i

EhrVIRONMENTAL RESEARCH S14TELLITE-18 1 t

DATA RXDUCTION AFD ANALYSIS

V~lutxt.~! 1 SATETrlrlrTE DESCRIPTIO'I AND OPERATIONS

(Terminal FIi.,.?' t Report) Jdy k.33

LAtFREMCli: E. P ETE.PSON DUML'S .GAY' JBER

~ ~ P H E W J. mvrs ht1CHAEl.v R STONE

University of C ~ o r r l i e at San Diego

La ddla, Cd'fornk

JAFtIEE I. - m m Godikd Space ri&i::t Center

Greenbelt, Mcugl.'a:d

, .

c/ Remuch Spolwolled by

AD\XNCEI) IXESEARCH ERQJIiCTS AGENCY Nuclear &t Detccksi 4rfFce

Contract No. M>-47nt-68-C0108 Air Fern Space md hlisr;b Syster.1~ Organi~~cion

h A n g k Califorma

-c &%a .bii $ : ~ ~ - ~ 3 ~ .-.A=-. *.. .&;,d+x. .% .. s-,

https://ntrs.nasa.gov/search.jsp?R=19690013171 2020-02-26T22:02:50+00:00Z

Table of Contents PeBe

L i s t o.t mles and Figures .................................... ................................................ References .. ,-. ill.

I)etec.tor Cqlmu?nt ......................................... ............................. Geiger-MueUer C u t e r (G-M)

.................... Li-drLL"ted Farticie Detector ( S S I ) ) ,,.

.................. &*face Bmrier Particle atector (SXJ) .

...................... . Low Bnergy PE-TticIe Detector (m) .............. Shielded Gams-Ib>- Caunter (shielded Gazra) --- C a t e r (Zhra3, -1 ....... .................-

Detector Supsaary ....................................

Data Reduction Sjatem .............~.....~...,.~C.,..,......

vii

I Satellits Operation ........................................ 36

S~~0fRedu~ti0n~dAna~~f8......~.............+...... 39

Tables snd Mgures

Tables - T i t l e Page

1 WS-18 Expriment Nominal Characteristics.. .......... 10

....................... 2 motqpph 0f ERS-1% ... ...... 5

3 B1xkCiagI.Qrn ....................................... 6

......................... b Received Anslog 3ata Record 9

5 Calibration of hcference and Temperature Channel . . , . ll ........................... 6 Calibratim of Channel U. 12

Reference S&r Sensor .............................. Mesic%en S O W Sensor (l'xpical) .....................

.................... G-M and %face Barrier ktectcr

Saffd State Detector ............................... ........................ Low-Ibergy Detector

Shielded Gamna Ray Detector ......................... Garma Re.y 3etector ..................................

.................. Ecliptic P W e Projectiw of Orbit

............ Solar MeriCian Plane Projection of Crbit

Data Playback System ............................... .......................... Com_Duter Reduction SysCem

Data Coverage ...................................

References

(1 ) ''system Description Document Octahedral Research Satel l i tes ,

Nark and 3 (ERS 1 t and 18) " TRW S p tems , Redondo Beach,

i Calif. , Boc-mnt Mo. 03565-6001-~00~, August 1967. I'

( 2 ) "lbvironment~ Reseaxh Satellite-17, Data Reduction and ~ n a l y e i s "

1, Satel l i te and Reduction Systens, U~ivers i ty of California, - . .

. - . . San Diego, La Jolla, California, Report U C S D - S ~ - ~ ? - ~ , 1967. ? . ..

< + . - ~ i

--. 1 ( 3 ) "&virop-mental Research Satel l i te tie. 18 ( a s - Msrk 111 -

I ~adia+,ion) " Goddard Space Flight Center, Greent-lt , Maryland,

Preface

This report ser ies describes resul ts obtair'cd from the Environmental

Research Satell i te-I8 (ERS-1.8), one of a ser ies cf small s a t e l l i t e s ac-

veloped cver the wst several years by TRW Systens through several A i r

Force programs. The Octahedral Research Sa t e l l i t e Mark I11 (ORS-111)

was one of these series, designed t o pro-Jide a complete monitoring of

radiations In space and t o study the radsation background problems associ-

ated w i t h the nuc1ea.r t e s t de tec t iw devices on the Vela Sa t e l l i t e

Program. Two 0%-111 sa t e l l i t e s were developed and constructed in order .- -

t o measure ionizing radiations throughmt the magnetosphere t c the

al t i tudes of the present Vela s a t e l l i t e , approximately 18 %. The first

one (D,s-17) which was launched on 20 Juljr 1965, prodwed data for np-

pscximEItely 3-1/2 months. The ERS-18, w i t h a modified payload, vms

launched April 28, 1967 in a orbi t with a highes perigee, and hr.s pro-

duced nearly continuous coverage for more than one year.

In accordance with procedures established under the ERS-17 data

redcc+,ion contract, the resul ts of the EXG-1s w i l l be published a s a

series or' reports: in d d i t i o n to papers i n sc ient i f ic journals, where

appropriate. The ERS-1': ser ies consisted of seven v~lumes, containing

a description of the EHS-17 and the data r ed~c t ion system, f ive volumes

ccmtaining a l l the data i n form of machine plotted graphs, and a f i n a l

repvrt. The repcrts on the ERS-18 wiil be issued at approximately

quarterly intervals, and w i l l have a niodified format because of the

econmic impracticality of piblishing the ent i re mass of data. Thls,

the F i r s t Quarterly o r Tenninal Fl ight Report, contains a description

of the s a t e l l i t e , the data redwt ion procedures and a res lae of the

s a t e l l i t e ' s operation. The second Quarterly Report w i l l contain selected

sample data and its interpretat ion, the th i rd may contain selected solar- I /

7 f jerrestsial events, e t c . 2 p .P The .;RS-I11 s a t e l l i t e s were constructed by a grollp within the r . ,

Solid Sta te Physics Tyaboratory of TRW Systems wider the direct ion of '

/' Dr. Joseph De~ney. The work of many individuals, indicated i n the

previous report ser.ies, contributed t o the success of these s a t e l l i t e s .

4' Particulwr mention i s due M r . Randy M!r+,in, who was generally responsible

/ ,. f o r the construction, integrat ion and t e s t of the s a t e l l i t e system.

/ Dr . James Vette, formerly of the Aerospace Corporation, pro-rided

/' the i n i t i a l a p t u s leading t o the development of the ORS-111, an& has

continually pn3vided technical and sc ien t i f i c oversight of these projects,

~II addition t o d i rec t contributions in detector design, data analysis,

and interpretet lon of the sc ien t i f i c resul t s .

The University of Califoxmi& group under the direct ion of

D r . Laurence Peterson has been p r i n c i a l l y responsible f o r the reduction

&nd analysis of dab received from these s a t e l l i t e s . The computer

programs were or ig inal ly wri t ten by Mr. Louis Huszar f o r tne ERS-17,

a d were modified by him for the EXS-18. Tile data ghyback system was

designed, assembled and monitored i n a most expedient mander by

Y ! . Paul Brissenden . mny undergradcates have -contributed t o the data

playback snd computer reduction operations,

This research a t UCSD was suppiirted through the Nucless Test

Detection Office, Advanced Research Projects Agency, Colonel

R. C. Browis of t h a t off ice has been most h e l p f i l and underst.~mdj,n.g,,

UCSU i s under contzact through A i r Force Space and Missile Syzteme

Organization, Los Angeles , California . Major J u l i a n Salas has a l s o

contributed much t o the i n i t i a t i o n and d i rec t ion of t"his project .

Laurence E. Peterson

Abstract -

The 17.2 Ib . Xnvironmental Hesearch s a t e l l i t e - 1 8 (ORS-111-B)

c a r r i e d a s e t of f i v e radiat ion detectors designed t o measure charged

p a r t i c i e s , X-rays, gamma rays, and cosmc rays i n the near B r t h en-

v i r~nmen t , The s a t e l l i t e was launched on Apr i l 28, 1967 i n t o s, highly

e l l i p t i c a l o r b i t wnose i n i t i a l apogee a l t i t u d e wss 111,200 kilometers

and. i n i t i a l perigee a l t i t u d e wzs 3,600 k i lc ine te~c . Detectors sens i t ive

.to trapped p a r t i c l e s include a so l id s t a t e detect.or f o r e lectron fluxes

above 0.4 Mev and grotans 8-21 MEV, a LOW energy s c i n t i l l a t i o n c o u n t o ~

f o r e lec t rons grea te r than 1 G O kev and protons greater than 1-8 14ev.

A s e t of Geiger4fuellercounters detected so lar X-rays i n the 1-14 1

range, and electrons above 40 kev. G a m ray countiilg r a t e s between

30 kev a r~d 10 Xev, a s wel l a s the t o t a l cosmic ray f lux , were provided

ba- the "dual-gamma" counter, a la rge N ~ I ( T ~ ) crystal. surrounded by a

charged p a r t i c l e sh ie ld consis t ing of p l a s t i c s c i n t i l l a t o r connected in

e l e c t r i c a l anticoincidence with t h e c t i l t r a l s c i n t i l l a t o r . Signals from

most channels were converted t o analog voltages by logari t imic count

r a t e meters. Each channel was sampled about once a minute t o modulate

a sub:ars-ier o s c i l l a t o r j.n t h e t e l e m e t r y system. Several low counting

r a t e channels were converted t o a q-daai-digital f o r m t before sariipling.

Data hss been received nearly continuously from launch u n t i l

termination on: June 3, 1968, and has been monitored occasionally t o

assess the performance of the I n s t m e n t a t l o n . Mapletic tapes a r e

v i i

present ly being glayed back, decommutatec.! and reduced i n a semi-axtomtic

systein a t the l lnivessi ty cf California , San Diego, where t h e data a r e

a l s o checked, edi ted m d assenbled in sequent ial order f o r ana lys is and

pA3tting. Torrected counting r a t e s frcm tile pr inc ipa l channels have

been hand-plotted as a f'unction ~f t i n e f o r s a t e l l i s 2 o r b i t s 26, 27 and

28, which covers the period from June 18 t o June 23, 1967.. The remainder

of the data has been p e r i ~ 3 i c a l l y sampled t o indicate the s a t e l l i t e

s ta tus . Data i -e tr ieval 1:il.l cover abudt, a@ of the time during the f i r s t

one year c, operation. Many of the EI~S-18 data w i l l be machine-glo$ted

against sine, and se3.ected portions w i l l be presented i n futirre reports

in t h i s se r ies . Tile date. w i l l a l s o be eventuaily a n i 2 a b l e i n a mag-

ne t i c tape f o O m 2 f o r f 'urther analysis .

v i i i

" /' In t r & u c ~ - ~

i i'

3rteminat-ion of the radiation conditims in the near Barth cn-

i" i ld ~5 maeiit ,..equires synoptic obse,natien- over a large region of space

i i with aetectors c2 cm.sickrab3.e dynidc rmge and sensitive to many dif-

ferent ionizing species. The .&tahodral Bnsearch Satellite Mark III /

i s 'desigried for this purpose mff has ari instrument cuqlement of radia-

tion detectors to measure charged -particles, c o w c rays, li-raqs, and

i g~rnsa ra.vs. , T m satellites i z ~ this series hve bees. success f iv

, f 'hunckd. The f k s t , desmated the Ehdw-nt&L Research Satellite-17

d (~Rs-~7) was ls,unched-July 20, 1%5 h t o a highly m i p t i c a l orbit of

- apogee 112,230 M-ters a24 perigee 1% kileters altitude and ;ns- ;d

/ a c e d data for over thee months at a 30$ coverage rate. The secad

I=-I=-B) -as laJnched as the E~RS-18 into an orbit of 111,20(3 Wfome-

t e r s apogee and 6,m Mmeters peraee altitude on mril 28, 196'7,

a?& has prodaced deta a'; aSmt ac coverage 1e.d for over a year. .

. r ' Potb satziiitto trp-rse the o1c.ter tspped radiation zme, the outer

rwgaetosphere, wc! resid~iin the interplanetary regim for a consider- i 3

qble period of time; a.5.-17 also swept thnmgh the .'Lnner zme. T h i s

report catains 3escriptions of the ZRS-18 and the techniques used to

r sbce and a n w e the b t a a t She Usliversity of California, San Diego.

Also k c i ~ d e d is ar; 0-peratimal summry; &ata presentation and

scientific resu1;;s are the sazbject of m t h e r rey-ts.

The I~RS-18 was desigred and developed by a group within the Solid

State P&-sics Labcratory of TRW Systems, Redondo Beach, California.

The basic cocfigurattm of the ORS-211 satellite is a regular octahedroc

neewing 11 inches on e side. Sc?lar cells m m t e d on each of the

faces rovi,*e mt'ficient electrical _parer to operate the experiments and

t5e telemetry sk-stem when the satellite Is illuminated the sun. lio

inte-rnal batterJ- m cummd systen were pm7cided. The sa t e l l i t e ar?d

its detectar cohnpleaent are briefly described 21 the CIS-IST System

Descrirtia 3ocment(l', and the CPS 111-A in Yolme I of' tke EPS-17

(2) report sc:?es . T3e sll'?s,vstm of the satellite ca~sls ted of electrical por,x!r,

=*Anna, telemetry, experiments anc'. sechanical sc;rsctul.e. 'Be elec-

trical. ghier s b s t e m included *he soler-cadi a r r a ~ ar?d s voltage re@-

lat@r. A hal,f -us=-length dipole and mtching network c q r i s e d tie

a t e m a system, "he telemetry s,vsten ineliided an electronic e m t a t o r ,

a subc~xrier osciliator, and the t m i n i t t e r . The detectcr systems

were desigaeci to aeaslLre geampet ica4- tra-aped maat tan, cosmic ~EQ-s,

soLar and galactic *ma rays gcd sohr X-rays. As wifh tie

WS-17, $2 instmmentx constituted the experu-t com1~1en;erit: a

Geiger tube array, a solfd state detector, a =face barrier detector,

Zwo particle s c i n t ~ t i ~ counters, and er iarge gamma rsy scintillation / ,/

counter with aetive anticoLxidence oar t ide shieldbg .

?:;,'' - . . * 4: r' c Phatogmphs of ttte 3RS-111-B, wtth some of the solar panels re-

&/ 4 -

- - / moved, are shown in Figures 1 and 2 and an electr ical block diagram i?

Figure 3. The basic welded alumiaun s b c t u r e weighed 1.9 lbs . , the '

/' j cOnpl&ed sac&llite as -ached weighed 17.2 lbs. A t h s t member

,. c o u p l e d ~ l a u n c ~ accelerations t o the central deck upon which were -- -.

aounted t h e tpmsnitter, high voltage supply, and m y cf the welded

'4 d electrmiemdules . Otaerel~tronicasrcmblies~~remountedon sub- /

i 1 tL decks. r)e$ectors reqcLrFag l i t t l e or no shielding were arranged - t o

. , view outward a t t52 mims corners 0,4 tke octahedron. L

<,b' / , : Rmer was p r a i d d by eight _nanels of N-on-P li) oh-cm solar cells

J

, ,. 102 0ne-b3-~-Dwo cectimeter ce l l s orr each panel, supplying about , d k - 4 uatts of unregulated elestrLcal -r for the averaged projected ==a , . ' >

/ i

of the octahedron. A series voltage regulator pro-rided electrical

/ power at 9.0 * 0.1 FOI~ to tke *&lmetrg end experimeni systems. About

/ I . , -. I . 0:6 watts *as available to +he experime2ts. The transmitter i t se l f

1 /

/' a d the high si33-txge sup@y were suprjPied ~ 5 t h unregulated parre?. An

. end-of-life timer was designed t o remove transmitter paver af ter a ;. 1

/

, n d a d p-aet interval 09 i6 months ( t h a t is, a t the end of August, ' t /

i*)

The antenna wes a conventional half-wave length eipole' fabricated

from half-jzch w2de ribbo3 steel , stiffened by concave forping. It

self-erected fnwl a coiled yosition and projected unsupported fran -L\e

satel l i te . A satching netmric, ccmsisting of a transfomcr with emed

T-t4.'COV17tt Ibcu -9

ERS- I8 BLOCK OlAGRkM /'

.Figure 2 - A block diagram of the satellite. Counting rate radiation detectors were converted to analog voltages with count rate meter, or by using a quasi-digital technique. Z sampled about 5 seconds each minute and telenetered on a PAI

/

n-1

F i ~ ; m e 2 - A block diagran: of the s a t e l l i t e . Counting rates from the radiation detectors were coklverted t o analog voltages with a logarithmic

i i count rate meter, or by using a quasi-digital technique. Each channel was , I

sampled about 5 seconds each minute and telemetered on a PAM/l?@?.i system. 11 . ,

6 /

, primary and secmdary windings, provided maximum power transfer from 1

/ the transmitter t o antenna.

Temperature ccntrol of the s a t e l l i t e was achieved by ptissive tech-

niques. Good therml coupling of a l l p r t s of ,the vehicle is possible

because of its small size, The design operating temperature i n sun-

l ight was about ljOc, with excursions t o nnminally OOC during the short

perigee eclipses (1/2 hour mru;.) and t o -3o0c during apogee e ~ l l p s e

(4 hours max. ) , which can occur only eight days per year. Temperatures

measured during the s a t e l l i t e l i fet ime were within the design limits,

, usually being about ~ O O C s? the locatioli of the thermisters.

Experiment and h0Usa'Keepbg htb. was telemetered on a PAM/FM/PM /

.saxtern with a nominal .rate& power of YO00 milliwatts a t i35.530 mHz . The peak modulation index is 1.0 -* 7.55 subcarrier osci l la tor was

designed for an -put range of 1.0 volt. Nominaxv 4.8 volts input t o

the commutator corresponded t o a frequency a?-1200 cps and 5.8 volts t o

14C3 cps . Subcarrier frequency was stable t o within f 0.1$ o-Ser the

-25'~ t c ?40°C temperature range. Data from the 16-chsnnel commutator

was f i l t e red by a single RC network of time a n s t a n t .&7 sec. This

results in an infom~lstion bandwidth of abtwt 6 cps. Each c o m t a t e d

channel, as shown i n Figure 3, was sampled fo r a nominal 5 seconds; two

of the channels, numbers 8 and 9, were subcommutated in to 8 additional

channels. In orbi t , the sampling time was 4.7 seconds so that about

74 seconds were required t o read t.he ent i re msin frame, and 5% seconds

for a l l the subcommutator chancels. Most of the data channels on the

/

/;,

,'

ERS-17 and 18 'consisted' @f. analog oueu t s flrm 1ogar i t .W~ count ra te

,,,,// meters, or quasi-digital data from binary scalar-addeys. A typicsi

telemetered analog chart r e c o ~ d received from the WS-18 i s shown i n

j The channel assignments are indicated in Figure 3 and Table 1. I .

; Channels, other than the sync, were limited t o a subcarrier frequency a: f

i range c,9 1280 cps to 14%) cps, corresponding t o a cominal input. r a g e of

/

5?2 t o 5.8 volts. Channel 1 (sync) was identif ied by a range of 1200 cps i . 1

, /:to l260 cps, or an input range t o the commutator of 4.8 t o 5.1 volts.

/ Additionally, the infomation channel superimposed on the sync usually

, was near the 1200 cps level. Subc~Imuutator sync (channel 8-1) was 12

identified by s w i n g a low reference voitcige, nominally 1233 cps, fol- 1 .

lowed by 3 high reference voltage nominslly 1379 cps on channel 8-2. J

'I?reQight temperature calibrations of the subcarrier osci l la tor reference I

I I

' frequencies a re sham i n Figure 5 and a typical channel in Figure 6 . i i

, Housekeeping infcrmation consisted, i n aadition t o voltage,readouts, t . of four temperature readouts on the subccmmtated ch-els 8 and 9.

i

Thermocouples were placed on the upper and lower solar panels, on the

:'large scint,U,?tion counter, and in the central structure. A typical i

i , temperacure channel calibration i s shown in Figure 5 ; the remainder may i

i h' . be found included i n the system description document (1). 6!

I / " I

, An array of sun sensors were instal led with the intent of providing ' i a positive icdication of spin &.xis aspect with respect t o the solar

,/

direction. The meridian sun sensor, shown i n Figure 7 and Figure 1, , a I .'

I .

i

a DIGITAL ,

. . -., . . . .

. . . ,

PLAYBACK . . , , - . . "UTE

r - . - 7

DATE ' DATA START TIME OF

TI ME I st SYNC

T * - . - - - -

............. ........... , , I . .. -;I... ... ..

,- ----. L-- -.-L -.--. - - --+--+ -.. - . .-- - .-. - * ,. , . - . . , . . . & ' I . . . - - , , % . . - * .

.,.IL. I . . I . . t . .- ... ......... ........ 1

- = . ., . ,. . - . . - . . ,

I 1 - . - ; -:-; - - . 7 4 . - . ,. 0003:OO.C

, .~ 0004:OO L - - - ~ .--.-- :-- . - . . . , , 1 - 1 > + : , , ? ' . ---A - . . . . . . . . . . . . . . . . . . . . - . . . , . - - - . -- 1 PHYSICAL RECOHD --A 1

MARKER 25.6 rec.

DUAL GAMMA-RAY (0.6 - 1.0 MeV] , QUASI-DIGITAL ;,-SYNC= -- .....- ........._....... a ___.. __ - ,

t ..................... , ,

SYNC .,- - --.., - -- *?L.-? i- I ..& L.-. ..* .. ... 8_+_t-. . ' L - L A .... &-.- ....... ' . . . . . ' ....I..

, 7 - , , . , . . . . . . . . . . . , ' , . . . , . . , --T.r-...- !.. , , - . . . . . . . . . . . . . . . . . I . f . .:, , '

. . . . . . . . ' ..........

J

- - . - L ' a . , . . . . . . . ., . - L ; ..l

8 i f - . - : . - a . 3 - ' , - , - , . . - , , - . . L ~ i . - - . " " ' . . . . . ..I..........*........ . - . . . . , I . . - . . . * . . -

, , - -> :. ,, , I

! t . , . , 0006:OO.O , , '

i ' , , , - , ; * , . . . . , . , . ' , I ' ' , / I . , , . ' : , ' ! , ; , ; , ! i ! , , I . . ' . . < ,::. , , ; ;

1 ' . . . . . - - . A . . , , . - . .

: t - . I FRAME (16 CHANNEL)- 74 secs. -4

ERS - 18 ANALOG CHART -. MAY 6,19 Figwe 4 - A typic Each chamel Wis . data obtained thrc shown art: playbac! reduction operatic

SOLAR X-RAYS -, \ SURCOM

I I . . < 1, : > , , , , I , . , , : , , . . . . . . , . , . . . . L . i

I ' , ..,.. L . . . . I . 8 .. + - . + i , . I , , , . ....:... . . . . i ...-- . ,' I::+:*J.:.: : - - I - & & L

1.. I * *., , - , . . :L -L.$:J

TIM; OF I st SYNC

INBOUND '0 = 71,730 KM LAT = 1 5 . 2 O LONG =-35.4@

'Ah DUAL GAMMA ( 1 - 2 MeV), QUASI -DIGITAL

- 18 ANAbO6;CHART - MAY 6,1967 Figure 4 - A t jrpical record of the ERS-17 da ta obtaineci soon a f t e r launch. Each ch-me1 was sampled f o r a b o ~ t 5 seconds, and consisted of counting r a t e data obtained tk.rough logarithmic count r a t e meters, o r binary sca le rs . Also shown a r e playtack system ca l ibra t ion records used i n four times r e a l time reduction o p e r ~ t i o n .

TABL

E I

m-1

8

EXPE

RIX

EiJT

NO

KIN

AL

CH

AfW

CT

mIS

TIC

S -

Dis

crim

- D

y7m

lic

lna

t or

Rea

dout

Ran

ge

Sca

' fn

g

Ct~annel

Det

e-to

r A

bso

rber

M

easu

rem

ent

Lev

el

-

Geo

met

ry F

acto

r co

un

ts/s

ec

Fa

cto

rs

Num

ber

oh^

6213

1.2

m

g/cm

~

.ec

tro

ns

>4

0 kev

..

A50

.056

cm

2

3ca

-l.e

r-

!c &

64

Add

er

9-7

Mic

a I EZ

te

rs

P

roto

ns>

75

S K

ev

X-Rays

1-14

8,

1

Go

9 3

LC

R.1

66-6

0, OW

n+ a 6

.6 s

ter

LCRM

120-1

20,0

00

u

- 1

So

if d

68.5

mg/cm2

~le

ctm

re>

40

0 kev

70

kev

G

o - -

LCRM

1 -1

000

11

Sta

te

I -

Alu

min

um

tl =

2n

LCRM

-~~

J-~

Co

,Oo

o

10

Pro

ton

s 8

-21

Mev

-

.I.

4.6

Mev

G

o - -

- 125

xw

1-1

000

---

9-8

n

LO

W m

ergy

8.9

mg/cmC

Ele

ctr

on

s>l0

0 k

ev

75 k

ev

ACI

-.

.C,l

42

LCRM

1-1000

13

Photo

- A

lum

inm

c

~'-

at.

er

; m

ult

ipli

er

n =

.04

5 s

ter

LCRM

~o

o-~~

xI, 000

12

-_

S

urf

ace

1).

3 m

g/cm

Ir

oto

ns

0.3

8-2

.9

Mev

0.

37

Mev

0 =

.0

45

2

LCW

i 1-1000

14

&rr

ier

Nic

kel

GO

= ,0

0113 c

m

2 C

ph

as 2

.6-6

.0

Mev

2.

58 M

ev

An =

,0

66

cm-c

ter LC

RM

1-1

00

0

15

2

ts0=

.00526

c!n

2

*-

Sh

ield

ed

4.

4 gm/cm

~R

ay

s

1-3

Mev

1 M

ev

4.25

cm

2 LC

1?

1-i

M0

2

Ganma

3 M

ev

LC

hl

130-1

60,0

00

-F

-

7

- 13u

al0

mm

-2

&cm

2 X-Fays

25-2

50 ! %..-

- 69

cm

LC

*&..

10

-10

,00

0

(2 a

un

t 2 r

y-T

cay6

.2

5-0

.6

Mev

S

ca

les-

16

64&

1024

8-

3

y-R

ays

0.6-

1.3

idev

-p

my

s 1

-2 M

ev

prU

nye

2-3

.7

bkv

yR

ay

s 3.7

-6.0

~

ev

C

osm

ic R

ays>

43 M

ev

6 M

ev

Figure 5 - Varir ion of subcarrier oscillator reference frequencies e t h temperature in s pre-launch calibratior;. .41sc shown i s the calibratim of a typical tkrzistor chamel.

Figure 6 - Calibration of a typical 1ogarithm.t~ c a t rate meter (IcRM) at -i&s teqezatures.

pl.ovides a m c each rotation about the intended spin axis, which is

vertical in Figure 1. The latitude sensors, Fhvre 8, are marnted at

various locatima on the spacecraft as shown a Figures 1 aad 2.

one of these sensors pro&ces a m e each spin rotation, the =tilt

king identified by -5 tipe aad polarlty of the pclses m the telenetry

record, chunel 1. T b i s prorlder an indicator, vithin a 22.5' interval,

of the locatian cf the solar vccter w i t h respect to t he latitude plane

of tke satelUte. On the a$-18, muever, the hterpretation of the

aspect data is ctmsiaezably ctaFuseG oecause the sa te l l i te did not

rcPain spinnitg about its intentled axis.

The reeaining 13 pain frame and 9 subcolanutator chaMels are given

to data f'raa the scientific i n s t n ~ n ~ ~ t a t i c n .

Detector Canpl~nrmt

The detectors ill the OFG-111-3 an? indicated on the block diagram,

Figure 3, and m n y of their properties, telemetry modes, and channel

a s s m t s in Table I. Table I1 contains a list: of a l l ' t he ERS-18

seksors, a sumaary of tenahol3gy appearing in various documents

describing the project and its results, and the relaf2onship of the

detectors CQ the two satel l i tes . The f o l l w h g sections describe each

radiation counter in some detail .

A caaplete discussion of the respglse a d of the detectors which

are cam& to the E3S-17 i s included i n the f ina l report of that series.

Rvther details 0.f the properties of the EX-18 detectors w i l l be h-

cluded in subseqient reports.

I I /

TYPE

LSX

N-?

-I;

MER

IDIA

N S

ENSO

R

Fig

ure

7 -

Con

stm

ctio

n o

f th

e m

erid

ian

so

lar

sen

sor.

T

his

pro

du

ces

a si

ng

le p

uls

e ea

ch r

ots

tio

n

abou

t th

e sp

in t

rxis

, in

ten

ded

to

be

pa

rall

el t

o t

he

sli

t.

.,r?r

r - rn

r-,.

-!~

p-a

:~r*

, .*

--Z

WW

W :A

*EQ

~ KW

&?

WP

WT

WJ+

~- CI---.UY.---YI----..-LII

, ,

.* A..

rP

AN

EL

MOU

NT

SENS

OR M

OUNT

- ?//- LS

X 60

0 N-

P -N

SIL

ICON

LI

GHT

SENS

OR

SUN

SENS

OR A

SSEM

BLY

T YPl

CAL

Fig

ure

8 -

One

of

th

e ei

gh

t la

titu

de

sen

sors

. O

nly

one

sen

sor

pro

du

ces

a pulue

each

ro

tati

on

, d

epen

dh

g on t

he

eo

hr

dir

ecti

on

wit

h r

esp

ect

to t

he

epin

ax

le.

Det

ecto

r Q

uan

tity

In

etn

un

ent

Men

omic

M

easu

rem

ent

boa

rd-

Rel

atio

n t

o E

RS-

17

Det

ecto

r

Mer

idia

n S

ola

r - -

Sp

in R

ate,

I.

1 S

enso

r

LP. t

itu

de

Bur

, S

enso

r

Su

rfac

e B

arr

ier

SSB

m

rtiz

le D

etec

tor

Li-

&ri

fted

%

SD

Pa

rtic

le D

etec

tor

Low

-mer

gy

scwZx

PM

Pa

rtic

le D

etec

tor

Gt i

tud

e R

efer

ence

So

lar

Lat

itv

.de

W.R

.T.

Sp

in Axla

I R

epla

ces

Sim

ple

So

lar

I R

efer

ence

S

yste

m

Ele

ctro

nsf

iO

kev

en

er~

fy

3

Sm

, e

xce

pt

new

m

ount

X

-ray

s 1-

14 A

P

roto

ns

0.38

-2.9

M

ev e

ner

gy

1

New

D

etec

tor

pp

art

icle

s 2

.6-6

.0

Mev

Ele

ctro

ns>

O.S

M

ev

ener

gy

1

Sam

a a

s p

rev

iou

s SS

D

Pro

ton

s 7.

5-15

M

ev

ener

gy

Ele

ctro

ne>

10

0 k

ev e

ner

gy

1

Sim

ilar

to

Previous LEP

M,

F~

oto

ns 3

-27

Mev

en

erg

y

exce

pt

smal

ler

soli

d angle

Sh

ield

ed G

ams-

Ray

S

hie

lded

G

anm

a rs

rys

&id

ch

arg

ed

1

Sim

ila

r to

hig

h e

ner

gy

Ph

oto

- C

ou

nte

r G

am

~a

p

art

icle

s, 1-

3 M

ev

pil

tlp

lie

r d

ete

cto

r (HEPM)

ener

gy

lo

ss

exce

pt

for

pas

aiv

t sh

ield

ing

Gtu

una-

ray

Co

un

ter

Dua

l G

amna

G

a~

r~

a

ray

s an

d ch

arg

ed

1

pa

rtic

les,

.25-6

Mev

en

erg

y

loev

Sim

ilar

to

Pho

awic

h S

cin

till

ati

on

Ca

mte

r on EM-17

- * S

oli

d S

tate

Det

ecto

r m

ar

Ene

rgy

Ph

oto

nn

iLti

pli

er

(A) Geiger-Mueller ~ a u n t e r s ( ~ - M )

The Geiger-tube detector system was designed t o measure very low

energy e l ec~ rons and solar X-rays. The threshold sensi t iv i ty of these

thin window HN 6213 Geiger tubes is determined by the wbdm thickness

2 a c h was 1.2 mg/cm of mica. In order t o make a neasurement of the

amni2it.ectional flux of these part icles, three Geiger tubes are needed

which have non-intersecting f ie lds of view. The t o t a l solid angle i s

agproximately 2n steradians. In th is case the Geiger tubes were mounted

along three mutually perpendicular axes and res t r ic ted each t o a i 45'

conical f i e ld of view by an aluminum c o l l i m t ~ r . Fikure 9 i s a drawing

of one of the assemblies, a l so visible on the s a t e l l i t e ;hotogra~hs,

Figures l a n d 2. The outputs of the three tubes are telemetered, both

individually through logarithmic carnting ra te meters (LCRM) that cover

the range 60-60 kc, and suxmned through a single binary scaler, t o another

60 kc LCRM as shown in Figure 3. T h s the range covered for the sunmaed

outplt i s 120-120 kc counts/sec. In order t o measure the verr lowest

casting rates , the swmed output is a lso connected t o a scaler-adder .

c i rcu i t , which covers the range 0.5 t o 10C counts/secmd.

The tubes are sensitive t o X-rays between about 1-14 f and w i l l

detect solar X-rays even when t h e sun is quiet. Since the sun i s

effectively a point source i n the Geiger tube apertures, and the only

such strong s o w e , the time structure of the Geiger tube responses

can be csod t o gab an independent measure of the aspect of the s-ce-

c ra f t r o l l axis with respect t o the sun. This r;Uars a more rel iable

Figure 9 - The surface barrier detector for counting low energy protons and *particles. This i s incluJed in the same mount as one of the G-M counters. The remaining two G-M counters are m t e G In the arsembly shown at the top apex of the tetrahedron in Figures 1 and 2 .

estimate of the radiation f l u e s emanating from the sun. Since the bulk

of solar X-rey e m i s s i ~ ~ i s -a t low energies, the Geiger tubes are the only

instruments on t h i s s z t e l l i t e t o provide measurements of quie-t so1r;r

X-ray enLssicPI. Geiger tube data a l so provide important complementary

i n f o m t i o n t o the counting ra te data from the other it~struments during

disturbed periods of solar ac t iv i ty .

Because of the thin windows, the G-M counters are sensitive t o low

energy electrons when inside the magnetosph~re. When in interplanetary

space, and outside the view of the sun, the backgr-5 ra te is ddeer-

mined by galactic and solar cosmic rays.

(B) Li-drifted Part icle Detectar (SSD)

The s i l icon solid-state detector t o measure low envgy electrons

consists of a lithium-drifted cube of si l icon of dimensions lxlxl mm

operated a t a 75-volt bias. This detector, shvm in Figcre 10, i s

mmnted under a hemispherical 10 m i l aluxinum shield on one face of

the s s t l -U i t e (lower r ight hand periel of Figure 2) . This design has

been evaluated on the TRS-I1 s a t e l l i t e and has been shml t o be almost

an ideal 2n geometry. The outpit of t h i s device i s amplified and fed

through two pulse-height discriminators, one which t r i g ~ e r s on pulses

prodticed by 180 kev energy losses in the detectar w.2 Ail be measuring

mainly electrons above 0.4 Mev. The other discriminator w i l l "rigger

on 2.5 Mev energy loss pulses and w i l l be loeasuring protons in the

energy window 8-21 Mev. The otityt of the electron discriminator is

fed t o two LCRM's, one a low-level meter wi th a range of 1-1000 counts

L I DRIFTED §I DETECTORg-\ f

HEMISPHERICAL SHIELD 10miI A l .=0 .068gm/cmL

Li - DRIFTED PARTICLE DETECTOR

5 m r e 10 - The sol id state Cetector assembly consists of a 1 mn S i -- detector under a 10 m i l Al hemispherical shield.

per second and the othe- s high-level meter with a range of 3CO-300 K

c w t s per second. The low-level meter i s prezeded by a one-shot mul t i -

vibrator, so indivi&r:sl counts can be observed during the sample period,

if the courting ra te should be lass than a few per second. The output

of the proton discriminator i s fed t o a LCRM with a range of 1-IK counts

p r second preceded by a or2-shat lnultivibrator for very 3ow count

3 rates. The t o t a l range is then bet,er than 1-10 counts/second.

(c) Surface B s ~ r i e i Part icle Detectcr (SBD)

The surface barrier detector i s fiesigned to nieac=rre very low encrgy

protans in the outer w.etosphere and beyond. The sensing element,

show in Figure 9, has a sensitive thickness of 19 microns. The ])roton

discriminator vcltage bias level i s s e t t o measure protons in the

energy range 0.38 t o 2.9 Mev. However, a riickel wbdow of .0000610 inch

thickness was a?ied so that the SBD will not respond t o l i ~ h t fron tb!

sun. The alpha-particle energy range i s 2.6-6.0 Mev. A preamplifier

c m p t i b l e with the SBD and manufactured by Solid State Radiations, Inc.

i s used t o drive the main anplif ier . Amplifizd pulses passing tile

alpha discriminator drive a 1-1K cps LCRM which i s read out in telemetry

channel 15. Paises passing the protm discriminator are scaled by a

factor of 16, then read in to telemetry channel 14 via a 1-li<C LCRM.

The 1-1KC LCRM have the characterist ic that individual counts can be

seen through the telemetry which permits read out of very law counting

rates.

(D) Low Wergy Par t ic le iletector (LEPM)

Thfc instrument is designed t o detect low energy electrags and

protons. A s showr!. %1 Figure li, it consinta of a 0.1 cm thick by

1/4-inch diameter p las t i c c rys ta l cemented t o the face of an RC.4 4460

photmul+,iplier tube operated a t 1200 volts . A conical eol l ina tor

w i t h an e x i t aperture of 0.4 cm dianete? and hal f angle 7' is covered

by two 0.55 m i l aluminum f o i l s . Shielding in a= other direct ions is

2 i n excess ~f 2 g/cm . The discriminator will t r igger on 75 kev energy

loss pulses. This a_. izctor , therefore, measures incidext electrons

above 100 kev. The s ignal condltfoning e l e c t r m i c s are s imilar t o the

electron chanr~els of the so l id s t a t e detector. Output appears i n

telemetry channel 13 fo r the l&r-levzl ' TRM, and in channel 12 for the

high-level LCIU4.

(E) Shielded Gama-Ray Counter (shielded ~ama)

This sc in t i l l a t ion detector i s designed t o seasure 1-3 Mev gama

rays m3 charged pa r t i c l e s producing energy l o s s t s in t h i ~ range. It

consists of n 1.91 cn. long by 1.91 cm. diameter N ~ I ( T ~ ) scin.til~.ation

c rys ta l encased in a ruggedized mount and further : ielded by a carbon

cylinder 1.75 an thick, a s shown in Figure i2. The c r y s t a l i s op t ica l ly

connected t o ar! RCA 4460 photomultiplier operated a t 1200 volts .

The output of the PM tube is fed t o a single-channel analyzer.

This analyzer corisists of ar L?per and a lower discriminstor which pro-

vide inpclis t o an exclusivr OR c i r c u i t , Only those yu1.f; which corres-

pond t o an energy loss of 1-3 Mev a re counted. The m.,put r a t e of the

ana lpe r is measured with two LCW.'s whose ranges are l - l K and 100-100R

cps , respectively . 7 - *

$ Gamm-ray Counter (h~sl j 'I'his detec.;or is used p r x m i l y to obtain a m e m t of the

cosmic --ray tlux vi th anti-coincidence rejecticm of charged pa,-ti-

cles. Its cena& p.zt ccmsists of a h r g e I O ~ I ( T ~ ) crystal, 7.62 cm .?

I in disaeter by 7.62 cm long. Su,rmuding it on all sides t u t one i s s t

bucket-shaped s h ~ c l d c4 pzastic s2inti l lator. The tuo scinti l lators

are optically separate. e ~ h is viewed by its oun RCA 6461 photo-

multiplier tube, as shown in Figcre 13. The shield is designed pri-

nrarily t o reject counts in the central detector caused by cosmic rays.

Any charged cosmic ray traversing the cent- crystal n u t aLso pass

tbraqh the shield, producing an anticoincidence rejection pulse. In

order t o determiae wkther the anticoincidence was h ~ c t i o n i n g properly

and also t o increase the infomation yield of the instrument, i, uss

deswed to be switched cm and off every Pour telemetry cycles by the

sa te l l i te clock, giving central detector counting rates with and without

charged particle background.

There are a t o t a l of eight telemetry channels associated with this

detector:

Channel (16) Central detector counts with energy greater than 25 kev. Output is a 10-10 K cps I ZRM without one-shot.

Charnel (8-3) Central detector counts v i t h enera- between 250 and 600 kev. Output is quasi-digi+xdwitk s prescaling factor of 64.

Channel (8-4) Central detector counts with energy between 0.6 and 1 Mev. Output qmsi-digital prescaled by 32.

* Quasi-digital definition fcllaws 1ist.ing.

Channel (8-5) Central detector carnts with energy between 1 and 2 Mev. Output quasi-digital, prescaled by 16.

Channel (8-6) Central detector counts with energy betveen 2 and 3.7 %ev. O u t s t quasi-digltai, prescaled by 8.

Channel (8-7) Central detector counts with energy betwee, 3.7 and 6 Ekv. Output quasi-digital, presCtLled by 8.

Channel (9-6) Cmtral detiector counts w i t h energy loss greater thao 6 Mev. Effectively all counts due t o cosmic rays. h t p u t via 10-10 K cps WRM with me-shot.

Channel (9-1) Shield counting ra te . Output via 10-10 K cps LCM with me-shot..

*'Quasi-dQital" means the folloving :

The detector pulse ra te i s first scaled t o obtain the prescaling factor indicated. Part of t h i s otit-t i c then scaled by m a d d i t i a a l factor of 16 ssd which is added in a resistftnce network. The r e s a t a n t 4-level s w i s tsansmitted as an analog voltage. This method increases the dynamic counting ra te rarrge by an order of -.itude.

Table I contains a camplete s m cjf the ERS-18 detectors. For

each detectar, the principal radiation m e a s u , r : and i t s energy q e ,

together with appropriate instrumental and telemetry deta i ls are list&.

The abscrbcr l i s t ed for the Geiger tubes, solid s t a t e detectar, and low

energy photamltiplier is in the direction of the sensitive aperture;

over the remining solid angle shielding is several gm/cm2 for each instru-

ment. Abscrptim for the higher energy 2etectors is an estimated average

over the detector and sa t e l l i t e masses. The actual se',tlqgs of each

discr-tor level, calibrated prior t o f l ight , are alsc, given.

Bach Geiger c a t e r selected for the EFS-18 has been c a r e . W y

calibrated; the effective forward area is about 0.356 em. The approxi-

BLEE

DER

STRI

NG

PHOT

OMUL

TIPL

IER

';I

TUBE

RCA

446

1 5 A

I I

NaI (

TL) C

RYST

AL -

1

I P

3%

r 2.5

0 DI

A.

I

i h L

HARS

AL H

OUSI

NG 0

.030

"

PHOT

OMUL

TIPL

IER

TUBE

RCA

446

1 --

- - t

Y - R

AY C

OUNT

ER

2 F

igu

re 13 -

Th

is G

nmna

-Ray

co

un

ter

wit

h g

em

try

fa

cto

r fo

r an

is

otr

op

ic flux o

f 69

.5 c

m

oper

ate6

ove

r th

e 25

kev

to

6 M

ev ra

nge

. D

irec

t p

art

icle

ei

.fec

ta a

re r

ejec

ted

by

the

an

ti-

co

inc

ide

nc

e

shie

ld.

mate solid angle is given for each d e t e c t ~ r as determined by meesuremcnt

or calculation. Efficiency-geanetry factors, Go, for an.incident flux

i~ot ropic over h solid w e are also given for the directicmal detecfors.

These have also been obtained by mcaslwment and cdlcubtion, and may be

energy dependent i n S ~ I E cases. For the hfgher energy scintillation

counters, Go is obtained the foraa;lla

where D is the W t e r and L the length cf the right cylindricail sensitive

Sate l l i t e -,'.erctions

Launch and Orbit

The EZ@-18 was launched on April 28, lg7 dcng with the I;A u d

~ E I Vela Sa te l l i t es in to a highly e l l i p t i ca l orbit. The i n i t i a l orbi ta l

parameters were 117,600 kilometers apogee and 15,'JOil kilameters p ~ r i g e e

L-om the Earth center; t h i s resulted in a period of 47 h m s . The semi-

nmjor axis was inclined about 12. 'jO southward from the ecl ipt ic plane

and was about 120' from the earth-sun l ine . Inclination of the orbit

plane was 34.b0 t o the earth 's equatorial plane. Figures 14 and 15

show projections of the orb i t on Jlme 20, 1967.

Spin-up was o3tained fran a coiled spring separation mechism

located in the shroud of the missile system. I n i t i a l spin ra te was

close t o 6 rpm, as determined fran the receiving stat ion AGC records,

and the periodicity of the gelger counter rates as they swept by the

sun.

Alttaugh the s a t e l l i t e w a ~ dynamically spin balanced it did not spin

about the intended axis. I n balancing the s a t e l l i t e the additional

weights were not placed correctly t o maintain the intended spin axis as

the principal axis of ine,rtia. Consequently, inmediately a f te r ejection

the t i p off errors caused a pecessional motion about the original spin

axis which did ro t damp oat u n t i l a new s 3 h axis about the p rkc ipa l

nornent of iner t ia was es'tablished; t h i s occurred by mid-June 1967 when

a pure rotational motion was observed. This f i na l spin orientation, a s

well as that during +,he transit ion period, have not yet been determined.

ERS

- 18

ORBI

T JU

NE 2

0-22

, 19

67

ECLI

PTIC

PLA

NE P

ROJE

CTIO

N

Fig

uze

14

- The

Jun

e 2

0-2

2,

1967

orb

it o

f th

e E

RS-

18 pr

ojec

ted

an

to t

he

Ecl

iptl

c p

lan

e on

th

is

da

te is

sho

wn

bec

ause

ex

ten

siv

e re

du

ctio

n f

or

this

per

iod

was

pe

rfor

med

in

itia

lly

.

ER

S-1

8 OR

BIT

JUNE

20-

22,

1967

SO

LAR

- MER

IDIA

N PL

ANE

PROJ

ECTI

ON

Fig

ure

15 -

The June 20-22, 1967

orb

it p

roje

cted

on

to the

X-Z g

lan

e

in S

ola

r E

clip

tic

coo

rdin

ate

s

Tracking and data recovery for. the ERS s s t e l l i t e s a r e performed

by the 8 W System of the Nat!.onel Aeronautics -\d Space Administration.

Data vas acquired a t 1422 soon a f t e r launch on Apri l 28 x"rm the s t a t ion

at Johannesburg. Analog magnetic tapes recorded a t the v a r i m s STPDAN

sta t ions a re f i r s t sent t o Goddard Space Flight Center (GSFC) f o r

qual i ty control a rd evalubtion and then t o WSD f o r processing and re-

duction. In addition, r e d time quick-look Sanborn char ts recorded a t

various s ta t ions permit GSFC and TRW personnel t o evalxate s a t e l l i t e

operation on an us-to-date basis. The tracking and data acquisi t ion

( 3 1 plan is describecl i n the ERS-18 operations p?-ar. dated March 1967 . Refic. --I Zyhemeris q e t i c tapes a r e a l s o proviCed t o UCSD from GSFC.

Data Reduction System

The reduction system a t UCSD i s nearly ident ica l t o that used f o r

the BS-17 s a t e i l i t e , with minor modifications fo r the ERS-18 format.

Analog tapes recorded a t 7.5 ips a r e played back a t 30 ips through the

system shown i n Figure 16. The voltage output of the subcarrier dis-

criminator produces the Sanborn chart , shown i n Figure 4, which a l s o

has timing and control indicators. The output voltage is sauyled a t

a high r a t e with an I l - b i ~ analog-to-digital converter, whose outpu':

is accumulated in a w e t i c core memory. T h i ~ is dumped In record

format onto a computer-compatible magnetic tape f a r a~itomat \c r educ~ ion

and analjrsis. Timing and tapc speed compensated f o r the en t i r e system

i s obtained from reference channels recorded a t the STADAN s ta t ions .

Further d e t a i l s and opere t ima l procedures of the system may be obtained

(2) from the e a r l i e r report .

. ., J -d

2 6 w

0) m +,

k r i w i P I

A control or I . D . cbrd i s punched fo r each continuous recor :ed data

l cngth which cons t i tu tes a f i l e on t h e i n i t i a l compuLer tape. This card

contains an 1.3. n u h e r f o r the f i l e , acquisi t ion and piayback da tes , deta

s t a r t 6 - fi stop t i nes obtained from the Sanborn char t system, ca l ib ra t ion

Ja ta , e t c . These cards a r e cont inual ly checked, corrected and ~ p d a t e d ;

a l i s t i n g forms a mr:;er record of the data . These cards a r e a l s o

issued a t various stages i n t he computer reduction.

The flow of da+a through the en t i r e reduction system I s shown in

Figure 17. This has a l s o been rlescribed in d e t a i l e a r l i e r . Dig i ta l

tapes a r e f i r s t edl-czd t o de tec t obvious e r ro r s , remove f a u l t y playbacks.,

e t c . , and then are stackeL in general chronological order 0.1 a cleaned

up bi?ary tape f o r the f i r s t d e c o m t a t i o r . This iiecormrutation u&?ra-

t i on recqguzes main frame and subcommutator sync, se;~rat;es ovt the

various chardels, reduces each sample t o an eq iva lex s u b c ~ l r i e r

frequency, and produces a ntiJ magnetic tape with the &ta in F s h p l i f i e d

format. This tape i s then prec ise ly ord?re$ and edi ted t o eliminate over-

laps , and is used t o obtain quan t i t i e s scc., a s c m t i n g r a t e s , tempera-

tu res , voltages, e t c . They a r e r ' cted t o polynomials L! subcarrle2

frequency a t each fuemperature ca l ibra t ion of each channel a s indicated

i n the Appendix. This dsti; may then be p.Lotted channel-by-chriiilti vs.

time, or m y be merged ~ 5 t h o r b i t a l data f o r s more complex ana lys is

procedure.

Sa t e l l i t e Operation

No indication of a major s a t e l l i t e fau l t has been indicated f r o m

the GSFC quick-look data, therefore tracking ane data acquisition con-

tinrled a t a h igh level of coverage throughout the opereting l i f e t i r e

of the s a t e l l i t e which ended on 3 June 1w uiien the timer caused tern-

h a t i a n of the radio transmitter. w . e t i c tapes are received in ship-

mects from GSFC a t a m e t o two wmth k g a f t e r recording. A log book

entry i s made for each tap from wfiicn selections of data t o be reduced

can be made, and the related c m t r o l 1 . D - c m generated. Abmt 23.90

malog +apes b ~ v e been l i s t ed in t h i s 1%. This represent; about

6CW 1 .E. 's, sane 7203 hours of r --,a a d I ,Z t e a r l y camplete sa te l -

l i t e orbits . The useable caverage ob+Zaked on an orb i t a l basis is

about 7% and is shchn ?or each orbi t through h r c h 26 in Figwe 18.

Coqle te data has x-u been obmined t h r u u ~ or?~.'_t i.9 or: 8 May; the

le+,cst tap is f m orb i t 200 on Mqy 25.

The s a t e l l i t e is near apogee nost of the t h e , hence ar; Large

distances,-18 R s tat ions w i t h antennas fiaving g a h s greater tbm e

abmt i9 c?B acquire the & c i t y 9f the ata. For eicamr?'t, Johmesburg,

v i t h ar. 85' dish, has obtained over 500 analog tapes.

I n order t o evnluate the s a t e l l i t e i x t runen t p e r f ~ ~ c e in ad-

vance of f . f l p l syack operations, selected -wrtions of the data rave

beerr playec! back an& reduced trscrilgh the f i r s t decomiitation. Tbis in-

cluded 78 I . D . ' s , reprecenting over 143 hmrs of dafs from e-req- seccnd

pass and 5 'tittered over aost por5ions of zce ozbit. This e v a l u a t i ~ n

included the f l r s t 8 months of operation, through orbi t 116 m December

1 1 Ir. eddition, orbi ts 26, 27 and 28 have been completely re-

duced in o.+er t o provide an assessment of ins t rment operation -mder

a l l radiation enviraurrents normally encountered by the s a t e l l i t e in i ts

orbit.

Based on an e idua t ion of the sa-qle playbacks, the operation of

,he sc ient i f ic instruments was about as expected. As of 3ecembcr 14,

1967, m a n d i e s and fa i lures have been noted only in the operation of

the Geiger Camters. Two of the G-b! c a n t e r s had fa i ied by the beginning

of Nw-mber 1%7, based on t he i r lack o r respofise t o e i ther so la r

X-radiation a r trapped e1ectm.s near perigee. G-M No. 2 sDuge0 a

reciuceii respzzse m. October 6, md by Novsber 9 it ilo longer registered

c ~ w t i r i i . G-K No. 3 was l a s t obserred counting on Auwst 20; by

September 26 it had becune imperative. G-M No. 1, however, was s t i l l

ope l~ t i ng a t IU or nearly f'ull efficiency an December 11, 1%7, based ~ ~

on quick-look data decommtated a t UCSD. Dsta received from the Ram

Tracking Sta+,im showed it iit operation u n t i l $he end 05 the satel-

l i t e ' s telemetry l ifet ime on $me 3, 1%:. Failure of these i n s t r u e ~ t s

i s l w e t cer-ainly due 50 lose of the t ~ b e s ' gas f i l l .

The solid s ta te cie~cctor proton channel ( 8 - a ~ e v ) has so f a r

cmted definite ra tes only & k g the r o b prcton events of May 23-30,

1967. This i s probably not ar~abpalcua behavior since mder norm1 con-

2itior.s the s a t e l l i t e never &?counters ~r0tar.s of t h i s energy. ~h~

r e l ~ t i v e l y t.eh perigee of 2.5 R i s sdtsid? t h e i r ze r radiat.ion b e i : ~ . e

All the remaining radiaticm detectore appear t o have operated

properly and showed no indication of failure, or altered response

tmqh the m t i r e time span co~ered by the quick-lock checks.

The temperature of the s a t e l l i t e structure was ordinarily 8' C

and had not changed by -are tbar? b0 C during the f i r s t a m ~ h s of

Preliminary decanmrtation indicates that the reference frequencies

in channels 8-1 and 8-2 have not changed by more than f 1 hz between

bky 3 81id October 10, 1967.

A s already indicated, the s a t e l l i t e is s3!ming about some un-

e,speted axis. hreliminary evaluation indicates that t h i s axis can be

located and its direction in space b fe r r ed u i t h encnigh accuracy t o

permit interpmtatior, of ccruntixqg rates f i a n the directio::al detectors.

Based on the results of the spot analysis, the s a t e l l i t e end i t s

instmnents &ire perfomed remarkably well. The few can-catastropic

anonwlies can be compensated for in the data analysis. The sa t e l l i t e

cle=ly praduced significan-L new on the trapmC radiation, w e t o -

spheric particles, solar m d cosmic X-rsy and ganme rays, and galactic

C O ~ ~ C - F A Y S . Therefore reduction of significant p r t i o n s of the

entzxe mass of data i s proceeding.

Status of Redcticn and h d l y a i s

A s part of the i n i t i a l evaluation, orbits 25, 26 and 27 hbve beec

completely played beck, e&ited, ordered, deccamrmtated and instranent

can t ing rates obtained frtm tile transmitted sibcarrier frequencies.

These r6tes have been hand-plotted resulting in a s e t of sane 70 graphs

on a lW/hr. basis covering the interval fran l&O 17 June t o 1800 23 June.

This s e t includes orbi ta l plots and much of the quasi-digital data from

the anticoincidence ganuia ray counter. The presentaticrn and discussion

of Chis Cata w i l l form the substance of the second r e p r t in th i s series.

Most of the ciata from launch u n t i l orbi t 17 on b y 3 ,has a l so been

played back, .d i s presently unde?-going editing, ardering, and decan-

mutation in p: eparatim for automatic plotting. T h i s interval includes

the May 23-2' , 1$7 ser ies of solar events, whose solar X-rays and

rear-earth par t ic le effects were extensively observed by the ERS-18.

mta playback on selected portions of the relcaininr data w i l l resume

soon.

Technical re lpr ts and published resul ts may be expected on the

following topics :

(1) Ptesentation and d i -c~ss ion of the data from the o rb i ta l

series 25, 26 and 27, a s indicated above.

(2) Analysis and mbllcation of the May 1967 series.

( 3 ) Ffesentaticn of data obtained in the f i r s t month of s a t e l i i t e

operation.

(4) Analysis and Publicatign of results on cosmic gansna rays ob-

tained from the EPS-17 and 18.

( 5 ) Presentation of data obtxined c?uring sc iar proton an6 X-ray

event;.

( 6 j ~ d d i t i o n a l resul ts on cosmic X-rays, tragped radiation, mag-

netcspheric toundary phenomena.

C A L I X t A T I ~ COEFFICIENTS

This appendix contains the coefficients from a l eas t squares

polynomial fit of the counting ra te vs . frequency curve for the ERS-18

instruments a t eight different inst-nt temperatures('). The co-

eff ic ients actually represent the logarithm of the counting rete as a

h - c t i o n of the actual subcarrier frequency minus 1200 zps, thz IRDC-

channel 5 lower band edge. ERS-18 Channels 2, 3, 4, 5, 6, 7, 9-6,

9-8, 10, ll, 2.2, 13, 14, 15, 16 have s s e t of coefficients for temper- -

a%ures -25. -15, -5, 15, 25, 35, 40' C . Charnel 9-1 has coefficients.

f e r t e m p r a t u e s 5, 15 and 25' C-*.

' ih is appendix i s ~rganized by telemetry channels. Tne channel

number, a short description of the detector, and the dynamic counting

r a t e rarr ~f the c-e: head - ,ch page. The different temperatures

are shown k the co1-~nm nrarked "W". The coefficients are .in floating

*in% decimal format, v i th the power of 10 following the l e t t e r "E".

The c o l m heeded "code" i s a rep?+;ition cf channel number and tempera-

ture, aqd can tahs same data used f a r editing. The entries of the

form "DATA (CF(N) = " are FORTRAh' statements used for computer calcula - t im of counting rates.

A counting ra te i s calculated a s a polynomisl function of frequency,

the coefficients for which are specified by the channel number and

temperature. Actup.1 teleme tered frequencies 1 i e between 1200 end 1400 cps ,

but the input irequencies used i n evaluating counting ra tes l i e between

0 and 200 cps. The resul t cf th i s operation is the natural lcgarithn

of the countkg rate. The general equation is:

c = exp (bo + bl f + b2 f 2 + - - - + b n P )

where c is the counting ra te

bn i s a coefficient

? i s a frequeucy between 0 end 200 cps

n is the n - i e r of terms in the expansion

Typical s a t e l l i t e operating temperatures do not reIm?n obligingly

a t me of th.? eight calibration temperatures. Accordingly, the reported

counting ra te from a.detector i s interpolated l inear ly from the ccmting

rates calculated a t the two nearest calibration temperatures.

TFMP C O E F F l r I E N T S CODF

n a T f i ( C F l l ) = 1 -1004QP4474272E O l r 6.~,518070659bE-01r-1.367R7380786E-02~2 40117 Z r 1 ~ 9 4 8 2 ~ 7 1 4 2 3 9 E - 0 4 r - 1 . 7 8 * 3 9 9 4 S Z O 5 E - O 6 r lr0222SC88858E-0802 40127

3 r - 3 0 2 9 9 3 0 3 5 8 7 0 6 E - l l r 4a551165359Q4E-14) 0 2 40133

CKAYNFL '3 5HD GAMMA (130-1Or)KC)

T FUP

4 n

CHANNEL G GM NO. 1 RELLYRAND

CODF

CHANNEL 5 GY NO* 2 APEX

(PI

kLISZ-$PSI-3900ZE969EZLm9 fiZI-36~L961S15Z6'9-b60-IGZEOil~069~Oe~ ' . r

EPICZ-90LO-3606S60LOGiQmL-~~Oa3*69SL~~O~Lm bzU-32156L1999Zi*I-' e L11SZ-9010-36~S?9LL9bLCm9 '13 ~~LIP€?Z~~ZI'Z-.PO 3*9~0£66EI69*Z I

rtbrr)jJ)VAVQ kC-

lC 1st-93 (bb-31Z906?9t1Ue'F-bI~-~t6YZ09500LY*E E €2~51-9080-3£~ES69900tEmI-~9C-3AQQbZEJ.LL5mZ bf~-3LSi95LLEL€ZmZ-* L ~IlSK-90EO-3f€61LQQLS?6m9 bT0-368S6L9Z6@ZCmE aIO 3t68€09fO€S9*.Iy I:

alCSt)jJ)VAVO si-

Lt lL. 9C IEI-31S6S69USL00mZ '01-i.0f*6Zi€EZOSeZ-' E. tZSL- 9000-38SU6€L66&~Z8~4 bS0-39011L9Z6Z9U'Z-*tO-31603LS6BOUCmZ Z tIl5- 901U-389"96*056Z6'1-b00 3ZZ06SZSZ~SOe8 '20 39LfOL*EL\l@mI- I

~(L*~JA~)VAVQ L - I 90 (LI-36BSOEY096LO*0 ' 9

DtI5 90EI-3069EE~iOb€LO'~-b~I-~€Ih60960€6Z'5 bYO-3*EBSSIIlE9Swf-b € fZI5 3090-3€91iE?OV*CC"i m90-38Zb)11S61€9mE-*ZO-3LS59695LB9C*Z L I YOOO 3Qb:€€691U*SmI-bI0 3€160Z6*LIFPm* '20 39S53o69LZZIm9- I

r (Ltt)dJ)d!'3 LS

€€IS1 90 (V1-30LHbIC9fL66'9 "Il-3~8&tC*96L6f'*-~ 5 €Zt?~1 9080-3~Z6599*%PLL*I b90-3CCtr0~50166mE-bto-36~ILZZ98S6?rmS ' Z 61161 9020-33L@LE6StSl9*9-W 35~OLOQC09ZZ'Z '19 366C€6EbSWZ'*- P

~(bZt)jJ)YAV3 b;

€nfCZ OG (SI-~CIL~Z~JZL*QEZ*~ bIf-3SZOSEb69%3Zm8-0 E cTICZ 9GUO-;Z9i)LI3LWi-E 490-3btQIZLG96L?C9-btO-391bf4S59ZC01@ ' Z hltL?, 90ZO-3Z9SC9ZIZS66eS-'90 3!a9SL0595SES0Z byO 30T669ISOStL'*- 1

st tF$Jj2)k'lYO C L

LE~SE 90 ( II-~.VESCLL~+LZL~~ bOf-36L!LT?C'#F 10*I-b E SZtLL 9CUO-3899L9Z6G0LZmt b30-3Y~I~6900@L5C9-b~O-3ZIL150~OB?~'0 Z £11S€ 99ZO-3Cf?Z*QTOf99*S-"00 3€t@CL6%C8tZmZ b10 3llL9ZIIOQ!Cb€- l

mlLlk)A3JVAV0 bC

*VIO, 90 (LI-~~CO~L~OY~LL*~ 9 ?€lot 90QI-38G869CI~O~OQ9-011.-26J~Z6~bb~9?L*Z b60-31'X*€5b@tll"&,-b f: 52109 9093-3600fZfCb08ief 4?O-3~t*t9S~f69bC1m'€O-3Y~~f LLZICQi6'8 Z *IlQ$ 3010-39LbGQb916C**6~610 3PS~OEOXOii0Om? *ZO 3S61Cb)~C1LQOUI- I

~taa~:~a:v~ro

(9 LLThZ bo%l-3lZiL09t~Z9O'Z-'Z1-36~*iII$9b~LX'Z *OI-3YIYSS9L808LL6-* L EZTSZ 86LO-36161f*O€!?E?*L *i0-3f58ZPES19t9mi-Lf0-36ZLZO$€ZZSE*E Z i1157 P610-3f5;EE89tiEf8*I-'OQ 39?21L296209*G 'IC 3IUZ09*LL06Z*L- K

=(ZfilA3lVLVCl

CWAWhFL 13 LOW ENERGY FtFCfRbFI !I-!KC;

Temhcbl Ylrght Report F. .LU ~ W O N I O I fctm rra. w m w&t. rect -)

Lawence E, Beterscn mane Gruber I--

- I*. T O T A L kb. O F C A 8 ¶ 9 W O . OF mcvn

I Qualified requesters m y obtain copice of t h i s repa-t fram DDC I

The 17.2 Bb. Rndro81~entsl Resoarch Satellite-18 (CRS-111-B) carried a se t of five raA.d aticm detectors designed i;d ~~ charged ps~ticY-es, X-rays, gamm~ rays, and codmlc mys in t h z ne- lPlrth aavircsopcat .! Qh mtell1t.e was Launched un April 28, 1367 into a highly cuptical orbi t whoee i n i t i a l apogee al t i txde rsas iii,200 kllcadttere and i n i t i a l -p?zQee a l t i tude was 8,- Ulmete ru . Detectors senait i-n t o trapped ~ t t i c l e include a golid a t a t e dctectm for electron fluxee above 0.4 Mev end protons 8-?1 MY, 12; =n=rG ~=k+,lE+,f= fsr tl;t';~~a g=,=ater t& frt=- +-<tan

g r e e t e ~ +?zah 1-8 hkv. A s e t of Gti.ger+tiielLea c w t e r a detected s o h r X-raya in the 1-14 A range, and electreas above 40 kev. G m m ~ m y counting mte s bttveen 30 key and 1.0 ~ e v , as mbl a@ the totdl csomip m y f lux, were gsovib 4 by the "ail-gamara" counter a huge #~I(TA) c q s + l surrounded by ar c$arged part icle shield conelating of plast ic scinti lhA&r ccnnectad in elcctrkcaP mticoheidence h ~ t b the central rc in t l l la tor . Signal8 h*)lll most channels were toxtvertet t o am.Icrg voltqgee by 1age.rieM.c count mte mte,-6. Gech c W e l uas saeprled & h u t m c e a minute t o mdvlatc a aubcarrder oasiflaa- tor in the t e l e t r y eyartem. Semdi lo# c o w i t b g w t e channel8 were converted 'to a quaei-digital f'o-t before saapli.ng. Data has been mcei**d n e u l y eontinuoutliy f m x launch uitil temir4atic-m api stme 3, 1966, rand b6, been ~ i t o r e a occesicmuly t o assera the perf'oreauce sf the fnstmrmbntatim.