coordinates values for points covering the

lunar surface is established by the photogranmetric triangulation, it will be

feasible to establish a mathematical reference surface, essentially by a surface

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fitting procedure. 'A sphere, spheroid, or three axis ellipsoid could be fitted by

minimizing the sum of the squares of discrepancies between the triangulated points -

and the selected reference surface equations. The equation type providing the

minimum residuals could be adopted. If the triangulation is based on stellar

directions, thn_orientattcs of the reference surface will be with respect to the

Moves axis of rotation. If, furthermore, the lunar gravity model or orbital

tracking data are imposed in the triangulation, the origin of the reference

surface will be the Noon's center of mass.

Cartographic Plotting 

It is apparent that some of the parameters of proposed lunar photography

are not directly adaptable to the types of photegrammatric plotting equipment

generally available. Consideration needs to be given to the problems:

Accomodation of new focal lengths and formats.

Handling of lunar surface curvature.

Restrictions imposed by shadows in low sun areas.

Orthophotomap, pictomap, or mosaic presentation of

planimetry.

Contours, slope roues, surface texture, shaded relief

presentation of topography.

Automatic correlation of lunar photography.

Studies of plotting equipment adaptability should be carried out in parallel with

development of camera systems and mission plans to provide the basis for selection

of available instrumentation, or the justification for now development.

Lunar Surface Photoarammettv •

Ruch of the work to be perforeed. by astronauts on the lunar surface; and

by manned and unmannedeobile vehicles operating from a landing site, has cartographic

and photogrammetric implicatious. •

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Landing vehicle imaging systems:

The Lunar Module (LM) may be equipped with TV or film

cameras, or an electromechanical scanner whose function would

be to record the landing site. The design, installation,

operation, and reduction of these records will require research

and development.

Astronaut camera and survey equipment:

A wide variety of photographic . and survey equipment

has been proposed for use by astronauts 13] in mapping

a landing site. Mono and stereo cameras, Jacob's staff,

distance measuring equipment,. zenith camera, etc. are

included.

Imaging systems for mobile vehicles:

Proposal* have been made 13] for Local Scientific

Survey Module (LSSM) and Lunar Flying Unit (LFU) for

mobile operation from a landed spacecraft. The LSSM

may have an operating radius of around 100 km in the

manned mode and 1000 km in the unmanned mode. The LFU

will have an operating radius of a few kilometers.

Both vehicles can carry imaging systems which could

produce useful cartographic data. The LSSM would probably have a TV system, the LFU a camera. The LSSM

system may be required to provide real time navigation

data, particularly in the unmanned mode. This would

require near real time mapping at an Earth based Data

Center from TV or electromechanical scanners as a

means of providing guidance and control data to the

active system operating on the lunar surface. A complete

analysis of such a system is required. It should

consider the sensor system, the down and up data Wake,.

the ground data processing equipment, procedures, and •

manpower.
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allan:can ZOMET: OF FHOTOGRANLIATIO Mt N. VUNINUA AVE. FALLS CHURCH, VIREONA 23:481 TIUFHONL 1134461/

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Dr. WIlliam T. Pocore

birocLut

U.S. Geological Survey

Washington, D. C. 20242

Dear Dr. Pecora:

The American Society of Photogrammetry (ASP) is concerned by recent cancellations '

of lectures and withdrawals of articles that deal with the use of satellites for

surveying earth's resources.

Your past support, interest in earth resources satellites (as evidenced by the

EMS Program), and your established leadership in earth science, lead me to seek

your help in clarifying the situation.

bileiload-of-the Department of Geodetic Sciences at

s now Chief Scientist of the Raytheon Corporation . •

tion, was selected as our distinguished lecturer for 1967-68.

s his topic 'Mapping from satellite photographs'.

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The ASP Distinguished Lecture series is jointly sponsored by the National

Science Foundation. tore was similar, in content, to that he

presented and distribute in nt fore before the Annual Meeting of the AIAA,

in Dallas, Texas, November 1967. The first of his series of Distinguished •

Lectures was presented before the Potomac Region of ASP, November 13,1967. A

comprehensive summary of the paper was published in the January 1968 issue of

Photogragmetric Engineering.

Jf

found it necessary to cancel presentation of

in

his paper before the ••

nnua iting of the Canadian Institute of Surveying and Mapping; later he .

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cancelled his scheduled lecture at the University of Delaware, and finally,

rely from our Distinguished Lecture series. Concurrently, •. •

: • :itten version of his lecture was also withdrawn; this papal had . , '41%

been set in iype and was scheduled for publication in the March issue of . ...'n...

Photogrimemetric Engineering. ' .

' 8 ''. ?

,..,

It is hard for us to reconcile NIPactions with his long history of ong 

support to our Society and his repute on for scientific excellence. The

scientific facts and extrapolations contained in' per are generally

"..

known among workers in his field but need wider distr n the form of •

publication in journals and texts, and in oral presentation in 'lecture series. •.--'

We feel, therefore, that it is very regrettable that s found it ••

necessary to cancel additional presentation of his 'me ent peper.

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SAT Coot. Se.

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otocet:ATIO:CM. ceet2:Y . 07 rn0:0Csio'/IV:ev 

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The ate o! our Society is to di .a scientific information and we

purGue this aim with vigor. s assembled information that.is

cic;.i.iflcally sound and shouldbes disseminated. I would like guidance from

awL.I.alstanco you can provide in making it possible to make

'per cvallabla to tha scientific community.

We look forward totes:ins from you in the near future.

Sincerely,

41. _ 

i7 tea; . a.c.f.c.,v

Heinz Gruner, President

American Society of Photogrammetry

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WASHINGTON. D. C. 20301 • #01 - 4 -

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2 5 MAY 19S8

R OF DEFENSE RESEARCH AND ENGINIIIING

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Dear Mr. Gruner:

This is in respo to re ent letter to Dr. Pecora, in

which you discussed per, "Mapping from a

Satellite System."

I have looked into the matter and find that we imposed the

constraints to which you refer because of national defense considerations. As an employee of Autometrics working on Department of Defense projects, immillapublications are necessarily reviewed, in order to protect the national interest, as well

as his own.

Our representatives discussed the security analysis in detail

with n December and he concurred in their findings.

Recognizing the potential awkwardness of the situation -- very

mach as described in your letter -- we worked with 'in

preparing a clearable paper which has been available since February, and which could very well be considered as a candidate

paper for your Distinguished Lecturer series.

I certainly share your interest in disseminating scientific information to the fullest extent possible within considerations of

national security. I believe our action with as been

in consonance with both criteria.

.14~ John S. Foster, Jr.

Mr. Heinz Gruner, President

American Society of Photogrammetry

105 N. Virginia Avenue

Falls Church. Virginia 22046

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