seminar report part 2

8/9/2019 Seminar Report Part 2

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Seminar 2014Solar Sail

1. INTRODUCTION TO SOLAR SAILING

1.1 HISTORICAL PERSPECTIVE TO DATE

The concept of solar sals s not at all no!el. "ohannes #epler $as the frst person to co%e

&p $th ths I'ea. "ohannes #epler o(ser!e' that co%et tals pont a$a) fro% the S&n an'

s&**este' that the s&n ca&se' the effect. In a letter to Galleo n 1+1,- he $rote- Pro!'e shps or

sals a'apte' to the hea!enl) (ree/es- an' there $ll (e so%e $ho $ll (ra!e e!en that !o'. He

%*ht ha!e ha' the co%et tal pheno%enon n %n' $hen he $rote those $or's- altho&*h hs

p&(lcatons on co%et tals ca%e se!eral )ears later.

"a%es Cler0 a2$ell- n 13+14+5- p&(lshe' hs theor) of electro%a*netc fel's an' ra'aton-

$hch sho$s that l*ht has %o%ent&% an' th&s can e2ert press&re on o(6ects. a2$ell7s

e8&atons pro!'e the theoretcal fo&n'aton for saln* $th l*ht press&re. So () 13+5- the

ph)scs co%%&nt) an' (e)on' 0ne$ s&nl*ht carre' %o%ent&% that $o&l' e2ert a press&re on

o(6ects.

"&les Verne- n 9ro% the Earth to the oon- p&(lshe' n 13+:- $rote there $ll so%e'a)

appear !eloctes far *reater than these of the planets an' the pro6ectle - of $hch l*ht or

electrct) $ll pro(a(l) (e the %echancal a*ent ...$e shall one 'a) tra!el to the %oon- the

planets- an' the stars. Ths s poss(l) the frst p&(lshe' reco*nton that l*ht co&l' %o!e shps

thro&*h space. G!en the 'ate of hs p&(lcaton an' the $'esprea'- per%anent 'str(&ton of

hs $or0- t appears that he sho&l' (e re*ar'e' as the or*nator of the concept of space saln*

() l*ht press&re- altho&*h he '' not 'e!elop the concept f&rther. Verne pro(a(l) *ot the 'ea

'rectl) an' %%e'atel) fro% a2$ell7s 13+5 theor) ;altho&*h t cannot (e r&le' o&t that

a2$ell or an nter%e'ar) reco*n/e' the saln* potental an' (eca%e the so&rce for Verne Ernest Nchols an' Gor'on H&ll con'&cte' a s%lar n'epen'ent

e2per%ent n 1=,1 &sn* a Nchols ra'o%eter.

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Al(ert Ensten pro!'e' a 'fferent for%als% () hs reco*n/n* the e8&!alence of

%ass an' ener*). He s%pl) $rote p ? E@c as the relatonshp (et$een the %o%ent&%- the

ener*)- an' the spee' of l*ht.

S!ante Arrhen&s pre'cte' n 1=,3 the poss(lt) of solar ra'aton press&re 'str(&tn*

lfe spores across nterstellar 'stances- the concept of pansper%a. He apparentl) $as the frst

scentst to state that l*ht co&l' %o!e o(6ects (et$een stars.

9re'rch an'er ;Tsan'er< p&(lshe' a techncal paper that ncl&'e' techncal anal)ss of

solar saln*. an'er $rote of &sn* tre%en'o&s %rrors of !er) thn sheets an' &sn* the

press&re of s&nl*ht to attan cos%c !eloctes.

".D. Bernal $rote n 1==- A for% of space saln* %*ht (e 'e!elope' $hch &se' the

rep&ls!e effect of the s&n7s ra)s nstea' of $n'. A space !essel sprea'n* ts lar*e- %etallc

$n*s- acres n e2tent- to the f&ll- %*ht (e (lo$n to the l%t of Nept&ne7s or(t. Then- to

ncrease ts spee'- t $o&l' tac0- closeha&le'- 'o$n the *ra!tatonal fel'- sprea'n* f&ll sal

a*an as t r&she' past the s&n.

The frst for%al technolo*) an' 'es*n effort for a solar sal (e*an n 1=+ at "et

Prop&lson La(orator) for a propose' %sson to ren'e/!o&s $th Halle)7s Co%et.

Aro&n' ths pero' a n&%(er of scence fcton a&thors $rote of spaceshps propelle' ()

%rrors- %ost nota(l) the 9rench a&thors 9a&re an' Graff*n) n 133=- ho$e!er t $as not the

&ntl earl) ,th cent&r) that the 'ea of a practcal solar sal $as artc&late'. In the earl) 1=,s

the So!et father of astrona&tcs #onstantn Tsol0o!s0) an' hs collea*&e 9r'rc0h Tsan'er

(oth $rote of F&sn* tre%en'o&s %rrors of !er) thn sheets an' F&sn* the press&re of s&nl*ht

to attan cos%c !eloctes. There s so%e &ncertant) re*ar'n* 'ates (&t t appears that

Tsan'er $as the frst to $rte of practcal solar saln* so%et%e late n the s&%%er of 1=5. Hs

'eas see% to ha!e (een nspre' n part () Tsol0o!s0)7s %ore *eneral $rtn*s on prop&lson&sn* l*ht fro% 1=1.

9ollo$n* the ntal $or0 () Tsol0o!s0) an' Tsan'er the concept of solar saln*

appears to ha!e re%ane' &n0no$n for o!er thrt) )ears- &ntl n the 1=:,s $hen the concept $as

ren!ente' an' p&(lshe' once a*an n the pop&lar lterat&re. The frst A%ercan a&thor to



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propose solar saln* appears to ha!e (een the aerona&tcal en*neer Carl le)- $rtn* &n'er

the pse&'on)% R&ssell San'ers to protect hs professonal cre'(lt). In a) 1=:1- n

Asto&n'n* Scence 9cton- le) 'sc&sse' the 'es*n of a feas(le solar sal an' strate*es for

or(t rasn* n so%e techncal 'etal. In partc&lar he note' that solar sals co&l' (e 7tac0e'7

allo$n* a spral n$ar's to$ar's the S&n. E!en n 1=:1 le) $as opt%stc a(o&t the (enefts

of solar saln* for nterplanetar) tra!el an' sa$ t as &lt%atel) %ore practcal than roc0et

prop&lson. A s%larl) opt%stc !e$ $as ta0en so%et%e later n 1=:3 thro&*h a separate

proposal an' e!al&aton () Rchar' Gar$n- then at the IB atson la(orator) of Col&%(a

Un!erst). Gar$n a&thore' the frst solar sal paper n a $estern techncal p&(lcaton- the

6o&rnal "et Prop&lson- an' cone' the ter% Fsolar saln*. le) reco*nse' that solar sals

re8&re no propellant an' are contn&o&sl) accelerate'> therefore allo$n* lar*e !eloct) chan*es

o!er an e2ten'e' pero' of t%e. S&ch $as Gar$n7s enth&sas% an' opt%s% for solar saln*

he concl&'e' that Fthere are cons'era(le 'ffc&ltes connecte' $th space tra!el- (&t those

connecte' $th the sal appear relat!el) s%all.

9ollo$n* the 'sc&sson of solar saln* () Gar$n- %ore 'etale' st&'es of the or(ts of

solar sals $ere &n'erta0en '&rn* the late 1=:,s an' earl) 1=+,s. Se!eral a&thors $ere a(le to

sho$ that- for a f2e' sal orentaton- solar sal or(ts are of the for% of lo*arth%c sprals.

S%ple co%parsons of solar saln* $th che%cal an' on prop&lson s)ste%s sho$e' that solar

sals co&l' %atch or o&t perfor% these s)ste%s for a ran*e of %sson applcatons. S&ch earl)

st&'es e2plore' the f&n'a%ental pro(le%s an' (enefts of solar saln*- (&t lac0e' a specfc

%sson to 'r!e 'etale' anal)ses an' to act as a foc&s for f&t&re &tlsaton.

B) 1= NASA $as f&n'n* lo$le!el st&'es of solar saln* at the Battelle la(oratores

n Oho- $hch *a!e post!e reco%%en'atons for f&rther n!est*aton. D&rn* the contn&aton

of ths $or0 "ero%e r*ht- $ho $o&l' later %o!e to "PL- 'sco!ere' a tra6ector) that co&l'

allo$ a solar sal to ren'e/!o&s $th co%et Halle) at ts perhelon n the %'1=3,s. The fl*ht

t%e of fo&r )ears $o&l' allo$ for a late 1=31 or earl) 1=3 la&nch. Untl then a 'ffc&lt

ren'e/!o&s %sson $as tho&*ht to (e near %poss(le n s&ch a short t%e &sn* the technolo*)

of the 'a). A se!en to e*ht )ear %sson ha' (een en!sa*e' &sn* solarelectrc on prop&lson-

re8&rn* a la&nch as earl) as 1=. The scence co%%&nt) sa$ a ren'e/!o&s as essental for a

h*h 8&alt) %sson. These post!e res&lts pro%pte' then NASA "et Prop&lson La(orator)

'rector Br&ce &rra) to ntate an en*neern* assess%ent st&') of the potental rea'ness of



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solar saln*. Ne$l) apponte' fro% a fac&lt) poston at the Calforna Instt&te of Technolo*)-

&rra) a'opte' solar saln* as one hs (ol' 7p&rple p*eon7 pro6ects- as oppose' to the %ore

t%' 7 grey mice7 %ssons he (ele!e' "PL ha' (een proposn* for f&t&re %ssons. 9ollo$n*

ths nternal assess%ent- a for%al proposal $as p&t to NASA %ana*e%ent n Septe%(er 1=+.

The 'es*n of a co%et Halle) ren'e/!o&s %sson &sn* solar saln* $as ntate' n No!e%(er

of the sa%e )ear. As a res&lt of the nterest n solar saln*- proponents of solarelectrc

prop&lson ree!al&ate' ther perfor%ance est%ates an' n the en' $ere co%petn* 'rectl) $th

solar saln* for f&n'n*. The solar electrc prop&lson s)ste% ha' a lar*er a'!ocac) *ro&p (oth

$thn NASA an' n n'&str). As a res&lt of an e!al&aton of these t$o a'!ance' prop&lson

concepts NASA selecte' the solar electrc s)ste% n Septe%(er 1=- &pon ts %erts of (en* a

less- (&t stll cons'era(le rs0 for a co%et Halle) ren'e/!o&s. A short t%e later a ren'e/!o&s

%sson &sn* solar electrc prop&lson $as also 'roppe' '&e to escalatn* cost est%ates. The

enth&sas% of the scence co%%&nt) for a ren'e/!o&s %sson ha' n fact lea' to the lo$er cost

fl)past opton (en* 'sco&nte'. Therefore- $hen the a'!ance' prop&lson re8&re' to ena(le a

ren'e/!o&s %sson $as 'elete'- so%e caref&l (ac0 steppn* $as re8&re' to 6&stf) a lo$er cost-

(&t less capa(le- fl)past %sson. Ult%atel) tho&*h- t $as too late an' Co%et Halle) $as

ntercepte' () an ar%a'a of So!et- "apanese an' E&ropean spacecraft- (&t no A%ercan craft.

A tr&e solar sal has )et to fl)- ho$e!er s*nfcant steps ha!e (een ta0en snce the

(e*nnn* of the 1==,Js. In 9e(r&ar) 1==- &n'er the *&'ance of Vla'%r S)ro%atn0o!- the

R&ssan Space Re*atta Consort&% 'eplo)e' a ,% spnnn* reflector- na%)a- for% a Pro*ress

s&ppl) !ehcle. O(ser!e' fro% the r staton ths 'eplo)%ent sho$e' that spn 'eplo)%ent

co&l' (e controlle' () pass!e %eans. In a) 1==+ a lar*e 'eplo)a(le reflector $as

'e%onstrate' '&rn* the Sh&ttle %sson STS. The 15% Inflata(le Antenna E2per%ent $as

pr%arl) 'es*ne' as a ra'o fre8&enc) reflector- (&t the pro%se of nflata(le technolo*)

to$ar's solar saln* $as clearl) 'e%onstrate' 'espte %sson ano%ales. In #Kln n Dece%(er

1=== the Ger%an space a*enc)- DLR- n assocaton $th ESA 'eplo)e' a s8&are- ,% solar

sal. Ths 'eplo)%ent no$ for%s the (ass for a f&t&re DLR@ESA nor(t 'eplo)%ent

'e%onstraton perhaps n earl) ,,+. 9&rther%ore- n A&*&st ,,5 the Instt&te of Space an'

Astrona&tcal Scence n "apan- ISAS- 'eplo)e' t$o solar sals n space fro% a S1, so&n'n*

roc0et. NASA an' se!eral pr!ate enterprses all see0n* to a'!ance solar saln* are also



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con'&ctn* f&rther $or0. It s th&s clear that the technolo*) s c&rrentl) &n'er*on* a re!!al n

nterest an' a rene$e' 'r!e to$ar's fl*ht stat&s.

1. SOLAR SAIL CON9IGURATIONS

The essental re8&re%ent of an) solar sal 'es*n s to pro!'e a lar*e- reflect!e

s&rface $th %n%al str&ct&ral s&pport %ass. 9&rther%ore- ths s&rface sho&l' (e easl)

'eplo)a(le an' %an&fact&re'.

1.2.1 Square Sail

The frst sal 'es*n concept cons'ere' s the s8&are sal- the opt%&% 'es*n of

$hch has fo&r 'eplo)a(le spars cantle!ere' fro% a central loa'(earn* h&(- as sho$n n

9*&re 1.1. Attt&'e control of the s8&are solar sal can (e ache!e' () n'&cn* tor8&es

*enerate' () artc&late' reflectn* !anes attache' to the spar tps- or thro&*h relat!e translaton

of the centreof%ass an' centreofpress&re of the sal.

1.2.2 Helio-Gyro

An alternat!e concept to the (oo% s&pporte' fl% s to &se spnn'&ce' tenson- as

n the helo*)ro or spnnn* 'sc sal. At frst the helo*)ro appears a %ore attract!e 'es*n as

the %echancal cantle!er spars are re%o!e'- ho$e!er the (la'es %a) re8&re e'*e stffeners to

trans%t ra'al loa's an' pro!'e torsonal stffness to allo$ (la'e rotaton for attt&'e control.

The pr%ar) a'!anta*e of the helo*)ro s the ease of pac0n* an' 'eplo)%ent.

1.2.3 Disk Solar Sail

The thr' concept s the 'sc solar sal- n $hch a fl% s hel' n tenson thro&*h spn-

the fl% %a) (e one contn&o&s sheet or se!eral se*%ents- $hch to*ether *enerate a near

contn&o&s fl%- as n 9*&re (elo$. The 'sc sal offers the sa%e (enefts of the helo*)ro (&t

$tho&t the h*h aspect rato (la'es.



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Figure 1.1 Solar sal 'es*n concepts ;I%a*e () NASA<

1. SAIL CHARACTERISTIC ACCELERATION

To ena(le sal 'es*n- conf*&raton an'@or re8&re%ents to (e co%pare' a stan'ar'

perfor%ance %etrc s re8&re'. The %ost co%%on %etrc for astro')na%cs s the sal

characterstc acceleraton- 'efne' as the solar ra'aton press&re acceleraton e2perence' () a

sal facn* the S&n at the 'stance of one Astrono%cal Unt ;AU


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ener*) of $hch l*ht s co%pose'. As a photon hts the s&rface of the sal t %parts a

%o%ent&% onto the sal fl%- th&s appl)n* an %p&lse to the entre solar sal. Then- $hen the

photon s reflecte' a reacton %p&lse $ll also (e e2erte' on the solar sal. The co%(naton of

these t$o %p&lses s&%%e' across the entre fl&2 of photons nc'ent on the sal fl% then lea's

to a force 'recte' nor%al to the s&rface of the sal- as sho$n n Figure 1.2.

Incident

Radiation, ui

Reflected

Radiation, ur

Reflective

Sail Film,

Of area A

Thrust, n

L

Figure 1.2 Inc'ent an' reflecte' forces on 'eal solar sal

The orentatons of the solar sal- an' so the force !ector- s 'escr(e' relat!e to the S&nlne ()

the sal ptch an*le- α- an' cloc0 an*le- δ. The orentaton of the sal ptch an' cloc0 an*les- the

sal control an*les- s 'efne' n Figure 1.3. e note that the sal control an*les can (e 'efne'

as ether>

,o M α =, o ,o M δ +, o

or- =,o M α =, o ,o M δ 13, o

ho$e!er- each s e8&all) correct an' e8&all) $'el) &se' $thn lterat&re.

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Sun-line

Sail Normal

Normal to Sun-

line, within orbitplane

Unit vectornormal to orbit

plane

α

δ

Figure 1.3 Orentaton of the sal ptch an' cloc0 an*les

B) altern* the orentaton of the solar sal relat!e to the nco%n* photons- the solar ra'aton

press&re force !ector can n prncple (e 'recte' to an) orentaton $thn =,o of the S&nlne.

As the ptch an*le ncreases ho$e!er- the %a*nt&'e of the solar ra'aton press&re force

'ecreases '&e to the re'&cton n pro6ecte' sal area an' the re'&cton n the co%ponent of the

solar ra'aton press&re force 'recte' nor%al to the sal s&rface.

Solar sals are contn&o&sl) accelerate' so that ther or(ts are 8&te 'fferent fro% the

&s&al (allstc arcs follo$e' () con!entonal spacecraft. B) choosn* ether a ne*at!e or post!e sal ptch an*le- $th respect to the S&nlne- the solar sal $ll ether spral n$ar's

to$ar's the S&n- or o&t$ar's a$a) fro% the S&n. S&ch 7tac0n*7 pro!'es solar sals $th the

a(lt) to ena(le a $'e ran*e of %sson applcatons. The rate at $hch the solar sal $ll spral

s of co&rse a f&ncton of ts characterstc acceleraton. B) an approprate se8&ence of sal

orentatons- essentall) an) pont n the solar s)ste% can (e reache'. Ho$e!er- for %ssons to

ren'e/!o&s $th planets- co%ets or astero's- the sal orentaton %&st (e contn&o&sl) altere'

alon* ts tra6ector) to ens&re that the solar sal %atches the !eloct) of the tar*et (o') $hen t s

ntercepte'. Opt%saton %etho's can (e &se' n s&ch nstances to 'eter%ne the (est sal

orentaton t%e hstor) to %n%se the transfer t%e to the tar*et (o').

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. SOLAR RADIATION PRESSURE

.1 9ORCE ACTING ON A SAIL

Solar ra'aton e2erts a press&re on the sal '&e to reflecton an' a s%all fracton that s

a(sor(e'. The a(sor(e' ener*) heats the sal- $hch rera'ates that ener*) fro% the front an'

rear s&rfaces.The %o%ent&% of a photon or an entre fl&2 s *!en () p ? E@c- $here E s the

photon or fl&2 ener*)- p s the %o%ent&%- an' c s the spee' of l*ht. Solar ra'aton press&re s

calc&late' on an rra'ance !al&e of 1+1 @% at 1 AU ;earths&n 'stance


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here R s 'stance fro% the s&n n AU. An act&al s8&are sal can (e %o'ele' as

9 ? 9, ;,.5= ,.++ cos ,.,11 cos 5< @ R

Note that the force an' acceleraton approach /ero *enerall) aro&n' ? +, rather than =, as

one %*ht e2pect $th an 'eal sal.

Solar $n'- the fl&2 of char*e' partcles (lo$n o&t fro% the s&n- e2erts a no%nal ')na%c

press&re of a(o&t to 5 nPa- three or'ers of %a*nt&'e less than solar ra'aton press&re on a

reflect!e sal.

. SAIL PARAETERS.1 SAIL LOADING

Sal loa'n* ;areal 'enst)< s an %portant para%eter- $hch s the total %ass '!'e' ()

the sal area- e2presse' n *@%. It s represente' () the Gree0 letter W.

A sal craft has a characterstc acceleraton- ac- $hch t $o&l' e2perence at 1 AU $hen facn*

the s&n. It s relate' to areal 'enst) ()

ac ? 3.: @ W- n %%@s ;ass&%n* =, effcenc)<

. THE LIGHTNESS NUBER- X

The l*htness n&%(er- X- s the '%ensonless rato of %a2%&% !ehcle acceleraton

'!'e' () the s&n7s local *ra!t)> &sn* the !al&es at 1 AU

X ? ac @ :.=

The ta(le presents so%e e2a%ple !al&es. Pa)loa's are not ncl&'e'. The frst t$o are fro% the

'etale' 'es*n effort at "PL n the 1=,s. The thr'- the lattce saler- %*ht represent a(o&t the

(est poss(le perfor%ance le!el. The '%ensons for s8&are an' lattce sals are e'*es. The

'%enson for helo*)ro s (la'e tp to (la'e tp.


http://en.wikipedia.org/wiki/Solar_windhttp://en.wikipedia.org/wiki/Solar_wind


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T)pe W ac X S/e

S8&are sal :. 1.:+ ,.+ 3, %

Helo*)ro +.= 1.= ,. 1: 0%

Lattce saler ,., 11 , 1 0%

Ta(le .1 Sal Para%eters of so%e co%%on sal conf*&ratons

5. ATTITUDE CONTROL

An act!e attt&'e control s)ste% ;ACS< s essental for a sal craft to ache!e an'

%antan a 'esre' orentaton. The re8&re' sal orentaton chan*es slo$l)- often less than 1

'e*ree per 'a)- n nterplanetar) space- (&t %&ch %ore rap'l) n a planetar) or(t. The ACS

%&st (e capa(le of %eetn* these orentaton re8&re%ents.

Control s ache!e' () a relat!e shft (et$een the craft7s center of press&re an' ts center of

%ass. Ths can (e ache!e' $th control !anes- %o!e%ent of n'!'&al sals- %o!e%ent of a

control %ass- or altern* reflect!t).

Hol'n* a constant attt&'e re8&res that the ACS %antan a net tor8&e of /ero on the craft. The

total force an' tor8&e on a sal- or set of sals- s not constant alon* a tra6ector). The force

chan*es $th solar 'stance an' sal an*le- $hch chan*es the (llo$ n the sal an' 'eflects so%e

ele%ents of the s&pportn* str&ct&re- res&ltn* n chan*es n the sal force an' tor8&e.

Sal te%perat&re also chan*es $th solar 'stance an' sal an*le- $hch chan*es sal '%ensons.

The ra'ant heat fro% the sal chan*es the te%perat&re of the s&pportn* str&ct&re. Both factors

affect total force an' tor8&e.

The ACS %&st co%pensate for all of these chan*es for t to hol' the 'esre' attt&'e.


http://en.wikipedia.org/wiki/Center_of_pressure_(fluid_mechanics)http://en.wikipedia.org/wiki/Center_of_pressure_(fluid_mechanics)http://en.wikipedia.org/wiki/Center_of_masshttp://en.wikipedia.org/wiki/Center_of_masshttp://en.wikipedia.org/wiki/Center_of_masshttp://en.wikipedia.org/wiki/Center_of_pressure_(fluid_mechanics)http://en.wikipedia.org/wiki/Center_of_masshttp://en.wikipedia.org/wiki/Center_of_mass


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:. SOLAR SAIL OPERATIONS

:.1 CHANGING ORBITS

Saln* operatons are s%plest n nterplanetar) or(ts- $here attt&'e chan*es are 'one at

lo$ rates. 9or o&t$ar' (o&n' tra6ectores- the sal force !ector s orente' for$ar' of the S&n

lne- $hch ncreases or(tal ener*) an' an*&lar %o%ent&%- res&ltn* n the craft %o!n* farther

fro% the S&n. 9or n$ar' tra6ectores- the sal force !ector s orente' (ehn' the S&n lne- $hch

'ecreases or(tal ener*) an' an*&lar %o%ent&%- res&ltn* n the craft %o!n* n to$ar' the S&n.

It s $orth notn* that onl) the S&n7s *ra!t) p&lls the craft to$ar' the S&nYthere s no analo* to

a sal(oat7s tac0n* to $n'$ar'. To chan*e or(tal nclnaton- the force !ector s t&rne' o&t of

the plane of the !eloct) !ector.

In or(ts aro&n' planets or other (o'es- the sal s orente' so that ts force !ector has a

co%ponent alon* the !eloct) !ector- ether n the 'recton of %oton for an o&t$ar' spral- or

a*anst the 'recton of %oton for an n$ar' spral.

Tra6ector) opt%/atons can often re8&re nter!als of re'&ce' or /ero thr&st. Ths can (e

ache!e' () rolln* the craft aro&n' the s&n lne $th the sal set at an approprate an*le to re'&ce

or re%o!e the thr&st.

:. SINGBZS

A close solar passa*e can (e &se' to ncrease a craft7s ener*). The ncrease' ra'aton

press&re co%(nes $th the effcac) of (en* 'eep n the s&n7s *ra!t) $ell to s&(stantall)

ncrease the ener*) for r&ns to the o&ter solar s)ste%. The opt%al approach to the s&n s 'one ()

ncreasn* the or(tal eccentrct) $hle 0eepn* the ener*) le!el as h*h as practcal. The

%n%&% approach 'stance s a f&ncton of sal an*le- ther%al propertes of the sal an' other

str&ct&re- loa' effects on str&ct&re- an' sal optcal characterstcs ;reflect!t) an' e%ss!t)


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A l&nar s$n*() can ha!e %portant (enefts for tra6ectores lea!n* fro% or arr!n* at

Earth. Ths can re'&ce trp t%es- especall) n cases $here the sal s hea!l) loa'e'. A s$n*()

can also (e &se' to o(tan fa!ora(le 'epart&re or arr!al 'rectons relat!e to Earth.

A planetar) s$n*() co&l' also (e e%plo)e' s%lar to $hat s 'one $th coastn*

spacecraft- (&t *oo' al*n%ents %*ht not e2st '&e to the re8&re%ents for o!erall opt%/aton

of the tra6ector).

:. SART LINES

A s%art lne co&l' (e a crtcal ele%ent of saln* operatons. As $th %art%e shps-

lnes are essental for a $'e ran*e of &ses. One 'fference s that so%e lnes %a) (e !er) lon*

an' nee' to (e self*&'n*. The lnes co&l' e2ten' fro% an' retract nto the sal craft.

A %ane&!era(le *rappln* 'e!ce can (e &se' at the en' of a lne to place or pc0 &p

pa)loa' contaners- to sec&re a shp to a str&ct&re s&ch as a staton- to pc0 &p sa%ples fro% an

astero' or co%et- or to en*a*e n to$n*. The %ane&!ern* &nt s l0e a s%all spacecraft- $th

%an) of the sa%e sensors an' control s)ste%s. It co&l' 'ra$ po$er fro% an' co%%&ncate $th

the sal craft thro&*h the lne. These operatons co&l' (e 'one a&tono%o&sl).

Lnes a fe$ h&n're' 0lo%eters lon* %a) (e &se' to %o!e a shp fro% a space staton to an or(t

farther o&t $here t co&l' (e*n saln*.

:.5 TOING

S%art lnes can ena(le to$n* operatons () (en* a(le to attach to or release o(6ects at

the re%ote en' of the lne. Attache' o(6ects %*ht (e p&lle' n to the (o') of the saler or re%an

at the en' of the 'eplo)e' lne. O(6ects to (e to$e' %a) ha!e attach%ent ponts that allo$

%&ltple sal craft to en*a*e n the to$n*. To$n* operatons can ncl&'e 'eflectn* lar*e (o'es

that pose a ha/ar' to Earth- (rn*n* nat&ral (o'es to Earth or other stes for reso&rce reco!er)-

an' transportn* 'sa(le' spacecraft or other str&ct&res.



14/25


To to$ or 'eflect a lar*e (o')- poles can (e nserte' on the spn a2s of the (o'). Sal

craft can attach to the e%(e''e' poles &sn* s%art lnes. Slp rn*s ena(le the craft to to$

$tho&t the lnes *ettn* $rappe' &p as a res&lt of rotaton of the (o').

:.: OPERATION CONSTRAINTS

In Earth or(t- solar press&re an' 'ra* press&re are t)pcall) e8&al at an altt&'e of a(o&t

3,, 0%- $hch %eans that a sal craft $o&l' ha!e to operate a(o!e that altt&'e. Sal craft %&st

operate n or(ts $here ther t&rn rates are co%pat(le $th the or(ts- $hch s *enerall) a

concern onl) for spnnn* 's0 conf*&ratons.

Sal operatn* te%perat&res are a f&ncton of solar 'stance- sal an*le- reflect!t)- an'

front an' (ac0 e%ss!tes. A sal can (e &se' onl) $here ts te%perat&re s 0ept $thn ts

%ateral l%ts. Generall)- a sal can (e &se' rather close to the s&n- aro&n' ,.: AU- or e!en

closer f caref&ll) 'es*ne' for those con'tons.

+. SOLAR SAIL CONSTRUCTION

The %ateral 'e!elope' for the Dre2ler solar sal $as a thn al&%n&% fl% $th a

(aselne thc0ness of ,.1 [%- to (e fa(rcate' () !apor 'eposton n a space(ase' s)ste%.

Dre2ler &se' a s%lar process to prepare fl%s on the *ro&n'. As antcpate'- these fl%s

'e%onstrate' a'e8&ate stren*th an' ro(&stness for han'ln* n the la(orator) an' for &se n

space- (&t not for fol'n*- la&nch- an' 'eplo)%ent.

The %ost co%%on %ateral n c&rrent 'es*ns s al&%n/e' [% #apton fl%. It ressts

the heat of a pass close to the S&n an' stll re%ans reasona(l) stron*. The al&%n&% reflectn*

fl% s on the S&n s'e. The sals of Cos%os 1 $ere %a'e of al&%n/e' PET fl% ;)lar


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In ,,,- Ener*) Scence La(oratores 'e!elope' a ne$ car(on f(er %ateral that %*ht

(e &sef&l for solar sals. The %ateral s o!er ,, t%es thc0er than con!entonal solar sal

'es*ns- (&t t s so poro&s that t has the sa%e %ass. The r*'t) an' '&ra(lt) of ths %ateral

co&l' %a0e solar sals that are s*nfcantl) st&r'er than plastc fl%s. The %ateral co&l' self

'eplo) an' sho&l' $thstan' h*her te%perat&res.

There has (een so%e theoretcal spec&laton a(o&t &sn* %olec&lar %an&fact&rn*

techn8&es to create a'!ance'- stron*- h)perl*ht sal %ateral- (ase' on nanot&(e %esh $ea!es-

$here the $ea!e spaces are less than half the $a!elen*th of l*ht %pn*n* on the sal. hle

s&ch %aterals ha!e so far onl) (een pro'&ce' n la(orator) con'tons- an' the %eans for

%an&fact&rn* s&ch %ateral on an n'&stral scale are not )et a!ala(le- s&ch %aterals co&l'

%ass less than ,.1 *@%- %a0n* the% l*hter than an) c&rrent sal %ateral () a factor of at least

,. 9or co%parson- : %cro%etre thc0 )lar sal %ateral %ass *@%- al&%n/e' #apton

fl%s ha!e a %ass as %&ch as 1 *@% an' Ener*) Scence La(oratores7 ne$ car(on f(er

%ateral %asses *@%.

The least 'ense %etal s lth&%- a(o&t : t%es less 'ense than al&%n&%. 9resh-

&no2'/e' s&rfaces are reflect!e. At a thc0ness of , n%- lth&% has an areal 'enst) of

,.,11 *@%. A h*hperfor%ance sal co&l' (e %a'e of lth&% alone at , n% ;no e%sson

la)er


16/25


In the f&t&re- fa(rcaton co&l' ta0e place n or(t ns'e lar*e fra%es that s&pport the sal.

Ths $o&l' res&lt n lo$er %ass sals an' el%naton of the rs0 of 'eplo)%ent fal&re.

. SOLAR SAIL PRO"ECTS

.1 I#AROS ,1,

9* .1 The %o'el of I#AROS at the +1st Internatonal Astrona&tcal Con*ress n ,1,

"apan7s "A\A s&ccessf&ll) teste' I#AROS n ,1,. The *oal $as to 'eplo) an' control

the sal an' for the frst t%e 'eter%nn* the %n&te or(t pert&r(atons ca&se' () l*ht

press&re. Or(t 'eter%naton $as 'one () the near() A#ATSU#I pro(e fro% $hch

I#AROS 'etache' after (oth ha' (een (ro&*ht nto a transfer or(t to Ven&s. The total effect

o!er the s2 %onth7 fl*ht $as 1,, %@s.

Untl ,1,- no solar sals ha' (een s&ccessf&ll) &se' n space as pr%ar) prop&lson

s)ste%s. On 1 a) ,1,- the "apan Aerospace E2ploraton A*enc) ;"A\A< la&nche'

the I#AROS ;Interplanetar) #tecraft Accelerate' () Ra'aton Of the S&n< spacecraft-

$hch 'eplo)e' a ,, % pol)%'e e2per%ental solar sal on "&ne 1,. In "&l)- the ne2t

phase for the 'e%onstraton of acceleraton () ra'aton (e*an. On = "&l) ,1,- t $as

!erfe' that I#AROS collecte' ra'aton fro% the S&n an' (e*an photon acceleraton () the

or(t 'eter%naton of I#AROS () ran*ean'ran*erate ;RARR< that s ne$l) calc&late' n

a''ton to the 'ata of the relat!saton acceleratn* spee' of I#AROS (et$een I#AROS

an' the Earth that has (een ta0en snce (efore the Doppler effect $as &tl/e'. The 'ata

sho$e' that I#AROS appears to ha!e (een solarsaln*.



17/25


I#AROS has a 'a*onal spnnn* s8&are sal , % ;++ ft< %a'e of a .:%cro%etre

;,.,,: %%< thc0 sheet of pol)%'e. The pol)%'e sheet ha' a %ass of a(o&t 1, *ra%s

per s8&are %etre. A thnfl% solar arra) s e%(e''e' n the sal. E*ht LCD panels are

e%(e''e' n the sal- $hose reflectance can (e a'6&ste' for attt&'e control. I#AROS spent

s2 %onths tra!eln* to Ven&s- an' then (e*an a three)ear 6o&rne) to the far s'e of the S&n.

. NANOSAILD ,1,

9*. NanoSalD of L*htSal1 $th sal 'eplo)e'

A tea% fro% the NASA arshall Space 9l*ht Center ;arshall


18/25


reporte'l) pro'&ce' a $ealth of 'ata concernn* the &se of solar sals as pass!e 'eor(t

'e!ces.

. SAIL DEPLOZENT TESTS BZ NASA

NASA has s&ccessf&ll) teste' 'eplo)%ent technolo*es on s%all scale sals n !ac&&%

cha%(ers. In 1===- a f&llscale 'eplo)%ent of a solar sal $as teste' on the *ro&n' at

DLR@ESA n Colo*ne.

On A&*&st =- ,,5- the "apanese ISAS s&ccessf&ll) 'eplo)e' t$o protot)pe solar sals

fro% a so&n'n* roc0et. A clo!ershape' sal $as 'eplo)e' at 1 0% altt&'e an' a fan

shape' sal $as 'eplo)e' at 1+= 0% altt&'e. Both sals &se' .:%cro%eter fl%. The

e2per%ent p&rel) teste' the 'eplo)%ent %echans%s- not prop&lson.

A 6ont pr!ate pro6ect (et$een Planetar) Socet)- Cos%os St&'os an' R&ssan Aca'e%)

of Scence %a'e t$o sal testn* atte%pts n ,,1 a s&(or(tal protot)pe test fale' (eca&se

of roc0et fal&re> an' n "&ne 1- ,,:- Cos%os 1 la&nche' fro% a s&(%arne n the Barents

Sea- (&t the Volna roc0et fale'- an' the spacecraft fale' to reach or(t. The) nten'e' to &se

the sal to *ra'&all) rase the spacecraft to a h*her Earth or(t o!er %sson '&raton of one

%onth. On Carl Sa*an7s :th (rth'a) ;No!e%(er =- ,,=< the sa%e *ro&p anno&nce' plans

to %a0e three f&rther atte%pts- '&((e' L*htSal1- - an' . The ne$ 'es*n $ll &se a

s8&are%eter )lar sal- 'eplo)e' n fo&r tran*&lar se*%ents l0e NanoSalD. The

la&nch conf*&raton s that of three a'6acent C&(eSats- an' as of ,11 $as $atn* for a

p**)(ac0 la&nch opport&nt).

A 1:%eter'a%eter solar sal $as la&nche' to*ether $th ASTRO9 on aV roc0et on

9e(r&ar) 1- ,,+- an' %a'e t to or(t. It 'eplo)e' fro% the sta*e- (&t opene' nco%pletel)

Solar sal la&nchn* pro6ects n ,1, an' ,11

On 1 a) ,1,- "apan Aerospace E2ploraton A*enc) ;"a2a< la&nche'

the $orl'7s frst nterplanetar) solar sal spacecraft I#AROS to Ven&s. + NASA la&nche'

the secon' NanoSalD &nt sto$e' ns'e the 9ASTSAT satellte on the nota&r IV on

No!e%(er 1=- ,1,. The e6ecton 'ate fro% the 9ASTSAT %crosatellte $as planne' for

Dece%(er +- ,1,- (&t 'eplo)%ent onl) occ&rre' on "an&ar) ,- ,11. + The Planetar)

Socet) of the Unte' States plans to la&nch an artfcal satellte L*htSal1 onto the

DEPT OF AERO MZC KADAMMANITTA Page 1"

http://en.wikipedia.org/wiki/Worldhttp://en.wikipedia.org/wiki/Interplanetary_spaceflighthttp://en.wikipedia.org/wiki/Solar_sail#cite_note-62http://en.wikipedia.org/wiki/NASAhttp://en.wikipedia.org/wiki/Solar_sail#cite_note-63http://en.wikipedia.org/wiki/The_Planetary_Societyhttp://en.wikipedia.org/wiki/The_Planetary_Societyhttp://en.wikipedia.org/wiki/The_Planetary_Societyhttp://en.wikipedia.org/wiki/The_United_Stateshttp://en.wikipedia.org/wiki/The_United_Stateshttp://en.wikipedia.org/wiki/Artificial_satellitehttp://en.wikipedia.org/wiki/LightSail-1http://en.wikipedia.org/wiki/The_Earthhttp://en.wikipedia.org/wiki/The_Earthhttp://en.wikipedia.org/wiki/Worldhttp://en.wikipedia.org/wiki/Interplanetary_spaceflighthttp://en.wikipedia.org/wiki/Solar_sail#cite_note-62http://en.wikipedia.org/wiki/NASAhttp://en.wikipedia.org/wiki/Solar_sail#cite_note-63http://en.wikipedia.org/wiki/The_Planetary_Societyhttp://en.wikipedia.org/wiki/The_Planetary_Societyhttp://en.wikipedia.org/wiki/The_United_Stateshttp://en.wikipedia.org/wiki/Artificial_satellitehttp://en.wikipedia.org/wiki/LightSail-1http://en.wikipedia.org/wiki/The_Earth


19/25


Earth7s or(t n ,11. Despte the losses of Cos%os 1 an' NanoSalD ;$hch $ere '&e to

fal&re of ther la&nchers


20/25


3.1 INNER PLANETS

9or trps $thn the nner solar s)ste%- the) can 'el!er loa's an' then ret&rn to Earth for

s&(se8&ent !o)a*es- operatn* as an nterplanetar) sh&ttle. 9or ars n partc&lar- the craft

co&l' pro!'e econo%cal %eans of ro&tnel) s&ppl)n* operatons on the planet.

Solar sal craft can approach the s&n to 'el!er o(ser!aton pa)loa's or to ta0e &p staton

0eepn* or(ts. The) can operate at ,.: AU or closer. The) can reach h*h or(tal

nclnatons- ncl&'n* polar.

Solar sals can tra!el to an' fro% all of the nner planets. Trps to erc&r) an' Ven&s are

for ren'e/!o&s an' or(t entr) for the pa)loa'. Trps to ars co&l' (e ether for ren'e/!o&s

or s$n*() $th release of the pa)loa' for aero')na%c (ra0n*.

Ta(le 3.1 Propose' sal para%eters for !aro&s nner planet %ssons

3. OUTER PLANETS

n%&% transfer t%es to the o&ter planets (eneft fro% &sn* an n'rect transfer ;solar s$n*()


21/25


arr!al spee' ;V]< s close to 1 0%@s. 9or Sat&rn- the %n%&% trp t%e s . )ears- $th

an arr!al spee' of nearl) 1= 0%@s.

"&pter Sat&rn Uran&s Nept&ne

T%e-

)r ., . :.3 3.:

Spee'

- 0%@s1 1= , ,

Ta(le 3. n%&% t%e for o&ter planet %ssons

3. OORT CLOUD

A s%all tea% has propose' a (er)ll&% nflate' sal that $o&l' *o 'o$n to ,.,: AU fro%

the s&n n or'er to *et an acceleraton pea0n* at +.5 %@s - reachn* a spee' of ,.,,+5c ;a(o&t

=:, 0%@s< n less than a 'a). S&ch a sal $o&l' ta0e t$o an' a half )ears to reach the helopa&se-

s2 an' a half )ears to *et to the S&nJs nner *ra!tatonal foc&s ;::, AU


22/25


are statonar) $th respect to ether the S&n or the Earth- a t)pe of satellte na%e' () 9or$ar'

a statte. Ths s poss(le (eca&se the prop&lson pro!'e' () the sal offsets the *ra!tatonal

potental of the S&n. S&ch an or(t co&l' (e &sef&l for st&')n* the propertes of the S&n o!er

lon* '&ratons.

S&ch a spacecraft co&l' conce!a(l) (e place' 'rectl) o!er a pole of the S&n- an' re%an

at that staton for len*th) '&ratons. L0e$se a solar sale8&ppe' spacecraft co&l' also re%an

on staton nearl) a(o!e the polar ter%nator of a planet s&ch as the Earth () tltn* the sal at the

approprate an*le nee'e' to 6&st co&nteract the planet7s *ra!t).

In hs (oo0 The Case for ars- Ro(ert &(rn ponts o&t that the reflecte' s&nl*ht fro% a

lar*e statte place' near the polar ter%nator of the planet ars co&l' (e foc&se' on one of the

artan polar ce caps to s*nfcantl) $ar% the planet7s at%osphere. S&ch a statte co&l' (e

%a'e fro% astero' %ateral.

3.: TRA"ECTORZ CORRECTIONS

The ESSENGER pro(e or(tn* erc&r) &se' l*ht press&re on ts solar panels to

perfor% fne tra6ector) correctons on the $a) to erc&r). B) chan*n* the an*le of the solar

panels relat!e to the S&n- the a%o&nt of solar ra'aton press&re $as !are' to a'6&st the

spacecraft tra6ector) %ore 'elcatel) than poss(le $th thr&sters. nor errors are *reatl)

a%plfe' () *ra!t) assst %ane&!ers- so &sn* ra'aton press&re to %a0e !er) s%all correctons

sa!e' lar*e a%o&nts of propellant.

3.+ DEORBITING ARTI9ICIAL SATELLITES

S%all solar sals ha!e (een propose' to accelerate the 'eor(tn* of s%all artfcal satelltes

fro% Earth or(ts. Satelltes n lo$ Earth or(t can &se a co%(naton of solar press&re on the sal

an' ncrease' at%ospherc 'ra* to accelerate satellte reentr).



23/25


= ADVANTAGES AND DISADVANTAGES

A'!anta*es

1. No nee' to carr) an) f&el. Hence t has h*her effcenc) $hen co%pare' to other

prop&lson s)ste%s.

. S%ple 'es*n an' concept.

. S&ta(le for nterplanetar) an' nterstellar !o)a*es.

Dsa'!anta*es

1. Can onl) (e &se' fro% altt&'es h*her than 3,, 0%s '&e to the opposn* effect of the

ar 'ra*.

. Deplo)%ent of the sals of the sal s a co%plcate' process.

. ane&!era(lt) s e2tre%el) lo$ $tho&t the s&pport of po$erf&l a&2lar)

prop&lson 'e!ces.

1,. CONCLUSION

9or nterplanetar) tra!el that re8&res e!en farther 'stances- the solar sal has (een

propose' as a pro%sn* technolo*) to ache!e t. Solar sal stan's as one of the %ost

realstc optons for nterplanetar) an' e!en nter*alactc tra!el- as t el%nates (oth roc0et

f&el an' roc0et en*nes that ha!e (een l%tn* space tra!el &ntl no$. In the solar sal

po$ere' spacecraft- (oth the roc0et f&el an' en*ne are replace' $th sals that are po$ere'

() the s&nJs constant press&re of photons. The sals are %a'e of reflect!e %ateral that has

the s&nl*htJs photons (o&nce off of t> as these l*ht partcles (o&nce off the %rrorl0e sal-



24/25


the) transfer ther %o%ent&% to the sal to n&'*e t alon*. As for the force of ths n&'*e- t s

tr&e that the force on a solarsal spacecraft s far less than a con!entonal che%cal roc0et

l0e the space sh&ttle. In the 'stance that the Earth has fro% the s&n ;1:, %llon 0%- or 1

AU


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seminar report part 2

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