nimbus-d - press kit

8/8/2019 Nimbus-D - Press Kit

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ESS

IT

F R I D A Y P.M.A p r i l 3, 1970RELEASE N O: 70-47

contents

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(NAS A CR OR TMX OR AD NUMBER) (CATEGOI

3/26/70


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F R I D A Y P.M.A p r i l 3, 1 9 7 0RELEASE NO: 70-47

NIMBUS-D LAUNCH A P R IL 8

The fifth in a series of seven advanced research anddevelopment weather satellites is scheduled to be launchedno earlier than April 8, 1970, from the Western Test Range,Lompoc, Calif

Weighing a record 1,366 pounds, the newest satellitein the serieso Nimbus-D, (Nimbus-4 in orbit) will be placedin a nearly circular 690-mile polar orbit by a Thorad/Agena-D rocket. Circling the Earth every 107 minutes andviewing the entire planet twice daily, Nimbus-D is expected

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- 2 -to transmit the most information on the atmosphere everreturned fram space.

The objectives of the Nimbus research and developmentprogram are to explore and understand the nature and behaviorof the atmosphere and to reduce the economic impact ofadverse weather on all nations.

Scientific objectives of Nimbus-D are to develop andexpand the capabilities to measure the atmospheric structureon a global scale, particularly the vertical profiles oftemperature, ozone and water vapor. This was first donewith Nimbus-3, launched April 14 last year and stilloperating.

The launch window for Nimbus-D is 3:lO to 3:40 a.m.,EST.

In addition to the Nimbus-D meteorological experiments,the Agena-D upper-stage vehicle will carry a Department ofDefense "piggy-back" payload into its own separate circularorbit, 675 miles high.

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- 3 -The U . S . Army Corps of Engineers secondary payload,

designated TOPO-A, weighs 40 pounds, will be mounted on theaft rack of the Agena-D and will remain dormant untilNimbus D/Agena separation when its timer will be initiatedand TOPO-A separated,

TOPO-A will be carried by NASA for the DOD as part

of an interagency program to use available booster powerfor maximum space-research cost effectiveness.

Three new experiments are being carried by Nimbus-Das well as three significantly improved versions of sensorswhich have been flown on earlier Nimbus missions. Inaddition, there are three experiments similar to thoseaboard Nimbus 3 .

The new experiments cover potentially important regionsof the electromagnetic spectrum of the Earth's atmospherewhich have yet to be investigated on a global scale.

Being tested for the first time are:

-- The Backscatter Ultraviolet Spectrometer (BW) willmonitor the spatial distribution of atmospheric ozone by

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- 4 -measuring the intensity of ultraviolet radiation backscatteredfrom the Earth's atmosphere. Knowledge of atmospheric ozonedistribution on a global basis is needed for studies of theenergy balance and photo-chemistry of the stratosphere, themass exchange between the lower stratosphere and troposphere,and general atmosphere circulation.

-- The Filter Wedge &ectrometer (FWS) will monitor thedistribution of water vapor in the atmosphere. Determinationof the total amount of water vapor and its vertical distri-bution is of primary interest in weather prediction.

-- The Selective Chopper sadiometer (SCR) will determinethe temperature profile of the atmosphere from Earth cloudtop level to about 40 miles altitude. The Radiometer allowstemperatures to be taken along a strip seven miles longin the direction of flight by 70 miles wide. Radiationmeasurements are achieved with a very high spectral resolutiondue to carbon dioxide absorption cell filters. The SCR wasprovided by the United Kingdom through its National ResearchCouncil.

The three significantly improved meteorological experi-

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- 5 -ments which have flown on earlier Nimbus spacecraft are:

-- -nfrared Interferometer Spectrometer ( I R I S ) willprovide local information on vertical and horizontal distri-bution of temperatures, water vapor and ozone throughoutthe atmosphere. This instrument features improved spectraland spatial resolution.

-- -atellite Lnfrared Sectrometer ( S I R S ) throughdiffering instrument techniques than I R I S will also providedata on vertical temperature and water vapor in the Earth'satmosphere. This will be the first time the S I R S willprovide water vapor data. S I R S was provided by the Depart-

ment of Commerce, Environmental Science Services Adminis-tration, ESSA,

-- -nterrogation Recording and -ocation &stem ( I R L S )will provide for more complete collection of global datafrom remote platforms such as balloons, oceanographic data,

buoys and automatic weather stations in inaccess-ible landareas or aboard ships. This system uses up to fives times

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as many platforms as the Nimbus I11 system and requires

less transmitter power on the platforms.

IRLS platforms will be placed on up to 30 balloonsand about 15 surface platforms to gather information onthe atmosphere's wind circulation. Its ranging systempermits accurate platform locations to within one mile

by triangulation techniques after two successful interro-gations.

The IRLS system can be applied to oceanography, geology,hydrology and ecology.

The three experiments which are quite similar tothose aboard Nimbus 111 are:

-- -emperature Eumidity Infrared Eadiometer (THIR)will measure infrared radiation from Earth and provideround the clock Earth photos as well as temperature mappingof clouds, land and ocean surface temperatures and relativehumidity readings. The local cloud mapping pictures can be

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transmitted immediately to small Automatic PictureTransmission ground stations.

-- -mage Dissector camera =stem (IDCS) will providelocal weather pictures to APT ground stations as well asrecord cloud cover photos of world cloud structure,

-- -onitor of gltraviolet Solar Energy (MUSE) willmeasure the ultraviolet radiation flux from the Sun infive broad bands. These flux variations are related tochanges in the upper atmosphere.

The T H I R and IDCS provide basic supporting data neededfor the other experiments aboard the spacecraft.

In addition to new experiments, Nimbus-D has anattitude control system which will not only allow the space-craft to maintain its stabilization constantly pointingtoward Earth within an accuracy of one degree, but alsopermit initial acquisition and reacquisition of the Earthfrom any attitude.

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Modularized in construction to allow last minuteadjustments in case of component failure prior to launch,the new attitude control system is expected to be moreversatile than previous systems used in the Nimbus program.In case of main system failure, a passive gravity gradientsystem has been added which would use the Earth's gravitationalfield to keep the spacecraft oriented properly. This con-sists of a 45-foot gravity gradient boom which can beextended on command.

Another significant improvement over previous Nimbussatellites is the improved flexibility of the commandtelemetry system which allows more commands--512 comparedto 128--to be sent to Nimbus-D, and also permits more datato be received from the satellite.

Nimbus-I, launched August 28, 1964, worked for aboutone month before it stopped operating due to a failure ofthe solar array drive system. During its lifetime, itproved that a weather satellite could maintain three axes

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- 9 -stability, and it provided man with the first highresolution TV and infrared weather photos,

Nimbus 11, designed for a six-month lifetime, waslaunched on May 15, 1966, operated far beyond this minimumgoal before it became silent January 18, 1969. Its horizonscanner, which keeps the spacecraft properly oriented,stopped working and the satellite began to tumble. Thesatellite's beacon has been shut off.

The 32-month lifetime of Nimbus-2 is considered oneof the most notable accomplishments in Earth-oriented space-craft longevity.

Nimbus-B was destroyed in May 1968 after the launchvehicle veered off course.

Nimbus-3, first weather-eye to measure the verticaltemperature profile of the Earth's atmosphere, continuesto operate after almost a year of orbital operation. Allof the experiments except the IRIS are working, includingthe SNAP-19 nuclear powered generator.

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- 10 -Nimbus-E and F, scheduled for launching in 1972 and

1973, respectively, will test advanced technology andexperiments for meteorology and other applications disciplines.

Nimbus is managed by NASA's Office of Space Science andApplications. NASA's Goddard Space Flight Center, Greenbelt,Md., is responsible for both the spacecraft and the launchvehicle

Launch operations will be conducted by the U.S. AirForce 6595th Aerospace Test Wing under the technical super-vision of NASA's Unmanned Launch Operations, Kennedy SpaceCenter, Western Test Range Operation Division.

General Electric Co., Space Systems Organization,Valley Forge, Pa., is the Nimbus integration and testcontractor. General Electric also integrated the three-axis stabilization system.

McDonnell Douglas Astronautics Company, HuntingtonBeach, Calif., built the Thorad booster and Lockheed Missilesand Space Co., Sunnyvale, Calif., built the Agena-D upperstage.

(END OF GENERAL RELEASE: BACKGROUND INFORMATION FOLLOWS)-more-


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NIMBUS D Spacecraft

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Launch Information:Ve h ic l e

Pad

AzimuthDateWindow

O r b i t a l Elements :O r b i tP e r i o dI n c l i n a t i o n

S p a c e c r a f t :

Space c r a f t l i f e t i m e :S t a b i l i z a t i o n :

M is s ion Ob je c t i ve s :Meteorology

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NIMBUS-D FACTS

Two s t a g e , T h o r a d ( l o n g tankT h o r ) Agena DWestern T e s t R m ge , C a l i f .SLC-2 E a s tl94O TrueNo e a r l i e r t h a n A p r i l 8 , 19703 : l O a . m . EST - 3 : 4 0 a . m . ESTC i r c u l a r , 6 9 0 s t a t u t e m i l e s h i g h1 0 7 minutesN e a r l y polar and Sun-synchronous8 0 " r e t r o g r a d e to t h e E q ua t orB u t t e r f l y - s h a p e d , 1 0 - f e e t - t a l l , 11f e e t w i d e , w i t h a f i v e - f o o t d i a m e t e rs e n s o r y r i n g f o r hous ing e xpe r im e n t sa nd e l e c t r o n i c s we i gh i ng 1 , 36 6 l b s .S i x monthsE a r t h - o r i e n t e d a nd t h r e e ax ess t a b i l i z e d to with in one degree

A c q u i s i t i o n o f a su f f i c i e n t nupbe1-of g l ob a l s amples o f a tm os phe r i cr a d i a t i o n m eas ur em en ts f o r t h e p u r -pose o f c om pa r ing ve r t i c a l t e m pe r a -tu r e , wa t e r va po r , and ozonep r o f i l e s and o f p r o v i d i n g a b a s i sf o r c o mp ar in g t h e m e r i t s o f t h es e ve r a l i n s t r um e n t a ppr oac hes .

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-13-Meteorology (Con ' t . )

S e conda r y Ob je c t i v e s :

Comparative d a t a are t o b e o b t a i n e df rom t h e s u c c e s s f u l o p e r a t i o n o f a tl e a s t t h r e e o f t h e f i v e s p e c t r o-m e t r i c e x p er i m en t s : The S a t e l l i t eI n f r a r e d S p ec tr o me t er ( S I R S ) , t h eI n f r a r e d I n t e r f e r o m e t e r S p ec tr o-meter ( I R I S ) , t h e F i l t e r WedgeS pe c t r om e te r (FWS), t h e S e l e c t i v eChopper Radiometer ( S C R ) , or t h eB a c ks c at t e r U l t r a v i o l e t ( B W )S p e c t r o m e t er , o r fr om s u c c e s s f u lo p e r a t i o n o f e i t h e r t h e FWS o r S C Rp l u s e i t h e r t h e SIRS o r I R I S .A . Demons t r a t ion o f t h e f e a s i b i l i t yo f d e t er m i ni n g wind v e l o c i t y f i e l d sby t r a c k i n g o f m u l t i p l e ba l l o o n s .B . D em on st ra te s a t i s f a c t o r y o p e r a t i o no f an advanced modular - three-axisa t t i t u d e c o n t r o l s y s t e m f o r ap e r i o d o f a t l e a s t s i x months.

M e te o r o log i c a l E xper im en t s :I n f r a r e d I n t e r f e r o m e t e rS pe c t r om e te r ( I R I S )

S a t e l l i t e I n f r a r e dS pe c t r om e te r (SIRS)

I n t e r r o g a t i o n R e c o r d i n gand L oc a t ion S y s t e m( I R L S )

M o n i t o r o f U l t r a v i o l e tS o l a r E ne rg y (MUS E )

Globa l ly m ea su re i n f r a r e d e ne r gy andi n f e r t h e a tm os ph er e s v e r t i c a lt e m pe r a tu r e , water vapor and ozoned i s t r i b u t i o n .M eas ur e i n f r a r e d en e rg y a nd i n f e rt h e a tm o sp h er e 's v e r t i c a l t e m p er a t ur eand water v a p o r g l o b a l l y .P ro vi de a n i nc r e a s e d c a p a b i l i t y f o ru s i n g a s a t e l l i t e t o l o c a t e andde t e r m ine t h e p o s i t i o n o f s e ns o r s( b a l l o o n s , b uo ys, a i r c r a f t , s h i p sa nd f i x e d p l a t f o r m s ) a ny wh er e, f o rr e l a y t o t h e Goddard S p ac e F l i g h tC e n t e r .Measure u l t r a v i o l e t r a d i a t i o n f l u xf rom t h e Sun i n f i v e r e l a t i v e l y b r oa db an ds . F l ux v a r i a t i o n s a re r e l a t i v e .

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Image Dis sec tor Camera Record d a y t i m e c loud c ove r pho to s( I D C ) o f t h e e n t i r e E a rt h , w i t h a r e s o l u t i o nof one m i l e , f o r r e a d ou t a t Goddardf o r s up po r t o f t h e o t h e r ex p e r im e n t s."Live" photos w i l l b e r e l a ye d t o moret h a n 400 smal l g r o u n d s t a t i o n s o na l l s e ve n c o n t i n e n t s .

Backs ca t e r U l t r a v i o l e t Measure ozone d i s t r i b u t i o n i n t h eSpe ct ome t e r ( BUV ) a tm os phe r e , g loba l l yF i l t e r Wedge Sp ec tr om et er Measure water va po r c on t e n t and i t s(FWS 1 v e r t i c a l d i s t r i b u t i o n , g lo ba ll y.S e l e c t i ve C hoppe r Determine t h e temperat,ux-e i n t h eRadiometer ( S C R ) a tmosphere , f rom Ear thJc loud to pl e v e l t o 4 0 m i l e s h e i g h t ,T em pe ra tu re Humidi ty I n f r a - M eas ur e i n f r a r e d r a d i a t i o n fr omr k d Radiometer ( T H I R )

T r a c k ing :O r b i t

Data , c q u i s i t i o nF a c i l i t i e sAutomat ic P ic tu re Trans -m i s s i o n g r o u n d s t a t i o n s

Spacecraft Management

I n t e g r a t i o n & T e s tC o n t r a c t o r ( p l u sa t t i t u d e & c o n t r o lsys tem)

E a r t h d u r i n g b o t h d a y a nd n igh t a ndp r o v i d e a p i c t u r e o f c loud c ove r ,t h r e e d imens iona l mappings o f c loudcove r , t emp era t ure mapping of c lou ds ,l a n d an d o ce an s u r f a c e s , c i r r u s c l o u d sa nd r e l a t i v e h u mi d it y , an d t o s up pl ys u p p o r t i n g i n f o r m a t i o n f o r t h e o t h e re xpe r im e n t s .

S i x te e n s t a t i o n s o f t h e world-wide*ace Trac king and Data A c q u i s i t i o nNetworE (STADAN)F a i r ba nks , Alaska and Rosman, N . C .

More than 500, in c l ud in g more th an 80s t a t i o n s i n some 45 f o r e i g n c o u n t r i e s .Of f i ce o f Space Sc ience andA p p l i c a t i o n s NAS A Headquar te r s , andt h e Goddard Space F l igh t Cente r ,G r e e n b e l t , Md.G e n e r a l E l e c t r i c C o . , Missi le andS pa c e D iv i s ion , V a l l e y F or ge , Pa .

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Launch Vehicle :Management LaunchOpera t ions

Thorad

Agena-D

Goddard Space F l ig h t Cente r , U . S .A i r Force 6595th Aerospace TestWing, Vandenberg AF Base, undert e c h n i c a l s u p e r v i s i o n of t h e N A S AKennedy Space Center UnmannedLaunch Operat ionsMcDonnell Douglas Astronautics Co. ,Hunting ton Beach , C a l i f o r n i aLockheed Miss i l e s & Space Co.,Su n n y v a l e , C a l i f o r n i a

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NIMBUS DGRAVITY -GRADIENT BOOM(EXTENDED)

PNEUMATIC FILL PORTC OMMAN DANTENNA\

PITCH NOZZLE

DIRECTION IN ORBIT

ROLL NOZZLE

YAW NOZZLESUN SENSOF

SOLAR PADDLE AW SU N SENSORHORIZON SCANNER

CONTROLS CONNECTORINTERFACE PANEL1T ERCONNECTING TRUSSBEACON ANTENNAS (

SELECTIVE CHOPPERENSORY RINGLTER WEDGE SPECTROMETER RADIOMETERSELECTIVE CHOPPER RADIOMET S - BAND ANTENN AMONITOR OF ULTRAVIOLET

SOLAR ENERGY (MUSE) SPECTROMETER-1 NFRARED INTERFEROMETER

IMAGE DISSECTOR CAMERA INTERR OGATION RECORDINGAN D LOCA TION SYSTEM ANTENNAS - BAND ANTE NNA

BACKSCATTER ULTRAYIOLET SPECTROMETERTEMPERATURE/HUMIDITYINFRARED RADIOMETER

SATELLITE INFRARED SPECTROMETER--more-

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-19-NIMBUS RESULTS

A l l of the three Nimbus satellites, launched into orb it i n 1964, 1966, and 1969,respectively, have exceeded their objectives.

The more than 1-1/2 mil li on daytime and nighttime (infrared) photos taken bythese three spacecraft have provided meteorologists with a look at the Earth's cloudcover and surface temperatures never before possible.M e eoro ogy

Meteorologists single out th e vert ical temperature pro file measurements (orsoundings) from Nimbus-3 and the APT camera (which provides weather pictures o fthe original area to small ground stations anywhere in the world) as two of th e mostsign ifican t contributions to meteorology in the past 20 years.

Soundings taken by sa te ll ite were compared wi th data obtained from conven-tional sounding techiques (weather balloons) and the correlation between the twowas excellent. Vert ical temperature measurement by sate lli te represented a break-through i n meteorological technology. It enabled meteorologists to obtain quanti-tative data from the entire globe, rather than from conventional stations only whichare mostly located i n the temperate belt of the northern hemisphere. The temperaturepro file readings provided by Nimbus-3 were so good that the data were made avail-able by NASA to the Weather Bureau for preparing daily weather forecasts. Over3 mi ll ion temperature soundings have so far been collected.

More than 400 APT stations are now scattered around the world. In many partsof the world APT pictures are the major, and in some cases the only weather infor-mation source. A number o f pr ivate users in the United States and numerous foreigncountries have built their own receivers and facsimile machines at costs rangingfrom severaI hundred to severa thousand dollars e

Many of the world's large airports have APT pictures for commercial pilots tostudy before a flight. Pilots can see what the weather was l ik e wi th in the precedingtwelve hours, during the day or a t night, from New York to London, or San Fran-cisco to Tokyo before taking of f.

Nimbus I I demonstrated, for the first time, that infrared pictures could beread out " li ve" on simple APT ground equipment.

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Probably the most signif icant results from Nimbus sate llites have been theircontributions to providing quantita tive measurements global ly. Nimbus has shownthat sate llites can supply these dab tw ice a day from al l the world within less than3-1/2 hours. Previously these data were available from only about 20 per cento f the world, wi th delays often making sizeable quantities of data unusable.Oceanography

I t has been possible a t night under certain cloud-free conditions to detectareas of sharp temperature contrast, such as currents and upwelling, from NimbusHRlR photographs.

A study on large scale fluctuations of the Gul f Stream was based on Nimbusinfrared pictures. Under cloudless skies the northern boundary of the G u lf Streambetween Cape Hatteras and 60 degrees West ms identified by the contrasting graytones on pictures over severa Imonths.

The Gulf Stream boundary was seen on Nimbus photos in about 50 cases. Otherocean current boundaries and pronounced sea-surface temperature patterns, uchas the Falkland and Brazil Current discontinuity, the Agulhas Current and theKurohsio Current could be seen from Nimbus infrared photographs.

In one single infrared photo, oceanographers were able to trace the meanderingpath of the Gu lf Stream for 1,000 miles.Ice Pack Reconnaissance

High resolution telev ision cameras and infrared radiometers on Nimbus wereable to "photograph" an iceberg i n the Weddell Sea. This i s the first known casein which an iceberg has been photographed from'.a satel lite over the Arctic orAntarctic.

The iceberg ms an estimated 71 miles long and 20 mi l e s wide.Another series of Nimbus I I pictures showed a southward drift of an individualiceberg along the Greenland coast over a six-week period. Progress ms observed

regularly as i t followed the major East Greenland Current.Nimbus I I , regularly covering the Antarctic areas, presented possibilities

for mapping extremely remote areas where conventional techniques are a t bestdifficu t and expensive.

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Nimbus pictures of the Weddell Sea regions depict a semi-permanent coast-line that i s generally marked as a fixed feature on charts of the Antarctic Ocean.Portions of this coast have not been mapped for more than 20 years.Cartography and Geology

Information obtained by Nimbus weather satellites has provided useful datafor geographers and geologists.

The U. S. Geological Survey, after studying more than 300 Nimbus 1 picturesover the Antarctic, found that re li ef maps of the Antarctic were in slight error.

As a result, Mount Siple, a 10,000-foot high Antarctic mountain w a s reposi-tioned 45 m i l e s to the West. Nimbus I pictures o f the Kohler Range area at theAntarctic showed one group of mountains, not two as depicted on ear lier maps,

Geologists have used Nimbus photos to increase the ir knowledge of pastgeologic formations in certain areas of the world such as a river basin in Oregon,Paris Basin i n Central France and the Appalachian Mountains o f Pennsylvania.Snow Cover and Hydrology

Areas with snow cover greater than about three inches in nearly a l l cases hadreflectivities significantly higher than areas with lesser snow depths e

Nimbus I I APT pictures o f the East Coast of the United States showed a verybright Delaware-Maryland-Virginia peninsula blanketed the day before by an eight-inch snowfall. The rest of Maryland and Virginia had received only a trace to 4inches of snowfall and thus showed lesser ref lectiv ities.

Although present satellite photography cannot provide the quantitative (threedimensional) measurements of snow depth provided by a network of surface stations,i t can provide the limits o f snow cover and detailed qualitative estimates of snowdepth in the areas between reporting stations.

This information is of much importance to hydrologists in making ground w t e rrun-off estimates w d lood control forecasts.

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The FuturePolar orbiting satellites a t altitudes o f about 700 miles, such as Nimbus, are

the only apparent means for obtain ing every day on a global. basis, quanti tat iveatmospheric measurements.

To predict long-range weather conditions, meteorologists must have an adequatemodel of the atmosphere, suff ic ien tly large computers, and quanti tat ive measure-ments of the tota I atmospheric structure. The needed measurements are pressure,atmospheric temperatures, moisture content and wind veloc ity a t various altitudeson regular, periodic schedules over the entire Earth.

A t present, mathematical models that simulate the structure and circulat ion ofthe atmosphere are under development.

Scientists already have numerical methods for long-term integration of thegoverning thermo-hydrodynamical equations, lectronic computers for carrying outthe calculations, and some understanding of the physics of the heating processeswhich produce the large-scale motions.

A National Academy o f Sciences study has indicated that meteorologists maybe able to make predictions of significantly improved accuracy for major weatherpatterns as much as two weeks i n advance by using global information gathered fromsatellite and conventional meteorological observing systems.

Nimbus experiment concepts support the world weather watch program which i sdesigned to expand weather observational capabi lity and promote understanding of,and ab i li ty to predict, weather processes.

The scientific and meteorological communities of the United States and manyother countries are formulating and coordinating research directed toward placinglong-range forecasting of global weather on a sound scientific basis. This inter-nationa I endeavor i s ca I ed the G oba I Atmospheric Research Program (GARP) ,

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NIMBUS-D LAUNCH VE HICL E

The l au n ch v e h i c l e u s ed f o r t h e Nimbus-D mission i s aThorad-Agena-D rocket. T h e T hora d, o r l on g t a nk T hor , i s anup ra te d ve rs io n of th e Thrus t Augmented Thor ( T A T ) u se d i ncombinat ion w i t h an Agena second s t a g e f o r Nimbus lau nch es .The Thorad boos te r has a 5 0 p e r c e n t g r e a t e r t a n k volumetha n p r e v ious T ho rs wh ic h i n c r e a s e s e ng ine bu r n t i m e . Althoughno i n c r e as e i n t h r u s t i s r e a l i z e d , t h e main engine burn t i m e

i s i nc r e a s e d f r om a pp r ox im a te ly 146 seconds to about 223 seconds .The t h r e e s t r a p - o n s o l i d r o c k e t mo to rs u se d on t he Thorad

a r e a l s o u p r a t e d f rom t h e ones used on t h e T A T ' S . The Thorads t r a p - ons p r ov ide 6 2 , 0 0 0 l b s . of t h r u s t f o r 37 seconds . T h i scompares w i t h 54,000 l b s . f o r 27 s e c o n d s f o r t h e o ld m o to r s .The g r e a t e r p r o p e l l a n t c a p a c i t y o f t h e Thorad coupled w i t ht h e new s t rap- on s o l i d motors make i t p o s s i b l e to boos t a bou t50 pe r ce n t more pay load i n t o E a r t h o r b i t t ha n t h e o r i g i n a lTAT.The l a u n c h v e h i c l e i n c l u d i n g t h e 18.7 foot Nimbus ,shrouds t a n d s 1 0 9 . 5 f e e t h i g h . B ec ause t he s p a c e c r a f t i s des igned tot a k e m e t e o r o l o g i c a l o b s e r v a t i o n s n e a r l o c a l noon d u r i n g i t ss ou th to n o r t h p a s s o v er t h e E a r t h , t h e p o s s i b l e l a u n c h t i m e

from complex 2 o f the Wes te rn T e s t Range i s r e s t r i c t e d . Thelaunch window for A p r i l i s 3:lO A. M. E S T to 3:40 A.M. E S T .Nimbus Separation

Dur ing the approx imate ly 3 min. 32 see. between Agenae n g in e c u t o f f ( t h e s ec on d t i m e ) and s p a c e c r a f t s e p a r a t i o n t h ev e h i c l e p i t c h e s up s o t h a t i t i s a t an ang le o f about 80 de g r e e si n r e s p e c t to t h e h o r i z o n . A t T p l u s a b o u t 5 8 and a h a l fm in ut es a f t e r l i f t - o f f e x pl os iv e b o l t c u t t e r s a r e f i r e d on t h esp ac ec ra f t a da p t e r and compressed spr in gs push th e Nimbuss p a c e c r a f t away f rom t h e Agena s ta ge a t a r a t e of about 4 . 5f e e t -per-s econd .Retromaneuver and TOPO-A S e p a r a t i o n

A t two se co nd s a f t e r s e p a r a t i o n , a s impl taneous roll, yawmaneuver i s e xe c u t e d b y t h e Agena. T h i s m a e uv er r e s u l t s i n t h ef o r w a r d . The f i r s t small r e t r o e ng in e i s t he n f i r e d . T h i sl ower s t h e o r b i t o f t h e Agena i n r e l a t i o n s h i p to t h e Nimbuss a t e l l i t e .Agena f l y i n g r o ug h l y p a r a l l e l to t h e E a r t h P i t h i t s t a i l end

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A t a pp r ox im a te ly 10 4 m i n u t e s i n t o t h e f l i g h t a n e x pl o si v ep i n p u l l e r i s f i r e d f r e e in g t h e TOPO-A f rom t h e Agena andp l a c i n g i t i n o r b i t .

A s e c ond r e t r o ma neuve r p l a c e s t h e Agena i n a n o r b i t wherei t w i l l m a i n t a i n a minimum se p ar a t i on o f a t l e a s t 500 f e e t fromt h e Nimbus spa ce c r a f t f o r a p e r i o d o f a t l e a s t one y e a r .Sun-Synchronous O r b i t

A h i g h n o o n o r b i t i s i d e a l f o r weather s a t e l l i t e s becausei t pr ov ide s maximum i l l u m i na t i on f o r pho tog r a p h i c pu r pos e s ,and p i c t u r e s o f t h e E a r t h w i l l a l w a y s b e t a k e n a t t h e same l o c a lSun t imes e v e r y d a y . Night photos w i l l b e t a ke n a bou t m idn igh tl o c a l t i m e .

I n a Sun-synchronocs o r b i t , t h e p r e c e s s i o n ( e a s t w a r dd r i f t ) o f Nimbus w i l l b e about one degree d a i l y , a t t h e samer a t e a n d d i r e c t i o n as t h e E a r t h moves ar oun d th e Sun. The Sunw i l l always b e be hi nd Nimbus du ri ng d a y l i g h t o r b i t , w hichr e s u l t s i n i d e a l l i g h t i n g c o nd i t i o ns .

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- 2 7 -

TOPO-A

1. Genera l - TOPO-A i s t h e f i r s t s a t e l l i t e to b e l a unc he di n a p la nne d s e r i e s o f l a u nc h es f o r R & D i n v e s t i g a t i o n o f anew t e c hn ique f o r a c c u r a t e , r e a l t im e d e t e r m i n a t io n of p o s i t i o n son the E a r t h ' s s u r f a c e . The R & D i n v e s t i g a t i o n s w i l l u t i l i z emodi f ied g round t r ac k in g equipment and space c r a f t componentsf rom the A r m y ' s Geode t ic SECOR Program which i s c u r r e n t l ybe ing pha s e d out o f o p e r a t i o n a l u s e. S E C O R i s an acronym f o r-Equ ent ia l COll a t io n o f Range. The A r m y Ge ode t i c SECOR Program,through t h e u s e o f e l e c t r o n i c r a n gi n g to t h e o r b i t i n g s p a c e c r a f t ,p e r m i t t e d t h e e x t e n s i o n o f g e o d e t i c c o n t r o l a r ou nd t h e c ir cu m-f e r e n c e o f t h e E a r th t hus im pr oving knowledge o f t h e s i z e a ndshape o f t h e E a r t h f o r us e i n t h e A r m y ' s mapping program.

Although t h e b a s i c t e ch n iq u e u t i l i z e d i n t h e new R & Dprogram w i l l s t i l l b e e l e c t r o n i c r an g in g , t h e m o d i fi c a ti o n sw i l l e n a b l e a l l r a n g i n g i n f o r m a t i o n to be accumulated a t as i n g l e g round t r a c k i n g s t a t i o n to e n a b l e e x pe d i t e d p o s i t i o ncomputa t ion. T h i s w i l l b e accomplished b y i n c o r p o r a t i n g ar a n g e d a t a r e l a y c a p a b i l i t y i n t o t h e s y s t e m .2 . TOPO-A S p a c e c r a f t D e s c r i p t i o n

TOPO-A i-s n o t an acronym; it m e r e l y i d e n t i f i e s t h e f i r s ts a t e l l i t e i n a new s e r i e s to b e l a unc he d f o r t h e U.S. A r m yTopographic Command (TOPOCOM). TOPOCOM, under t h e O f f i c e o ft h e C h i e f of Enginee r s (OCE), has t e c h n i c a l c og ni za nc e o f t h eR & D program.

TOPO-A i s r e c t a n g u l a r i n s ha pe w i t h t h e d i m e n s i o n s 1 4 x 1 2 ~ 9i n c h e s . The e x t e r i o r o f t h e s p a c e c r a f t i s a l m o s t e n t i r e l ycovered b y s o l a r c e l l s which r e ch a r ge t h e main b a t t e r y powersupply o f t h e s p a c e c r a f t . I n a d d i t i o n to t h e b a t t e r i e s , t h es p a c e c r a f t c o n ta i n s a r a n g i n g t r a n s p o n d e r a n d a t e l e m e t r yt r a n s m i t t e r . The a n t e n n a s y s t e m c o n s i s t s o f f l e x i b l e meta lt a p e s which f o l d a round t h e s p a c e c r a f t d u r i n g l a u nc h . Thet o t a l we ig ht o f TOPO-A i s 40 pounds.TOPO-A w i l l b e p l a c e d i n a c i r c u l a r o r b i t a t a bou t 6 7 5m i l e s .

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-2 8-NIMBUS-D PROJECT OFFICIALS

NASA H e a d a u a r t e r s . Was hing tonD r . John E . Naugle

D r . John M . DeNoyer

A s s o c i a t e A d m i n i s t r a t o r , O f f i c eo f S pa ce S c i e nc e and App l i c a t i o nsD i r e c t o r , E a r t h O b se r v at i o n sPrograms

Bru ton B . S ch ar d t Nimbus Program ManagerJ os e ph B . Mahon D i re ct o r , Launch Ve hi cl e andPropuls ion ProgramsR . W . Ma nv il le Thor/Agena Program ManagerGoddard Space F l igh t Cente rD r . John F . C l a r k D i r e c t o rH a r r y P r e s s Nimbus P r o j e c t ManagerSt an le y Weiland Obse rva tory Systems ManagerDr. W i l l i a m Nordberg Nimbus P r o j ec t S c i e n t i s tW i l l i a m R . Sc hi nd le r Launch Ve hi c l es Sys tems ManagerKennedy Space Ce nte r , F l o r i d aRober t H . Gray Director, Unmanned LaunchO p e r a t i o n sH . R . VanGoey Manager, WTR O p e r a t i o n sW . S . Ca r tw r ig ht Manager , Agena Op era t io ns , WTR

U.S. Army Corps of EngineersRi ch ar d Malone Launch Manager, TOPO-AG e ne r al E l e c t r i c Co.L e w i s T . Seaman GE Nimbus Program Manager,Miss i l e and Space Di v i s i on

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McDonnell Douglas Corp.W. L . Duval

Lockheed Miss i les & Space Co.Ray Gavlak

V ic e P r e s i d e n t , D i r e c t o r ,Vandenberg T e s t C en t e rHuntington Beach, C a l i f .

Re sid ent Manager, Space SystemsVandenberg A i r Force Base,C a l i f .

NIMBUS-D EXPERIMENTERSD r . Rudolph A . HanelD r . Barney J . ConrathGoddard Space Fl igh t CenterGr ee nbe l t , Md.D r . Donald F . HeathGoddard Space F l i g h t Ce nter

D r . Warren A . HovisD r . David Q . WarkDonald Hi l l ea ryEnv i ronmen ta l Sc ienceS e r v i c e s A d m i n i s t r a t i o nC h a r l e s E . CoteGoddard Space F l i g h t CenterAndrew W . McCullockGoddard Space F l i g h t Cen te rGera ld L . B u r d e t tGoddard Space Fl igh t CenterD r . J . T . HoughtonClarendon Labora to ryOxford, England; andD r . S . D . SmithJ . J . Thomson PhysicalLabora to ry , Read ing ,England

I n f r a r e d I n t e r f e r om e t e rS p ec t r o m e t e r (IRIS)

B ac k s c a t t e r U l t r av i o l e t (BUV)a nd M o ni to r U l t r a v i o l e t S o l a rEnergy (MUSE)F i l t e r Wedge Spe ct ro mete r (FWS)S a t e l l i t e I n f r a r e d S pe ct ro me te r(SIRS)

I n t e r r o g a t i o n R e c o r d i n g a n dLocat ion System (IRLS)Temperature , Humidi ty Inf raredRadiometer (THIR)Image Di r e c t o r Camera Subsystem( IDCS )Se le c t iv e Chopper Rad iomete r( SCR)

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- 30 -SPACECRAFT CONTRACTORS

CompanyAdcole Corp.Waltham, Mass.Beckman InstrumentLos Angeles, Calif.California ComputerLos Angeles, Calif.Products

Elliott Brothers Ltd.London, EnglandEnvironmental ScienceRockville, Md.Services Administration

General Electric Co.Space Systems OrganizationValley Forge, Pa.

International Telephone &Industrial Lab or t r eFt. Wayne, Ind.Telegraph

Radiation Inc.Melbourne, Fla.

Radio Corporation ofAstro Electronics DivisionPrinceton, N. J.America

Santa Barbara ResearchHughes Aircraft Co.Santa Barbara, Calif.Center, Subsidiary of

Sperry GyroscopeGreat Neck, N.Y.Texas Instruments, Inc.Dallas, Tex.

SubsystemMonitor of UltrEnergy (MUSE) violet Solar

Backscatter Ultraviolet (BUV)ExperimentCommand Clock

Selective Chopper Radiometer(SCR)

Satellite Infrared Spectrometer(SIRS)

Nimbus D Integration and Test,Stabilization and Control Sub-system Integration, SpacecraftStructure and AntennasFilter Wedge Spectrometer (FWS)and Image Dissector CameraSystem (IDCS)

Versatile Information Processor,(VIP), or housekeeping telemetry,and the Interrogation Recordingand Location System (IRLS)High Data Rate Storage System,Command Receivers, Solar PowerSystem and the Direct ReadoutInfrared TransmitterTemperature Humidity InfraredRadiometer (THIR)

Rate Measuring Package

Infrared Interferometer Spectro-meter (IRIS)-more-


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Major Ground Equipment Contractors

CompanyAdler/WestrexCommunications DivisionNew Rochelle, N.Y.of Litton Systems,Inc.

Allied Research AssociatesConcord, Mass.Inc.

California ComputerLos Angeles, Calif.Products

Control Data Corp.Minneapolis, Minn.General Electric Co.Space Systems OrganizationValley Forge, Pa.Lear Siegler, Inc.Anaheim, Calif.

RCA Service Co.Cherry Hill, N.J.

Launch Vehicle ContractorsCompanyBell Aerosystems Co.Buffalo, N.Y.Douglas Aircraft Co.Missiles & Space SystemsSanta Monica, Calif.Division

ElectrosolidsLos Angeles, Calif.

ResponsibilityTemperature Humidity InfraredRadiometer (THIR) FacsimileEquipment

Operate the Nimbus Data Utiliza-tion Center

Ground Station Command Console

Ground Stati In Computers

Operate the Nimbus ControlCenter

Computer System for DecomputatingVersatile Information Processor(VIP) Telemetry Data

Operate the Nimbus Data HandlingSystem at Goddard Space FlightCenter and Alaska

ResponsibilityAgena D Engine

Thorad (Long Tank T h o r )

Thor Autopilot

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ResponsibilityTexas Instruments, Inc.Dallas, Tex.Lockheed Missiles & Spaceco.Division of LockheedAircraft Co.Sunnyvale, Calif.Rocketdyne, Inc.Division of North AmericanRockwell, Inc.Canoga Park, Calif.Thiokol Chemical Corp.Huntsville, Ala.Western Electric Co.Burlington, N . C .

Thor Autopilot

Agena D Vehicle (Airframe andAssociated Electronics)

Thorad Engine

Solid Propellant Strap-onBoostersThorad Guidance Systems

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nimbus-d - press kit

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