A Survey of Space Applications

8/7/2019 A Survey of Space Applications

1/138

o_ (ACCESS(ON NUMBER)

(PAGES)5

(NASA CR OR TMX OR AD NUMBER)

.j

ications

" fo theb e_t4all...en manklnd"NATIONAL AERONAUTICS AND SPACE ADMINISTRATION


2/138

i NASA SP-142

A SURVEY OF SPACE APPLICATIONS"...fo_thebenefe'tofff mank_nd,

Space Applications Programs OfficeOffice of Space Science and Applications

Scientific and Technical Information DivisionOFFICE OF TECHNOLOGY UTILIZATIONNATIONAL AERONAUTICS AND SPACE April 1967ADMINISTRATIONWashington, D.C.


3/138

For sale by the Superintendent of Documents,U.S. Government Printing Office, Washington, D.C. 20402Price 70 cents


4/138

FOREWORDThe second half of the 20th century is characterized by an explosive in-crease in the powerful instruments available to mankind in the shaping of itsdestiny, for either good or for evil. New technologies have grown so rapidlyas to offer a wide array of capabilities from which the leaders of the society

are able to choose their tools in the pursuit of their goals. Significant amongthese are the teclmologies that have been expanded or created in response tothe drives for the exploration of space, an exploration not yet 10 years old.But, if our age is characterized by the burgeoning of new forms of power,so has the history of our Nation always reflected the search for wisdom in theuse of that power. One of the major avenues of intellectual and programeffort that have guided the National Aeronautics and Space Administrationhas been the concept, at first unproved but now clearly valid, that space sys-tems can provide unique, direct benefits to man, benefits not before possible oreconomically feasible. We do not yet know the full range and scope of thepossibilities that manned and unmanned spaz_cra_ open for the service ofman. Those few particular applications upon which the United States hasconcentrated in the past have borne out that promise: Communications, navi-gation, geodetic, and meteorological space systems are operational today andtheir existence, once exotic, has already become woven into the permanentfabric of our society.It is clear that many potential applications exist; it is not clear todaywhich of these should be pursued, nor on what time scale, nor at what cost.Beginning in the summer of 1967, the National Academy of Sciences is con-ducting a study that will bring to bear upon these questions eminent inde,pendent scientific and technical talent. NASA is pleased to encourage andparticipate in such a searching inquiry, since only through such a free ex-change of ideas in a free society can true progress be made or a sound basisfor the major decisions of the future laid down. This survey of space appli-cations for the benefit of man represents the current NASA thinking, has in-corporated as many as possible of the views of our colleagues working in thoseareas which we feel space can s_rve, and is published as a source and docu-ment baseline for continuing discussion and inquiry in this important area.

JAMES E. WEnB,Administrator,

NationaZ A eronautics and Space Administration.o11|


5/138

ACKNOWLEDGMENTWe wish to express our grateful appreciation to those individuals from

other Agencies who assisted in the preparation and editing of various partsof this Survey, particularly th_ following:A. G. Alexiou ........... Naval Oceanographic Office.W. Fischer ............. U.S. Geological Survey.Dr. Richard Hallgren___ Environmental Science Services Adminis-tration.A. B. Moody ............ Federal Aviation Agency.Dr. A. B. Park .......... U.S. Department of A_owiculture.Robert Porter .......... Department of Health, Education, andWelfare.We wish also to acknowledge the efforts of many others within and out-side of the Government who contributed to the preparation of this document.

iv


6/138

VII.

TABLE OF CONTENTSPage

I. Introduction ............................................... 1II. Communications ........................................... 11Introduction ............................................... 11Small Terminal Multiple Access Communications ............... 11Broadcast Satellites ........................................ 18Satellite Aids to Lunar, Planetary, and Deep Space Communica-tions .................................................... 26Data Collection and Retrieval ................................ 29Data Relay Satellites ....................................... 33III. Earth Resources ............................................ 37Introduction ............................................... 37Agriculture and Forestry Resources ........................... 38Geology and Mineral Resources .............................. 44Geography, Cartography and Cultural Resources ............... 50Hydrology and Water Resources ............................. 56Oceanography .............................................. 62

IV. Geodesy ................................................... 73Introduction ............................................... 73Geometric Geodesy ......................................... 73Gravimetric Geodesy ....................................... 80

V. Meteorology ............................................... 87Introduction ............................................... 87Weather Observation and Prediction .......................... 88Weather Control/Modification ................................ 98Air Pollution ............................................... 105Atmospheric Structure for Model Atmospheres ................. 111

VI. Navigation ................................................. 119Introduction ............................................... 119Position Determination ...................................... 119Traffic Control and Search Rescue ............................ 125Future Applications ......................................... 131Introduction ............................................... 131Reusable Aerospace Transports ............................... 131Orbital Recovery of Material and Equipment for Examination

and Rescue .............................................. 132Space Environment for Therapeutical Purposes ................. 133Industrial Applications of Space Resources .................... 134

V


7/138

I. INTRODUCTIONPURPOSE

This document is a basic contribution of theNational Aeronautics and Space Administra-tion to the projected 1967 summer study onspace applications. The objectives of this sur-vey are:

1. To focus attention on the real andpotential applications of space technologyto civil needs, and2. To summarize work done to date, ef-

fort under way, and program plans; toidentify policy and technical problems yetto be resolved; and to provide a selectedbibliography.SUMMER STUDY OBJECTIVES

The objectives of the summer study are togain the results of a searching interdisciplinaryinquiry by highly qualified independent scien-tists, engineers, and selected experts and gen-eralists into:

1. The feasibility and practicality ofusing space systems for meeting existingand foreseen needs on the Earth.2. The economic tradeoffs of providing

for such needs with space systems, withconventional techniques, or of not provid-ing for them at all.3. The direction and priority of existing,

planned, and recommended U.S. research,development, and operational activities inthis field.

This inquiry must be made in the light of themany policy, legal, social, and political factorsthat impinge upon the use of space systems forcivil applications.

BACKGROUNDThe timeliness of a space applications sum-

mer study is attested to by the unexpectedlyrapid growth of applications during the firstyears of the space era, and the probability that

this growth will continue at the same pace.That this may be the case is indicated by theintense interest in potential applications ex-hibited in several diverse fields of interest, andby the rapid advances in space technology.In view of this rapid expansion of space tech-

nology and of applications thereof, it is con-sidered desirable at this time that the NASAprogram, and our estimates of future applica-tions, be subjected to a critical and impartialreview. The results of such a review will beof great help in pursuing objectives which stemfrom functions assigned to NASA under theNational Aeronautics and Space Act of 1958.These objectives are:To develop and test procedures, instruments,

subsystems, spacecraft, and interpretive tech-niques in the various applications areas.To accomplish long-range studies of the

potential benefits to be gained from_ and theproblems involved in, utilization of space activi-ties for peaceful and scientific purposes for thebenefits of mankind.A comprehensive and meaningful space ap-plications program can help to maintain U.S.

scientific, technological and economic leader-ship and give the space program expression interms readily understandable by laymen andstatesmen as well as scientists and engineers.The U.S. has established an unequalled record

of scientific achievement in space. EquMlyimportant is a U.S. role in space applicationswhich is appreciated by policy maker, business-man, and taxpayer. Return on dollar investedhas a down-to-earth connotation_ and space ap-plications can demonstrate dollar returns inmany of its discipline areas.As will be evident throughout this paper,

space applications are unique in that the NASAapplications R. & D. program, leading to thedevelopment and demonstration of a particulartechnological capability, is only the beginning


8/138

2 A SURVEY OF SPACE APPLICATIONSof a chain of events involving continued use ofthe technology by other agencies to gather data(e.g., meteorological satellites) or to provide aservice (e.g., communications satellites). Be-yond the user of the space technology is a cus-tomer who benefits from the improved serviceresulting from the use of satellites. These dis-tinctions become particularly important in as-sessing the economic benefits of space applica-tions, and in determining the relationships ofthe Agencies involved.At the time of writing, space technology has

already been applied operationally to communi-cations, navigation, meteorology, and geodesy.In each case, operational application has beenpreceded by an extensive research and develop-ment progr,_m which demonstrated the tech-nical feasibility of using satellites. Now, spac_applications are being considered in areas wherethe experimental background is less extensive,or non-existent. Thus, coverage in the variouschapters of this document will vary from ex-trapolgtion from an extensive experimentalbase to speculative extrapolations. Speculationhas been employed deliberately, in assessingfuture possibilities, to stimulate thinking on thedirections in which space applications mightproceed.

APPROACHThe discussion in this survey is divided intothese major sections, within each of which

several specific applications are discussed:Communications.Earth resources.Geodesy.Meteorology.Navigation.Future applications.

Communications includes the use of satel-lites not only for the kinds of service normallyprovided by common carriers and by broad-casters, but also for the kinds of communica-tions and allied services provided by govern-ment and private agencies for the aeronauticaland maritime services, and for other communi-cations services.Earth resources involves the teclmology for

surveying the Earth's natural and cultural(man-made) ro._ources from space. The ma-

jor areas of interest are agriculture and forestry,geology and mineralogy, hydrology and waterresources, geography and and cartogTaphy, andoceanography.Geodesy determines the location of every

point on the surface of the solid Earth and ofthe oceans in a common coordinate system, andmonitors the time variability of the location ofthese points with the maximum accuracy tech-nology allows. While geodesy is a science inits own right, it is included here as an appli-cation because it provides an important serviceto geographers, cartographers, navigators andothers involved in sp'_ce applications.Meteorology covers global and local obser-vation of day and night cloud cover, quantita-tive measurement of atmospheric structure andradiative flux (both contributing to more accu-rate and longer range weather forecasting), de-tecting and analyzing air pollutants, andweather modification and control.Navigation provides, with satellites, a com-munications and traffic control (position deter-

mining) capability for ships and aircraft supe-rior to that now possible with the low, medium,and high frequency systems which must be usedon or over the open ocean.Future applications reflects NASA thinl


9/138

INTRODUCTION 3and geographic coverage. These capabilitiesare weighed against user requirements. Fi-nally, an e_timate is made of the degree to whichexisting methodology can be improved. If thereis still a substantial gap between capabilitiesand requirements, the applicability of spacetechniques is considered.Problems of existing methodology range from

adequacy of synoptic coverage and data reduc-tion to the economic feasibility of surveying orgathering data from extensive land masses andocean areas. For example, to attempt to giveeither the meteorological or oceanographic ana-lysts the kind and type of data coverage desiredis economically unfeasible using conventionaltechniques such as surveillance aircraft, orocean surface vessels, or even deep sea buoys.2. Possible Space ApplicationsThe applicability of satellites for earth-

oriented applications is their ability to see andbe seen by large areas of the Earth--simultane-ously from high altitude, sequentially from lowaltitude. Satellites can survey polar regions,other uninhabited or uninhabitable areas andthe vast oceans, storing the data acquired overthese regions for readout at some later time.Geostationary satellites can provide uninter-rupted service to or observation of vast areas ofthe Earth, while low altitude satellites can pro-vide detailed observations of the Earth, its at-mosphere and its oceans with a frequency andclarity never before possible.Satellites can be equipped with a wide variety

of electromagnetic sensors at visual, infrared, orradio waveleng_chs. In fact, sensors already inuse or under consideration span the entire EMspectrum--long-wave radio receivers to monitorsferics (static caused by lightning) ; microwaveradiometers; infrared sensors at various wave-lengths; and cameras for photographing cloudcover.Satellites can also carry radio repeaters, fora wide variety of communications services rang-ing from the already-existing intercontinentMcommon carrier service, to the collection andrelay _o processing centers of data from sensorsin fixed or moving platforms located on theEarth's surface, on or in the ocean, or in theatmosphere.

3. Assessment of Potential Economic Bene-fitsUsually, there are two separate and distinct

aspects of this matter. One is the relative costof acquiring data by satellites as compared withother means. The other is the economic benefitto the user of the processed data. For example,it will cost more to collect, analyze and distrib-ute worldwide meteorological data using satel-lites than it now costs to collect meteorologicaldata on 10 to 20 percent of the Earth's surface.However, the economic benefit to the consumerderived from longer range weather forecastsma.de possible by availability of worldwide datamay outweigh by far the relatively minimaladditional cost of data collection, analysis, anddistribution.Benefits should not be construed too nar-

rowly; in some cases, it will cost more to collectdata using satellites than is now being spent onnonsatellite means. However, the benefit to theconsumer may far outweigh the greater cost tothe user.In the Earth resources area, enormous eco-

nomic benefits may be realized when it becomesfeasible to survey the Earth's natural and cul-tural resources from space. While the cost tothe user--the surveyor--may be considerable,the use of spacecraft to survey Earth resourcesshould become more economical with time, asthe survey (sensory) capability of individualspacecraft and systems grows beyond a singledisciplinary area.In some areas, the Summer Study Group may

have to make its own assessment of benefits, be-cause such information has not yet been devel-oped.Wherever possible, potential economic bene-

fits should be "quantized" to demonstrate spe-cific economic advantages of the satelliteapproach.4. Assessment of Other ImplicationsThis section considers political, social, and

other aspects of space applications, both proand con.The benefits which have resulted from com-

munications and meteorological satellites in theform of improved communications and under-standing and in timely warnings of weather

259-790---_7_2


10/138

A SURVEYFSPACE APPLICATIONSphenomena are well known. Even so, the fullpotential of meteorological and communica-tions satellites is still unrealized as the follow-ing sections of this prospectus will attest.The benefits which can be realized from theremote sensing of the Earth's natural and cul-tural resources are expected to be substantialespecially for developing countries. The ex-ploding world population creates an urgent re-quirement for better methods to uncover theEarth's resources. Only through a current andcomplete inventory of the Earth's full resourcescan improved and more efficient resources man-agement be applied. To realize such benefits,it will also be necessary to resolve complex prob-lems of territorial access, international use ofsurvey data, etc.Broadcast satellites can open new vistas for

mass information and education, but broadcastsatellites will raise new problems of assuringinternational order, if their emissions are notconfined to national boundaries.5. BackgroundThis section deals with the previous activity

which is the basis of our current program andof our predictions for the future. In someareas, there is an extensive background of spaceexperiments and space-oriented research. Thisis particularly true in the area of communica-tions and meteorology, where space flight pro-grams date back 5 years or more. In otherareas, the background is less specific; however,visual and infrared pictures acquired in themeteorological and manned space flight pro-grams have already provided valuable inputs toour study of the Earth resources survey pro-gram, and pictures from high altitude aircrafthave provided valuable correlation with pie-tures from space.6. NASA PlansThis section outlines not only the current,approved NASA program in each area, but also

outlines the future possibilities for applicationsas we see them, based on currently availableevidence. The summer study will assess thesepossibilities, and others, from all standpoints,and provide guidance on the most promisingavenues for future work. NASA's currentand l)lanned l)rogr.tms consist of advanced re-

search on new materials, processes, and tech-niques applicable to space activities, anddevelopment of sensors and spacecraft to dem-onstrate technology usable in one or severalspecific applications. Research activities arenot necessarily applications oriented; precisespacecraft stabilization is equally use:ful whetherthe spacecraft is looking outward at space orinward at the Earth.7. Contributing Studies and ActivitiesThis section complements sections 5 and 6,

by presenting current and planned activitiesknown to be underway outside of NASA, bothdomestic and foreign, which are considered rele-vant to the study. It includes the related activ-ities of other V.S. Government agencies suchas the FAA, ESSA, U.S. Geological Survey,and Director of Telecommunications Manage-ment; known activities of private industry andacademic or nonprofit organizations; andapplicatiolrs-oriented programs in foreigncountries.8. Suggested Additional StudiesThis section indicates those elements of infor-

mation which will probably not be available asa result of current or previous efforts by NASAor others, so that those who will participate inthe study may take steps beforehand to fill thesegaps in the input.9. BibliographyThis includes not only technical references,

but references dealing with economic, political,social, and legal aspects of space applications.In addition to Ol)en literature items, it refers tointern./1, unpublished material not available forgeneral distril)ution.There is some redundancy and repetition in

these discussions due mainly to the common-ality of sensors and of spacecraft to more thanone al)plicatiolL For example, the Applica-tions Technology Satellites discussed in Chal)-ter l I: "Colnnnlnications," will also (.arry me-teorological and navigation experiments; andfuture Applications Teclmology Satellites areintended to I)e even more versatile experimen(splatforms. Sensors developed initi'dly for me-teorology are already finding application in theEalcch resources ai_a. In fact, an iml)o_ant


11/138

INTRODUCTION 5objective of NASA's space applications effortis to provide multipurpose sensors and space-craft. Translated to operational systems, thiswill spread costs over a larger area of applica-tions per system, and reduce the cost to a par-ticular user.In assessing opportunities and techniques,one should keep constantly in mind an extreme-ly important problem faced in both experi-mental and operational systems--that of com-municating and processing raw data and dis-seminating processed results. Should the sen-sor collect and transmit data continuously orselectively ? What format should be used tofacilitate automatic processing? Will the vol-ume of communications overload available fa-

cilities? Are frequencies allocated or allo-cable for the type of service envisioned? Dif-ferent applications will have different require-ments. Meteorol%o T requires several synopticpictures each day, while some Earth resourcesapplications may have renewal rates of days,weeks, or months. The equipment, manpower,and dollar costs for timely collection and con-version of sensory data into useful informa-tion, and distribution of the information, areessential elements of the overall evaluation.The discussions do not include considerationDf possible military utilization of the tech-nology, or of the data from particular appli-cations. This is because (1) unique militaryrequirements are being met with unique mili-tary systems, and (2) "common" requirementsare furnished by DOD to the cognizant non-military Government agency (e.g., FAA,ESSA) and incorporated into their overall sys-tem requirements._Vhile the utility of man in space is discussedin the individual sections, it should be notedthat man's role is still being assessed very de-liberately and is subject to further findingsconcerning man's capability for prolonged workin the space environment.Man may play a vital role in some applica-tions, either by augmenting programed scan-ning with information from manually operatedsensors concerning areas or features of particu-lar interest, or by providing information--suchas sea-state information--which may prove verydifficult to obtain with remote unmanned sen-

sors. On the other hand, data transmissioncapability from manned spacecraft to groundmay be quite limited, especially the capabilityto physically return records to earth. This pro-vides additional impetus for selective observa-tions as opposed to continuous recording.Policy Considerations.--In the bTationalAeronautics and Space Act of 1958, Congressdeclares that it is the policy of the United States"that activities in space should be devoted topeaceful purposes for the benefit of allmankind."Satellites are by their very nature interna-tional, and NASA has made agreements withmany foreign countries for participation inNASA experimental programs for communica-tions, meteorology, tracking, geodesy, etc. Acomplete catalog of NASA international agree-

ments is contained in (9). Examples includethe U.S.-U.S.S.R. bilateral cooperation in com-munications and meteorology (8), contributionsto the plans of the _Vorld Meteorological Orga-nization (WMO) for an advanced internationalmeteorological program (world weather watch)(4), and the agreements under which a dozencountries constructed earth stations to partici-pate in testing experimental communicationssatellites (9).In the applications area, the United Stateshas now joined in a cooperative venture withmany other nations (the international telecom-munications satellite consortium--Intelsat) tobuild a global communications network (6).Our TIROS cloud pictures have been madeavailable on a real-time basis to any countrywilling to make a small investment in groundreadout equipment. Potential users are inves-tigating a common satellite navigation system,while the question of educational TV satellitesystems is being widely debated.Space technology now promises help in tack-ling an even greater task--the gathering ofinformation about the Earth resources that manmust be able to find and use if lie is to livedecently on this planet as its population grows.But while the potential uses of these newtechnologies generated by the space programexcite the imagination and promise direct eco-nomic and social benefits to mankind, theynonetheless carry important policy implications.


12/138

6 A SURVEY OF SPACE APPLICATIONSRelationship Between R. & D., Exploita-

tion, and End Use.--Extending the range ofapplications of satellite technology necessarilyposes new problems for the relationship betweenresearch, exploitation, and the role of the enduser. Institutional arrangements will vary ineach particular case, depending upon whetherthe function (1) can be developed as a com-mercial enterprise such as communications;(2) is a public service like weather informationor aids to navigation; or (3) involves the col-lection and dissemination of commercially val-uable information as in the case of agriculture,oceanography, or geology. For example, theevolution of the institutional arrangements forexploiting communications satellite technologyillustrates the complex relationships existingbetween the initial R. & D. effort (NASA), theexploiting function (Comsat), and the end user(common carriers and the public).In the ease of the TIROS weather satellites,the requirements justified establishing a special-ized system so that a single agency (ESSA),as the primary end user, could assume completeoperation and control. Under such circum-stances, the interagency relationships are rela-tively simple and have administrative proce-dures evolving along with the technology.This pattern might not hold with future systemsand particularly with the Earth resources sys-tems which concurrently se_we a number ofagencies and end users by means of multipur-pose sensors.NASA's role h'ls been to develop space tech-nology for actual or potential space applica-tions (and this may in some instances necessi-tate postulating requirements in order that theteclmology can be advanced on a broad front).Exploitation of space technology and developedcalmbilities has chiefly been the responsibilityof user agencies, governmental and private. Aspart of this exploitation, the user agencies haveusually assumed the function of operating theapplications satellite systems. It can be notedthat NASA, through the operation of itsmanned and unmanned missions undertaken toadvance space science and technology, has de-veloped great experience in and facilities foroperational control of satellite systems. Thisoperational capability is a beneficial adjunct to

other users--for example, NASA supports theCommunications Satellite Corp. with tracking,communications, and computing services duringthe initial phases of new Comsat missions.NASA launches TIROS operational satellitesand makes comprehensive tests in orbit beforeturning the satellites over to the EnvironmentalScience Services Administration (ESSA), andif an operating satellite malfunctions, controlreverts to NASA for engineering analysis.Thus, there is a close and continuing interplaybetween development, demonstration, test, andoperation.Sensitivity of Findings.--When the identityof the ultimate user of satellite-supplied infor-mation becomes more apparent, and when it be-comes more apparent how that information isintended to be used, a whole range of politicaland economic questions may arise that will callfor further investigation in depth. For ex-ample, neither the Department of Agriculturenor the Geological Survey would necessarily bethe only end users of information gathered intheir respective fields; they may use this d_ttain pursuit of their missions and in developingnational policy, but they would also dissemi-nate certain information of commercial valueon crops and resources. Such information couldhave significant economic, political, .md eveninternatiomtl implications. Consequently, con-sideration needs to be given to the manner ofrelease to assure public access on an equitablebasis as well as respecting privacy rights.International Faetors.--The internationalarrangements made by NASA in connectionwith experimental programs, and the interna-tional aspects of initial applications programsin communications and meteorology, have al-ready been mentioned. Details on these ar-rangements will be found in the cited references.Other international activities which might bereviewed in preparation for the Study are: (a)the NASA/French agreement for ProjectEOLE, an experimental data-gathering satelliteto operate in conjunction with balloons, (b) theIndian Ocean and Inter-American experimentalmeteorological sounding rocket programs--with their implications for future global net-works, and (c) other foreign national interestsand capabilities in meteorological soundings.


13/138

INTRODUCTION

On the communications side, the status ofINTELSAT, current planning for global andregional service, the necessity to review theInterim Agreement in 1969, and the problemsand progress of ground terminal installationsin developing areas, should be taken intoconsideration.The actions of the U.N. Committee on thePeaceful Uses of Outer Space and of the Inter-national Civil Aviation Organization in the

area of navigation and air traffic control satel-lites should be reviewed. The current statusand interest of international organization forgeodetic satellite observation would be pertinentas well.With special relevance to the broad problemsof developing international earth resources sur-veys, particular attention should be given to

initial arrangements for international partici-pation in airborne tests of remote sensors. Con-crete examples of international interest in thefirst early products of earth photography in theGemini program should also be noted (SouthAfrica, Peru, Sudan_ etc.).Interest has been stimulated on the part ofdeveloped countries in the NASA technologyutilization program, particularly in France_Belgium, and Euratom, and a policy has beenformulated to govern the release of the pro-gram's products abroad and, at the same time_to promote the establishment of similar pro-grams overseas. In developing countries, suchas India, Pakistan_ and Brazil_ there is specificinterest in the possible use of satellite technologTfor practical national applications. Paren-thetically, the ELDO program and the FrenchGuiana range both hold special interest forpractical applications launchings.

Considerations for Future InternationalActivity.--(a) It will be important :to preservea careful distinction between the experimentalperiod and any operational-commercial periodin designing future programs since the types ofarrangements which are possible and appro-priate may differ very significantly in the twoperiods.(b) The fact that remote sensing and earthresources surveys from satellites have not yetbeen demonstrated on a significant scale shoulddictate great caution in establishing interna-

tional contacts or in stimulating foreign expec-tations of benefit.(c) Careful consideration must continue tobe given to foreign participation and data shar-ing in earth sensing programs. The implica-tions of conduct, participation, and sharing

must be distinguished as they may relate respec-tively to hardware, raw data, digested results,and the analysis process itself. This problemis discussed further in a subsequent section onlegal factors.(d) Given the considerations noted in (b)

and (c) above, a certain degree of foreign par-ticipation in early experimental work appearsto be desirable in attesting to the bona tides ofthe program and U.S. motivations.(e) Where there is any prospect of a com-mercial character in future practical applica-tions, careful thought should be given to thepositive and negative experience which has beenhad in organizing international participation incommercial satellite communications.(f) Consideration needs to be given to therights and obligations of the United States with

respect to the collection, analysis_ dissemination,and use of data relating to foreign resources ofcommercial value or potential. These rightsand obligations may differ as between data ofcommercial interest in foreign national terri-tory, on the high seas or in Antarctica, or inouter space. The cost, locus, and staffing of theanalysis process will all be of concern to othernations as well as to the United States.(g) Consideration of satellites for broad-casting--to community or home receivers as dis-tinguished from use of satellites for networkprogram distribution--involves availability offrequencies and broadcasting across interna-tional boundaries. These problems may exertconsiderable influence on the technology re-quired, such as highly directive antennas toconfine illumination to one country or subcon-tinent.(h) International and national plans andpolicies concerning frequency utilization forspace applications will be a factor in all appli-cations areas. Allocations made by the Inter-national Telecommunications Union in 1963

(2) are largely shared with similar terrestrialservices. Sharing requires limitations (on


14/138

8radiatedpower,requencyassignment,luxden-sity,antennaointing)whichinhibit thegrowthof both thespaceandterrestrial servicesn-volved. TheSummerStudyGroupshouldbe-comefamiliar with theprincipalReportsandRecommendationsf the InternationalRadioConsultativeCommitteen thisarea(atitsXIthPlenaryAssembly,Oslo,1966)(3), andwithrelevantdomesticstudiessuchas thoseper-*..... _ by o.... _ ........... ", , byOLllltt_t_. kJLD_IIAUI.'U /_ttDt2_tI'(31l JLll_tlbUbt5 aIl_Jansky and Bailey for the Director of Tele-communications Management (1, 5).Legal Factors--Since the start of the spaceage, a legal regime governing activities in outerspace has been taking shape. The legal prin-ciples have emerged in several ways. Certainprinciples have been established by tile actionand inaction of space and nonspace powers,thus taking the form of customary interna-tional law. A wide international consensus onbasic principles has found expression in resolu-tions of the General Assembly of the UnitedKations. Finally, the Test Ban Treaty and thetreaty governing the exploration and use ofouter space (7), including the Moon and othercelestial bodies, signed January 26, 1967, by theSecretary of State, place a number of importantobligations and limitations upon signatory na-tions engaged in space activities as well as con-ferring significant rights upon parties to thetreaties.The emerging legal regime for outer spaceactivities is, of course, superimposed upon theuniversally accepted regime of national sover-eignty over the land, the continental shelf, theterritorial seas, and the air space. However,where national sovereignty prevails, a nationcan largely control information-gathering with-in its borders and thus guard one of the mosthighly prized of its resources--its privacy.The principles of law that are emerging in re-spect to activities in outer space, which pro-

claim freedom to explore and use outer spaceand deny such concepts as national appropria-tion and sovereignty in outer space, in com-bination with the potential of satellites forearth-oriented data collection, give rise tochallenging questions relating to this prizedresource of privacy.Among the questions posed are the follow-ing: Are there any limits placed by internation-

A SURVEY OF SPACE APPLICATIONSal law upon earth-oriented data collection fromouter space ? What legal obligations are placedupon a nation gathering data to share that in-formation with other nations? Does any suchobligation depend upon where the data is ob-tained-from the sovereign territory of anotherstate rather than from the high seas, for ex-ample ? Can information obtained by satellitebe exploited in some fashion to the detriment ofthe state yielding up the information ?It is clear that a consensus on the foregoingquestions has not been reached; in fact, theyhave not been the subject of much formal dis-cussion in international forums. One of themost important statements by the UnitedStates relevant to these issues was made bySenator Gore on December 2, 1962, as a mem-ber of the U.S. delegation to the United Na-tions, when he offered the view that observationfrom outer space is as consistent with interna-tional law as is observation from the high seas."With malice toward none, science has decreedthat we are to live in an increasingly open world,like it or not, and openness, in the view of(the United States) Government, can onlyserve the cause of peace."It seems likely that the development of a con-sensus regarding information-gathering fromouter space will not follow the relatively easycourse of earlier principles of law governingactivities in outer space. It may well be easierto reach a consensus on international arrange-ments covering the conduct of such activitiesthan upon the basic rights and obligations thatexist as a matter of law.Equally complex legal issues are posed inconnection with the use of communications

satellites, particularly with regard to directbroadcast. Similarly, the uses to which knowl-edge regarding weather may be put in the formof weather modification and control pose im-portant legal questions. The framework withinwhich these questions will be resolved is as yetnot clear.To preclude any misunderstanding concern-ing the intent of the summer study, this intro-duction will conclude with the observation that

the inquiry should not be considered as an effortto justify the application of space _chniquesto functions or services now performed with


15/138

INTRODUCTION 9terrestrial means. The proposition for usingspace teclmiques must withstand a critical an-

alysis of the relative priority of a need, ,theease of meeting it, and the cost of meeting it.

Bibliography(1) Atlantic Research Corp. (Jansky & Bailey Divi-

sion), "Space Service Spectrum Saturation," var-ious reports on a study for the Director of Tele-communications Management.(2) International Telecommunications Union, "FinalActs of the Extraordinary Administrative RadioConference to Allocate Frequency Bands forSpace Radiocommunication Purposes," Geneva,1963.

(3) Internat iona l Telecommunications Union, Inter-national Radio Consultative Committee, "llthPlenary Assembly of the CCIR, Oslo, June-July1966, documentation to be available by June 1967.

(_) Interagency Committee for International Mete-orological programs, "Proposed U.S. Participationin an International Meteorological Program,"report, January 10, 1966.(5) Stanford Research Institute, "International Tele-communications Policies, Technology and Eco-

nomics," study for the Director of Telecom-munications.

(6) U.S. Department of State, "CommunicationsSatellite Corporation (COMSAT)--AgreementBetween the United States of America and OtherGovernments, and Special Agreement Concludedby Certain Governments and Entities Designatedby governments," treaties and other interna-tional acts, series 5646.

(7) U.S. Department of State, treaty governing theexploration and use of outer space.

(8) U.S. House of Representatives, Committee onScience and Astronautics, staff study on futurenational space objectives, July 1966.

(9) U.S. Senate, "Texts of Executive Agreements,Memoranda of Understanding, and Other Inter-national Arrangements, 1959-65," staff report,Committee on Aeronautical and Space Sciences--U.S. International Space programs.

(10) Ibid., p. 409.


16/138

II. COMMUNICATIONSIntroduction

Satellites are already an important adjunctto other means for common carrier communica-tions. As the capability and versatility of satel-lites increase, we can foresee their applicationto a much broader field of communications. Inthis chapter, we consider the application ofspace techniques in five other areas. These are:

Point-to-point systems providing com-munications among many small inexpensivetransportable and fixed terminals havingsimultaneous aceessibility to the satellite.Broadcast satellites. This includes notonly the function of network program dis-tribution, but also satellites broadcastingdirectly to communities (educational orotherwise) for limited local distribution,and eventually for broadcasting directly toindividual home radio or television re-ceivers.Satellites to relay communications be-

tween the Earth and lunar planetary anddeep space missions.Satellite communications systems tocollect information from remote data gath-

ering stations (oceanographic, meteorolog-ical, hydrological, etc.), and relay thisinformation to centers for processing andanalysis.Satellites in earth orbit to relay dataand/or voice communications from other

mission spacecraft to mission control cen-ters, thus providing greater continuity ofcommunication and control.

In each of these areas, technological advanceswill enhance the technical feasibility of the pro-posed service and influence the cost effective-ness. The more important advances consideredin this chapter include:

Large structures erectable in space, forlarge antennas, large solar power arrays,and solar concentrators.

Sources of prime power having greatercapacity than solar cell power supplies.More precise spacecraft attitude control

and station keeping techniques.Better understanding of propagation

through the ionosphere and atmosphere.Better definition of the Earth's noise en-vironment.Apparatus to exploit the use of milli-

meter, submillimeter and optical wavelengths.Generation of high power RF energy in

space.Small Terminal Multiple Access

CommunicationsAs used here the area includes, the conveying,

by satellites relay, of intelligence (aural, visual,data, signal, or record traffic) from point-to-point on the Earth's surface between ever in-creasing numbers of small, inexpensive mobileand fixed terminals having simultaneous or mul-tiple accessibility to the satellite. Communica-tion with aircraft, ships, balloons, buoys, etc. iscovered in other sections.1. Status and Prospects of Existing Methods

HF and VHF radio relays, UHF tropo-spheric scatter links and submarine cables arethe principal ground based communicationssystems utilized for long distance point-to-pointcommunications today. HF radio, while stillin use, is not a dependable service because it issubject to the vagaries of the ionosphere andin locations where more than one reflection isinvolved, the multipath effect sometimes causessevere fading of the received signal. VItFradio is limited to line of sight distances, andis therefore unsuited for long distance com-munications. The state of the art in UHFtropospheric scatter systems has advanced sig-nificantly in recent years. A chain of UHFscatter links over a northern route does provide

11


17/138

12 A SURVEY OF SPACE APPLICATIONSchannels across the Atlantic Ocean but the qual-ity is dubious, the available bandwidth is lim-ited, and the cost is great. Moreover, suchlinks would not serve for some transoceanicroutes due to excessive distance between poten-tial station sites.While submarine cables currently in use are

distinctly limited in bandwidth to 128 voicechannels, cables utilizing advanced solid staterepe_.ter technology h:ve been d_velopad.These cables are reportedly capable of televi-sion bandwidths or 800 or more voice channels.A.T. & T. made application to tile Federal Com-munications Commission recently to connectJacksonville, Fla. with the Virgin Islands usingthis kind of cable. Of the various existingcomnmnications methods, these advanced cablesoffer the best prospects for high capacity point-to-point communications. For short haul, highdeusity routes, such cables could probably com-pete with all other communications services.For longer distances, they may well run intoeconomic or technical restrictions. It is notedthat cables can only serve users having accessto fixed cable terminations, thereby limitingpotential user accessibility. Cables are alsolimited in accommodating changing trafficpatterns.

All of these facilities except HF radio areconstrained by their economics to service be-tween points having relatively large traffic re-quirements. HF radio can provide telegraphand limited telephone service almost, withoutgeographic restriction, but the telephone serv-ice in particular is substandard in quality andcontinuity due to ionospheric effects.2. Possible Space Applications

The capability for providing high qualitycommunications links for transmitting voice,television and data traffic between a few large,sophisticated, and expensive earth terminals bysatellites has been developed, demonstrated, andreduced to commercial operational practice.Refinement and utilization of that capability isbeintz carried out by the Communications Satel-lite Corp. and its foreign counterparts inIntelsat.While existing terrestrial and satellite com-

nmnications methods fail to provide satisfac-tory solutions to the small terminal multiple

access communications problem, the applica-tion of space technology is considered to havethe greatest potential for solution to thisproblem.

a. A satellite, because of its high altitude, willpermit coverage of very large areas, thus ena-bling the establishment of communication linksbetween widely separated users. If the syn-chronous orbit is used, the area of coverage pos-_ihla i_ nanrlv harni_nharla. Nearlv completeearth coverage is possible with only three equallyspaced geostationary satellites.b. The communications links between earthterminals and satellites are inherently reliablebecause the propagation of electromagneticwaves in the region of the frequency spectrumallocated to space communications is not ad-versely affected by anomalies of the ionospherenor does it limit wideband transmissions.Faraday rotatioll is not a problem and cosmicnoise contributions are minimal at thesefrequencies.

c. If the satellite is truly geostationary, atracking capability is not required, thus per-mitting the use of low cost, fixed antenna in-stallations on the ground.

d. Satellites can be designed for a number ofmultiple access modulation teclmiques. Iftime division multiplex (TDM) techniques areused, the user will receive all of the radiatedpower from the satellite. TDM seems to havethe highest potential for communications be-tween small and mixed size terminals.

e. If passive reflector communications satel-lites are utilized, the bandwidth available isalmost unlimited because it is a linear device;it can be used simultaneously in many ways, atmany frequencies, and at different power levelswithout crosstalk. Terminal configurations,capacities and modulation/multiplexing tech-niques can be changed at will.

f. In the future, satellite systems will berequired to accommodate an ever-increasingnumber of smaller and smaller terminals of re-duced cost. This can be provided by eitherincreasing the power handling capabilities ofthe satellite or by being able to direct energyback to the users with increased precision, orboth. Rapid progress is being made in bothareas under NASA and the Communications


18/138

COMMUNICATIONS

Satellite Corp.'s flight programs. Furtheradvances might be constrained more by inter-national regulations concerning frequencysharing than by technological limitations.3. Assessment of Potential Economic BenefitAssessments of the potential economic bene-

fits of point-to-point satellite communicationshave been made by many authors. Less atten-tion has been given to date to satellite com-munications economics for small users than inthe case of large users of major communicationroutes. In the latter instance, the space seg-ment costs are small when compared to the costof a few sophisticated, large earth terminalssuch as the Andover and Pleumeur Bodou facil-ities. For small terminal multiple access com-munications via satellite, the cost of the groundsegment is spread among many small terminals,and the cost of the space segment is likely tobe as much as an order of magnitude greaterthan Intelstat II. The potential economicbenefit to be derived is dependent on the numberof small users, an unknown entity. A con-certed economic assessment of the benefits isdiscussed later on in section 8, as a candidatefor additional study.4. Assessment of Other Implications

a. Existing communications satellites andthose planned by the Communications SatelliteCorp. within this decade are not expected tosatisfy the needs of all small users. Someunderdeveloped areas of the world may not beserved by the commercial global satellite system(unless they have terrestrial connections to aregional Earth station); and, it appears un-likely that all the underdeveloped areas of theworld will be able to use the commercial system.

b. Exploitation of this application of spacecould result in important political and socio-logical benefits, demonstrate the vigor of thesp_e effort on behalf of those unable to partic-ipate in the commercial system, and promotethe prestige of the United States in the under-developed areas of the world.Large-scale access would also alleviateanother problem, that of providing long dis-tance terrestrial trunks for distribution of traf-fic to and from a few large regional earthterminals. In many cases these trunks are in-

13adequate or nonexistent. (Obviously sometrunk facilities are necessary in any case toprovide access to any Earth station from beyondits immediate vicinity.)

e. It must be noted that large-scale multipleaccess may also create new problems of its own.Widespread access to the spacecraft repeaterwill upset long-established patterns for central-ized control and routing of communicationstraffic; and may present problems in determin-ing and charging for use of the system on anequitable basis. Access by many small termi-nals may result in less efficient use of the fre-quency spectrum. This depends, of course, onthe methods of modulation and RF multiplex-ing employed.d. Small terminal multiple access communi-cations techniques and methodology could con-

tribute to those aspects of navigation, trafficcontrol, air-sea emergency rescue operations(see ch. VI) which involve the transmission ofintelligence to and from small terminals, such asships, aircraft, and emergency craft.5. Backgrounda. Historlzal Development to Global SystemThe need for communications satellites de-veloped as a result of increasing world require-ments for long-distance, real-time communica-tions. In 1945, Arthur C. Clarke proposed arelay station in orbit as an artificial earth satel-lite; however, this solution aroused little inter-est and lay dormant for more than a decade.By 1955, many technical solutions to the needfor long-distance communications had been ex-ploited, but all represented compromise of someform and most were limited by their very ter-restrial nature. Clearly, the communicationsatellite was a better method, and in 1959 theNational Aeronautics and Space Administra-tion initiated a program to develop the necessarytechnology.Echo I, a passive reflector balloon, waslaunched August 12, 1960. This satellite hasbeen called one of the best ambassadors theUnited States ever had inasmuch as it has beenclearly visible to millions of people throughoutthe world.Between July 1962 and August 1964, NASA'sprogram resulted in the successful launches of


19/138

14two A.T.&T. Telstars (July 10, 1962 and May7, 1963), two relays (December 13, 1962 andJanuary 21, 1964), another Echo (January 25,1964), and three Syncoms (February 14, 1963,July 26, 1963, and August 19, 1964).Relay I provided the first satellite communi-cations link between North and South America.

With a history of 81 TV demonstrations, Re-lay I has operated through more than twice itsdesigned lifetime, it ceased operations inFebruary 1965.Syncom II, also operating beyond its design

life, has made outstanding contributions to theknowledge of gravitational anomalies. Syn-corn II has recorded more satellite communica-tions, "ON" time than all other communicationssatellites combined. It continues to functionafter over 2 years in orbit.Relay II has successfully conducted many TV

demonstrations and communications experi-ments, and continues to function satisfactorilyin orbit.Syncom III was the first satellite to be suc-

cessfully boosted, attitude controlled, injected,and maneuvered into a preselected station ingeostationary orbit, requiring most preciseorbital control to accomplish.Demonstrations have shown the feasibility

and value of a communications satellite in gee-stationary orbit to provide multichannel voicecommunications, multichannel teletype, andTV, with and without simultaneous voice.

Syncoin III successfully relayed the Olym-pics from Japan to the United States in Octo-ber, 1964. Both Syncom's were turned over tothe Department of Defense for operation onApril 1, 1965.With regard to the status of foreign partici-

pation in communication satellite activities,since 1961 foreign governments have been par-ticipating in the NASA experimental communi-cations satellite program. Bilateral agree-ments have been made between NASA andBrazil, Canada, France, Federal Republic ofGermany, India, Italy, Japan, Scandinavia,Spain, the United Kingdom, and the Union ofSoviet Socialist Republics. (The first phaseof cooperative U.S.-U.S.S.R. experiments incommunications satellites was executed in 1964using Echo II). Fifty-four nations are now

A SURVEY OF SPACE APPLICATIONS

signatories to an Agreement * * * '_* * * toestablish a single global commercial communi-cations satellite system as part of an improvedglobal communications network. * * *" Eachsignatory has designated a communications en-tity to actually participate in the system. ThisConsortium of communications entities isknown as Intelsat. The U.S. member of theConsortium is the Communications Satellite

WIIICII O.XSb_blOllI$110._Al lit U_LA)-t_orp. ( tJomsa_), wasber 1963 pursuant to the Communications Satel-lite Act of August 1962. Comsat is also man-ager for Intelsat of the space segment of theglobal system.It is U.S. policy to support the single

global commercial system concept. Under theconcept of a single global system for commer-cial use, it will probably become desirable to em-ploy a number of different types of satellites be-cause there are unique requirements for domes-tic and/or regional usages which are not easilyaccommodated with a single satellite type. TheU.S.S.R. has already established an experi-mental-operational system using Molniya Isatellites for intra-Soviet communications, andthere have been discussions of international useof this system. (The Soviets have reportedthat Molniya I because of its high powerand directive antennas, makes use of smallerearth terminals than is possible wi_h IT.S.satellites.) Serious consideration is beinggiven in the United States to domestic systemsfor TV program distribution, air traffic control,and other uses. France has proposed an experi-mental system for communications betweenFrance, Africa, and South America. Severalother countries are known to be considering useof satellites for domestic communications aswell as for "external" traffic.b. Multiple Access lrmpllcat_on._ and CCIR/

I T U Regulation ConstraintsAt the present stage of development, com-

munications satellites are power limited; thatis, the ratio of RF bandwidth to base b.aadwidthmust be large to realize high quality trafficchannels in spite of the low power output capa-bility of satellites.In 1963, a total of 2,800 Mc/s was allocated by

the International Telecommunications Union(ITU) for communications satellite use pri-


20/138

COM_IUNICATIONS 15marily in bands already allocated for terrestrialpoint-to-point radio relay services. Suchshared allocations were based on extensivestudies by the ITU members, from whichevolved specific conditions under which suchsharing could succeed.The principal criterion for sharing is that theflux density at the earth's surface shall not ex-

ceed -159+ (s_/15)dbw/m2/4 KHz (s_ beingthe elevation angle of the satellite above thehorizon).The introduction of new communications

satellite services, at different frequencies, suchas air traffic control services at VHF, and pos-sibly TV program distribution services at fre-quencies other than those now allocated forso-called point-to-point services, may requiredevelopment of a new set of sharing criteriasuited to the particular characteristics of thesystems involved.As noted above, today's power-limited satel-

lites employ frequency modulation with a largemodulation index, so that RF bandwidth isseveral times greater than the baseband width.As the demand for satellite communications in-creases, so will the RF bandwidth requirement.One can foresee the time when present alloca-tions become inadequate. There is a require-ment, therefore, to make better utilization ofavailable frequencies.One avenue is increased ERP from the satel-lite-allowing reduction of modulation index.This avenue ends when the flux density limit isreached.Another is reuse of the same frequencies.With the narrow beams characteristic of 40- to

85-foot earth station antennas, the same fre-quencies can probably be used for different satel-lites separated by 4 degrees or more as seen fromthe Earth. However, the trend is to increasesatellite ERP to permit reducing the cost andcomplexity of Earth stations. This will resultin smaller antennas with wider beams, raisingthe angular separation between satellites neces-sary to reuse the same frequency.Still another way to improve frequency utili-

zation is to design repeaters to pass only a por-tion of the allocated band. Other satelliteslocated in the same vicinity (within 4 degrees asseen from the Earth) could employ nonoverlap-

ping frequency coverage. This allows greaterflexibility in "repeating" the use of the samefrequencies.Another approach is the use of modulation

techniques--such as pulse code modulation(PCM)---having a greater tolerance for co- andadjacent-channel interference than widebandFDM/FM.The subject of frequency utilization is an ex-

tremely complex one, involving tradeoffs amongmany factors, not all of which are technical.The factors which must be considered includethe probable distribution of earth stations; therequired location(s) of satellites to serve thesestations; the degree of multiple acce_ that isfeasible to serve the requirements; the trafficvolume and its variability in time and routing;and the extent to which communications bysatellites will be applied to services other than"common carrier" communications.6. NASA Plansa. Objectives of the Current Progranv To insure that the technology required inthe nationM interest for the establishment of

future small terminal multiple access commu-nications satellite systems is developed. To study the requirements for, and tech-

nically assess the applicability of satellites tothe future needs of small terminal multipleaccess communications systems. To fulfill NASA's responsibilities underthe Communications Satellite Act of 1962. To flight test communications technologyfor the geostationary orbit which is common to

a number of small user applications. To conduct communications experiments on

the Applications Technology Satellite series oflaunches.The last two objectives are the principal com-

munications objectives of the current Applica-tions Technology Satellite (ATS) program,discussed in the next sect ion.

(1) Applications Technoloyy Satellites.--Aspart of its program to develop and test spacetechnology for satellite communications, NASAplans to flight test various concepts of space-craft stabilization and orientation techniques,high gain phased array antenna of large size,and other communication techniques, includingmillimeter and laser technology.


21/138

16 A SURVEY OF SPACE A_PLICATIONSATS flights in 1966 and 1967 will test tech-

niques for directing antenna beams from spin-stabilized spacecraft in geostationary orbit.ATS flights in 1967 will yield design data andcriteria for gravity gradient stabilization at lowaltitudes, and in 1968 for synchronous altitudes.The principal characteristics of the communica-tions related experiments on the ATS aresummarized as: Communications service quality consistentwith International Radio Consultative Com-

mittee (CCIR) recommendations. Dual-mode transponders-frequency-trans-

lation mode, 25 MHz bandwidth; SSB/PMmode for multiple access, 5 MHz bandwidth. 6,000 nautical-mile, three-axis gravity

gradient experiment; launched April 5, 1967. Synchronous-equatorial, spin-stabilized

spacecraft; ATS-I, launched December 1966,and ATS-C, to be launched in late 1967, withelectronically despun phased array antenna(ATS-I), mechanically despun antenna (ATS-C), and VHF spacecraft to aircraft communi-cations experiment (both). Synchronous-equatoriM, three-axis gravity

gradient stabilized spacecraft; launch readi-ness: ATS-D (mid 1968), ATS-E (late 1968). Ground terminals at Moj'tve and transport-

able station at Toowoomba; 40-foot parabolawith Cassegrainian feed; 5.6 MtIz SSB trans-mitter (1,o-00 channels) ; 240 channel multiplexreceiving equipment. Primary ground terminal(Rosman II) at Asheville, N.C., 85-foot parab-ola with Cassegraini'tn feed; 5.6 MHz SSBtransmitter (1,200 channels); 1,200-channelmultiplex receiving equipment. Communications experiment-multichannel

one-way telephony; multichannel telephone-multistation loading ; high speed data transmis-sion; color TV; VHF experiment; millimeterwave propagation experiment (16 and 35 Gttz).

(2) Passive Satellites.--A study is underwaywhich will compare cost-effectiveness of activeand passive communications satellites for vari-ous applications considering recent advances inmodulation teclmique_% si_ml processing meth-ods, availability of large boostel% and new mate-rials, erection systems, and structural concepts.

(3) Frequency Utilization.--One solution tothe problem of sharing frequencies with other

services is to employ frequencies above 10 GHzfor satellite communications, as exclusive allo-cations in this range may be possible. ATS-Ewill include a multimeter-wave propagation ex-periment, as noted above, to explore the utilityof these higher frequencies. NASA is also in-vestigating the matter of experiments to pro-vide additional data on the feasibility of shar-ing between proposed domestic communicationssatellite systems and terrestrial radio relay sys-tems in the 4 and 6 GHz bands. This work is be-ing done at the request of the Director of Tele-communications Management, Executive Officeof the President.b. Future PossibilitiesA follow-on Applications TechnologT Satel-

lite (ATS-F/G) program to the present ATSA-E series of launches is planned. Broadlystated the ATS-F/G objectives are to developtechnology commonly required for several spaceapplications and to provide for early flight testof experiments representing promising ad-vanced concepts for several different space ap-plications. The effort is specifically directedtoward the geostationary orbit, which has manyadvantages for space applications.Specific technical objectives of ATS-F/G

are: Large (30 foot) space-erectable parabolicantenna with surface good to 10 GHz Accurate (0.1 ) long-lived, three-axisstabilization

Antenna steering capability (across wholeEarth in one-half hour) High gain (3040 db) multibeam antenna Precision radio interferometer Other experiments requiring precise sta-bilizationAmong other things, these techniques wouldcontribute to the capability for communications

among a number of small Earth terminals ona multiple-access basis.ATS flights in 1970 and 1971 will test activethree-axis stabilization in a synchronous

equatorial orbit to 0.1 and to increase the or-bital lifetime of such systems to at least 2 years.A 30-foot or larger diameter parabolic antennawill be on board and will be deployed after thesatellite is placed in synchronous orbit.


22/138

.d

COMMUNICATIONS

The high-gain, multibeam steerable phasedarray antenna, currently being developed,would contribute to small terminal communi-cations and their accessibility to satellites; thelarge parabola would also contribute by pro-viding high gain for spacecraft-to-groundcommunications and a large receiving aperturefor low-power ground transmitting.NASA plans to utilize the technologies and

teclmiques under consideration to demonstratethe capability for small terminal communica-tions on a multiple-access basis to detelaninethe optimum combinations for providingservices to users.7. Associated Studies and Activitiesa. A d Hoe Intragover_mental U ommwnicatio_s

Satellite Policy Coordination Committee(OTM)The committee is examining policy questions

relating to Government procurement of com- (1)munications services, utilization of satellites fordomestic services, U.S. leadership in communi-cations satellite technology exploitation and use,Government funding of supporting researchand technology contributing to communications (2)satellite development, and adequacy of pro-grams in research and development to meet na-tional objectives. The Director of Telecom-munications Management is conducting a study (s)of frequency requirements through 1980_ andthe results should be available in time for the (4)study.

(1) The Communications Satellite Corp. hasconducted and is still conducting studies on both (5)frequency division and time division multiplex(TDM) techniques for multiple access. A suc-cessful demonstration of a TDM system was (6)conducted in July 1966 through Intelsat I.Also, Comsat has studied the application of (7)communications satellites to domestic common-carrier service, and other domestic and inter-national services. (s)(5) The Federal Communications Commis-

sion has conducted several inquiries applicableto these matters :--Notice of inquiry (Docket No. 16058),

June 16, 1965, authorized entities and au- (9)thorized users under the Communications (10)Satellite Act of 1962.

17--Notice of inquiry (Docket No. 16495),March 2, 1966, on establishment of domes-tic noncommon carrier communication sat-ellite facilities by nongovernmental en-tities.

--Notice of inquiry (FCC Docket No. 16979),November 10, 1966, regulatory and policyproblems presented by the interdependenceof computer and communications servicesand facilities.

8. Suggested Additional StudiesA comparison and tradeoff study of socio-

economic and political benefits and problemareas would be useful to the planning for smallterminal multiple-access communications sys-tems of the future. Studies of this kind shouldbe updated periodically and refined because bytheir very nature they defy precision.Bibliography

Aein, M. M., "Multiple Access Capability of aHard-Limiting Communications Satellite Re-pea,ter With Spread-Spectrum Signals," Insti-titute for Defense Analyses, Washington, D.C.,April 1964, 43 pp.Bedrosian, E., Feldman, N., Northrop, E., Soil-frey, W., "Multiple Access Techniques for Com-munication Sa telli tes--Survey of the Problem,"Rand Corp., Santa Monica, Calif., September 1964,134 pp.Bell Telephone Laboratories, "Special Issue onTelstar I," Bell System Technical Journal, vol.XLII, July 1963, No. 4, pts. 1, 2, 3.Bell Telephone Laboratories, "Special Issue onProject Echo," Bell System Technical Journal,vol. XL, July 1961, No. 4."Communications Satellites," a Continuing Bib-liography, NASA Office of Scientific and TechnicalInformation. NASA SP-7004. Covers the period1957 to January 1966."DOD-NASA Review of Communications Satel-lite Technology," J. R. Burke and J. Kaiser, Sep-tember 1963, IDA/Hq 63-1870.Enloe, L. H., "Decreasing the Threshold in FM byFrequency Feedback," Proceedings of the Insti-tute of Radio Engineers, January 1962.Erhardt, H. R., et al., "The Advanced SyncomCommunication Antenna System--A DirectiveArray for a Spin-Stabilized Satellite," HughesAircraft Co., Culver City, Calif., In IEEE NewLinks to New Worlds, 1963 National Space Elec-tron. Symp. 1963, 33 pp.Final Report on the Relay I Program," NASASpecial Publica,tion SP-76, GPO 1965.Gay, A. C., and Greenberg, T. S., "The Potentialsof High-Power Satellites for Communications,"


23/138

18 A SURVEY OF SPACE APPLICATIONSRadio Corporation of America, Princeton, N.J.,Systems Engineering and Space Tech., 1964, pp.40-43.

(11) Greenbert, J. S., Gubin, S., and Handelman, M.,"Overseas Commercial Communications SatelliteSystems," Radio Corporation of America.

(12) International Radio Consultative Committee(CCIR) : Documents of the XIth Plenary Assem-bly, Oslo, 1966 (particularly the documents ofStudy Group IV, Space Systems and Radio-astronomy).

(13) Jaffe, L., Smith, T. A., and Attaway, L. D., "TheImpact of Communications Satellites on the Less-Developed Areas, Science, Technology, andDevelopment." U.S. papers prepared for theUnited Nations Conference on the Application ofScience and Technology for the Benefit of theLess Developed Areas, vol. XII, GPO, January1963.

(14) Lutz, S. G., "Multiple Access Satellite Communi-cation," Hughes Research Labs., Malibu, Calif.,Final Report, Aug. 20, 1962-Aug. 20, 196:5. 74pp. Refs NASw-495.

(15) Mueller, George E., "Satellites for Area Com-munications," Space Technology Labs., Inc., Re-dondo Beach, Calif., Astronautics and AerospaceEngineering, vol. 1, March 1963, pp. 66-69.

(16) NASA Techni_.,ql Report TR R-233, "SyncomEngineering Report," Syncoln Proj. Office, God-dard Space Flight Center, vol. 1, March 1966.

(17) Nichols, R. T., "Submarine Telephone Cables andInternational Telecommunications," The RandCorp., RM-3487-RC, February 1963.

(18) Reiger, S. H., "A Study of Passive Communica-tion Satellites," Rand Corp., Santa Monies, C'llif.,N-63-13030, February 1963.

(19) Reiger, S. H., Nichols, R. T., Early, L. B., andDews, E., "Communications Satellites: Technol-ogy, Economics and System Choiccs," The RandCorp., February 1963, RM--34S7-RC.

(20) Schwartz, M. L., and Goldson, J. M., "ForeignParticilmtion in Communi(.ations Satellite Sys-tems: Implications of the Communications Satel-lite Act of 1962," The Rand Corp., February 19(;3,RM 3484-RC.

(21) "Spacecraft Antenml Systems," Finql Engineer-ing Report, Hughes Aircraft Co., NAS5-3545, Oc-tober l_363-January 1966.

(22) "Syncom II and III Evaluation Report," U.S.Army Satellite Communication Agency, Nov. 30,1_4.

(23) "VHF Air('raft Satellite Relay," Final Report ofFlight Test, Bendix Radio Div., Bendix Corp.,April 1965.

Broadcast SatellitesTo 'rid in discussing this space al)plication , itis (lc_iral)h_ to define communications satellites

devoted to the service of delivering "broadcast"

programing material in terms of direct broad-cast, community broadcast and distributionsatellites. The direct broadcast satellite ampli-fies and retransmits the standard TV signal forreception by individual home radio or televisionreceivers of the conventional variety. (Thistype of reception could imply the use of a spe-cial antenna and preamplifier, but these wouldbe of modest cost.) Satellites from which pro-gram material is received by more elaborate re-ceiving equipment than the currently availablehome receivers are called community broadcastsatellites. To complete the definitions, satellitesfrom which program material is received bycomplex earth terminals, and delivered to theconsmner via wire or rebroadcast by conven-tional local broadcast stations--are called d;_'-tribution satellites. Community broadcastingand distribution sa.tellites might use nonconven-tional nmdulation techniques.1. Status and Prospects of Existing MethodsTelevision is discussed first because it is what

most people think about. Until quite recent-ly, the television sign.tl that came into the homewas carried on an electromagnetic wave radiatedfrom a local television station's transmittingantenna. With the passage of time, many iso-lated trod remote communities are now beingserved by community antenna (CA'FV) systems.Direct transmission of instructional, educa-tional programs to schools and univeluities, overa five-state area in the midwest, is being carriedout by Midwest Program Airborne Television,Inc. (MPATI) using a high flying aircraft.Since the major sources of television program-

ing material originate in a few cities, mainlyNew York City and Los Angeles, a vast sys-tem of broadcast networks has evolved over thepast twenty years. The means for distributingcommercial program material to affiliated net-work stations are achieved primarily by micro-wave relay and land cables. To satisfy theneeds of those localities (beyond the range ofTV broadcasting) stations, CATV systems havemoved into communities large enough to sup-port the required investment. There are morethan 1,800 CATV installations in operationwithin the coterminus United States, whichutilize sufficiently elaborate antennas to pickup weak signals from remote and shielded


24/138

COMMUNICATIONS 19broadcast stations and feed signals into homesof the communities served using coaxial cables.The sources of educational program materialare much more limited in number than com-

mercial television and only seven of the 115 orso educational television (ETV) stations areregularly interconnected. Program material isput on video tape and mailed to the ETV sta-tions. Facilities do not exist, as yet, to putcolor programs on video tape for distribution.Further, nearly all ETV stations would have tobe modified to handle color programs.In the United States, the technology and

existing methodology for monochrome and colortelevision broadcasting is mature; for all prac-tical purposes the central problem is one ofcost. Microwave relay over subcontinentMdistances is limited to approximately thirty milehops, and they are costly and must be servicedand maintained. Television bandwidth landcables are widely used, but they are costly andlimited by the number of channels which can bepassed.Inasmuch as cost is the central problem in

television program distribution in the UnitedStates, other solutions, such as satellites, arebeing considered by the networks and ETV be-cause the cost may be less when satellites areused than with microwave relays and landcables.The annoyance of "ghosting," particularly in

large cities, due to signal reflections from tallbuildings, is an important transmission defici-ency. The quality of color reception is degradedeveu more than monochrome television becauseof smearing due to multipath. A solution to thisproblem is transmission via wires, and the custo-mer will be expected to pay for the service asin the case of CATV.Outside the United States, construc.tion of

microwave relays and/or land cables over un-favorable terrain and a general lack of an ade-quate technology base pose very formidableproblems, particularly in the underdevelopedareas of the world, notwithstanding the eco-nomic aspects.In the related field of radio broadcast, radio

program material is transmitted on three fre-quency bands: HF (560 to 1760 KHz), short-

wave ( 3 to 30 MHz) and VHF (87.5 to 108MHz).For aural transmissions in the HF shortwavebands the dynamic fading effects which showup as a distinct flutter of the voice program ma-teriM is characteristic of long distance transmis-sion. Such dependence on transmission byreflection from the ionosphere causes "DeadSpots" (so-called skip distances) and preventsreception in many areas. Because of the va-garies of the ionosphere transmission paths areuseful for only certain periods during a day.All these effects when combined with contiml-ally increasing frequency assignment require-ments result in a mammoth frequency manage-ment problem and unsatisfactory reliabili.ty.For aural transmission of frequency modula-

tion programs, in the VHF band, presently usedtransmission systems are limited in geographicaldistribution, have undesirable effects in fringeareas, with weak signals, and are subject tomultipath effects in both urban and fringe areas.The introduction of FM-multiplex for stereotransmission requires an even stronger signaland is also more susceptible to multipath effectsfrom both stationary and moving reflectors.2. Possible Space Applications

a. A satellite, because of its high altitude willpermit coverage of very large areas, thus ena-bling the establishment of a television programdistribution system capable of serving bothcommercial and noncommercial (ETV) broad-cast outlets of subcontinents, such as the UnitedStates. This particular application is con-sidered distribution communications and withinstate of the art.In fact, much attention is being given to this

subject in the United States, and four proposalshave been made to the Federal CommunicationsCommission (in response to FCC Notice of In-quiry, Docket No. 16495, referred to in the pre-ceding section) for establishment of domesticcommunications satellite systems. The Ameri-can Broadcasting Co. and the Ford Foundationproposed systems exclusively for TV programdistribution, while the systems proposed byA.T. & T. and the Communications SatelliteCorp. would handle both TV program materialand common carrier communications. In Jan-uary 1967, the Carnegie Commissions recom-


25/138

20mended a large-scale program for educationalTV, including the use of comnmnication satel-lites as appropriate. The most recent impetusto the program was President Johnson's mes-sage to Congress on February 9_8,1967, concern-ing health and education in which he recom-mended creation of a Corporation for PublicTelevision. The President said that one of theCorporation's first tasks should be to study thepracticality and the economi_ .qdvantages ofusing communication satellites to establish aneducational television and radio network.

b. Most probably the earliest capability foreffective space TV broadcasting would be basedupou the community broadcast satellite ap-proach. A community broadcast satellite, ingeostationary orbit, offers the potential for dis-semination of instructional television directlyto educational facilities and communities. Theuse of a satellite for this purpose appears to bea natural followon to the MPATI programusing aircraft. A more elaborate receivingsystem would be required, but the area of cov-erage could be extended from 5 States to 48States. For example, if one would pernfit thedesign of a new receiver, making use of fre-quency modulation techniques instead of ampli-tude modulation techniques, and permit theuse of a special outdoor antenna connected tothe receiver--then the following could be done. Spacecraft weight and size could be main-tained within the limits of proven launchvehicle combinations.

Spacecraft components and subsystems re-quired for community broadcasting couldmake use of technology which is eitherflight proven or in an advanced state ofdevelopment. The development time required for estab-lishing an operational capability could beas much as one-half that needed for directbroadcast satellites.The teelmology for such a joint space-groundsystem is within reach within this decade. Forexaml)le , one spacecraft design concept wouldbe basically an outgrowth of NASA's currentA1)plication Technology Satellites (ATS)which utilizes an expanded cylindrical solarcell array to increase available solar power withmiuimal weight increase. Either an eleetroni-

A SURVEY OF SPACE APPLICATIONScally despun phased array antenna or a mechan-ically despun parabolic derived reflectorantenna could be utilized to direct the radiatedenergy to the desired geographic areas.

c. For underdeveloped countries, the instal-lation of a nationwide communication systemcapable of transmitting television program ma-terial by use of radio relay and coaxial cablescould take more than a decade. A possiblesolution is the installation of a distribution sat-ellite to effect this TV distribution. This satel-lite would have a visual channel and severalassociated voice channels. These voice chan-nels could be in several languages or dialectswhen associated with the TV program materialor could carry independent radio program ma-terial. Such a system need not be limited to asmall geographical area, and in fact could betailored to many different geographical areas ofalmost any desired size and eonfigalration.An alternative solution is the communitybroadcast satellite. Such satellites could beeffectively used to disseminate television pro-gram to educational and community facilitiesover subeontinental areas. A space capabilitycould be realized in the early 1970 time period,if it is desired.

d. A direct bro'td('ast TV satellite, in geo-stationary orbit, offers the potential for provid-ing a new dimension in mass information dis-pensing to entire populations. By its very na-ture, a single geostationary satellite could servegeographical areas of one to 3 million squaremiles; and quality of reception improved overterrestrial broadcasting because signal degrada-tion factors such as reflection, terrain absorptionand nmn-made noise might be greatly reducedbecause of the high angle of arrival and uni-formity of sigmal strength potentially possiblewith a geostationary satellite. The high arrivalangle of signals from the satellite should alsoreduce nmltipath effects and ghosting, a primesource of picture degradation or smearing incolor reception, and permit satisfactory recep-tion in mountain areas where conventional cov-erage is spotty or poor. Antennas used withhome TV receivers, and at earth terminals usedto transmit program material to the satellitecould be fixed, thus reducing the cost and com-plexity associated with tracking antenna sys-tems.


26/138

C01_EVIUNICATIONS

The satellite system will have to be technicallycompatible with contemporary receivers in itsarea of coverage : that is, it will have to employthe same standards as terrestrial transmitters,so that the viewer needs only a single receiver.Where more than one political subdivision is tobe served, the satellite design will be more com-plicated if television standards of the subdivi-sion are different.There are no frequency allocations, as yet, forsatellite broadcasting services. Because of the

high signal strength required, it may not befeasible to share frequencies now assi_md toterrestrial communications services. Exclusiveallocations may be difficult to obtain at fre-quencies where competition is intense.A direct broadcast TV satellite will have to

radiate a great deal of power so that the signalsit retransmits will be strong enough to be pickedup by conventional home TV receivers. Suchsatellites would require primary power sourcesconsiderably beyond the 35-kilowatt capabilitiesof even the nuclear-turbealternator of theSNAP-8 class, the largest for which technologyis under development, unless the conventionalTV receiver is equipped with a directive antennaaugmented possibly by a preamplifier. In suchan approach, the onboard satellite power re-quirement could be reduced to about 20 kw. Nosuch power sources now exist, but there is workunderway on nuclear and even solar power sys-tems at this level. The direct broadcast TVsatellite would also require the development ofa large-space erectable antenna that could beaccurately pointed at a particular geographicalarea. Some preliminary work is now underwayon space erectable antennas. If the necessarypower source and antenna development pro-grams are vigorously pursued, this kind of satel-lite capability might be possible in the mid-1970's. Techniques must also be developed forgenerating the requisite RF power, cooling thehigh power components, and efficient meansfound for dissipating the heat losses in thesecomponents. The Apollo Applications pro-gram may provide the requisite capability forplacing such heavy payloads in orbit, whethermanned or unmanned.

e. Direct broadc_t radio satellites capable oftransmitting aural program material to conven-

21tional FM and/or shortwave radios could beused to overcome the deficiencies in existingmethodology. Shortwave transmission from abroadcast satellite located over the desired geo-graphical area such that its transmissions willpenetrate the ionosphere would provide a signalwithout as much fading and flutter effects..Frequency modulation broadcasting of multi-channel voice programs could be likewise dis-tributed over much larger geographical areasthan at present, eliminating the so-called fringeareas that surround metropolitan areas andproviding a signal free of multipath and there-fore more suitable for FM-multiplex transmis-sion of stereophonic programs.Radio broadcast satellites are beyond the state

of the art because he gain of the spacecraftand ground-receiving antennas must be limitedto manageable dimensions. Hence, the space-craft transmitter power must be of the orderof a few kilowatts if the transmitted signals areto be strong enough to be received by conven-tional radios. If desired, a space capabilitycould be demonstrated in the early 1970's.3. Assessment of Potential Economic BenefitAssessments of potential economic benefits of

broadcast satellites have been made by a numberof investigators. The most recent and mostpublicized assessments were submitted to theFederal Communications Commission by theFord Foundation and others in response to theCommission's Notice of Inquiry of March 2,1966, in the matter of the "establishment of do-mestic noncommon carrier communications-sat-ellite facilities by nongovernmental entities,"Docket No. 16495. The Commission's inquirywas initiated as a result of an application bythe American Broadcasting Co. to own and op-erate a communications satellite for networkdistribution of television program materials toits affiliated stations. The Ford Foundation in-dicated that the toll receipts from audio andvisual transmissions during 1965 were $65 mil-lion. While ABC's figures were somewhatlower, both entities estimated that substantialannual savings could result from the use of com-munications satellites for network distribution.(A detailed discussion of these proposals, and


27/138

22 A SURVEY OF SPACE APPLICATIONSthe related question of subsidizing distributionof ETV program material, is beyond the scopeof this doctunent. The proposals have beenquoted extensively in the press, and will prob-ably be the subject of hearings before the Sub-committee on Communications of the SenateCommerce Committee.)The Radio Corp. of America compl

Date post:	08-Apr-2018
Category:	Documents
Upload:	bob-andrepont
View:	218 times
Download:	0 times