tiros i (eye) press kit

8/8/2019 Tiros I (Eye) Press Kit

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NATIONAL AERONAUTICS AND SPACE ADMINISTRATION TELS WC) 2-41','.IO WASHINGTON, D C 20546 WOL- ' ,9?;FOR RELEASE: TUESDAY AM 'SJanuary 19, 1965

RELEASE NO: 65-7

PROJECT: TIROS I (Eye)

CONTENTS

GENERAL RELEASE .............................. 1-2TECHNICAL BACKGROUND ..................... 3-4FLIGHT PLAN.,-o.-o-.o.......o.......o ...........................-7

t ~~~Polar, Sun-Synchronous Orbito..ooo.,oo...............TIROS SPACECRAFT. ..... ... ... .. ......... ,. . . 8

Stabilization and Control Subsystems...... 9-10Attitude Sensors... ..... .... o.o.o.... . 10-11Television Cameras........... 11-12Camera Triggering Subsystemu.............o... 12-13


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*NAAIONAL AERONAUTICS AND SPACE ADMINISTRATION TELS WO 2-4155E WS WASHINGTON, D.C. 20546 WO 3-6925FOR RELEASL TUESDAY AMI SJanuary 19, 1965

RELEASE NO: 65-7

NASA TO LAUNCHFIRST 'CARTWHEEL'WEATHER SATELLITE

The National Aeronautics and Space Administration willlaunch a new version of its TIROS weather satellite no earlierthan Jan. 19 from Cape Kennedy, Fla.

The new satellite, designated TIROS I (eye), will rollalong its near-polar orbit much like a cartwheel. Cameraswill view the Earth from its side or rim unlike cameras onearlier TIROS which pointed from the bottom of the satellite.

TIROS I is designed to roll at a rate of 10 revolutionsa minute. Cameras in its rim will view the Earth once during


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The launch marks the first NASA attempt to place asatellite in near-polar sun-synchronous orbit from Cape Kennedy.TIROS I is scheduled to enter orbit over the Pacific Oceanabout 300 miles west of Quito, Ecuador after its Delta launchvehicle has performed three dog-leg maneuvers.

The Delta launch vehicle, which has placed 25 NASA satel-lites in orbit, is programmed to put the 305-pound TIROS Iinto a circular orbit 460 statute miles high, inclined 31.6degrees to the equator, and with an orbital period of 100minutes.

Primary objective of the TIROS I research and developmentlaunching is to test the cartwheel configuration. It isthe forerunner for the joint NASA and U. S. Weather Bureauoperational weather satellite system called the TIROSOperational Satellite (TOS) system. The TOS program consistsof six launches and is scheduled to begin next winter.

TIROS (Television Infrared Observation Satellite) is aweather satellite project of NASAts Office of Space Science


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-3-TECHNICAL BACKGROUND

TIROS I (eye) - Statistics

Spacecraft . . . . . . . . . . . . Cylindrical, 18-sidedpolygon, 22 inches high and2 inches diameter, weighing305 pounds

Mission objectives . . . . . . . . Test cartwheel configurationIncrease Earth coveragefrom a satelliteIncrease frequency andaccuracy of measurementsImprove accuracy and reso-lution of television picturesDevelop faster means forpicture distribution

Launch Information:Vehicle . . . . . . . . . . . Three-stage Delta developing170,000 pounds of thrust atliftoffLaunch Pad . . . . . . . . . Complex 17, Pad A at theEastern Test Range, CapeKennedy, Fla.


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Velocity . . . . . . . . . . . Approximately 18,000 milesper hourCameras . . . . . . . . . . . . . . Two, 2-inch vidicons Whichtake more than 400 picturesdaily with a resolution of

about two miles at picturecenterPower System . . . . . . . . . . . 9,lu solar cells (N on P)which convert sun energyto electrical enercy tokeep 63-nickel cadmiumbatteries chargedTracking . . . . . . . . . . . . . Fifteen stations of theworld-wide Space Tracl:infland Data Acquisition Network(STADAN) operated by theGoddard Space Flight CenterCommand and Data . . . . . . * * * Wallops Island, Va.Acquisition Stations Gilmore Creek, AlaskaSan Nicolas Island. Calif.

Program management . . . . . . . . Office of MeteoroloricalPrograms, Office of SpaceScience and Applications,NASA HeadquartersProject managment . . . . . . . . . Goddard Space Flight Center(Spacecraft, Launch vehicleand Launch Operations)Major contractors:


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THE FLIGHT PLAN

TIROS I will be the first NASA satellite ever shot intoI .polar orbit from Cape Kennedy. Launch vehicle for the mis-

sion is the NASA-developed, three-stage Delta.

Delta will leave Complex 17, Pad A a'd must performthree precise "dog leg" maneuvers before it reachps its or-bit injection point over the Pacific Ocean.'|

Launch is scheduled for 3 a.m. The launch window ;sabout 45 minutes.

During first stage burning, from T plus 90 to T plus130 seconds, a yaw right command from the guidance systemwill turn the vehicle to the right.

Six seconds after the second stage ignites, about 153launch, the guidance system will send another


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If Delta performs as planned, TIROS I will beinjected intoorbit over the Pacific Ocean about 300 miles West of Quito,Ecuador (84 degrees West longitude, 0 degrees latitude).

During the first orbit the satellite will operate inmuch the same manner as the earlier TIROS spacecraft. It willbe spin stabilized at about 10 rpm with the bottom of thespacecraft, or baseplate, looking at the Earth.

As TIROS starts it second orbit a gradual orientationmaneuver, performed by ground controllers, begins to turn thesatellite on its side into the cartwheel position. On commandfrom the ground, electrical currents pass through a magnetic-attitude coil inside the spacecraft which turns the satelliteon its side at a rate of approximately 10 degrees per orbit.

When the satellite is about half way on its side (45degrees to-the vertical plane of the Earth) the current will be

to about half so TIROS will turn five degrees each orbit.


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Pictures will be sent to TIROS ground stations on atleast 10 of the lit daily orbits. However, weather picturescan be recorded during three "blind" orbits (orbits whic>.do not pass over one of the three TIROS ground stations)for playback on a later pass.

Spacecraft performance data as well as weather pictureswill be sent to three ground stations called Command andData Acquisition (CDA) stations. These stations are atWallops Island, Va., San Nicolaf; Island off the Californiacoast, and Gilmore Creed, Alaska.

POLAR, SUN-SYNCHRONOUS ORBIT

Complete coverage of the world's cloud cover, comparedto about 25 per cent with earlier TIROS, will be possibledue to a combination of the cartwheel configuration and anorbit which is polar and sun-synchronous.


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TIROS SPACECRAFTAbout the only likeness between TIROS I and its eight

predecessors is the hat-box shaped structure. It is an 18-sidedpolygon which weighs 305 pounds, stands 22 inches high andmeasures 42 inches in diameter.

Some of the new components to undergo testing for thefirst time aboard TIROS are digital clocks. control system,horizon scanners, solid state commutators for telemetry anda new triggering system for the cameras.

The 9,100 solar cells mounted on the top and sides ofthe satellite structure have been changed from positive onnegative (P on N) to negative on positive (N on P), which donot deteriorate as rapidly in the artificial ~adiation belt.

Protruding frog the top of the satellite is an 18-inchreceiving antenna which receives commands from data acquisitionstations.


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Thl two TV cameras trre mounted 1;0 dec;rees apart on t>lerim of thre satellite rather than in the bottom. This enableseach camera to view the Earth once every six seconds asTIROS rolls along its orbit.

Sr'ABILIZATION AND CONTROL SUBSYSTEMS

Two dynamic control (DYCON) units in TIROS I controlthe satellite's spin rate, camera timing and magnetic attitudecoil currents wrhich steer TIROS to the cartwheel attitu(dcan:! maintain it in that position.

Shortly before the burned out second star-e of Deltaseparates from the third stage, the entire vehicle spins upto approximatel: 125 rpm.

To reiuce the spin rate to 10 rpm, a timer triggers twowei-;hts attached to cables wrapped around the outside of thesatellite. As the weights uncoil, they recuce the spin tothe desired rate and then automatically drop away from the


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The magnetic coil is made of aluminum and measures30 inches long and is tightly wrapped inside a rectangularspool in the spacecrafts The spin rate can be kept almostconstant by sending small charges of electric current throughthe coil.

As a backup, five pairs of firecracker-size solidpropellant rockets mounted on the rim of the spacecraft canbe fired upon command from a ground station.

Each rocket motor develops an impulse of.'-4pproximately1.4 pounds per second, and when fired in pairs, can increasethe spin rate by about three rpm.

Attitude Sensors

Two infrared horizon sensors arranged in a V configurationdetermine the satellite's attitude in space. The plane ofthe V contains the spin axis and the bisector of the anglebetween the optical axes is normal to the spin vector.


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Because accuracy is determined by the resolution andreliability of each of the data points, at least 10 minutesof roll error will be required in a given pass.

Television Cameras

The camera subsystems are two identical '-inch vidiconcameras, similar to those carried on previous TIROS missions.They have a resolution of about two miles at picture center.

These cameras, mounted on the side of the spacecraft,are canted 26 degrees to each side of the plane of thesatellite's rotation so they can view the Earth once ever,revolution (every six seconds). An on-board timer programsthe cameras to take pictures only when the satellite islookin&r straight down at Earth.

The TV tube is a 500-scan line vidicon with a persistencethat permits a two-second scan with less than 20 per centde 7,radatioh in picture quality.

Each wide an-le camera, using 104-degree lenses, willnominally take 16 pictures per orbit at 12'3 second intervals


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Television pictures transmitted from the spacecraftare reconstructed on special Icinescopes at the groundstation and are photographed by 35mm cameras.

Transmission time for a full orbit of pictures takesabout three minutes and begins when the satellite receivesa radio command from the ground.

Sufficient tape is provided in each of the two taperecorders for storing 48 picture frames at a speed of 50inches per second. The tapes are erased immediately afterplayback and again just before recording.

Camera Triggering Subsystem

Because of the orientation of the cameras in relationto the spacecraft a new triggering system is required for

TIROS I so pictures are taken only when the camerasare

looking vertically at Earth.

Each of the cameras has two independent triggering systems,


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The Spin-Synchronized Trigger system can operate onlywhen the spacecraft is spinning precisely at 9.8 rpm.Horizon scanners determine the satellitets spin rate so thetriggering system will turn the cameras and tape recorderson when the Earth is directly below.

Power SupplyThe power supply delivers up to 2.2 amperes and consists

of solar cells, storage batteries, voltage regulatorsand protective circuits.

Solar energy is converted to electricity by 9j100N on P solar cells, 1 cm by 2 cm, attached to the top andsides of the spacecraft cover assembly. The cells arearranged in shingles of five series-connected cells.

Each cell has a bonded coat of fused silica to improvethermal emissivity and a vacuum-deposited anti-reflective


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Diodes in the solar cells prevent the storage batteriesfrom discharging into the solar cells during orbital night.

DELTA LAUNCH VEHICLEThe Delta project management plus launch operations is

under the direction of the Goddard Space Flight Center.

The Delta vehicle has- the following general characteristics:Height 90 feetMaximum diameter 8 feetLift-off weight about 57 tons

First stage: Modified Air Force Thor, produced byDouglas Aircraft Co.

Fuel: Liquid (Kerosene with liquid oxygen as oxidizer)Thrust: 170,000 poundsBurningtime: about 2 minutes and 27 seconds


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Third stage: Allegany Ballistics Laboratory X-258 motorFuel: SolidThrust: Approximately 5,700 poundsBurningtime: 26 secondsWleight: 576 pounds

PROJECT OFFICIALS

NASA Headauarters:Dr. Homer E. Newell, Associate Administrator for SpaceScience and ApplicationsDr. Morris Tepper, Director, Office of MeteorologicalProgramsMichael L. Garbacz, Program Manager, MeteorologicalFlight ProjectsVincent L. Johnson, Director of Launch Vehidle Pro-pulsion Prog-ramns DivisionT. B. Norris, Delta Proogram Manager

Goddard Space Flight Center:Dr. Harr,- J. Goett, DirectorNelson W. Spencer, Chief, Aw'onomy & Meteorology Division


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U. S. Weather Bureau:Dr. Robert White, DirectorDavid S. Johnson, Director, National Weather SatelliteCenter

Douglas Aircraft Co.:Marcus F. Cooper, Director, Florida Test CenterJack Klien, Director, Delta Programs

Radio Corp. of America:Abraham Schnapf, TIROS Project Manager

-more-


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WEATHER SATELLITE RECORDPictures

Satellite Launch Date Lifetime Inclination TakenTIROS I April 1, 1960 21 mos. 48 degrees 22,952TIROS II Nov. 23, 1960 10 mos. 48 degrees 36,156TIROS III July 12, 1961 41 mos. 48 degrees 35,033TIROS IV Feb. 8, 1962 4j mos. 48 degrees 32,593TIROS V June 19, 1962 I0 mos. 58 degrees 58,226TIROS VI Sept. 18, 1962 13 mos. 58 degrees 66,674TIROS VII June 19, 1963 still 58 degrees 95,573*operatingTIROS VIII Dec. 21, 1963 still 58 degrees 66,444*

operatingNIMBUS I Aug. 28, 1964 26 days near polar/ 27,00082 degreesTotal pictures 440,631

*As of Mid-January

Eight TIROS otorm trackers plus the Nimbus I weather ob-server have spotted almost every tropical storm and hurricane


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STANDARD TIROS/OR ENT ATION~


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