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Thoro are sovoral additlonal positive, and neqativo factors, to bo V.T)ten ' into acccrunt, vhlch may affect thn trip time: but in conclusion the PMslbiltty of usinq low power arcjets irl potmr limited liqhtante Cor lov altitudo circular to elliptical orbits coplanar trennfers ha0 to be considered still problemntic. 3.6 o~b_lc~-ci rcu la r i LA t Ion- Thio propulsion task refers to sdtellituo, injected in elliptical transfer orbit by a I..v., whom final dentination otbit is circular with a radius normally coincident vith the T.O. aygee. Typica1 cases are goostatlonary orbits anti medium altitude circular orbits of about 10000 Km as envlSm$@d, for example, by TRW's Odyssey and ESh'o MGSS-14 constellntion [5). Electric propulsion is ~onpnrcd to chemical in Tnble 3.6-1. for thnno tua typical mlsnions. Arcjetn nre found to perform acceptably well in this case, olnco trlp tlmos around 200 dayn cnn be achieved lony with niqniflcant mass oav,Inqn w.r.t. a chmlcal propulsion alternative. The bQttQr mnsn envinq achievable with SPTs Is, Instead, piid wlth an excessive trip t inn dur;rt Lon. ___.I_____.. --_.--.-. ..."..-. . - -.- _.-.I 4. T.0. chnracterlstlcn: - Periqee (Kn) C679 6778 - Apqao (Kn) 42164 I 7 2 M ** DostInation Orbit characteristics: - Radius (Km) 42164 16728 - Voloclty incromont, idartl trnnnf.(a/s): 1476 1174 ** T. 0. mass/propel 1 . miss (W) (1)(2): - chnnlcal R44/144 '1 G o/ 2 6 0 - arcjet 700/200 655/155 - SPT 555/55 544/ 14 *4 Trip tines (days): ' - - chenlcal /1 1 arcjet 227 1R2 - SPT n.a. 453 Note I): Satellite drymase 500 Kq; " 2): Including a 15\ increnno In delta velocity due to non-Ideal tranfern Table 3.6-1 E.P. alternativee for Orbit C1 rcular I zat ion , 4,RE;'XEW OF SYSTEM NEEDS Prom thip ovorviev two E; P. technologies appbar to have a future 'on power limited lightsnts: - small ion thrusters for drag compensation, limltod orbit raining, orbit circularization and fine trlmming of orbital parameters of small satellites. The required thrust lov0lo ara in tho 2 to 10 mN range. a modular approach anablinq parallol operation oP thruetcra is also required. Full thrust control, over a 30% to 120 a range of the design thrust leveA, is an important design requirement. An Ovorall specific power of 40 w/mN maximum (30 W/mN as a goal), and a spoclPir: system mass of less than 1 Kq/mN maximum (0.7 Kg/mN as a goal), including power supply 24-5 end lgic should be sot as near tern dovo~oprnont objectives. Isp valuos bettor than 3609 sec., and very .on9 lifetimes, aP the ordar of 40000 houra, are also pr imary roqu ironenta: - IOW QOWQr arCjOtS in the I to 1.2 KW ranqe. for orbit mnnoeuverinq tnnks. For such UOVICQS oflorts should tn! dcvotcd to possibly brlnq the Isp closer to 600 sec. for thrusts in the 150 to 2r~0 nl.J ranqe, vith an overall speci:ic pover better than 8 W/mN includinq power supply. On the other hand stationary plasma thrusters do not Seem to have a clear role for liqhtsats, at least in their present power and thrust level ranqe. Scaling down SPTS to lov thrust vnluos (say below io nl'), while keeping unchanged thnir ex:ellent parformance, in particular efficiency and simplicity, is yet unproven but miqht be worth beinq investlqatcd. For the considered thru-t ranfin, new devices bused on tho Electron Cyclotron Resonanco (ECR) (2) are presently under evnluation, nimfnq to further improve the 1 on thruster's per formancc . The ECR tect iiquo nllowe oporatinq over a vider thrust ranqe by chanqing the mass flow rate in tho diocharqa ch;imber enhancing the electrlcal efficiency and qaa conoumption over a widor pressure ranqo than tho conventlonnl RF nnd Knufman techno 1 oq les . pn r t 1 cu 1 n r 1 y ECR appears indicated for sinal: sIz@ Ion thrusters, for which it io aloo onaler to achieve the optimum static maqnotlc flold necessary for resonance. The ECH technique consists in applying a ntatlc magnetlc field I orthoqonal to the direction of an oscillating RF field, so that electrons are forcod to rotate within the thruster's discharqe chamber, around the magnetic field lines at a cyclotron frequency givon by: Fc- eB/2nm. The mean energy per collision, transferred to an electron, is: Wc- (e*E1/4m)(1/(4nI (F-Fc)+(l/il)), with: 0- magnetic Pield; e- olectron charqo: m- electron mass; E- applied electric field peak amplitude: 7- mean time between two consecutive collisions, inversely proportional to gas pressuro; F- frequerlcy of the appliod RF field. At re60nance F=Fc, and the quantity WC assumes its maximuin value: Wc - (cEi)'/4m, which depends only on collision interval and electric field peak value. Clearly the maximum bonoeitn of tho ECR effoct is achieved in the low presouro ranqo, being the col~ision fi-squency proportional to the operating qas pessure. For a ion propulsion system in the millinowton range a RP excitation in the V"p range proves advantageous for the rollovinq considerations:
I I ! I i ~ I I I I I I I ! I I I I i I I I I I 0' I I I I I I I I I I I I I I I I I .eI I I I I I I I I I ' I I ! I I I I I I I I I I I
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ADVISORY GROUP FOR AEROSPACE RESEAR
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Acccorclinp tto 11s C”liirlcr. th
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0 Im oyi.rationr rcccntc\ *Tcm+tc d
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Theme 'fieme 0 - 0 Avionics Pencl a
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-- Printed in Clawificcl puhlicatio
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1'. 2 c From tplc four pafcn. thcrc
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Talcs. Thc lcchnology emphasis wnr
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These arc three spccific fecornmen&
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when WO Rave gone from one'modsl sa
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3-4 mggd and easily operated. This
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3-6 interim capability should one o
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OI~UI'IS MISSIONS I PAYLOAD TYPE -.
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1 Int raduction The iiotcntial cxpl
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indicated hat an IR vcrsion of the
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a 0 Annex A Radar system A. I Backg
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Annex C ESM system C.1 Background A
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e communications, point to point, p
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(i-4 TACSAT Operations Phase The TA
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6-6 w J > a 3 v, [E ' 0 LL U3 I- Q
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(1-2 rcliabiliry pcrfornianccs, bot
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0 8-4 specific tools for each main
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0 0
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affichent un coot au kilo de 2 a 3
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I 1 - CONSTELLATION LAIJNCHES COST
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ls FIGURE 3 6-11
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a a
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SYmME DE NAVIGATION PAR SATELLIT'ES
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du sntcllitc fixCe. Aucunc controin
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0 0 ' ml 3200. 2800. 2400. 2000. 16
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A cct instant. ct si IC PDOP cat in
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giostationnaire (RS mlslnn contrc 5
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0 This pqxr is dividcd in lhrcc pat
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0 Grouad-air-ground communication T
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0 a .. . . .I AIR COMMAND AND CQNTR
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ENNEAAV ORDER OF BATLE ASSESSMENT D
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0 0 (CO") -COMMUNlCATlONTACSATSARE
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0 0 . 14-2 xiv)physical attack and
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14-4 There has been a minimum of jo
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Architecture TABLE -1 Number of Sat
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14-8 Table - 3 : The EHF Ground Seg
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0. 16-2 combincd analog and digital
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flgurm 2. Frequency Synlhmrlur Aduc
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L n , JA. " Flguro 5. LlghtwolgM LD
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GEOSYNCHRONOUSALTITUDEORBlT VARIABL
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I SYNCHRONIZATION TECHNIQUES FOR ME
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-U I 1 b I l l . . . . , Figure 2:
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@ & a time acquisition. Due to thc
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6 SYSIXM SYNCHRONIZATION ALGORITHM
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TACSAT payload. Sptinl and time syn
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\ I ..I , .. . . U' c L. rL 50 i !
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It is IqmmtQlive of the ,wc.sa Cmst
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I' !'.
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v / I ,p ,
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f I
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3. IAUWCUU SVSTEM SELECTION CRUQTXO
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19-41 5.8.1.8 A/Im faniity of whicl
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CURRLHT PRowcTKm N DEVELOPMENT " P
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.clrc;lih w m iua thc orhilot planc
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19-10 OcazO midm ~ r nof mp htb~rm
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19-12 0 'I% whicles must PW: lnunch
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8.3 Uniad KingdodWussia Inrtn'm HOT
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1P.16 'II-tcx chen@ngcnvimnmcntal c
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SPACECRAIT AND I.AIJNCII SIISlT.MS
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c Firvn 4. Horimld vrhiclr andpaylo
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H 8p~nwmd by DARPA ud will dcliwr8
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'ThcTauNt prylodckcoicwl inlnlactt
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20-10 (hcntercoaunnndma have ben di
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RESUME Puisque ks futun lanceun per
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. 232 CdcJ du IIIOIWYHI?~ Mmoeuvm m
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En rcvnnchc, m ce qui concemc la pe
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Lea masses d'ergoh pour les trois o
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- Figure 13 - Les orbiteo intermedi
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SVMMARy - rution inonly I5 monh. Qu
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I f igun 5-1 QulrUfar spcun@ syslrm
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?- I
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* Snull ground conlrol VMS 1s.a.a F
Page 305: .. 1. INTRODUCTION Attitude- and Or
Page 309: m, = f*U*d Whcn liquid bipropellant
Page 313 and 314: sensors, gyros) intorporated in the
Page 316: th: burn-our (or dry) mm and subsys
Page 322 and 323: 23-10 between the modulator output
Page 325: 23-12 . pcnsatc for thc imbact of l
Page 329: 23-14 e I w 11 n IS n n a 41 U 9s M
Page 332 and 333: 23-16 / Fig. 4.3.1: ICDS principle
Page 335: 23-18 Communication Weat her - Oper
Page 339: 23-20 r - .-_ -- - -. --_.._ I U i
Page 343: 23-22 I .a * .o.s 8.2 am3 c 0.012 a
Page 347: PRW mrms lottrfrsa : UDir Bnterfscc
Page 351 and 352: 24.2 CJ6Qh ion pl'b;pPelaion tho ap
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Page 357 and 358: [ Z ] C. Purrotta, M.Bieconi, A. Bi
Page 359 and 360: I 23-2 2. ):SADLISG TF.CIISOLOGY PR
Page 362: 124.1 PhwdAwmy Mimv.~tnhbkL.u#eApn(
Page 366: Lulrhd durimilr NASA md Navy p*bd o
Page 370 and 371: 2s-a The paylord concept is distinc
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Page 378: ~Y!!?w!L Tho fnasibllity of install
Page 382: c_- XZiiK matelT. mloy ka>r*can h.i
Page 386 and 387: , i'or a typical 708 operating duty
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Page 394 and 395: NovorthdanfS high frograonq CIQBfi~
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274 from soia may. For this mission
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=mitrioa~ ~ ~ h i frown ~ ~ e allei
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e The SAW must possess a raa)is$wet
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I I I ! 27-9 Different data rate: c
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In resent ears, industry made gr0fp
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I I I I I I , I .: I I I 27- 12 7.0
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27-14 , I I
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, ._ .'< . , '\ '
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LOW.oIlN ANTENNA b ClsLEWRIP 4 SOWR
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NOI-1-0' MZ-1-90 NO 3- I I 57 NO1-1
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Cost Efl'ectivc TacSats for Militar
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' Figure 3. Usa Driven Dwign Future
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L Figure 6. Tu&oprrpliom Rovi Usus
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Vlrtbl~ D~tect~n b Rows of 18um qua
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I I I . . / 0 - 0 0 0 0 0 0 0 0 0 0
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covering a variety of scenes, asses
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AbsltmsU 'E'AC.WT MEmOROWflCU PAYLO
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I I I I Trtarasiaiaand Pnogramme (M
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several chys. If S~CDPO term foreca
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e: l , / I Discussion Question: You
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7 t!lETTl?3T iDOCWMEWAmOT'd PAGE AG
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