geodetic explorer-a (explorer xxix) press kit

Upload: bob-andrepont

Post on 09-Apr-2018

221 views

Category:

Documents


0 download

TRANSCRIPT

  • 8/7/2019 Geodetic Explorer-A (Explorer XXIX) Press Kit

    1/44

    NAIIONAL AERONAUTI(S AN D SPACE ADMINISTRATION WO 9-41;',WASHINGTON, DC 20546 TELS. WO -'9FOR RELEASE; FRIDAY P.M.'Sp OCTOBER 29, 1965

    - RELEASE NO: 65-333K PROJECT: GEODETIC EXPLORER-A (GEOS-A)CONTENTS

  • 8/7/2019 Geodetic Explorer-A (Explorer XXIX) Press Kit

    2/44

    * NATIONAL AERONiAUTICS AND SPACE ADMINISTRATION TELS WO 2-4155* * WASHINGTON, D.C. 20546 T WO 3-6925

    FOR RELEASE: FRIDAY P.M. iSOCTOBER 29, 1965RELEASE NO: 65-333

    NASA TO LAUNCHGEODETIC SATELLITE,FIRST OF ITS TYPE

    The National Aeronautics and Space Administration willlaunch from Cape Kennedy no earlier than Nov. 2, a new typeof Explorer satellite designed exclusively for geodetic studies.

    Geodesy is the mathematical determination of the Earth's

  • 8/7/2019 Geodetic Explorer-A (Explorer XXIX) Press Kit

    3/44

    * 1 I

    -2-Examrples of the potential scientif c values to be derivedfrom satellite geodesy are (1) detecting and measuring long-

    term lateral and vertical shifting of major land masses andisland chains, (2) mapping the density, pressure, and compositionof the Earth's interior and generally, increasing mankind'sknowledge of the geoid's structure and past history, (3) developinga capability for forecasting major earthquake activittv, (4)enhancing the use of satellites for navigational purposes, and(5) improving the positional accuracy of satellite tracking

  • 8/7/2019 Geodetic Explorer-A (Explorer XXIX) Press Kit

    4/44

    ;I *

    -3 -interrogating ground stations, and (5) range and range-ratetransponder to determine the changing range and radial velocitycf the satellite.

    Simultaneous operation of the five independent and diversegeodet-Ic-tracking symptems will, permit cross-checking andevaluation of the functioning and accuracies, of the differenttechniques and is expected to enhance the accuracy of eachsystem.

    Upon achieving the

  • 8/7/2019 Geodetic Explorer-A (Explorer XXIX) Press Kit

    5/44

    -4-All relevant d;1:.'a will be openly available to participants

    in the program. Results will be made available to the inter-national scientific community.

    Principal scientific investigators in the GEOS-A projectrepresent Ohio State University, Columbus; University ofCalifornia (Los Angeles); Smithsonian Astrophysical Observatory,(SAO) Cambridge, Mass.; NASA Goddard Space Flight Center,Greenbelt, Md.; U. S. Air Force (Cambridge Research Laboratory)(AFCRL) Cambridge, Mass.; U.S. Navy(Bureau of Naval Weapon-0;

  • 8/7/2019 Geodetic Explorer-A (Explorer XXIX) Press Kit

    6/44

    In-flight optical and radio ranging support to be providedby Goddard includes the already operational NASA Range andRange Raze Stations; Minitrack Optical Tracking Station (MOTS)cameras; the Satellite Tracking and Data Acquisition NetworksSTADAN); and laser tracking facilities.

    The Smithsonian Astrophysical Observatory will supportthe optical tracking with its worldwide network of Baker-Nunncamera stations.

    Additional optical tracking will be provided by camera

  • 8/7/2019 Geodetic Explorer-A (Explorer XXIX) Press Kit

    7/44

    -6-BACKGROUND 11NFORMATION

    GEOS-A Scientific ObjectivesImplementi the overall objectives of the United States

    Geodetic Satellite Program, the GEOS-A project is designedprimarily to connect continental and local geodetic datums(certain specific areas defined and calibrated for referencepurposes) in a one-world datum and to relate all surface datumsto the Ea,0th's common center of mass so that positions of selectedsites can be determined in a new type of three-dimensional coordinate

  • 8/7/2019 Geodetic Explorer-A (Explorer XXIX) Press Kit

    8/44

    -7-In measuring and mapping the Earth's gravitational field

    the goal of the project scientists is i;o determine the structureto an accuracy of five parts in 100 million.

    It is only in recent years that pronounced irregularitiesin the Earth's gravitational field have been detected and thatrequirements have arisen for more precise knowledge of distancesbetween distant points.

    Progress MadeThe U.S. Coast and Geodetic Survey reports that a decade

  • 8/7/2019 Geodetic Explorer-A (Explorer XXIX) Press Kit

    9/44

    -8-Need For New Satellites

    The initial geodetic studies based on satellite dataactually used satellites designed for other purposes. As theusefulness of this approach was quickly exhausted, it becameevident that further progress would require more accurateinstruments and carefully selected orbits.

    The orbits and instrumentation for an early series ofNavy experimental satellites were chosen to provide accurateinformation on the Earth's gravitational field.

  • 8/7/2019 Geodetic Explorer-A (Explorer XXIX) Press Kit

    10/44

    is designed to make maxtmum use of the talents. Competence,and capab4lities which exist in the nationts universities,private research organizations, industry, and other governmentagencies.

    Direct overall responsibility for the program is assignedto the National Aeronautics and Space Administration with programmanagement exercised by the Physics and Astronomy Programs sectionof NASA's Office of Space Science and Applications.

    The national program is based on recommendations of the

  • 8/7/2019 Geodetic Explorer-A (Explorer XXIX) Press Kit

    11/44

    -10-containing radio and optical equipment that must operate inspace. Two GEOS spacecraft are au Gaorlzed.

    The second type is a passive spacecraft, called PAGEOS,resembling Echo I. It will be a single 100-foot diameterinflatable sphere with high visibility. It will not containany active electronic instrumentation. The last stage of thelaunch vehicle will contain a simple radio beacon to aid earlyorbit determination. A PAGEOS launch is expected in 1966.

    Geodesy--Gravimetric and Geometric

  • 8/7/2019 Geodetic Explorer-A (Explorer XXIX) Press Kit

    12/44

  • 8/7/2019 Geodetic Explorer-A (Explorer XXIX) Press Kit

    13/44

  • 8/7/2019 Geodetic Explorer-A (Explorer XXIX) Press Kit

    14/44

    -13-In addition to the equipment foro.aking geodetic measurements,

    the main structure contains the satellite clock, memory computer3ystebm, command system, telemetry system, and three independentpower systems wired to their associated solar cell arrays.

    Despin rods are iaiounted in the satellite for removingresidaal spin of the satellite before the stabilization boomis extended.

    The surface of the satellite oriented toward Earth is

  • 8/7/2019 Geodetic Explorer-A (Explorer XXIX) Press Kit

    15/44

    BOOM END MASS

    BOOM RELEASE ORDNANCEHIGH PRESSURE SQUIB OA6-4- BOOM

    BATTER VS OPTICAL CAPACITOF RANK

    SOLAR CELLSLASER CORNER REFLECTOR, PIALBAO

    RANGETCA FQI^ACON

    RANGE RATE-ANTENNA -A

    TRANSPONDER

    OPT!CAL BEACON ARMY RANGETRANSPONDER

    ELECTRONICBOOKS DUAL OSCILLATOR

    BROADBAND SPIRAL ANTENNA

  • 8/7/2019 Geodetic Explorer-A (Explorer XXIX) Press Kit

    16/44

    -14-

    GEOS-A FACT SHEETLaunch: No earlier than Nov. 2, 1965Apogee: 920 statute miles (1500 kilometers)Perigee: 690 statute miles (1100 kilometers)Inclination: 59 degrees to EquatorOrbital Period: 111.52 minutesLifetime: One year design minimumWeights 385 pounds

  • 8/7/2019 Geodetic Explorer-A (Explorer XXIX) Press Kit

    17/44

    -t15-Clock and Memory: A crystal os illator with frequency divider,

    synchronized to Universal Time, controlstiming markers broadcast on 162 and 324 McDoppler frequencies and 136 Mc telemetryfrequency, and, through the memory, controlsthe timing of optical beacon flashes. Thememory is a special purpose computer witha capacity of 65 digital words of 21 bits

  • 8/7/2019 Geodetic Explorer-A (Explorer XXIX) Press Kit

    18/44

    -16-Telemetry System: Four basic units: (1) two 35-channel (PAM)

    commutators that modulate two subcarrieroscillators that, in turn, phase modulatethe 136.83 megacycle telemetry transmitter,(2) two 8-channel pulse duration modulation(PDM) subcommautators, and (3) three 15-bittelltale registers, (4) telemetry timemarker. The telemetry transmitter radiates

  • 8/7/2019 Geodetic Explorer-A (Explorer XXIX) Press Kit

    19/44

    -17-GEODETIC INSTRUMENTATION

    Optical Beacon SystemFour recessed xenon or "electronic" flash tubes, each

    emitting a light of 1,580 candle-seconds per flash will permitthe satellite to be photographed against the stellar background.

    Photographs made by cameras of the Smithsonian AstrophysicalObservatory, the United States Aj.r Force, the Coast andGeodetic Survey, the Minitrack Optical Tracking System

  • 8/7/2019 Geodetic Explorer-A (Explorer XXIX) Press Kit

    20/44

  • 8/7/2019 Geodetic Explorer-A (Explorer XXIX) Press Kit

    21/44

    -19-These time measurements, coupled with camera-obtained

    angular data, will precisely locate orbiting spacecraftand are expected to provide a very accurate method of trackingsatellites.

    Cube corner prisms are mounted on four of the eight flatpanels on the bottom rim of the spacecraft. These prisms form-the retro-reflectors used for the optical laser range and anglemeasurements.

  • 8/7/2019 Geodetic Explorer-A (Explorer XXIX) Press Kit

    22/44

    - 20-

    The Navy Doppler Tracking Network (TRANET) will be usedto provide data ;or reduction and analysis by the Bureauof Naval Weapons that .wI.ll hello-;:.blJsh the structure ofthe Earth's gravitational field to an accuracy of about fiveparts in 100 million. The Navy has 15 permanent Doppler trackingstations.

    The Doppler technique involves timing and measuring thefrequency shift of radio transmissions from the moving satelliteas observed by ground-based receivers.

  • 8/7/2019 Geodetic Explorer-A (Explorer XXIX) Press Kit

    23/44

    -21-Irregularities in the Earth's shape, however, cause the

    satellite orbit to change slightly from a perfectly smoothelliptical orbit. The Doppler signals reflect there irregularitiesin the orbit, and the analysis of them provides a better pictureof the size and the shape of the Earth, or geoid.

    Range and Range-Rate SystemThe NASA Range and Range-Rate (R&RR) system was developed

    by. he Goddard Space Flight Center and has the capability of

  • 8/7/2019 Geodetic Explorer-A (Explorer XXIX) Press Kit

    24/44

    -22-

    Range (;etermination is essentially a time measurement. Acarrier signal is modulated with several related frequenciesa,.; transmitted fro~m the ground to the S-band transponder -Inthe satellitel. The transponder retransmits a slightly alteredsignal to tv_ ,-round station. A phase comparison between thesignal sent and the one received at the ground provides nherange determination.

    The range-rate is obtained by measuring the Doppler shi'tof the signal transmitted by the spacecraft--the time required

  • 8/7/2019 Geodetic Explorer-A (Explorer XXIX) Press Kit

    25/44

    -23-Station-to-s.. ae1lite range is measured by observing the

    total phase sh.A.. of an accurately known modu-atDin frequency.The shift in phase is proportional to distance and so providesa measurement of range in wavelengths of the modulated frequency.

    Geodetic measurements are accomplished by sequentialinterrogation of the satellite, via the transponder, by fouridentical ground stations. Three of the stations are in knownposition; the fourth's location is to be determined.

    Calculation of

  • 8/7/2019 Geodetic Explorer-A (Explorer XXIX) Press Kit

    26/44

    transmitted and received modulation frequencies are phasecomb red to obtain an independent range measurement.

    A sequence of four such interrogations, one from eachstation, is accomplished in 50 milliseconds, and these sequencescan be repeated at a rate of 20 a second throughout the timeinterval selected for observation.

    The satellite trajectory is then obtained by collatingrange measurements made from the three known locations. The

  • 8/7/2019 Geodetic Explorer-A (Explorer XXIX) Press Kit

    27/44

  • 8/7/2019 Geodetic Explorer-A (Explorer XXIX) Press Kit

    28/44

    30e - -- - ------- A s

    NASA TRACKING FACILITIESs - MANNED SPACE FLIGHT NETWORK-SATELLITE TRACKING AND DATA ACQUISITION NETWORKA-DEEP SPACE INSTRUMENTATION FACILITIES1-OPTICAL TRACKING NETWORK

  • 8/7/2019 Geodetic Explorer-A (Explorer XXIX) Press Kit

    29/44

    -26-SATELLITE CLOCK xNDEMORY

    The satellite clock, based on extremely precise oscillationsof the ultra--stable crystal oscillator of the radio Dopplersystem, will be used to tri-ler theoptical beacon flashes andto control timing markers broadcast from the satellite.

    A frequency divider, the clock functionally divides theOscillator frequency by a ratio which can be adjusted over atotal range of 38.6 parts per million. This ratio will be

  • 8/7/2019 Geodetic Explorer-A (Explorer XXIX) Press Kit

    30/44

    -27-The 1,365 serial data bits are treated as 65 digitalwords of 21 bits each. These bits are assigned differentfunctions and are used to execute the message injected intothe memory.

    Messages are coded according to the bit assignments sothat the flash sequence will be initiated at the desired time,the requested number of beacons will flash, and the clock ratecan be set.

  • 8/7/2019 Geodetic Explorer-A (Explorer XXIX) Press Kit

    31/44

    -28-POWER SUPPLY

    Primarv source of power for operating the GEOS-Ainstrumentation and transmitters will be 4,992 N on Ptype silicon solar cells arranged in 16 panels on the sidesurfaces.

    Shielding from radiation will be provided by an 0.02 inchthick fused silica cover slide with a blue reflecting opticalfilter.

    Three independent power supplies, each with its own

  • 8/7/2019 Geodetic Explorer-A (Explorer XXIX) Press Kit

    32/44

    -29-In the event of the failure of the main power supply the

    satellite command system will automatically shift to the nextoperational supply.

    GRAVITY STABILIZATION SYSTEMCritical to optimum use of the radio and optical beacons

    on GEOS-A is the gravity-gradient attitude stabilization systemto keep the satellite antennas, laser reflectors, and opticalbeacons oointing earthward at all time.

  • 8/7/2019 Geodetic Explorer-A (Explorer XXIX) Press Kit

    33/44

    -30-on the Earth-facing side is markedly different than that ofthe opposite side. The Moon still oscillates slightly, turningfrom side to side and permitting Earth observers to see about57 per cent of its surface over the years, but only 50 percent at one time.

    The attitude of the GEOS spacecraft will be detected bytwo systems.

    One uses six solar cells, calibrated to give directional

  • 8/7/2019 Geodetic Explorer-A (Explorer XXIX) Press Kit

    34/44

  • 8/7/2019 Geodetic Explorer-A (Explorer XXIX) Press Kit

    35/44

    -32-

    PRINCIPAL INVESTIGATORSThe individual responsibilities of the scientific

    investigators differ somewhat. However, all will cooperateand assist in compiling their results for a handbook that willaccumulate findings of the United States Geodetic SatelliteProgram.

    This handbook will include (1) a mathematical analysisof the Earth's gravitational field as seen from satellite

  • 8/7/2019 Geodetic Explorer-A (Explorer XXIX) Press Kit

    36/44

  • 8/7/2019 Geodetic Explorer-A (Explorer XXIX) Press Kit

    37/44

    -34-

    Owen W. Williams, Air Force Cambridge Research Laboratory,Cambridge, Mass.,, who will obtain and use observations of theoptical beacon flash sequences to pinpoint major world geodeticdatums and observational sites with a three-dimensional un-certainty of 10 meters or less.

    Capt. L. W. Swanson of the Coast and Geodetic Surveywill use the later passive satellite (PAGEOS) primarily in

  • 8/7/2019 Geodetic Explorer-A (Explorer XXIX) Press Kit

    38/44

  • 8/7/2019 Geodetic Explorer-A (Explorer XXIX) Press Kit

    39/44

    -36-

    The Delta launch vehicle project is u.nder technicalmanagement of the Goddar(l Space Flight Center, Greenbelt,Md. Douglas Aircraft Co., is the prime contractor.

    Dult;. SLatisticsThe three-stage Delta for the GEOS-A missior1 ;as the

    following characteri-,ticsJHeight: 92 feet (includes shroud)

  • 8/7/2019 Geodetic Explorer-A (Explorer XXIX) Press Kit

    40/44

    -37-

    Diameter: 31 inchesHeight: 19.8 feetWeight: 2 7,5 1 0 pounds (9,170 each)Thrust: 161,550 pounds (53,850 each),hurning Time: 43 seconds

    Secnd ac: Produced by the Douglas Ai'rcraft Co.,utilizing the Aerojet General Corp.

  • 8/7/2019 Geodetic Explorer-A (Explorer XXIX) Press Kit

    41/44

    -38-

    Third Stage: Allegany B3allistics Laboratory X-258 motor.Propellants: Solid'sHeight: 3 feetDiameter: 1 feetWeight: 570 poundsThrust: 5,760 poundsBurning -rime: 22.5 seconds

  • 8/7/2019 Geodetic Explorer-A (Explorer XXIX) Press Kit

    42/44

    Thruist-Augmented Improved Delta Flight Events (nominal) For GEOS-A MissionVELOCITY

    ALTITUDE SURFACE RANGE MILES PEREVENT TIME (STATUTE MILES) (STATUTE MILES) HOUR

    Strap-on Solids 70 sec. 17 9 2,607Separation

    Thor burnout 2 min. 29 sec. 74 87 9,1832nd. stage ignition 2 min. 33 sec. 80 97 9;161Shroud separation 2 min. 36 sec. 82 101 9,1642nd. stage burnout 9 min. 2 sec. 412 1,044 14,2473rd. stage ignition 18 nin. 41 sec. 690 2,777 12,9953rd. stage burnout 19 min. 3 sec. 690 2,849 16,516

    - more -

  • 8/7/2019 Geodetic Explorer-A (Explorer XXIX) Press Kit

    43/44

    -40-

    Delta Growth (1960-1965)

    Delta Configuration Earth Orbit (300 miles) EscapeDM19 (1960) 525 lbs. 70 lbs.DSV-3A & 3B (1962) 800 lbs. * 95 lbs.3-foot longer

    second stage

    DELTA LAUNCH VEHICLE RECORD

  • 8/7/2019 Geodetic Explorer-A (Explorer XXIX) Press Kit

    44/44

    MISSION RESULTS LAUNCH WEIGHT(Pounds)

    Echo failed May 13, 1960 132Echo I successful August 12, 1960 200TIROS II successful November 23, 1960 280Explorer X (P-14) successful March 25, 1961 80TIROS III successful July 12, 1961 280Explorer XII (S-C) successful August 16, 1961 90TIROS IV successful February 8, 1962 280OSO-I successful March 7, 1962 500Ariel-l (UK-1) successful April 26, 1962 160TIROS V successful June 19, 1962 300Telstar I successful July 10, 1962 171TIROS VI succe'3ful September 18, 1962 280Explorer X'IV (S-3A)succesr.ful October 2, 1962 89Explorer XV (S--3B) successful October 27, 1962 98Relay I successful December 13, 1962 172Syncom I successful February 14, 1963 150Explorer XVII successful April 2, 1963 150Telstar II su 'fessful May 7, 1963 410TGROS VII successful June 19, 1963 300Syncom II successful July 26, 1963 150Explorer XVIII 024P-4successful November 26, 1963 138TIROS VIII successful December 21, 1963 265Relay II successful January 21, 1964 261S-66 failed March 19, 1964 116Syncom III successful August 19, 1964 145Explorer XXI(IMP-2) low orbic October 3, 1964 135EPE-D successful December 21, 1964 110TIROS IX successful January 22, 1965 305OSO II successful February 3, 1965 545Early Bird successful April 6, 1965 145IMP III successful May 29, 1965 136TIROS X successful July 1, 1965 290OSO-C failed August 25, 1965 620

    - - - -_ _