pioneer 11 encounter

8/7/2019 Pioneer 11 Encounter

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I P N W I 7A I A I f I 1 i 2 " W : 1 1 1 1 N ' 1 E R

At 9.21 p.m. PST on Mcnday, December

2, 1974, Pioneer 11 will hurtle at the un-

precedented speed of 107.373 miles per

hour past Jupiter, only 26,600 miles

above the Jovian clout tops. This Arnen-can spacecraft is mans second trip to theSolar System s largest planet, but itpenetrates three times closer to Jupiterthan did Pioneer 10 which flew by Jupiter81,000 miles above the cloud tops almostone year beforehand.

The closer approach of Pioneef 11 is de-signed to probe deeper into the radiationbelts of energetic electrons and protons

that are trapped in Jupiter's magneticfield. Also the close approach permits theus e

,

piter's gravity and orbital motionto fli ioneer 11 across the Solar Sys-

ters to meet with the next outermostp;arlet, • ringed Saturn, in 1979. Pioneer

11 is thus man's first attempt to useenergy derived from a pass near JupiterWily to the next outer planet, an essen-

tial maneuver for ;ontinued economicexploration of the outer Solar System

Not only is the trajectory of Pioneer 11

passing much closer to Jupiter than Its

predecessor, but also it is directed qultcdifferently, so as to reduce the time that

the spacecraft must be in the radiationbelts. This is expected to safeguard the

electronics and scientific instruments of

Pioneer from damage from the energeticprotons and electrons Controllers have

directed the spacecraft Into the Joviansystem from far below Jupiter's south

pole Along this trajectory the spacecraft

will hurtt3 almost straight up through the

doughnut-shaped inner radiation belt,many thousands of miles per hour faster

than any man-made object has traveledbefore.

Passage through the belt at high sl -dand high angle should allow Pioneer 11

to emerge unscathc,d while at the same

time permitting the spacecraft to enterthe Darrow planetary flyby corridor that

will ensure a later encounter with theplanet Saturn.

Additionally, Pioneer 11 s trajectory dif-

feis from Its predecessor because the

passage is counter to the direction of

Jupiter's rotation (Figure 1). Thus, dur-

ing the encounter, the spacecraft willsample a complete revolution of the

planet's magnetic field ano Jupiter s radi-

ation belts, and will observe the planet's

surface features over several planetary

revolutions. Moreover, because the

spacecraft approaches Jupiter from the

south pole arid leaves over the north

pole. experimenters expect to obtain

their first look at Jupiter poles. impossi-

ble ♦ • om Earth and from Pioneer 10 In-

stead of the familiar banded Jupiter, the

polar views transmitted by Pioneer 11

should show a circular polar region bor-

dered with concentric rings. One theory

suggests that the p< f ar atmosphere istranspa7ent and will thereby permit

Pioneer s instruments to look deep down

Into the Jovian atmosphere

Since Its launching on April 5, 19

Pioneer 11 will have traveled 620 mi

miles when it reaches Jupiter But

destined for an even longer journey A

Jupiter passage it will travel high abthe plane of the ecliptic—the plane

Earths orbit around the Sun—and th

descend to Saturn s orbit where

scheduled to rendezvous with t

planet If Pioneer 11 does survive p

sage through Jupiter s radiation bel

will, In October 1979. provide mank

with a first close look at the unique rin

planet of the Solar System

During the several weeks around

date of closest approach to Jupite

termed periapsis—a team of spacec

controllers, analysts and scientistsNASA Ames Research Center (Fig

2;, and personnel of NASA's Deep Sp

Network, will run a three-shift, 2

hours-a-day control operation Apply

experience obtained during the flyb

Pioneer 10 last year, they will be aler

danger to they distant spacec raft fr

possible but unpredictable problems a

ing in the environment of the Jovian s

tem

Most of the commands sent from

ground to the spacecraft during the

counter period. amounting to mathousands of instructions. will be direc

to the imaging photopolarimeter wh

scans across Jupiter and some olarge satellites to gather information

will later be assembled by compute

form spin-scan images of these bod

(Figure 3). To send pictures of Jup

and its satellites to Earth. the imag

photopolan meter scans a light-sensi

device across the disc of t-ie plane

the rotation of the spacecraft The

strument measures brightness of light that is gathered from each of m

small areas of the scene The brightnreading is converted into a bin

number—somewhat like the dots a

dashes of Morse code—and sent

radio from the spacecraft to Earth H

the stream of impulses is converted b

to appropriately positioned small g

areas on film, thus creating a facsimil

the view of Jupiter seen from the spa

craft. As the data needed to make o

spin-scan Image of the planet has to

gathered over a period o f tIso

times taking as long as one r. a

because the spacecraft is moving a

Jupiter is rotating on its axis. the pictu

•`PIONEER 10

uulsru+4^•• TRAJECTORY

t ,•♦ p+OA""DE'•^•♦• •EURO PA • •

♦b•.s♦.0 ♦♦♦•

row.^♦ ♦♦1..•+•AI TIME

PIONEER 11•.•♦ ^^

TRAJECTORY•++ +

NON EN PULAN V01* 00 X VIAN SYS11

FIGURE 1 The Pioneer 10 and Pioneer 11 flybys of Jupiter. The positions of the Galilean satellites.

Callisto, Ganymede. Europa and to and cf the Innermost satellite Amafthea. are shown at the time of

periapsis of Pioneer 11 The dots on the orbits show the movement of the satellites and bc. - h Pioneer

spacecraft over intervals of two hours.



Later the distortions are removed by

! ,!► !her computer processing of the re

turned data, but this enhancement of thi

returned Images takes time

Informatien from Vie spacecraft arrives

back at Earth on three large antennas.

2 4.0-foot diameter dishes as large as

for 'ball fields One is in the Mohave D es

Spain, and the third Is In Austral , a Thus

as the Earth turns on Its axis and the

spacecraft sets at one of these stattoos.

the spacecraft rises at the next station.

Signals can accordingly be received un-

interruptedly for 24 hours each day

Figure 2. The uista , it spacecraft i' ;ontrolled from NASA Arses Research C ( -nter near San f Wnc

California. where teams of High, controllers scientists. and engineers maintain 24hours wduring the period ref encour " !Photo of personnel at consoles of the PM OC)

Figure 3 A typ ical sp in-scan Image of Jupiter returned from Pioneer I0 when i t f lew pest Jupi tDecember 1973- Pioneer 11 will return s imi lar pic tures but a t di f ferent look angles (Ph oto of Juby Pioneer 10).

D ATETT I M E —EV E N T

N O V . 3011:28m. ULTRAV IOLET MEASUREMENT OF C ALLISTO

DE C. 1 11:26 a.m. ULTRAVIOLET ME ASUREMEN T OF GANY MED E10:18 a.m. INFRARED MEASUREMENT OF CALLISTO

12:21 a.m.1:50 a.m.

1:56 p m.

2:09 p m.2: e 5 p m.

5:00 p.m.

5:13 p.m.

7:02 p.m.

7:09 p.m.

8:15 p m.

10:30 p.m.

10:52 p.m.

1 1 :.0 0 - P.M.

7:58 a.m.

11:43 mm.

CLOSEST APPROACH TO CALLISTO. 488.730 MILES

ULTRAVIOLET MEASUREMENT OF GANYMEDE

INFRARED MEASUREMENT OF GANYMEDE

CLOSEST APPROACH TO GANYMEDE, 43`:.195 M ILESULTRAVIOLET MEASUREMENT OF EUROPA

START INFRARED MEASUREMENTS OF JUPITER

INFRARED MEASUREMENT OF AMALTHEAINFRARED MEASUREMENT OF 10

CLOSEST APPROACH TO 10. 195.120 MILES

CLOSEST APPROACH TO EUROPA, 364.575 MILES

CLOSEST APPROACH TO AMALTHEA. 79.229 M I L E S

INFRARED MEASUREMENTS OF AMALTHEA

INFRARED ME ASUREMENTS OF JUPITER

INFRARED MEASUREMENT OF 10

INFRARED MEASUREMEN T OF GANYMED E

9:45 p.m.I INFRARED M EASUREMENT OF CALLISTO

TABLE 1. Some Experiments

SCIENCE EXP ERIMENTS

The science experiments to be made byPioneer 11 in the Jovian system are

much the same as those made by

Pioneer 10 (l able 1).

• Measure Jupiter s magnetic field and

magnetosphere w!th two instruments

called magnetometers.

•Sense the interacho-s of Jupiter with

the solar wind—the stream of charged

particles flowing outward from the Sun

across the Solar System—by use of

an instrument that detects energetic

electrons and protons.

• Me asure the intensities, energies, and

distribution of energetic electrons andprotons in the radiation belts of Jupiter

by use of four particle detecting exper-

iments.

• Check on meteoroids and dust near

Jupiter by means of a special four

telescope systems and a group ofpanels that detect punctures from im-

pacting meteorites.

• Sense Jupiter atmospheric composi-

tion and provide a thermal map of

Jupiter's heat emission by use of in-

struments that measure ultraviolet

and infrared radiation beyond thevisible spectrum

• Obtain spir,-scan Images of Jupiterand Its clouds and of several of itslarge satellites. using the Imaging

photopolarimeter.

• Measure the atmospheric characteris-

tics of the Jovian atmosphere by ob-

serving the changes to the radio

waves from the spacecraft as it passes

into and emerges from occultation by

Jupiter

• Improve measurements of the orbit of

Jupiter and its satellites and the mass-

es of these bodies by precise tracking

of the motion of the spacecraft as it

passes through the Jovian system.



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N

N

6:00 P.M. P.S.T. December 2

7:00 P M. P.S.T. December 2

N

hN

I r Z A3:00 P .M . P .S .T .

D e c e m b e r 210:00 A .M . P .S .T .

D e c e m b e r 2

Figure 0 This series of drawings produced wiginaappear Nom the Pioneer 11 spacecraft Bunny the e

details of the planets north and south polar region

pleteF a c i rcui t of the p lanet by c ross-c rafts own incom ing tra ;ec-

ter i ts see n f rom the space -

l osest approac of the- -— Is near the left hand edge of the

tor wi ll be near the upper r ight-handof the disc of the planet. M ost of the

I e .

On ihis encounter there is noop i^ortunity for the spacecraft to

occult any of the Jovian satellites. so

INAAUON,

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Figure 5. a) is a diagram of the pants of Pioneer

10 and Pioneer 11 from Earth . Jupiter andbeyond. Pioneer 10 shoots beyo; d Jupiter rsyht

out of the Solar System. P:o eer 11 zoomsaround Jupiter which flings It right ac, oss the, Oar System to intercept Sa;ur t rn tho oppo-site side Of the Sun in 1979 ' it of" on theorbits are positions at one month Inf*_•rvals

their atmospheres cannot be probed di-

re c t ly as was the atm osphere of to whenPioneer 10 went behind that satellite

T he flyby trajectory is Incl ined at an angleof about 50 degre es to Jupiter s e quator .As a result, the Pioneer 11 post flybyt ra jec tory appears to proce ed st ra ight upout of the ecliptic relative to Jupiter Ac!wally the spacecratt almost paces Jupi-ter around the planets solar orbit, but

rises high above Jupiter until. in 1977, It

begins to fall back toward the ecliptic

plane for its rendezvous with Saturn

( Figures 5a and 5b).

b) Theo a same trajectories are shown here in almo

rises high abois Jupiter before descending on theorbit



N

Midnight P.S.T. December 2

N

i

N

t

4:00

D

10.00 P M. P.S T December 2

9:00 P.M. P.S.T. De cem ber 2

As with Pioneer 10 there are five stages

of the encounter (Table 2). The first oc-

cupies about three weeks after

November 2, when the spacecraft pass-

es from interplanetary space Into the

outer regions of the Jovian system, mov-

ing from about 15 million to 6 millionmiles from the planet.

Stage Two covers entry into the Inner

system Sometime after 8:00 a m. on

November 25 Pioneer 11 Is expected to

,, )ass through the bow shock wave in the

solar wind created by Jupiter s magnetic

field. A short while later, the spacecraft

will enter the magnetosphere where the

magnetic fteld of Jupiter prevents the

solar wind from approaching closer to the

planets surface

Stage Three is that period wh

11 continue, flying through

magnetosphere from about 3

miles from the planet

nally on a computer shows how the planet Jupiter will

r..wcro..

ATETIMEDISTANCE FROM JUPITER,STAGP.S.TkilometersENCOU

NOV. 24:00 p.m.27,398,000J1124:00 p.m.19,162,000

224:00 p.m.10,646,00074:00 p.m.6.111,0002304:00 p.m._3.103,000

DEC. 14:00 p.m.1,956,000329:21 p.m.114,0_00'434:00 p.m.1,382.000

44:00 p.m.2,f? j7.O00

84:00 p.m.6.631.000

1 34:00 p.m.11.127.0005234:00 p.m.19.615.000

314:00 p.m.26,207,000

Note: Dist ...es are from center of Jupiter. Closest approach Is to 42,820 kilom

above the cloud tops.

I opposite side of the Sun to meet with Saturn on Its



S A T E L L I T E D A T E T I M E P S T

H A D E S N O V .7 4 : 3 0 a .m .P O S E I D O N 7 4 : 4 9 p .m .P A N 8 7 : 5 0 p . m .A N D R A S T E A 1 0 7 : 2 9 p . m .H E R A 2 1 1 0 : 0 3 a . m .D E M E T E R 2 1 1 0 : 5 0 a . m .H E S T : A 2 1 5 :21 p.m.

C A L L I S T O D E C .15 : 2 7 p . m . 1 . 1 2 5 . 2 9 5G A N Y M E D E 28 0 1 a . m .

I6 2 4 . 9 5 3

E U R O P A 22 : 0 6 p .m . 3 7 2 . 8 0 3t0 25 : 2 3 p .m . 2 1 7 , 9 4 5; A M A L T H E A 28 1 0 p .m . 6 8 . 6 3 0

Times of Crossing Satel l ite Orbhs

(1,812.800)

( 1 , 0 0 1 . 14 0 1

(601.780)

(352.560)

(137.260)

DI STANCE FROM JUPI TER

milesIkm

14,683.0001 4 . 4 1 7 . 0 0 0

1 3 . 8 4 1 . 0 0 0

1 2 . 8 2 0 . 0 0 0

7. 24 8 . 0 0 0

7 . 2 3 1 . 0 0 0

7 . 0 8 4,0 0 0

( 23. 632 . 0 0 0 )( 23. 20 4 . 0 0 0 )( 2 2 . 2 7 6 . 0 0 0 )

(20,634.000)

( 11 , 6 6 7. 0 0 0 )

( 1 ? 6 3 9 .0 0 0 )

(11.403.000)

November ?5 About '3 00 p m onNovember 26 the spacecraft shouldenter the magnetosphere Imaging (pic-

ture taking) and photometry (lightanalysis) of Jupiter starts on November 2over a period of 4 to 8 hours each day

through November 24, and then con-tinues for 23 hours each day until 3 00p m on December 9 By 9 2 p m onNovember 30 all pictures of Jupitershould become better in quality tna;those obtained by telescope from Earth

During the close encounter periodPioneer 11 should also return 3 picturesof Callisto and one each of Ganymedeand to T his will be the second time thatGanymede has been photographed butthe first time for Callisto and lo.

ering the day and a halt

ea-ents and fl ies by the large Inner

ites Pioneer 11 makes hundreds of

r ing Stage Five, Pioneer 1 1 leaves

on m i les f rom Ju pi ter ; then the orbi ts

as th e

Pioneer 11 passes at 364,575

r 11t he orbi t of Am al thea. the inner-

p iter s satellites and ap-aches to within 79.224 miles of that

Pioneer11also :aspects Callisto.Ganymede, and Europa In ultraviolelight and makes infrared measurementsof Callisto, Ganymede. Amalthea and Ir(Table 4) Some measurements are re-peated on the outbound p assage

Just before closest approach at 9.21 p mon Decem ber 2 Pioneer 11 enters thecold blackness of Jupiter s shadow. and40 seconds afterwards Is hidden fromEarth by the bu lk of the planet A radioblackout occurs as the spacecraft hurtlesthrough the most intense region of theradiation belts

Mission controllers arid scientists will notknow A Pioneer 11 has survived the radi-ation until 9.43 p m (21 minutes and 44

seconds after periapsis). when the

spacecraft emerges from behind Jupiterand radio contac t car again take p lace. IP ioneer 11 does surv ive, informat ion w i lagain pour back over the radio link toEarth, and P ioneer w i l l cont inue i ts sp in-

scan picture taking and other scientificobservations as Itspeeds from the Jo-v ian system

JUPITER PICTURESPicture taking sequences of Pioneer 11

are summarized in Table 5 Color pic-tures will start to be Interesting around

Nov ember 2 w hen the planet, a l it t le over1 7 m i ll ion m i les f rom the spa cecraf t , w i l lfill 1 ! 50th of the imaging photopolarime-ter s 14 degree field of view. ByNovember 27 Jupiter roll occupy 1 ,10thof thrn view and byrvemhnr ?O 1 7 t h

_D A T

ET I M E _E V E N T

NOV. 25 8:00 a.m.E N T E R J U P IT E R S B O W S H O C K W A V E( E A R L I E S T )

26 8 :00 a.mE N T E R J U P IT E R ' S M A G N E T O S P H E R E( E A R L I E S T )

D E C . 2 3 : 2 1 p . m .E N T E R R A D I A T IO N B E L T A T 3 . 5 J U P I T E RD I A M E T E R S F R O M C L O U D S A N D 6H O U R S F R O M r , L U S E S I A P P R O A C H

9 : 0 0 p . mG O I N T O S H A I ., O W O F J U P I T E R• 21 SECONDS FOR 33 MINUTES AND 31 SECONDS

O F S O L A R O C C U L T A T IO N

9 : 00 P . M .G O B E H I N D J U P I T E R F O R 4 242 SECONDS MINUTES AND 2 SECONDS OF RADIO

O C C U I T A T I O N ( B L A C K O U T ) .

9 : 2 1 p . mC L O ! : E 3 T A P P R O A C H ( P F R I A P S IS )9 : 4 3 r . .m .O U T O t O C C U L T A T IO N . R A D I O S I L E N C E

S H G ' , L D E N D

3 3 : 2 1 a .m .L E A V E R A D I A T I O N B E L T

10 l MIDI GH TL E A V E B O W S H O C K ( L A T E S T )



The planet s disc will exceed the field of

view of the Imaging Instrument al 12hours before periapsis so that only part

of Jupiter will subsequently be Imaged

until the spacecraft moves away from the

planet again

Since most of the Pioneer 11 pictures will

be views down toward either the north or

south pole, the general appearance ofJupiter will be dramatically different from

the Pioneer 10 or Earth view—the new

pictures will show concentric circulartortes around each pole instaad of thefamiliar parallel bands seen in telescopes

from Earth

Details shown In every picture in the 96-

hour period centered on periapsis should

be better than the best views fromEarth-based telescopes Pioneer will betaking It,, best pictures in the 24 hours

before and after periapsis when withinabout one million miles of Jupiter Sev-

eral close-up pictures of Jupiters cloud

tops taken near periapsis will be some-

,r,hat distorted at first viewing but they ,,ill

be improved oy subscquent computerprocessing fhe picture lust before

periapsis, which will show a part of thesurface of the planet including the Great

Red Spot, will be about five times better

In detail than the best pictures f.omEarth However, during closest approach

t he Intense particle radiation in the belt

may cause the photopolarimeter tocease to operate temporarily, or may re-

duce the quality of the Images

During the 96 hours centered on periap-

sis the spin-scan imaging system willsend to Earth about 40 pictures of the full

planet, many pictures of pof lions of the

surface three of the satellite Callisto.and one each of Ganymede and to As

Pioneer 11 swings around Jupiter. Sunangles not possible from Earth (and not

obtained from Pioneer 10) will be seen

with almost every picture

Incoming Colo- and black and white pic-

tures will be displayed on TV monitors as

they arrive frrim PIoi'eer They will then

be photographed from 'he mon;tors and

distributed to the news media

O N T O S A T U R N

When Pioneer 11heads out from the Jo-

vian system its mission Isby no meanscomplete It wiil become the first space-

craft from Earth to fly by the mightyplanet Saturn. only slightly smaller than

Jupiter but with a unique ring system.(Figure 6).

In 1979 the spin-scan imaging systwill provide mankind with the first clo

up views of satellites of Saturn. the se

eral distinc t rings, and the cloud bands

the planet itself And the scientific exp

iments with Pioneer 11 will sense thefects of Saturn on the solar wind, me

ure the heat radiated from the planet, a

search for a magnetic field After its ecounter with Saturn Pioneer t 1 will h

out into interstellar space, mankinsecond emissary to the stars

S T U D Y P R O J E C T S

O N E

lake the various events listed in Table

through 5 and make a combined listing

the sequential happenings when Pion

11 flies through the Jovian system Lthe date, time, what happens and lea

a column for remarks about each hapening Give distances In both kilometand miles It will be necessary for you

use simple multiplication. a slide rule

a desk calculator to make the conv

sions between the English and the Me

systems

TWO

Use the list you have made: during encounter watch TV. listen to radio, a

read newspapers to check each even

It is reported Fill in remarks as to whadiscoverod

T E S T I M A G E S O F J U P I T E R W I L L B E O B T A I N E D B E F O R E A N D A F T E R T H E

PERIOD DETAILED ABOV E. ENCOUNTER END S AT 4:00 P .M. 3 JANUARY 1975

A P P R O X IM A T E N U M B E R O F

P ICTURES

25

17

2215

24

DEC 1I142

2811

1 11

15

18

10

22

28

19

TABLE 5. Images of Jovian Objects

THREE

As a classroom project place a geome

cal drawing on the blackboard a lar

square or a triangle Each student mak

a '4 Inch hole in the center of a caHolding the card at arms length in fro

of the eye it is impossible to sr l e all

geometrical design or he board, onpart of It However L)y scanning the h

across the blackboard in a seriessweeps. the student can see the whole

the figure on the blackboard but not alone time This Illustrates the spin-sctechnique used to build up a pictureJupiter ove r a period of time by scann

the disc with a `;mall aperture telescop

R E A D I N G L I S T

Watch TV newscasts and special pgrams

Listen to radio newscasts

Read yourKcal newspaper or natio

newsmagazine during the encounperiod.

O B J E C T

JUPITER

JUPITER

JUPITER

JUPITER

JUPITER

J U P ITER

JUPITER

CALLISTO

JUPITER

CALLISTO

GANYMEDE

JUPITER

IO

JUPITER

JUPITER

JUPITER

JUPITER

JUPITER

JUPITER

DATE

NOV 25

26

27

28

29

30

pioneer 11 encounter

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