GEODETIC CONTROL GAINS IMPORTANCE AS MISSILE ACCURACY IS INCREASED

• Document Type: CREST
• Collection: General CIA Records
• Document Number (FOIA) /ESDN (CREST): CIA-RDP62-00680R000100250009-2
• Release Decision: RIFPUB
• Original Classification: S
• Document Page Count: 4
• Document Creation Date: December 9, 2016
• Document Release Date: March 28, 2000
• Sequence Number: 9
• Content Type: MAGAZINE

Release 2000/08/23 : CIA-RDP6 -00680R000100250009-2
GEODETIC CONTROL
GAINS IMPORTANCE
AS MISSILE ACCURACY IS INCREASED
World Geodetic System developed by UfAF relates positions of
missile launch sites and targets. Data is lacking on many targets
TonAy's long-range guided rniuiles,
Itrcd for distances of several thou-
!sand miles, may not be expected to /tit
the target right on the nose, but they
are expected to come reasonably cktse.
A pitcher with the best fast bull in the
world is useless if he can't get it near
tla? plate. ?Vithout the element of
control, an IRBM or ICBM is ren-
dered ineffective as a weapon system.
Each missile type produced has its
own inherent or built-in error, prob-
ably rangitig from several thousand
ti et to several miles, according to the
mi.:silt-. This is known as the missile's
ctr. Mar error probability (CE1), a
coin bi nat ion of human ermr. mechani-
cal emir, and the wether factor.
Ndturally, every effort is being made to
reduce this error, in order to reduce the
of missiles r,..quired to achieve
complete destruction of the target.
But no matter how much the missik
is reduced, the missile will not
achieve complete accuracy if the posi-
tional data that determines the trajec-
tory is faulty.
1 he accuracy of this positional data
tor the missile is, in turn, dependent
n the available geodetic control and
the ability to use it. Actually, the
geodetic data presently available can
post( ion a tout _f_lpper
po-
tentiali
rant of targets n -the Soviet Bloc. to
All act ttrac of_Z1041sa. The data
A% ailable on thnetriaming 20 percent,
ti(lweNcr. gives an accuracy only of
from 2.e'Xl feet to an unknown quan-
tity. ?Vhat is worse, many important
targets are included in this group.
Mach 1939
Geodetic error relates directly with
the missile CEP. The method oi
determining exactly how much is
basically simple. Both the geodetic
and missile errors are squared; the
square root of the sum of the squares
represents the total missile CITOf . This
is illustrated by the graph on next
page. In a family of missiles with
large CEPs, the geodetic error is not
significant. In fact, when the geodetic
?rror is less than 3O pet cent o the mis-
sile CEP, an additional error of only
five percent or less or rms. Wu as mis-
sile CEP s are refined, the geodetic
error will naturally assmile ar in-
erelsi4gly greater prominence.
For example, let's assume that for a
certain ICBM the CEP and geodetic
errot are each 5,000 feet. 1 his would
result in a total expected error of some
7,000 feet, not bad if the target hap-
pens to be a large area. Ilowever, in
order to achieve a lengthy pindown of
an enemy !cm( launching base, the
misaile- CEP may be refined as low
as, say, 1,000 feet, which would be a
tremendous achievement. But unless
the geodetic error is reduced, the
missile would atilt have a total error
of over 5,000 feet.
What is toodesy?
Until recently, the science of geodziy
was used mainly as a support of the
mapping industry and was still un-
familiar to operational personnel.
. This situation changed . mildly as
weapon systems whose employment is
dependent on geodetic control brcame
?
operational. Geodesy is defined hs
Webster as "that branch of applied
mathematics which determines, iv
observation and measurement, the
exact positions of points and the
figures and areas of large portions of
the earth's surface, or the shape and
size of the earth and the variation ot
terrestrial gravity." Nlorc simpl \
geodesy provides the framework for
placing all features on the earth in
their correct position. If the geodeti(
information is good, an accurate repre-
sentation of the earth's surface Can be
constructed. Poor geodetic informa-
tion results in an inaccurate repre-
sentation.
It is not difficuit to r,-;dize wit.
accurate mapping depends on ipa)(1
geodetic information. I Ina gi ile tr i
LO sketch even a back yard witho,,t
knowing the measuremetan of tie- lot.
position of the house in relation to the
lot, and the position of trees, ihrubs,
flower beds, and gates. Banicall,
these measurements 1p-rift-sent the
geodetic control of the yard. Where
large areas and greater distances are
involved, more accurate equipment
and techniques are required. But
the bask requirement--accur ate meas-
urements between points?remains
the same.
In the construction of maps, it is
difficult to properly portray the rela-
tionship of features in sketches and
textual descriptions unless the geodetic
control of the area is known.
The task of providing geodetic
control has been carried on
geodesists and surveyors for centuries.
To control an area, thc initial efforts
must Ix made by the surveyor. He
has many tools at hit disposal, such as
Specter 15
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Approved For Release 2000/08/23 : CIA-RDP62700680R000100250009-2
became- obvious that .a unique item
of target .materials would he needed
At the same time, (he operational
commands expressed the desire in
more atcura tr control requirement,
As a mph, the geodetic da.ta ?Iwer
program , was initiated. The ,tt.o.
detic data sheet furnished the opera-
tional commands 'accurate pot,ititmal
information for use in offset anointt
and reference point navigation. 1-lics- -
also enabled producers of target
materials to develop a capability
for working with -accurate geotlet Ic
control.
There was tstill a large problcm to
be solved, however, before (h.. input
data requirement for missiles ci told he
met. It was !veers:Lary to reflt t the
most accurate relationship 4 If tlic
launch site to the target on a common
frame of reference. To ma-01,11)11,h
this, a USAF World Geodetic !Nt stem
was developed. This system
a tnatheimtical surface which moo
accurately reflects the size, shape, and
orientation of the earth'sourfa?.. 111
points that can be related to the l.'s \l
World 'Geodetic System can also be
related to each other. Thus, the po-
sition of launch sites on one continHt
can be related to targets on an,,thcit
continent.
Armed with the positions of launch
site and target on a common (Lona',
and the parameters of the datum.
target trajectory computation fettle]
could now compute a ballistic- +1 .1-
jectory. In 1957, this basic data a as
incorporated into missile d.
sheets?one for the launch Si te and
one for the. target. Additional data
for orientation and calibration are in-
cluded in the launch site data.
By 1962, the built-in error of the
present crop- of U.S. missiles i, es-
1)ected to have been cansicha ad,
minimized. This means that t I tt
value of accurate positional data aII
become even more important and that
errors in excess of 1,000 fcaa will
seriously degrade CFI's. There \till
s continue to be gap in geoortic data
for several years, but new reconna,.-
sance systems, tovet'ier with current
programs, slitrild not ',ills
current control, but stiou'd 'Iii sr
the accuracy prese,u .11
NIcanwhile, a sur-es cow ?i-
quirt-it-lents of ultra sseaoon s5-1. -
of the future are beim.; ?inch(
Even the solution to int,?rplaiiri.h%
travel may well depend on (-mien'
programs designed to provide ;teem ate
positions for all celestial bodies.
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TARGET data sheet (above) skews Issfoneet1ost
transits, steel tapes, geodimeters,theo-
dolites. tellurometers, and gravimeters.
!hese tools permit accurate measure-
ment of distances, angles, ? gravity
forte, and celestial observations. Fur
large areas inaccessible to survey
parties, electronic devices such as
Hiran are used. The data acquired
by these methods are thest given to the
geodesist for resolution.
If the geodetic control problem is
limited to a small area, the labors of
the surveyor are adequate. But when
the area of interest is extended and the
curvature of the earth becomes in-
volved, the geodesist is requested to
provide a base for compilations.
If sing the availabk data, the geo-
desist provides a mathematical surface.
This theoretical surface is the most
accurate representation of the size and
shape of the area for which it was
prepared. The ability of the geodesist
to compute this surface is dependent
on his knowkdge of the true size and
the shape of the earth. As yet, the
complete surface of the earth has not
been surveyed, so its true size and
shape must be estimated from the
caber data available.
All estimates by United States
geodesists have been made thus far
on the basis of a figure called an
ellipsoid of revolotion, which appears
to approximate most accurately the
general shape of the e arth The true
shape of the earth t-ay never .be
accurately determite-o, becaus:. 7tir-
rem meastir.ments of the gravity
held ,nclicates a highly erratic shape.
However, .his ability to measure the
cat th's gravitational field permits the
improvement of relative positions of
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widely separated points. The effect
of gravity on aoronotnic observations
can be minimized, and thus the
astronomic positions reflect more ac-
curately a true position of the surface
tithe earth.
Target vulnerability does not have
to rely on the accurate world-wide
location of the target The correct
relative positions of individual in-
stallations to each other may also
permit an analysis of vulnerability.
During World War 11, knowledge
of the relative positions of installa-
tions within a target area permitted
accurate operational attacks to be
made.
Accuracy requirements had not
been too stringent up to this time,
as manned weapon systems readily
compensate for minor errors in chart-
ing. However, soon after the war,
the accurate position of points outside
of -the target area became important.
Offset bombing and reference point
navigation equipment required an
accurate knowledge of target loca-
tions relative to die offset aiming
points or reference points. This ex-
tension of the controlled area posed
a problem or the chart maker
Specifications for chart production
were tightened, and tachniques and
equipment for chart production were
improved.
Missiles 6angsd
geodetic requirements
Until 1950, graphics ss err satisfac-
tory for accurately pot I raving re-
quired geodetic information. In that
year, the requirements fot missile
Operations were reviessed, AlKi it
Air Intelligence Dige.t
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\ARprOved For, Relwi e 2000/08/23: CIA-RDP62-00689R000100250009-2
FIEF OF GEODETIC ERROR ON MISSILE ACCURACY
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\ttempt to knock out hardened site such as an ICBM
t haw would be made more difficult by a large geodetic
crror. Illustration shows how a missile with a CEP
5,o00 fey( would be affected by a geodetic error of
5,000 fret [SECRET]
March 1959
Stoat 17
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Approved For Release 2000/08/23 : CIA-RDP6400680R00010026000
HOW GEODETIC ERROR ADDS TO MISSILE CE P
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Graph shows how various geodetic 'errors inctca.
1.1 total error for the same missile. Geodetic orroe
1,000 feet would add only 1(X) fret to the mismilr (1%1
but an error of 7,000 Lea adds 3,600 feet of additio.n.
I error.
16 Secret
Al, Intelligence Digest
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