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3.2 P A tuimira ~ ok c~,~~a~aellonaorbiea
po~a~oto~o
An inceoonlng numbar of omall oatollrtoa
conaeollationo IQ being propcowl (a] for
advancod comnunication and renoto noneinq
applicntiono: aost conotollatlono havo
nultlplo natollltes in ono ou Rultiplo
orbltoll plonoa: low altItubo onbito,
typically 000 to 1900 Km, Q ~ O
noentally
envioacgod, with a few c e~eo conoidoritq
altitudloe, as hlqh as loOD0 Kn.
Wi8nag!?Q thQW.7 COmpl€?X SyUeemS Will
xoquirs copylng vIth tho launch nystenn
orbit injoction disporniona, 8s wQlt ibo
m$intainingl eh0 satallitao relative
pRoobng durIngl the orbleal lieeelno
atpinot oneornnl distuubsncna. Tho
qhntiaation of these eefacea, in eerrns oe
propolllone amso, doponde stroqly from tho
launch wohicle cha~actoriatico, orble typ
and oloalon duration, and vlbll not bo
nttorslptcd ~QE~P. Tho gush towouch launch
coat sduction ~lqht probably lqly, in
tho nwor Puturo, the usa of looa nccueaee
L.V. a d groator injection Bioporoiona.
There Lo a100 a clear trend to require
longer orbital lifetinos.
-eh Pnceoro vi11 tend to Incr@ase tho
propellant mass allocated ffor orbit
control: ehis vi11 impact nqcntivsrly tho
oyatoa ocononico, also in view of th0
multiplying oeeoct due to tho Iti~ge number
oc ooeolliesa In those conotallations.
Clectrlc propulsion may be connldorod in
alt~rnetlva to chamlcal propulalon for tho
potsntlol masdl naving it1, can provldo,
spoclollly in presence ol hlqh orbie
Injoction dloprolons and loncg orbital
'ilotimo. ConetollatIon phaobncg is not a
tino-llaitod propulsion task, whlch will
enablo uah9 low thrust, high speclfic
iFiYpI1b0, C.P. syetoms. suitable neraeogiee
for conneallation phasing msineananca can
be concoivod, poesibly aided by nutonomous
navigatlon systems, to fully exploit the
E.P. characteristics.
Stuall oetollites in qooetationary orbit
can poreorm useful1 conntrnication,
meteo~ological and observation mlnsiono.
Clusters of two to four npacncraft can
form a Bietributed satelllte syatem havlng
enhanced performance w.r.t. 61 single
Aatollite of an identical total mass.
Assuainq the availability of a launch
vehicle capable of d:rectly injecting the
saesllieos in synchronoue orbit (such as,
Q.Q. tho Ruesian Proton rock&) small
sgacocrale relying exclusively on E.P. can
be concoivced.
The absence of a bulky apoqee motor
greatly ex>anda the spacecraee design
freodon, including the positioning and
orisntaeion, or canting angle, of tha E.P.
thrustera. Spacecraft incorporating
eevoPa1 ne6111 thrusters may impl@nent both
orbit Control and entornc;lll torquo.
cospnsation for attitude control.
Tabto s.3.-1 qlivoo tho eeorontisls oP em
Bniithol ccancopt Pou a high prfonaanco
onell goootaeionery eatallite. Basic
Boaturea nra tho low potfer/lov thrust ionthrustera,
tho reouleing overall low E.P.
OY~P~~PR moo, tho high ach'wable payload
to oatslllte launch mass ratio, the
eboonco of any kInd of .chemical
propulsion.
Satollito launch mass (Kq):
Q Payload aass (Kg)
* Payloed/launch,mass ratio :
Orbital lifetime, years :
Wqrd. total velocity
incromene (ra/n) W-SIS. K. .:
E-W/S.K.:
Ion thruotors nurnbQr
'FhrUQt 169VelS(W) w-s/s.E(.:
E-U/S.K.:
Q Total prop.rncPse (Kg)
Avge dayly thrusting time
N-S/S.K.:
E-W/S.K. :
4 E.B. oyoten einm (K9)
* E.P. peak DC power (W) :
Q Deyly e.rergy nosdsIKWh) :
Foaoiblr! control torques
in pitch,roll,yev
600
240
> 0,4
15
700
70
10 to 12
OmN (2.4mN)
4mN (2.2mN)
< 18
2.66 hour8
32 min.
YO (est.)
240
0.7