Surveyor C Press Kit

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NAIIhNAL ALRO NAMII(S AND SPACE ADMINISTRATION TELS W() -WASH INGTON DC 2046 W( ) i-'.97FOR RELEASE: FRIDAY A.M.April 14, 1967

RELEASE NO: 67-85

PROJECT: SURVEYOR C(To be launched no earlierthan April 17, 1967)

CONTENTSGENERAL RELEASE -----------------------------------------1-4SURVEYOR BACKGROUND-------------------------------------5-6SURVEYOR C SPACECRAFT----------------------------------7

Frame, Mechanism and Thermal Control----------------7-9Power Subsystem-------------------------------------9-11Telecommunications -------------------------------- 11-12s Propulsion------------------------------------------12-13'Flight Control Subsystem----------------------------13-14Television------------------------------------------15Surface Sampler Experiment-------------------------16-17Engineering Instrumentation------------------------17ATLAS-CENTAUR LAUNCH VEHICLE---------------------------18LAUNCH VEHICLE CHARACTERISTICS-------------------------19-20ATLAS-CENTAUR FLIGHT SEQUENCE--------------------------21TRACKING AND COMMUNICATION----------------------------22-23TRAJECTORY------------------------------------------ -24-25KTLAS-CENTAUR 12/SURVEYOR C FLIGHT PLAN----------------26Launch Periods-------------------------------------26Atlas Phase-----------------------------------------26Centaur Phase---------------------------------------26-27Separation------------------------------------------27First Surveyor Events------------------------------27-28Canopus Acquisition---------------------------------29iMdcourse Maneuver----------------------------------29-30Terminal Sequence-----------------------------------30-31Post-landing Events---------------------------------32ATLAS-CENTAUR AND SURVEYOR TEAMS-----------------------33-39

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NATIONAL AERONAUTICS AND SPACE ADMINISTRATION TELS WA) 1-692'N E W WASHINGTON D C 20546WCFOR RELEASE: FRIDAY A.M.

RELEASE NO: 67-85THIRD SURVEYORLAUNCH SLATED

AT CAPE KENNEDY

Surveyor C, the third United States spacecraft designedto soft land on the Moon, is being prepared for launch fromCape Kennedy, Fla., during the period of April 17 - 21,

The seven-spacecraft Surveyor series is intended todevelop the technology of soft-landing on the Moon and toprovide scientific and engineering data to support the Apollomanned landing program.

Basic information on its lunar landing site that Surveyorwill return to Earth will be photographs taken by a singlesurvey television camera and data provided by other onboardinstrumentation.

Surveyor C is identical to earlier spacecraft in theseries with these exceptions:

-- It will be equipped with a surface sampler instrumentthat can dig into the lunar surface to provide data on lunarsoil characteristics

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-- The spacecraft will be equipped with two flat mirrorsto extend the visual range of the television camera under thespacecraft

-- The Atlas-Centaur launch vehicle will launch Surveyorwith a parking orbit instead of a direct ascent trajectory.The launch, by Atlas-Centaur 12, will be from Complex 36 atCape Kennedy.

The parking orbit launch allows the second stage and thespacecraft to coast in Earth orbit before burning the Centaurstage engines a second time to achieve the required velocityfor lunar flight. This technique gives greater flexibilityin choosing the arrival time at the Noon and allows bettercontrol of lighting conditions on the Moon at the time oflanding.

The Surveyor C mission will last about 65 hours from

lift-off to lunar landing. A large solid propellant retro-rocket and three small vernier rocket engines will slow Surveyorfrom a lunar approach speed of about 6,000 miles-per-hour toabout 10 miles-per-hour for a soft landing.

On the first day of the launch period, April 17, thelaunch can occur between 1:24 a.m., EST and 4:09 a.m.

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-3-Surveyor C will be aimed for a 37-mile-diameter circle

in eastern Oceanus Procellarum (Ocean of Storms) at 230 101West longitude and 30 20' South latitude. The center of thetarget circle is 72 miles southeast of the rim of the craterLansberg and some 56 miles northeast of the Riphaeus moun-tains. The largest crater near the target circle is FraMauro B (five miles in diameter) which is ten miles southeastof the circle.

Within the target area, there are several small visiblecraters. One, about a mile in diameter, lies very close tothe center of the circle. The highest local surface featureis a mountain peak 1,575 feet high lying on the northwestedge of the circle -- about 181 miles from its center. Thetarget site has been photographed by Lunar Orbiters I andIII and is a candidate Apollo landing site.

At launch, Surveyor C will weigh 2,283 pounds. Theretromotor, which will be Jettisoned after burnout, weighs1,444 pounds. After expenditure of liquid propellants andattitude control gas, the landed weight of Surveyor on theMoon will be about 620 pounds.

Except for the surface sampler and mirrors, Surveyor Cwill be equipped identically to its earlier dister spacecraft,carrying a TV camera and engineering instrumentation. It willalso obtain data on the radar reflectivity, mechanical pro-perties, and thermal conditions of the lunar surface.

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Surveyor I soft-landed on the Moon June 2, 1966, andreturned 11,150 high quality photographs of the lunar terrain.It survived eight months on the lunar surface during whichtime it withstood eight cycles of extreme heat and cold.Surveyor II was launched on Sept. 20, 1966, but the mission

failed when one of the three vernier engines failed to igniteduring an attempted midcourse maneuver.

The Surveyor program is directed by NASA's Office ofSpace Science and Applications. Project management is assignedto NASA's Jet Propulsion Laboratory operated by the CaliforniaInstitute of Technology, Pasadena. Hughes Aircraft Co.,under contract to JPL, designed and built the Surveyor space-craft. NASA's Lewis Research Center, Cleveland, is responsiblefor the Atlas first stage booster and fo r the second stageCentaur, both developed by General Dynamics/Convair, San Diego,Calif. Launch operations are directed by Kennedy SpaceCenter, Fla.

Tracking and communication with the Surveyor is theresponsibility of the NASA/JPL Deep Space Network (DSN).The stations assigned to the Surveyor program are Pioneer,at Goldstone in California's Mojave Desert; Robledo, Spain;Ascension Island in the South Atlantic; and Tidbinbilla nearCanberra, Australia. Data from the stations will be trans-mitted to JPL's Space Flight Operations Facility in Pasadena,the command center for the mission.

(END OF GENERAL RELEASE; BACKGROUND INFORMATION FOLLOWS)


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-5-SURVEYOR BACKGROUND

Surveyor I performed the first fully-controlled softlanding on the Moon on June 1, 1966, after a 63-hour, 36-minute flight from Cape Kennedy.Surveyor I landed at a velocity of about 7.5 miles perhour at 2.45 degrees south of the lunar equator and 43.21 de-grees West Longitude in the southwest portion of OceanusProcellarum (Ocean of Storms).During the six weeks following the perfect, three-point landing, the spacecraft's survey television camera tock11,150 high-resolution pictures of the lunar surface for trans-mission to Earth receiving stations, Resolution in some of thecloseups was one-half millimeter or about one-fiftieth of aninch. These pictures showed details of the lunar surface amillion times finer than the best Earth telescope photos.From the pictures were derived the representative colorsof the Moon's surface, an,.accurate view of the terrain up toone and one-half miles surrounding the Surveyor, the effect oflanding a spacecraft upon the lunar surface and pictorialevidence of lunar environmental damage to the spacecraft itself.A section of the mirrored glass radiator atop one of the elec-tronic equipment compartments was shown to be cracked in aphotograph taken during the second Lunar day.The spacecraft also took a number of pictures of thesolar corona (the Sun's upper atmosphere), the planet Jupiterand the first magnitude stars Sirius and Canopus.The television pictures showed that the spacecraft cameto rest on a smooth, nearly level site on the floor of a ghostcrater. The landing site was surrounded by a gently rollingsurface studded with craters and littered with fragmental de-bris. The crestliaes of low mountains were visible beyond thehorizon.By July 13, Surveyor I's 42nd day on the Moon, the space-craft had survived the intense heat of the lunar day (250 de-grees F), the cold of the two-week-long lunar night (minus 260degrees F) and a second full lunar day. Total picture countwas: first lunar day -- June 1 to June 14 -- 10,338; secondday -- July 7 to July 13 -- 812. The total operating time ofSurveyor I (time during which signals were received from thespacecraft) was 612 hours.

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Despite a faltering battepy not expected to endure therigors of the lunar environment over an extended period, Surveyorcontinued to accept Earth commands and transmit TV picturesthroggh the second lunar sunset. It received and acted uponapproximately 120,000 commands during the mission.Commurnications with Surveyor I were re-establishedperiodically through January, 1967, but no TV pictures wereobtained after the July, 1966, activity. important Dopplerdata on the motion of the Moon was acquired during the final

months of Surveyor operations.On Feb. 22, 1967, at 12:24 a.m. EST, Surveyor I was photo-graphed on the surface of the Moon by Lunar Orbiter III.Surveyor II was launched on Sept. 20, 1966, toward SinusMedii in the center of the Moon. An attempt to perform themidcourse manuever was unsuccessful when one of the three liquidfuel vernier engines failed to fire. The thrust imbalancecaused the spacecraft to begin tumbling. Repeated attemptswere made to command all three engines to fire to regain controlof the spacecraft. When all attempts fai2ed it was decided

to perform a series of engineering experiments to obtain dataon various subsystems concluding with the firing of the mainretrorocket. The spacecraft impacted the Moon southeast of thecrater Copernicus at a velocity of nearly 6,000 miles per hour.Intensive investigation into possible causes of theSurveyor II failure by a team comprised of propulsion expertsfrom the Jet Propulsion Laboratory, Hughes Aircraft Co.,Thiokol Chemical Corp. and NASA did not result in the identifi-cation of the exact cause. As a result of this investigation,however, a number of changes in testing procedures were recOM-

mended for Surveyor C and subsequent spacecraft to providebetter diagnostic capability in the vernier propulsion systemduring preflight testing as well as during the mission. Thesechanges are designed to minimize the possibility of recurrenceof the Surveyor II problem.

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SURVEYOR C SPACECRAFTSpaceframe, Mechanisms and Thermal Control

The spaceframe of the Surveyor is a triangular aluminumstructure which provides mounting surfaces and attachmentsfor the landing gear, main retrorocket engine, vernier enginesand associated tanks, thermal compartments, antennas and otherelectronic and mechanical assemblies.The frame is constructed of thin-wall aluminum tubing,with the frame members interconnected to form the triangle.A mast, which supports the planar array high-gain antennaand single solar panel, is attached to the top of the spaceframe.The basic frame weighs less than 60 pounds and installationhardware weighs 23 pounds.The Surveyor stands about 10 feet high and, with itstripod landing gear extended, can be placed within a 14-footcircle. A landing leg is hinged to each of the three lowercorners of the frame and an aluminum honeycomb footpad is

attached to the outer end of each leg. An airplane-type shockabsorber and telescoping lock strut are connected to the frameso that the legs can be folded into the nose shroud duringlaunch.Blocks of crushable aluminum honeycomb are attached tothe bottom of the spaceframe at each of its three corners toabsorb part of the landing shock. Touchdown shock also isabsorbed by the footpads and by the hydraulic shock absorberswhidh compress with the landing load.Two omnidirectional, conical antennas are mounted on theends of folding booms which are hinged to the spaceframe. Thebooms remain folded against the frame during launch untilreleased by squib-actuated pin pullers and deployed by torsionsprings. The antenna booms are released only after the landinglegs are extended and locked in position.An antenna/solar panel positioner atop the mast supportsand rotates the planar array antenna and solar panel in eitherdirection along four axes. This freedom of movement allows theantenna to be oriented toward Earth and the solar panel towardthe Sun.

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SURVEYORSOLAR PANEL

OMNIDIRECTIONALANTENNA A

,- HIGH-GAIN ANTENNATHERMALLY CONTROLLED%, COMPARTMENT B

THERMALLY CONTROLLED C R BCOMPARTMENT A TV CAMERASTAR CANOPUSSENSOR

RADAR ALTITUDE-DOPPLER VELOCITY OMNIECTA NASENSOR O M I D R E T I N A

FOOTPA 3

FOOTPAD 2 / i VERNIER ENGINE 3CRUSHABLE VERNIER PROPELLANTPBLOCKRESSURIZING GAS

SOIL SAMPLER TANK (HELIUM)AUXILIARY BATTERYRETRO ROCKET NOZZLE

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Two thermal compartments house sensitive electronicapparatus for which active thermal control is needed through-out the mission. The equipment in each compartment is mountedon a thermal tray that distributes heat throughout the com-partment. An insulating blanket, consisting of 75 sheets ofaluminized Mylar, is sandwiched between each compartment'sinner shell and the outer protective cover. The tops of thecompartments are covered by mirrored glass thermal radiatorsto dissipate heat.Compartment A, which maintains an internal temperaturebetween 40 degrees and 125 degrees F., contains two radio re-

ceivers, two transmitters, the main battery, battery chargeregulator, aain power switch and some auxiliary equipment.Compartment B. kept between zero and 125 degrees F.,houses the central command decoder, boost regulator, centralsignal processor, signal processing auxiliary, engineeringsignal processor, and low data rate auxiliary.Both compartments contain sensors for reporting tempera-ture measurements by telemetry to Earth, and heater assembliesto maintain the thermal trays above their al.-"wable minimums.The compartments are kept below the 125-degree maximum withthermal swithces which provide a conductive path to the radiatingsurfaces for automatic dissipation of electrically generatedheat. Compartment A contains nine thermal switches and com-partment B, six. The thermal shell weight of compartment A is25 pounds, and compartment B, 18 pounds.Passive temperature control is provided for all equipment,not protected by the compartments, through the use of paintpatterns and polished surfaces.Twenty-nine pyrotechnic devices mechanically release orlock the mechanisms, switches and valves associated with theantennas, landing leg locks, roll actuator, retrorocket separa-

tion attachments, helium and nitrogen tanks, shock absorbersand the retromotor detonator. Some are actuated by command frodthe Centaur, and others are actuated by ground command.A solid propellant, spherical retrorocket fits within theceater cavity of the triangular frame and supplies the mainthrust for slowing the spacecraft on approach to the Moon.The unit is attached at bhree points on the spaceframe near thelanding leg hinges, with explosive nut separation points forejection after burnout. The motor case, made of high-strengthsteel and insulated with asbestos and rubber, is 36 inches indiameter. Including the molybdenum nozzle, the unfueled motorweighs 144 pounds. With propellant, the weight is about 1,444pounds, or more than 60 per cent of the total spacecraft weight.

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Electrical harnesses and cables interconnect the space-craft subsystems to provide correct signa. and power flow.The harness connecting the two thermal compartments is routedthrough a thermal tunnel to minimize heat loss from the com-partments. Coaxial cable assemblies, attached to the space-frame by brackets and clips, are used for high frequencytransmission.Electrical interface with the Centaur stage is establishedthrough a 51-pin connector mounted on the bottom of the space-frame between two of the landing legs. The connector mates

with the Centaur connector when the Surveyor is mounted tothe launch vehicle. It carries pre-separation commands fromthe Centaur programmer and can handle emergency commands fromthe blockhouse console. Ground power and prelaunch monitoralso pass through the connector.

Power Subsystem

The power sybsystem collects and stores solar energy,converts it to usable electric voltage, and distributes it tothe other spacecraft subsystems. The subsystem consists of thesolar panel, a main battery and an auxiliary battery, an auxi-liary battery control, a battery charge regulator, main powerswitch, boost regulator, and an engineering mechanisms auxiliary.

The solar panel is the spacecraft's primary power sourceduring flight and during operations in the lunar day. It consistsof 3,960 solar cells arranged on a thin, flat surface approxi-mately nine square feet in area. The solar cells are groupedin 792 separate modules and connected in series-parallel toguard against complete failure in the event of a single cellmalfunction.The solar panel is mounted at the top of the Surveyorspacecraft's mast. Wing-like, it is folded away during launchand deployed ly Earth-command after the spacecraft has been in-jected into the lunar transit trajectory.When properly oriented during flight, the solar panelcan supply about 89 watts, most of the power required for theaverage operating load of all on-board equipment.During operation on the lunar surface, the solar panel can

be adjusted by Earth-command to track the Sun within a fewlegrees, so that the solar cells remain always perpendicularto the solar radiation.

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In this lunar-surface mode, the solar panel Is designedto supply a minimum of 77 watts power at a temperature of 140degrees F., and a minimum of 57 watts at a temperature of 239degrees F.A 14-cell rechargeable, silver-zinc main battery is thespacecraft's power reservoir. It is the sole source of powerduring launch; it stores electrical energy from the solar panelduring transit and lunar-day operations; and it provides a

backup source to meet peak power requirements during both ofthose periods.Fully charged, the battery provides 3,800 watt-hoursat a discharge rate of 1.0 amperes. Battery output is approxi-mately 22 volts direct current for all operating and environ-mental conditions in temperatures from 40 degrees to 125 degreesF.The auxiliary battery is a non-rechargeable, silver-zincbattery contained in a sealed magnesium cannister. It providesa power backup for both the main battery and the solar panelunder peak power loading or emergency conditions.The battery has a capacity of from 800 to 1,000 watt-hours,depending upon power load and operating temperature.The battery charge regulator and the booster regulatorare the two power conditioning elements of the spacecraft'selectrical power subsystem.The battery charge regulator couples the solar panel tothe main battery for maximum conversion and transmission ofthe solar energy necessary to keep the main battery at fullcharge.It receives power at the solar panel's varying outputvoltage, and it delivers this power to the main battery at aconstant battery terminal voltage.The battery charge regulator includes sensing and logiccircuitry for automatic battery charging whenever battery voltagedrops below27 volts direct current. Automatic battery chargingalso maintains battery manifold pressure at approximately 65pounds per square inch.Earth-command may override the automatic charging func-tion of the battery charge regulator.

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The booster regulator unit receives unregulated powerfrom 17 to 27.5 volts direct current from the solar panel,the main battery, or both, and delivers a regulated 29 voltsdirec- c.uirrent to the spacecraft's three main power transmissionlines. ithese three lines supply all the spacecraft's powerneeds, except for a 22-volt unregulated line which servesheaters, switches, actuators, solenoids and electronic circuitswhich do not require regulated power or provide their ownregulation.

Telecomwnunicaticns

Communications equipment aboard Surveyor has three func-tions: to provide for transmission and reception of radio sig-nals; to decode commands sent to the spacecraft; and to selectand convert engineering and television data into a form suit-able for transmission,The first group includes the three antennas: one high-gain, directional antenna and two low-gain, omnidirectionalantennas, two transmitters and two receivers with transponderinterconnections. Dual transmitters and receivers are usedfor reliability.The high-gain antenna transmits 600-line television data.The low-gain antennas are designed for coramand reception andtransmission of other data including 200-line television datafrom the spacecraft. The low-gain antennas are each connectedto one receiver. The transmitters can be switched to eitherlow-gain antennas or to the high-gain antenna and can operateat low or high-power levels. Thermal control of the threeantennas is passive, dependent on surface coatings to keeptemperatures within acceptable limits.The command decoding group can handle up to 256 commandseither direct, (on-off) or quantitative (time-intervals). Eachincoming command is checked in a central command decoder whichwill reject a command, and signal the rejection to Earth, ifthe structure of the command is incorrect. Acceptance of acommand is also radioed to Earth. The command is then sent to

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Processing of most engineering data, (temperatures,voltages, currents, pressures, switch positions, etc.) ishandled by the engineering signal processor or the auxiliaryprocessor. There are over 200 engineering measurements ofthe spacecraft. None are continuously reported. There arefour commutators in ti engineering signal processor to permitsequential sampling of selected signals. The use of a commutatoris dependent on the type and amount of information requiredduring various flight sequences. Each commutator can be com-manded into operation at any time and at any of the five bitrates: 17.2, 137.5, 550, 1100 and 4,400 bits per second.Commutated signals from the engineering processors areconverted to 10-bit data words by an analog-to-digital conver-ter in the central signal processor and relayed to the transmitter.The low bit rates are normally used for transmissions over thelow gain antennas and the low power levels of the transmitters.

Propulsion

The propulsion system consists of three liquid fuelvernier rocket engines and a solid fuel retromotor.The vernier engines are supplied propellant by threefuel tanks and three oxidizer tanks. There is one paii oftanks, fuel and oxidizer, for each engine. The fuel and oxidi-zer in each tank is contained in a bladder. Helium storedunder pressure is used to deflate the bladders and force thefuel and oxidizer into the feed lines. Tank capacity is 170.3pounds each.The oxidizer is nitrogen tetroxide with 10 percent nitricoxide. The fuel is monomethylhydrazine monohydrate. An igni-tion system is not required for the verniers as the fuel andoxidizer are hypergolic, burning upon contact. The throttlerange is 30 to 104 pounds of thrust.The main retro is used at the beginning of the terminaldescent to the lunar surface and slows the spacecraft from anapproach velocity of about 6,000 miles per hour to approximately250 miles per hour. It burns an aluminum, ammonium-percholorateand polyhydrocarbon, case bonded composite type propellant witha conventional grain geometry.The nozzle has a graphite throat and a laminated plastic exitcone. The case is of high strength steel insulated with asbestosand silicon dioxide-filled buna-N rubber to maintain the vaseat a low temperature level during firing.

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Engine thrust varies from 8,ooo to 10,000 pounds overa temperature range of 50 to 70 degrees F. Passive thermalcontrol, insulating blankets and surface coatings will main-tain the grain above -',egrees F. It is fired by a pyrogenigniter. The main retro weighs approximately 1,444 pounds andis spherical shaped, 36 inches in diameter.

Flight Control SubsystemFlight control of Surveyor, control of its attitudeand velocity from Centaur separation to touchdown on the Moonsis provided by: primary Sun sensor, automatic Sun acquisitionsensor, Canopus sensor, inertial reference unit, altitudemarking radar, inertia burnout switch, radar altimeter andDoppler velovity sensors, flight control electronics, and threepairs of cold gas jets. Flight control electronics includes adigital programmer, gating and switching, logic and signaldata converter for the radar altimeter and Doppler velocity

sensor.The information provided by the sensors is processedthrough logic circuitry in the flight control electronics toyield actuating signals to the gas jets and to the three liquidfuel vernier engines and the solid fuel main retro motor.The Sun sensors provide information to the flight controlelectronics indicating whether or not they are illuminated bythe Sun. This information is used to order the gas Jets tofire and maneuver the spacecraft until the Sun sensors areon a direct line with the Sun. The primary Sun sensor consists

of five cadmium sulphide photo conductive cells. During flightSurveyor will continuously drift off of Sun lock in a cycle lessthan 0.2 t 0.3 degrees. The drift is cont kuously corrected bysignals from the primary sensor to the flight electronics order-ing the pitch and yaw gas jets to fire to correct the drift.Locking on to the star Canopus requires prior Sun lock-on.Gas jets fire intermittently to compensate for drift to main-tain Canopus lock-on and thus control spacecraft roll duringcruise modes. If star or Sun lock is lost, control is automati-cally switched from optical sensors to inertial sensors (gyros).The inertial reference unit is also used during missionevents when the optical sensors cannot be used. These eventsare the midcourse maneuver and descent to the lunar surface.This device senses changes in attitude and in velocity of thespacecraft with three gyros and an accelerometer. Informationfrom the gyros is processed by the control electronics to order

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-14-gas jet firing to change or maintain the desired attitude.During the thrust phases the inertial reference unit controlsvernier engine thrust levels, by differential throttling forpitch and yaw control and swiveling one vernier engine for rollcontrol. The accelerometer controls the total thrust level.

The altitude marking radar will provide the signal forfiring of the main retro. It Is located in the nozzle of theretromotor and i s ejected when the motor ignites. The radarwill generate a signal at about 60 miles above the lunar surface.The signal starts the programmer automatic sequence after a pre-determined period (directed by ground command); the programmerthen commands vernier and retro ignition and turns on the RadarAltimeter and Doppler Velocity Sensor (RADVS).The inertia burnout switch will close when the thrustlevel of the main retromotor drops below 3.5 g, generating asignal which is used by the programmer to command jettisoningof the retromotor and switching to RADVS control.Control of the spacecraft after main retro burnout isvested in the radar altimeter and Doppler velocity sensor.There are two radar dishes for this sensor. An altimeter/velo-city sensing antenna radiates two beams and a velocity sensingantenna two beams. Beams 1, 2, and 3 give vertical and trans-verse velocity. Beam 4 provides altitude or slant range infor-mation. Beams 1, 2, and 3 provide velocity data by summing inthe signal data converter of the Doppler shift (frequency shiftdue to velocity) of each beam. The converted range and velocitydata is fed to the gyros and circuitry logic which in turn con-trol the thrust signals to the vernier engines.The flight control electronics provide for processingsensor information into telemetry signals and to actuate space-craft mechanisms. It consists of control circuits, a commanddecoder and an AC/DC electronic conversion unit. The programmercontrols timing of main retro phase and generates precisiontime delays for attitude maneuvers and midcourse velocity cor-rection.The attitude Jets provide attitude control to the space-craft from Centaur separation to main retro burn. The gas Jetsystem is fed from a spherical tank holding 4.5 pounds of nitro-gen gas under high pressure. The system includes regulatingand dumping valves and three pairs of opposed gas Jets withsolenoid-operated valves for each jet. One pair of Jets is loca-

ted at the end of each of the three landing legs. The pair onleg number one control motion in a horizontal plane, impartingroll motion to the spacecraft. Pairs two and three controlpitch and yaw.

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Television

The Surveyor spacecraft carries one survey televisioncamera. The camera is mounted nearly vertically, pointed ata movable mirror. The mounting containing the mirror can swivel360 degreeu, and the mirror can tilt down to view a landing legto up above the horizon.The camera can be focused, by Earth command, from fourfeet to infinity.. Its iris setting, which controls the amountof light entering the camera, *an adjust automatically to thelight level or can be commanded from Earth. The camera has avariable focal length lens which can be adjusted to narrow angle,6.4 x 6.4 field of view, to wide angle, 25.4 x 25.4 field ofview.A focal plane shutter provides an exposure time of 150milliseconds. The shutter can also be commanded open for anindefinite length of time. A sensing device coupled to theshutter will keep it from opening if the light level is toointense. A too-high light level could occur from changes in the&rea of coverage by the camera, a change in the angle of mirror,

in the lens aperture, or Py changes in Sun angle. The samesensor controls the automatic iris setting. The sensing devicecan be overridden by ground command.The camera system can provide 200 or 600-line pictures.The 600-line pictures require that the high gain directionalantenna and the high power level of the transmitter are bothoperating. The 600-line mode provides a picture each 3.6. sec-onds and the 200 line mode every 61.8 seconds.A filter wheel can be commanded to one of four positionsproviding clear, colored or polarizing filters.Two flat beryllium mirrors are mounted on the spacecraftframe near leg number one to provide additional coverage ofthe area under the spacecraft for the television camera. Thelarger mirror is 10 inches x 9 inches; the smaller is 3i inchesx 91 inches.The large mirror provides a view of the lower portion ofcrushable block number three and the area under vernier enginenumber three. The small mirror provides a view of the areaunder vernier engine number two.The purpose is to provide pictures of the lunar soildisturbed by the spacecraft landing and the amount of damageto the crushable block itself.Principal television investigator is Dr. Ruga3e Shoemaker,U. S. Geological Survey.

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-15a-SURVEYOR SURVEY TV CAMERA

HOOD MIRROR

MIRROR AZIMUTH ELEVATIONDRIVE MOTOR DRIVE ASSEMBLY

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lb VIDICONRADIATORELECTRONICCONVERSIONUNIT

ELECTRICALCONNECTOR

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Surface Sampler Experiment

Payload of the Surveyor C spacecraft includes a surfacesampler mechanism designed to provide significant informationon the characteristics of the lunar surface.To be flown for the first time on the third Surveyormission and planned also for Mission D, the metal claw diggermay enable scientists to analyze the Moon's bearing strengthto a depth of about 18 inches by digging holes and furrows andmoving small amounts of lunar soil from one place to another.The device is a scoop about five inches long and two incheswide attached to an extendable arm hinged horizontally andvertically to the spacecraft. The surface sampler is attachedto the spaceframe in place of the downward-looking approach TVcamera which was flown on Surveyors I and II.The flexible arm, to which the scoop is rigidly attached,

is made up of tubular aluminum cross members which operatemechanically in a scissor fashion to extend or retract the scoop.The arm is spring-loaded and is held in its retracted or partiallyretracted position by a metal tape, one end attached to the scoopand the other wound on a motor spindle at the base. Extensionand retraction of the arm is controlled by commands to the motorto reel or unreel the tape. Maximum extension is about fivefeet from the spaceframe.Two other motors, which can be operated in either direction,will allow the arm to pivot 112 degrees in a horizontal arc andto elevate or lower the scoop over a range of some 40 inches

above to about 18 inches below a level lunar surface. Surfacearea available to the sampler totals about 24 square feet.A fourth motor, located in the scoop, opens and closesa two-by-four-inch door on the scoop. All four motors operateon 22 volts of unregulated direct current from the spacecraftbattery. They operate for either of two time periods, a singlecommand pulsing the motor for one-tenth of a second or for twoseconds. Selection of the motor to be operated, motor directionand the time period is made by ground command.The instrument will be used in conjunction with the survey

TV camera. The scoop will be positioned in view of the camera,then activated to perform picking, digging or trenching opera-tions. Visual data combined with a determination of the forcedeveloped during the digging is expected to indicate strength,texture and cohesive characteristics of the soil..-more-


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SURVEYOR SURFACE SAMPLER MOVEMENTS

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4- MaxeihtClIGGING AND A n *35 IN. 4/SCOOPING AREA i. J\, w\i(DOTTED OUTLINE)ABOUT 24 SO . FT,

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A single telemetry channel from the Surveyor will mcnitorthe electric current being drawn by the motor in operation.By using pre-flight calibration data, this measurement can beused in analyzing the force necessary to scrape or dig thesurface and break small rocks or clods.In the event of a camera failure, where the surfacesampler must be used in the blind, the force measurements will

be of some, but less value, in analyzing the operation of theinstrument. For maximum success of the experiment, the surfacesampler is dependent upon visual data from the TY camera.The scoop, arm, motors, and housing for the device totalabout .4 pounds. The instrument's electronics unit, locatedin a separate thermal-control compartment, weighs about 6.3pounds.Principal scientific investigator for the surface samplerexperiment is Dr. Ronald F. Scott of the California Instituteof Technology. The instrument was designed and built by the

Hughes Aircraft Company.Engineering Instrumentation

Engineering evaluation of the Surveyor flight will beaugmented by an engineering payload including an auxiliarybattery, auxiliary processor for engineering information, andinstrumentation consisting of extra temperature sensors, straingauges for gross measurements of vernier engine response toflight control commands and shook absorber loading at touchdown,and extra accelerometers for measurements of vernier engineresponse to flight control commands and shook absorber loadingat touchdown, and extra accelerometers for measuring structuralvibration during main retro burn.

The auxiliary battery will provide a backup for bothemergency power and peak power demands to the main batteryand the solar panel. It is not rechargeable.The auxiliary engineering signal processor provides twoadditional telemetry commutators for determining the performanceof the spacecraft. It processes the information in the same

manner as the engineering singal processor, providing additionalsignal capacity and redundancy.

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-18-ATLAS-CENTAUR LAUNCH VEHICLE

Primary objective of the Atlas-Centaur 12 launch vehicleis to inject the Surveyor C spacecraft on a lunar impacttrajectory with sufficient accuracy so that the midcoursecorrection required of the spacecraft is within its capabilityof 111.85 miles per hour. The Centaur second stage will executea retromaneuver after spacecraft separation to ensure that thevehicle and spacecraft are adequately separated.Surveyor C will be injected toward the Moon followingprimary boost by an Atlas, injection of the Centaur stage andspacecraft into a 100-statute mile Earth parking orbit, and finalinjection of the spacecraft following a variable-length coastphase. Depending on time of launch, the coast phase will varyfrom four to 25 minutes.This will be the first operational two-burn mission forthe Atlas-Centaur vehicle. Previously, Surveyors I and II weresuccessfully launched to the Moon using the single-burn, direct-

ascent method.Surveyor I was injected on its lunar-transfer trajectorywith such accuracy than the midcourse velocity correction re-quired by the spacecraft to land within ten miles of its pre-selected target was only about eight miles per hour. (Surveyorhas a maximum "lunar miss" correction capability of 111.85 mph.)Even without a midcourse correction, Surveyor I would havelanded only 250 miles from its target.The high-energy Centaur second stage demonstrated itscapability to perform two-burn, parking orbit missions last

October with the successful test flight of the AC-9 vehicle.That mission completed the Centaur vehicle development programand qualified the Centaur for operational use for both direct-ascent and parking orbit flights.In addition to supporting the Surveyor program, the Centaurvehicle is also scheduled to launch two Mariner spacecraft onMars fly-bys during 1969. Centaur was also recently designatedto launch the Orbiting Astronomical Observatory spacecraft andAdvanced Technology Satellites beginning in 1968.

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-19-LAUNCH VEHICLE CHARACTERISTICS

(All figures approximate)

Liftoff weight: 303,000 lbs.Liftoff height: 113 feetLaunch Complex: 36-BIrhunch Azimuth: Variable: 93-115 degrees

Atlas-D Booster Centaur StageWeight: 263,000 lbs. 37,80o lbs.Height: 75 feet (including 47 feet (withinterstage adapter) fairing)Thrust: 388leel lbs. (sea X0,000 lbs.

level) ?vacuum)Propellants: Liquid oxygen and Liquid hydrogenRP-1 and liquid oxygenPropulsion: MA-5 system (2- Two 15,000 lb.165,000 lb. thrust thrust RL-10 enginesengines,p 1-57,000,2-670)Velocity: 5,600 mph at BEC0 23,600 mph at7,900 mph at SECO injectionGuidance: Pre-programmed auto- Inertial guidancepilot through BECO

AC-12 consists of a modified Series D Atlas combined witha Centaur second stage. Both stages are 10 feet in diameterand are connected by an interstage adapter. Both the Atlasand Centaur stages rely on pressurization for structural in-tegrity.

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The Atlas first stage is 75 feet high, including theinterstage adapter, and uses a standard MA-5 propulsionsystem. It consists of two booster engines and a sustainerengine, developing 387,000 pounds of thrust. Two vernierengines of 670 pounds thrust each provide roll directionalcontrol.The Centaur second stage including the nose fairingis 47 feet long. It is powered by two improved RL-10 hydrogen-oxygen engines, designated RL-10 A-3-3. The RL-10 was thefirst hydrogen-fueled engine developed for the space programand is the forerunner of the larger J-2 and M-1 hydrogenengines, which develop 200,000 and 1,500,000 pounds thrust,respectively.The current Atlas-Centaur vehicle can launch about 2,350pounds on a two burn parking orbit ascent lunar trajectory.An improved Atlas, called a Standardized Launch Vehicle (SLV-3C),used in combination with Centaur will increase this capabilityto about 2,600 pounds for two burn parking orbit ascent lunarmissions.Modifications to the vehicle to increase its payloadcapability include lengthening of the Atlas by four feet, whichwill increase its total propellant capacity by some 20,000pounds, and uprating of the Atlas booster and sustainer engines,which will increase the booster thrust from 388,ooo to 395,OOOpounds.The SLV-3C is scheduled to be used initially on the AC-13mission.Centaur carries insulation panels and a nose fairing

which are jettisoned after the vehicle leaves the Earth's atmos-phere. The insulation panels, weighing about 1,200 pounds,surround the second stage hydrogen tanks to prevent the heatof air friction from causing excessive boil-off of liquidhydrogen during flight through the atmosphere. The nose fair-Ing protects the payload from this same heat environment.

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A!IAB-CINTAU FLIOUM 1UNENOINL . AIaTMDI, SUNCE RAUE, vImCfEVUFW STATMT NIIZS STATMT N!LES MPH

Liftoff 0 0 0 0Booster &gine Cutoffand Booster Jettison 143 37 44 5,600Jettison Insulation

Panels 177 57 88 6,200Jettison Neoe Fairing 204 70 128 6,800Sustainer rgine Cutoffand Atlas separation 236 85 183 7,900Centaur engine start 248 90 204 7,900Centaur engine cutoff 575 105 1,079 16,500 roCoast in Earth orbit - - -Centaur seoond burn 2,077 105 7,018 36,50oCentaur engine cutoff 2,1185 113 7,515 23,600Spacecraft separation 2,253 144 7,890 23,600Start Centaur re -orientation 2,258 147 7,920 23,600Start Centaur retro-thrust 2,493 445 9,116 22,800*Noninal times of events are directly influenced bythe time of launch which determines the parking orbitduration. Nominal times given are fo r a 25-minute parking orbit.


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TRACKING AND COMMUNICATIONThe flight of the Surveyor spacecraft from injection tothe end of the mission will be monitored and controlled bythe Deep Space Network (DSN) and the Space Flight OperationsFacility (SFOF) operated by the Jet Propulsion Laboratory.Some 300 persons will be involved in Surveyor flightmonitoring and control during peak times in the mission. Onthe Surveyor I flight more than 100,000 ground commands were

received and acted on by the spacecraft during flight andafter the soft landing.The Deep Space Network consists of six permanent spacecommunications stations in Australia, Spain, South Africa andCalifornia; a spacecraft monitoring station at Cape Kennedy;and a spacecraft guidance and a command station at AscensionIsland in the South Atlantic.The DSN facilities assigned to the Surveyor project arePioneer at Goldstone, Calif; Robledo, Spain; Tidbinbilla inthe Canberra complex, Australia; and Ascension Island.The Goldstone facility is operated by JPL with theassistance of the Bendix Field Engineering Corp. TheTidbinbilla facility is operated by the Australia Departmentof Supply. The Robledo facility is operated by JPL under anagreement with the Spanish government and the support ofInstituto Nacional de Teonica Aeroespacial (INTA) and theBendix Field Corp. The Ascension Island DSN facility isoperated by JPL with Bendix support under a cooperative agree-ment between the United Kingdom and the U.S.The DSN uses a ground communications system for operationalcontrol and data transmission between these stations. Theground communicaticns system is a part of a larger net (NASCOV)which links all of the NASA stations around the world. Thisnet is under the technical direction of NASA's Goddard SpaceFlight Center, Greenbelt, Md.The DSN supports The Surveyor flight in tracking thespacecraft, receiving telemetry from the spacecraft, and sendingit commands. The DSN renders this support to all of NASA'sunmanned lunar and planetary spacecraft from the time they areinjected into planetary orbit until they complete their

missions.Stations of the DSN receive the spacecraft radio signals,amplify them, process them to separate the data from thecarrier wave and transmit required portions of the data tothe command center via high-speed data lines, radio links, and

teletype. The stations are also linked with the center by voicelines. All incoming data are recorded on magnetic tape.-more-


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The information transmitted from the DSN stations to theSFOF is fed into large scale computer systems which translatethe digital code into engineering units, separate informationpertinent to a given subsystem on the spacecraft, and drivedisplay equipment in the SFOF to present the information tothe engineers on the project. All incoming data are againrecorded in the computer memory system and are available ondemand.Equipment for monitoring television reception fromSurveyor is located in the SFOF.Some of the equipment is designed to provide quick-lookinformation for decisions on commanding the camera to changeiris settings, change the field of view from narrow angle towide angle, change focus, or to move the camera eitherhorizontally or vertically. Television monitors display thepicture being received. The pictures are received line byline and each line is held on a long persistence televisiontube until the picture is complete. A special camera system

produces prints of the pictures for quick-look analysis.Other equipment will produce better quality pictures fromnegatives produced by a precision film recorder.Commands to operate the c-mera will be prepared inadvance on punched paper tape Pld forwarded to the stationsof the DSN. They will be tra!.,-,ilitted to the spacecraft fromthe DSN station on orders from the SFOF.Three technical teams support the Surveyor televisionmission in the SFOF: one is responsible for determining thetrajectory of the spacecraft including determination of launchperiods and launch requirements, generation of commands forthe midcourse and terminal maneuvers; the second is responsiblefor continuous evaluation of the condition of the spacecraftfrom engineering data radioed to Earth; the third is responsiblefor evaluation of data regarding the spacecraft and forgenerating commands controlling spacecraft operations.

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TRAJECTORYThe determination of possible launch days, specific timesduring each day and the Earth-Moon trajectories for the Sur-veyor spacecraft are based on a number of factors, or contraints.A primary constraint is the time span during each day theSurveyor can be launched -- the launch window -- which is de-termined by the requirement that the launch site at launch timeand the Moon at arrival time be contained in the Earth-Moontransfer orbit plane. With the launch site moving eastward asthe Earth revolves, acceptable conditions occur only once eachday for a given plane. However, by altering the plane as a re-sult of changing the launch azimuth, or direction of launchfrom the launch site, between an allowable 78 to 115 degrees,East of North, the launch window can be extended up to as muchas four hours.The launch azimuth constraint of 78 to 115 degrees is im-

posed by the range safety consideration of allowing the initiallaunch phase only over the ocean, not over land masses.The time of flight, or the time to landing, about 61-65hours, is determined by the constraint placed upon the trajec-tory engineer that Surveyor must reach the Moon during the view-ing period of the prime Deep Space Net station at Goldstone inthe California Mojave Desert.Landing sites are further limited by the curvature of theMoon. The trajectory engineer cannot pick a site, even if itfalls within the acceptable band, if the curvature of the Moon

will interfere with a direct communication line between thespacecraft and the Earth.Two other factors in landing site selection are smoothnessof terrain and a requirement for Surveyor to land, in areas se-lected for the Apollo manned lunar mission.Thus the trajectory engineer must tie together the launchcharacteristics, the landing site location, the declination ofthe Moon and flight time, in determining when to launch, inwhich direction, and at what velocity.His chosen trajectory also must not violate constraints onthe time allowable that the Surveyor can remain in the Earth'sshadow. Too long a period can result in malfunction of com-ponents or subsystems. In addition, the Surveyor must not re-main in the shadow of the Moon beyond given limits.

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SURVEYOR TRAJECTORIES TO THE MOON

PARKING ORBIT TRAJECTORYON DIRECT ASCENT LAUNCH WITH 2 FIRINGS OF SECOND STAGE ENGINES,END OF SECOND STAGE ENGINES' AND COAST PHASE BETWEEN, SURVEYOR CANSINGLE FIRING ALWAYS ENDS REACH ANY MOON POSITION ABOVE OR BELOWNEAR CAPE ABOVE EQUATOR EARTH'S EQUATOR

DIRECT ASCENT TRAJECTORY*/ / WITH SINGLE FIRING OF SECOND STAGE ENGINES/ /-,,5 s /SURVEYOR CAN REACH MOON ONLY WHEN MOONff r IS BELOW EARTH'S EQUATOR

COAST PHASE'I/ / ' a /

ON PARKING ORBIT LAUNCH '- /END OF SECOND FIRING OF -SECOND STAGE ENGINES CANOCCUR BELOW EQUATOR BYINCREASING COAST TIMEBETWEEN FIRINGS

DOTTED LINES SHOW MAXIMUM AMOUNT DIRECT ASCENT -TRAJECTORY CAN BE ADJUSTED TO REACH DIFFFRENT ---MOON POSITIONS-A-

*EARLY SURVEYORS WILL BE LAUNCHED ON DIRECTASCENT TRAJECTORIES


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The velocity of the spacecraft when it arrives at the Moonmust also fall within defined limits. These limits are definedby the retrorocket capability. The velocity relative to theMoon is primarily correlated with the flight time and the Earth-Moon distance for each launch day.So, a further requirement on the trajectory engineer is theamount of fuel available to slow the Surveyor from its lunar ap-proach speed of 6,000 mph to nearly zero velocity,13 feet above

the Moon's surface. The chosen trajectory must not yield velo-cities that are beyond the designed capabilities of the space-craft propulsion system.Also included in trajectory computation is the influence onthe flight path and velocity of the spacecraft of the gravita-tional attraction of primarily the Earth and Moon and to a lesserdegree the Sun, Mercury, Venus, Mars, and Jupiter.It is not expected that the launching can be performed withsufficient accuracy to impact the Moon in exactly the desiredarea. The uncertainties involved in a launch usually yield a

trajectory or an injection velocity that vary slightly from thedesired values. The uncertainties are due to inherent limita-tions in the guidance system of the launch vehicle. To compen-sate, lunar and deep space spacecraft have the capability of per-forming a midcourse maneuver of trajectory correction. To alterthe trajectory of a spacecraft it is necessary to apply thrust,or energy, in a specific direction to change its velocity. Thetrajectory of a body at a point in space being basically deter-mined by its velocity.For example, a simple midcourse might involve correcting atoo high injection velocity, To correct for this the spacecraft

would be commanded to turn in space until its midcourse engineswere pointing in its direction of travel. Thrust from the en-gines would slow the craft. However, in the general case themidcourse is far more complex and will involve changes both invelocity and its direction of travel.A certain amount of thrust applied in a specific directioncan achieve both changes. Surveyor will use its three liquidfuel vernier engines to alter its flight path in the midcoursemaneuver. It will be commanded to roll and then to pitch or yawin order to point the three engines in the required direction.The engines then burn long enough to apply the change in velocity

required to alter the trajectory.The change in the trajectory is very slight at this pointand a tracking period of about 20 hours is required to determinethe new trajectory. This determination will also provide the datarequired to predict the spacecraft's angle of approach to theMoon, time of arrival, and its velocity as it approaches the Moon.

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ATLAS-CENTAUR 12/SURVEYOR C FLIGHT PLANSurveyor C will be launched by Atlas-Centaur 12 fromCape Kennedy Complex 36B in the launch vehicle's firstoperational mission involving two burns of the Centaursecond stage.

Launch Periods

Arrival Time Off-VerticalLaunch Window Window IncidenceDate Oen Close rate Open Close Angle17 01:24 04:09 19 19:o6 22:o6 26018 03:10 05:43 20 20:03 23:33 27019 04:55 07:15 21-22 21:24 00:39 27020 o6:40 o8:45 22-23 22:24 01:12 25021 08:07 lo:16 23-24 23:25 01:14 230

Atlas PhaseAfter liftoff, AC-12 will rise vertically for the first15 seconds, then roll to the desired flight plane azimuthof between 93 and 115 degrees. During booster engine flight,the vehicle is steered by the Atlas autopilot.After 143 seconds of booster flight, the booster engines

are shut down (BECO) and Jettisoned. The Centaur guidancesystem then takes over flight control. The Atlas sustainerengine continues to propel the AC-12 vehicle to an altitudeof about 85 miles. Prior to sustainer engine shutdown, thesecond stage insulation panels are Jettisoned, followedby the nose fairings.The Atlas and Centaur stages are then separated by anexplosive, shaped charge and retrorockets mounted on theAtlas.

Centaur PhaseCentaur's hydrogen engines are then ignited for a planned327-second burn. This will place Centaur and the Surveyorspacecraft into a 100-mile Earth parking orbit.As Centaur's engines are shut down and the coast phase

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SURVEYOR FLIGHT PROFILE

SEPARATION ATLAUNCH PLUS /

CANOPUS ACQUISITIONABOUT LAUNCH PLUS 6 HRSCOMPLETES CRUISE ATTITUDE PRE-RETRO MANEUVERSTABILIZATION 30 MIN. BEFORE LANDINGSUN ,

SUN ACQUISITION |ABOUT LAUNCH STAR 63 HR SPLUS 1 HR CANOPUS / \/ I SUN AND CANOPUS REACQUISITION /IMMEDIATELY AFTER MIDCOURSEMIDCOURSE CORRECTION CORRECTIONABOUT LAUNCH PLUS 15 HRS 48 H2S

,024 HRS

MOONAT LAUNCH


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-27-begins, two 50-pound-thrust hydrogen-peroxide rockets arefired to settle the propellants.

Two hydrogen-peroxide ullage rockets, each with threepounds thrust, are then fired continuously during the coastperiod to retain the propellants in the lower part of thetanks.During the coast period in Earth orbit, control of

Centaur will be accomplished using two clusters of 3.5 andsix-pound thrust hydrogen-peroxide rockets.About 40 seconds before Centaur's second burn, thetwo 50-pound thrusters are again used to insure properpropellant settling.Once Centaur is in an accurate position to Inject theSurveyor toward the Moon, the hydrogen-fueled main enginesare ignited for an approximate 107-second burn. The second-burn command and duration of the burn are determined byCentaur's inertial guidance system, as are all command and

steering functions following Atlas booster engine cutoff andj ettison.Separation

The Surveyor spacecraft is separated from Centaur andinjected toward the Moon.Following spacecraft separation, the Centaur vehiclewill perform a 180-degree reorientation maneuver, using itsattitude control system.Centaur's velocity is then changed by retro-thrusting.The thrust for this maneuver is produced by two 50-poundhydrogen-peroxide thrusters as well as by 'blowing" residualpropellants through Centaur's main engines.As a result of this retromaneuver the Centaur and thespacecraft will be separated by at least 200 statute miles,five hours after launch.The Centaur vehicle will continue in a highly ellipticalEarth orbit with a period ranging from eight to 11 days.

First Surveyor EventsShortly after Centaur engine shutdown, the programmercommands Surveyor's legs and two omnidirectional antennasto extend and orders the spacecraft's transmitter to high power.After Surveyor separates from the Centaur an automatic

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command is given by the spacecraft to fire explosive boltsto unlock the solar panel. A stepping motor then moves thepanel to a prescribed position. Solar panel deployment canalso be commanded from the ground if the automatic sequencefails.Surveyor will then perform an automatic Sun-seeking man-euver to stabilize the pitch and yaw axes and to align itssolar panel with the Sun for conversion of sunlight to elec-tricity to power the spacecraft. Prior to this event thespacecraft main battery is providing power.The Sun acquisition sequence begins immediately afterseparation fvom Centaur and simultaneously with the solar paneldeployment. The nitrogen gas jet system, which is activatedat separation, will first eliminate random pitch, roll andyaw motions resulting from separation from Centaur. Then asequence of controlled roll and yaw turning maneuvers iscommanded for Sun acquisition.Sun sensors aboard Surveyor will provide signals to theattitude control gas jets to stop the spacecraft when it ispointed at the Sun. Once locked on the Sun, the gas jetswill fire intermittently to control pitch and yaw attitude.Pairs of attitude control jets are located on each of the threelanding legs of the spacecraft.In the event the spacecraft does not perform the Sunseeking maneuver automatically, this sequence can be com-manded from the ground.The next critical step for Surveyor is acquisition ofits radio signal by the Deep Space Net tracking stations atAscension Island and Johannesburg, South Africa, the first

DSN stations to see Surveyor after launch.It is critical at this point to establish the communi-cations link with the spacecraft to receive telemetry toquickly detexmaine the condition of the spacecraft, for com-mand capability to assure control, and for Doppler measure-ments from which velocity and trajectory are computed.The transmitter can only operate-at high power forapproximately one hour without overheating. It is expected,however, that the ground station will lock on to the space-craft's radio signal within 40 minutes after launch and if

overheating is indicated, the transmitter can be commandedto low power.The next major spacecraft event after the Sun has beenacquired is Canopus acquisition. Locking on the starCanopus provides a fixed inertial reference for the roll orienta-tion.

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Canopus AcquisitionCanopus acquisition will be commanded from the groundabout six hours after launch. The gas Jets will fire to rollthe spacecraft at 0.5 degree per second. When the sensorsees the predicted brightness of Canopus (the brightest starin the Southern Hemisphere) it will order the roll to stopand lock on the star. The brightness of the light sourceit is seeing will be telemetered to Earth to verify thatit is locked on Canopus.Verification can also be provided by a grournd command

ordering a 360 degree roll and the plotting of each light sourcethe sensor sees that is in the sensitivity range of the sensor.(The sensor will ignore light levels above and below givenintensities.) This star map can be compared with a map pre-pared before launch to verify that the spacecraft is locked onCanopus.Now properly oriented on the Sun and on Canopus, Sur-veyor is in the coast phase of the transit to the Moon.Surveyor is transmitting engineering data to Earth andreceiving commands via one of its omnidirectional antennas.Tracking data is obtained from the pointing direction of

ground antenna and observed frequency change (Doppler).The solar panel is providing electrical power andadditional power for peak demands is being provided by one oftwo batteries aboard. The gas jets are firing intermittentlyto keep the craft aligned on the Sun and Canopus.The engineering and tracking in'ormatitn is receivedfrom Surveyor at one of the stations of the Deep Space Net,The data is communicated to the Space Flight OperationsFacility (SFOF) at the Jet Propulsion Laboratory in Pasa-dena where the flight path of the spacecraft is carefully

calculated and the condition of the spacecraft continuouslymonitored.Midcourse Maneuver

Tracking data will be used to determine how large atrajectory correction must be made to land Surveyor in thegiven target area. This trajectory correction, called themidcourse maneuver, is required because of many uncertain-ties in the iaunch operation that prevent absolute accuracyin placing a spacecraft on a trajectory that will interceptthe Moon precisely at the desired landing point.The midcourse maneuver is timed to occur over the Goldstonestation of the DSN in the Mojave Desert, the tracking stationnearest the SFOF at JPL.

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SURVEYOR MIDCOURSE CORRECTION

CRUISE ATTITUDE

YAW (OR PITCH) TURN

CD CANOPUS ,-SUN AN D CANOPUSREACQUISITIONROLL TURN

VERNIER ENGINES BURN colp 4 '


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-30-The thrust for the midcourse maneuver will be provided bythe spacecraft's three liquid fuel vernier engines. Total thrustlevel is controlled by an accelerometer at a constant accel-eration equal to 0.1 Earth g (3.2 ft/sec/sec). Pointingerrors are sensed by gyros which can cause the individualengines to change thrust level to correct pitch and yawerrors and swivel one engine to correct roll errors.Flight controllers determine the required trajectorychange to be accomplished by the midcourse maneuver. inorder to align the engines in the proper direction to applythrust to change the trajectory, or flight path, Surveyor willbe commanded to roll, then pitch or yaw to achieve thisalignment. Normally, two maneuvers are required, a roll-pitchor a roll-yaw.The duration of the first maneuver is radioed to thespacecraft, stored aboard and re-transmitted back to Earthfor verification. Assured that Surveyor has received theproper information, it is then commanded to perform thefirst maneuver. When completed, the second maneuver ishandled in the same fashion. With the spacecraft now alignedproperly in space, the number of seconds of required thrust is

transmitted to the spacecraft, stored, verified and thenexecuted.In the event of a failure of the automatic timer aboardthe spacecraft which checks out the duration of each maneuverturn and firing period, each step in the sequence can beperformed by carefully timed ground commands.After completion of the midcourse maneuver, Surveyorreacquires the Sun and Canopus. Again Surveyor is in thecruise mode and the next critical event will be the terminalmaneuver.

Terminal SequenceThe first step starts at about 1,000 miles above theMoon's surface. The exact descent maneuvers will depend onthe flight path and orientation of the Surveyor with respectto the Moon and the target area. Normally they will be aroll followed by a yaw or a pitch turn. As in the midcoursemaneuver, the duration times of the maneuvers are radioedto the spacecraft and the gas jets fire to execute the re-quired roll and pitch and yaw. The object of the maneuveris to align the main retro solid rocket with the descent

path. To perform the maneuvers, the spacecraft willbreak its lock on the Sun. nd Canopus. Attitude controlwill be maintained by inertial sensors. Gyros will sensechanges in the attitude and order the gas jets to fire to-more-


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SURVEYOR TERMINAL DESCENTTO LUNAR SURFACEC S A E(Approximate Altitudes and Velocities Given)

PRE-RETRO MANEUVER 30 MIN.BEFORE TOUCHDOWN ALIGNS _MAIN RETRO WITH FLIGHT PATH

MAIN RETRO START BY ALTITUDEMARKING RADAR WHICH EJECTSFROM NOZZLE, CRAFT STABILIZEDBY VERNIER ENGINES AT52 MI. ALTITUDE, 5,900 MPH

t MAIN RETRO BURNOUT AND EJECTION,VERNIER RETRO SYSTEM TAKEOVER AT37,000 FT, 400 MP H

, I

VERNIER ENGINES SHUTOFF -.AT 14 FT, 3'1/ MP H

j'~

- 'TOUCHDOWN AT 8 MP H

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maintain the correct attitude until the retror6cket isignited.With the spacecraft properly aligned, the altitude mark-ing radar will be activated, by ground command, at approximately200 miles above the Moon's surface. All subsequent terminalevents will be automatically controlled by radars and the flightcontrol programmer. The auxiliary battery will be connectedto help the main battery supply the heavy loads required during

descent.At approximately 60 miles' slant range from the Moon'ssurface, the marking radar starts the flight control program-mer clock which then counts down a previously stored delaytime and then commands ignition of the solid propellant mainretro and the three liquid fueled, throttleable vernier engines.The vernier engines maintain a constant spacecraft attitude dur-ing main retro firing in the same manner as during midcoursethrusting.The spacecraft will be traveling at approximately 6,000

miles-per-hour. The main retro will burn out in 40 secondsat about 25,000 feet above the surface after reducing thevelocity to about 250 miles-per-hour. The casing of the mainretro is separated from the spacecraft, on command from theprogrammer 12 seconds after burnout, by explosive bolts andfalls free.After burnout the flight control programmer will controlthe thrust level of the vernier engines until the Radar Alti-meter and Doppler Velocity Sensor (RADVS) locks up on its returnsignals from the Moon's surface.Descent will then be controlled by the RADVS and the vernierengines. Signals from RADYS will be processed by the flightcontrol electronics to throttle the three verftier engines re-ducing velocity as the altitude decreases. At 13 feet above thesurface, Surveyor will have been slowed to three miles per hour.At this point the engines are shut off and the spacecraft freefalls to the surface.Immediately after landing, flight control power isturned off to conserve battery power.

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Post-landing Events

Of prime interest to the engineers who designed Surveyorwill be the engineering telemetry received during the descentand touchdown. Touchdown will be followed by periods of engin-eering telemetry to determine the condition of the spacecraft.Then a series of wide angle, 200-line television pictures willbe taker.The solar panel and high gain planar array antenna willthen be aligned with the Sun and Earth, respectively. If thehigh-gain antenna is successfully operated to lock on Earth,transmission of 600-line television pictures will begin. Ifit is necessary to operate through one of the low-gain, omni-directional antennas, additional 200-line pictures will betransmitted.The lifetime of Surveyor on the surface will be determinedby a number of factors such as the power remaining in thebatteries in the event that the Sun is not acquired by the solar

panel and spacecraft reaction to the intense heat of the lunarday and the deep cold of the lunar night.-more-


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ATLAS-CENTAUR AND SURVEYOR TEAMS

NASA HEADQUARTERS, WASHINGTON. D.C.Dr. Homer E. Newell Associate Administrator forSpace Science andApplicationsRobert F. Garbarini Deputy Associate Administrator

for Space Science andApplicationsOran W. Nicks Director, Lunar and PlanetaryProgramsBenjamin Milwitsky Surveyor Program ManagerV. L. Johnson Director, Launch Vehicle andPropulsion ProgramsT. B. Norris Centaur Program ManagerJET PROPULSION LABORATORY, PASADENA, CALIF.Dr. William H. Pickering DirectorGen. A. R. Luedecke Deputy DirectorHoward H. Haglund Surveyor Project ManagerKermit S. Watkins Assistant Project Manager forSurveyor OperationsRobert G. Forney Surveyor Spacecraft SystemManagerDr. Leonard Jaffe Project ScientistDEEP SPACE NETWORKDr. Eberhardt Rechtin Assistant Laboratory Directorfor Tracking and Data Ac-quisition, JPLDr. Nicholas A. Renzetti Surveyor Tracking and Data

Systems Manager, JPLW. E. Larkin JPL Engineer in Charge,

Goldstone-more-


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J. Buckley Pioneer Station Manager,GoldstoneR. J. Fahnestock JPL DSN Resident in AustraliaR. A. Leslie Tidbinbilla Station Mana(gerPhil Tardani JPL DSN Resident in SpainDonald Meyer Robledo Station ManagerAvron Bryan Ascension Station ManagerLEWIS RESEARCH CENTER, CLEVELAND. 0.Dr. Abe Silverstein DirectorDr. S. C. Himmel Assistant Director for LaunchVehiclesEdmund R. Jonash Centaur Project ManagerKENNEDY SPACE CENTER, FLA.Dr. Kurt R. Debus DirectorRobert H. Gray Director of Unmanned LaunchOperationsJohn D. Gossett Chief, Centaur OperationsPRINCIPAL SCIENTIFIC INVESTIGATORSDr. Eugene Shoemaker TelevisionU.S. Geological SurveyDr. Ronald F. Scott Surface SamplerCalifornia Institute ofTechnologyHUGHES AIRCRAFT COMPANY, CULVER CITY, CALIF.Dr. Robert L. Roderick Surveyor Program ManagerAseistant Manager -- LunarProgramsRobert E. Sears Associate Program ManagerRichard R. Gunter Assistant Program Manager

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GENERAL DYNAMICS/CONVAIR, SAN DIEGO, CALIF.Grant L. Hansen Vice President, Launch VehicleProgramsPRATT AND WHITNEY AIRCRAFT DIVISION OF UNITED AIRCRAFT CO..WEST PAI4 BEACH, FLA.Richard Anchutze RL-10 Engine Project ManagerHONEYWELL, INC., ST. PETERSBURG, FLA.R. B. Foster Centaur Guidance ProgramManager

SURVEYOR/ATLAS -CENTAUR SUBCONTRACTORSAiResearch Division Ground Support EquipmentGarrett CorporationTorrance, Calif.Airite Nitrogen TanksEl Segundo, Calif.Airtek Propellant TanksFansteel Metallurgical Corp.Compton, Calif.Ampex Tape RecorderRedwood City, Calif.Astrodata Deconmutators and SubcarrierAnaheim, Calif. Discriminator SystemsBell & Howell Company Camera LensChicago, Ill.Bendix Corporation Landing Dynamics StabilityProducts Aerospace Division StudySouth Bend, IndianaBorg-Warner Tape RecorderSanta Ana, Calif.Brunson Optical Alignment EquipmentKansas City, KansasCarleton Controls Helium RegulatorBuffalo, New York

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Eagle-Picher Company Auxiliary BatteriesJoplin, Mo.Electric Storage Battery Main BatteriesRaleigh, N.C.Electro-Development Corp. Strain Gage ElectronicSeattle, Wash.Electro-Mechanical Research DecommutatorsSarasota, Fla.Endeveo Corporation AccelerometersPasadena, Calif.General Electro Dynamics Vidicon TubesGarland, Tex.General Precision, Inc. Spacecraft TV Ground DataLink Group Handling SystemPalo Alto, Calif.Heliotek Solar ModulesSylmar, Calif.Hi-Shear Corp. Separation DeviceTorrance, Caiif.C. G. Hokanson Mob. Temperature ControlSanta Monica, Calif. UnitHolex SquibsHollister, Calif.Honeywell Tape Recorder/ReproducerLos Angeles, Calif.Kearfott Division GyrosGeneral Precision Co.Little Falls, N.J.Kinetics Main Power SwitchSolana Beach, Calif.Lear Siegler T.V. Photo RecorderSanta Monica, Calif.Menasco Gas TanksLos Angeles, Calif.

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Metcom Magnetron AssemblySalem, Mass.Motorola, Inc. Subcarrier OscillatorsMilitary Electronics DivisionScottsdale, Ariz.National Water Lift Co. Landing Shock AbsorberKalamazoo, Mich.Northrop/Norair Landing GearHawthorne, Calif.Ryan Aeronautical Co. Radar Altitude Doppler VelocitySan Diego, Calif. SensorSanborn L. F. OscillographWaltham, Mass.Scientrific-Atlanta System Test StandAtlanta, Ga.Singer-Metrics F. M. CalibratorBridgeport, Mass.Telemetrics SimulatorSanta Ana, Calif.Thiokol Chemical Corp. Main Retro EngineElkton DivisionElkton, Md.Thiokol Chemical Corp. Vernier Propulsion SystemReaction Motors DivisionDenville, N. J.Tinsley Laboratories, Inc. Spacecraft MirrorsBerkeley, Calif.United Aircraft Corp. Subcarrier OscillatorNorden DivisionSouthhampton, Pa.Vector Subcarrier OscillatorSouthhampton, Pa.

AtlasRocketdyne Division of MA-5 Propulsion SystemNorth American Aviation, Inc.Canoga Park, Calif.

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Thiokol Chemical Corp. LOX and Fuel Staging ValvesReaction Motors DivisionDenville, N. J.Hadley Co., Inc. Valves, Regulators and

Dis connect Coupling 4Fluidgenics, Inc. RegulatorsGeneral Precision, Inc. Displacement GyrosKearfott DivisionSan Marcos, CalifHoneywell, Inc. Rate GyrosAeronautical DivisionFifth Dimension, Inc. CommutatorsBendix Corp. Telepaks and OscillatorsBendix Pacific DivisionFairchild-Hiller LOX Fuel and Drain ValvesStratos Western DivisionBourns, Inc. Transducers and PotentiometersWashington Steel Co. Stainless SteelWashington, Pa.General Dynamics Insulation Panels and NoseFort Worth Division FairingFort Worth, Tex.Pesco Products Division of Boost Pumps for RL-10 EnginesBorg-Warner Corp.Bedford, 0.Bell Aerosystems Co. of Attitude Control SystemBell Aerospace Corp.Buffalo, N. Y.Liquidometer Aerospace Division Propellant Utilization SystemSimmonds Precision ProductsInc.Long Island, N.Y.General Precision, Inc. Computer for Inertial GuidanceKearfott Division SystemSan Marcos, Calif.

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Goodyear Aerospace Division Handling TrailerGoodyear Tire and Rubber Co.Akron, 0.Systems and Instruments Div. DestructorsBullova Watch Co.Flushing, N. Y.Consolidated Control Corp. Safe and Amn InitiatorEi Segundo, Calif.Borg-Warner Controls Division InverterBorg-Warner Corp.Santa Ana, Calif.Sippican Corp. Modules fo r Propellant Utili-Marion, Mass. zation SyztemGeneral Electric Co. 'rurbineLynn, Mass.

Vickers Division of Hydraulic PumpsSperry Raad Corp.Troy, Mich.EdclMf instruments, Inc. Transducers and SwitchesMonrovia, Calif.Rosemount Engineering Co. TransducersMinneapolis, Minn.Scientific Data Systems ComputersSanta Monica, Calif.W. 0. Leonard, Inc. Hydrogen and Oxygen Vent Val'iesPasadena, Calif.

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Surveyor C Press Kit