magsat press kit

8/8/2019 Magsat Press Kit

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lulsrNewsNational Aeronautics andSpace AdministrationWashington, D.C 20546AC 202 755-8370

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For Release TUESDAY,October 23, 1979

Press Kit Project MagsatRELEASE NC,: 79-129

October 19, 1979


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RELEASE NO: 79-129

CONTENTS

GENERAL RELEASE................................. 1-8MISSION DESCRIPTION................................ 9-10THE SPACECRAFT .......................... 10-16DATA COLLECTION AND PRCCESSING .................. 16-17MAGSAT INVESTIGATIONS PROGRAM ................... 18-20LAUNCH VEHICLE.................................. 21-25LAUNCH TO ORBIT PHASE .......................... 26MAGSAT ORBIT PARAMETERS ........................ 27SEQUENCE OF INITIAL FLIGHT EVENTS ............... 27-28POST LAUNCH SEQUENCE ........................... 28-29MAGSAT GROUND TRACK FOR FIRST 24 HOURS .......... 30MISSION MANAGEMENT TEAM ......................... 31-32CONTRACTORS ............................. 32

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National Aeronautics andSpace AdministrationWashington, D.C. 20546AC 202 755-8370

For Release:Dick McCoriack DCTUESDAY,eadquarters, Washington, D.C. Otbr2,17(Phone: 202/755-4321) October 23, 1979Jim LacyGoddard Sparse Flight Center, Greenbelt, Md.(Phone: 301/344-5565)

RELEASE NO: 79-129SATELLITE TOSTUDY EARTH'S MAGNETIC FIELD

The first spacecraft specifically designed to measurethe near-Earth magnetic field and crustal anomalies isscheduled to be launched no earlier than Oct. 2.

Called the Magnetic Field Satellite (Magsat), this NASAexperimental spacecraft will be placed in a sunlit (dawn todusk) Sun-synchronous, nearly polar orbit with a perigee of350 kilometers (215 miles) and an apogee of 500 km (345 mi.).This low orbit will provide for successive spacecraft

Earth tracks approximately 150 km (92 mi.) apart coveringthe globe completely every 1.0 days.

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The planned minimum mission life of 120 days is ex-pected to yield at least three complete sets of global mag-netic field data which will permit averaging and statisticalanalysis. The launch, by a NASA Scout launch vehicle, willbe from the Air Force Western Space and Missile Center,Lompoc, Calif.

In addition to a scalar magnetometer to measure themagnitude of the Earth's crustal magnetic field, Magsat willbe the first spacecraft in near-Earth orbit to carry a vec-tor magnetometer which will measure magnetic field directionas well as magnitude.

Scientists hope that Magsat data will reflect importantgeologic features such as composition, temperature of rockformation, remanent magnetism, and geologic structure (fault-ing, subsidence, etc.) on a regional scale. Such knowledgewill help in the understanding of large-scale variations inthe geologic and geophysical characteristics of the Earth'scrust and, in turn, aid in the planning of minerals exploration.

Scientists from the United States and eight foreigncountries -- Australia, Brazil, Canada, France, India, Italy,Japan and the United Kingdom -- will carry on 32 investigationsin six general categories: geophysics, geology, field model-1 nr, rarLne studies, magnetosphere/ionosphere and core/mantle studies.

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Magsat's main mission objectives are to:a Obtain an accurate, up-to-date quantitative descrip-

tion of the Earth's magnetic field;

* Provide data and a worldwide magnetic-field modelsuitable for U.S. Geological Survey update andrefinement of world and regional magnetic charts;

* Compile a global two-dimensional (scalar and vector)crustal magnetic anomaly map. The spatial resolutiongoal of the anomaly map is to be better than 350 km(219 mi.).

The principal user of Magsat data, the Geological Surveyof the Department of the Interior, has cooperated closelywith NASA in setting mission objectives and will participatein the data analysis. Magsat data will be used by the Geo-logical Survey in its publication of updated magnetic fieldcharts and maps in 1980 for navigation and geological use.

Prior to the satellite era, magnetic data from manygeographic regions were acquired over periods of years througha variety of measurement techniques. Data on many regions,such as oceanic and polar, was either sparse or nonexistent.

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Satellite measurements of the gaomagnetic field beganwith the launch of Sputnik-3 in May 1958, and have continuedsporadically in the intervening years. To date, only thethree Polar Orbiting Geophysical Observatories and the Orbit-ing Geophysical Observatories 2, 4 and 6 have provided anaccurate global geomagnetic survey. These satellites operatedbetween October 1965 and June 1971, and provided global mea-surements of the field magnitude over an altitude range of400 to 1,500 km (205 to 930 mi.).

These satellite geomagnetic field measurements weredesigned to map the main geopotential field originating inthe Earth's core, to determine the long-term temporal orsecular variations in that field, and to investigate short-term field perturbations due to ionospheric currents. Earlyin the polar orbiting observatory era, it was thought to beimpossible to map crustal anomalies from space. However,whLle analyzing data from these satellites, it was discoveredthat the lower altitude data contains separable fields dueto anomalies in the Earth's crust, thus opening the door toa new class of investigations.

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-6-Magsat data is expected to be superior to the polar

orbiting observatory data in two areas:e Vector measurements will be used to determine the

directional characteristics of anomaly regions and to re-solve ambiguities in their interpretation. Knowledge of thevector components will permit identification of field varia-tions perpendicular to the main field,and thereby restrictthe range of possible models which can explain the anomaly.The vertical component will provide more precise informationon the boundaries of the anomalous region.

* Lower altitude data will provide increased signalstrength and resolution for detailed studies of crustalanomalies. Signal strength and resolution increase rapidlywith decreasing altitude. The magnitude of the anomalousfield should increase nearly fivefold at 300 km (187 mi.),and the finer resolution possible will allow more detailedgeological interpretations of anomalous regions.

Magsat data will be correlated with other geophysical mea-surements and with geological information to produce regionalcrustal models. For example, the highly accurate determina-tion of the Earth's gravity field using laser tracking ofsatellites and satellite altimeters provides information aboutthe densiLy distribution within the Earth's crust.

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-7-Magsat is the third in a series of low-cost, modular

design satellites, designated Applications Explorer Missions,built to be placed in special orbits to satisfy mission-unique experimental data acquisition requirements. Manyof the component systems for Magsat make use of space hard-ware left over from the Small Astronomy Satellite which waslaunched in 1975. Cost of the Magsat program is $19.7 million.The spacecraft is made up of two parts: (1) the instru-ment module with the optical bench, star cameras, altitudetransfer system, magnetometer boom and gimbal systems, scalarand vector magnetometers and precision Sun sensor; and (2)thebase module which houses the electrical power supply, tele-metry, altitude control and command data handling systems.

Overall spacecraft weight is 181 kilograms (399 pounds).Its solar panels provide 160 watts of power. A three axiscontrol of + 5 degrees enables the satellite to maintainattitude so that the magnetometer, Sun sensors, star camerasand the solar panels are properly oriented.

NASA's Goddard Space Flight Center, Greenbelt, Md., isresponsible for the design, integration and testing of thesatellite and data processing.

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-8-Magsat data will be stored on two onboard tape recorders

and transmitted when the satellite is within reception rangeof the following NASA receiving stations: Merritt Island,Fla.; Goldstone, Calif.; Fairbanks, Alaska; Orroral, Australia;Madrid, Spain; Goddard; Kauai, Hawaii; Quito, Ecuador;Santiago, Chile; Guam; and Ascension Island.

The spacecraft's base and instrument modules were builtby the Applied Physics Laboratory, Johns Hopkins University,Laurel, Md.

NASA's Langley Research Center, Hampton, Va., managesthe four-stage, solid-fuel Scout-G launch vehicle whichwill place Magsat in orbit. Scout is built by the VoughtCorp., Dallas, Texas.

The Magsat mission is a project of NASA's Office ofSpace and Terrestrial Applications.

The launch wLidow is 9:09 a.m. to 9:15 a.m. EST, Oct. 29.

(END OF GENERAL RELEASE. BACKGROUND INFORMATION FOLLOWS.)

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MISSION DESCRIPTION

The third Applications Explorer Mission, the MagneticField Satellite (Magsat) is scheduled to be launched fromthe Air Force Western Space and Missile Center on board aScout-G solid-fuel launch vehicle no earlier than Oct. 29,1979. The launch window is 9:09 a.m. to 9:15 a.m. EST.Although the minimal lifetime is four months, current pre-dictions, based on p-cesent solar activity, imply a lifetimeof nearly six months before reentry will occur.Magsat instruments consist of a scalar and a vectormagnetometer. The scalar instrument is a dual lamp cesiumvapor magnetometer. The vector instrument is a three-axisfluxgate magnetometer. When uncertainties associated withorbit position, spacecraft attitude and attitude transferbetween the sensor platform and the spacecraft are takeninto account, the expected accuracy for the scalar measure-ment is +3 gamma in total field and for the vector measure-ment +6 gamma in each component. The spacecraft will belaunched into a 350 by 550-km (215 by 345-mi.) Sun-synchro-nous orbit with an inclination of 97 degrees. The scien-tific measurements will be stored on tape recorders andtelemetered to a receiving station approximately once everyfour orbits. The base module Magsat uses is residual hard-ware from the Small Astronomy Satellite.There were 32 investigations selected in response toan Announcement of Opportunity issued Sept. 1, 1978. Theyincluded 13 foreign investigations from Australia, Brazil,Canada, France, India, Italy, Japan and the United Kingdom.The six general categories of research are geophysics,geology, field modelling, marine studies, magnetosphere/ionosphere, and core/mantle studies. Data distributionwill be through the National Space Science Data Center.Goddard Space Flight Center is responsible for overallproject management, data acquisition and operation of theatellite, as well as instrument development, data process-ing and management of the investigations program. TheApplied Physics Laboratory of Johns Hopkins University ishe prime spacecraft contractor.Successive spacecraft Earth tracks will be approximately150 km (93 mi.) apart and will provide complete global cover-age in about 10 days. However, due to magnetic disturbancescaused by solar activity, 50 days will be required to gathernough good data. The planned minimum mission life of 120days is expected to yield at loast three complete sets ofglobal data which will permit averaging and statistical analysis.

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Upon orbit injection, Magsat will deploy its solararray and turn 90 degrees to face the solar cells towardthe Sun. The solar array will furnish 160 watts to powerthe spacecraft. The spacecraft will be oriented with itsaxis pointing towards Earth. A pitch momentum wheel andhorizon scanner will maintain this attitude as Magsattravels around the Earth. The 6-meter- (20-foot)-longmagnetometer boom will then be deployed aft and the mag-netometers will be energized and magnetic measurements willcommence. Star cameras mounted to the optical bench willbe used to determine the spacecraft's attitude to within+10 arc seconds. An attitude transfer system will measurethe pitch, yaw and roll angles between the vector magneto-meter and the star cameras within +10 arc seconds. Adirect reading precision Sun sensor mounted near the vectormagnetometer will provide redundant roll angles to within+10 arc seconds.

Data will be recorded on an 8.9 x 107 bit Odetics taperecorder at 2,000 bits per second (2 kilobits per second).Every third or fourth orbit the tape recorder will be readout (dumped) at 320 kbs. Real-time data at 2 kbs may betransmitted by the spacecraft along with the tape recorderdump. Data will be provided to the Geological Survey foruse in their models, charts and mapsand to the scientificcommunity for appropriate investigations.Program costs related to Magsat, excluding the launch

vehicle and tracking and data network operations total$19.7 million.

THE SPACECRAFT

The spacecraft is made up of two modules: the base modulewhich houses the electrical power supply system, the tele-metry system, the attitude control system and the commandand data handling system; and the instrument module whichcomprises the optical bench, star cameras, attitude transfersystem, magnetometer boom and gimbal systems, scalar andvector magnetometers and precision Sun sensor.

The base module structure is the Small Astronomy Satel-lite design and incorporates its salient features, i.e.,central column, eight trusses, thermal control louvers, for-ward and aft honeycomb decks and hinged solar array.

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-12-Instrumient Module

The instrument module structure is bolted to the baseodule and consists of four truss structures, a base plate,he optical bench and the boom drive and gimbal assemblyousing. Listed below are the pertinent parameters of thepacecraft.Height: 164 centimeters (63 inches)874 cm (344 in.) with trim boom extendedDiameter: 77 cm (30 in.), solar panels and magneto-meter boom extendedWidth: 340 cm (134 in.), tip to tip, solar arraydeployedLength: 722 cm (284 in.), length along flight path -magnetometer boom and solararray deployedWeight: Base Module - 115 kg (254 lb.)Instrument Module - 66 kg (145 lb.)Total - 181 kg (399 lb.)Power: 160 wattsAttitude Control: Three-axis stabilization (momentumwheel and magnetic torquing)Command and Data Handling: S-band transponder -2282.5 MHzDoppler Beacon: 162 and 324 MHz

The primary subsystems in the instrument module include:e A 6-m (20-ft.) extendable boom and a sensor platformith vector and scalar magnetometers, and a precision Sunensor.* An optical bench with two star cameras and threettitude transfer systems components.o Associated electronics.

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Scalar MagnetometerThe scalar magnetometer measures total field magnitude.The magnetometer is a cesium (Cs 133) vapor, self-oscillat-ing, four gas-cell, dual lamp magnetometer with active thermalcontrol. It consists of an electronics pazkage, a sensorassembly and a redundant radio frequency exciter package.The sensor assembly, mounted on the sensor platform, will beextended from the satellite body by a 6-m (20-ft.) scissorsboom to minimize magnetic interference from the satellite.The radio frequency exciter and electronics packages arelocated in the instrument module.The cesium vapor magnetometer uses optical pumping toproduce an interaction of the magnetic moment and the angularmomentum of the valence electrons of the cesium with theambient magnetic field to cause an oscillation whose fre-quency (Larmor frequency) is directly proportional to theamplitude of the magnetic field. The frequency is 3.499 Hz/


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Notes: 1. 5.8 meters (228 Inches) + Before magnelorrteer.boomdeployment.Aerodynamic2. For clarity, thermal trim aurfa 7.1 meterslankets are not shown. NSDSAD (Seonote1)

Base modul

q; E I~~~nstrument ie~gzmoe1.64 mete rsFlIght (64.5 Inches)

Drc -6.02 meters (237 Inches)

MAGSAT Orbital Configuration, Top ViewSensor platform PrecisionSensor AT S dihedral Vector Su nplatform mirror magnetometer sensor

magnetometerBoom sections -t Boom Boom drive(stowed) nmen

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The output signal of +8 volts corresponding to a nag-netic field of +2,000 gamma will be digitized using a 12bit A/D converter providing resolution of 0.5 gamma. Theoffset bias generator produces 128 automatically controlledbias steps of 1,000 gammas each to extend the range to+64,000 gammas.The magnetometer draws approximately 1.8 watts fromthe unregulated bus to power the electronics. The redundantpower converters are synchronized to the main satellite con-verter and will free-run if the svnchronizinq sianal is lost.

Sensor BoomThe magnetometer boom must separate the sensor platformfrom the source of strong magnetic fields in the instrumentand base modules by a distance of 6 m (20 ft.). It mustalso maintain the position of the sensor platform such thatits angular deviation relative to the attitude transfer sys-tem optical axis never (or rarely) exceeds 3 arc minutesover a reasonable portion of the spacecraft's useful life-time. Finally, the magnetometer boom must keep the centerof the plane mirror that is attached to the vector magneto-meter mounting plate confined to a square area that measures3.81 cm (1.5 in.) on a side and whose geometric center co-incides with the attitude transfer system optical axis.The 6-m (20-ft.) boom consists of seven pairs of links.The individual links are rectangular tubes of graphite epoxy5.08 by 1.02 cm (2 by .4 in.) with walls 0.08 (.03 in.) thick.Inner and outer surfaces are protected from moisture absorp-tion by aluminum foil 0.018 millimeter (.0007 in.) thick.The magnetometer sensor and Sun sensor are connected to theinstrument and base modules by an electrical cable thatpasses through the boom links. This cable consists of 128conductors and weighs 2.72 kg (6 lb.).Firing pyrotechnic devices release sensor platformcaging and boom link caging. Preloaded springs cause theboom to extend about 0.6 m (2 ft.). An alternating currenthysteresis synchronous motor drives the ends of the root-links together and with the springs produces full extensionof the boom. Power to the drive motor is automatically cutoff by a limit switch at full extension.

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The graphite fiber/epoxy boom link material was chosenfor light weight and minimum coefficient of thermal expan-sion. An average coefficient of approximately +0.32 x 10-6cm/cm/degrees C over a temperature range of -12 degrees to43 degrees C (54 to 109 degrees F.) has been achieved forthese links. The outside of the links is covered with alumi-nized Kapton film with an aluminum oxide overcoat to providethe proper solar absorptivity and emissivity to minimizetemperature gradients and provide an operating temperaturein full Sun of 25 degrees C (77 degrees F.).To eliminate built-in mechanical misalignments (thatmight go undetected during ground testing) and initial thermalbending, the boom is provided with a ground-controlled three-axis gimbal. This gimbal is located at the boom base and,upon command from the ground, tilts the boom in either pitchor yaw or rotates it in twist as necessary. It is capable of+2 degrees adjustment in pitch and yaw and +5 degrees in twist.The boom waighs 6.781 cg (15 lb.) and the gimbal weighs2.984 kg (6.57 lb.).

DATA COLLECTION AND PROCESSING

Data will be recorded on an 8.9 x 107 bit Odetics taperecorder at 2,000 bits per second (2 kbs). Every third orfourth orbit the tape recorder will be read out (dumped) at320 kbs.Techniques developed and proven effective for scalarmagnetometer data from the Polar Orbiting Geophysical Obser-vatory satellites will be refined and utilized for Magsat.This includes extensive checking of the quality of the dataprior to release for analysis. For scalar data, the goalis to have the data ready for analysis two to three monthsafter acquisition. Insofar as possible, the scalar datawill be utilized to verify and calibrate the vector data.'ne success of this procedure depends upon the achievedaccuracy of the scalar instrument, the noise levels in thetwo instruments, and the stability of the fluxgate magneto-meter over a period of a few hours. It is anticipated thatsuch in-flight calibration will be possible to a 2-3 gammalevel of accuracy in eaih component.Vector data will first be processed and available inthe magnetometer coordinate system. Any calibration of thevector instrument by the scalar instrument will be appliedat this stage.

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Transformation of the vector data to an Earth-orientedsystem requires knowledge of the attitude of the magneto-eter relative to the spacecraft and knowledge of the atti-ude of the spacecraft. These attitude determinations wille accomplished in two stages. First, overall attitude wille determined to about 20 arc-minutes. These results wille available four to six weeks after acquisition of the data.he final definitive attitude determination will require morextensive analysis and will not be availab.le until aboutight months after acquisition of data.Because of the time necessary to accomplish the defini-ive attitude determination, vector data in an Earth-orientedsystem will be available for analysis in two stages, corres-onding to the two stages of attitude determination. Pro-essed data will be available at 20 arc-minute accuracy aboutwo or three months after acquisition of data and at 20 arc-econd accuracy about eignt months after data acquisition.For users who require an up-to-date spherical harmonicodel of the Earth's field, an initial model for the epoch ofhe measurements will be generated as soon as possible. Suchmodel could be available as early as two months after launch.t will not include secular variation. More definitive modelsill be developed after a substantial amount of data is acquirednd the 20 arc-second attitude determination is accomplished.Present plans call for release of the data to theational Space Science Data Center at Goddard as soon ast is ready for analysis. This data will be provided tohe public at a nominal cost.

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MAGSAT INVESTIGATIONS PROGRAM

Following a NASA Announcement of Opportunity on Sept. 1,1978, a number of investigators were selected to conduct ex-periments using the Magsat data. The selected investigators:both U.S. and foreign, represent government agencies, univer-siti s and industry, as indicated in the following list.GeophysicsR. L. Coles Reduction, Verification andGeomagnetic Service Interpretation of Magsatof Canada Data Over Canada

B. N. Bhargava Magnetic anomaly and MagneticIndian Institute Field Map Over Indiaof Geomagnetism

W. J. Hinze Processing and InterpretationPurdue University of Magnetic Anomaly DataOver South America

G. R. Keller Synthesis of Data forUniversity of Texas, Crustal Modeling of SouthEl Paso America

P. Gasparini Crustal Structures Under theUniversity of Naples Active Volcanic Areas of theItaly MediterraneanN. Fukushima Regional Field Charts, LocalUniversity of Tokyo Magnetic Anomalies, Separationof Internal and External

PotentialsC. R. Bentley Investigation of AntarcticUniversity of Wisconsin Crust and Upper MantleM. A. Mayhew Magsat Anomaly Field Inver-Business & Tech. Systems, Inc. rion and Interpretation forSeabrook, Md. the United StatesJ. L. le Mouel Data Reduction, Studies ofInstitut de Physique du Globe Europe, Central Africa andToulouse, France Secular Variation

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J. C. Dooley The Regional Field andBureau of Mineral Resources Crustal Structure ofCanberra, Australia Australia and AntarcticaB. D. Johnson Crustal Properties ofMacquarie University Australia and SurroundingAustralia RegionsGeologyR. S. Carmichael Crustal Structure andUniversity of Iowa Mineral Resources in the

U.S. MidcontinentD. H. Hall Lithostratographic andUniversity of Manitoba Structural Elements in theCanada Canadian ShieldI. Gi2.l Pacca Structure, Composition andUniversidade de Sao Paulo Thermal State of the CrustBrazil in BrazilD. A. Hastings Precambrian Shields andMichigan Technological Adjacent Areas of WestUniversity Africa and South AmericaD. W. Strangeway Analysis of Anomaly MapsUniversity of Toronto Over Portions of theCanada Canadian and Other ShieldsI. J. Won Compatibility Study of theNorth Carolina State Magsat Data and AeromagneticUniversity, Raleigh Data in the Eastern Piedmont,

United StatesS. E. Haggerty The Minerology of GlobalUniversity of Massachusetts, Magnetic AnomaliesAmherstM. R. Godivier Magnetic Anomaly of BanguiORSTOMParis, FranceField ModelingD. R. Baraclough Spherical Harmonic Repre-Institute of Geological sentation of the MainSciences Geomagnetic FieldEdinburgh, Scotland

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-20-D. P. Stern Study of Enhanced ErrorsNASA Goddard Space Flight and of Secular VariationCenter

M. A. Mayhew Equivalent Source ofBusiness & Tech. Systems, Inc. Modeling of the Main FieldSeabrook, Md.B. P. Gibbs Field Modeling by OptimalBusiness & Tech. System, Inc. Recursive FilteringSeabrook, Md.Marine StudiesC. G. A. Harrison Investigations of MediumUniversity of Miami Wavelength Anomalies in theFlorida Eastern PacificJ. L. LaBrecque Analysis of IntermediateLamont-Doherty GeoJogical Wavelength Anomalies OverObservatory the OceansPallisades, N.Y.R. F. Brammer Satellite Magnetic andThe Analytical Sciences Corp. Gravity Investigation ofReading, Mass. the Eastern Indian OceanMagnetosphere/IonosphereD. M. Klumpar Effects of External CurrentUniversity of Texas, Systems on Magsat Data

Richardson Utilizing Grid Cell ModelingJ. R. Burrows Studies of High LatitudeNational Research Council Current Systems Using Magsatof Canada Vector DataT. A. Potemra Corrective Information onJohns Hopkins University High-Latitude External FieldsR. D. Regan Improved Definition ofPhoenix Corp. Crustal Magnetic AnomaliesMcLean, Va. in Magsat DataCore/Mantle Studies

E. R. Benton Field Forecasting and FluidUniversity of Colorado, Dynamics of the CoreBoulderJ. F. Hermance Electromagnetic Deep-ProbingBrown University of the Earth's Interior:Providence, R.I. Crustal Resource

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LAUNCH VEHICLEThe Scout-G-l launch vehicle is a basic launch vehicledesigned to provide a reliable and relatively inexpensivelaunch system for smaller payloads. The Scout has fourstages, is 22.86 m (75 ft.) long (less the spacecraft) andhas a maximum diameter of 1.01 m (3.3 ft.). The Scout isthe only U.S. launch vehicle which uses solid propellantsexclusively.The propulsion motors are arranged in tandem with tran-sition sections between the stages to tie the structure to-gether and to provide space for instrumentation.the Scout guidance and control system consists of threeminiature integrating gyroscopes, three rate gyroscopes anda pitch axis programmer. During the first-stage burn, thevehicle is controlled by a proportional control system whichfeatures a combination of jet vanes and aerodynamic tip con-trol surfaces. The jet vanes provide mcst of the controlforce during the thrust period while the aerodynamic tip con-trols provide all of the control force during the coast phasefollowing first-stage burnout. During second and third-stageburn, the vehicle attitude is controlled by sets of hydrogenperoxide reaction jets. The fourth stage, which has no activeguidance or control system, receives its initial spatial orien-tation from the control exerted by the first three stages,after which it is spin stabilized to 150 rpm + 20 rpm by meansof four small rocket motors mounted on the skirt at the baseof the fourth stage.The guidance and control system contains a relay unitfor power and ignition switching, an intervalometer to pro-vide precise scheduling of events during flight, a programmerto provide torquing voltages to the pitch and yaw axes, anelectron c signal conditioner to convert the gyro outputs toproper control signals, and a power source consisting of aninverter and dc batteries.The launch vehicle communications system consists ofa radio command destruct system, telemetry and a radar track-ing beacon. The UHF radio command destruct system is pro-vided as a means for destroying the vehicle should a malfunc-tion occur which presents a hazard. The vehicle is equippedwith two completely independent destruct systems built arounda 10-channel command receiver. The destruct command requiresthat three channels be modulated in the proper sequence, thusreducing the possibility of an inadvertant destruct command.

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The telemetry system is a standard Inter Range Instru-mentation Group Pulse Amplitude Modulation frequency modu-lation system which is capable of handling 18 subcarrierchannels. The functional and environmental conditions ofthe vehicle are monitored, and the data is transmitted toground stations through a telemetry transmitter operatingin the 2200- to 2300-MHz frequency range with a power out-put of 10 watts.

The radar tracking beacon is located in the thirdstage of the vehicle. The beacon has a minimum peak poweroutput of 500 watts.

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SCOUT G-1 LAUNCH VEHICLE

MAGSATFOURTH STAGE l SPACECRAFTANDSPACECRAFT 1 FW-4SALTAIR I1IA

.~ ANTARES l11THIRD STAGE

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Detail

HEATSHIELD

MOTOR D 3RDSTAGE U ..R "C LWR C' UPPER FIS STGEAS2ND STAGE L FIN INT

STA STA STA STA, STA STA STA STA STA STA STA STA STA STA-4 ?47 77 84 5310381 13110 191 0 2W818 S3 437 6 4888 49630 8W 2 r 85880wFOURIH STAGE THIRD STAGE SECOND TAGE | FIRSTSTAGE

Scout Launch Vehicle

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LAUNCH TO ORBIT PHASE

The Magsat spacecraft will be launched by a foursolid-rocket stage Scout vehicle. The first stage is theAlgol III A; the second stage is the Castor II A; thethird stage is the new (i..e. Magsat is the first user)Antares IJI; and the fourth stage is the Altair III Arocket. Magsat will be mounted atop the fourth stage,inside the Scout standard 86-cm (34-in.) diameter fairing.After spearation from the spin-stabilized fourthstage, the spacecraft is despun by a yo-yo systemconsisting of a pair of weights, cables and releasemechanisms located at diametrically opposed facets, tomaintain balance torques during despin. Weight releaseis initiated by a separation-switch-activated timer onboard the spacecraft. Despin is accomplished by thetransfer of some or all of the spacecraft angularmomentum into the yo-yo system weights and wires.A series of predetermined attitude control maneuverswill be performed by stored commands to bring thesatellite into alignment with the Sun. There afterthe satellite will be in a closed loop attitude controlmode.

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MAGSAT ORBIT PARAMETERS

Injection conditions:Latitude 15.37 degreesLongitude -124.83 degreesAltitude 357.57 km (222 mi.)Injection Velocity 27,904.43 km/hr (17,339 mph)Time of injection 525.76 sec

Elements:Semimajor axis 6,828.82 km (4,243 mi.)Eccentricity .015Inclination 97.02 degreesArgument of perigee 165.36 degreesRight ascension ofascending node*Anomalistic period 93.773 minHeight of perigee 350.1 km (218 mi.)Height of apogee 550.3 km (342 mi.)

Changes in orbit elements:Perigee rate -3.62 deg. per dayNode rate +0.95 deg. per day

* The right ascension of the ascending node will varydepending upon the date the satellitr is launched.SEQUENCE OF INITIAL FLIGHT EVENTS

Time (sec.) Event-0.13 First Stage Ignition0.00 Liftoff84.56 First Stage Burnout96.04

Second Stage Ignition-2 Separate First Stage125.29 Second Stage Burnout152.21 Separate Payload Heatsh-.eld153.91 Third Stage IgnitionSeparate Second Stage199.56 Third Stage Burnout486.10 Spin Motor IgnitionFourth Stage Squib IgnTi n87.60 Separation Explosive Bolt IgnitionSeparate third Stage

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-28--Time (sec.) Event492.45 Fourth Stage Ignition525.76 Fourth Stage Burnout33 + 30 sec Fourth Stage/Spacecraft Separation

POST LAUNCH SEQUENCEDay No. 1

Estimated timevent after liftoffFire all pyros except sensor platformelease 17 min.Magnetic torquing to orient the B axisto the desired direction in space 17-111 min.ncage nutation damper 18 mi.xtend aerotrim boom 28 min.Turn on gyro 28 min.Change optical bench set point from mi.15 C to 25 (59 to 77 F) 60 mm.se magnetic spin/despin system toreduce spin rate to 0 + 0.15 rpm. 12 hoursommand attitude signal Processorinto IR control mode with roll/yawcontrol and momentum dumping. 18 hoursurn on doppler beacon 20 hoursurn on precision vector magnetometer 20 hoursand scalar magnetometer (to helpmaintain the IM temperature) 20 hoursDay No. 2Fire pyros to release sensor platform 24 hoursxtend magnetometer boom fully at apogee(by delayed command)Adjust aerotrim boom length immediately 25 hoursafter magnetometer boom extension (bydelayed command) 25 hoursurn on precision Sun sensor and AttitudeTransfer System

26 hoursDo pitch and yaw gimbal search forAttitude Transfer System signal ifnecessary 26 hoursDo a roll gimbal search for AttitudeTransfer System signal if necessary 26 hours-more-


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-29-Day No. 3

Estimated timeentafter liftoffRefine the attitude signal processorinput data for best attitude control 50 hoursDay No. 4

Turn on star cameras 96 hours

-more-


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-30-

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MISSION MANAGEMENT TEAM

NASA HeadcuartersDr. Anthony J. Calio Associate Administrator

for Space and TerrestrialApplicationsPitt G.. Thome Director, Resource Ob-

servation DivisionJames P. Murphy Magsat Program ManagerDr. James V. Taranik Magsat Program ScientistJohn M. Yardley Associate Administrator

for Space TransportationSystem Acquisition

Joseph B. Mahon Director, ExpendableLaunch Vehicle Systems

Paul E. Goozh Scout Program Manager

Goddard Space Flight Center

Robert E. Smylie Acting DirectorJohn H. Boeckel Acting Director, Pro-

ject ManagementGilbert W. Ousley Magsat Project ManagerDr. Robert A. Langel Magsat Project ScientistJohn H. Berbert Data ManagerCharles E. White Deputy Project Manager/

TechnicalMartin D. Menton Deputy Project Manager/

ResourcesNorman J. Piterski Mission Operations ManagerDonald L. Margolies Spacecraft Manager

- more -


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-32-John J. O'Brien Instrument ManagerDr. Mario H. Acuna Vector Magnetometer In-strument ScientistDr. Winfield H. Farthing Scalar Magnetometer Tech-

nical OfficerRobert G. Sanford Mission Support ManagerRichard H. Sclafford Network Support ManagerKeni.edy Space CenterRichard G. Smith DirectorGeorge F. Page Director, ExpendableLaunch VehiclesH.R. Va- Goey Manager, Western Opera-tions OfficeGene E. Schlimmer Manager, Magsat Space-craft OperationsLangley Research CenterDonald P. Hearth DirectorLee R. Foster Manager, Scout ProjectOfficeLarzy R. Tant Magsat Coordinator ScoutProject OfficeDonald E. Forney Manager, Langley MissionSupport Field Office

CONTRACTORSApplied Physi.cs Laboratory, Spacecraft contractorJohns Hopiins University -Lewis D. EckardBall Aezospace Systems Division, Scalar Magnetometer managerestern Aerospacc Laboratories -David SnyderVought Corp. -- Milton Green Program Director, Scout

-end-

magsat press kit

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