surveyor 1 a preliminary report

8/8/2019 Surveyor 1 a Preliminary Report

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.. N 6 6 29481< 3/

(NASA C R O R TM X O R AD N U M B E R ) (CATEGORY)

S U R V E Y O R IA Prel iminary Report

NASA SP-126

N A T I O N A L A E RO N AU TIC S A N D SPACE A D M I N I S T R A T I O N


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I.

Cover Photo: Surveyor 1 's survey television cameraphotographs i t s own shadow on thelunar surface. Picture was ma de latein the lunar af ternoon (June 12 , 1966,a t 1 0 : 5 8 : 2 8 G.m.t .1 , a f ter the per iodcovere d in this pre l iminary report .


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NASA SP-E6

S U R V E Y O R IA P rel im inary Report

Compiled byLunar and Planetary Programs DivisionOffice of Space Science and Applications

Scientific and Technical lnf ormation Dizision J U N E 1 9 6 6NATIONAL AERONAUTICS AND SPACE ADMINISTRATIONWashington, D.C.1 5 4


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This document is avai lab le from the Clearinghouse for Fed era l Scienti f ic an d Technical Information (CFSTI),Springfield, Virginia 2 2 1 5 1 , for 7 5 cents.


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SUMMARYTHESURVEYO R 1 S P A C E C R A I T W U S ~all1lChed 11

M a y 30, 1966, from Cope Ken nedy , Florida, on (1direct-ascent lunar trujcctory. Approximutehi 16hours after launch , u successful inidcourse correc-tion maneuver was executetl, moving the landingpoint some 35miles to a n area north of the craterFlanisteetl in Oceanus Procellarum. Because te-lemetry indicated tha t one of th e tw o omnitlirec-tioital antennas may not have fully deployed, aterminal maneuver w a s used which assured cor-rect Earthward orienta tion of th e d ep l o yed an -tenna during descent. The spacecraft properlyexecuted all comm ands, and th e automatic closetl-loop descent sequence was completed at 06 17 36GMT on June 2, 1966. Preliminary data retluc-tion indicates that the spacecraft touched downut a vertical velocity of appro ximateh i 10 f i ls ut2.41 S . lat. and 43.34" W long.Durin g its first five day s of opera tion on th eAloon, Surveyor 1 transmitted more thun 4000pictures. Following are the preliminary findings11y the Surveyor Scientific Evaluation and Anal-ysis Tea m and associated working groups on thescientific data received up to tha t t ime:Surveyor 1 landed on a dark, relatively sniooth,bare surface, encircled by hills and low nioun-tains. Th e crestlines of a fe w of these low moun-tains are visible along the horizon, from whichthe spacecraft may be located accuratehi withrespect to / l ie major features o f the lunar surfuce.0l)se rvat ions of Sirius anrl Cano pus and titimer-ous points o n the horizon s h o i ~liut the land ingsite is sniootli and nearly level on a kilometerscale.Tlic tcrruiii within 1 to 2 kin siirrounding theSiiroeyor I luntling site is a gently rolling stirfucc

stiitltlctl with craters with tlianictcrs from a fezc;centimeters to scvcral hvndreil meters and lit-tered with fragmental debri s runging in sizefrom less thun 1 nini to more than 1 ni. Thel a r g o cruters observed resemble those seen inthe Rnnger photographs in shcipe und clistribu-tion. Thirs tlie Siiroeyor I lnntliiig site uppearsto be a representative sample of a marc surface.T he srirface is coniliosed of granular materialof ci wide size range; course blocks of rock untl.snir~llerrugnients are set in a matrix of fine par-ticles too s i n d l to be resolved. Th is material w u stlistrirberl anrl penetrated l q the foot p a d s of thespacecraft i o (i t l ep ih of u few ccntinieters. Thets7iapc" of s1nall craters suggest that the frug-Incntal h j c r I l l U ! j extent1 t o c1c)itlls of fit least(1 1netcr.

The mutcrial tlistrirbetl l q he spucecraft foot-p a d s is made r i p of l i m p s that are probahlyaggregutes of nirich finer grains, 1 nini or less i ndiameter. These aggregates show that the frag-mental muterial on th e local lrrnur surface is atleast slightly cohesioe. Some tlistiirl~etlmaterialt ~ a shrown oiit to form m j s , similar in shapeanrl apparent genesis to those observed fromEurth around sonic large cwitcrs, b t i t (lurker tha ntlic udljacent cstirfuce.

I f tlic muterial is honiogcncoiis to a depth 01some ten s of centimeters, th e soil appears to have(I *stuticbcuring capticit!j, on thi s scule, of abou t5 lisi (3 x 10; d! jnes /cn i2) .

Thcrmul datu, ( I F s1ioic;n b ! j ( I conipnrison ofpredicted untl uctriul spacecraft temperatures, in-dicate t h a t tlie spucecraft tcinperatrrre-controlqstrrfucc>sir e not covered b! l (lust.


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c

. . . a h r c surjfacc, cwcirclcd h y hills a i ~ dow mountains.

SURV EY0 R I A Pre l im inary ReportINTRODUCTION

Is V S X ~ S N E D LUSAR EXPLORATIOS, the Sa-tional =\eronautics an d Space Aclniinistration isciirrently conducting t\vo programs, Smveyorand Liinar Orbiter. The latter is planned to pro-vide medium- an d high-resolution photographsover broad areas to aid in site selection for the.1po110 manned-landing program. The Surveyorprogram lias three major objectives. One is tod i d a t e sevcrnl critical aspects of advancedsoft-landing techniques for later use by Apollo.-1notlicr is to pro\-ide essential data o n the com-patibilitp of tlie -1pollo design \\it11 conditionsencountered 011 the lunar surface. A third is tod t l to scientific knowledge about the Xloon.

Th e first Surveyors have been planned t o provethe design of the spacecraft, develop the criticalsoft-landing teclmiquc, and to acqiiire liinar-surface information needed for later Sur\reyoran d =\pollo missions. Subsequent spacecraft i ntlic series \\ill, in addition. conduct operationscalcnlatecl to siippI!- additionill scientific infor-mation alxmt the )loon a n d the environnient atits surface.

Surveyor I , the spacecraft described lierr. \vas

the first engineering test model to be flown.Though it did not carry scientific experiments,i t was fitted 11-ith a survey television system and11ith instrrimentation intended to measure bear-ing strength, temperatures, and radar reflectivig-of tlie lunar surface.

The Suneyor program is being conductedwider the direction of S-ASAs Office of SpaceScience and Applications, with the Je t Propiil-sion Laboratory providing project management.The Hughes -4ircraft Company has responsibilityfor the design and fabrication of the spacecraft.

Prior Scientific DataThe firqt pictiires of th e Sfoon taken from 1

spacecr


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down to almost 1 foot. Prior to Surveyor I, thepictures of the lunar surface having the bestresolution were obtained on February 3, 1966,by Luna IX , showing details of the surface do\vnto fractions of a n inch in tlie iininediate vicinityof tlie landed caps&. Luna 1X w a s reportecl toweigh 3450 pounds (1578 k g ) at separation frointhe launch \-chicle, and tlic laiiding capsule wassaid to wcigli 720 poiinds ( 100 kg ). Surveyor Iweiglied 2194 poiincls ( kg ) at sepxationand 5% poiinds (270 kg) at landing.Liina IX provided pliotograplis slion7ing thesurface testiire a t one location o n th e h4oo11.Sonic infcrences as to tlic load-bearing qiialityo f the surface may be derived from the fact thatthe capsdle did not sink below tlie surface. Anumber of important Surveyor I mission objec-tives, howe\-er, were not met l y the muclisimpler L,una IS. lhesc inchidc:

Verification of dvancctl closcd-loop sof t -landing tcc1iniqiic.s similar to those that ivi l l I)c,u s c d to I:1ntl mcn o n thc ; \ loon;

Quantitative data on siirfacc Iwnrings rc.11g 11;

Qriantitati\x> (lata on r x l a r reflcytivity;Qunntitati\.c. data o n Irin:ir-srirfacc tcmpcra-

tllrc rangs; a n t l

terminal maneuvers, and to acIiic\re a soft lnncl-ing on the Xioon;

Ilemonstrate t he capability of tlic Surveyorcoininunications system aiid I>ecp S p c e Net-work to 1nain ain communications wit11 thespiicccraft during its flight a n d after a soft land-ing; and

Ihnonstratc tlie capalility o f the Atlas!Centaur larinch vcliicle to injrct t lw Surveyorspicecraft o n a liinar-intcrccpt trajectory.

S e c o n d a r y O b j e c t i v e sObtain in-flight engineering data on all

spacecraft srihsystems used in cruise flight;Obtain in-flight engineering data o n al l sub-

systems INYI dllring tlie midcourse niaiicuvc~r;Obtain in-flight c~iiginecring lnta on tlic pe r -forn iancc~ of tlie closctl-loop tcrininal dcwwit

giiitlance an d control systcm, including the \d oc -ity antl nltitiid(. rathrs, tliv on-l)oart l analog com-p I ter, t ic, :i 1topi lot , and t1 c w r n ivr cn invs : ;ind

Ol,tain cngiii(~riiig&ita on tlicx perforlnnnceo f sl l l~s~~stc~mss c d o n thc I11nar sllrfacc,.

T e r t i a r y O b j e c t i v e sA detcriiiiixition iis to \vlietlicr or not thcw 0l)tain postlanding TV pictrues of a S ~ X W -

craft footpiid :uid t l i r siirfacc. material immcd-Litcl!. surroiintling it ;

O1)tain posttlantling T\ pictrircs of tlrc lrinarObtain (lata on tlic r x l a r rc4wtivity of the

is loose dust o n the l l o o n .

Surveyor I Mission Object ives topogrqlliy;IIc+ailetl planning go;ils fo r this flight \\XYX

P r i m a r y O b j e c t i v e s


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VEHICLE DESCRlPTlON

THE P.XE VEHICLE FO R THIS >rIssIos consistedof an Atlas-Centaur Iaiincli \-chicle, Surveyorspiicecraft. adapters bet\vcwi the launch-\~eliiclestages and bet\\.een tlie Centaur and the spitcc-craft, and ;I clamshell-shaperl fairing that en-closed the spacecraft diiring atmospheric flight.Figure 1 sl io\~slie veliicle during laiinch fromComp1e-i 36--1 t Ca1w Kenned!..

Launch VehicleTlic r\tlns-Centnur AC-10. the launch \.chicle

fo r Sur\-e) r I. \\ 'as a t :~ct-s tagc \&ic-le: tlwA\tlas first stage \vas ixnvered b y tlicl stmdardSI.1-5 propiilsion system Iinving t\vo booster en-gines and a sustaiiicr engine; tlie Centaur secoliclstage \LIS po\\-ered b y tu o high-energy RL-10cngines. cacli \\,it11 13 000 pounds of thrust. Tlwpcrformaiice chnracteristics and dimensions oftlw launch vc4iiclc arc slio\\.n in figi i~, .

The RL-IO eiiginc i s the first engine to operittc,ftilly in splc? wing l iquid hy dr o pi as a

fuel (,liquidoxygc v is used its thc, oxidizer ). TheCentaur \\.as surroiindcd b y f o u r thermal insula-tion paiic~ls o mininiiz t~ he boil-off of hydrogen.\\-I1 ich \VAS main t ti ncd at a t einpera t ir e of-42.3' F. The panels were jettisoned after t hwliicle left tht atmosplierc.

The nose fairing. cons tructed of honepcombfiber glass. enclosed th r spacecraft and guidanceand electronics cqtiiliiiimt mounted on th e Cen-tatir. The fairing prmided thermal and aero-cl!-namic protection during flight through tlieiitmospliere and \T X jettisoned shortly after theinsnlation ii:tnels. I n addition to the primarypropulsion s!.stcm. the Centaur \\-as equipped\\.it11 small h!-drogen peroxide attitude-controltlirustcrs a n d four 5O-pound ( ???-ne\vton ) hy-drogen peroxide thriisters. The larger thriisttrs\wre used chiring tht, retromaneu\-er tha t \IXSpcrfornietl after the second stage separated fromt l i e spacecraft. This manetn-er altered the Ccn-

FIC:I.HE1.- Thr .\tias C(*rttatlr laiiiicli \ c . h i c l ~ . l i f t 5S u r w y o r 1 from Complex 36-A at CapeR(miier1y. F l n r i d ; ~ , 11 \lay 30, 1966.

taur's trajectory sofficiently to keep tlie Sur\Tey-or's star sensor from mistaking the second stagefor Canopus, and also to keep the Centaur fromimpacting the \loon.

SpacecraftThe configtiration of the Sur\-eyor spacecraft

is slio\\-n i n figtirc 3. The basic structure, whichpro\-itles moiinting surfaces nnd attacllments forthe povw. coniiii~inicatioi~s.ropiilsion, and flightcontrol s!.stems, as \!.ell a s ;I platform for tlwpii>-Io;idpackages. is constructcd of thin-\ralledaluminitm tuliing \\,it11 the mtmbers intercon-nected to form a triangle. A shock-absorbingImding leg is attachcd by a hinge to each of thetlirec lo\\.er corners of the structure. The legs

3


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4 S URVE YOR I : .I P R E L I l I I S . I R Y REPORTCLAMSHELL"'DAPTER7 f$:s, NOSE FAIRINGATLAS LV-3C .

P13 I -USTAINERSTAGE I ATLAS LV-3C CENTAURF I G C I ~ E

BURN TIME (SEC.) I 239 I 430 II 30LENGTH (FT.) I 61.6 I

~I 16.5AX . DIAMETER (FT.) I(WITH INTER- (WITH PAYLOADSTAGE ADAPTER) ADAPTER)AUN CH WT. (LB.) * 263 500 37 500

IURNOUT WT. (LB.) I (SUSTAINERONLY)7wo I* EXCLUDES SPACECRAFT

2. - Char;ictc*ristics of t h c s 1;iuneli \ - c ~ h i c l c ~ i x dor Sur veyor I .

\\'ere folded into tlie nose fairing du~ I i i g anncli.As additional protection against landing loads,blocks of crushable aluminiim honeycomb a r cplaccd on tlie bottom of e x l i corner of theframe. A vertical i n a s \v i t i iiiech anisins thatposition the Iiigli-gain planar array antenna andsolar panel is mounted on top of the structiire.The basic frame \veighs less tlian 60 poiincls ( 2 7kg ) and the installiition liarcl\\~nrc \vciglis 23

The spacecraft is sonic~10 feet ( 3 in) Iiigli,and its tripod landing gear fits just \vitliin ;i 13-foot (hi)ircle. If 'cigli ing 21LJ-i pomds ($195kg ) at launcli, Sur\veyor I had a landing \\.ciglitof 596 pounds (270 kg), after tlcyletion of pro-pe1l:unts antl other consrimablcs and aftcr jvttisoiiof thc ~Iltit~idc -niarki i~gx l a r antl the main rvtro-rockct casing.

T\vo thermally controllcd comp;irtnients, tlicirteiiipcwtiircs hcltl \\itliin iiccrptahlc limits 1)y acarcfii l arrangemcmt of nl>sorpti\rc i intl rc.ficcti\~cp i n t s , b y contlucti\~c. hcat p a t h m d tlicrmalwitchrs, and, on tlw dark sick, b y small electricIwitcrs, arc 1)rmidetl a l m i r d tlie spncccraft. Onecompartment, held lwt\{.een 40" F. an d 125" F.,houses coinm~micatioiisand most po\ver-supply

po"nds ( 10 k g ) .

electronics. The other, held Iiet\vecn Oo F. antl1.7,Fj0F., Iiouses the coininnid an d signal proeess-ing functions. The solar panel, consisting of aseries-parallel a r ray of 79.7 solar-cell modulesapprosiniiating 9 square feet in area, supplied Lipto 55 \vatts of po\ver during cruisc an d on th elunar siuface. Rechargcable sib-er-zinc batteriesare used for energy storage an d to accommodatep i k oads. A po\\'er-managcineiit system aboardl ias tlic, function of coinvrting, rcyyilating, an ds\i.itcliing p o \ \ ~ ris rcquired b y various siibsys-tcms.

Inertial rc,fcrcmces for detecting and control-ling t l ic , atti tudr of tlie spacecraf t during cruiseflight, a s \vel1 a s during niitlcourse und terminaln i a n c i i \ w s , \\.ere' pro\itlcd by a Canopis s t a rtrackcr, a S u n s ens o r , ;ind rate gyros on three~ I W S . Ihring cruise flight attitude control \vasc.\.crciscd by a subsystem employing siiinll cold-gas tlirristcrs. Control di i r ing tcwiiinnl tlcsccnt\\':IS c.sc,rciscyI initially 1)y tlir aiitopilot, vcrnicrcwgiiws, antl 1)y ;in altitutlr-marking radar thatI ~ g a nlica firing of the main retrorockc>t. Sitbsc-qucntly tlic spacecraft \vas stcwcd a n d dcceler-iitcd b y \,clocity-ineasuring a nd altimeter radarsthat, in conjnnction \\lit11 the on-lmard analog


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SLXVEYOR I: A PRELI3fISARS REPORT 5

FIGURE3.- Xlajor components of the Suneyor I spacecraft


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6 SURVEYOR I: A PRELI MI NARY REPORT

MIRROR ASSEMBLY

ZMVTH DRMGEARBEAM SPLITTERDRW MOTOR GEAR

ING CLAMP BANDFOCAL PLANE SHUl-fERWRIABl-E LENS ASSEMBLY

CONNECTORSVIDICON YOKE ASSEMBLY

FICUHE4. - Cutaway view.s of the survey television camera.

computer, autopilot, and vernier engines, pro-vided automatic closed-loop guidance for finaldescent to touclidown.

Two propiilsion systems were used by Sur-veyor I. Th e main retrorocket employed a solidpropellant in a spherical steel case. Its thrustw as o f the order of 8000 to 10OOO pounds (3 5 ,500to 14500 newtons), depending upon temperature.The second, or vernier, propiilsion system usedhypergolic liquid propellants. Th e fuel was mono-methyl hydrazine hydrate and tlie oxidizer wasMON-10 (90 percent NzOl, 10 percent N O ) .Three throttleable thrust chambers were used,each capable of de livering from 30 to 104 pounds(133 to 462 newtons) of thrust as required bythe flight-control subsystem. One chamber could

be swivelled for roll control. The vernier engineswere used for the midcourse maneuver and inthe terminal lunar landing sequence.

For communications, Surveyor I carries twotransmitters, two receivers, two omnidirectionalantennas, and the planar-array high-gain antenna,used for transmission of tlie 600-line televisionpictures. Tracking and engineering data weretransmitted continuously on a freqtiency of9295 Mc at a power of 10 watts. The radio linkalso incorporates decoders that address com-mands received from Earth to the proper sub-systems aboard the spacecraft, and signalprocessors that condition various data signalsfor transmission back to Earth.

The survey TV camera aboard the spacecraft


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SL?R\'ETOR I: .% PRELI1\IINARY REPORT 7(fig. 4 ) transmits 200- and 600-line pictures ofthe lunar surface on command from Earth. Thevidicon tube and its shutter, diaphragm, andoptics are mounted nearly vertically, surniountedby a mirror that can be adjusted by steppingmotors both in azimuth and elevation. Provisionis also made for remotely inserting filters in theoptical system, to permit colorimetric evaluationof individual pictures. The focal-plane shutter ofthe camera, normally providing an exposure timeof 150 milliseconds, can also be held open forlonger intervals on Earth command. A lens ofvariable focal length is used, covering a field of6.4" by 6.4" at its maximum focal length of 3.9

inch (100 mm), and a field of 25.4" y 25.4" inits wide-angle focal length of 0.9s inch ( 2 5 mm ) .The focus distance of the lens can also be com-manded to cover the range from 4 eet to i d n -ity; and the diaphragm, though adjusted auto-matically, can also be set by command sent tothe camera from Earth.In addition, more than 100 items of engineer-ing instrumentation were camed by Surveyor Iand their readings telemetered to Earth. Theyinclude temperature sensors, strain gages, accel-erometers, and position-indicating devices. Theneigli t of this engineering payload. including anauxiliary battery, is 63.5 pounds (48.5 kg).


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TRAJECTORYSURVEYORWAS LAUNCHED ON MAY 30, 1966,

from Complex 36-A of the Eastern Test Range.Its azimuth was 102.3O. The spacecraft wasinjected directly into its initial trajectory withoutthe use of a parking orbit. A midcourse correc-tion maneuver (fig. 5 ) was executed some 16hours after launch (06 45 GMT, May 31) andthe spacecraft was then returned to cruise mode.The autopilot and vernier propulsion system wereused for this correction, which called for only amodest change in the predicted landing point.

As Surveyor I approached the Moon about 63hours after its launching, a command from theDeep Space Network Station at Goldstone, Cali-fornia, modified the spacecrafts attitude to alignthe main retrorocket thrust axis along the pathof flight (fig. 6 ) . At an altitude of 59.35 milesabove the Moons siirface, a signal from thealtitude-marking radar mounted within the nozzleof the main retrorocket occurred, and. 7 seconds

later ( a t an a ltitude of 46.75 miles and a space-craft velocity of 5839.87 mph) ignition took place,expelling this radar and initiating the 40-secondmain retrorocket burn. At the completion of thisburn and jettisoning of the empty rocket case,Surveyor I was close enough to the Moon toreceive an excellent return from its radar altim-eter and Doppler velocity sensors. Operating ina closed-loop mode, these signals were processedby the on-board computer and autopilot to con-trol the three vernier rocket engines, steeringand decelerating tlie spacecraft in a predeter-mined optimum descent profile. Finally, at analti tude of about 1 4 feet, the vernier engineswere cut off and Surveyor I dropped gcwtly tothe surface of the Moon at ;i speed of approxi-mately 10 fps. It landed at a position (fig. 7 )within about 9 miles (15 km) of the aimingpoint established at tlie time of the midcoursecorrection.

POSITION OF MOON AT IMPACTTOUCHDOWN

RETRO PHASE (INITIATEDAT NOMIN AL RANGE OFGOLDSTONE

LAUNCU

LAUNCHPRERETRD MA NEUVERS ANDOTHER OPERATIONS (NOMINALLY 30MINUTES BEFORE TOUCUDOWN) /

POSITION OFMOON AT LAU NCH

REACOUlSlTlON OF SUN ANDSTAR (IMMEDIATELY AFTERMIDCOURSE CORRECTION)

SEPARATION

SUN ACQUISITION(NOMINALLY C I HOURAFTER AQUISITIONI 6 HOURS AFTER LAUNCH) AFTER LAUNCU )

F I GU I I E . -


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SURVEYOR I: A PREL13IIh-ARY REPORT 9

\\1\

PRE-IILRO MANEUVER 30 MIN.BEFOIIE TOUCHDOWN ALIGNSM A I N ETRO WITH RIGHT PATH\$

SURVEYOR TERMINAL DESCENTTO LUNAR SURFACEUppro~~iinokltitudesand Velocities Gwen)

MAIN RETRO START BY ALTFRAWM A R K I N G RADAR WHICH EJECTSFROM NOZZLE, CRAFT STABILIZEDBY VERNlER EN GINE S AT60 MI ALTITUDE, 6.100 MPH

I

MAIN RETUO BURNOUT AN D EJEC?".VERNlER RETRO SYSTEM TAKEOVER AT25.000 FT, 240 MPH

II

VERNIER ENGINES SHUTORAT 13 Ff, 3% MPtf

- -. .-.

FIGL-RE .- erminal descent and nominal events.


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10 SURVEYOR I: A PRELIMINARY REPORT

FIGURE.- Landing sitc of Surveyor I is some 35 miles north of the cra ter Flamsteed inOceaniis Procellarum. ( Photo from McDonald Observatory, Fort Davis, Texas. )


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TRACKING AND DATA ACQUISITIONDVRITGHE IMMEDL-\TE POSTLAUNCH PERIOD,

tracking and telemetry were accomplished b yEastern Test Range stations at Cape Kennedy,Grand Bahama, Grand Turk, Antigua, Ascension,and Pretoria. The ships Stcord Knot , COUSfdCrusader, and General Arnold also acquiredS-band telemetry- data. The NASA MannedSpaceflight Network provided support fromGrand Canary, Bermuda, Kano, Tananarive, andCarnarvon.

After the spacecraft separated from the launchvehicle, tracking and command functions for therest of the translunar trajectory were the respon-sibility of the Deep Space Xetn-ork ( D S X ) Sta-tions at Goldstone, California; Johannesburg,

South Africa; and Canberra, Australia. The mid-course and terminal maneuvers, and touchdownevents, were tracked and commanded fromGoldstone, which also served as the prime re-covery station for television data. All three DSNstations recorded flight data during periods ofspacecraft visibility from each station; and alltracking and telemetry data were sent to theSpace Flight Operations Facility (S FO F) at theJet Propulsion Laboratory in Pasadena, Cali-fornia, for reduction and analysis. The SFOFsemed as the focal point for the conduct of theSurveyor I mission and originated more than100OOO commands to the landed spacecraft.

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PRELIM1 NARY SCIENTlFIC RESULTS

Lunar Surface Mechanical PropertiesObservations and Explanations

THE NTERPRETATION of the lunar surface prop-erties discussed here is based on the photo-graphs showing the lunar surface area that wasand on the histories of the axial loads in thedisturbed by the footpads and crushable blocks, (a)- -shock absorber on each of the three legs duringthe landing (see fig. 3 ) . The important com-ponents of the landing-gear assembly are shownin figure 8, and their motions during landing areillustrated schematically in figure 9. The space-craft landed at a vertical velocity of approxi-mately 10 fps ( 3mps), with a small componentof velocity in the horizontal direction. At thepresent time, there is an uncertainty of severalfeet per second in all the velocity information.

Figure 10 shows the time records of the axialload as measured by a strain gage on each shockabsorber. It can be seen that surface contact forall three footpads was almost simultaneous, indi-cating that the spacecraft mast (fig. 3 ) at touch-down was approximately normal to the surface.The footpads impacted at intervals of 0.01 sec.Footpad 2 touched first, followed b y footpad 1and then by footpad 3.

The record further shows that following theprimary impact, the spacecraft rebounded clear

FIGURE 9. - Schematic of the Surveyor landing-legassembly showing the articulation in a se-quence of events during landing. I n ( a ) ,the assembly is fully extended. During alanding, the shock absorber compressesand the footpad moves up and away fromthe spaceframe, as shown in ( b ) . In ( c ) ,the assembly is shown reextended after.landing.

of the surface, and a secondary impact occurredapproximately 1.0 sec after the initial impact,indicating that the footpads rebounded about2% in. ( 6 cm ) above the surface. The secondimpact developed maximum loads equal to np-proximately one quarter of the maximum loadsdeveloped during the initial impact. The maxi-mum vertical load applied to the footpads bythe lunar surface material during the initial im-pact was 400 o 500 b, or 180 X 1V to 230 x lo6

STRAIN GAGEPHOTOMETRlC TARGET

CONTROL JET-STRENGTH 40 psi

FIGURE8.- Drawing of landing-leg assembly 2 .- w- --

c

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SURVEYOR I: A PRELIXZLXART REPORT 13

LEG 2I

FIGURE0.- Shock absorber strain-gage data 3%rcccivtd at C.ultl\toni., C;i!iforiiia. Notc thcoscillations follo\ving thr primary impact.

dynes ( 1 8 0 to 2200 newtons). Conversion ofthis load into a dynamic pressure applied to thesurface depends on the footpad area in contactwith the soil at tlie instant t he load is measured.Since the lower portion of the footpad is a trun-cated cone (see fig. S), this contact area dependsprimarily on the penetration clepth. Rased on themasimnm vertical load and the footpad areas: aunit loading of between 3 and 10 psi ( 3 x lo5and 7 x 1oj dynes/cni) w a s applied to thesurface during the dynamic stages of the impact.The static load required to support the space-craft on the three landing pads is about W psi( 3 x 101 dynes/cn?).Based on preliminary velocit). and spacecraftperformance data, analytical simnlations of thelanding dynamics have been performed. To date,for simulated landings on a rigid surface. forcelevels have been duplicated within 10 percent.IIov-ever, the timing of all r\-ents during thelanding a s indicated by th e strain-gage data . i.e..rise time of force, rebound, reimpact, and dura-tions of force during first and second impact, canbe duplicated a s precisely as tlie data al low itto be read out. The design of t he spacecraft land-ing gear is such that the forces and motions of

the spacecraft are largely independent of themechanical properties of the surface for surfacematerials whose static bearing capacity is greaterthan approximatel>- 5 psi ( 3 x 10 dynes/cm2).Further discrimination of the material propertiescan be obtained from analyses of the footpadpenetration.A number of oscillations with a masimnm peak-to-peak amplitude of several Iiundred poundsand a frequency near 7 cps are seen to followthe second impact (fig. 10). The oscillations ofthe forces in all the shock absorbers are in phaseand of about eqiial amplitude. indicating a recti-linear vertical mode. Th e frequency of the oscil-lations is related to the elasticity of the space-craft structure and tlie lunar surface material..Ipicture of a depression in the lunar surfnce

under cylindrical criishable hlock 3 ( see fig.11) indicates that it also matle contact with theIimar surface. At the dnte of this writing, it hasnot been possible to identify positi\.ely any lunarsurface depression under crushable hlock 1. Thearea beneath criishable block 2. and tlie crush-able blocks themscl~-es, annot be seen with theSurveyor TV cmncra. HoIvever. the s)-mnietry ofthe impact and the gcncrd local flatness of thc


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14 SURVEYOR I: A PRELIMINARY REPORT

lunar siirfacc Icwl to tlw concliision that :ill tlic.crushable blocks madr contact with the lunarsurfiicc. h4cnsnrc~mcnts f shatlows of tlw dqxes-sion rnadc by crusliablc block 3 indicate ;i c k -pression depth of about k in. ( 2 cm).

Pictures of each footpad confirm tlie naturcof the landing expressed by the dynamics data.

Pat1 2 (fig. 12) and pad 3 (fig. 13) ar c bothvisiblc; pad 1 is not. The appearancc of t he lunarsurface neiir pads 2 and 3 indicates similar be-havior of tlie material displaced by the two pads.They appear to have landed in a granular mate-rial, to have estencled laterally during impact (asshown in figlire g ) , forcing the surface material


21/46

t

- 15URVEYOR I : -4 P R E L I l f L K . i R Y REPORT

i

I~~~~~~ -

FI( .C-RE2.- Vitlc, -angle photograph of footpad 2. Sote the displaced mntcrial that c'ovcnthc l u n ar su r f ace I~cymcl he footpad, and the ray extending to t h e l e f t fromtlw footpad.

ana), and then to h e r m n back on the re-bo~incl o their final position, lec*\ ng a disturbedregion of the surfxe.There is no evidence to indicate crushing oftlie conical section of the footpad. &I t east the\isibIe part of the lower layer. m d e n p of al i i -miniim honeycomb material ha\ ing a crusliingstrength of 10 psi (7 x IOi d! ne\/cm2), is und'im-aged (s ee fig. 14). 50 rushing of the upperI+ er of crnshable structure (crus21ing strengthof 20 psi. or 1 x IO6 d)nes/cm') took pl'ice. It

should be noted that. at tlie landing ve1ocit)- ofapprozirnate1~- 0 f i x ( 3 m p s ) . preflight analyses1iaI.e sl io\~n hat no criisliing of tlie footpads\~-ouldccur e wn on a rigid surface. This wouldindicate that d!mamic pressures of 10psi (7 x 10'dynes cn? ) on the footpads during landing werenot esceeded and that t he footpad did not crush,h i t displacement of the griiniilar surface materialoccurred. The shock-absorber data. as discussedabove, are i n iipreement with this evaluation.both p x l s 2 and 3 there is a throwout pat-


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5


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18 SURVEYOR I: h PR EI,I \ I IS A R Y REPORT


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SLRVETOR I : .% PRELIllISARY REPORT 19

F I GU R E6.- Sarro\v-angle photograph of the tlisturlxd Iiiiiar surface material near footpad2 , The pail is in the upper portion of thr photograph; the surface h \ \ - n liesbet\veeii the footpad and the cpacrframc..

(fig. S ) \ \ -as operated after landing. This jet usescold nitrogen gas to produce a thrust of 0.06 lb.It n-as located approximately 6 in. (15 cm) froli1.and at an angle of 7 deg to. tlie surface. Pic-tures 1vei-e taken before, diiring. and after thefirings. \vliicli consisted of short pulses repeatedf u i periods tip tz 1.5 S P C . The duration of the

pilses \\-as 20 nisec witli a 30-msec pause be-tlveen pulses. -it the present time, results of thisexpc,riment are inconclusi\.e. since the initialstudy of thc pictures taken before and after tliefirings did not indicate a n y obvious soil dis-turbance. -imore detailed study of these picturesremains to be made.


26/46

20 SURVEYOR I: A PRE1,IhfINARY REPORTInterpretations

The appearance of the disturbed surface mate-rial and the rim of the impact depression suggestthat the surface is a granular soil-like medium ofunknown but fine grain size and size range. Onclisruption by the impact, some fine-grained ma-terial was thrown out in a spray, possibly froman original surface layer, and the underlying ma-terial was broken tip to some extent.

The behavior of the material is consistent withits possession of a distinct but small amount ofcohesion, and its manner of deformation appearsto be qualitatively similar to that which mightbe exhibited by a terrestrial, damp, fine-grainedsoil.

The appearance of the lunar surface and thenature a nd depths of the depressions formedduring landing are very similar a t pads 2 an d 3,so that, at least to the scale of Surveyor, the ma-terial properties appear to be horizontally homo-geneous.

If, to a depth of the order of the footpad diam-eter (1 t. or 30 cm), the material is homogene-ous and similar to that observed at the surface,a simplified landing dynamics analysis indicatesthat the soil has a static bearing capacity, at thescale of the Surveyor footpad, of about 5 psi( 3x l@ ynes/cm2).

Although this bearing capacity can be devel-oped by materials having a wide range of prop-erties, a reasonable choice, considering all theavailable data, is a soil with a cohesion in therange of 0.02 to 0.05 psi (1 x lo3 to 4 x 10dynes/cmz) and a friction angle between 30 and40 deg, at a density typical of terrestrial soil ( 3sliigs/ft3or 1.5 g/cm3).

IIowever, the landing dynamics data, penetra-tion observations, and landing simulations per-formed to date are also compatible with a liinarsurface consisting of a hard material ( static bear-ing capacity greater than 10 psi, or 7 x 1 0 lyncs/cm2) , overlain hy a weakcr matcxrial, to ;i depthof about 1 in. (25 mm).

Lunar Surface Thermal PropertiesEarth-Based Observations

TIIKLANDING SITE OF SURVEYOR, 2.4 S lati-tude and 43.3 \V longitude, is contained in the

Lunar Isothermal Chart (ref. 1 ) .The site is ina b la nd area, in that local surface temperaturegradients across the surface during lunar eclipseare small; this is typical of the major portion ofthe visible lunar surface. A further characteristicof these typical areas is that th e surface exhibits;i high value, of the order of 800 cgs units, of thethermal parameter ( k p c ) - % , where k is thermalconductivity, p is density, and c is specific heat.For comparison purposes, an evacuated powderconsisting of 1- to 25-p-sized particles of olivine,tektite, or granodiorite has a thermal parameterin this range (ref, 2) . It is interesting to notethat the measured bearing strength of such pow-ders is sufficient to be consistent with that ofSurveyor I resting on the lunar surface (ref. 3) .Further, the site is in a relatively dark area,where the albedo or solar reflectance is lowerthan the average. ( J . M. Saari estimates the localalbedo to be 0.052.)

Observations Based on Spacecraft DataA rather firm conclusion can be drawn from

temperatures at many locations throughout thespacecraft during its operation on the lunar sur-face. The spacecraft temperatures are a t levelsto be expected with clean external thermal-radiating surfaces. This strongly indicates thatthe surfaces have essentially no dust on them. Itshould be noted that thermal conditions of thelunar surface have little effect on temperatures atmost spacecraft locations because the undersideof the spacecraft has a highly reflecting metallicsurface.

The temperatures of a few of the external sur-faces on Surveyor I are determined primarily b ylieat exchange with the lunar surface and withdeep space. These spacecraft surfaces are ratherwell insulated, in tcrms of both conduction andradiation, from the remainder of the spacecraft.Th e portion of t he lunar surface which deter -mines the spacecraft temperatures is very local-izcd: 80 percent of the radiation view factor fromthe selected spacecraft surface to the Moon ismade up of approximately 1OOO ft2 (100 mz)adjacent to the spacecraft.

A very preliminary estimate of the lunar sur-face brightness temperature at 1200 GMT, June2, 1966, is 180O F. (ref. 4 ) . This estimate, based


27/46

on iiieasnred spacecraft teiiiperiittircs, is for theappropriiite Sun elevation angle of 31 deg and anassuiiiecl Imiiir s t irfnce therrn a1 emit t aiice of 1O.Th e \ d u e of lS0 F. ma!- be coiii~~aredit11 aprelimiiiarp prediction of a iocal luiiar surfacebrightness temperatu re of 130 F. deril-ed fromEarth-based measurements. Simplified thermalmodels of both the spacecraft ;iiicl tlie iiiiiar sur-face were used in iiiakiiig these estimates. -4intich more detailed aniil!-sis is necessary bkforeit can be confiniiecl tliat the local surface tem-perature of the \loon. at the Surveyor 1 landingsite but \\.ithout effects introduced by the space-craft, is \\,ariiier than the a\.er;igc for tliat portionof the \loon.

Lunar Surface Topography and GeologyIntroduction

television camera on th e Surveyor I spacecraftduring the first five days after land in^^. Duringthis period, the lunar surface \vas olwm-edthrough S u n elex-ation angles ranging from 28to about SS deg. - in immense quaiitit!. of de-tailed information ahoiit the local lunar sur-face is contained in the pictiires: \\-e report heretlit first scientific results obtained from the fore-no( i i and lunar iioon ph( tograplis .

The Surveyor tele\ision c:iiiiera \viis operatedin t\vo modes: one in v-hicli the picturc is com-posed of 200 tele\ision scan lines, and a secondhigher-resolutioii mode in \\-liich the picturc iscomposed of 600 sc;m lines. .I total of 14 pic-tures in the 300-line mode ;ind 33986 in the 600-line mode \\-ere obtained. The 600-line Sur\-eyortelevision pictures are o f superior qualit!. iintlma!- be cornpiired fa\mxl,l!. \\.it11 the liinar tcle-\.ision pictures acqiiircd I>!- thy Ranger space.-craft. The Sur\.e!.or pictrircs :ire cxcc~ptioiiidl!.frec of colicrent noise i ind she\\- \CY!- littlc shad-ing of the field, o\\.iiig to the rclati\-cl!- uniformresponse of th e vidicon targe t.

The calibrated :ingular resolutioi1 of th(b Sti r -\.e!.or camera 01 mr at 1.5 percc~iit rolati\.e R -spoiise) is ahoiit half the aiigiilnr rc~sol~~tionftlic average liiiiiian eye. The g r o u i d resoliitioiinear one of tlie spacecraft footpxl s. nlmut 1 .6in from the camera, AS measured froni pictures

FOCH IIIOL-S.CiD PlCTCRES \r-er


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22 SURVEYOR I : A PRELIMINARY REPORT1 2

, .0

t2 0.8z

LL

0

0.6ca$ 0.48

0.2

0

0 F18 W E N SHUTTER

0 01 0 1 01 10E X P O S U R E , I I ~ c d ~ i e c

FK:WIU.:7.- Ca1il)r:ition data fo r thv Surveyor I tcle-vision cmicra illustrating dynamic range.

can be extended to about 95 000 to 1. Finally,the sensitivity of the camera to very faint ob-jects can be increased still further, by a factorof aliout 40 over the open shutter mode, bymeans of sevc~al ininiites exposure (integra-tion mode).

Tlic color filtcrs i n thc camera filter wheel\wi-e sc~lccr d so that tl C ovcra11 caincw- il t erstandard color matching functions of colorimetryspcctral r~spoI1se (fig. 18) \ \ O l I l d mutcl1 the

100 0 -n o 0 -L

YYI& 600-wLw-5 400-J

200 -

1

1

;S w c ~ l l IS is possi1)lc \v i l l i siiiglc, filtcrs (fig. I$)).111o r t l c ~ o maintiiin c*olorinrcbtric di1)ratioii a i i drnliuncc tlic t1ctc)ction of color differciiccs, tlic,photometric target is equipped with thrw colorso f purity and dominant wavelength that boundthe gamut of normal rock colors. Figure 20

shows the appearance of the target as seen onthe lunar surface through the three color filters.The lens assembly of the Surveyor televisioncamera is constructed to provide a variable focallength, ranging from 25 to 100 mm. Th e camerais normally operated at either the long or shortfocal-length extremum, the 25-mm focal lengthresulting in a 25.4-deg optical field of view,and the 100-mm focal length resulting in a6.4-dcg field of view. For convenience, we referto tlie former ius a wide-angle frame and tothe latter a s a narrow-angle frame.The camera has been operated to provide awide variety of information (table 1). Severalwide-angle frame panoramas have been taken oftlie lunar scene on different days and withdifferent color filters. (A complete wide-angleframe panorama requires about 120 frames. )Several sectors of tlie complete panorama havealso been taken in narrow-angle frames on dif-ferent days and with color filters. (A completen,irro\~~-,ungle rame panoranxi requires nearly1000 frames.) Surveys of two of the spacecraftfootpads and of imprints on the lunar surfaceleft b y tlie crushable blocks hcneath the frameof the spacecraft have been conducted on each

z

l ~ i ( ; t i i w 18.- :rap11 of the overall camcra-filter spectralrcspotisc illustrating thv fit to thc standardCIE ( Comniission Ititcmationnlc lI


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~~

SURVEYO R I : A P R E I . I M l S . U 3 Y R E P O R T 23TABLE .- Categories of telecision pictnrcs take n

cltrring I t r i m forenoon and noon

200-line pictures600-line pictures

\\'icle-angle frame panoramasNarrow-angle frame panoramas\Vide-angle f rame panoramasNarrow-angle frame panoramasFootpad surveyCrushable block imprint wrveyG as jet experimentStar surveyPhotometric and color

calibration targetStudy of objects of special inter-

est and verification frames foraperture, focus and position

TOTAL

\vith color filters\vith color filters

Approxinrat rnunrherof frames_ _ _ _1439 0

11608701160

10030302 0

100

126

successive day. On two days, the attitude-con-trol jets mounted on the legs of the spacecraftwere fired, in an experiment to determine\vhether the gas emitted would disturb the sur-

face: the effects were searched for by compari-son of television pictures taken during and afterthe firing of the jets with pictures taken before.Repeated photographs were taken of t he photo-metric and color calibration target each dayto provide control for the photometric reduc-tion of the pictures. Finally, several objects ofspecial interest, such as large rocks close tothe spacecraft, were esamined with additionalphotographic coverage, in order to pro\.1d e maz-imum information on the shape, testure, andcolor of these objects.

In order to measure the photometric func-tion of the local lunar surface and various ob-jects on the surface, and to map the surfacetopographically by use of shadows and byphotometric techniques, it is necessary to sur-vey the surface repeatedly at different positionsof the Sun. Different kinds of information areprovided about the surface, furthermore, atdifferent angles of solar illumination. The finetexture and very ~ h a l l o ~elief features ai-eliest shown at glancing solar illumination,whereas differences in albedo and color are bestdetermined when the Sun is high, or when thephase angle of a given image element is very

FIGL-RE0. - Photometric target on footpad 2 of thc Stlr\cyor spacecr,ift. Th r t;lrcc,t is nwtlfor photomtltrie calil~ationof the tc.lr\-ision camera during lunar opvratiot>.Frame ( a ) ic ol~scmw l hrough k' filter, ( h ) is observed through S;' filter, an d( c ) is observed through z' filtrr.


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smal l . Although 4000 pictures have lieen ac -quired :it the time of writing, the p1iotogr;ipIiicdata iire far from complete, and many thousandadditional pictures will be needed to investigatetlioroiighly the fentures of interest in tlie field ofvicw.locat ion of the Spacecraf t f rom landscap e Featureso n the Hor izon

At least six fcatww on tlic Surveyor pan-orama pictures c m hc, identifictl a s elcvatcd tcr-rain lying at ;I greater distance: t h m the ordinarynear Iiorizon of aliout 2 kin. A low mountainridgc to tlic northeast is tlic outstmding es -iimple. The ordinary ncw horizon in front ofthe distant features can gcncral ly be identifictl;is ;i re1:itivcly sharp c1emarc:ition lictween thclforeground and tlie distant elevated terriiin,which is l,riglitc,r and smootlier i n silhouette,.All of the distant fcatiires recognized ;ire con-ccwtratcd in the northern part of the horizon.Figure 21 shows ;i mosaic of the liorizon lxx-twcwi northwcst mcl northeast, with tlie fcii-trircs idcntifietl. Their charncteristics ;ire slim-miirizcd in t a l h 2.

A 65 N 2 7 O I < 11.2 "-54 0.44 1 0 013 98.2 N 6" \\' 2,s 0.79 0.24 75< 102.0 K 10" \' 0.3 0.081) 105.8 iX 13" V 1.5 0 . 52 0.15 52b: 124.0 r\' 32O \f ' 0.5 0.121 88.0 X3 "l 3; 0.5 0.15 0.04 1 0* T h e figures f o r t h e width and height of the features are

f o r th e parts visible over lhe hort7on. T h e y :Ire c:ilcul:ited onth e b:i\i.; of th e Site I loc;ition ( s e e t e x t ) .

The occiirrcnce of t h r clistmit horizon f c a -turrs is consistent with tlw gcwxil location o ftlic Survcyor landing sitc i n tlic: nortliwst por-tion of ;i plain north of Flnmstcctl cncirclctlby hills ant1 low nioiintnins. In this a r c x , thercarc scvcral spwific sitcs i n ii circular rcgion ofapproximately 7-kin rudius from which most of

the o l ~ e r ~ e t leatures can be explained 1 3 ~telescopically observed Iocal lunar topogrqhy.Tubk 3 gives the location of two of tlie sites.

Figlire 22 shows tlie location of these sites ona Liiiinr Chart and illustrates, fo r the case ofSitc I , the degree to which the horizon featuresol~scrved by Surveyor can be explained bykno\vn moiintains. Site I1 coincides with thesitc tlcduced from trajectory tracking data. Itis proscnted in figure 22 with an ellipse sliow-ing thc 2-rr uncertainty in its location based on;i prcliminary reduction of th e tracking dnta.Among the sites stiitlicd, Sitc I appexs some-\vliat prefera1,le from known features of thel i inar landscape. It best explains the mostprominent feature, A, even though the twoininor featurcls, C and E, are not esplaincd ind c t d .

At prcwnt, it is not clear whether the dis-agrccvnent ( a h i t S km outside tlic 2- ,r errorellipse o f tlic: solution obtaincd from tracking)1)cbtwcvx tlw site deduced from trajectory track-ing and the preferred sitc determined fromtopography is to l x taken ;i s a eiiiise for con-w r n . It is to lw expected that later pictures oftlw liorizon features mid comparison withtclcscopie o r Lunar Orbiter photographs of thisrc,gion will providc sufficient data for a muchmort precisc: location of tlic landing site of Sur-v e y o r with rcspect to k n o w n selenographic fea-tr1rc.s.

Slope of the Surveyor I l a n d i n g S it eon the Ki lometer Scale

Tlw position of the horizon on the S~irvcyorpinoriimic pictiires (pirticularly in the narrow-m g l c frmws), together with the calilmitedc;imc>r;ipointing angles, c: in be used to establishth e local avcqyige iliclination of the landing sitc


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130 120 110 100 90 80 70 60

F I GWE 1. - Vitle-;ingle paiiorama of the liinar horizon in the northcrn quxlraiit a s 01)-s e n d by Sun-eyor I . The region covcrcd is from 55 to 130 azimuth (cameracoordinates ) ; Su n elevation is npprosimntcly 50. \lost of the curvnture of th chorizon arises from thr nonvrrtical m onnti nc of the camera.

FIGCXE2, - Survcyor I Inntling sites its deducc.d from horizon fentnrrTwo sites that svem compatble \i.ith these features ; msho\vn. Site I 1 coincides \vitthe site deduced from traietory tracking data. The c.lliparound Site I1 is thc 2-(, erroBase map--ACIC Lun ar ChaLrZC 75.


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26 SURVEYOR I: h PRELIMINARY REPORTterrain relative to the spacecraft axis. This in-clination can be determined to a fraction of adegree, and, if the horizon is relatively distant,applies on a kilometer scale.

Observations of the horizon positions can beconverted to true slopes of the terrain oncethe attitude of the spacecraft relative to thelocal astronomical vertical is known. This is de-termined, in turn, by using the television camerato take star pictures. For this purpose, thecamera was used in an open shutter mode. Therelatively high luminance of the lunar terrain,however, resulted in a high background in day-time measurements. So far, the images of twostars, Sirius and Canopus, have been obtained.Ro~igh nalog reduction of the stellar positiondata shows that the spacecraft asis is tilted fromthe astronomical vertical by 1.7 10 . 5 deg in adirection a little south of east. Repeated obser-vations of points on the horizon show that thespacecraft cannot have shifted attitude morethan a fen7 tenths of a degree since the first dayafter landing. Oliservation of the landing pi dssuggests that they penetrated the surface nearlyequdly. This implies that the spacecraft tiltis close to the slope of the lunar surface im-mediately 1,eneatli the spacecraft.

A dctailed examination of the horizon posi-tions, correctcd for this spacecraft tilt, has beenmade for 6.5 directions over a range of azimuthof 850 deg extending from the north to thesouthwest. The results show that the Moon, atthe Surveyor I landing site, is both relativelysmooth and nearly level on a kilometer scale.The standard deviation of the angle to theliorizon is only 0.7 deg. The average horizonposition i n the three qiiadrants examined is thesamc within 0.5 dcg. More refined treatmentof the o1)scrvations can 1)c expected to rcduccthe standard dcvi,It 011.

Gen era l Morphology a nd St ructure of Terra inAround the Spacecraf t

Surveyor I is resting on a part of Oceanuslroccllarum partially encloscd within a circleof hills and small mountains on the rim crestof an ancient crater that is almost completelyburied beneath the mare material of theOceanus. This ancient crater is about 100 km

in diameter. The landing site is along the eastborder of a dark patch on the mare surface,which is the smoothest part of the mare withinthe mountain circle. The nearest small craterthat can be easily resolved at the telescope isabout 1 km in diameter and lies about 10 kmto the east of our best estimate of the landingsite.

The terrain within 1 to 2 km surrounding thelanding site, as observed from the Surveyor pic-tures, is a gently rolling surface studded withcraters ranging in diameter from a few centi-meters to several hundred meters. Severalcraters that probably range in size from a littleless than 100 m to perhaps as much as % kmhave been recognized along the horizon. Theirtrue diameters cannot be accurately estimated.They range in angular width from about 15 to36 deg . One of these craters, which lies slightlysouth of east of the spacecraft, has a prominentraised rim about 5 to 10 m high (fig. 83). Thec>uteriorslopes of this crater rim exhibit a maxi-mum inclination to the horizon of about 11.5deg. The visible rim crest and exterior slopes ofthc rim are strewn with coarse ldocky debris.Two larger hut more distant craters southeastof the spacecraft have relatively low, in-conspicuous rims, although patches of coarseblocks can be seen very close to the horizon onthe rim of one of these cr t ers.

Ahout 20 craters, that range in diameter fromnhout 3 to 100 m, have been recognized in thefield of view below the horizon. These cratershavc been observed only under relatively highsolar illumination, and more craters of com-parable size will probably be recognized at lowSun angles. One of the most prominent of theselarger craters (fig. 2 4 , which lies about 11 mfrom the spacecraft, is about 3 m wide andabout 2 / 3 m in depth. It has a distinct but ir-regular raised rim and a lumpy appearing innerwall that slopes somewhat less than 28 deg.Most of the other craters in the size range of3 to 20 m have low, rounded, inconspicuousrims or are rimless. The larger craters, takentogether, resemble in distribution and form thecraters of equivalent size observed in the Rangerphotographs in h/Iare Cognitum and MareTranquillitatis.


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FIKRE 2 3 . - Sector of rim of large crater on horizon, southeast of the spncctraft. Coarserblocks are probably more than a meter in \vidth.

The smaller craters, ranging in diameter froma few centimeters to 3 m, are generally sh~d lo \vand difficult to observe under high solar illum-ination. Most of them either have low roundedrims or are apparently rimless. \\;here they canbe observed, close to the spacecraft, they arerelatively closely spaced and may cover as much2s 50 percent of the surface. ll or e details on

their size, shape, and spatial distribution a reexpected to be obtained from pictures that willbe taken in the late lunar afternoon.

Distribution of Blocks and Coarser DebrisThe lunar surface in the vicinity of the space-

craft is littered \\it11 coarse blocks and frag-ments. hlost of the more prominent hlocks in


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.98 SURI'EYOR I: A PRELIlIISARY REPORT

the field of view appear to havc ;I ncnrly ran-cloiii distrilmtion over the siirfacc,, hut significantconcentrations of ldocks and f i n c ~ ulildc occurin ccrtain Iowtions. A strc\\m fictltl o f \.er!.co;irsr, rclativc.ly closc~l!. sp; ~cc d blocks siir-rounds tlw cratcr notcd on the cwtern horizon(fig. 2 3 ) . This field cstcwtls f r o m tlic rim crestof the cra ter out to ;I t1ist;uicc. of nlmut 1 cr;\tcrdiamctcr in c d i clirc,ction along t l i r horizon.1 t is liigld!- prol)al)l(> hat tlw large majority of


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SUR\EYOR I: .\ PRELI\IIS.1RT REP O RT 29

across. Other blocks, associated with a still moredistant crater rim. are also probably more than1 111 across; some of them have anziilar wiclthsof more than 20 min of arc.

In the foreground and middle distance a rescattered patches of rubble with an almage grainsize much less than that of the nearby coarserblocks but significantly greater than the averageresol\-able grain size of nearby parts of the sur-face. These patches resemble flattened piles ofrubble ckriwd from tlie slow-speed impact ofweakl!? coli rrent mater ial tliron-n out of experi-mental craters produced b y explosion and impcton Earth. Some of the patches around Survt.yor Ioccur \vithin the shallow depressions. \vliicli IIM!be secondary-impact craters.hlost of the coarser blocks scattered aboiit thcsurface appear to be equant in s l i i ~ p ~d RICi:iigi!ilr to s u b z ~ g u l a r ; small niiiiilxr ;UT S U ~ -

rottntled. The majority of tlie angiilar blocksappear to rest 011 the surface. \\-it11 perhaps SOto 90 pcrcent of their hiilk abow the surfacelc\.el. h l a n y of the round blocks seem to be par-tially hnried; in some cases. perhaps 50 percentor more of the block is b e h v tlie surface le\-el.So ne of tlie fragments or blocks is seen to resto n peclrstals. as lias betxn suggested b!- someSoviet scientists on the basis of the Luna I S

Th e angular blocks. especially those on the rimof the prominent crater o n the eastern liorizon,a r c typicall!- faceted a s tliougli broken alongjoints :ind prc~-ezisting fracturcs. Some, of thelarge blocks do ng the Iiori7on appear to be rest-ing on top of tlie siirface md 1ial.c demonstrableo\-erliangs (fig. 2 3 ) . Tliesc blocks m u s t havesti1xt;mtial cohesion a n d shear strcngtli. par-ticularly if they ha\^ arri\d in their present

p1iotogr;lphs.


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30 SURVEYOR I: A PR ELIMIN A R Y R EPO R T

I

FICIJIW6. - Block with r oundc d etlgcs :nit1 associatcyl fragments, sonth\vc.st of spacccraft.Note mottling and fractures o n main I)lock.

position by ejection from the crater. Th e very rrlat ivc~ly trong single llieces of rock.large majority of the coarser blocks have, in aclcli-tion, ii dcmonstrably higher albcdo than most oft he r a t of the lunar surface i n the ficlcl of vicw.This is particolnrly noticcnblr under high Sun,when the blocks stand oiit prominently as brightspots. These data suggest that the blocks arccomposecl of material somewhat different physi-cally from the general finer-grained matrix of thelunar surface and that most of thcm consist of


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SVRVEYOR I: A PRELIlrlI!i;ARY REPORT 31distinctly marked with close-spaced dark spotsa few millimeters across. Most of the spots areclearly shadows within pores or cavities in therock surface. They are so close in size to theresolution limit of the pictures that the characterof the cavities cannot be determined with con-fidence. They may be intergranular pore spacesin a relatively coarse-grained rock, or they maybe vesicles. The spots exhibit a distinct elonga-tion and pattern, however, ~ h i c hesembles thatproduced b y flowage and distortion of vesiclesin a volcanic rock. It seems quite possible thatthe block observed is a rock congealed from agaseous melt. Such a melt could have been pro-duced either by strong shock or by vulcanism,and the rock could be an impactite, a volcanicbomb, or a fragment from the top of a vesicularlava flow.

The second block close to the spacecraft isquite different from the first. It is angular inshape, with well developed facets that are slightlyrounded at the corners and at the edges. Theblock appears to be devoid of resolvable gran-ularity, but it is distinctively mottled. The lighterparts of the block tend to stand out as smallknobs. The block has the appearance of beingsomewhat eroded, and the brighter knobs maystand out as a result of differential erosion. Oneof the most striking things about this block is avery pronounced set of fractures, which appearto intersect and which resemble the cleavageplanes produced during plastic flow of rock undermoderately high shock pressure. Another strikingfeature is that the block lies in a swarm of some-what similar, smaller fragments, which are strewnout in the direction of elongation of the mainblock. At least SO separate pieces are present inthe swarm. Many of these fragments and part ofthe base of the block appear to be partiallyburied in the lunar surface, but a fen7 fragmentsseem to rest on the surface. The impressiongained is that the main piece has broken up,perhaps on impact with the surface, and that itmay have relatively lotv shear strength. S o ini-pact or skid marks are observable around theblock area or pieces, however. The swanll offragments may have been lying on the surfacefor a considerable period of time and been pnr-tlaiiy buried b y yuuiigei, $ X X ~ebris.

Size Distr ibution of Debr is on t he lunar Sur f aceand the Character ist ics of t he F ine Ma t r i xThe spacecraft appears to be located in a rela-

tively representative part of the terrain in thefield of view, and a first attempt has been madeto evaluate the size-frequency distribution offragments making up the observable lunar sur-face from a series of narrow-angle pictures ofsmall areas relatively near the spacecraft. Thepictures used were taken under comparativelyhigh Sun; therefore, only the more prominentgrains are recognizable. It is expected that ourfirst estimates of the size-frequency distributionnd l be slightly biased toward underestimatingthe actual average grain size.

Four sample areas (fig. 27), 0.23, .90,3.5, and50 m in size, were selected on the undisturbedsurface, ranging in mean distance from 2.5 toabout 20 m from the camera. The areas andgrain sizes were estimated bj7 transformation ofthe pictures to a nominal flat surface defined asbeing at a base of the spacecraft footpads. Allsharply formed fragments and grains that areeasily recognizable in the pictures were meas-ured and counted; these amounted to a total of825, ranging in diameter from 1 mm to morethan 1 m.

The integral frequency distribution of thegrains, normalized to an area of 100 m?, for eachof the sample areas is shown in figure 97. Jt canhe seen from the figme that the sample areasselected provide overlapping coverage in resolu-tion and that the distribution functions of thegrains in each area may be roughl\r describedas segments of one overall distribution function.There is clearly some IieterogeneiQ- from onesmall area to another, as would be expected fromexamination of the lunar surface within the fieldof vie\\., but the general size-frequency distribu-tion of fragments on the local lunar surface isprobably fairly well estimated by the lower solidline i n the figure. This line is the plot of the fol-louing equ1ton:N = 3 x 10; ? , - 1 i Twhere

A: = cumulative nuniber of grains!/ = diameter of grains in mm

This function is bounded at an upper size limit


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32 SURVEYOR I: A PRELI3lINARY REPORT

!4 I 2 4 8mrn 1.6 3.2 6.4 12.8 25.6 51.2 I 2crn rn

of about 1 to 2 m but probably extends to p r -tick sizes considerably finer than 1 mm (tliclimit of the observational da ta) . About one Mock1 in across may be expected to be found on c d i100 in' of the surface. Tlie mean grain siye ofthe surface material, averaged by pirticle mass,is probably of the order of about 1 nini. Theform and const;ints of this s i x distribution frinc-tion arc closely similar to tlic si7c-frequency dis-tribution of friigmcnts lirodricctl hy criishing andgrinding of rocks in I )a l l mills and by rcytitivc>ini pct of rock surfaces.

Tlic matrix of the unresolved material hetweclnthe grains, w h r c observed very closc to tlicspiicecraft, shows a pectiliar patcliiness of albedowhen observed tinder high Sun. These patchesmay be caused by successive thin deposits of

very fine-grained material derived from differentareas.Material Ejected by Impact of the

Spacecraft FootpadsAroiind footpads 2 and 3 of tlie spacecraft areray-like deposits of ejected material extendingout in certain directions as far as several tens ofcentimeters from the edge of each footpad (seefig. 1 4 ) . These deposits form a distinct raisedridge near each of the footpads. The ejected ma-terial differs both in albedo and in texture fromthe material exposed on the adjacent undisturbedparts of tlie lunar surface. The average albedoof the ejected material is nearly 30 percent lowerthan that at tlie undisturbed surface, as estimatedby the methods described in the following sec-

tion. Tlie material is composed of distinctlycoarser lumps or fragments of ejecta than theadjacent undisturbed surface material.Tlie integral size-frequency distribution of theIrimps of tlic spacecraft footpad ejecta was esti-mated from two sample areas of about 100 and50 cm', respectively, on either side of footpad 2.A total of about 950 grains and lumps werecounted. Th e observed size-frequency distribu-tions are shown in figure 27, and it can be seenthat tlie footpad ejecta are about an order ofmagnitude coarser than the material of the sur-rounding lunar surface. These data strongly sug-gest tliat the observed lumps in the freshlyejected material are probably aggregates of muchfiner grains. The size distribution of the finergrains composing the aggregates is probablygiven by the memi size distriliution function forthe general surround ing surface. In all likelihood,the lumps are only weakly consolidated andcoiilcl lie disaggregated into their constituentgrains under a modest presslire or agitation.Similar lumps that may be formcd around nat-lira1 impact craters a r e l~roli.il)ly quickly brokcndown by the ballistic rain of small particles onthe Irinar siirfaccb.

Photometry and ColorimetryOn e of the important functions of the tele-vision camera is its use a s a photometer. For the

first time, the observable photometric function


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.. 33URVETOR I : -1 RELIXKISAUW REPORT

FIGPRE7. C o n t in u e d . A r e a 1

of part of the lunar surface can now be coni-pared nith the megascopic texture of tlic sur-face. Furthermore, a much more complete meas-ure of th e function can be obtained nt one lunarlocation than from Earth-based obser\.ation, andit will be possible to test i n detail tlie assumedsymmetry or degeneracy of the photometricf::nctizn.

The location of the landing site near the lunareqiiator en,tbled measiirements o f tlie surfaceluminance to be made almost e\my d a y i n th eplane of tlie Snn-slope normal. The measure-ments were calibrated b y photographing tliephotometric target beforc and after each survey.Th e stabilitj. of the camera between these nieas-urements \vas about 10 percent. Three frames of


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s34 SURVEYOR I: A PR ELIMIN A R Y R EPO R T

F~c:viuc27, Continucatl. Arcn 2.

the pliotomctric target w c w , selcctcd fo r r c ya t -ability chccks T1 I( variation lw wccn t i r w se-qtiential f rnmcs was appro\-imntcly 2 1mwnt .

Tlie pliotomctric target W;IS calibrated beforcflight by ;I goniopliotometer, and its orientationon the spacecraft made normal to tlie camerascenter line of sight. The calibration data havebeen used in conjunction with the photometric

angles of phase , incidence, and emergence topredict luminance values for c ~ ~ l iarget step.

llic video signal has been recorded on mag-netic tape and by a flying spot scanner photorecorder. Control of the processing of the filmhas indicated that a high degree of stability existsbetween the film records. A transfer character-istic from s ~ c h negative to tlie photometric


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35URVEYOR 1: A lRELI3lINARY REPORT

FIGURE7 , Continued. Area 3 .

target is shown in figure 28. The latitude of thefilm (SO-337) is ,great enough so that the entirevideo transfer characteristic may be recordedon the linear portion of the film.

As a preliminary check on the use of the cam-era as a photometer, the scene luminance wasmeasured for parts of the lunar surface stir-rounding the pad upon which tile p l i ~ t ~ ~ ~ t r i c

target w as mounted. By fitting the measuredscene luminance to the photometric functionderived from the telescopic measurements ofFedorets (ref. 5 ) , an estimate of 7.7 percent forthe normal albedo \viis derived for the parts ofthe surface which appeared to be undisturbedb y the pad (fig. 14). The estimated albedo fo rt ! ~istiirhed areas was about 2 percent lower.


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36 SURVEYOR I: A PRELIMINARY REPORT 8


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SURVEYOR I : PRELI.\IIS.ARY REPORT 37so obtained permit estimates to be made of thespectral reflectances. Again, to check and main-tain the calibration of the camera-filter combina-each filter before and after the smvey (fig. 20) .Preliminary examination of the prominent mottledrock lying just southwest of the spacecraft (fig.26) indicates that any color differences that maybe present in the surface of the rock are verysmall. Much more careful processing of the videodata is necessary before subtle color differences

w f l l l F FILTER tion, the photometric target was observed with7,

j~

,

-ii04

0 2 can he measured.

4000 Lunar Surface Electrical Propertiesoc 200 .w scc BW lorn 2000LUMINANCE 0 , LrnlftFICVRE8. - Total television system transfer character-

istic function determined from observationof th e photometric target on the spacecraftleg during lunar operation.

FIVE .XYS AFTER THE TOVCHDOWS of Surveyor1, the radar signal-strengt11 data \\ere still underdetailed analysis to determine the average radarcross section in the vicinity of the landing site.The radar frequencies used by the spacecraftwere 9 300, 12 900, and 13 300 Mc. If it provespossible to deduce the effective reflectivity, effortwill be made to calculate some of the electricalcharacteristics of the lunar surface. N o tentativeconclusions, however, are as yet \Tarranted atthe time of this w-riting.

Several color surveys using the three filterswere made, beginning the third day after touch-down. The main purpose of thesc surveys was toascertain whether or not there are color differ-ences in the vicinity of the spacecraft. The data

REFERENCES1 . SHORTHILL,R. W.,SD SAARI, . If.,1sofherm.s i n the Evuutor ia l Rcgion of thc Total lyEclipsed Moon: Boeing Geo-Astrophysics Lalmratory, Report DI-82-0530, Seattle, \\-ash-

ington, April 1966.2. ~ V E C H S L E R ,. E., ASD G L A ~ E H , . E., Thermal Properties of Postulated Lunar Surface

Materials, T h e Ltrnur Sur face Lmyer, Sdi~lx iryz. 11.,and Glaser, P. E.. Editors, Se\\-York and London, Academic Press, 1964. pp. 389-410.

3. JAFFE, L. D., \Iechanical and Thermal hleasurements on Simulated Lunar Surfaccllaterials, T h e Lunar Sur face Lnycr , Salisbury, J . \\-., and Glascr, P. E. , Editors, 5 e \ vTork and London, A4cademic Press, 1964, pp. 355-380.

4. H . KSVDSEX of Huglie5 Aircraft Coinpan!- suggested \vorking f rom the outer cani.;tc.rtemperature on Compartments A and B to establish lunar surface temperatures. h i . G R ~ A Iof JPL carried out th e premlimin;tr>- thermal analysis.

5. FEDORETS,. A ,, Photographic Photometry of the Lunar Surface, Rcports of th e A.stro-tiotnical Obscrcator!/ of thc Chcirkotc St n t c t n i r c w i t y , 101. 2. 1952.


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c

APPENDIX A

Membership of Surveyor Scientific Evaluation and Analysis TeamT o n ic ct prograni scientific olijccticcs, tlic Surveyor Scicnfific Evaluation

( rnd Aiinlysis Tcwm tctis estciblishcrl t o j)roc;irlc II nicuiis to s t t i d y the scientifictlatci prorliicctl. 111dtl i t iorz to t l ie nitrin Awlysis Tcrin i , foiir assocititctl workinggrotips (Ltincir Srirfacc Alcchaniccrl Properties, Tlicr~ncil Propcrties, T o p l o g ! /t i t i d Geology, t int1 Elcctriccl? Propcrtics) tcew fortiictl t o inocstigntc in rlctailunriotis aspects of tlic data. Analysis Team nicnibcrs incltitlc tlie Zncestigators01 1 latcr Srirccyor niissiolis, tlic Jc t Proptilsion Lob ora tory Stirocyor Projc>ct Sci-cntist, nntl the Nationcil Aeronautics and Sp(icc Atlniinistration Stirveyor ProgrtitllScietitist. Alcinlicrs of tlicse grori1)s tclio contribtitctl t o the respective scctiorisof this cirticlc tirc:

Surveyor Scientif ic Evaluation and Analysis Tea m

Membership of Working Groupslunar Surface Mechanica l Propert ies

Lunar Surface Thermal PropertiesJ. 1. C O N L I ,l i . 13. 1I%11. II . CANPAYW. A. I ~ A C E ~ I E Y E I ~J . W . LUC:AS,htiirmcitiJ . hl. S A A H I

J r t Iropulsion Ijalx)r:itoryhi;inncd Slxicccrnft CrntcrI lugl~csAircraft CompanyJet lropulsion LaboratoryJe t lropnlsion LalmratoryBoeirig Scicmce Lab o ra to ry

38


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SLTRVEPOR I: A PRELIMIS.lR1 REPORT 39

lunar Sur face Topography and Geo logyE. M. SHOEMAKER U S . Geological SurveyW. i. ALEXANDER Temple Uni ken ityJ. L. DRAW lfanned Spacecraft CcnterE. C . XIORRIS U.S. Ckological SurveyJ. J. RESKIL~OS, cting Chuirniczn Jet Propulsion Laboratory,4. TLRKE~ICH Univcnity of Chicago

Lunar Surface Electrical PropertiesIf7.E. B ~ o n . s , R., ChairmnnR. A. DIUOSD. 0. ~IUHLEIIA?: Cornel1 Univer sity

Jet Propulsion LaboratoryIlughes *4ircraft Company

APPENDIX BSurveyor Management Team

Nit ional11. E. SEW ELLE. 11. CORTHIGI~T

0.\I. S I C K SB. X\IIL\VITLKIIV . J.\KOiiOn.SKIF. .\. Z I m x a sS. E. DWORSIK

If . H. PICKERISGA. R. LI-EUECKER . J. PAIIKI;SI I . I f . HKLCSDIt.E. GIBERSOXT. F. C-\LT5CliIL. D. J 4 F F ES . A. RESZETTI

7.13. RICHUU%O~F. . ~DLERR. L. RODERICKR. E. SEARSR. R. GUSTEHF. G. ~ I I L L E R

Aeronautics and Space Administrat ionAssociate .kIniini.;trator for Space Scitnce and Application.;Deputy Associ;tte ridmini\trator for Space Scimce an dDeputy Associate Administrator for Space Scicmcc andDirector, IAiinnr nd Planetary Program.;Suncyor Program 1tan:igerSnrvcyor Program EngineerSurveyor Program EngineerSurveyor Progriun Scientist

ApplicationsApp1ic:itions ( l


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T he aeronautical and space activities of the U nit ed Stdtes shall beconducted so as to contribute . . . t o the expansion of human knowl-edge of phenomena in the atmoJphere and space. Th e Administrationshall provide for the widest practicable and appropriate disseminationof inform ation concerning its activities and th e results thereof.

-NATIONALERONAUTICSN D S P A C E ACT OF 1958

NASA SCIENTIFIC A N D TECHNICAL PUBLICATIONSTECHNICAL REPORTS: Scientific and technical information consideredimportant, complete, and a lasting contribution to existing knowledge.TECHNICAL NOTES:importance as a contribution to existing knowledge.TECHNICAL MEMORANDUMS:tion because of preliminary data, security classification, or other reasons.CONTRACTOR REPORTS:with a NASA contract or grant and released under NASA auspices.TECHNICAL TRANSLATIONS: Information published in a foreignlanguage considered to merit NASA distribution in English.SPECIAL PUBLICATIONS: Information derived from or of value to NASAactivities. Publications include conference proceedings, monographs, datacompilations, handbooks, sourcebooks, and special bibliographies.TECHNOLOGY UTILIZATION PUBLICATIONS: Information on tech-nology used by NASA that may be of particular interest in commercial and othernonaerospace applications. Publications include Tech Briefs; TechnologyUtilization Reports and Notes; and Technology Surveys.

Information less broad in scope but nevertheless of

Information receiving limited distribu-

Technical information generated in connection

Detai ls on the av ai labi l i ty o f these publications may be obta ined from:

SCIENTIFIC AND TECHNICAL INFORMATION DIVISIONNATIONAL AERONAUTICS AND SPACE ADMINISTRATION

Washington, D.C. PO546

surveyor 1 a preliminary report

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