s-3 energetic particles satellite press kit

8/8/2019 S-3 Energetic Particles Satellite Press Kit

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RELEASE NO. 61-172

NEWS R E L E A SNATIONAL AERONAUTICS AND SPACE ADMINISTRAT1 5 2 0 H S T R E E T , N O R T H W E S T . W A S H IN G T O N 2 5 . DT E L EP H O N E S : D U D LE Y 2 - 6 3 2 5 . E X E C U T I V E 3 - 3

SundayRELEASE: August 13, 1961

E'ION. c .2 6 0

S-3 ENERGETIC PARTICLES SATELLITETO BE LAUNCHED BY NASAThe National Aeronautics and Space Administration soonwill launch the first of a series of spptcecraft that will studythe behavior of energetic particles - electrons and protons, theminute building blocks of matter - that are present in space andaffect geophysical phenomena on earth.The complex 83-pound octagon-shaped spacecraft instrumentedwith scientific experiments from universities and governmentlaboratories will be placed in orbit by a three-stage Deltavehicle from Cape Canaveral, Florida. The satellite with itshighly eccentric orbit extendin from a low altitude (perigee)of abou% 170 miles to a height 7apogee) of about 50,000 milesoffers a unique opportunity to study the physics of fields andenergetic particles in space.The satellite is the first of four designed specificallyto make repeated observations of the solar wind, the interplane-tary magnetic fields, the distant regisns of the earth's magnetic

field, and the particle population of interplanetary space andthe trapped radiation regions (the V a n Allen belts). Thesebelts, which will be traversed twice in the anticipated 31-hourorbital period of the satellite, surround the earth at latitudesof less than 70 degrees and between 600 and 30,000 miles.The Goddard Space Flfght Center, Greenbelt, Maryland, hasthe m J o r responsibility for the Energetic Particles Sstellite,its integration with the Delta launch vehicle, and trackingand data reduction. Essentially, the project consists of sixexperiments:Cosmicand a solarCenter.Protonof NASA,

ray experiment, an ion electron detector experimentcell experiment, all by the Goddard Space Flightanalyzer experiment by the Ames Research Center


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Magnetfc field experiment by the UniverPsity of NewHampshireTrapped particle radiation by the State University ofIowa.In addition, there is a Goddard photocell optical sensing

k e xperiments will measure the entire particle Spectrasystem that will furnish information on the satellite'sorientation 9n space.from energies of a few electron volts to 10 billion dr morethan l0'degades of energy. A magnetometer on a boom some 32inches from the satellite body will determine the particles'interactions with magnetic f i e l d s .

At its highest altitude, the satellite essentlally wlllbe in interplanetary space beyond the influence of the earth'smagnetic field.are few (less than 100 t o the cubic inch) and very slow-moving.The number of cosmfc rays - also possessing high energies - 'are even smaller, less than one to the'cubicyard, hut theinterplanetary magnetic field still slightly influences aparticlefs otion with a force about one ten-thousandth thestrength of the earthPs magnetic field.

Here, electron'and proton particles normally

As the satellite moves away from maximum height, it willpass through thb doughnut-shaped Van Allen radiation belts -essentially storage bins for energetic particles which aretrapped by the earthOs magnetic field. Geophysical phenomenaare created when these particles sift down into the atmosphere-communications blackouts and disturbances, magnetic storms,and auroral - northern and southern lights - displays.nation angle of 33 degrees from the equator. Due t o the highlyeccentric orbit and small power of its transmitter, it willbe one t o two weeks before an accurate orbit can be determined.

Since-the rbital period is 31 hours, almost a day maypass before an orbit can be confirmed. An attempt will be madet o use the Trainidad radar to cover the point of injection, butsince the target will be low on the horizon (four degreeselevation) no precise injection velocity information will beavailable. However, this radar should give an indication ofsuccessfuP orbit.

The Delta vehicle will launch the spacecraft at an incli-

An orbital period of approximately 31 hours will make thespacecraft visible foro approximately 23 hours a day at stationson the apogee side of' the earth. Three Minitrack stations -at Woomera, Australia; Santiago, Chile;and Johannesburg, SouthAfrica - will record the telemetry signals 90 percent of thetime. Telemetry will be recorded continuously for one month-2-


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and periodicelly thereafter, On the fflast orbftal pass perigeeshould be 14 N latitude, 490W longitude (Atlantic Ocean).apogee, the latitude should be 120s latitude 99% (PacificOcean).At

PROJECT PARTICIPANTSThe over-all responsibility for the Energetic ParticlesSatellite project rests with the Gcrddard Space Flight Centerof the National Aeronautics and Space Admfnistration withexperiments being contributed by Goddard, the Ames ResearchCenter of NASA, the State University of" Iowa, and $he Universityof New Hampshire. Approximately 50 industrial firms havecontributed to the program.Officials concerned with the mergetic Particles Satelliteproject include:NASA Headquarters: Morton J, S t o l l e r , Assfstant Director,Satellite & Sounding Rocket Programs;D r . John E. Naugle, Energetic ParticlesProgram, S -3 Program Chief"; and I. L.Cherrick, Flight Systems, S -3 ProjectOffieer.Goddard Space Plight Center: Paul Butler, Payload Manager;Dr, Frank B. McDonald, ScientificAdvisor; Gerald W o Longaneoker, Payload

Cosrdinatctr; Frank Martin, PayloadStructures; Willfam Schfndler, LaunchVehfcle; Fred C, Yagerhofer, Power)Systems; James E, Scobey, Telemetry;Jeremiah J, Nadden, Tracking Scientist;Robert W, Rcchslle, Flight Data System;Vietor Sfmas, Tracking; Gy m s Creveling,Data Processing and. Analysis.

EXPERIMENTER$ AND INSTITUTIONS FOR 9333 SCImTIFEC EXPERIMENTSAmes Research Center: Dr. Michael -der, Proton AnalyzerExperiment:.University of New Hampshire: Dla. Laurence Cahill, Magne-tometer Eseperiment

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State University of Iowa: Dr. James A . Van Allen andDr. Brian J. O'Brien, Trapped RadiationExperiment.Goddard Space Flight Center: Dr. Frank B. McDonald, CosmicRay Experiments; Mr. Leo Davis, IonElectron Detector.

EXPEVIMENTERS AND INSTITUTIONS FOR THE ENGINEERING EXPERIMENTSGoddard Space Flight Center: Mr. G. W. Longanecker, S o l a rCelliExperiment; Mr. James S. Albusand Mr. David H. Shaefer, OpticalAspect .

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N A S A D S EhERGETIC PARTICLES AND FIELDS PRWRAMThe S-3 s e r i e s of s a t e l l i t e s t o measure energet ic par t ic lesand t h e i r r e l a t i o n sh i p s w i t h f i e l d s i n space i s a no th er s t e p i nt h e o v e r a l l NASA program o f l t h e peacef ul-expl orat ion of space

f o r the b e n e f i t of a11 mankind, The sc i e n t i f i c e xp er im en ts arefrom un iv er si ti ds and government l ab or at or ie s.The energe t ic pa r t ic le s port ion of the program i s concernedw i t h the study of t h e p a r t i c l e s w i t h energy greater than a fewe lec t ron -vo l t s t h a t are found in the t rapped and aurora l rad ia t ion ,and the i n t e r p l a n e t a r y plasmas, 1 -Eventual ly , the t rapped and aurora l rad ia t ion associa tedw i t h t h e o t h e r p l a n e t s and the moon will be s tud ied , The i n t e r -a c t i o n between the cha rged pa r t i c l e s and the magnetic f i e l d s i ssuch t ha t they must be st ud ie d simul taneou sly on t h e same veh ic lesi n or de r t o under sta nd th e phenomena; hence th e S-3 ser ies .Certain of the phenomena are re l a t ed to the 11-year s o l a rcycle, and i t i s necessary t o monitor these phenomena c a r e f u l l yo v e r an 11-year period, A t the present t i m e we are i n at r ans i t ion pe r icd f rom h igh s o l a r a c t i v i t y towards the nextm i n i m u m which w i l l occur i n 1965. Associated w i t h thesephenomena are ce r t a i n fundamenta l quest ions such as t h e o r i g i nof cosmic ra ys and t h e na tu re of the in te rp lane t a ry f i e l d . T h elong-range obgectivea of the program are t o f i n d the answerst'd these quegt ions and t o any new quest i ons which a r i s e as the

NASA exploratory program proceeds,Most of t h e 23-3 experiments w i l l examine the chargedp a r t i c l e s i n space outs id e the e a r t h f s atmosphere. These areprotons, t h e n u c l e i o f hydrogen atoms which continually f l y outfrom the sun, and the very f a s t cosmic rays which stream ac rossou r s o l a r system from unknown source's, Ssnce such p a r t i c l e s aree l e c t r i c a l l y c harged, t h e i r f l i g h t i s s t r o n g l y a f f e c t e d b y themagnetic f i e l d s i n space, A t the same t i m e t h e y c r e a t e addi -t i o n a l ma gn eti c f i e l p s as th ey move th roug h spa ce ,accurate measurement d f the s t r eng th and d i rec t ion of the i n t e r -pla net ary magnetic f i e i d is a v i t a l o bj ec ti ve of the s c i e n t i f i cprogram of the S-3 s a t e l l i t e s ,

Thus t h e

Most of t h e p a r t i c l e s which S-3 w i l l observe come origi-na l l y from the sun , The magnetic f i e l d which S-3 w i l l measureo r i g i n a t e s p r i m a r i l y in the sun from which i t i a to some un-known extent t ranspor ted and warped by the streams o f p a r t i c l e s .But ne i the r t he streams of p a r t i c l e s n o r the i n t e r p l a n e t a r ymagnetic f i e l d can be d i rec t ly obse rved on the sur fac e of theearth, o r even f r 8 m a poin t seweral hundred miles above the

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,earths8 su rfa ce . Not only does the atmosphere of the ear ths h i e l d u s from almost a l l pf the re la t i ve ly slow-moving pa r t ic le st h a t come from the sun, but also the magnetic f i e l d of the earthd e f l e c t s the motion of the par t icles and overr ides the com-p a r a t i v e l y w e a k magnetic f i e l d of apace.th e sun have very important consequences on t h e su r face of theearth. For example, magnetic storms on the ear th which inter-f e r e with rgdio transmission appear to be d i r e c t l y ca used bydisturbances on th e sun, and even the aurora boreal is- thenorthern lights--seem t o r e s u l t f rom s o l a r a c t i v i t y . O f course,the e a r t h ' s weather is con t ro l l ed by t h e sung and changes i nweather may result from v a r i a t i o n s i n s o l a r a c t i v i t y ,happenings on the sun. However, our present understanding ofsolar behavior i s l imi ted i n that we c an no t r e a l l y determinethe mechanisms which re la te some s o l a r phenomena t o thephenomena we observe here on the earth, The sc i e n t i s t s makingmeasurements on t h e S-3 spacecraf t hope these observat ions willadd to our knowledge of the sun and i t s r e l a t i o n to the earth.

I n s p i t e of t h i s s hi el di ng , a c t i v i t i e s on the su r face of

Many happenings on ear th may be connec ted d i r ec t ly to

Cosmic RadiationGalac t ic cosmic rad ia t i on con si s t s of a very low f luxof p rotons , a lpha pa r t i c l e s and nuc le i of he av ie r atoms. These

%@Eve The f l u x v a r i e s by a f a c t o r of two over th e l l - y e a rso la r cyc le and occas iona l ly decreases s h a rp l y f o r a few daysa f t e r a s o l a r f lare-- the so-called Forbush decreases, Theo r i g i n of t h e par t i c l es , the mechanism by which they are,ac-c e l e r a t e d t o high energies, the nature of the mechanismand the Forbush modulation of th e f l u x and energy spectrum--these are some of t h e questions which have shaped the NASA ex-perimental program.

i c l e s range i n energy from a f e w m i l l i o n e l e ct r o n v o l t s t o

( o r mechaniams) which produce the l l - y e a r solar cyc le

Sol ar cosmic ra d ia t i on was i d e n t i f i e d i n 1942 when measure-mehts showed t ha t a f e w hours a f t e r a large s o l a r f l a r e thepol ar reg ions of the ear th were bombarded by protons, withenergies varying from 40 m i l l i o n e l e c t r o n v o l t s t o a bo ut 1b i l l i o n e l e c tr o n v o l t s, These bombardments l a s t from a f e w hoursto severa? days, and t h e i r study has a l r eady l e d t o t h e d e f i -n i t i o n o f th e fol lowing areas requir ing experimental andt h e o r e t i c a l i n v e s t i g a t i o n :

--Composition, f l u x and energy sp ec tr a of the p a r t i c l e sand the v a r i a t i o n s o f these q u a n t i t i e s w i t h time andposi t ion dur ing an event .

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--The nature of the accelerating mechanism of the sunand the relation between it and other solar phenomena.--The tradectories of the particles and their distributionin space during an event,--Variation of the frequency and intensity of these eventswith time oveF an entire $1-year solar cycle.--Radiation levels in space.

Auroral and Van Allen Belts RadiationTrapped and auroral radiation are related to the greatradiation belts, The Van Allen radiation belts consist of twomajor regions. The inner region 18 stable with time andcharacterized by a high density of protons of energies in therange from a few million electron volts to 700 million electronvolts, The character of the outer region varies with time,

and the available evidence indicates that the radiation con-sists of particles with energies less than one million volts.(Recent evidence has shown that observed fluctuations inintensity in the outer region cannot be accounted for on thebasis of solar particles injected into the earth's magneticfield,) Presumably, there must be a mechanism In the vicinityof the earth which accelerates the particles found in the belts.Measurements taken during the International GeophysicalYear have shown that both Pow energy protons and electrons areassociated with ~ I A P O F ~ , ith the major part of the incidentenergy carried by the electrons,Some of the major questions in this area are:--Origin of the radiation in the various regions ofthe belt--Life time and tragectories of the particles.--Nature of the l o c a l accelerating mechanism.--Relation between the trapped and auroral radiation.--Effects of the radiation on the atmosphere andionosphere,--Existence and nature of the belts on the otherplanets and the moon.

Interplanetary PlasmaThere are several fundamental questions on the inter-planetary plasma:

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--Composition of the particles.--Number density, directional flux, and energy spectrumof the particles.--Relation of these properties to the magnetic field atthe same point at the same time.--Time variations from short periods (hydromagneticwaves) to periods of 11 years (solar cycle).

Magnetic FieldsThe magnetic field portion of the NASA program seeks tomeasure the magnetic fields of the Sunj planets, and naturalsatellites of the solar system, and of interplanetary space.Experiments, such as the S-3, are! o be carried out in con-junction with the scientific investigation of the physicalprocesses causing the fields and their time changes. Simul-taneous measurements of particle fluxes and plasma densitiesare required to understand the interaction between thesephenomena and the magnetic field.The major problems and objectives of the program are:--To survey the geomagnetic field in as great detailas possible over the whole earth.--To investigate the sources, presumably ionospheric,of electric current systems that give rise to suchground-observed phenomena as the diurnal magneticvariations (solar and lunisolar) including the morepronounced variations caused by the equatorialelectrojet; and also the magnetic storm changes,particularly the polar disturbances.--To study the character of the outer geomagneticfield including the rapid fluctuations that may berelated to hydromagnetic waves in the exosphericplasma. The evidence from the Russian satellitesand also from Explorer VI, and Pioneers I and V,has suggested the existence of a ring current. How-ever, controversies as to the interpretation of thesedata have created the need for more investlgations,which the eccentric orbit of the S-3 series ofsatellites will make possible.--To study the interplanetary field and its fluctu-ations which, presumable are due to "frozen" fields

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fluxgate, the proton precession and the rubidium vapor magne-tometer, -The search coil consists of a coil of wire mounted in aspinning vehicle. The voltage output from the coil is ameasure.of the scalar field at right angles to the spin axis.

Such a magnetometer can also be used to measure fluctuatingfields in a non-rotating vehicle.The fluxgate magnetometer is a three-core device: Eachof the three orthogonal sensors will produce an output voltageproportional to the magnitude of the component of the com-bined magnetic field along the axis of that 8ensor. The out-put voltage of the three sensors w i l l each occupy a separatetelemetry channel and will be combined after reception toform the total magnetic field vector,The output of a proton precession magnetometer is afrequency proportional to proton magnetic moment and the

strength of the local field. Since the proton magnetic momentis known very accurately, the field can be determined to theaccuracy with which this frequency is measured.The output of the rubidium-vapor magnetometer is also afrequency proportional to the local magnetic field. The advantageof thia instrument over the proton magnetometer is that it canbe used to measure very rapid fluctuations and has a greaterdynamic range.

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FACT SHEETSS-3 SPACECRAFT AND SUBSYSTEMS

GENERALThe 83-pound energetic particles satellite represents

a milestone in engineering design with its capability ofaccommodating 10 particle detecting systems, and associatedelectronics, all in a usable volume area of 1.578 cubic feet.An octagon-walled platform, fabricated from nylon honey-comb and fibreglass, with an aluminum cover .020" thick, housesmost of the electronics and instruments. Height of the octagonis 5* inches.Volume within the octagon is 1.578 cubic feet. A transmitteris located in the base of the payload, allowing heat to dissipatethrough the structure and aluminum cover.

I t is 26 5/32" across the flats of the octagon:

A magnetometer package, containing three orthogonallymounted saturable core magnetometers and calibration coils, islocated forward of the platform on a boom which extends 32".This reduces field effects from the electronics and instruments.

Four spring-loaded solar-celled paddles with an area of3.84 sq. feet extend from the main structure, giving it adiameter of about 60" when in orbit. The paddles are 13.68"long and have a width of 20.18~'. The 5600 solar cells weigh11 pounds.cell projection area at any payload-solar attitude.are folded along the last-stage rocket t o permft their instal-lation within the nose fairing.Ade-rspin device is provided to reduce the roll rate to approx-imately 31 rpm after last stage burnout. Erection of thepaddles further reduces the r o l l t o approximately 18 r p m .

The paddles are oriented to allow a uniform solarThe paddlesThey are erected during flight.

Weight represented by electronics is 24.5 lb.Weight represented by scientific experiments is 17.85 lb.Weight represented by solar cells is 11 lb.Weight represented by structure is 23 lb.Batteryweight of 13 silver-cadmium storage batteries,providing 15 watts of power,isare available from the solar paddle wheels.

of telemetry per second.

11 pounds. Five watts of powerA 2-watt, 136-megacycle transmftter, provides 50 samples

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Optical Aspect Sensorthe orientation in space of the satellite as a function of time.Six photo-diodes give 180 degrees digital indication of thesunDs levation with respect to the spin axis of the satellite -the 180 degrees from pole-to-pole being divided into 63 parts.The time within the telemetry frame of the sunfs ppearanceis coded in binary form. Read-out of all the time and positioninformation is by two telemetry channels. The system consistsof two basic parts. The fibst is a digital solar aspect sensor,consisting of a light mask aqd a number of photo-diodes placedbehind the light mask so that each photo-diode sees only theportion of the light mask directly behfnd it. The second partis a digital computer having memory and logic f o r determiningthe time at which a photo-diode sees the sun and for rememberingwhich photo-diode had the input.rectangular 2 x 2.5 x 2 lnclnea and weighs 248 grams.electronics is a printed card, 5 x 7 inches.

The spacecraft carries an Optical Aspect Sensor to determine

The sensor package is basicallyThe

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LAUNCE VEHICLE FO R S-3Launch ve hicl e f o r the S-3 s a t e l l i t e i s t h e th ree-s tageDelta ro cke t, The vehi cle i s programmed t o p la ce t h e 83-pounds a t e l l i t e i n t o a h i g h l y e l l i p t i c a l o r b i t , w i t h an apogee ofapproximately 54,000 miles, per igee of about 170 miles and ano r b i t a l i n c l i na t i o n of 33 degrees t o the equator . The or b i t a lper iod i s expected to b e about 31 hours,Vehicle prime c o n t r a c t o r f o r t h e National Aeronauticsand Space Administration i s t h e Douglas Aircraft Company. A sprime contrac tor , Muglas i s respons ible f o r the design, manu-fa ct ure , assembly, t e s t and launch of t h e Delta.Vincent I,. Johnson i s ' v e h i c l e program manager f o r Deltaa t NASA He adq uar te rs .Today's launch w2s t he s i x t h i n t he Delta vehicle program.O f the p rev ious f i ve f i r i ng s , fou r were success fu l and r es u l t e d

i n t h e o r b i t i n g o f t h e Echd I , Tiros 11, Explorer X, andTi ros I11 s a t e l l i t e s . The f i r s t Delta launch was an unsuccessfulattempt t o o r b i t a n Echo s pher e on May 13, 1960.The successful Echo was launched Aug. 12, 1960; Tiros I1on Nov. 23, 1960; Explorer X on March 25, 1961; and Tiros I11on July 12, 1961.

FLIGHT SEQUENCE

A l i f t o f f , t h e 92-foot-high Delta weighs s l i g h t l y l essthan 112,dOO pounds. The f i r s t - s t age Thor rocke t bu rns fo r160 seconds, and i t s l50,GQO - pound-thrust engine prop els t h eveh ic le t o a n a l t i t u d e of 46 miles and 189 miles down range.Second-stage se pa rat io n and ig n i ti o n follo w almost imme-d ia te ly , and 4'2 seconds la ter t h e f a i r i n g s are j e t t i s i o n e d bymeans of explosive bclts.Second-stage engine cutoff occurs about 270 seconds a f t e rlaunch. The second and t h i r d stages then coas t fo r s l i g h t l ymore th an s i x minutes, t rave2in g 1300 miles down range andreach ing an a l t i tu de o f 185 m i l e s during t h i s per iod .I n r a p i d succession, rockets sp in up the t h i r d s tage ,exp los ive bo l t s and r e t ro rocke t s are f i r e d t o separate t h esecond and t h i r d s tages , and th e th i rd-s t age engine is i g n i t e d .It burns for 42 seconds, placing t h e payload and third-stage

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c as in g i n t o o r b i t . A t cutoff , t h e engine and payload are almost2200 m i l e s from Cape Canaveral, and tr av el in g a t a v e l o c i t y o fmore than 24,000 MPH.A 24-minute coas t peri od follows, perm itt i ng exhaust gasesfrom t h e burned-out th i rd - s tage engine t o d i s s i p a t e .t h i s period, YO-YO weights on t h e payload despin the casingand s a t e l l i t e , An e xp lo si ve -a ct ua te d c u t t e r t he n s e ve r s anylon lanyard, re leasing t h e four payload paddles, and explosiveb o l t s a n d a spring mechanism separate t h e S-3 from t h e t h i r ds tage.

During

During t h e f i r s t minute and a h a l f of powered f l i g h t ,t h e T h o r a u t o p i l o t s t a b i l i z e s t h e veh ic le . Radio command gu idanceprovided by t h e Bell Telephone Laboratories then takes over andcon t ro l s t h e rocke t u n t i l second-stage engine c u t o f f .During t h e f i r s t coast period, a Douglas-designed f l i g h tcon t ro l system d i r e c t s the second and t h i r d stages, de tec t ingd e v i at i o n s i n p i t c h , yaw and r o l l and ac t iv i a t ing t he necessarys t a b i l i z i n g helium j e t s .S t a b i l i z a t i o n of t h e t h i r d stage i s achieved b y spinningi t and t h e payload up t o 143 revolu t ions per minute.

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TRACKING AND DATA-ACQUISITLON OF THE- $ ; H m C P A m m ?Owing t o the h igh ly ecc en t r i c o rbTt and th e an t i c i pa tedquality and amount 'of data, i t i s expected tha t 1-2 weeks w i l lbe required t o determine an accu ra t e o rb i t . An attempt w i l l

be made t o use the Trinidad radar t o cover th e poi nt of inject icn.However, owing t o the low horiz on as pe ct of t h e ta r g e t a t t h i st i m e (approximately 4 degrees eFevation) it i s not expectedt o acqu i re any p rec i se inyec t ion v e lo c i t y in fo rmat ion ,o therthan an l ind ica t ion of success fu l o r b i t .information w i l l be developed from succeeding passes of.satellite.and antennas f o r t racking and acquiring data from t h e s a t e l l i t e .Telemetry Operations

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Improved positionalThe Minitrack network has i n s t a l l e d r e c e i v e r s

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Because of the high ly eccen t r fc o rb i t , the spacecraf t w i l lbe v i s ib le for approximately 23 hours a t stat ions on the apogees ide of the earth.and spaced i n long itude w i l l record t he t e lemet ry s ign a l for90 percent of t h e t i m e .ana Johannesburg.Present p lans are t o record t e lemet ry con t inuous ly f o r 1monthand per iod ica l ly thereaf ter as required .

Three receiving s t a t io ns proper ly equippedThese s ta t ions are a t Woomera, Santiago,A l l s t a t i o n s are tuned t o 136.020 Mc.

Tracking Operationsmodified t o improve s ignal -nolse r a t i o s on t h e i r f i n e - t r a c kdntenna groups.Johannesburg, Santiago, Antofagasta, and L i m a .

Exis t ing Min it rack s t a t i on s on the apogee side have beenThe apogee t rack ing s t a t io ns a re a t Woomera,

The r a p i d passes of th e s a t e l l i t e through the perigeew i l l be sampled as t h e s a t e l l i t e @ po ss es e x i s t i n g M in it ra cks t a t i o n s s u ch as Blossom Point, Maryland; F t . Myers, Flor ida ;and Goldstone, Calfformla.The or bi ta l per iod i s approximately 31 hours. On t h ef i r s t o r b i t a l pass t h e l a t i t u d e i s pred ic ted t o be 14ON a tpegigee, t h e longitudeo4g0W.12 S, th e longi tude 99 W. A t apogee, the l a t i t u d e w i l l beA t launch, ea r l y t rack ing data w i l l be col l ect ed by theFt. Myers, F l o r i d a Minitpack station and the Goddard Space

Flight Center Cape Canaveral T/M st a t i on . Rzuaa and ot he rA t l an t i c Missile Range radar i n f o m a t i o n w i l l be a v a i l a b l et o GSFC f o r incor por ati on i n t o a, computer program.informat5on on range and velocitydof the booster s tages providedby t h e AMR radar t r a c k w i l l provide inputs f o r computing theThe vec to r

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i n i t i a l i n j e c t i o n p o i nt v e l o c i t i e s of t h e s p a c e c r a f t t o anominal o r b i t , a f t e r which data from the Mini t rack and o t h e rt r a c k i n g s t a t i o n s w i l l be added i n t o the computer problem t oc o r r e c t the o r b i t c a l c ul a t i on s . As th e Mini t rack s t a t i onsr ece ive a d d i t i o n a l data, t h e accuracy of t h e ca lcu la t ed param-e te r s of the o r b i t w i l l be continuously improved.The Ascension Island T/M r e c e i v e r w i l l provide an oppor-t u n i t y t o a cq ui re a f i r s t look a t the s p ac e cr a ft i n o r b i t .AFMTC, AM Range w i l l add a 136.020 Mc feed t o the TU-18antenna there .

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EXPERIMENTS I N S-3 SPACECRAFTP r i o r t o P ro je c t S-3, severa l impor t t experiments were

--Explorer V I , launched August 7, 1959, de tec ted a r i n gcompleted i n the Energet ic Par t ic les and- e l ds Program.

of e l e c t r i c a l c u r r e nt c i r c l i n g t h e earth, and obtaineda complete map of the Van Allen Radiat ion Be l t .instru mentat ion t o make ac cura te magnetic f i e l d nieasure-ments .--Vanguard 111, launched Sepbmber 18, 1959, c a r r i e d

--Explorer VII, launched October 13, 1959, c o l l e c t e d dataon energe t i c p a r t i c l e s i n the Van Allen Belt.--Pioneer V, launohed March 11, 1960, supplied ad di t i on aldata o w m e r g e t i c p a r t i c l e s and t h e i r d i s t r i b u t i o n and

data on th e in te rp la ne ta ry maknetic f i e l d .--Explorer X measured magnetic f i e l d s i n n e ar e a r t h spa ce .The primary object ive of S-3 s e r i e s o f s a t e l l i t e s w i l lbe t o desc r ibe completely the t rapped corpuscular rad ia t ion ,so la r pa r t i c l e s , cosmic r ad ia t ion , the s o l a r winds, and t oco r re la te the p a r t i c l e phenomena w i t h magnetic f i e l d obser-vat ions . A d e sc r i p t i o n of the experiments follows:

Proton Analyzer Experiment (Ames Research Gerit.er of NASA,D r . M. Bader)The purpose of t h i s experiment i s t o measure low energyproton f lux and spectrum i n space from one qu ar te r t o 10ear th r a d i i (1,000 t o 40,000 miles) .bel ieved t o account fo r 85 percent of th e energ ized pa r t ic le si n spa ce . Data obtained w i l l increase our knowledge o f protonconcentra t ions i n s o l ar winds caused by s o l a r f l a res .data w i l l a l s o be u s ef u l f o r c o r r el a t i n g p a r t i c l e a c t i v i t yi n space i n th e Van Allen Radiat ion B e l t s wi th s o l a r a c t i v i t y .Many scient ists consider t h e i n t e r p l a n e t a r y plasma assimply the contin uatlon of t he sun's atmosphere i n t o t hespace between the planets. This atmosphere, o r corona,con s i s t s mos tly of protons and el ec tr on s. The cloud i ss o d i f f u s e t ha t ordinary pressure and tern erature measurements

t h a t t h e i n t e r p l a n e t a r y plasma i s a r e l a t i v e l y s t a t i o na r ycloud of gas surrounding the sun.s c i e n t i s t s b e l i e v e tha t a s o l ar wind co nst an t ly streamsaway f r o m the sun. T h i s solar wind consists of ion ized

These pa r t i c l e s areThese

o t be made o 100 p a r t i c l e s p e r CM3 as compared w i t h;gTg p a r t i c l e s a t sea le ve l) . Some th eo ri es suggestOn the other hand, other

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atoms of gas (pr imari ly hydrogen) which move with velocitiesof several hundred to a thousand miles a second. Recentmeasurements from Explorer X have tended to confirm theexistence of the solar wind.All descriptions of the interplanetary plasma picrtureit as being disturbed by outbursts of solar activity -- solar

flares or magnetic storms on the surface of the sun. At suchtimes, the density, the speed of flow, and the temperatureof the interplanetary plasma probably all change.The solar wind is presumed responsible in large part formany phenomena observed on earth, such as geomagnetic dis-turbances, auroras, and interference with radio communications.The flux of plasma particles number of particles incidenton a given area per unit time is believed to be many ordersof magnitude greater (107, which is 10 million) than that ofthe higher energy particles in the earth's radiation belts.Only two direct measurement attempts have been reported, oneby the USSR (Lunik) and a recent one by Explorer X, neitherof which has given a complete description of the interplanetaryplasma, in part because of insufficient time in orbit and inpart because of the restricted ranges of the instruments.The plasma probe designed and built at Ames for the S-3is basically a curved-plate electrostatic analyzer with anelectrometer detector. The plate voltage is continuouslyvaried so that the instrument will record the presence ofparticles as a function of their energy (200 ev t o 20 kev,corresponding to the expected 200 to 2,000 km/sec velocityrange).flux for each setting of the plate voltage. Basically, it

works this way: As a charged particle enters the analyzer,by means of a slit in the satellite skin, it finds itself ina curving tunnel. The two sides of this tunnel are metalplates carrying static electric charges, one negative, theother positive. The charged particle is attracted by oneplate and repelled by the other, and so follows a curvedpath down the curved tunnel. If it is moving too slowlyor too rapidly, it runs into one wall or the other. But ifit is moving at just the right speed, it makes its way allthe way to the end and is there detected by a particle counter.Thus, all the particles moving in the right direction to enterthe tunnel and moving with the right speed to get all the waythrough will be detected. Automatically, at fixed intervals,the amount of the stat3 charge on the metal side plates ischanged, so that a different range of energy is required forthe particles to get through.

The electrometer output is a measure of the particle

The complete instrument package is housed in a box '2x3~4inches, and weighs just under one pound. Its total powerconsumption iu 145 milliwatts (one one-thousandth of an ordinarylight bulb).-19-

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Magnetic Field Experiment (Univerpity of New Hampshire, Dr.E. Cahill),The purpose of this experiment is to measure the magnitudeand direction of the earth's magnetic field between 3 and 10earth radii (12,000and 40, OW Mles) ass accurately as possible;

>to investigate the possible termination of the geomagneticfie1.d in the vicinity of 10 earth radii (40,pOO miles); and touse this data ta d e t e m n e the existence of postulated extra-terrestial current systems and magnetic disturbances, particularlyin relation to solar events and changes in particle intensities.Present-day theories of magnetohydrodynamics -- the studyof the relation between the motion of charged particles andthe magnetic field which surrounds them -- say that the plasmawhich flows away from the sun should drag with it the l oca lsolar magnetic field, since the motion of charged particlesnot only responds to but also creates magnetic fields. Themathematical description of this interaction between the stream

of charged particles leaving the sun and the magnetic fieldwhich surrounds the sun is extremely complicated. The theorieswhich have been used to describe these phenomena are incompleteand often contradictory.against the mathematical difficulties, soientists are forced toassume various characteristics of the interplanetary plasma.However, at present, there is no way of determlning'whetheror not these assumptions are realistic.

In order to make any headway at all

The results of the S-3 measurements on the magnetic fieldsin interplanetary space will be used to check the conclusionsof the various theories now existing, and will also be usedto provide additional and more valid assumptions for the creationof a more conclusive theory.

Several earth satellite measurements, and measurementstaken by the probes, Pioneer I, Pioneer V, and Explorer X havegiven us a few pieces of information about the field at greatdistances from the earth, and information about the nature ofthe magnetic field in the space between the earth and themoon. It is in this latter region of space that the inter-planetary field and the earth's magnetic field interact toform a complicated boundary. Some scien$ists believe thatthe detailed structure of this boundary may explain the creationof the Van Allen Radiation Belts. Results from Explorer v1:and Pioneer V suggest that the magnetic field in this regionmay be perturbed by a vast current ring encircling the earthoutside of the major radiation belts. The particles in thiscurrent may have been detected by Soviet space probes.

The S-3 will study the undisturbed magnetic field of theearth to determine if the field is temninated by solar windpressure within the range of measurement. Data will be studied-20-


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for evidence of t h e r i n g cur ren t , revealed by Pioraeer V.Varia t ions of sun,li a current , both i n s p e c t r a l posIZtion andi n t i m e , w i l l be inves t iga ted . Data a l s o wlll be examlned f o rrapid changes of the magnetic f i e l d i n t ime. These might bein te rp re ted toge the r w i t h information from ground magneticobservator ies , as evidence f o r th e propagation of hydromagneticwaves. Time v a r i a t i o n s i n the magnet ic f ie ld w i l l be comparedw i t h surface magnetic measurements and w i t h records of s o l a ra c t i v i t y t o d i sc o v w p o ss i b le c o r r e l a t i o n s , p a r t i c u l a r l y d ur in gmagnetic storms. The t i m e v a r i at i o n s i n the f i e l d w i l l becompared w i t h t h e v a ri a t i o ns i n p a r t i c l e i n t e n s i t i e s for f ixedlocat ions between the two neasurements. I n add it io n, t h ed i r e c t i o n o f -I;h.e magnetic f i e i d w i l l be a v a i l a b l e f o r comparisonw i t h d i r e c t i o n a l c h a r a c t e r i s t i c s of t h e p a r t i c l e i n t e n si t i e s .Comparison of nagnetis f i e l d data from S-3 and a l so t h eRanger-type space probe w i l l e n a b l e s c i e n t i s t s t o s tudy g rad ien t sof magnetic f i e l d s ane the r a t e of propagation of magnetic d i s -turbances, and how solar wrrida eTfect t h e f i e l d .Thus, data from the mzgnetometer measurement w i l l be offundamental importnrxe L:? in t sTpre t ing the r e s u l t s o f thevarious charged pa:L,tlicles ex7eriments which a r e c a r r ie d ORboard S-3. The combins.t-;on of charged narticle measurementsand magnetic f i e 16 measurements will be of tremendous value i nadvancing our knowledge i n th e beh avio r of t h e sun and i t s e f f e c t supon phenomena here on the su r f ac e of t h e e a r t h ,The flux-gate rmgnetoomt$m i s a, thre e-c ore device . Eachof t h e t h r e e orthogonal SWISOTS 2roduce an output voltagepropor t iona l t o the magnitude of t h e component of the combinedmagnetic f ie lr ! a long tha t sensor. The output voltages of th eth ree sensors each occupy a, s e p v a t e channel and are combineda f t e r r ecep t ion t o cozr:: t h e tc;tal magnetic f ie ld! vector . Therange of measurerimit i s from a f e w ganunas t o 1,000 gammas.Accuracy i s p l u s o r qninus 10 gammas. Magnetometer instru-menta tion cons l s t s of ,wo packages: a sensor package 3x3x4.Sin ch es , and an eecti-onics 2ackage _?x4x6+ in ch es . The f i r s tweighs 640 grams and t h e l a 3 t e r 760 grams. Total power con-sumption i s 405 nill!-va-btsu

Trapped Pa r t i c l e R a d i a t i o n ( S t a t e Univer s i ty of Iowa, D r . BrianJ . OsBrien)The purpose of th i s expe?lment I s t o measure charac t er -

i s t i c s of p a r t i c l e r a di a t i o n -- t ra pp ed p a r t i c l e s , s o l a rpa r t i cl es , and cosmic mys ---o m r t h e en k ir e s p ac e cr a ft o r b i tt o de te rmine the l r fluxes and energies and s p a t i a l and t e m -poral dependence.Inst rum enta tio n Coi~slSCvS of fo u r g ei ge r cou nt er s and th reecadmium sulphide cells. A Geiger-Mueller counter, s imilar t othose w i t h which Professor Van Allen d iscovered the ex is tence

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of" t h e v a s t b e l t s of rad ia t ion around t h e ea r th w i l l d e t e c tpa r t i c l e s a r r iv ing f rom every d i r ec t ion . I t w i l l measure protonsabove 20 Mev and e l e c t r o n s above 2 M e V ,The three o t h e r tubes make up a n elec t ron spect rometer .One geiger de te ct s ele ct ron s between about 40 and 55 kev which

are focused onto i t by being def lec ted by the f i e l d of a smallmagnet. Thi s i s heavi ly sh ie lded , bu t another geiger i s housedalong s ide i n i d e n t i c a l s h ie ld in g t o moni tor pen et ra t i ngr a d i a t i o n s (protons above 50 M e V , electrons above 10 Mev). Thet h i r d geiger measures electrons between 90-100 'kev,devices which change t h e i r e l e c t r i c + r e s i s t a n c e i n p ro po rt io nt o the ra te a t which they are be ing bombarded by chargedp a r t i c l e s ,vo l t age to the c r y s t a l , Charge f lowing through the c r y s t a lb u i l d s up on a condenser un t i l a c r i t i c a l vol tage i s reached andthe condenser discharges through a glow tub e, The r a t e of d i s -charge thus increases w i t h the conductivity and hence theion iza t ion ene rgy lo s t i n t h e c r y s t a l also inc reases the r a t e ofdischarge. These c r y s t a l s are uncovered and c a n d e t e c t p a r t i c l e st o very low energies-protons and e l e c t r o n s down to ene rg ies o ft h e order of 100 e v o r l e s s , One cadmium su lph ide ce l l measurest h e t o t a l energy f lux o f both protons and electrons on it. Anotherc e l l has a magnet which de f l ec ts el ec tr ons below se vera l hundredkev from st r i k in g the c rys t a l , performing as a low-energy protond e t e c t o r , A t h i r d cadmium sulphide c e l l look s i n th e same narrowregion of th e sky as do t h e other two, This , however, i s f i t t e dw i t h a t ransparent s h i e l d so t h a t c o r r e c t i o n s f o r the e f f e c t s o fl i g h t ( e a r t h l i g h t o r sunleght) s t r i k i n g t h e o t h e r two c e l l s may?e made accura te ly ,encoder, The spectrometer and the cadmium sulph ide c e l l s viewnarrow posi t ions of the sky perpendicular to the axis of sp in oft h e s a t e l l i t e , The detectors are selected--two a t a time--tofeed two sca l ing un i t s f o r 10 ,24 seconds , The scalers each a r eread out twice and the information telemetered as a sequence ofb i n a r y b i t s , T h e s c a l e r s are then r e se t t o z e r o and the nextp a i r o f d e t e c t o r s s e l e c t e d . This information i s then f ed to anappropr ia te d i g i t a l su b c a r r i e r o s c i l l a t o r f o r t ra nsm is si on ontelemetry channels,i n 10.24 seconds--a maximum counting r a t e o f about 25,000counts/seconds. The three cadmium sul phid e c e l l s weigh 494grams; t h e Geiger-Mueller counter3 292 rams, and the threeand hardware weigh 1540 grams,

The cadshium su lph ide c e l l s are sol id-state semi-conductorThe conduct iv i ty i s measured by applying a steady

, S t a t e Universi ty of Iowa instru mentat ion al so includes an

The s to rage capac ity of th e apparatus i s f o r 218 counts

geigers i n t h e elec t ron spect rometer , 783 grams, The encoder- 22 -


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Cosmic Ray Experiments (GoddaFd Space Flight Center, Dr, Frank B.Mc k] na1dAt the present tine, the m o s Z fanportant problems in cosmicrays are the nature of the aczelerating mechanism and the natureof the modulation mechanism which produce the 11-year s o l a r cycle

variation and the Forbush type decrease, An accelerating mechanismwhich can produce particles with energLes up t o 1018 ev and amodulation [email protected] which can influence particles with energiesgreater than 10 ev have important astrophysical implications.The theoretical explanations f o r these phenomena are hopelesslyinadequate at this time and. additional experhental informationis needed.The sun is a very impcrtant source o f low energy cosmicrays and the cosmic ray moCulat ion mechanism appears to beintimately connected t o solar events, If we can understand themechanism by which solar cosmic rays are produced and theconnection between s o l a r activity and c o sm i c ray intensity changes,

then we will probably have the necessary clues to understand thegeneral origin of cosmic rays.The S-3's cosmic ray monitoring prograrn beyond the effectsof the earth's magnetic field permits the production and modulationof cosmic rays to be studied with the same set of experiments. Theprogram will measure %he charge spectra and the energy spectra ofthe cosmic radiation as a function of dfstance from the earth,time and direction. Al?d a?_ncemany of the effects of solar relatedphenomena are transmftted via the emissicn of a solar plasma or asolar wind, scientists f e e l the S-3 1s o f the greatest importancein making simultaneous magnetiL f i e l d and plasma measurements,The cosmic, ray package c o n a f s t s of three basic detectionunits: a Double Telescope, a Single Crysta l Detector, and a GMTelescope. The first d e t e c h r is a double scintillati3n-countertelescope in which the pulse f m m one of two coun5ers is selectedfor a given event. Ynis w i t provides: the t o t a l cosmic ray f lux;the flux of fast prstom w i t h energies greater than TOO Mev; theproton differential cne-gy spectran i n t h s saegl.cn 70-750 MeV; andthe low energy portion of the Alpha particle differential energyspectrum. The double t e l e z t c p e is 20 %r.ches long, has a 2,5inch diameter; weighs 765 g r m s and requires l,25 watts of power.When a particle traverm-e ?he two scintillators acoincidence is formed and %he pulse height from one of thescintillation counters f s processed by a channel analyzer, Datais accumulated in the a.nalyzer's magnetic core memory for fourminutes and is then r d out serially, Read-aut is nondestructive.Channel capacity is ZT g pel. channel,

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In order to extend the proton energy spectra data downto 1 MeV, a thin cesium iodide scintillation counter is usedas the second detection unit. The pulse height distributionof the incident particles is obtained in the region 100 Kevto 20 Mev by means of a sliding channel pulse height analyzer,which basically determines the size of each pulse and storesit in an appropriate channel for later transmission to theground. The shape of a pulse from a scintillation counter canbe used to distinguish between protons and electrons. Thisunit also provides information on low energy solar gamma rays.This detector, or scintillation counter, is connected t oan integral discriminator whose bias is furnished by an eight-level staircase generator.box) is subcommutated between the eight levels and two Geigercounter inputs of the GM telescope. In each case the actualnumber of counts per unit time is transmitted. Appropriateidentification is also provided for each readout. When oneinput of the multi-channel analyzer is readout, the other inputs

are disconnected.has a length of 4 inches, a diameter of 2.5 inches and requires.200 watts o f power.

A data accumulator (cosmic ray logic

This single crystal detector weighs 615 grams,The third unit, called a GM telescope, consi ts of twogeiger counters.The effective geometric factors of these counters are severalorders of magnitude larger than those in the State Universityof Iowa package and are intended to be cosmic ray monitors.The rate of the shielded, and the coincidence rate of the twocounters is telemetered. These units furnish a check on theinformation received from the scintillation counter units.This unit weighs 400 grams, has a length of 5.2 inches, a diam-

eter of 2.5 Inches and requires .3OO watts of power.Ion Electron Detector (Goddard Space Flight Center, Leo R. Davis)energy as a function of direction, time and position below,in, and above the V a n Allen Radiation Belts. This detectoris most sensitive to the low energy partlcles which have notbeen directly measured to date and yet have been indicated tobe in the inner and outer radiation belts.

One is shielded with 2 grams/cmB of material.

This detector will measure particle fluxes, types and

The ion-electron scintillation detector consists of apowder phosphor, on a photo-multiplier tube which is locatedbehind a stepping absorber wheel. The dc current and pulsecounting rates are measured simultaneously for each absorberpositi n.

Ion counting rates for two trigger levels are registeredfor seven absorber thicknesses from which ion types and energyspectra can be deduced. In these measurements electrons are/ -24-


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discr iminated against by t h e phosphor thinness (5mg/cm2) andthe phosphor ch a ra c t e r i s t i c of the emit ted l igh t decay timebeing inverse ly propor t ional t o the square of the i o n i z a t i o ndens i ty .The electron energy f l u x i s obta ined by sc a t te r in g t h e

inc iden t e l ec t rons o f f a gold p l a t e ( ions w i l l be absorbed)i n t o the phosphored pho to -mu lti pl ier tub e from which dc c u r r e n t sar e measured. Electron energy sp ect ra can be deduced by com-par ing the responses from s i x absorber thicknesses.The t o t a l e ner gy f l u x i s obtained for seven absorberthicknesses by measuring the photo-mult ipl ier dc current .The i o n d e t e c t o r i s operat ive over the energy range of100 Kev t o 1 Mev f o r protons w i t h m a x i m u m counting r a t e s of lo5c ps i n each channel .The e l e c t r o n d e t e c t o r w i t h a dynamic range of lo5 i s

opera t ive for e lec t rons be tween 10 Kev and 100 Kev.pho3o-mu ltiplier voltage, th e minimum det ec ta bl e energy i s10' ergs/seconds. For averageThe t o t a l e n e r g y f l u x detector w i t h a dynamic range of10 i s operat ive over t h e energy range of 30 Kev t o 1 Mev f o rprotons, and 10 Kev t o 100 Kev f o r e le c t ro ns . For average va luesof ph to-mul t ip l ie r vo l tage , th e minimum detectable flux i s2x10-8 ergs/seconds. The d e t e c t or has a t o t a l we ight of 1362grams and i s housed In a 5 3/13 x 6 7/8 x 3 1/8 inch conta iner .

5

Sola r C e l l Ekperiment (Coddard Space Flight Center, @. .Longanecker)This experfment w i l l measure th e e f fe c t s of the d e t e r i -ora t ion of so la r c e l l s caused by d ipect exposure t o t h er a d i at i o n i n the Van Allen B e l t s .The experiment con si st s of fou r s t r i p s of s i l i c o n s o l a rc e l l s , w i t h 10 c e l l s p e r strip, mounted on t h e sur face of thespacec raf t . One s t r i p of 10 c e l l s i s unprotected while theremainingth ic k g l as s respect ive ly . During the l i f e of the spacec ra f ti t w i l l be poss ib le t o compare the e f f ec t iveness o f theg l a s s f i l t e r s i n preventi ng degr*adatfon of the s o l a r c e l l sdue t o r a d i a t i o n .

th ree strips are pro tec ted by 3, 20 and 60 mil

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s-3 energetic particles satellite press kit

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