GEOS-C (GEOS 3) Press Kit

8/7/2019 GEOS-C (GEOS 3) Press Kit

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NATIONAL AERONAUTICS AN DSPACE ADMINISTRATIONW a l l o p Flight CenterWallops Island, Va 23337P ho ne: 8 0 4 /8 2 4 - 3 4 1 1 Ext. 5 7 9

F O R R E L E A S E :?a Howard Allaway

Headquarters, Washington, D. C.(Phone: 202/755-8617)MONDAY,March 31, 1975

Joyce B. M i l l i n e rWal lops Fl ight Center(Phone: 804/824-3411 x579)

Rel ea se No. 75-4

NEW SATELLITE TO MEASURE OCEAN SURFACE TOPOGRAPHY AND SE A STATE

An Ear th -o rb i t in g sp ace c r a f t des igned t o measure p r ec i se ly t hetopography of the ocean su rf ac e and the sea s t a t e - -wave he igh t ,pe r iod , and d i re c t i on - - i s be ing p repa red by NASA for launch noe a r l i e r t h a n A p r i l 9.

The new oceanographic-geodetic s a t e l l i t e , designated Geody--7namics Experimental Ocean S a t e l l i t h e t h i r d i n a

ser ies of sp ace c ra f t des igned t o of Ea r th ' s shapeand dynamic behavior.

The 340-ki logram (750-pound) s a t e l l i t e w i l l be launched a-board a Delta ro ck et from the Western T e s t Range near Lompoc,


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- 2 -C a l i f o r n i a , i n t o a c i r c u l a r o r b i t a t a n a l t i t u d e o f 843 ki lomete rs(523 s t a t u t e mi les ) where i t w i l l c i r c l e E a r t h e v er y 1 01 .8 a i n u t e son a pa th in c l in ed 65 de gre e s r e t rog ra de to the e qua to r .

GEOS-C w i l l be used t o compare se ve ra l new and est ab li sh ed geo-phy sica l measuring s y s tems inc luding a r a d a r a l t ime te r and s a t e l l i t e -t o - s a t e l l i t e t r a c k i n g as w e l l as r a d a r , l a s e r , and dopple r t r ack ing .

The spacecraft w i l l d em on st ra te t h e f e a s i b i l i t y and t h e u t i l i t yof s a t e l l i t e a l t im e te r s fo r measuring th e geometry of th e oceansand mapping the topography of the ocean surface t o w i t hi n a pre -c i s i o n t o 1 t o 2 meters (about 40 t o 80 inches) .be beamed t o th e ocean su rf ac e from the s a t e l l i t e and t h e i r r e t u r nt imed t o pre c i se ly measure the s a t e l l i t e a l t i t u d e from t h e sea s u r -f a c e , thus providing mean sea l e ve l de te rm ina t ions - - im por tan t i n thed e te r mi n at i on of E a r t h 's g r a v i t y f i e l d and i n t h e d e t e c t i o n o f g l o b a lo ce an c i r c u l a t i o n p a t t e r n s , The g e n e r a l s ha pe o r c h a r a c t e r i s t i c s oft he r e tu rne d pu l se s as r e f l e c t e d f rom the sea s u r f a c e w i l l providea measure of the sea s t a t e i n the areas surveyed-- important i n de-t e c t ing rough sea c o n di t io n s o r t h e e f f e c t o f s t or ms .

Radar pulses w i l l

The a l t i me t e r d a t a a r e e xp ec te d t o c o n t r i b u t e t o t h e r e f in e m en tof pre se nt knowledge of t he geoid --th at i s , t he l e ve l t ha t would beassumed by t he ocean sur fac e i n the absence of winds, cu rr en ts , andt i d e s . They w i l l a l s o p ro v id e a de s c r ip t io n o f the be ha v io r of the

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- 3 -ocean 's sur face t h a t v a r ie s wi th t ime due t o cur r en ts and winds .Thus t h e r a d a r a l t i m e t e r w i l l c on t r ib u te t o t e c hno logy l e a ding t oh ig h ly a c cu r at e o p e ra t io n a l s a t e l l i t e al t i m e tr y .

The orbit of GEOS-C must be a c c u r at e l y known s o t h a t t h eheight above sea l e ve l measured by th e a l t i m e t e r can be accur a te l yc a l i b r a t e d . To do t h i s , GEOS-C w i l l be t rac ke d from th e ground byl a s e r , ra di o dopp ler , C-band ra da r , and S-band rad ar , as w e l l asbeing t racked by Applica t ions Technology Sate l l i te06 (ATS-6) ,launched l a s t yea r , thus making GEOS-C t h e b e s t t ra ck ed s p a c e c r a f tever launched by NASA.

I n a d d i t i o n t o alt imeter c a l i b r a t i o n , t h e p r e c i s i o n tr a ck i n gw i l l y i e l d improved g r a v i t y f i e ld in fwm a t ion and w i l l make possiblem ore p r e c i se pos i t ion loc a t ion of ground t rack in g s t a t io ns Thisd a t a w i l l be us e f u l i n such s tu d i es of Ear th dynamics as t e c t o n i cp l a t e m ot ion, Ea r th ro ta t i on , po la r mo tion , and c on t in e n t a l d r i f ttheory.

The s a t e l l i t e - t o - s a t e l l i t e t r a ck i n g e xp er im en t by GEOS-C andATS-6, t h e f i r s t of t h i s k in d, i s expected t o provide more pre ci seo r b i t i nf or ma ti o n on t h e o bs er ve d s a t e l l i t e th an i s now obtain-a b le by the l e s s c ons ta n t obse rva t ions o f g round s t a t io ns .

From i t s geosynchronous a l t i tude , ATS-6 can observe GEOS-C f o rmore th an h a l f i t s orbit. ATS-6 w i l l t r a c k a nd GEOS-C w i l l r a d i o

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r a ng ing s igna l s th rough i t s S-band tr an sp on de r t o ATS-6, which i nt u r n w i l l r e l a y t h e d a t a t o g rau nd s t a t i o n s .

GEOS-C w i l l c a r ry an a r r a y o f qu a r tz r e f l e c t o r s f o r l a s e r rang-ing . The r i n g o f r e f l e c t o r s a ro un d t h e s a t e l l i t e h a s been de si gn edt o permit measurements t o acc ura cie s of 10 cent i mete rs (4 inch es) ,which h a s n o t b een p o s s i b l e i n l a s e r t r ac k i n g o f p re v io u s s a t e l l i t e s .A l a se r beam w i l l be s e n t t o t h e s a t e l l i t e and t h e r e f l e c t e d s i g n a lrece ived a t t h e same ground s i t e . A network of ground l a s e r rangings t a t i o n s w i l l be us ed t o t r a c k GEOS-C dur ing i t s m i s s i o n l i f e t i m e .

Powered by pane ls of s o l a r c e l l s , t he 1 3 2 cent imete r (5 2 i nc h )diameter GEOS-C w i l l be f ix e d i n o r b i t wi th i t s antennas poin tedEarthward by means of an extremely p r e c i s e g r a vi t y- g r ad i e nt s t a b i l i -z a t i o n s y s t e m employing a scissors-type boom with a 45-kilogram (100-pound) end mass. The mass a t the end o f the boom swings outward ast h e s p a ce c r a ft c i r c l e s t h e g l ob e i n i t s f ix e d o r b i t a l p a th , l i k e ab a l l t w i r l ed on a s t r in g , kee ping th e an te nna s a t the oppos i te endaimed always a t Earth. A momentum wh ee l, l i k e a gyroscope, augmentst h e g r a v i t y g r a d i e n t boom t o p r o vi d e f u l l t h re e -a x i s s t a b i l i z a t i o n .

The GEOS-C i s cons ide red a br id gi ng s t e p between t he NGSP andthe emerging NASA Earth and Ocean Physics Applications Program.

The GEOS-C Program i s under the management of N A S A ' s Off ice ofApplica t ions. The NASA Wallops F li g h t Cent er has p ro je ct management

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- 5 -r e s p o n s i b i l i t y f o r GEOS-C.NASA Goddard Space F l i g h t Cent er, which al s o manages t h e Deltal a u n c h v e h i c l e p r o j e c t ,by th e Applied Physics Laboratory of th e Johns Hopkins Uni ver sit y.Launch s i t e opera t ion s are managed by the NASA Kennedy Space CenterUnmanned Launch Operations Directorate.

Mission o pe rat io ns a r e managed by t he

The spacecraf t was des igned and fabr ica ted

The GEOS-C spa c e c ra f t and in s trum en t s c o s t a bout $ 1 2 . 5 m i l l i o n ;the De l ta launch veh ic l e , about $4.5 m i l l i o n .

(END OF GENERAL RELEASE: BACKGROUND INFORMATION FOLLOWS.)

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- 6 -BACKGROUND

Since th e advent of s a t e l l i t e s , man has made much progr ess i nre f i n i ng h i s knowledge of th e s i z e and shape of Earth . The secondU. S. s a t e l l i t e (Vanguard 1, March 1 7 , 1958) determined the famouspear-shaped component of Earth during the In t e rn a t i o n a l Geo p h y s i ca lYear (IGY).

T h e p a r t i c u l a r o b j e c t i v e s of the NASA program i n s a t e l l i t e geod-e s y have been t o provide a pre c i s e measurement o f E ar th ' s su r fac eand a m ath em a ti ca l d e s c r ip t i o n o f Ea r th ' s s u r face an d i t s g r a v i t y f i e l d .These obje ct iv es formed th e ba s i s of the Nat io nal Geodet ic S a t e l l i t eProgram (NGSP) i n i t i a t e d i n 1964 , Under NASA management, the NGSPwas a j o i n t vent ur e of th e Departments of Defense and Commerce, wi thp a r t i c i p a t i o n by s e v e r a l u n i v e r s i t i e s and i n t e r n a t i o n a l o r ga n i za t io n s ,t o meet some of th e geod et ic needs of th e U. S .

The f i r s t o b j e c t iv e o f t h e Ge od et ic S a t e l l i t e Program w a s t o g en -era te a unif ied world survey network wi th an accuracy of 10 meters.Such a un i f ie d wor ld su rvey network p rov ides necessary po in t s f o rg eo p h y s i c i s t s t o o b t a i n a b as i c r e f e ren ce fo r t h e p h y s i ca l meas ure-ments of Earth. These common reference points have been a very i m -po rt an t co nt r ib ut io n of the space program. One of the f i r s t accom-p l is h m en t s i n s p ace i n 1959 w a s t h e g en e ra t i o n o f a Mercury datumused as a ba si s fo r the Mercury t ra cki ng network .The second objective of the NGSP w a s to deve lope a more precise

I t a l s o h asmath emat ical model of E ar th ' s g r a v i t a t i o n a l f i e l d . This in fo rmat ionrev ea l ed d e t a i l s abo u t Ea r t h ' s dynam ics an d s t r u c tu re .had s i g n i f i c a n t s pa c e a p p l i c a t i o n i n im pro ving o r b i t a l p r e d i c t i o nca p a b i l i t y and made p o s s ib l e m i ss ion s t h a t r eq u i r e h ig h -p rec i s io np o s i t i o n d e t e rm in a t i o n .The following i s a b r i e f f l i g h t h i s t o r y of t he NASA s a t e l l i t egeodesy program:

-- Expl orer- 22 (Beacon Expl orer- B), launched October 10, 1964.I n a d d i t i o n t o i on o sp h er ic s t u d i e s , t h i s s a t e l l i t e providedth e f i r s t i n s t a n ce o f grou nd -b as ed l a s e r t r ac k i ng f o r u se i nt r ack in g an d g eo d e t i c s t u d i e s .

-- Explorer-27 (Beacon Exp lorer- C), launched A p ri l 29, 1965.With g eo d e t i c o b j ec t i v e s p r im ary , t h i s m i s s io n ca r r i ed u l t r a -s t a b l e o s c i l l a t o r s f o r p r e c i s e Doppler t r a c k in g of o r b i t a li r r e g u l a r i t i e s f o r g r a v i t y f i e l d de te rm in at io n. Las e r t r ack in g- more -


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- 7 -exper iments and i onos pher i c s tu d ie s were cont inued.

-- G E O S - 1 (Ex plo rer- 29) , launc hed November 6, 1965. This mis sio nc o nt ai n ed b a s i c i n s t r u m e nt a t i o n from s e v e r a l p a r t i c i p a t i n gagenc ies : a U. S. Navy Doppler system, U. S. Army e l e c t r o n i cranging system (SECOR), U . S. A i r Force op t i ca l beacons, andNASA l aser re f l ec to rs and range and ran ge- ra te system. Thiscombination of instru ments accomplished two important ob je ct -i v e s : (1) most o f t he obse rva t ion c a pa b i l i t y of t h e U. s .c ou ld be focused on one s a t e l l i t e ; and (2 ) e r ro r s i n a par -t i c u l a r sys tem could be d iscovered and cor rec ted by re fe renc eto o the r sys t e m s .

-- PAGEOS -1 (PAssive GEOS), launch ed Ju l y 1, 1966. This mis sio ncons is ted of th e use of an ECHO-1 type, aluminized M y l a r b a l -l oo n f o r o p t i c a l s i g h t i n g by su n l i g h t r e f l e c t e d fm m t h e s a t -e l l i t e .s t a t i o n s d et er mi ne d t h e i r o r i e n t a t i o n t o one a no t h er .

By observing PAGEOS-1 a g a i n s t t h e s t a r background,

-- GEOS-2 (Explorer 36), launched January 11, 1968. This mis sio nw a s n e a rl y i d e n t i c a l t o GEOS-1 w i t h a d d i t i o n a l laser equipmentand a new radar system.- - Skylab, launched May 14, 1973. This manned o rb i t in g la bo ra t or yw a s equipped w i t h an Ea rt h Resources Expe rimen t Package (EREP)t h a t i nc lu de d an e a r l i e r v e r s i o n of t h e GEOS-C r a d a r a l t i m e t e r .The da ta obta ined from th e a l t i m et er provided "proof of concept"f o r t h e GEOS-C instrument and supplie d l oc al iz ed samples of sea

surface topography da ta .I n a d d i t i o n t o t h e d a t a from t he s e s a t e l l i t e s , c o ns id er ab le i n -formation has been acquired from many oth er s a t e l l i t e s whose o r b i tc h a r a c t e r i s t i c s a n d s y s e m s have cont r ibu ted t o s o l u t i o n s i n g eo de sy .

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- 8 -PROJECT DESCRIPTION

The purpose of the GEOS-C P r o j e c t i s t o des ign , deve lop , andlaunch a n oce a nograph ic/ge ode t ic s a t e l l i t e a nd t o pe rform e xpe ri -ments i n suppor t o f the NASA Earth and Ocean Physics ApplicationsProgram (EOPAP). The GEOS-C P r o j e c t w i l l a p pl y s a t e l l i t e t e ch ni qu est o geosc ience inves t iga t ions- -oceanography and so l id -Ear th phys ics --t o :

1. D em onstrate t h e f e a s i b i l i t y and u t i l i t y of s a t e l l i t e a l t i -meters f o r measuring th e geometry of t he ocean sur face . With suf -f i c i e n t a cc u ra cy i n t h e d e te r m in a ti o n o f t h e g e o c en t r i c p o s i t i o n o fthe spa c e c ra f t and wi th su i t a b l e a l t i m e t ry , t he ge om et ry o f th eocean sur fac e can be desc r ibed and sea le ve l de te rmina t ions can bemade. This , i n tu rn w i l l c on t r ibu t e t o re f ine m en t o f the p r e se n tknowledge of t he geo id ( t h a t i s , th e l e v e l t h a t would be assumed bythe oce an su r f a c e i n the a bse nce of w inds , c u r r e n t s , a nd t id e s ) andt o t h e i n i t i a l d e s c r i p t i o n o f t h e t im e- va ry in g b e h a v io r o f t h eoc e a n 's su r f a c e and the l a rg e r qua s i - s t e ady s t a t e depar tures ofthe se a su r f a c e from the ge o id - -se a su r f a c e s lope s , t i d e s , geo -lo g i c a l e f f e c t s on the oc e a n 's su r f a c e , e t c . The m is s ion w i l l pro-vide da ta f o r th e d et ec t i on and measurement of oceanographic fea-tures such as se a s t a t e , wave heights , and major current s y s t em s .

2 . C o n tr i bu t e t o t h e c a l i b r a t i o n , d a t a a c cu ra cy d e te r m in a t io n ,and improvement of c andi date ground-based and s a t e l l i te -b or n etr ac ki ng systems. The improvement i n ground tr ac ki ng accuracy ,e s p e c i a l l y t h e l a s e r t r a c k i n g , c ou pl ed w i t h t he a l t i m e t e r d a t aw i l l c on t r ibu t e t o the so l u t i on o f such prob lem s as d e t e c t i o n andmeasurement of l o c a l gr av i t y anomalies and the temporal v ar ia t i o nof t h e g r a v i t y f i e l d ; t h e v e r i f i c a t i o n o f c o n t in e n t a l d r i f t t he or y,po la r motion , te c t on ic mot ions (changes i n the s t ru c t u re of E a r t h ' sc r u s t ) , f a u l t m o tions , a nd Ea rth ro ta t ion .

3 . Compare and co rr e l a t e r e s u l t s o bta in ed and make ava i l ab lebo th the obse rva t iona l da t a and the r e su l t s o f a na lyse s .The GEOS-C m i ss io n a c t i v i t i e s a r e p r e s e n t ly s ch ed ul ed f o r a p-proximate ly a one-year pe r iod , a l though the a l t i m e t e r and sea -sur -f ac e t opography f e a s i b i l i t y o b j e ct i v e s c a n b e s a t i s f i e d i n ab ou ts i x months. Data w i l l be provided t o re f i ne the geo de t ic and geo-p h y s i c a l r e s u l t s of th e Nati onal G eodet ic S a t e l l i t e Program (NGSP)and furnish a t e s t bed f o r new systems and techniq ues t h a t a re ex-pec ted t o c o n t r i b u t e h e a v i l y toward t h e o b j e c t i v e s o f EOPAP andpa r t i c u la r ly to the de ve lopm e n t o f SEASAT, a new oceanographics a t e l l i t e b ei n g p la nn ed f o r la un ch i n 1978. This mission w i l l a l s ocon t r ib u te t o f u l f i l l i n g the Department of Defense C-band radar

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c a l i b r a t io n r equ ir em e nt s a nd the a l t i me t e r requirements o f both th eDepartments of Defense and Commerce.A broad spectrum of oceanographic and sc ie nc e and engineer inginformation w i l l r e su l t from the a na l ys i s o f d a t a obta ine d f romGEOS-C. For example, 41 i n v e s t i g a t o r s o r in ve s t ig a t in g teams f rom

governm en t, un i ve r s i t y , and in du s t r i a l o rga n iz a t ions were se l e c te dfrom proposals submit ted i n response t o a c a l l f o r space f l i g h td a t a i n v e s t i g a t i o n s i s s u e d i n O cto be r 1 9 7 2 . A na ly si s of t h e f i r s tquick-look data w i l l b e g in ab ou t two weeks a f t e r t h e s a t e l l i t e h asbeen tu rne d on i n o r b i t , and arran geme nts have been made t o pro videa p p r o p r i a t e data t o e ac h i n v e s t i g a t o r on a r o u t i n e b a s i s .

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- 10 -M I S S I O N O B J E C T I V E S

The GEOS-C m i ss io n o b j e c t iv e s i n o rd e r o f p r i o r i t y a t laun cha r e :

1. To p erf or m a n i n - o r b i t s a t e l l i t e a l t i m e t e r ex pe ri me nt t o :( a) d et er mi ne th e f e a s i b i l i t y and u t i l i t y o f a space-borne radara l t i m et er t o map th e topography of the ocean sur fa ce with an abso-l u t e accuracy of p lus o r minus 5 met ers , (16% fe e0 and wi th ar e l a t i v e a c c u r a c y o f 1 t o 2 meters (40 t o 80 inche s) , (b) de te rminet h e f e a s i b i l i t y of measu ring t h e d e f l e c t i o n o f t h e v e r t i c a l a t sea,(c ) de termine the f e a s i b i l i t y of measuring wave he i gh t , and (d) con-t r i b u t e t o t h e te ch no lo gy o f f u t u r e a l t i m e t e r - s a t e l l i t e sys tems witha 10-cent imeter (4- inch) measurement capabil i ty .2 . To suppor t f u r t he r the c a l i b r a t i on o f NASA and other agen-c i e s ' ground C-band r ad ar systems by prov idi ng a spaceborne coh eren tC-band transponder sys t em, t o a s s i s t i n l o c a t in g t h e se s t a t i o n s i nthe un i f ied Ear th-cente red re fe renc e sys tem, and t o provide t rack ingcoverage i n suppor t o f the rada r -a l t im e te r exper iment.3 . To perform a s a t e l l i t e - t o - s a t e l l i t e t r ac k in g ex per im en t w i thth e Ap pli cat ion s Technology S a t e l l i t e - 6 (ATS-6) us ing an S-bandt r a nsponde r sys te m t o d i r e c t ly measu re the sh o r t pe r iod a c c e le r a t i onsim pa rt ed t o the spa c e c ra f t by the g r a v i t y f i e l d and t o determ ine thep o s i t i o n o f t h e s p a c e cr a f t . The s a t e l l i t e - t o - s a t e l l i t e t r ac k in g

s y s t e m w i l l a l s o be used fo r re lay in g a l t ime te r - da t a th rough ATS-6.4. To suppor t fu r t he r the in te rcompar ison of new and establishedgeod e t ic and geophys ica l measuring sys tems, inc luding the rad ar a l -t ime te r , s a t e l l i t e - t o - s a t e l l i t e t r a c k ing , and C-band, S -band, l a s e r ,and dopple r t r ack ing s y s t em s .5. T o in v es ti g at e so lid -E ar th dynamic phenomena such as p o l a rm ot ion, f a u l t m ot ion, Ea r th ro ta t i on , Ea r th t i de s , a nd c on t i ne n ta ld r i f t t he or y w it h p re c is i o n s a t e l l i t e t r a ck i ng sys tems such as t h el a s e r and doppler s y s e m s .6. To re f i n e fu r t he r orb i t -de te rm ina t io n techniques , the determ-

ina t io n of in t e rda tum t i e s , and g ra v i t y models wit h a s p a c e c r a f tequipped with l a s e r re t rore f lec tors , C-band t ranponders , S -bandtransp onde rs , and doppl er beacons.7. To s u p po r t t h e c a l i b r a t i o n o f t h e S-Band s i t e s i n t h e N A S A ' sSpace Tracking and Data Network (STDN) by furnishing a space-borneS-Band transponder to a s s i s t i n p o s i t i o n i n g t h e n etw ork s t a t i o n s i n

the world re fe renc e t rack in g s y s t e m , and t o a s s i s t i n e v al u a ti n g t h e- more -


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- 11 -Unified S-Band system as a tool for geodesy and precision orbitdetermination.

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- 1 2 -SPACECRAFT

GEOS-C i s a dens ely packed, 340-ki logram (750-pound) s a t e l l i t ewit h an ei gh t-s id ed aluminum s h e l l topped by a tr un cat ed pyramid.I t i s 132 cent im eters (53 inche s) wide and 81 cent im eters (32 i n -ches) h igh .which w a s launched January 11, 1968 , w i th the su bs t i tu t i on o fheavi e r t r us se s t o accommodate t he ad di t i on a l we ight .I t s s t r u c t u r e i s b a s i c a l l y t h e same as t h a t o f G E O S - 2 ,

G E O S - C ' s main purpose i s t o pe rform exper iments i n suppor t o ft h e a p p l i c a t i o n of g e o d et i c s a t e l l i t e t e ch n iq u es t o g eo s ci e n ce s ,i . e . , s o l i d Ear th phys ics and oceanography. The exper iments GEOS-Cc a r r i e s t o a ch ie ve i t s o b j e c t i v e s a re :- - A r a d a r a l t i m e t e r - - t h e f i r s t t o be c a r r i e d on an unmanneds p a c e c ra f t - -t o d em on st ra te th e f e a s i b i l i t y and u t i l i t y o f us in g a non-board a l t im e t e r t o de te c t and measure oceanographic fea tu res

such as se a s t a t e , wave heights, and major current systems.- - Two C-band transponders t o supp or t the a l t im et er and C-bandsys tem c a l i b r a t i o n as w e l l as f o r e xpe rim e n ta tion t o de te rm ine theaccuracy of the system f o r geometr ic and gravim etr i c geodesy inves-t i g a t i o n s .-- One S-band t ra nsponder f o r s a t e l l i t e - t o - s a t e l l i t e t r a c k ingand f o r Earth t rackin g exper iments t o measure more pre ci se ly th es a t e l l i t e o r b i t and t h e g r a v i ty f i e l d .- - L as er r e t r o r e f l e c t o r s f o r measuring t h e s a t e l l i t e r an ge a to p t i c a l f r e q u e n c i e s .- - A rad io dopple r sys tem t h a t t r ansmi ts on two coherent f re -q ue nc ie s u se d t o o b t ai n p r e c is i o n s a t e l l i t e r an ge r a t e d a t a .

The r a d a r a l t i m e t e r , l a s e r r e t r o r e f l e c t o r s , and t h e v a ri ou santennas a re mounted on a p la t fo rm a t t he Ea r th - f a cing end o f thes a t e l l i t e .The s p a c e c r a f t ' s o u t e r s u r f a ce s c a r r i e d p an e ls o f s o l a r c e l l s .

The s o l a r c e l l a r r a y s a r e designed t o prov ide maximum s o l a r c e l lpower outp ut and minimum d a i l y average f l uc tu at io ns i n the s a t e l -l i t e ' s e xp os ur e t o s u n l i g h t a s i t o r b i t s E a r t h .t i t u d e s e n s o r s a r e mounted below th ree eq ua to r ia l s o la r c e l l pane ls .These se n so r s pr ov id e i n fo r m at i on on t h e s a t e l l i t e ' s o r i e n t a t i o nr e l a t i v e t o t h e Sun.

D i g i t a l s o l a r a t -

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- 13 -The C-band and S-band t ransponders and the d o p p l e r system aremounted i n t he s a t e l l i t e . Also i nc lu de d i n t he s a t e l l i t e a r e t h ecommand system, th e telemetry system, and t h e b a t t e r y which i s wiredt o t he s o l a r c e l l ar ra y . A thr ee- axi s vec tor magnetometer f or meas-

u ri ng t h e s a t e l l i t e o r i e n t a t io n with r e s p e c t t o Ea r th ' s m agn eti cf i e l d and an e lect romagnet for s t a b i l i z i n g t h e s a t e l l i t e magnet ica l lya r e a l s o mounted i n t h e s a t e l l i t e .

A 600-centimeter s c i s s o r typ e boom extends from a housing i n thepyramid end o f the s p a c e c r a f t t o p ro vi de g r a v i t y g r a d i e n t s t a b i l i z a t i o nof the s a t e l l i t e a f t e r i t i s m a g n e t i c a l l y s t a b i l i z e d , s o t h a t t h e a l -t i m e t e r , antennas, and laser r e f l e c t o r s w i l l poi nt Earthward a t a l ltimes. The boom can be r e t r a c t e d o r extended t o d i f f e r e n t l e n g t h s bymeans o f a m otor l o ca t ed i n s id e t h e s a t e l l i t e . A l s o i n the s a t e l l i t ei s a c ons tan t-sp eed momentum wheel which provid es f u l l th re e- ax iss t a b i l i z a t i o n .

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- 14 -INVES TIGATIONS

The GEOS-C miss ion w i l l c onduc t inve s t iga t i ons i n 13 s p e c i f i cc a t e g o r i e s :

Ocean Geoid DeterminationThis ca tegory inc ludes a l l i n v e s t i g a t i o n s f o r t h e d et e rm i n at i onof t h e geometry of mean se a l e v e l u s in g a l t i m e t r y d a t a a l o ne o r i ncombinat ion wi th o the r da t a typ es .The s a t e l l i t e al t i m et er observa t ions provide measurements of thes a t e l l i t e h e i g h t above t h e o c ean s u rf a c e . This da ta can be usedd i r e c t l y t o es t im a te the ocean geoid , p rovided th e s a t e l l i t e p o s i t i o n

c a n be de te rm ine d wi th s u f f i c i e n t a c cu rac y a nd /o r e r ro r s i n s a t e l l i t ep o s i t i o n c o r r e c t e d .I n v e s ti g a t i o n s i n t h i s c at eg o ry may c a l l f o r the c om bina tion o fa l t i m e te r in fo rm at ion wi th ge o id in fo rm a t ion ob ta ine d f rom e x i s t i ngs u r f a c e g r av i m et r y, s a t e l l i t e g r a v i t y f i e l d i n f o rm a ti o n and geocen-t r i c s t a t i o n p o s it i on .One of th e important r e s u l t s expected t o be obta ined f rom theGEOS-C a l t i m e t e r i s improved d e f i n i t i o n of th e ocean geoid .ent, worldwide knowledge of the ocean geoid i s ava i lab le on ly f roms a t e l l i t e g r a v i t y f i e l d d a t a which, a t b e s t , d e f i n es v a r i a t i o n s w i thwidths of the order of 1500 kilometers (about 900 m i l e s ) o r l a r g e r .T h e s a t e l l i t e a l t i m e t e r , with prec is ion and/or accuracy of 1 t o 2

meters (40 t o 80 i n ch e s ), h as t h e p o t e n t i a l f o r g r e a t l y i n cr e as i ngknowledge of the ocean geoid i n those su bs ta n t ia l pa r t s o f t he oceanwhere no deta i led s u r fa c e g r a v i t y d at a e x i s t s , as w e l l as c on t r ib -u t i ng t o inc r e a sed a c cu rac y i n those a r e a s where s u r f a c e g r a v i t y ando t h e r t y pe s of g r a v i t y d a t a e x i s t .

A t pre s -

Ocean TidesA t present most measurements of ocean tides a re made a t c o a s t a ls t a t i o n s where t h e t i d a l e f f e c t s a r e s t ron g ly in f lue nc e by loc a l

b a th y m e tr i c e f f e c t s . Although s e v e r a l t h e o r i e s e x i s t t h a t pe rm i tth eo re t i ca l computat ion of deep ocean t i d es , on ly l i m i t e d numbers ofmeasurements of deep ocean t i d e s have been made ut i l i z i n g bottom t i d emeters.

The GEOS-C a l t i m e t e r h as t h e p o t e n t i a l f o r r a pi d g l o b a l d e t e m -ina t io n of ocea n t i de s . GEOS-C should a l low eva lua t ion of va r ioust ec hn iq u es f o r r ec ov e ry of t i d e d a t a from s a t e l l i t e a l t i m e t e r

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- 15 -measurements. T o a i d i n t h i s e v al ua t io n , t h e t i d a l a na lyse s o fGEOS-C a l t i m e t e r d a t a w i l l b e c a r r i e d o u t on d a t a c o l l e c t e d i n areaswhere ground tr u t h i n th e form of bottom t i d e meter data i s a v a i l -a b le .

Sea Sta t e DeterminationIn a dd i t io n t o g iv ing the d i s t a nc e between th e spa c e c ra f t andthe ocean sur face , the GEOS-C a l t imeter da t a , t hrough a na lys i s oft h e c h a r a c t e r i s t i c s of t h e r e t u r n p u l se , i s expec ted t o provide in-format ion on th e sea s t a t e . In pa r t ic u l a r , in formation on meanwave height, wave period, and wave propagation direction may bedeterminable .A lthough t h e o r e t i c a l s t u d i e s and a i r c r a f t r a d a r a l t imeter dataana lyses have been c a r r i e d o u t, c o ns id e ra b le e f f o r t i s needed t o

determine the degree t o which var ious types of sea s t a t e d a t a canbe ext rac ted f rom a s a t e l l i t e a l t i me t e r and t o i d e n t i f y t h e b e s tmethods fo r carr yin g out ex tr ac t i on of th e information. Most oft h e i n v e s t i g a t i o n s p la nn ed f o r GEOS-C f o r sea s t a t e d et er m in a ti o nana lyses a re a imed a t e v a l u a t io n of f e a s i b i l i t y and i d e n t i f i c a t i o nof be s t methods through comparison of r e s u l t s ob taine d from th eGEOS-C a l t i m e t e r w i t h ground t r u t h i n f o r m t i o n on s e a s t a t e andwith da ta obta ined f rom a i rc ra f t -borne radar ins t ruments .I n a d d i t i o n t o a n a l y s i s of GEOS-C d a t a i n term s of s e a s t a t epa ram e ter s , t he ob je c t i ve s th e se in ve s t ig a t i ons inc lude develop -

ment of information f o r u se i n t h e d es ig n o f f u t u r e s a t e l l i t e r a d ara l t im e te r s and de te rm inat ion o f po t e n t i a l b i a s in t roduce d in toa l t i m e t e r sea su r fac e topography de te rmina t ions due t o sea s t a t e .Quasi -S ta t ionary Depar tures f r o m the Marine Geoid

This ca tegory inc ludes a l l a lt im e te r data ana lyses des igned toi n v e s t i g a t e no n pe ri od i c d e v i a t i o n s o f sea l eve l f rom the expec tedvalues based on present knowledge of t h e g r a v i t y f i e l d .c lude s a na lyse s o f a l t i m e te r da ta t o de te rm ine sea s l o p e s a s s o c i a -ted with such phenomena as currents and wind se tup.I t a l s o i n -

The sea sur fa ce topography t h a t w i l l be measured by the GEOS-Ca l t i m e t e r i s a f u n c t i o n p r i m a r i l y o f v a r i a t i o n o f t h e f o r c e ofgr av i t y over Ear th ' s sur fac e , changes i n a tmospher ic press ure fromp o i n t t o p o i n t o n t h e oc ea n s u r f a c e , d e n s i t y s t r u c t u r e of t h e watercolumn, su rfa ce wind ef fe c t s , dynamic ef fe c t s due t o ocean cu rr en ts ,and t i d a l e f f e c t s . I f o nl y g r a v i t a t i o n a l f o rc e s ( i nc lu d in g r o t a t i o n )were p res ent , the sea s ur f ace topography would co inc id e wi th th egeoid.- more -


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- 16 -

The e f fe c t s of a tmospheric pressu re va r i a t io ns , wind forc es ,a nd t ide s a r e t ime-var iab le wi th a reasonably h igh temporal f r e -quency. The e f fe c t s of den s i t y s t r u c t ur e of the water column andc u r r e n t s a r e u s u a l l y c o n si d er e d t o b e q u a s i - s t a t i o n a r y d e p ar t ur e sfrom th e geoid , even though the e f fe c t s of cur ren ts do s h i f t overr e s t r i c t e d a r e a s of t h e s u r f ac e .

One of t h e prima ry aims of N A S A 's Earth and Ocean Physics Ap-plications Program (EOPAP) i s t o dete rm ine, from a l t i m e te r meas-urements , depar tures of s ea s ur fac e topography from th e marinege o id due t o wa te r m otion . The r e ason fo r t h i s in t e r e s t l i e s i nthe fa c t t h a t the v el oc i t y and volume of water i n motion can beinfe r red f rom these depar tures .Gra vi ty Model Improvement

This c a t e gory include s a l l a na lyses o f GEOS-C a l t i m e t e r a n dt racki ng da ta which has the u l t i ma t e ob jec t iv e of de te rmining animproved Ear th gr av it y f i e l d model. These inclu de both normalper turba t ion ana lyses combin ing GEOS-C t r a c k ing da ta w i th da tafrom o th e r s a t e l l i t e s and a na lyses i n which the a l t im e te r ge o idh e i g h t in fo rm a ti o n, s a t e l l i t e - t o - s a t e l l i t e t r ac k i ng exp erim ent r a t ei n fo rm at ion , o r o th e r t r a c k ing da ta a r e c ombined wi th e x i s t in g in -formation f o r gra vi ty f i e l d model improvement.Improvement of th e e x is ti n g g r av i t y models i s r e qu i r e d to

ac hi ev e EOPAP go al s from th re e vi ew po in ts . F i r s t , s a t i s f a c t i o nof a number of EOPAP goals requires improved s a t e l l i t e o r b i t de-termin at ion which, t o a la rg e ex te nt , depends on an improved grav -i t y model. Second, determi nat io n of e f fe c t s of ocean cu rre nt s onsea sur fac e topography requi res h igh accuracy i n geoids wi thwhich a l t im ete r-d er iv ed sea su rfa ce topography can be compared.Inc reased geoid accuracy requ i res inc reased accuracy i n knowledgeo f t h e g r a v i t y f i e l d . F i n a l l y , i n t e r p r e t a t i o n o f an improvedg r a v i t y f i e l d o f f e r s t he p o t e n t i a l o f increased understanding ofp la t e te c to nic s , and th ere fo re , of t he mechanisms producing ea r t h-quakes.Gravi ty f i e l d in format ion can be de r ived f rom GEOS-C d a t a i nt h r e e w a y s : (1) by combining inf orm atio n on the pert ur ba tio ns ofGEOS-C from tracking da ta with data f rom other s a t e l l i t e s i n ag e n e r a l p e r t u r b a t i o n a n a l y s i s ; ( 2 ) by ana lys is o f s a t e l l i t e - t o -s a t e l l i t e t r ac k in g d a t a i n t h e same manner a s Lunar O rb it er andApollo data were a n al yz ed t o o b t a i n r e s i d u a l l i n e - o f - s i g h t a c c e l -e r a t i on s o r compat ible gra v i ty anomaly informat ion; and ( 3 ) by

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- 17 -transforming altimeter geoid height data to gravity anomaly infor-mation. The investigations also include the combination of GEOS-Cdata with gravity field information from other sources.

Geological InvestigationsOne important use of the geoid results to be derived from the

* GEOS-C altimeter data is interpretation in terms of the geological andgeophysical significance of the results. The GEOS-C altimeter resultscan be of particular value in extending information to areas in whichlittle or no surface gravity information presently exists.Solid-Earth Dynamics

This category includes a l l analyses involving the determination ofEarth tides, polar motion, and changes in rotation rate of Earth. Italso includes determination of very precise positions on Earth's surfaceusing GEOS-C tracking data for such purposes as determination of faultmotion and crustal plate motion.

High precision tracking of the GEOS-C satellite, particularlyby the submeter precision laser systems, allows derivation of im-proved information on the dynamics of the solid Earth. Determi-nations can be made of the effects of solid Earth tides and of themotions of Earth's pole including Chandler motion, yearly motion,and the diurnal wobble.Intercomparison, Evaluation, and Calibration of Instrumentation Systems

This category includes all investigations whose objective is theevaluation and calibration of altimeter, satellite-to-satellite tracking,and ground tracking instrumentation to be used with the GEOS-C mission.Evaluations of the on-board instrumentation and the ground systems areincluded.related to instrumentation technology are in this category.All instrument intercomparison investigations and studies

Since the satellite-to-satellite experiment involves new instru-mentation, special emphasis will be given to evaluation and calibrationof these results,

Ground Truth DeterminationThis category includes all investigation whose objective is the

collection of data from ground, ship, and aircraft based systems andthe use of this data to evaluate satellite system characteristics.

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- 18 -Tracking Station Location Improvement

This category includes all investigations to determine the locationof tracking stations where the objective is geodetic in nature and not forEarth dynamic purposes,Several types of tracking data taken using the GEOS-C satellite canbe used to provide improved station location information that will beuseful in support of altimeter calibration and to support other projectobjectives. GEOS-C will provide data from new stations, data of higheraccuracy than previously available, and data from new instrumentationtypes such 3 s very long baseline interferometer (VLBI) measurements.

Orbit Determination ImprovementIndirectly, GEOS-C can be expected to support improved orbit de-termination by providing improved gravity field information. However,this category will emphasize new types of tracking information such asthe satellite-to-satellite tracking experiment and altimeter data andits capability to support improved orbit determination.

Data Manag emen /Information Proce s ingThis category includes investigations whose objective is the devel-opment of methods and techniques for managing and processing the datataken by the various instrumentation on the GEOS-C spacecraft. Thisincludes the development of data editing and preprocessing techniques.Specifically, investigations are directed toward those systems expectedto be most useful in future Earth and ocean physics applications acti-vities and involve advanced techniques applicable to future activities.

Unique S Y Stern InvestigationsThree GEOS-C investigations are uniquely associated with a particularinstrumentation and do not fit into any of the preceding 12 categories,One investigation deals with atmospheric studies utilizing satellite-to-satellite tracking experiment data taken through the atmosphere whilethe other two relate to altimeter and to the C-Band system.

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- 19 -PRINCIPAL INVESTIGATORS

GEOS-C investigations will be conducted by many membegs of thescientific community. Principal investigations are listed by in-vestigational category.Ocean GeoidBlack, Dr. H. D.

Chovitz, B. H.

Dohler, G. C.

Gaposchkin, Dr. E. M.

Hadgigeorge, G.

Jordan, Dr. S. K.Lambeck, Dr. K.

Mather, Dr. R. S.

Johns Hopkins University, AppliedPhysics LaboratoryNational Oceanic and AtmosphericAdministration (NOM)Department of the Environment,Ottawa, CanadaSmithsonian Astrophysical Obser-vatoryAir Force Cambridge ResearchLaboratoryThe Analytic Sciences CorporationObservatorie de Paris, Mendon,FranceUniversity of New South Wales,Australia

Siry, Dr. J. W. NASA Goddard Space Flight CenterTolson, R. R. NASA Langley Research Center

Ocean TidesDohler, G. C.

Hendershott, Dr. M. C.Kuo, Dr. J. T.Mofjeld, Dr. H. 0.Siry, Dr. J. W.

Department of the Environment,Ottawa, Canada

Scripps Institute of OceanographysLamont-Doherty Geological ObservatoryN O MNASA Goddard Space Flight Center

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- 20 -Sea S t a t eBarr ick , D r . D. E .Black, P. G .Gower, D r . J . F. R.

Mil ler , D r . L. S.Pie rson , D r . W. J .

Ross , D.Walsh, D r . E. J .Wells, D r . W. T.

Whitlock, C. H .

NOAAN O MMarine Sc iences Direc tora te ,V i c t o r i a , B. C . , CanadaApplied Science Asso cia tes , Inc .Un ive r s i ty I n s t i t u t e o f Oceano-

graphyNOAANASA Wallops Fl ight CenterWolf Research and DevelopmentCorporat ionNASA Langley Research Center

Qu asi -St ati ona ry Dep artures from th e Marine GeoidApel, D r . J . R. NOAALe i t a o , C. D. NASA Wallops F l i gh t Center

G ra v it y Model ImprovementChovitz, B. H .Khan, D r . M. A.Rapp, Dr . R . H .S i r y , D r . J . W.Sjogren , W. L.Wong, L.

NOAAComputer Sciences CorporationOhio S ta te Univ ers i tyNASA Goddard Space F l i g h t C e n t e rJ e t Propuls ion Labora toryThe Aerospace Corporation

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- 21 -Geologica l Inves- t iga t ionsKaula, Prof . W. M. Unive r s i ty o f C a l i f o r n ta ITalwani, D r . M.

Solid Earth DynamicsBower, D r . D. R.

Douglas, B. C.

Lamont-Doherty Ge ol og ic al Ob servato ry

Department of Energy, Mines andResources, O t t a w a , Canada

NOAASmith, D r . D. E. NASA Goddard Space Flight CenterTapley, D r . B. D. Unive r s i ty of Texas

Bryan, J . W.Dooley, D r . R. P.Lutz, G .

Martin , D r . C . F.

Godbey, T. W.

Ground TruthMourad, A. G.Pie rson , D r . W. J.

Tracking S t a t io n Locat ionF i s h e r , D.

NASA Goddard Space Flight Center,Technology Service CorporationDFVLR Mobile Rakentenbasis,6 .

Federal Republic of GermanyWolf Research and DevelopmentCorporat ionGeneral Electric Company

Bat te l l e Memor ia l Ins t i tu teU n i v e r s i t y I n s t i t u t e of Oceanography

Tel-Aviv University, Tel-Aviv,Is ae1- more . -


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- 22 -Tracking S t a t i o n .L.oca.tipn .- .continuedK r a b i l l , W. B. NASA Wallops Fl ight CenterMarsh, J. G . NASA Goddard Space Flight CenterEscobol, P.Wilson, D r . P.

Orb i t Dete rmina t ionBalmino, D r . G .

Black, H. D.

J e t Propuls ion LaboratoryTechnischen U ni ve rs i t at , Munchen,Federal Republic of Germany

Cen t re Nat iona l D 'Etudes Sp a t ia le s ,FranceJohns Hopkins Uni ve rs ity , Applie dPhysics Laboratory

Data Management/Information ProcessingGodbey, T. W. General Elec t r i c Company

Unique System In ve st ig at io nsHofmeis ter , D r . E. L. General Electric CompanyJackson, E. B. NASA Wallops Fl ight CenterLiu , A. S. J e t Propuls ion Laboratory

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- 23 -J'DELTA 'LAUNCH VEHICLE

GEOS-C w i l l be launched from SLC-2W a t the Western Test Range, CA,by a two-stage Delta l aunch vehic le .meters (106 f e e t ) long, with a maximum body diameter of.-2.4 m (8 f e e t ) .The Delta has been launched su cc es sf ul ly 90 percene of the t i m e f o rthe pas t 14 years .F i r s t Stage

The f i r s t s t a g e is a McDonnell Douglas modified Thor booster incor-The

The vehic le Ss approximately 32

m

pora t ing four s t rap-on Thiokol Cas tor I1 sol id-fue .1 rocket motors .boos te r i s powered by a Rocketdyne M B - I 1 1 B engine using l iquid oxygenand l i q u i d hydrocarbon pr op el la nt s. The main engine i s gimbal-mountedt o p rov ide p i t c h and yaw c o n t r o l from l i f t q f f t o main e q i n e c u to ff(MECO). Two l i q u i d - p r o p e l l a n t v e r n i e r en gi ne s p ro v id e r o l l c o n t r o lt hr ou gh ou t f i r s t s t a g e o p e r a t i o n and p i t c h and yaw cont ro l f rom MECOt o s e p a r a t i o n o f t h e f i r s t and s eco nd s t a g e s .Second Stage

The second stage i s powered by a TRW l i q u i d - f u e l p r es s u re - fe d ~TR-201 engine t h a t a l s o i s gimbal-mounted t o provide p i t c h and yawco nt ro l th rough second s tag e burn.e i gh t f ixed nozz les , p rovides r o l l cont ro l dur ing powered and coastf l i g h t as w e l l as p i t c h a nd yaw c o n t r o l du r ing c oa s t a nd a f t e rsec ond s t a ge c u to f f . Two f ixe d noz z le s, f e d by th e p rope l l a n t -t a nk he l ium p re s su r i z a t ion s y s e m , p r o v i d e r e t r o t h r u s t a f t e r 'sp ace-c r a f t s e p a r a t i o n .

A n i t r o g e n g a s sys tem us ing

1 . . . . .. .* ' .

. ,

- molrer-

1 I 1 I I I


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- 24 -DELTA FACTS AND FIGURES

The Delta l a unc h ve h ic l e p ro je c t i s unde r the the t e c hn ic a lmanagement of t h e Goddard Space F l i g h t C en te r, Gr ee nb el t, Maryland;McDonnell Douglas As tr on au tic s Co., Hunt ingto n Beach, C al if o rn ia ,i s t he p r im e c on t r a c to r .g e n e r a l c h a r a c t e r i s t i c s : The two-stage Delta has the fo l lowing

Height 3 2 meters (106 f e e t ) i nc lud ing sh roud ;Maximum diameter 2.4 m (8 f t . ) w i t ho u t a t t a ch e d s o l i d s ;L i f t o f f w e i g h t 110, 165 kg (243,190 l b s . )L i f t o f f t h r u s t 1,375,000 newtons (307,000 b s . ) , i n c l u d i n gfour s t r a p - o n s o l i d s .F i r s t S ta ge ( l iq u i d only) c on s i s t s o f an extended long tank Thor,produced by McDonnell Douglas As tr on au ti cs Co., wi th M B - 1 1 1 B engines ,

produced by the Rocketdyne Divi sio n of Rockwell In te rn at io n al , and hast h e f o l l o w i n g c h a r a c t e r i s t i c s :A diameter of 2.4 m (8 f e e t ) ;A h e i g h t o f 18 (60 f e e t ) ;P rope l l a n t s o f RP-1 kerosene as the fu e l and l i qu id oxygen(LOX) as the o x i d i z e r ;A t h r u s t o f 780,000 N (175,000 b s . ) ;A burning t i m e of about th re e minutes and 48 seconds;A weight of a bou t 84,600 kg (186,000 bs . ) e xc lud ing s tr a p -ons o l i d s .S tr ap - on s o l i d s c o n s i s t o f f o u r C a s to r I1 s o l i d p r o pe l la n troc ket s produced by th e Thiokol Chemical Corporat ion, with th efo l lowing fea tures :A diamete r of 0.8 m (31 i n . ) ;A h e i g h t o f 7 m (23.6 f e e t ) ;A t o t a l we ig ht o f 17, 900 kg (39,400 b s . ) f o r fo u r 4,475 kgA maximum t h r u s t o f 925,600 N (208,000 b s . ) f o r fo u r 231,400 NA burning t i m e of 38 seconds

(9,850 bs . ) each(52,000 b s .)each

Second St ap e: Produced by McDonnell Douglas A st ro na ut ic s Co.,u s ing a TRW-201 rock et engin e; major co nt ra c t or s f o r th e ve hi c l e i n-e r t i a l guidance system located on the second s tage a r e HamiltonStandard and Teledyne.P rope l l a n t s : Liquid--Aerozene 50 fo r th e f u e l and Ni trogenTet roxide (N204) f o r t h e o x i d i z e r .

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- 2 5 -Diameter: 1 . 5 m (5 f e e t ) plus 2.4 m (8 feet) attached ring.Height: 6 . 4 m ( 2 1 fee t )Weight: 61,800 kg (136,000 lbs.)Thrust: About 42,300 N (9,500 lbs.)Total Burning Time: 3 3 5 seconds.

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- 26 -LAUNCH OPERATIONS

NASA launch operations from i t s W es t C o as t f ac i l i t y a re con-du ct ed by th e Kennedy Space Ce n te r ' s Unmanned Launch Ope ra ti on s,Western Launch Op era tion s D iv is io n (WLOD). This f a c i l i t y i s l o c a t -ed a t Vandenberg A i r Force Base, ne ar Lompoc, C a li fo rn ia , appr oxi -mately 125 m i l e s northwest of Los Angeles and 280 miles south ofSan F ranc i sco . Launch f a c i l i t i e s a r e l o ca t ed on a promontory whichju t s i n to t h e Pa c i f i c Ocean n ea r Po in t Arg u el l o. This makes i t pos-s i b l e t o l aunch t o the sou th and p lace payloads i n po la r and near -p o l a r o r b i t s w i th o u t o v e rf l y ing p o p ula ted a rea s .

GEOS-C w i l l be launched by Delta 110 from Space Launch Complex2 West, which has been exten s iv ely updated over the y ears t o acceptth e var iou s Del ta conf igur at i ons , includi ng the powerfu l new ve rs io nnow i n us e. The GEOS-C miss ion w i l l be the second launch th is y e a rfrom t h i s complex. De lta 107 was successfully launched on January 2 2t o p l ac e LANDSAT-2 i n a n ea r p o l a r , s un -sy nchron ou s o rb i t a t an a l t i -tude of 920 k i lometers (570 s t a t u t e m i le s) .

Prepara t ions fo r the l aunch of GEOS-C began i n l a t e J a nu ar y w i t hth e a r r i v a l of t h e De l t a 110 f i r s t and s econ d s t ag es a t WLOD f o r p r e -l imina ry checkout and er ec t io n . The GEOS-C s p a c e c r a f t w a s shippedfrom the Johns Hopkins App lied Phys ics La bor ato ry i n mid-February anda r r i v e d a t KSC/WLOD d ur in g t h e t h i r d week of February .

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.

GEOS-C LAUNCH EVENTSTIME VELOCITY

EVENT (SEC. ) KM ALTITUDE METERS/SEC (FT. /SEC. )MILESLif tof f 0 0Four Soli d Motor Burnout 9 4.4Four So lid Motor J et ti so n 120 26Main Engine Cutoff 272 96First/Second Stage Separation 280 104Second Stage Ignition 285 109Fairing Jettison 305 126Second Stage F i r s t Cut-off 576 185Second Stage Res tar t 3419 842Second Stage Second Cut-off 3426 842Spacecraft Separation 3501 840

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02.7

16606 46878

115522522521

0448475

417941744164426778547 4073147315

014941584

1393113914138791422426180237992438124382


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- 28 -GEOS-C MANAGEMENT

NASA Headqua.r.tte.r,sCharles W. Mathews

Franc is L. WilliamsDick S. D i l l e rJames P. MurphyNoel W . Hinners

Joseph B. Mahon

I . T. G i l l a m I V

P. T. Eaton

Wallops Fl ight CenterRobert L. KriegerLaurence C . RossiH . Ray StanleyFrank M . Boykin

Assoc ia te Adminis t ra tor forAppl ica t ionsDi re cto r of S pe cia l ProgramsGEOS-C Program ManagerGEOS-C Program Scient is tAssoc iat e Adm in i s t ra to r f o rSpace ScienceDi r e c to r of Launch Vehicleand Propulsion ProgramSmall Launch Vehicle andInternational Programs ManagerDelta Program Manager

Di r e c to rPro j ect ManagerP r oj e ct S c i e n t i s tSpacecra f t Sys e m s Manager

Gpddard. Sp.ace, F.1.igh.t. Ce.n.t,er

D r . John F. Clark Di r e c to rRobert N. Lindley Di r e c to r of P ro je c t sJohn B. Zega l ia Mission Operations SystemsManagerand Mi ssi on Sup por t ManagerRichard H. S cl af fo rd Network Suppo rt Manager

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- 29 -

Goddard Space Fl-ight Center- con '.t .)Robert C. Baumann Associate Director of Projects

for Delta

Francis J. Lawrence Delta Mission Integration EngineerKennedy S~ 3c. e.en.ter

Lee R. Scherer RCrectolJohn J. Neilon Dj-rector, Unmanned Launch OperationsHenry R. Van Goey

Wi mer "Bud t Thac e

Manager, KSC Western Launch Oper-at ions Divis ionChief, Delta Operations, LaunchVehicle Engineering Branch

Carl Latham GEOS-C Spacecraft Coordinator

Experiment ManagersC. L. Purdy

E. B. JacksonB. J. Trudell

C. C. Stephanides

D. AnderleI. M. Salzberg

Radar Altimeter ExperimentSystems Manager, NASA WallopsFlight Center

C-Band Experiment System Manager, WFCSatellite-to-Satellite ExperimentSys em Manager, GSFCLaser Experiment SystemManager, GSFCDoppler System Manager, NWLS-Band Experiment System Manager, GSFC

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Supp r Organ .z.a.t.ionsSpacecraft and Experiment Hardware Contractor: Applied PhysicalLaboratory, Johns Hopkins UniversityLaunch Vehicle Contractor: McDonald-Douglas Aircraft CorporationLaunch Site: Air Force Western Test Range, Vandenberg Air ForceBase, CAATS-6 Project: Dr. James E. Kupperian, Jr., Project Manager, GSFCGround Truth: National Oceanic and Atmospheric Administration--Lt. L. Goodman

Naval Research Laboratory--Ben Yaplee

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- 31 -CONTRACTORS

HAFUIWA.REGEOS-C S pa c e c ra f tDelta Launch VehicleA 1 ime te rS-Band TransponderC-Band TransponderLaser CubesDoppler

SUPPORTComputer Sciences Corp.Wolf Research and Development Corp.Applied Sciences AssociatesRCA Corp.

Applied Physics LabMcDonne11 Douglas Aircraft Corp.Ge ne ra l E le c t r i cMotorolaVega P re ci s io n Labszygo Corp.Applied Physics Lab

Documents

GEOS-C (GEOS 3) Press Kit