Pageos Press Kit

8/8/2019 Pageos Press Kit

1/24


2/24

cNATIONAL AERONAUTICS AND SPACE ADMINISTRATION TELS WO 2-4155E W A WASHINGTON, D.C. 20546 WO 3-6925FOR RELEASE: SUNDAY

June 19, 1966RELEASE NO: 66-150

PAGEOS SATELLITE

TO GIRDLE GLOBEFOR EARTH MAPPING

A 100-foot "balloon" satellite, designed to obtain

information for precision mapping of the Earth's surface,

will be launched by the National Aeronautics and Space

Administration no earlier than June 23.The aluminum-coated Passive Geodetic Earth-Orbiting

Satellite (similar to Echo I launched Aug. 12, 1960)will be photographed by a network of 41 ground observingsites around the world. It will be called PAGEOS I if

successfully placed in orbit.A Thrust-Augmented Thor-Agena-D launch vehicle will

be used to boost the inflatable sphere satellite into acircular, polar orbit about 24600 miles above Earth. Itwill be launched in a southeasterly direction from theWestern Test Range, Cal. with an inclination of about87 degrees to the equator.

- more - 6/14/66


3/24

-2-

PAGEOS will carry no instruments. By reflecting sun-light, the satellite will provide an orbiting point sourceof light to be Photographed over a projected five-year periodto determine the location of continents, land masses, islandsand other such geographic points in relation each other.In orbit, it will be as bright as the star Polaris.

The photographs will be taken from positions in darkareas of the world as the satellite's reflection from theSun, below the horizon, is visible for several minutes.

The spacecraft will circle the Earth at a velocity of13,700 miles an hour, and its orbital period will be aboutthree hours. In each 12-hour span, PAGEOS will pass overevery area of th e globe as the Earth revolves on its axis.

The orbital course of PAGEOS will provide many opportu-nities, during its five-year lifetime, for the satellite tobe photographed simultaneously against a star backgroundbv two or more cameras located at stations 2,500 to 2,800miles apart.

The interconnected series of camera positions willcover the entire Earth's surface, enabling scientists todetermine geometrically eacn camera position within asingle reference system.

- morn -


4/24

-3-

The resulting network of spatially-oriented triangleswill be useful in locating any point on Earth, as measuredfrom the center of mass, within 51-96 feet of its true

position.The distance between two surface points 3,000 miles

apart could thus be obtained to an accuracy of 32 feet.PAGEOS will remain in orbit after this series of

Geodetic Measurements have been completed.PAGEOS is fabricated of one-half-mil (one-half thousandth

of an inch)-thick Mylar plastic coated with a micro-thinfilm of vapor-deposited aluminum. The metal coating willreflect sunlight and radio waves and will protect thesatellite from the damaging effect of ultra-violet radiation.

It will be packed inside a canister for launch, thenwill be inflated in orbit. The satellite weighs about 125pounds.

About 10 pounds of benzoic acid and 20 pounds ofanthraquinone, inflating compounds, are dusted on the in-side of the satellite before it is folded and packed in amagnesium canister. The two halves of the canister, whichis 28 inches in outside diameter, are laced together byRayflex cord for the flight into space. The canisterassembly weighs 40 pounds.

- more -


5/24

-4-

At launch, the canister containing the folded sphereis mounted on an aluminum adapter atop the launch vehicle,and enclosed by a heat shield as it travels through th eatmosphere.

Total weight of the spacecraft system, including theinflatable sphere, inflation powders, canister assembly,and adapter fo r mounting the canister to th e launch vehicle,is about 247 pounds.

ZAs the launch vehicle reaches orbital velocity, th ecanister is automatically ejected. The two halves areseparated by an explosive device placed around its lacedmiddle, permitting the folded satellite to inflate tospherical shape.

The inflation process is accomplished as th e benzoicacid and the antnraquinone turn to gas and expand in thesolar heat, aided by th e expansion of the small amount ofresidual air inside th e sphere.

- morn -


6/24

-5-

The inflation gases will leak out during the first twoweeks in orbit, when PAGEOS travels in continuous sunlight,but the satellite is designed to retain its spherical shapefor the duration of the mission.

The PAGEOS project, one phase of the U.S. NationalGeodetic Satellite Program, will mark the first use of anorbiting satellite employing the principles of geometry tomap the Earth's surface completely.

A orime objective of the program is to encourage inter-national participation in ground-based observations, da.taacquisition, and data analysis. A "PAGEOS Experimenter'sInformation Manual" will be published to provide th e ii-formation required for participation in the worldwideobservation project.

rhe U.S. National Geodetic Satellite Program is basedon recommendatiors of the Geodetic Satellite Policy Boardcomposed of representatives of NASA, Department of Defense,and Department of Commevrce. The three agencies are principalparticipants in th e program along with the world scientificcommunity. NASA has overall management responsibility.

- more -


7/24

-6-

The program involves two types of geodesyZ 1.the geometric, which concerns the use of PAGEOS to mapthe Earth's surface within a three-dimensional referencesystem, and 2. the gravimetric, measurement of variationsin the Earth's gravitational field.

Launch of the first geodetic satellite in the program,Explorer XXIX (G:EOS-I), took place Nov. 6, 1965,from the Eastern Test Range at Cape Kennedy. The secondGEOS satellite similar to the first, is scheduled forlaunch in 1967 to make detailed studies of the gravitationalfield of the Earth. It will support geometric observationsfrom camerasspaced about 1,000 - l;200 miles a.art, enablingan evaluation of its five qeodetic instrumentation svs-t ems.

NASA's Office of Space Science and Applications hasprime responsibility for the U.S. Geodetic Satellite Program.The Department of Defense, (U.S. Army Corps of Engineers,Army Map Service) and the Department of Commerce (EnvironmentalScience Services Administration's Coast and Geodetic Survey)are responsible for the tracking network.

more -


8/24

-7-

The PAGEOS project is managed by NASA'o LangleyResearch Center, Hampton, Va., with data Acauisitionunder Goddard Space Flight Center, Greenbelt, Md. LewisResearch Center, Cleveland is in charge of the launch vehicle,with launch management under the Kennedy Space Center's Un-manned Launch Operations (ULO). The 6569th Aero-Space TestWing of the ITS. Air Force will conduct the launch underth e direction of ULO.

The PAGEOS spacecraft was constructed by the G. T.Schjeldah! Co., Northfield, Minn. and the Goodyear AerospaceCorp., Akron, Ohio fabricated the canister assembly and adapter.

Douglas Aircraft Co., Santa Monica, Calif. built thefirst staqe Thor booster. The Agena-D upper stage was builtby the Lockheed Missile and Space Co., Sunnyvale, Calif.

(END OF GENERAL RELEASE; BACKGROUND INFORMATION FOLLOWS)

- more-


9/24

81

PAGEOS BACKGROUNDIn August 1964, NASA approved a Passive Geodetic Earth-

Orbiting Satellite (PAGEOS) project, proposed by the LangleyResearch Center, Hampton, Virginia as part of the U.S.National Geodetic Satellite Program. A satellite similarto Echo I (a 100-foot balloon developed by Langley andlaunched August 12, 1960) was proposed for the PAGEOS geodeticstudy program.This recomunendation was based on the successful ex-perience of the United States in the use of Echo I forvarious scientific purposes.

Echo I proved it was feasible t' . ise a satellite asa passive reflector communications system on a global basis.In its six-year lifetime so far, Echo I has been used toobtain basic information on the characteristics of space.In addition it has been successfully employed for geodetictriangulation measurements by the United States and foreigncountries.Studies conducted in 1964 indicate that Echo I is stillessentially spherical and that its very thin coating of vapor-deposited aluminum has retained a high degree of reflectivity,

but it cannot be used for the PAGEOS project. Scientists saythe orbital inclination is too low to cover the network oftracking stations near polar latitudes and its altitude istoo low to span th e distances across continents and oceans --a capability required for worldwide geodetic applications.PAGEOS Inflation

The sphere will be in continuous sunlight for the first14 days or longer, t.o insure the effective operation of th einflation system.

- more -


10/24

aL

kk

PHIE,, FPOLDEID AND PAC'KAGE',v P~vkGEC3 SATEL1,III'


11/24

-9-

Sunlight plays an important part in the inflation ofthe sphere. The benzoic acid inflation powder turns intogas at a temperature of about 115 degrees F. Unless insunlight, the temperature of the satellite will be wellbelow this value. In continuous sunlight the sphere'stemperature will average about 240 degrees F.

Most of the benzoic acid is expected to leak out ofthe inflated satellite in a few hours, leaving the lessvolatile anthraquinone to sustain a small positive pressurefor about two weeks after this time it too will have escaped.The leakage predictions are based on the results, as estimatedby scientists, of the bombardment of the satellite by meteoroids.

Even though the inflation gases leak out during the firsttwo weeks, the satellite is designed to retain its sphericalshape at least for the duration of the present five-yearscientific mission.

Photogrammetric ObservationsAs PAGEOS orbits 2600 miles above the Earth it will

appear from the ground as a fast-moving star as the sunbeyond the horizon reflects on the sphere's mirror-likesurface against the dark sky.

As the satellite becomes visible to at least two ofthe widely separated camera stations around the world,simultaneous photographs will be made against a star back-ground. The reflected sunlight from the satellite's sur-face produces a point image on the photographs similar tothe star images in the background.

Using geometric techniques, a space-oriented triangularplane is formed by the camera stations and the satellite.On a subsequent pass, similar phiotographs are made and thebase line of the triangie is determined. As other camerastations are brought into use, additional base lines arecomputed. They ther, form a network of triangles coveringthe entire surface of the Earth.

- more -


12/24

-10-

The 69 triangles which will be produced during the five-year mapping experiment will reveal the shape of the Earth.To establish the size of the globe, the lengths of one ofthe base lines of several of the triangles is measured byconventional ground-based techniques. Once several baselengths are established, th e dimensions of all other baselines can be computed, resulting in a more accurate deter-mination of the size and shape of the Earth.

Inflatable Sphere AssemblyThe PAGEOS fabrication process is similar to thatdevised for Echo I.PAGEOS is constructed of 84 gores or panels of Mylarplastic film, .0005 (one-half thousandth) of an inch thick.Prior to fabrication of the sphere, the gores are coated onthe outside with approximately 2,200 angstroms of vapor-

deposited aluminum. (An angstrom, a unit used in measuringthe wave length of light, is the basis for measuring thethickness of th e aluminum film because th e deposit is sothin).In the satellite fabrication process, the gores--eachof which is about 45 inches wide at the "equator" and de-creases to a point at the "poles"--are sealed together onthe inside by inch-wide adhesive tape made of the samepliable plastic material.. The gore ends are joined bypole caps which complete the spherical shape.The completed sphere is packaged into the canisterfollowing scientifically developed folding techniques.The initial folds, called pleat folds, are made in thedirection of the gore seams.BEfore the last gore-to-gore seal, following completionof the pleat folds, the inflation powders (ten pounds of

benzoic acid and 20 pounds of anthraquinone) are dusted intothe sphere along the lengths of the gores. Then the satelliteis folder accordion-fashion across the gore seams, resultingin a generally spherical stack which is carefully hand-packedinto the canister.

The volume of the sphere when folded inside the canisteris five cubic feet as compared to 52.;000 cubic feet and asurface area of 31,000 square feet when inflated in orbit.more -


13/24

AA

(a)ENLARGED SEC;TION A-APLEAT FOLD AlU b) ACCORDION ;\FOLDS

(c) INFLATABLE SPHEriEINSIDE FLIGHT CANISTER

Folding and Packaging of PAGEOS Satellite


14/24

-(

-

-

-

'd

Z~

-n

__-

--

_

_

_

_

_

b


15/24

- 11 -

Spacecraft System

Total weight of the spacecraft system is about 247pounds. This includes 125 pounds for the inflatable sphere;30 pounds of inflation powder contained within the sphereat launch; 40 pounds of the canister, lacing, and the explosivedevice which will separate the two halves in orbit; and 52pounds for the cone-shaped aluminum adapter for mounting thecanister to the launch vehicle.

Canister AssemblyThe canister halves are machined from magnesium forgings,

with an inside dimension of 26 inches in diameter and anoutside dimension of about 28 inches. After th e foldersphere is packaged inside the canister, it is laced togetherwith Rayflex cord. A shaped charge is the explosive -3eviceused to cut the lacing and at the same time provide thepropulsive force to separate the canister halves at thedesired time in flight.

The assembled canister is placed atop the adapter formounting to the liunch vehicle. The PAGEOS adapter providestransition support from the approximate 10-inch canistermounting base at the top of the adapter to the 60-inch-tlruztface of the Agena-D.

Thermal control coatings are carefully applied to theexteri r surface of the canister and adapter in scientificallydesigned patterns. These coatings maintain the temperaturelevels on the interior within prescribed limits while thespacecraft is traveling outside the Earth's dense atmosphereand before the satellite is inflated in orbit.

The `airing which encloses the spacecraft at launchshields it from aerodynamic heating damage during ascentthrough the atmosphere; the thermal control system providesprotection after the fairing is ejected and the spacecraftis exposed to the varying heat and celd--depending on itsposition in flight in relation to the Sun.

- more -


16/24

- 12 -

One of the coatings used is white enamel paint, appliedto control absorptivity on the side facing the Sun. Theother, aluminum-coated adhesive tape, controls the emittanceof heat.Thermal control on the canister prevents excessiveheating, which affects the satellite inflation rate, andexcessive cold areas, which affect the performance of thebatteries in the canister assembly.On the adapter, thermal control protects the electronicequipment located in this area.The internal pressure and external canister temperatureswill be monitored from final assembly until canister in-flightejection.

Department of Commerce - Department of Defense ParticipationUsing PAGEOS as a beacon in th e sky, teams from theCoast and Geodetic Survey and the U.S. Army Map Service willextend precise geodetic surveys across continental and inter-continental distances to measure the size and shape of th eEarth more accurately than ever before.Eight teams of the Coast and Geodetic Survey and fourof the Army Map Service will train highly-sensitive BC-4

cameras, housed in portable observatories, on the satelliteas it passes in crbit 2,600 miles about the Earth.By simultaneous observations of the satellite againsta star background, these teams will determine the anglesbetween adjacent stations, thus forming a world-wide satellitetriangulation network of known geometric angles of some 40stations, each permanently marked. Thus, through cameraobservation alone, the directions between all stations ofth e netowrk will be precisely determined.The present system of satellite triangulation has anaccuracy of one to 400,000. Using PAGEOS, it is hoped toimprove Earth measurements to an accuracy better than oneto 500,000. This means a measurement which is off by onlyone foot in 500,000 feet.

- more -


17/24

-13

The 12 BC-4 satellite triangulation teams will each be Acomposed of four to eight men. They will operate at nightwhen the reflection of the Sun's rays from the passivesatellite can be observed.Each team will probably have to remain at a station

from 6 to 18 months. They will operate on every continent,on virtually uninhabited islands, in the desert, in thetropics, and in the frigid wastes of the Arctic and Antarctic.As each party completes its operation, it will move on to an-other site each time leaving behind a permanent survey mark.Three or four teams will be stationed in Antarctica duringthe final year of the program.The Coast and Geodetic Survey will obtain observationswhich will enable geodesists to reduce and analyze datawhich will result in the establishment of the world-widegeodetic net accurate to within one part in 500000 andtying together major: data. (A datum is a mathematical basewhich enables surveyors to define precise horizontal andvertical positions on Earth).Satellite geodesy will allow world-wide positions tobe refined to a still higher degree as the globe is measuredon a total scale rather than by local increments. Usingsatellites, scientists have already been able to determineth e polar flattening of th e Earth with a precision about10 times that of earlier D'eterminations.

Description of Principal Investigators' Rolesfor PAGEOSThe following Principal Investigators have been assignedfor th e PAGEOS Project:Capt. L_ W. Swanson (Ret.) - USC & GS, ESSA, Dept. ofCommerceDr. Ivan I. Mueller - Geodetic Sciences Dept., OhioState UniversityDr. Charles Lundquist - Assistant Director, SmithsonianAstrophysical Observatory.

- more -


18/24

- 14 -The roles of each of these investigators and their

organizations are summarized as follows:Captain Swanson, Project Manager of USC & GS Geodetic

Satellite Program, directs the agency's participation in theNational Geodetic Satellites Program. USC & GS is responsiblefor establishing geodetic control throughout th e U.S. and itspossessions, and is involved in establishing world-wide geodeticcontrol to aid in defining the shape of geoid and related sci-entific investigations of the Program. USC & GS participationin the PAGEOS Project is sponsored by th e Department of Defense.

Dr. Mueller is Associate Professor of Ohio StateUniversity's Department of Geodetic Science. Under NASAsponsorship, Dr. Muelier is responsible for analysis ofPAGEOS and other satellite data to define a unified worldgeodetic system. His investigations for the PAGEOS Projectwill include an analysis of the relationships of the existingprincipal geodetic datum used by various nations and theunification of these data to a world-wide geodetic systemto provide a common reference network to which all geodeticand topographic data can be related.

Dr. Lundquist directs the Smithsonian AstrophysicalObservatory's participation in the National Geodetic SatelliteProgram. Under NASA sponsorship, Dr. Lundquist will be re-sponsible for obtaining PAGEOS observations with the BakerNunn cameras and for analyzing other observational data obtainedby th e USC & GS and international observers for two purposes:1. To determine the position for the 12 Baker-Nunn stationsin a common coordinate system. 2. To determine relationshipsof the geodetic data involved, from knowledge acquired ofstation positions, various geodetic data, and direct positionsderived from satellite analyses.

All observations of PAGEOS will be reduced by the ob-serving agencies and transmitted to the Geodetic SatellitesData Service at NASA's Goddard Space Flight Center, Greenbelt,Md. The Data Service will store all observational data anddisseminate them to th e Principal Investigators and otherqualified scientists on request. Data from PAGEOS and fromother geodetic active satellites (GEOS-I etc.), also storedand disseminated by GSDS, will be used by the Principal In-vestigators to fulfill objectives of the program.

-more-


19/24

- 15 -Launch Vehicle

The PAGEOS launch vehicle is a thrust augmented Thor(TAT) booster with three TX33-52 solid rocket motors, anAgena-D second stage and the PAGEOS spacecraft.

The TAT is primarily aluminum and needs no tank pressuri-zation to be self-supporting. Its engines include a Rocket-dyne main turbopump-fed liquid propellant engine, two Rocket-dyne liquid propellant 1000-pound-thrust vernier engines andthree jettisonable Thiokol solid rocket motors. Liquid pro-pellants are RJ-1 hydrocarbon fuel (35,213 pounds) and liquidoxygen (67,600 pounds).

The main engine can be gimbaled in flight for controlin pitch and yaw while the vernier gimballing provides rolland attitude control. The Thiokol solid propellant motorshave 53,425 pounds of thrust with a total burn time of alittle more than 40 seconds during the initial boost stageof the PAGEOS flight.

The Agena upper stage has telemetry, guidance andelectrical power components mounted in module form tosimplify checkout and on-the-pad servicing.

The Agena's engine is a dual-start Bell Aerosystemsmodel 8096 designed for 240 seconds of operation at highaltitudes and 16,000 pounds of thrust. The propellants arestorable unsymmetrical dimethylhydrazine (UDMH) fuel andinhibited red fuming nitric acid (IRFNA) oxidizer. Pro-pellant storage tanks are pressurized with helium to ensurepropF_ pump operation.

At the end of the propellant tanks are sumps to containthe propellant during weightless coasting periods. Thesumps contair a fine mesh screen permitting propellant flowsinto the sump during engine burn and inhibiting a returnflow during the weightless coasting phases of Agena flight.These sumps eliminate the need for ullage rockets.

- more -


20/24

-16-Flight Sequence

The TAT rises vertically from Space Launch Complex75-1i1 at the Western Test Range for about 2 seconds beforebeginning a programmed roll to the flight azimuth and pitchingover to the PAGEOS trajectory. The three strap-on motorsburn about 40 seconds with full thrust and are jettisoned65 seconds after liftoff.

TAT main engine cutoff (MECO) occurs when the vehiclereaches its proper. altitude and velocity (some 150 secondsafter launch). Thor vernier engine cutoff (VECO), some nineseconds after MECO, signal's the start of the separationsequence.

About 14 seconds after separation, Agena pitches downto prepare for its first burn, beginning about three minutesafter liftoff. The engine hydraulic system controls thevehicle in pitch and yaw while roll remains under pneumaticcontrol during the burn. The clamshell-style protectiveshroud is ejected during first burn at about T plus 194seconds.

Agena's engine burns until it has increased the vehicle'svelocity some 11,000 mph. The Agena velocity meter then shutsthe engine off about 417 seconds into the PAGEOS flight.

Agena, carrying its now unshrouded PAGEOS payload,coasts from first-burn cutoff altitude around 110 miles toits orbital altitude of 2600 miles. About 73 minutes afterliftoff, preparations for second burn begin. This secondburn is short, about 11 seconds, ending when the velocityhas increased some 1740 mph.

Agena/PAGEOS at this point is in the 2600-mile-highcircular orbit required for the spacecraft. One hour and15 minutes after liftoff, a spring-ejection mechanism placesthe payload canister in orbit ahead of Agena. Two secordslater, Agena begins to tumble to preclude the possibilityof the empty Agena hitting the canister and spacecraft.

An explosive device around the middle of the canisterseparates the container halves, leaving the folded sphereto inflate in orbit. This occurs one hour, 15 minutes and45 seconds after liftoff. PAGEOS begins to inflate some 85seconds after the canister is ejected. At this point, PAGEOSshould be 650 feet from Agena.- more -


21/24

4

$

'4

I

kWk


22/24

- 17 -

The Agena-D, which will follow the satellite closelyduring the first few orbits, is equipped with a Minitrackbeacon. Its signals (136.050 mc) will assist in determiningthe sphere's initial orbit. This calculation is based onknown attitude and separation velocities between vehicle andspacecraft canister.Launch Vehicle Statistics

Height TAT/Agena/PAGEOS 85 feetWeight TAT/Agena/PAGEOS 15,253 pounds

TAT Booster Agena up~er stageHeight 56 feet 20 feetDiameter 8 feet 5-feetWeight 107,000 pounds 15,775 poundsPropulsion Rocketdyne main one Bell 8096 mainengine, two Rocket- enginedyne verniers, threeThiokol strap-on solidrocket motorsPropellants RJ-1 hydrocarbon fuel UDMH fuel and IRFNAand LOXThrust 332,275 pounds at 16,000 pounds at altitudeliftoff, 160,275 poundsof which are the threestrap-on solid motorsPrimeContractor Douglas Aircraft Co., Lockheed Missiles &Santa Monica, Calif. Space Co., Sunnyvale, Calj

- more -


23/24

Flight Sequence- 18 -

Liftoff 0Solid booster cutoff 43 Sec.Eject solid motors 65Thor main engine cutoff (MECO) 150Thor vernier engine cutoff (VECO) 158Thor/Agena separation 162Start Agena first burn 185 "Jettison shroud 194End Agena first burn 417Start Agena second burn 4355 "End Agena second burn 4366 "Separate PAGEOS spacecraft 4462

- more -


24/24

- 19 -

THE PAGEOS PROGRAM TEAMNASA Headquarters -Office of Space Science and

ApplicationsJerome D. Rosenberg PAGEOS Program ManagerJ. B. Mahon Agena Program ManagerLancrlev Research CenterDewey L. Clemmons, Jr. PAGEOS Project ManagerBert C. Deis Assistant Project ManagerLewis Research CenterH. Warren Plohr Agena Project ManagerD. Lewis PAGEOS Vehicle EngineerGoddard Space Flight Center

J. B. Zegalia Tracking and Data SystemManager

Kennedy Space CpnterJ. B. Schwartz Acting Manager, Unmanned Launch

Operatiors, Western Test Range

-O -

Documents

Pageos Press Kit