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1. INTRODUCTION
Attitude- and Orbit Cootrol Subsystem Concepts for TACSATS
The technical pcrforrnancc spccifications ;ind
rcquircrncnts for Attitude- and 01 lit Control
Subsystcrns (AOCS) for satcllitcs arc Jictatcd by n
large numbcr of boundary conditions:
- The payload rcquircrncntS (c.g. poiiitiny accura-
cy, LOS-stabiliLy)
- Thc perturbation cnvironrncnt. Imh caernal
and intcrnal, i.c.:
Gravitational-, solar prcssurc-. air dras-, rna-
gnctic disturbancc torcjucs
Rcaction jets, whccl wobhlc, payload opcra-
tion
. - Easc of opcrability (command structure and scqucnccs)
- Onhoard autonomy (cornm;ind-. clilta and cornmunication
links)
- Opcrational lifc tirnc / rcliabilitv
- Maintainability, storahi!tv ant1 so on
For the class of spacccraft undcr discussion hcrc.
mass limitations. which will not allow major orbit
changes. and thc diffcrcnt typcs of pny1o;ids for
survcillancc. vcrification and C31 as well 3s str;itc-
gic aspccts call for cxtrcrncly high flcnbility ol' thc
AOCS-concept IO enable:
- 'Last minute * sclcction of the opcraiional or-
-
bits according to the actual nccd
Adaptation to the rcquircrncnts of diffcrcnt
typcs of payloads (passivc: Optical. infrarcd;
active: k-wave)
- Compatibility with a Iwgc dynamic rangc oi
plant pararnctcrs (e.g. largc / small solar arrays
and structural flexibility dcpcnding on clcctrical
power requirement)
H.l'!ittner, E.Briiderlc
MSvraucr, MSchwcnde
DASA/MIBB
Space Comm. and Prop. Syst.Div.
D 8OOO MUNCHEN 80. P.O.Box 801169
Modularity of the AOCS in tcrms of typc and ar-
rangcrncnt of cquipmcnt. (sensors, actuators),
control laws and operational scqucnccs (OBC-capa-
city and algorithms) thcrcforc has to be a prcdo-
rninant fcaturc. It is cxpcctcd thar the flexibility for
adaptation to spccific mission requirerncnts and thc
rn.duluity of thc AOC subsystcm cnvisagcd will
contributc to a low cost but still highly efficient
tactical satcllitc systcm.
On thc basis of cxpcricncc in Attitudc- and Orbit
Control Systcrn dcsign, analysis, acccptance tcsting,
and in-orbit opcrations support for communication
satcllitcs (INTEISAT V, TV-SATRDF, TELE-X.
DFS-KOPERNIKUS. EUTELSAT II), earth OIJSCr-
vation satcllitcs (MOS-I. ATMOS), and scientific
satcllitcs (ROSAT, EURECA. ASTRO-SPAS).
suitablc AOCS-concepts arc discusscd in thc papcr.
2. REQUiREhlENTS AND CONSTRAINTS
In addition to scniccs alrcadv gcricraliy available.
tactical satcllitcs of the typc in quc::ion hcrc arc
supposed to provide on sbon noticc and particular
rcqucst irnprovcd and cfficicnt scrviccs in at Icact
onc. prcfcrrably scvcral of thc following fivc mi;sion
arcns:
- communic:itions, e.g. from. to md bctwccn
mobile units on ground or bctwccn satcllitcs
- wcn:hcr, i.c. dctilcd actual wcathcr conditions
and prediction in dcfinitc local weas
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