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TACSAT-SPACECRAFT BUS CONCEPT AND DESIGN:
APPLICATION OF A MULTIMISSION BUS FOR TACSAT IN LEO
FROM A FEW LARGE SOPHISTICATED
SATELLITES ...
Bcforc describing thc way, a low carth orbit
multimission Bus for tactic;rl application is
dcsigncd, it is convcnicnt t,u ;in;ilysc in soti'c
dctails w1i;it is a tactical s;itcllitc ns far as sur h
satcllitcs arc vcry oftcn associated with tlic
notion of chcap sniall satcllitcs.
For 30 yc;irs tlic six, thc ni;iss. the coniplcxity,
and the cost of thc satcllitcs haw hrcn
incrcasing. Spacc prograninics, cspccially in tlic
dclcncc arca, tend to usc hcavy ancl costly
satcllitcs in a too small nunibcr of spccinicns
comparcd with thc nccds of uscrs, thcy havc
thcn to continuously monitor priority conflicts
such as : budgctary conflicts to dccidc which
programnic has priori!y, opcratioii;d usc
conflicts whcn programming tlic niissinns of so
Tcw spacccrafts.
In thc tnday contcxt of budgctary coiistr:iints,
raising again is thc wcll known syndrome "oiic
aircraft, onc tank, onc satellite as uniquc fu!urc
-equip ni c n t for dc fc n cc'.
Thc spacccrafis number liniitation is thc
conscqucncc of an inflationist spiral which can
bc dcscribcd in lhrcc stages :
a - unit cost incrcascs
by
Gcorges Richard
Matra Marconi
Espacc/Dircction dcs Programmes Militaires
2.1. du Palays-RUC des Cosmonautcs
I
31077 Toulousc
Frnncc
b - thcn for a givcn budget, numbcr of
opcrational units dccrcascs
c - a lirnitcd number of spacccrafts lcads to
pusch for mission optimitation with :
- an incrcasc of in orbit lifc timc and rcliability
rcquircnlcnts
- tlir nccd lo group scvcral niissions on thc
S;I 111 c spa cc c ra ft.
- kxIini:*al sophistication
- conscrvativc approach includiiig rncticulous
:l~:vclopmcnt and compicx vcrifications
- no risk approach, as thc unit cost of cach
satcllitc is such a high stakc
All thcsc points lcad to unit cost incrcasc and
\)ring back to st;igc n iii tlic iiifl;itionist spiral.
... TO CONSTELLATIONS OF NUMEROUS
CIIEAP LIGIITSATS
To brcak this spiral, somc cxpcrts sugcst a
"Smart small clicap lightsats" conccpt. Thcir
main idca is to drastically dccrcasc thc unit cost
of thc spacccraft in orbit, this cost including thc
satcllitc recurring cost itsclf, (hc launch cost and
thc ground scgnicnt and opcrations costs.
This conccp! is consistcnt with a system
archi~cctiirc using constcllations of nunicrous
satcllitcs oC liniitcd in orbit lifc timc and low