apollo experience report the application of a computerized visualization capability to lunar...

8/8/2019 Apollo Experience Report the Application of a Computerized Visualization Capability to Lunar Missions

1/19

N A S A T E C H N I C A L N O T E NASA TN 0-6853- ---I-. 1 - "04 - gmr _0 - aL O A N COPY: R E T U R N ~ 4 -

KIRTLAND AFB, N. B",s ,-m-3

AFWL (DOUL) w - 3=- 2

APOLLO EXPERIENCE REPORT -THE APPLICATION OFA COMPUTERIZED VISUALIZATIONCAPABILITY TO LUNAR MISSIONS

A '/'/

/ a"


2/19

TECH LIBRARY KAFB,NM

.2. Sponsoring Agency Name and AddressNational Aeronautics and Space AdministrationWashington, D. C. 20546

I11111111111lllll11111nl1lIll

13. Type of Report and Period CoveredTechnical Note- ~ ___--_14. Sponsoring Agency cbde

0333557. . - . ~- - -- - __1. Report No. I 2. Government Accession No. [ 3. Recipient's Catatog No.

- __ ... A- . ~ ~~~. . .~Th e MSC Direc tor waived the use of th e Intern ationa l System of Units (SI) fo r. Supplementary Notes

his Apollo Expe rience Report, because, -i n hi s judgment, use of SI Units would imp air the usefulnessif the report or result in excessive cost.

... . ~ . .-. . - . ~ . . ~~~6. AbstractThe development of a computerized capability to depict views from t he Apollo sp acec raf t during alunar mission was undertaken before the Apollo 8 mission. Such views were consid ered valuablebeca use of the difficulties in visualizing the complex geomet ry of the Eart h, Moon, Sun, andspacecraft. Such visualization capability originally was desi red for spacecraft-attitude verifica-tion and contingency situations. Improvements were added for later Apollo flights, and re su lt swere adopted for seve ral real -time and preflight applications. Some specific applications h aveincluded crew memb er and ground-control-personnel famili arizati on, nominal and contingencymiss ion planning, definition of se condar y attitude checks fo r all major thrust maneuvers, andpreflight star selectior for navigation and for platform alinement.visualization capabilit-standing the geometrical relationships between the spacecraft and the celestial surroundings.

The use of this computerizednould prove valuable f or any future space pro gram a s an aid to under-

-~ .- -. -~ ~ -.17. Key Words (Suggested by Author(sJJ' Attitude Determination* Contingency Mission Planning

_. ~- . -- . .18. Distribution Statement

. _ _ .21. No. of Pages 22. Price1 17 1 $3.0019. Security Classif. (of this report) 20. Security Classif. (of this pael-. . -None I None- _

.For =le by the Nationat Technical Information SGN~CG,pringfield, Virginia 22151


3/19


4/19

CONTENTS

Section PageSUMMARY........... . . . . . . . . . . . . . . . . . . . . . . . . . . 1INTRODUCTION. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1DISCUSSION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2

Program Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3Program Applications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3

CONCLUDING REMARKS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10APPENDIX- UNAR-MISSION VIEW-PROGRAM CAPABILITIES . . . . . . . 12

iii


5/19

FIGURES

%igure123

4

5

6

7

89

View at TLIburn (Apollo 11) . . . . . . . . . . . . . . . . . . . . . .View at entry phase (Apollo 11) . . . . . . . . . . . . . . . . . . . .Views through the scanning telescope (Apollo 11)(a) At 124:40:00 hours ground elapsed tim e . . . . . . . . . . . . . .(b) At 125:OO:OO hours ground elap sed time . . . . . . . . . . . . . .(c) At 125:15:00 hours ground elapsed time . . . . . . . . . . . . . .Views through the alinement optical telescope (Apollo 11)(a) Front detent position . . . . . . . . . . . . . . . . . . . . . . . .(b) Left front detent position . . . . . . . . . . . . . . . . . . . . .(c) Left rear detent position . . . . . . . . . . . . . . . . . . . . . .(e) Right rear detent position . . . . . . . . . . . . . . . . . . . . .(f ) Right front detent position . . . . . . . . . . . . . . . . . . . . .(d) Rear detent position . . . . . . . . . . . . . . . . . . . . . . . .Views during the descent phase (Apollo 11)(a) Front windows . . . . . . . . . . . . . . . . . . . . . . . . . . .(b) Docking window . . . . . . . . . . . . . . . . . . . . . . . . . .Ear th views during translunar coast (Apollo 11)(a) At 2 3 hou rs ground elapsed time . . . . . . . . . . . . . . . . .(b) At 24 hou rs ground elapsed time . . . . . . . . . . . . . . . . .(c) At 25 hours ground elapsed time . . . . . . . . . . . . . . . . .(d) At 26 hours ground elapsed time . . . . . . . . . . . . . . . . .Moon views during translunar coast (Apollo 11)(a) At 70 hours ground elapsed time . . . . . . . . . . . . . . . . .(b) At 72 hours ground elapsed time . . . . . . . . . . . . . . . . .View of Rima Prim (candidate site ) . . . . . . . . . . . . . . . . . .Preflight view of ab or t at LO1plus 2 hours on the Apollo 13 mission(CSM burn) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Page44

555

77

9910

10

iv


6/19

APOLLO EXPER IENCE REPORTTH E A P P L I C A T I O N OF A C O M P U T E R IZ E D V I S U A L I Z A T I O N

C A P A B I L I T Y TO LU NA R M I S S I O N SBy C h a r l e s T . H y l e a n d A l f r e d N. L u n d eM a nned Spacecra f t Ce nte r

S U M M A R YThe complex and constantly varying geometry of the Ear th , Moon, Sun, and space-

craft is difficult to visualize during a lunar mission. The geometry is even more d i f f i -cult to visualize when the reference frame is in the moving spacecraft. A prefl ightknowledge of how the spacecraf t should be oriented with res pec t to familiar objects thata r e visible through the spacecraf t windows o r through the optical instrument s is consid-ered valuable to the astronauts and to the contingency mission planning personnel.Therefore, the development of a computerized capability to obtain this insight w a sundertaken before the Apollo 8 mission. Improvements were added for later Apolloflights, and the results were adopted for seve ra l real- time and preflight applications.Some of these applications have included mission familiarization for crewmembers andmission analysts, establishment of visual attitude-reference capability for normal andabort thrust maneuvers (including the Apollo 13 emergency), and preflight star selec-tion for navigation and fo r platform alinement. Based on th is Apollo experience, it isbelieved that preflight computerized crew visualization capability will be valuable forfuture NASA programs and fo r any large, complex undertaking involving man in space.

I N T R O D U C T I O NIn any large , complex undertaking involving man and his relationship to his sur -roundings, man mus t become as familiar as possible with the expected surroundings andenvironment as pa rt of h is training. In the Apollo Program, the geometrical relation-ships of the various bodies and the attitude requirements we re extremely complicatedand difficult to visualize. In addition, successful operations in cert ain phases of theApollo miss ions depended on the crewmen being able to visualize and understand what

could be seen, either through the spacecraf t windows o r through the optical ins truments.Much of the training fo r this ability w as done by the use of various crew-training simu-lator s. However, these simula tors are of limited use fo r visual training because ofmechanical or physical limits or because of limited availability to analytical and tech-nical personnel other than the crewmen. Thus, a preflight method to depict the viewthrough the spacecra ft window or through the optical instruments at any time during theflight proved to be very helpful in nominal and contingency mission planning and c r ew


7/19

familiarization . Recognition of this need led to the augmentation of a somewhat dormantcomputer program that generated, as the principal output, f ra mes of microfilm contain-ing simulated photographs of objects that could be see n from the spacecra ft at any giventime, Originally, this computer pro gram was developed as an aid in the ea rly Geminirendezvous and docking studies. The objective of having such a program for lunar mis-sions w a s to provide a simple, manual method for the crew men to use fo r a return-to-Ear th maneuver using the observed celestial sphere for orientation in a contingencysituation. Soon, a mo re ba sic application of the pro gra m was recognized by analyticalpersonnel during the development of powered-flight-monitoring procedures. This appli-cation w as to provide the personnel performing analytical studies a method to developa gr os s attitude -check capability before normal maneuver s w ere executed.

D I S CUSS IONAnalytical work on an acceptable method for providing an out-the-window attitudecheck for the Apollo 8 luna r orbit insertion (LOI) maneuver prompted the original full-scale program-development effort. The basic objective w a s the development of a fastand accurate computerized method of preflight visualization of the objects that would be

seen through the spa cec raf t window before LO1 so that the range of acceptable attitudevariations could be studied. Such views would be valuable to the analys ts and to theflight crew because of the following reasons.1. The knowledge of whether stars or the lunar surface would be visible before,at, and during LO1 would provide cues for verification of attitude computations and ma-neuver progress . Attitude requ ireme nts a r e computed relat ive to stars, not relativeto the Moon; therefore, provision is made fo r proper attitude, even fo r an impro pertrajectory. Also, attitudes are determined by use of the optics, which ar e located inanother pa rt of the spacecra ft, and by sighting on objects differen t from those that arevisible through the spacecraft windows.2. Because of t erm ina tor movement ac ro ss the Moon during the monthly launchwindow, the surface of the Moon is not always visible at LO1 ignition.3. The LO1 maneuver is performed behind the Moon, in a heads-down attitude,with the spacecraf t gimbal angles referenced to another ine rtial attitude (with noobvious visible cor relat ion) . Mental visualization of the appearance of the lunarhorizon o r of stars through the spacecraft windows is difficult using this method ofattitude referencing.The first basic objective was achieved with the view program by generating thewindow view of the lunar hor izon at the Apollo 8 LO1 ignition time and attitude. Th isview demonstrated for the first time that the information available to the crewmen couldsupport an onboard go/no-go decision for LO1 simply by verifying that the lunar horizon,as viewed from the window, w a s near a refer ence ma rk on the window.In addition to the basic LO1 objective, it was recognized that attitude informationassociate d with tran slunar injection (TLI) w a s equally desira ble f or sim ilar reasons.Specifically, a method w a s sought to enable the crewmen to obtain information neededto support a go/no-go decision fo r TLI based on out-the-window determination of atti-tude relat ive to the crew optical alinement sight and the Ea rth horizon (or features).

2


8/19

This requirement w a s evident because multiple TLI ignition opportunities precludedground-dependent monitoring and evaluation techniques. Other complications that madesuch preflight window views des irable are the possibility of short time lines betweenorbit insertion and occurrence of darkness, the lack of assurance of spacecra ftplatform-realinement time, and the use of a launch reference stable member matrix(RE FSMMAT) concept (spacecraft-attitude indicators re ferenced to inert ial conditionsat launch with no physical meaning to the crewmen).Program Description

The view program operates on the UNIVAC 1108 computer. The program is writ-ten in the FORTRAN V language, which can be converted eas ily to operate on other com-puter systems. The program consi sts of two basic par ts: the integr ator portion andthe graphic-display portion. The integrator portion use s ei the r the Encke o r the Cowellintegration method and can integrate any nonpowered-flight tra jec tory after the initialstate vector is known. To generate graphic displays, the numerical data that describedthe display must be available ,from the in tegrator portion of the program. The graphicdata can be displayed at any nth value of the integration step.sists of microfilm fr am es produced by a cam era that photographs an image constructedon the surface of a cathode-ray tube.the segment desi red , lines and curves may be produced by connecting the dots.

The graphic display con-The image is formed by dots, and, depending on

Although the principal fo rm of output is microfilm frames, numerical data, aswe l l as crude printer-plo t images of the data, may be requested.and images are helpful because they provide fo r a quick-look evaluation before themicrofilm fr ame s are received.standard sheets of paper.

The numerical da taFor most uses, the microfilm fram es are printed on

The basic changes and modifications to the original program to achieve the desiredobjectives were associated with the input/output options, coordinate transformations,lunar - and solar -ephemeris installation, three -dimensional-display problems, and re -alistic spacecraft-window outlines. After the basic program objectives were identified,they were readily achieved or resolved. Additional mission applications then wer e de-termined to be feasible, and work w a s begun in this regard. A summary of the finallunar-mission view-program capabilities is provided in the appendix.development of the program capabilities, verif ication of accura te res ul ts w a s performedmanually.Throughout the

Program App I cat onsPreflight views produced for the Apollo 8 mission included views as see n throughthe spacecraft windows during various critical maneuvers of the flight. These maneu-

vers were at TLI, LOI, transear th insertion (TEI), and the ent ry phase. In addition,views of the Earth and the Moon as they would appear from the spacecraft at varioustimes during the mission were provided. Topographical features, such as outlines ofcontinents on the Earth and major craters, rilles, and seas on the Moon, were shown inall views. On both celest ial bodies, the terminator was shown with shading lines to in-dicate the darkened portions. The terminator w a s perpendicular to the subso lar point

3


9/19

through the center of the celesti al body. However, the Ea rth term ina tor could not beduplicated accura tely because of the atmospheric scattering of light.

fr om the command and serv ice module (CSM) when the lunar module (LM) w a s inthe docked configuration. The docked LM blocked a considerable portion of the viewthrough both the left and right rendezvous windows. However, the studies were indica-tive that, during LOI, se ve ra l lunar featu res could be observed through the rendezvouswindows and the hatch window.

For the Apollo 1 0 mission, a major question arose concerning the celestial view

J-40 Dabih Field of view = 100" -Altitude = 302 stat. mi.I 1 1 1 1 I 1 1 1 1 1 I I I I . I I I I I I 1 I I I I . I a l , , , , , , , , , l u . , -

As a result of data furnished for the Apollo 8 and Apollo 1 0 missions, theApollo 11 crewmembers reques ted cha rts of views that would be seen, during variousper iods of the mission , through the command module (CM) scanning telescope and theLM alinement optical telescope.navigation and fo r platform alinement. In addition to the cr iti ca l maneuver -attitude datafo r TLI (fig. l), LOI, TEI, and ent ry (fig. 2) , C M and LM optics views are shown infigures 3 and 4. The advantage afforded by charts such as these is the opportunity ofthe crewmen for preflight familiarization with the celestial sphere without being in theconfines of a cockpit simulator. Therefore , installation of CM and LM optic s geometryto accommodate alinement functions became part of the program capability.

These views w e r e used for preflight star selection fo r

Per hap s the most important application of t his program w a s the production of de-tailed preflight views fo r the cruci al lunar descent and landing phases. Such views werein demand immediately after use of the program in lunar refere nce w a s determined tobe feasible. The resu lts of thi s effort were promising, not only because of the unique-ness of these descent views, but because the Apollo 11 crewmen had elected to beginthe descent with the LM windows face down. In that attitude, the lunar ter ra in w a s

Figure 1. - View at TLI burn(Apollo 11).

50

40

20

1 ltairNun'ki '

1eacock

Figure 2. - View at entry phase(Apollo 11).4


10/19

40:

20:

E := 0:>-

-20

Oiphda1 1 1 1 l l l Ll I 1 L L I I I 1 1 1

-50 -40 -20 0 20 4 0 5 0-@[; , , , , , ,

5 0 1 1 * 1 ! 1 I I I I I I I I 1 I I I I I 1 1 I T T T I I I I I P I I I I I I I 1 1 I , , -:S i r ius-

e . iCapella- . * i. +VenusAldebaran -45 .-40 Mir fak-35-30

-20 .-15-10-5Earthoo

i

I I * I I l t t t t l ISaturn

Alpheratz

Rigel

Menkar

:-

X. deg

(a) At 124:40:00 hours ground e lapsedtime.Gimbal angles

40iAltair

Dabih

-45'iNunki -40. . -35Ra sal hagu etria -20.

. -15'i 10 .

- 5ntares**. .i:Alpheratz:-

Menkent40 .~ l * , ~ ~ ~ ~ ~ ~ ~ l - l ~ . , , , , l . .1 a L , , . i , . , . , . . . l . . . , :

-50 -40 -20 0 20 40 50

Gimbal anglesI = 17.86'M = 0.0'

iFomalhaut +Enif

(b) At 125:OO:OO hours ground elapsedtime.

X. d q (a) Front detent position.

time. optical telescope (Apollo 11).(c) At 125:15:00 hours ground elapsed

Figure 3. - Views through the scanningtelescope (Apollo 11).Figure 4. - Views through the alinement

5


11/19

*Saturn*P - enkai-3. 0:> .

+*-. .-

us-

* :* ProcyonAldebaran *-40- Venus - -

0Earth

I , L I I * . I I . . . L I * I & 1 1 I I L--50 -40 -20 0 20 40 50X. d q

(b) Left front detent position. ( c ) Left r ea r detent position.

-* :Alpheratz :-..-* -Saturn 3

(d) Rear detent position. (e ) Right rear detent position.Figure 4. - Continued.

6


12/19

40:

20:

P 0>--20

-40

-50

0 0 0am,,,,,,,,,,

5 o L o ~ s ~ II I I I O , , , I * I I I I , T " ' T " ' I I I I I I I , I I I 1 6 1 1 _ visible, and the view of the te rr ai n could beused to evaluate ignition-time e r r o r s andburn progress. Subsequently, the LM wasyawed in the di rect ion of the Earth to aforward-facing direction fo r final descent. and landing. Photographs of the lunar su r -face near Apollo landing site 2 were used toproduce two-dimensional cr at er models thatwere installed in the program. The engi-neering drawings of the left, right, andr - overhead LM windows, with the appropriatesc ribe marks , wer e obtained.drawings, the window outlines, as we l l as

: - the lunar landing-point designator (LPD) andoverhead docking scribe, were incorporated

-Earthr -Saturn L

-I

0 :

Mirfak I From these

Polaris...,, . . I , , . . . . l l l . l ~ * , . r ~ l , l . r . . , , , I I , , I , I S I I-40 -20 0 - 20

(a) Front windows. (b) Docking window.Figure 5. - Views during the descent phase (Apollo 11).

40' ' ' M

7

into the view program. These windows and


13/19

Typical views of the Ea rth and Moon during translunar coas t are shown in fig-u r e s 6 and 7 (R = altitude above the Earth, nautical miles ; Vi = ine rtia l velocity, fps;hE = altitude above the Earth, statute miles; and hM = altitude above the Moon, sta tut emiles). This program application ha s been used i n preflight and postflight photographicplanning and evaluation. Also, these views were useful for crewmember orientationduring television tra nsmis sions from space.

E

Another importan t use was made of the program capabilities to aid in determiningi f sufficient landmarks were visible for candidate landing sites to allow the crewmen toorien t themselves and land at a precise lunar location within 4 minutes. Because thelunar landing is performed in a parti cular attitude time line, the lunar surface is notvisible until only 4 minutes of fuel remain. Therefore , the key is su e was to determinehow various landmarks appear in the LM window field of view during the last 4 minutes.

R E - 101 519 n. mi .V: - 5446 fps

IR = 104623 n. mi.Vi = 5321 fps

hE 112 862 stat. mi. EV; = 3713 mph .

hE 116 434 stat. mi .Vi = 3628 mph

X. nondimensional(a) At 23 hour s ground elapsed time. (b) At 24 hours ground elapsed time.

Figure 6. - Ear th views during translunar coas t (Apollo 11).

8


14/19

RE = 107 659 n. mi.vi 5 5203 fps hE = 119928 stat. mi. R~ = 110 629 n. mi.Vi = 3547 mph vi - 5571 fps hE = 123 345 stat. mi.Vi = 3471 mphL

-m5I

>-:

._"7c

.-u --c .

X. nondimensional X. nondimensional(d) At 26 hours ground elapsed time.- _c) At 25 hours ground elapsed time.

Figure 6. - Concluded.Spacecraft relative to MoonhM = 20 876 stat. mi. Spacecraft relati ve to MoonhM = 15 593 stat. mi.

Vi 3927 fpS - 2677 mph Field of view = ha

(a) At 70 hours ground elapsed time. (b) At 72 hours ground elapsed time.Figure 7. - Moon views during translunar coast (Apollo 11).

9


15/19

To give a better resolution of the viewthrough the left fron t window of the L M andto prevent the fisheye effect, the field ofview w a s decreased arbitrarily. A typicalview of a candidate site (Rima Prinz) isshown in fig ure 8. Only the left front win-dow is shown because it had the LPD, withwhich the horizon movement is measuredaccurately. At the particular time shown,the iunar horizon is on the 58" reading ofthe LPD. Several surface featu res, includ-ing rilles and craters. are visible.

Enif Fomalhaut

-30-40

Diphda

In the application of the program tothe ApoPlo 13 contingency, not only werewindow-view descriptions relayed to thecrewmen for the abort burn, but the viewsof the Earth were used as the sole attitude-reference source for a midcourse correc-tion. Because normally the burn attitude isestablished by the use of an elaborate guid-ance and navigation sys tem (unavailable be-cause of power limita tions), the us e of theEarth horizon and terminator w a s signifi-cantly different fro m normal operations. Apreflight view of an Apollo 13 abor t maneu-ver (typical of those published fo r contingen-cy planning to demonstrate the feasibility ofsuch nonnominal opera tions) is shown in fig-ure 9. Fortunately, the program had beendeveloped and confidence had been estab-lished so that the program could be usedduring the Apollo 13 mission at the timewhen it w a s needed.

In addition to the applications men-tioned, many othe r use s have been made ofthis program. Data generated for the Apollomissions have been used by the cockpit sim-ulator personnel in checking or augmentingthe flight-crew simulators. Because thesimulators did not have some of the celes -tia rbo die s (planets, Sun, and, in somecases, the Earth) displayed, the view pro -gram was a valuable addition in this area.Also, a considerable portion of the preflightviews prepared fo r each flight has been in-corporated into the Apollo flight-plan docu-ments. These views and othe rs are of

-50 -40 -30 -20 -10 0 10 20 M 40 M

Figure 8. - View of Rima Prinz(candidate site).

Nunki

Peacock

J

considerable help to the ground-control personnel in visualizing what the crewmen areseeing, o r could see, eithe r through the windows o r through the optical instruments.

10


16/19

CONCLUDING R EM A R K SAlthough there were no requi rement s fo r spacecraft-window views of the ce les tia lsphere during a lunar mission before the Apollo 8 flight, the recognition and develop-ment of such a computerized capability have proven to be valuable in the support of allsubsequent Apollo missions. Specific mission requirements that were developed andfulfilled by the u.ce of th is computer program and a preflight report include the following.1. Crewmember and ground-control-personnel amiliarization2. Backup attitude checks for all major thrust maneuvers3. Preflight star selection for navigation and for platform alinement4. Confirmation of t rajectory progre ss during lunar descent and ascent throughobserved crater movement across the landing-point designator5 . Landmark identificationAlthough the program capabilities were developed and applied primarily forApollo-related tasks , the capabilities a r e not limited to lunar missions. New require-ments and applications presently a r e being formulated for future NASA programs.of these objectives will be achieved by use of the current computer program; other ob-jectives will necessitate additional development. In either case, based on Apollo expe-rience, this effort will continue to be valuable f or planning and for actual space flights.In any future endeavor involving man in space in which success and safety dependon man's understanding of his relationship to his surroundings, a computerized program

of the type described in this report should prove valuable both as an analytical methodand as a means of augmenting the training of both monitoring personne l and crewmen.

Some

Manned Spacecraft CenterNational Aeronautics and Space AdministrationHouston, Texas, January 29, 1972924 22 -20 11-72

11


17/19

A P P E N D I XL U N A R - M I SS I ON V I E W - P R O G R AM C A P A B LI T I ES

Many new capabilitie s were added to the view program to suppor t the initia l Apollolunar-landing mission as well as subsequent missions .view program are as follows. The major capabilities of the

1. As many as four vehicle tra jec tor ies can be integra ted simultaneously. Thiscapability is useful during rendezvous or after separation of the LM and the CSM or theCSM/LM and S-IVB vehicles. By integrating two tra jec tor ies and by using the graphic-display capability, a determination can be made whether or not the secondary vehicle isvisible through a window of the optical system of the primary vehicle.2. Command module and LM windows and optics outlines can be simulated. Thesi ze, look angles, and exact body-coordinate location of the windows are obtained fromdetailed engineering drawings of the spacecraft. The CM- and LM-window outlines are

fo r the ast ronaut 's design eye position. However, if the astronaut were to move fromthe design eye position, the outlines would change. Objects in a specif ied field of view,but not necessarily within the window outlines, are shown. This la rg er field of view isshown so that the obs erver can identify a star pattern, although pa rt of the pattern isnot visible through the window at the time the view is seen.3 . The us er h as the option of using two star catalogs. The one more often usedconsists of the 391 stars used by the Apollo crewmen for navigational sightings.first 3 7 stars are the prime Apollo navigational stars and ar e identified by name on themicrofilm.tains 1078 star listings, ranging in visual magnitude to 4.5. None of these stars isidentified by name, but all appear as dots on the microfilm,

TheThe remaining stars a r e represented by aste risks . The other catalog con-

4. A true perspective of the lunar te rrain during the descent maneuver is pro-vided, A s the descent is simulated, circular cr at er s appear as ellipses from certainspacecraft attitudes.5 . Major topographical features of the Ear th and the Moon a r e indicated.6. The vehicle outlines of the CSM, LM, and the S-IVB an be drawn. The appar-ent si ze of the vehicles wi l l be shown when viewed from a different vehicle.7 . Hidden-line models of the LM and the S-IVB an be produced; that is , given a'cert ain spacecra ft attitude, only the portion of the spacec raft visible to the obse rverwill be shown.8. A planetary ephemeris , which gives the position of the Sun and the Moon withrespe ct to the Earth, is produced.To use any o r all of the capabilities listed, the vehicle position, velocity, and atti-tude and Greenwich mean time must be known, These data a r e obtained readily from theoperational traj ectory document, which is printed and available seve ra l months beforeeach Apollo mission.

12


18/19

The coordinate systems that are available to the use r are the Earth-fixed system,the Earth-centered ine rti al system, the selenographic system, and the body-axis s ys -tem. The us er has the option of using an inert ially fixed platform or a local-verticalplatform.

--Langley, 1972- 1 S-323 13


19/19

11111111111111 II 11111111lllIlII IN A T I O N A L A E R O N A U T I C S A N D S P A C E A D M I S T R A T I O N

W A S H I N G T O N . D.C. 20546 P O S TAG E AND FE E S P A I DOFF C I AL B U S N E S S

P E NALTY FO R P RI V ATE USE $300NATI O NAL AE RO NAUTI CS ANDFIRST CLASS MAIL S P ACE ADM I N I S TRATI O N

NASA 451

POSTMASTER: If Undeliverable (Section 158Postal Manual) Do Not Return

"The aeronautical and space activities of the Unite& States shall becondzxted so as t o contribute . , . to the expansion of hum an knowl-edge of phenomena in the atnlosphere and space. T h e Administrationshall provide for the widest practicable and appropriate disseminationof inforntation concerning its actiilities and the results thereof."

-NATIONALAERONAUTICSN D SPACE ACT OF 1958

NASA SCIENTIFIC AND TECHNICAL PUBLICATIONSTECHNICAL REPORTS: Scientific andtechnical information considered important,complete, and a lastingcontribution to existingknowledge.TECHNICAL NOTES: Information .less broadin scope but nevertheless of importance as acontribution to existing knowledge.TECHNICAL MEMORANDUMS:Information receiving limited distributionbecause of preliminary data, security classifica-tion. or other reasons.

CONTRACTOR REPORTS: Scientific andtechnical information generated under a NASAcontract or grant and considered an importantcontribution to existing knowledge.

TECHNICAL TRANSLATIONS: Informationpublished in a foreign language consideredto merit NASA distribution in English.SPECIAL PUBLICATIONS: Informationderived from or of value to NASA activities.Publications include conference pr,meedings,monographs, data compilations, handbooks,sourcebooks, and special bibliographies.TECHNOLOGY UTILIZATIONPUBLICATIONS: Information on technologyused by NASA that may be of particularinterest in commercial and other non-aerospaceapplications. Publications include Tech Briefs,Technology Utilization Reports andTechnology Surveys.

Details on the availability of these publications may be obtained from:SCIENTIF IC AND TECHNICAL INFORMATION OFFICE

NATIONAL AERONAUTICS AND SPACE ADMINISTRATIONWashington, D.C. PO546

apollo experience report the application of a computerized visualization capability to lunar...

Documents