iqsy press kit

8/8/2019 IQSY Press Kit

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W S NATIONAL AERONAUTICS AND SPACE ADMINISTRATION TELS WO 2-4155*-N-TONAL WASHINGTON, D.C. 20546 WO 1-6925FOR RELEASE. TUESDAY P.M.November 16, 1965RELEASE NO: 65-352

NASA, NAVAL LABTO LAUNCH IQSYSOLAR EXPLORER

The National Aeronautics and Space Administration and theNaval Research Laboratory will launch no earlier than Nov. 18a satellite to measure and monitor solar x-ray emissions duringthe final portion of the 1964-65 International Quiet Sun Year(IQSY).

The IQSY Solar Explorer, developed by NRL, will be launchedfrom NASA's Wallops Station, Wallops Island, Va., on a four-.stage Scout.

The international scientific community has been invitedto acquire data directly from the satellite. Information ob-tained will be correlated internationally by scientists con-ducting studies related to IQSY, a period when solar activityis at a minimum.

The IQSY Solar Explorer, by measuring and monitoring solarX-ray emissions and providing immediate data to interested sci-entists, has the potential for improving forecasts of iono-spheric conditions that affect short-wave radio communicationsand for developing a warning system for major solar flares whichproduce intense proton emissions hazardous to manned activities ;in space.-_ _ mre -1--26- -


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-2-The 125-pound spacecraft consists of two 24-inch hemi-

spheres separated by an equatorial band in which are installed12 photometers for measuring solar X-ray and ultravioletemisscions. T-lectrical power is supplied by solar cells mountedon the hemispheres.

The spiti-#; abilized satellite will be placed into a 430-by-630 mile orbit inclined 60 degrees to the Equator. Ex-pectecd active lifetime is one year.

The spacecraft will complement and continue the scientificmissions of other NASA spacecraft and the NRL's two Solar Rad-iation (SOLH,0])) satellites: 1964-OlD, launched in January 1964and 9 6 5-16D, launched in March 1965.

NASA's Office of Space Science and Applications (OSSA) hasoverall direction of the IQSY Solar Explorer and Wallops Stationis responsible for project coordination and launch operations.

Satellite commands and acquisition of scientific data willbe carried out by NRL through its Tracking and Command Stationin Hybla Valley, Va.

NASA's Goddard Space Flight Center, Greenbelt, Md., willbe responsible for tracking the satellite during its usefullife and will support NRL in acquisition'ot teleimetered datafrom the satellite.

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-3- IThe Scout launch vehicle is under the management Of NASA's

Langley Research Center, Hampton, Va.

(Background information follows)* -

BACKGROUND

The Earth is a body immersed in the atmosphere of a star-- 4the Sun. Radiation from the Sun controls the environment ofEarth, of other solar system planets and of interplanetaryspace. Because most emissions of radiation from the Sun arevariable, the environment of the Earth is variable.

These is a pattern to solar activity, with a maximum anda minimum occurring every 11 years, and a similar cyclic varn-ation is evident in the properties of the Earth's atmosphere.

The present period is one of minimum solar activity. Thenext period of maximum activity will be from 1967 to 1972.

Solar Flare'Important

The solar flare appears to be the most important part of,the solar activity insofar as effect upon the environment ofthe Earth is concerned. A flare is a sudden brightening of anarea of the solar surface occurring in a few minutes and thenslowly decaying over a period of hours,

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-.-The X-rays and enhanced ultraviolet light emitted during

the life of a flare increase the ionization in the Earth's iono-sphere and disrupt short-wave radio communications.The largest flares also emit great numbers of high energy

protons which increase the radiation levels in interplanetaryspace and over the Earth's poles. Greater knowledge of theradiation emitted by the Sun is required to understand theseinteractions between solar events and the Earth's upper atmos-phere and ionosphere.

In addition to effects on interplanetary space, the Sunitself is an interesting astronomical object. It is the onlystar whose surface characteristics we can resolve and study.Knowledge gained by studying the Sun will help astrophysiciststo understand and interpret the data from other stars.

Valueof Space ResearchThe techniques of space research permit scientists to ex-

pand solar studies two ways: They can increase the resolvingpower of their telescopes through the elimination of atmos-pheric distortion, and they can observe many more decades(groupings) of the electromagnetic spectrum.

The Sun emits electromagnetic radiation (light, radio andinfrared radiation) in 16 decades of wavelength or "color".

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Of these 16 decades, only a fraction of one decade is thevisible light that a human eye can see. Three other decadeslie in the radio portion of the spectrum which can be observedon the ground.

The rest of the solar radiation is absorbed in the Earth'satmosphere and can be observed only with instruments above theatmosphere.

The absorbed portions of the spectrum are doubly important.They are the portions which vary with solar activity. In orderto understand the mechanism of a solar flare, studies of theultraviolet and X-rays emitted during a flare (both of whichare absorbed in the atmosphere) must be made. Furthermore,since the radiation is absorbed in the upper atmosphere, theseportions of the solar radiation control the nature of the upperatmosphere.

How Satellites Help

Satellites contribute to studies of solar phenomena inthree major ways. They make possible the study of the ultra-violet, X-ray and gamma ray radiation which is absorbed in theatmosphere; they permit continuous monitoring of this radiationduring solar cycles of activity; and they provide higher reso-lution- than ground equipment through the Elimination of' atmos-pheric scattering.

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The primary reason for the solar studies is to meet theoverall objective to expand human knowledge of space phenomena.While these are exciting and important reasons for the workthere are also practical benefits to be gained.

Knowledge of solar radiation and its effects on the ter-restrial environment, together with continuous monitoring ofthe entire spectrum of' solar radiation, should result in Sig-nificant advances in the understanding of, and ultimate controlover weather.

If significant advance signs of solar activity can befound and used to predict solar flares, this discovery will bea major contribution to the communications industry, meteorologyand manned space flights.

Several Techniques Tried

In recent years portions of the solar spectrum of radia-tions have been observed by ground-based monitors, balloon-borne instruments, high-flying aircraft, sounding rocket flights,deep space probes, and satellites. Scientists from industry,universities, and several Government agencies have engaged inthese efforts to unlock the Sun's secrets.

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-7-The Naval Research Laboratory began in 194 9 a program of

observation of solar ultraviolet and X-ray emissions in whichthe V-2 and, later, Aerobee sounding rockets were used to liftsensitive instruments (spectrographs and photometers) above theabsorbing layers of the atmosphere.

In 1956, NRL began trying balloon-launched rockets,ROCKOONS, in a direct-measurement attempt to test the theorythat solar X-rays weze responsible for sudden ionospheric dis-turbances (SIDrj) during solar flares.

A rocket fired during a solar flare July 20, 1956 indi-cated a surprisingly high intensity of X-rays between altitudesof 75 and 100 kilometers (47 to 62 statute miles). Th '-rayflux was the first ever obtained at such short waveleng.ns andat such a low level in the ionosphere.

Sounding Rockets UsefulSubsequent ground-launched sounding rockets gathered con-

siderable new data on X-ray emissions 'during 1957 through 1959.Rocket measurementb were made during three solar flares each ofwhich was accompanied by a large SID.

Sounding roc1et experience by NRL, NASA and others providedthe brief glimpses of the Sun's spectrum necessary to guide de-velopment of satellite It.strumentation.

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-8-In the study or such spasmodic events as solar flares,

however, the sounding rockets have three handicaps: They can-not be launched quickly enough to see the early phases of flare; ithey cannot stay above the Earth's atmosphere long enough tomeasure time variations of solar X-ray and ultraviolet emissions;and it is difficult to keep instruments pointed at the Sun dueto roll and yaw.

Therefore, scientists turned to satellites capable of pro-viding a stable platform for continuous solar monitoring.

In June 1960, the SR-I, designed and built by NRL, becamethe first successful solar X-ray monitoring satellite. BecauseX-ray monitoring could be conducted only when SR-I passed overa telemetry station, the experiment depended on NASA for track-ing and data acquisition.

SR-I Results Significant

Despite modest capabilities, 577 telemetry records wereobtained from SR-I between June 22 and Nov. 1, 1960. One hun-dred of these WI - wed measurable X-ray fluxes.

Results were significant. SR-I confirmed the hypothesisthat solar X-rays cause sudden disturbances in the ionosphereduring flares and determined the intensity necessary to triggerthe changes.

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-9-It also established that active prominence regions, bright

surges on the edge of the Sun, and certain solar-edge (limb)flares have the same characteristics as major disk flares. Thedisk is the central portion of the Sun as viewed from Earth,

Dhta from SR-I showed that solar X-ray fluxes provide avery sensitive measure of solar activity and can change sig-nificantly within one minute. It was found that long-durationX-ray events of1 oderate intensity can accompany rising promi-nences on the solar limb. Prominences are streams of cool gasthat surge into the hot corona.

The second satellite in the SR series failed to achieve.orbit and the third, SR-III, launched in June 1961, went intoa tumbling mode that made data reduction difficult. Nevertheless,some of the data from SR-III has been reduced and found useful.

Variations DisclosedThe experiments of SR-I and SR-III made it evident that

X-ray emission spectra vary greatly from one flare to anotherand with time during a single flare event.

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-10-The most successful satellite of the SR series wa6

launched in January 1964 and became 1964-OlD. During periods.or good alignment relative to the Sun, the satellite hasprovided 200 minutes per day oif direct solar observations with-measurements of solar X-ray emissions in the spectrum bands of1-8, 8-12, and 44-60 angstroms. The angstrom (A) s a tinymeasure of wavelength: 3,200 A equals about 13 one millionthof an inch.

The 1964-OlD is still operating and its experiment datais being analyzed. The 44-60 A wavelength band has provedespecially sensitive to even the smallest solar event and itsobserved flux has been correlated to plage phenomena. Plages arebright, hot areas that appear on the Sun's photosphere. Thephotosphere is the visible disk of the Sun.

Since NASA was established in October 1958, there has beena close working relationship between NRL and NASA personnelin numerous scientific projects of mutual interest. Vanguard II,the first satellite launched by NASA (February i959), wasdeveloped by an NRL team that was transferred to NASA,

Among many former NRL scientists and project managers nowwith NASA in key positions is Dr. Homer E. Newell, AssociateAdministrator for Space Science and Applications.

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Much of the NASA-NRL cooperation and interagency supporthas been in efforts related to solar phy-;ics. In the area ofscientific exploration, an understanding of the universe, withparticular emphasis on the solar system, remains the all-encom-passing NASA objective.

OSOs Have Major RoleA series of Orbiting Solar Observatories has a major role

in NASA's solar physics program which is directedat, determiningand defining the physical processes by which the Sun influencesthe Earth and its space environment and at advancing knowledgeof the Sun's structure and behavior.

The first of eight planned OSOs was launched March 7, 1962and the 13 scientific experiments on OSO I provided useful datafo r more than two years. The second, OSO II, was launchedFeb. 3, 1965. The third failed to achieve orbit Aug. 25., 1965

The OSOs weigh about 600 pounds and are designed primarilyas highly stabilized platforms for precision pointing of a largenumber of solar-oriented instruments.

The IQSY Solar Explorer complements and extends otherNASA-sponsored launches which include solar monitoring. SimilarNRL experiments on OSO II had nominal lifetimes of about sixmonths and are no longer operati.;e.

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The IQSY Solar Explorer is unique in that it can providereal-time (immediate) data acquisition worldwide to anyone whochooses to receive it.

ObJectives of IQSY-SEThe IQSY Solar Explorer, designed and built by NR.,

will continue the solar X-ray monitoring program begun bySR-I. Main objectives are to:

1. Monitor the Sun's energetic X-ray emission withstandardized X-ray photometers;

2. Measure the time history of X-ray emission intensityand spectral equality of solar flare emissions and to corre-late these measurements with those of optical and radioground-based observatories; and

3. Provide real-time solar monitoring information toall interested participants in the IQSY program.

SPACECRAFT DESCRIPTIONThe spacecraft consists of two 24-inch diameter hemi-

spheres separated by a 31 inch equatorial band in which aremounted 12 photometers with magnets to shield the photometersfrom saturation by Van Allen radiation belt electrons. Alsomounted on the equatorial band are four antennas for telemetrypurposes,

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Six flat circular panels covered with solar cells aremounted symetrically on the hemispheres.

Electric power converted from solar energy by the cellsis available to charge the nickel-cadmium batteries and tooperate all spacecraft electrical systems. The symetricalarrangement of the 11-inch diameter panels assures adequatepower regardless of the Sun angle.

The silicon solar cells will supply six watts of power.The portion of the shell not covered with solar cells is high-ly polished and has a thermal control coating applied. Thiswill keep the internal temperature between 10 and 40 degreesCentigrade.

Two low-thrust vapor jets are located adjacent to theequatorial band to maintain spin rate and control of thespin axis. The spacecraft is planned to be spin stabilized atabout one revolution per second. Two Sun sensors located 180degrees apart generate properly timed Jet pulses to precessthe spin axis as necessary.

Output Of four photometers can be switched to the low-power Digital Data Storage System (DDSS). The digitized datacan be read out over a special transmitter by command when thesatellite passes near the NRL ground facility,

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Radio equipment on the satellite includes an analogtransmitter fo r continuous operation, a digital transmitterto operate on command only, the four-element antenna system,and two command receivers connected to a decoder system forplacing the spacecraft and its experiments in desired operatingmodes.

The telemetry system consists of six subcarrier oscillators.Their mixed output modulates a transmitter which will sendboth housekeeping and X-ray data.

A magnetic core memory system will collect data fromfour X-ray detectors over a 24-hour period and then, on command,transmit the digitized data for five minutes to the NEL groundstation. After that the system is reset to collect data foranother 24-hour stretch.

SOLAR RADIATION MEASUREMENTSAll radiant energyincluding that from the Sun, is

emitted in many diverse forms and over a tremendous range offrequencies, or wavelengths. All these forms of radiantenergy are electromagnetic in nature, obey the same basic lawsand travel through space at the speed of light (about 186,300miles per second). They differ in wavelength, origin and theways in which they manifest themselves.

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Wavelength Type of Number of Type of(In angstroms) Emission Photometers Photometers44 to 60 X-ray one Ion Chamber1080 to 1350 Ultra- two Ion chamber (2 inviolet parallel)1225 to 1350 Ultra- two Ion chamber (2 inviolet parallel)(*--Each 1-8A and 8-16A photometer has a different degree ofsensitivity to cover a broad range of flux values and to permitthe correlation and extension of similar measurements onearlier satellites.)

The measurements are made in different but overlappingX-ray bands so that comparison of the different photometeroutputs can be employed to construct a model of the solarX-ray spectrum and to provide an instantaneous indication ofspectral changes with solar activity.

Satellite-obtained data on the daily average X-ray fluxwill be provided to the Institute for TelecommunicationsSciences and Aeronomy, Boulder, Colorado, for rapid publication.

SCOUT LAUNCH VEHICLE

Scout is a four stage solid propellant rocket capableof carrying payloads of varying sizes on orbital, space probeor reentry missions. It is 72 feet long and weighs about 20tons at lift-off.

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Scout was developed and is managed by NASAls LangleyResearch Center, Hampton, Va. Prime contractor is Ling-Temco-Vought, Inc., Dallas, Texas.

Its four motors are interlocked with transition sectionswhich contain guidance, control, ignition, instrumentationsystems,. separation mechanisms, and the spin motors requiredto stabilize the fourth stage. Guidance is provided by astrapped-down gyro system and control is achieved by a com-bination of aerodynamic surfaces, jet vanes and hydrogenperoxide jets.

Scout is capable of placing a 320-pound payload into a300 nautical mile orbit or of carrying a 100-pound scientificpackage 18,000 miles from Earth.

Scout stages include the following motors:First stage: Algol llB

- 100,944 pounds thrust, burning 80 seconds.Second stage: Castor 1- 63,109 pounds thrust, burning 46 seconds.Third stage: Antares (X-259)

- 22,606 pounds thrust, burning 34.9 se ..ds,Fourth stage: Altair 11E6 (X-258)

- 6,414 pounds thrust, burning 22.2 seconds.

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IQSY SOLAR EXILORER PROJECT TEAMFor the National Aeronautics and Space Administration:

M. J. Aucremanne (Headquarters) Program Manager.J. M. Weldon (Headquarters) Program Scientist.T. W. Perry (Wallops) Project Coordinator.W. A, Guild (Headquarters) Scout Program Manager. iE. D. Schult (Langley) Head, Scout Project Office.

For the U. S. Naval Research Laboratory:R. W. Kreplin, Project Scientist.P. G. Wilhelm, Project Manager.H. Friedman, Scientific Investigator.T. A. Chubb, Scientific Investigator.

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SOLAR AREAS OF SCIENTIFIC INTERESTSUNSroTSCOOL, IARK AREAS SOLAR WIND- smAIsCENTERNr) IN STRONG. LOCAL OF CHARGED PARTICLES; MOSTLYMAGI:TIC FIELDS; LAST ELECTRONS AN D PROTONS; CANFEW DAYS TO 3 MONTHS; PRODUCE GFOMAGNEliC STC)RSUMBRA SDARK CORE; AN D IONOSPHERE DISTURBANCESPENUMBtA IS OUTER AREA

SOLAR WIND /PROMINENCES(CONDENSED SIREAMSOF COOL GAS, ABOUTCHRO1iOSPHERE 10,000 DEGREES KELVIN, WITHIN HOT CORONA)(VISIBLE DURING LCUI ES ORWITH SPECIAL TELESCOfES;

TH!N TRANSITION LAYER . ,BTWEEN COOL PHOTOSIHEREAN D HO T CORtONA) < /\ l AGLN C EAk (BRIGS1T, HOT =REACTIONS INWHICH 1 jlsF DR.HYDROGEN IS CHANGED PHOTOSHERE) WSOOR WITHOSHECIAUMTETEMCORE-

TO TUNPATEENTEIO5 T2 MILLON DNMILL IONEDEGPEES KELVINO( MILLION F). (Ll

ENRG F A AUSUNPOT(VISISUEDUlItG ECLPSE:S / 1L \ IN Pt.E) r ,R ITNH STECIAL TEGEHCOPES; O S YIONIZED GASES CORRltESPONDNG -|S D2MILLO DEGREEOS KELVI PHOTOS HERE SOLAR FLAREAS=U 3 MILIONi DEGIE1 (VElRY UBlGltT VISIBL DISC WITH (SUDDEN TELEASE OF TREMEMOUSFAHENHEIT GAWNULARAPRNG SURFACE ONsENERIGY FltM MU^J A SUNSPOT;WHICH SUNS OTS AND PLAGES OCCUR, SPEWS FORTH CHARGD PARMLES, RtAYS.MARKED BY STRONG, T7URBLENT MOTIONS, AN D IONIZED GASES THAT AFFECT THEUKE BOILING LQUID; ITS UIGHT REACHES EARTH ENVICNMAENT WITHIN A FEWEARTH IN 8 MINUTES; TEMPERAJURE MINUTES AND FOR DAYS AFTEWARD;5,900 DEGREES KELVIN OR ABOUT 11,000 CA N DISRUPT LONG DISTANCE RADIO ANDDEGREES FAHRENHEIT; EDGE IS CALLED THE LIMB) TELElHONE COMMUNICATIONS)

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1225-13504 ULTRAVIOLET DETECTOR NUTATION SOLAR ASPECT DETECTORATTITUDE CONTROL AND 8-16A DETECTORSPIN REPLENISHMENT \ IE/CONOZZLE1-8A DETECTORS 0.5-3 AN D I-eA

DETECTOR

SOLAR CELL

t-84 AND 0.5-34 0-20.1 X-RAYDETECTOR DETECTOR8-16 A X-RAY DETECTOR 44-60A X-RAYSOLAR ASPECT DETECTOR DETECTORNTTODAPR1080-13501 *UTATION DAMPER -- LTRAVIOLET DETECTORTOP VIEW

TELEMETRY ANTENNAS

( YO-YO DE-SPINSYSTEM,PAYLOADENVELOPE------

NUTATION DAMPER | i\-SEPARATION FLANGE

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