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LA-UR--83-449

DE83 007561

TITLE: SPACE NUCLEARPOWERAND MAN’S EXTRATERRESTRIALCIVILIZATION

AIITHOR(S):Joseph J. Angelo and David Bud en &oTIum

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SuBMmTEDTo: Twentieth Space Congres~, Cocoa Beach, FL, April 26-28, 1983, MAsml

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TM rwporl WM pmpwod u -n ●?ouunl of work Ipmwod by an qoncy of tlw UrrltdStoIU (kmwmmorrt.Ndllwrho Unlld !iht- Oovwrnrrmm nor wry wrmy Ihararf, mx ●y of lhclr amployam, maha ●ny wsrramy, qffaM w Imphhofuwna snylopl IMW w Wa@ lrlllly fof the murscy, oanpktc-, or utofulrw of -ny lnformden, apporstuu produot, W prrrmua dlsokmod, or m~lm thmt 111 UM would ti Mrlnm pflvatdy ownd rlshl& Rdor. ma hordn to mry spaclflo commmlml pradual, procuk or Mwlca hy trade nmo, tridommk, mmnufaciuror, or MNrwlM doa no! nawosarlly uonnIIIuIs ur Imply III mlornrrwt, rowm. mandstbw, of hvorlng by h UnllodSIdm(bornmonloranywow thoratTIMVIOWI d ophrlom of mrthon emprawrl hmoln do nm rwoemmlly nma or roflool lb of tho Unlial !hta Uovornrrrwm or wry amncy [hwerrf,

OIarmDUIIIN dr IRISLIIL::M,ir::ml IJlll~ LosAlamos Na!lonalLaborator AlliallmmlmAlamos,New Mexico 8754i! mnutiouoni SPACE NUCLEAR POWER AND MAN’S EXTRATERRESTRIALCIVILIZATION

Dr. Joseph A. A,?gelo,Jr. Mr. David Buden Chafrman, space Technolofaypro9ram Program Manaaer Florida Institute of Techn~loqy Los Alamos National Laboratory Melbourne, FL 32901 Los Alamos, NM 87545

ABSTRACT space exploit~tion-.an era c~ara~t~rf~~(]by Operational flights of the SP?re Chuttle have routine manned nrrcss into cislunar snace. initiated an exciting new era cf s~ace ‘ltill- Humar te.hnlcal development at thp start nf zation and habitation. In f~ct, the s~art the n~xt millennium will be highlioht@d bv of the Third Millennium will be highlighted the creation of man’s extraterrestrialcivil- by the establishment of mafl’sex’:.rat@rres- ization, There are several foundational trfal cli,~lizatton, There jre three technl- tech,nlc~lsteps involved in the off-olanet c~l corn~rstones upon whick human expansion exp~nsirm of the human resource base. These into space will dePend: incluriothe development of reusable s~ace transportation systems; the estahllshment of 1) compact erQrgy sY;temS, es~ecially m?rmanen!ly manned space stations and hase$ power snd proDul!ion modul~s; (Initial’lyIn low-Earth-orbitand, eventllal- ly, throughout cislurtarspace); the develo~- ?) the abilit,yt,,rroct?ssextraterres- ment ~f space-baspd Industries; the creation trial materials anywhere in ht?llocf?n- of lunar bases and settlt?ments;and finally tric space; ant the utiliz,!tionof extraterrestrial r@- sources--as may be found on the Moon and the 3) the developmeflto: Permanent human Earth-aupro~chtnqApoollo/Amor astproids. habitats fn space. The Space Sh)ttlp represents the Unit@d Th? manned tnd unmaoned space missions of the States’ commitment to the first steo in thi$ ;uture will riemdnd ‘!irstkilowatt, then meqa- extrflterrestrlalRxpanslon process, sfnce watt, and !?v?ntliallyevt=nqiqawatt levels of operational So~ce Shuttle supoorts routlnp power. Enerqv, esp@clally nuclear enercJY, manned access to near-~arth SPRCP. TOIS will hIIIImost critical technical factor {n technical steo will he followed tsvthe cre#- th? developm,?ntof man’s extraterrestrial tton of p~rmanently manned space habitats.- clvili7atlon, first 10 low-Ea?th-orb{t(LEO) and thf?nin other advantageous reqfons cf cislunar Thts poper exmines leading space nucl~ar space, such al qmynchronous orbit, Al- power tcchnoloqv candidate:. Particular thouqh the early $D?c6!Stations in 10w- mphfl$is iS q{vrn the rneat.pipereactor tech- Earth-orbit would mo$t lfkelv d?pend nn nnlnqy currently under developmmt at th~ solar arrn.ysfor th?ir initial rzowersuP- Lot Alamos National Laboratory. This Rro- plies, nucle~r rrmtor~ could eventually h? qram i5 nlm~d at developing a 10-100 klh, incorporated ns such stations arow in si7P T-y?ar lifetime spdce nuclear pow~r plant. m-! cnmDltx\ty--as i’nr?x#mDle, tc sfitlsfv A$ the d~mand f’r spmo-bsscd powor reach~s incrcaspd Dow?r d~mfindsfor mht?rit,ls P~oc- m~qfiwattlev?l$, other nuclear t-e.sctor pss{ng, LfirqnsPace Dlatforms at af,n$vn- (iI~siqI,$inclljdinq: solid COW?, fluidi?rd cllronou$-Earth-csrhit(G[.0)could also bnti,eIIrl IJsfQouscore, ar~ considpled. offwltiv@lv us~ ouCl@l~rr?~ctors, In thi$ application, th~ rr!act?r$wollldnot onlv support thp inltl~l movwn~nt of mAqflvP pint. IN1N[IWI;I1ON.,..—- form~ from I.EOto IWO tilrouqhthe use of nljcl~arplpctric prnpulston svst~m< (NEFS)~ hlt wt~tlldal~o sQ*vP as t}}t,piatfnrm’s tzrim~ pnwor %nuf’ce oncp f)l)Pralir)nfil altituri~ 1<

1 achieved. ThuS, in the 1990s and beyond, citing new era of space exploitation. Ovar advanced-designnuclear reactors could rep- the next few decades, humanity will t?xDerl- resent a major energy source for br,thspace ence a subtle tr?chno-socialtransformation power and propulsion syltems. Some of the in which the phvsical conditions (e.q., hiqh sophisticated space missions of tomorrow vacuum, weightlessness), resoul-c~s(e.q., will require first kilnwatt and then mega- lunar a~d asteroid), and properties of outer watt levels of Power. This paper explores sPace (e.q., view of the Earth, biological man’s extraterrestrial civilization, and the isolation from Earth) are effectively used role energy, particularly nuclear, can Play to better the quality of life f,)rall on in the development of that civilization. Earth. This process has heen called the “humanizationof space.’’’l,5ttspart of this Drocess, man (only a selected few at THF w,JMANIZATIONOF SPACE first) will also learn to live in soaceo

Human proqress is bused upon challpnge and The humanfzatiun of soace is a comp’ex df!- corltinuedtechnical growth. As mankind velopment, which identifies the start of the enters the next millennium, expansion of the second phase of the Earth’s Planeta?v human resource base into space provides the civilization--expansionof the human pathway for continued material development. resource base into the Solar Svstem.lF6 In fact, the overall development of civili- The first phase of Dlanetary civilization zation in the future dePends on an over- tjeqanwith the Orlqlns of intell{a~nt life expanding outlook--an “open world” philos- on Earth and will culminate wit!)the full oPh.v.~S2*3 Its counterpart, a “ClOsed- use of the terrestrial resourc? base. The world” philosophy for human civil~zation, third, and perhaDs ultimate, ohase of Dlane- leads eventually to evolutionary stagna- tary civilization involve inlaratlon to th~ tion. As demonstrated by the law of natural stars. Figure 1 displays some of the ooten- selection, once a llfe form has become fully tial technical steDs that miqht occur durina adapted, It achieves an Intimate balance the second phase of the Earth’s cla\letar\’ with its environment. No further evolu- civilization.T,8 In this pro.iected tionary chanqes occur, unless the nature and sequence of technical achievements, mnn Chiiractprlsticsof the environment itself first learns how to Ile-manPntlvOCCUDV noar- change. Exploitation of space, the ultimate Earth sPace and tht?nex~ands throughout cls- frontier, however, provides mankind with an lunar space. As snace-baserlicdu$triali’o- infinite environment in whtch to continue to tion orows, a subtle out very significant develop and grow. transition point is reacheo, Man eventtiallv becomes fully self-sufficient in Cislunar Human civilization, forqed and molded in the space--that is, those human beinas livinu in crucible of challenqe and adverstty, must sPace habitats will no lonaer deDend on thp have new frontiers, both PhysiCal nnd Psy- Earth for the materials neces$~ry for their chological, In order to flourtsh.113 For survival. Th!ls,from that timr forward, without sufficient sttmul{, individuals as humanity will have two distinct cultural well as entire societies would eventually subs~ts: terran and nonterran or “pxtra- degenerate and experience an ever-decreasing terrestrial.” quality of life. Physical frontiers crovide the living spaces and new materials with rhe finai slaqc of this Lshas@of Dianetarv which to continue human progress. Psy- civilization will be hiqbliahted bv th? chological frontters SUPPIY the challenaet p?lmanen~occupancy of heliocentric or int@r- variety, adventure, and outlet for creative plane?ary space, Human settl?m?nts will aD- enerqies that make intelligent l~fe inter- pear 01 Mars, in the astcruid belt, and on esting. Unfortunately, this aoe is the selected moons of the cliantout@r DlanPts, first period in human history in which there FinalIv, as hurmnity--or at least i.% erntrx- are no new land or sea front!ers to he ex- tprrest,rial$u,>spt--st~rt$tfifill th~ I?co- plored and conquered on Earth. Only the ,Phere nf our native star with manmade space frontier with fts infinite potential “pl~n?,cids’’--ecosmic ‘mtierlust will also antiextent can provide the challenq@ and op- bP in nttract{na s?l?cted citi??ns of th? portunity necessary for continued, construc- So!ar System to the stars, With tho first tive development of the human race. In a iotwstellar misstons, the hum~n race will clospd-wfsrldcivilization--that is, one re- ind??d becor,ee qalactic ?x~lorer--cerhar)s str{ctfwito ju3t a sin~l~ olanct--no truly at thr?firei int?lliawst smi?s to sww$n nr.~Id@as, t?chnoloqles, or cultures can throuqh thm G~lau,yor perhan; destin~d to d~velop one? all planetary frontipr$ have nwet L’I’, ~tarfarinq Civilitfitlrml! br?encrossed; only valuations of old f4mil{ar themes can artte,

Thp r)l)~rationalSpace Trtln~portation Sy\tcm, Hurntsnrlevelopmwt nt thp start of th? Third or !llecoShuttle, has now {nltiatsuian ex- Ml)ls!nniumwtll be hi(lhl{qhtedhV the esteh-

2 ‘Iishmentof H extraterrestrialciviliza- nuclear reactions. These reactions in- tion. Three CT ical technical cornerstones clude: the spontaneous, yet predictable, that support th exciting development are decay of radioisotopes; the controlled fis- currently oercel d. These are: (1) the sion ~r sPlitting of h avv nticlei(such as &anium-235, symbol 2 U in a $Jstained ne[l- availability of c Ipact energy sourc~s for ~1 power and propulsion; (2) tne ability to tron chain reaction; nd the fusion or ioin- process materials ar~where in the Solar Sys- ing toqether of liqht nuclei2(such as deLJ- tem; and (3) the cre itionof permanent human terium and tritium, symbols 10 and 3T re- habitats in Outer sPlce.2$5 Spectively) in a controlled thermon11clPaP reaction, The thermal enerqy so liberated Energy--reliable, abundant and portable--is may then be used directly in space system a critical factor in developing and susta:n- processes cfemandinQlarqe quantities of inq man’s permanent presence in outer space. heat, or it may be converted oirectly intn Space nuclear power systems, in turn, repr@- electrical power. Until controlled thermo- sent a key enabling technoloqv that must be nuclear fusion is actually achieved, nuclear effectively incorporated in future space enerqv applications wi’11he based on radio- programs, if imaginative and ambitious space isotope decay or nuclear fission, applications and utilization progran are actually to occur in the next few decades.8 A qereric space nuclear power system iS de- For example, the movenv?ntof larqe quanti- picted in Fiqure 3. Here, the primarv sYs- ties of carqo from low-Earth-orbit (LEO) to tem output is electrical .?nerqy,which is hiqh-Earth-orbit (HEO) or lunar destina- .reated by converting radioi~~t,)n~decav tions, the operation of very larclespace heat or the thermal enerqy ;~leased in nuc- platforms throughout cislunar space, ant the lear fisrion into electrical enerqy, uslnq start-up and successful operation of lunar static conversion (e.q., ttw?rmoelectricsand bases and settlements can all benefit from thermionics) or dynamic conversion (e,o,, the creative appl~cation of advanced space the Rankine, Bray+on, or Stirlina thermo- nuclear power technology. Very imaginative dynamic cycles) principles, Contemoorarv future space activities, such as asteroid options for nuclear en~pqy heat sourcps and movement ard mining, plant!taryengineering companion power-conversion suh$ystems arp and climatf control, and human visitations shown in Fiqure 4. While these ootion$ are, to Mars and the celestial bodies beyond, of course, f,.;all inclusive, thev nevPrth~- cannot even begin to be crediblv considered less form the basis for intelligent olannina without the availability of comp~ct, pulsed of nuclear-power sources apoiication for and steady-ttate, enerqy supDlies in the soace missions in the next decade and ht?- meqawatt and, cventualiy, qignwatt regime. yand. Rpdioisotooe and nuclesr rp’ctor Dower systems--up to a few hundrefikilowatt$ Since the beq{nninq of the Space Age in the elpctric--are fbrther classified {n mptrix late 1950s, a range of nuclear power suDPIY format in Fiqure 5, For sDace-oower aoDli- ootions hns been rteveloDedby the United catims in th? mmawatt reqime and tzevonri, States to support civilian and military there are a number of oossibl? advanced nuc- space activities. Tomorrow’s space ProQram, lear rf!actc technology options, These keyed more heavily pernaps to applications desiqns includp the solid-core nuclear and exploitation objectives, wI1l require reactor (a derivative of thp Rov~r orocr~m even ltr~er quantities of relioble, lonq- nuclear rnckpt technoloqv), tho fluidird lived power, Nuclear enerq,yjudiciously ao- bed reactor, ~nd the qaseous core nuclenr pli?d in future space mission’ offers sever- reactor. al distinctive advantages over trafiftional solar and chemical space-Dower systems. These advantages incliJde: Coimact size, US SpACE NUCLEAR PROGRAM Iight-to-mod?r?tt?mass, lonq-oporatinq life- tffno$,operation in host~lf!environments since 1961, the Unit@d StatPs h~! l’!llnchw! (e,qt, tral)pedradiation belts, surface of over i?ONASA and militarv SPisct=systems that Mars, moons of outer planets, etc.,.), opcra- derived all or nt lea$t rsartof th?it’Dower tlon i!ldep?ndpntof tlw sy$tr!m’sdistance requirements from nuclear enerqy snurcP~,, fr[,mnr )rientotion to the Sun, and in- Thole svst.omsAnd missinns arp summari?~{iin crpa MI s ce system reliability and auton- Tnhle 1, Af can b~ swn in this tablp, tll ~my,3,i0,~f !n fhct, 4. power requirements but Onp Of the Drf!viousmi$sion$ IJ$Pdrdriio- approoch thf!h~Jndred$of kllnwatt$ and mcqa- i$otop~ th~rvnnploctricrronpratorj RTGs) wfittoloctric reqim~, nuclear ~nerqy appchrs f~lplrdbv Plutnnium-?3R (symbnl Pu). ThP to be the only realistic space Dowrr suPIJl,Y SNAP-1OA \v*,t@mwat a cmnp~rt nlw# tsrI~~#r- oPtlon. (SW Fiqure i!). tor th8t us?d fully pnrlcllwllJranillm-?358$ thp fupl, Th? acrnnym “SNIP” stan(i~for “~,$tmns for NIJcl@arAuxilihrv Pnwmr,” O(id mmhrrf dpslqoacc rari7’oi\otnnO~vst~m~,

3 while even number designate nuclear reactor converter. The lithium then condenses, and systems. is returned to the eva~orator end of thi? heat pioe by the capillary action of the From the very beginninq of the US sPa~e nuc- wick. No ciumnsor compr~ssors are us~d for lear power program, great emphasis has been heat transport. The fins around the heat plar.,.don safety. Contemporary sIolicyal,d pipes enhance heat transfer from the U02 practices for all space nuclear power fuel to the heat oiDes, redllCinathe tenl- sources promote designs that ensure that the peratures in the U02, Surrounding the levels of radioactivity and the probability core i$ a containment barrel, wbicfiorovidps of nuclear fuel release will not provide a~y supDort to the fuel modules, but is not a significant risk to the Earth’s Population pressure vessel. The container also pro- or to the terrestrial environment. For vides a noncomPre$sive suooort for the radioisotope heat sources, this aerospace m~ltifoil insulation. Multiple reflective nuclear safety policy essentially consists insulation layers reduce the core heat 10SC of providing containment that is not Preju- to an acceptable level. The reflector sur- diced under any circumstances, includinq rounds the core and reflects neutrons hack launch accidents, re-entry ur impact on land into the fueled reqion. located w+thin the or water. For nuclear reactors, the safety reflector are drums that a~~ rotated by mechanism consists of maintaining sub- electromechanicalactuators, On oart of criticality under all conditions, normal and these drums is a rieutron-absorDtfonmate- otherwise, in the Earth’s atmosphere or on rial; the Positfons of thfs material are the Earth’s surface. After the reactor has used to establish the reactor oower level, experienced power operation In space, the reactor will be prevented from re-entering Power conversion tn the SP-100 system is by the terrestrial biosphere. This is achieved the direct thermoelectric conversion of heat by ensuring that the reactor achieves a to electricity. Thermal enerqy fs raclfaterl final orbit that has a sufficient lifetime from the heat pipes to oanels contairilnq to permtt the decay of fission products and thermoelectric mater;al. Hot-shoe thermal other radioactive materials to levels that collectors concentrate the radiant enerov no longer represent a radiological risk. from the core heat pipes. The heat Is con- orbital lifetimes In excess of 300 years ducted throuqh the thermoelectric material, support this ~erospace nuclear safety producinq electrical enerqy. Insulation is b,ilosophy. used around the thermoelectric material to reduce the thermal losses, Heat that is not A typical space nuclear reactor power plant, used f.s radiated from the outs~de surface to such a$ pictured in figure 6 consists of a sPac@; this is the cold shoe comoonent of nuclear reactor as a heat soupce, a radia- the thermoelectric elements, Bv di$trlhut- tton attenuation shield to Drotect the PaY- inq the thermoelectric elements over a wide ?oad, the electric power conversion equici- area with a sufficient number of elements, ment, and a heat rejection system to the cold shoe becom?s the !wat rejectton eliminate waste heat, radiator, Table 11 gives ‘.~echaracteris- tics of a 100-kWe power plant. The oower Fiqure 7 roughly classifies tne leading olant welqhs ?625 &q if imo~oved siltcon- technology candidates based on reactor type, qermafnium thermoelectricmaterials are conversion system, ard heat-rejection used, and less than 2000 kq wfth carhirleor sys’.m. Heat-pipe reactor technology iS sulfidf?materla?s, The overall ?encithis currently unfierdevelopment in the $P-1OO 8.5 m for the earner s,vstem. proqram, This program has a qoal of de- ~eloplng a 10-100 kkle,7-year-lifotimr AS depfcted in Ftqure 7, thermoel?ctr~c con- Iluclear:eactor power Dlent, This same verters are Iimit’d to th~ power-oroductlon re~ctor technology can be used for thermal reqion below 700 kWc because of the num$err power levels of 10-40MW, of smai? modules involved and thefr low ef- ficiency, From 200 kh% to thp meaawatt The reactor pictur~d in Fiqure 8 has a level, a chotce of conver’:rs is oossthle cpntr~lly fueled core reqfon made UP of 120 between Rankin*, Brayton, and Stirlinq fuel modules, Thes@ modules consist of a CYCIPS, which would not requtre any tncreo$~ bent pipe with circumferential fins attached in reactor temperatures, Thermionic con- findfuel wafers arranged in l~yers betwe~n verters are another possibility, but would the ftns, The heat pipes are hsed to trans- rqauire reactor tpmperet(lres sevcr~l hljndrefj r)ortthe reactor thermal ene’qy to electric doqrces Kelvln hi~h?r. Hiqher temopratllr? pow~r convertw’s, ancicon$ist of acylindrf- reactors incr?~se fuel swellillqand material cal tlJbc,llnod w)th a metal screen wick, Problems, Converter efficiencies of 15 to Lithium, the working flu!d, {~ @vanorated in 30% firepossib;?, but the hiqher efficim- the rnactor-f~icl-mori~llo$@ctton of tlw heat ctes lead to Iowpr befitrpjectfon temD@~a- piue, Th@ v~,mr tr~vols up the heat lliPe tures, R?cfiu$ehp~t radiated to snacp unt{l ttw I\Cat{S qtvon UP t40the elcctrtcal

4 follows a f urth-power relationship in tem- than z few thousand deqrees Kelvin, the ao- perature (T8), high reject temperatures Drcoriate nuclear fuel WWJIC!be uranium tend to have much reduced radiat~r areas, hexafluoride, UF~, Above abnut 5000 K, As power levels increase, higher heat rejec- uranium metal would be vaporized and ionized tion temperatures usually dominate the with the fuel as a fissioning olasma, At choice of converters. Although work has lower temperatures it is desirable, and at been performed on all these converters In hiQher tcmoeratures it is nece$sary to keeD the past, activity on space systems is no the qaseous fuel seDarate from th~ cav!tv longer onqoinq. There arzpearto be no tech- wails. This is accomplished throllqhfluid nology barriers to Power Plants UP to a few dynamics by usinq a higher velocity buffer megawatts, but active development is needed qas alonq the wall. Power is extracted bv if any of the power options above a few hun- convection or optical radiation, dmendino dred kilowatts are to be available to space on temperature. Gaseous core reactnrs offer mission planners of the 1990s, simple core structures and certain saf?tv and maintainability advantages, The basic As the Dower-1evel demand FXPafldS to the research development was comDleteriDri,)rto tens-of-megawatt levels, solid core, f}uid- proqram termination, ircludinq the tiemon- ized bed, or even gaseous core reactors stration of fluid mechanical vortex confine- might be considered. For space, solid-core ment of UF~ at d~nsities sufficient to reactors were most extensively develooed as susta+n nuclear criticality. part of the nuclear rocket proqram, The Rover design featured a graphite-moderated, h drogen-cooled core (Figure 9). The 93.15% SPACE INDU~TRIALIZATION 2~5LIfuel was in the form of uC2 parti- cles, co?ted with a oyrolytic graPhite. The Sapce industrializationmav De defind as a fuel was arranged in hexagonal-shaPed fuel new wave in man’s technical development in elements, coated with ZrC; each element had which the sDecial environmental condition$ 19 coolant channels, The fuel elements were and Properties of outer sDace are harnessd supported by a tie-tube structural suPPort for the economic and social benefit of system, which transmitted cnre axial Pres- peo$le on Earth. Some intfrestinq Proper- sure load from the hot end o+ the fuel ele- ties of SDaCe inciude; hard vacuum, weiqht. mentc to the core inlet support plate. Sur- lessness or “zero-qravitv”effects, low rounding the core was a neutron refle~tive vibratfon levels, a wld~-anctleview of Eartli barrel of beryllium, with 12 reactivity con- and tbe Universe, and coriolet~isnlation trol drums containing a neutron-absorbinq from the terrestrial biosDhere,5,1~*l~ material. The reactor Has enclosed in an aluminlJmpressure vessel. Electric power UP Recent aerrispacestudies12$13 have at- to 100MW cou]d be generated by replacing tempted to look some flftv wars into the the rocket tfirustnozzle with power conver- f(Jturcand to correlate anticipated human sion equipment. fhis is a limited-life SYS- net?dswith qrowinq space Opportunities. tem, howeker, A low-pnwer electric, loncj- ThPse space inciustrip,lopportunities can he life mode could be achiev~d by exracting conv@nlently divided into foul basic cate- enerqy through the tie-tube suPPort sYstem. gories: (1) lnformetlon servtces, (?) Dro- The Rover technology is ready for flight cle- ducts, (3) enerqv, and (4) human ec!iviti~~, velopment, havinq been tested fn some 20 re- (StleFigure 11.) actors. Pea’:perform~nces sre shown in Table III. In the full-scale exploitation of cislunar space nuclea~ el(!ctricpropulsion svstem$ High-power requirements miqht also be IIIf?L by (NEPSI will serve a crit;cal enablinq role fluidl?ed bed reactors, in either the rotfit- in the efficient transport af massive, non- inq or fixed-bed forms. The former was in- priority carqoes throua$out cislunar space, vestigated as a rocket Propulsion concePt, In manv m{sslon’;,the NEPS w{ll serve not and the latter has been propo~.edfor space only as th~ Prooulsiw?mefi~sof placinq q electrical powpr, A modest research @ffol’t mas~ive Dt,y!narlin an aoornoriate orwratino in fluidlzed bed reactors was carried out orhlt, but once the operational location is from 1960 until 1973. rp~chpd, the nuclp~r reactcr would then service at the prfme oower SUDDIY for mfinv Another candidate for mcqawatt-Power re- yvars of cantinuo~ls,r)rnfit-makinqoDPra- actors i, a gaseous rore reactor systcm. t!on of th~ payloq$. NucleI\relectric The centra! component of such a gaseous core propulsion $,y$temscould also b~ us~rlas re- reactor {s a C!vity wh~re the cuclear fuel usable orfittnltrrtn%fervphicles (OTVS) or is in the qoseou$ slate. The rf?hctorcon- “51)8PPtuq<,” lhes~ nrorsuls{veworkhorses cvpt shown schomoticolly In Fiqure 10 is fin of tmnnrrow wnllldqently l{ft mfissivecar- externally rnoderateiicavtty a$semtJIYthat qovsl sunolie$ mnd mater{als, Iarcm find c(lntain$tt,puranium fuel in the q~seous frfiqilepfiyloadsthei hsrthpl~na$$ombl~d in ~hAsP, For twmraturc rcquirmcnts lefs low-Earth-orbit,or ev(ll pnt?re (ljnocr(j~ipd)

5 habitats, and ferry these cargoes to their from hundreds of kilowatts (electric) to final destinations in Cislunar spce. Return several meqawatts. voyages from lunar or geosynchronous orbit would witness these same nuclear electric vehicles carrying space-manufactured or THE MOON-KEY TO CISLUNAR SPACE selenian prod~cts back to the terrestrial markets, finally, the continued, more Thp bio~rl jS Earth’s onlv natural satellite sophisticated scientific exploration of the and closest celestial neighbor. Relative to Solar System will also require nuclear elec- its primary, it is extremely larue. In tric propulsion systems as ambitiouc, ad- fact, the Earth-Moon system miqht be re- vanced exploration missions are undertaken qarded as a “double planet” system. N~t too to both the inner planets and the outer long ago, the Moon was only an inaccessible planets. celestial object--but todav, throuqh t$e technology of the Space Age, it has bwome a In a real sense, the information service “planet” to explore, exploit, and area of space industrialization already inhabit.14 exists. Space platforms are now p~ovidinq valuable communication, navigation, meteoro- ‘Toinitiate the further exploration of the logical and environmental services to Deople Moon, we can first send sophisticated around the globe. Further exoansion of such machines in place of men. For examDle, an services involves more massive platforms in unmanned lunar orbiter could circle the Moon orbit and much higher power levels. For ex- from pole-to-pole remotely measurinq its ample c rrent aerospace industry evalua- chemical composition, qrav+ty, maqnetisfn, tionsIY23 3 indicate that qreatly expanded and rad’ioactlvity. T?is Lunar Polar Orbiter information transmission services from space mission would concinue t$e scientific tasks represent some of the most beneficial in- started bv the APO11O ProQram and would pro- dustrialization activities that could be ac- duce extensive maDs of the entire lunar sur- complished in the next decade or so. A face, Automated lunar surface rovers would multifunction information services Dlatforr,, bp used to make detailed lunar surface sur- of the ma~or capability is needed at Qeo- veys, determining Dhysical and chemical synchronous-Earth-flrbit.A ba~eline GEO characteristics as well as searchinq for platform would require ome 550 kilowatts potential mine!’alresources. These auto- (electric) ofpower.8,1~ Tbisunmanned powered by radioisotoo~s (most platform would provide five new natioliwirle !%l%b~$v~ ~k) will beor)erated near the information service>: (1) direct-broadcast poles, on !he far side of the Moon and in TV (five nationwide channels, 16 hours per other interesting hut previously unvisited day); (2) pocket telephones (45,00rlprivate lunar regims. Then, when man himself ch~nnels linked to the current tel@hone retllrnsto the Moon, it will not be for a system); (3) national information services brief moment of scientific inquirv as oc- (usinq Pocket telephone hardware); (4) curred in the APO11O Proqram, but rather as electronic teleconferencing (150 two-way a Permanent inhabitant--buildina bases from video, voice and facsimile channels); and which to explort?the luna~ surface, estab- (5) electronic mall (40 million vaqes trans- lishing science and technoloq,vlahor~tories. ferred Overniqht amgng 800 sortillqcenter ,) and exDloitinq the lunar resource base in support of humanitv’s extraterrestrialcivi- Another space industrializationopportunity lization. involves a Sgace Processing Facility in near-Earth-orbit. De;iqned m inly for zone Table IV suqqests several .taqes of lunar reftning ~nd crystal qrowth,l! this development and companion uclear power re- facility has fifteen furnaces capable of ~~:rements. It is anticipated that the producinq 750 boules of finished pruduct st staqe will involve site Preparation every 60 days. The Space Shuttle would prior to the establishment of the perrna- service raw material maga~ines and return nentl,yinhahitecllunar has?. Robotic sur- finished “space-manufactured”products to fac~ eqljipmentcontrolled by orbit;na soace markets on Earth, The conceptual facility craft wculd Drepfirea suitable luna~ site would be capable of Producinq 4500 bo’~les for a permanently inhehited base of opera- (wrighing some 21,000 kilograrits)of fintsh- tions, One ot the areas t)reDaredwould be ed products annually. A continuous power the site for the nuclear Power reactors ?evel of 300 kilowatts with a peak power re- needed in Staqe i?of lunar development. quirement of somp 550 kilowatts is projected. These remotely controlled robotic devices w, ld be powered by radioi$otoues (DrObablV Gl~osynchronous.Earth-orbitis also the .?~~pu)enahlinQ continuous operation favored locat~on for a number of other Eart},- throughout the flJlllunar dtv night cVCle oriented applications and scientific plat- (some 28earthd6ys). RadioisotoD@ thermal- f~rms ..l)~th mannptj and unmanned, Power re- electric qcnerators (RTG), like the GPHS-RTG quircmcnt$ for Lhese systems would ranqe W!th a sp~cific power 5/3 Wkg, have Proven

I to be rugged, highl.Yreliable, and capable F,nally, as the lunar settlement expands and of operating in hostile environments for grows economically, a point will be reached years at hundreds of watts levels of power. when the lunar civilization, for all practi- With the creative use of dynamic Power- cal purposes, becomes autonomous of Earth, ccnversion equipment, as, for example, an o- Lunar products would be widely used through- rganic rankine cycle, the GPHS could also be out cislunar soace--the lunar economy, beinq capable of supPlying kilowatts of power in driven by the abundance of nuclear electric support of lunar-developmentactivities. power, makina full lunar-cycle productivity a technical and economic reality. As part The initial permanently manned lunar base is of the full self-sufficiencyexperience in projected to have a habitat for 6-12 per- Stage 5, a lunar nuclear fuel cycle will sons. To meet their power needs, a 100-kW also evolve, takinq advantaqe of native e“lectric“jclear re~ctors (of the SP-1OO Uranium and Thorium minerals, as well as the heat pipe and core design) would support the classic breedinq reactions involvinq fertile initial lunar base (see Fiqure 11). By the 232Th and 238u, time man returns to the moon as a permanent inhabitant,these nuclear reactor units will have a well-established engineering ~erfo-- SUMMARY mance on unmann ‘ spacecraft and manned space-station operations throuqnout cislunar If man is to exoand beyond his terrestrial space. Of course, minor modifications of womb and assume his proper role in the cos- the bas:c reactor system will be needed to mic scheme of thinqs, he must have abundant, suop~rt n~nned lunar activities. For ex- compact, and reliable enerqy supolies to ac- ample, a 4 radiation shield could easily company him on his journey beyond the Earth’s be implemented using lunar soil material. atmosphere. Nuclear enercty,DrOperlV de- veloped ana used, is the sini qua non for The initial lunar base, focusing on detailed manned extraterrestrialcivilization. exploration in resource identification,will then evolve into a multihundred-person early settlement, One of the main objectives of this early settlement wI1l be to conduct basic research and development, which takes advantage of the lunar environment. Another key objective will be the engineering demon- stration of prototype processes upon which a viable lunar economy might eventually be based, Expanded versions of the SP-1OO heat- pipe r.actor, coupled to more efficient power-conversionsystems such as Brayton, Stlrlinq, or Rankine cycles, would provide wgawatt le~els af el~ctric power to the early ldnar settlement,

In Stage 4, the early lunar settlement matures and economically exploits Processes developled tn Stage 3. Lunar products feed the the growth of lunar expansion, fi!~ds markets throughout clslunar space, and may even export products to selected terrestr~al markets. Power levels on the order of a few hundred megawatts electrfc would be needed to support the processi,igof lUnar tIIaterialS and the operation of advanced transportation systems (such as surface electrtc monorails and mass-driver systems). An ad’’ancedde- sign nuclear reactor system Is envisioned w]th 30 year or more useful lifetime, on- llne refueling, a[id rnbottc malnta{nabtlitv featurrs. Another characteristic of this new grmcration of lunar nuclear reactors would he “walk-away safety’’--that1s, if ti rnolfuoctlon;hould occur In any part of t~e Power Plant, it ts so dcstgned that no operatur action or even mochanfcal automatic control mechanism is needed to achieve a safe condition,

7 l-ABLE I

SUMMARY OF SPACE NUCLEAR POWER SYSTEMS LAUNCHECIBY THE U.S.A. (1961-1982)

POWER MISSION TYPE ——SOURCE SpflCECRAFT ~AUNCti PATE STATUS

SNAP-3A TRANSIT 4A NAVIGATIONAL JUNE 29, 1961 SUCCESSFULLY ACHIEVEO ORBIT SNAP-3A TRANSIT 4i3 NAVIGATIONAL NOVEFIBEI? 15, 1961 SUCCESSFULLY ACHIEVED ORBIT SNAP-9A TRAh!sIT-5BN-l NAVIGATIONAL SEPTEMBEIl 28, 1963 SUCCESSFULLY ACHIEVED ORBII SNAP-9A TRANSIT-5BN-2 NAVIGATIONAL DECEMBER 5, 1963 SUCCESSFULLY ACHIEVEC ORBIT SNAP-9A TRANSIT-5BN-3 NAVIGATIONAL APRIL 21, 1964 MISSION A60RTEO: BURNED UP ON REENTRY SNAP-1OA (REACTOR) SNAPSHOT EXPERIMENTAL AP~lL 3, 1965 SUCCESSFULLY ACHIEVES ORBIT SNAP-19B2 NIMBUS-B-1 METEOROLOGICAL MAY 18, 1968 MISSION ABORTED: HEAT SOURCE RETRIEVED SNAP-1963 NIMBUS 111 W4~ROLOGICAL APRIL ’14,1969 SUCCESSFULLY ACHIEVED ORBIT SNAP-27 APOLLO 12 NOVEMBER 14, 1969 SUCCESSFULLY PLACED ON LUNAR SURFACE SNAP-27 APOLLO 13 LUNAR APRIL 11, 1970 MISSION ABORTEG ON WAY TO MOON. HEAT SOURCE RETURNED TO SOUTH PACIFIC f_;EAN. SNAP-27 APOLLO 14 LUNAR JANUS.RY31, 1971 SUCCESSFULLY PLACED ON LUNAR SURFACE SNAP-27 APOLL() 15 LU’4AR JULY 26, 1971 SUCCESSFULLY PLACED ON LUNAR SURFACE SNAP-19 PIONEER 10 PLANETARY MARCH 2, 1972 SUCCESSFULLY OPERATEO TO JUPITER AND BEYONLl SNAP-27 APOLLO 16 LUNAR APRIL 16, 1972 SUCCESSFULLY PLACEO ON LUNAR SURFACE TtlANSIT- “TRANSIT” NAVIGATIONAL SEPTEMBER 2, 1972 SUCCESSFULLY ACHIEVED ORBIT RTG m-rp:-ylx) SNAP-27 LUNAR OECEMBER 7, 1972 SUCCESSFULLY PLACEO ON LUNAR SURFACE ~NAP-19 PIONEER 11 PLANET/YrlY APRrL5, 1973 SLXC~SS~LILLY OPERATED TO JUPITER, SATURN, AND BEYON2 SNAP-19 VIKING 1 MARS AUGUST 20, 1975 SU(tESSFULLY LANDED ON MARS SNAP-19 VIKING 2 MARS SEPTEMBER 9, 1975 SUCCESSFULLY LANDEO ON MARS MH14 LES 8/9 COMMUiiiCATIONS MARCH 14, 1976 SUCCESSFULLY ACHIEVED ORBIT MHM VOYAGER 2 PLANE”[ARY AUGUST 20, 1977 SUCCESSFULLY OPERATED TO JUPITER AND SATURN tfltiw VOYAGER 1 PLANETARY SEPTEPl13EFt5, 1977 SUCCESSFULLY OPERATED TO JUPITER AND SATURN TABLE II

SP-1OO PERFORMANCE AND MASS SUMMARY

Late 1980s —.—— .— Output Power (kWe) Range 10- 100 10- 100 Nominal 100 100 Reactor- Thermal power (kWt) Range 200 - 1600 Reference Eesign 1480 950 Design Life (yr) Design Poher Total 1; 1; Overall Dimensions Length (m] 8.5 7.0 Diameter (max)(m) 4.3 4.3 Radiator area (m$) 70 43 System itass (at Reference Design) Reactor 405 370 Shield 790 670 Heat Pipt?s 450 215 TE Conversion 375 155 Thermal Insu’;ation (including ?nd panels) 285 195 Radiator 80 35 Structure (10%) .— 240 165

Total System Mass 2625 1805 Specific Power (W/kg) 38 55 TABLE 111

REAC”rOR SYSTEMS TESTS PERFORMANCE

KIWI-4BE I NRX-A6 Phoebus-?A Pewee-1

Reactor Power (Md) 950 1167 4080 507

Flow Rate (kg/s) 31.8 32.7 119.2 18.6

Fuel Exit Average 2230 ?472 2283 2556 Temperature (to

Chamber Temperature (K) 198U 2342 2256 1837

Chamber Pressure (MPa) 3.49 4.13 3.83 4.28

Core Inlet Temperature (K 104 128 137 128

Core Inlet Pressure (MPa) 4.02 4.96 4.73 5.56

Reflector Inlet Temp- 72 84 68 79 erature (K)

Reflector Inlet Pres- 4.32 5.19 5.35 5.79 sure (MPa)

Periphery and Struc- 2.0 2.3 6.48 tural Flow (kg/s) --L TABLE IV

STAGES OF LUNAR DEVELOPMENT AND POWER REQUIREMENTS (1992-?092)

Probable Nuclear 5W!2 Activity Power Level Power Supply -

1 Automated Site Pr~paration few KWe Radioisotopes (RTGs)

2 Initial Lunar Base -100 kWe Nuclear Reactor (6-!2 persons) (SP-1OO)

3 Early Lunar Settlements -1 Mb!e Expanded SP-1OO (103-104 persons) (Advanced Design)

4 Mature Lunar Settlement -100 MWe Nuclear Reactor (102-104 persons) (Advance Design)

5 Autonomous Lunar Hundreds of Nuclear Reactors Civilization (Self- Megawatts (Advance Design, Sufficient Lunar Electric Complete Lunar Economy: >105 persons) Nuclear Fuel Cycle STEP 1: Permanent Occupancy of Near-Earth Space

o Space Station/Space Operations Center [6-12 persons] o Space Base [50-200 per;ons] o Orbiting Propellant and Service Depot o Near-Earth Orbital Launch Facility

STEP 2: Permanent Occupancy of Cislunar Space

o Ldrge Power Plants (nuclear) at GEO [megawatt rangej o Manned Space Platform at GEO [6-12 persons] o Orbiting Lunar Station [6-12 persons] o initial Lunar dase [6-12 persons] o Cislunar Orbital Transfer Vehicles o Permanent Lunar Settlements [200-30/1 persons]

STEP 3: Full Self-Sufficiency in Cislunar Space

o Sp~ce Connnunitles in Earth Orbit o Space Cities [e.g. Krafft Ehricke’s “Astropolis”J & o Extensive Lunar Settlements o Settlements Throughout Cislunar Space o Utilization of the Apollo/Amor Asteroids

STEP 4: Permanent OccupUncy of Heliocentric Space

o Mars Orbiting Station o Initial Martian Base o Permanent Martian Settlements o Asteroid Belt Exploration o Mimed Bases In Asteroid Belt o Bases on Selected Outer Planet Moons [e.g., Titan, Ganymede] o Planetary Engineering Programs [e.g., climate modification] o Manmade “Planetoids” in Heliocentric Space o First Interstellar Missions

Figure 1. POTENTIAL STEPS IN PHASE TWO OF THE tANrH’S PLANEIARY CIVILIZATION .— -

REGIMES OF POSSIBLE SPACE POWER APPLlcABaL13”v

I(F

. I(P .

101 IA

10° WV

10-1

1-2 :ARS 1 DIJR.4TION OF USE GENERK SIPA= ~UCLEAR POWER SYSTEM

REJECTED THERMAL ENERGY b PRODUCTS OF /“’ NUCLEAR PROCESSES

THERMAL L ENERGY THERMAL ENERGY-TO- ELECTRICAL NUCLEAR ENERGY k ELECTRICAL ENERGY HEAT SOURCE > ENERGY CUTPLm CONVERSION

DIRECT THERMAL ENERGY UTILIZATION FOR HEATING, COOLING OR IN HIGH THRUST PROPULSION SYSTEMS

Figure 3 -.

OPTIONS COVERED IN SPACE MUCLEAR PROGRAM

●

RA~lOISOTO~E FUELED

(=P@2)

HEAT SOURCE [ ‘“a REACTOR (235~)

Therrnoelectrics

TherrnionicConverter

POWER CONVEFISION 6rayton Cycle Turbine/G_~r

Organic Rankine Cycle Turbine/G~ator ~DyNAM’ce StirlingCyCle/Ge*ralOr

Figure 4 CLASSIFICATION OF NUCLEAR POWER SYSTEM TYPES BEING CONSIDERED FOR SPACE APPLICATION

—. ELECTRIC POWER RANGE lflUCLEAR POWER SYSTEM TYPE (MODULE SIZE) POWER CONVERSION

RADIOISOTOPE THERMOELECTRIC Up to 200 We STATIC: THERMOELECTRIC GENERATOR (RTG)

RADIOISOI OPE DYNAMIC 0.5 kWe – 2 kWe DYNAMIC; 8RAYTON OR CONVERSION GENERATOR ORGANIC RANKINE CYCLES

REACTOR SYSTEMS 10 kWe – 100 kWe STATIC: THERMOELECTRIC (HEAT POE)

REACTOR SYSTEM 1 – 10 MWe BRAYTON CYCLE HEAT PIPE RANKINE CYCLE SOLID CORE STIRLING CYCLE

REACTOR BRAYTON CYCLE 10 – 100 MWe SOLID CORE (OPEN LOOPj FLUIDIZED BED STIRLING GASEOUS CORE MHD

Figure 5 SHIELD

HEAT PIPES

THERMOELECTRIC PANELS

SP-I 00 NUCLEAR POWER SYSTEM RADIATIVELY COUPLED SYSTEM DESIGN

Figure 6 a CONVENTIONAL h! 1 - *LKNJID DROPLET, BELT a k THERMOELECTRICS THERMIONICS THERM IONICS E BRAY TON RANKINE BRAYTON > RANKINE STIRLING RANKINE STIRLING $ STIRLING v f /m

‘ 5+ HEAT PIPE z U ~ x-iii?! K

4 0 10-2 10-’ 10’ 102 F%UER (hiWe)

Figure 7. Leading Technology Candidates HEAT PIPE SFWICEREACTOR

./?r-w\ .— . .

HEAT PIIW lUO-*lLi)

FUEL LAYERS Y ‘“”’’-%)>

. “EFLECT”R’’)*!SAFETY PLUG CAP (M) ~ T~AL ltiSU.ATti t~T1-F”M)

Figure 8 REACTOR DESIGN FEATURES

Epl.THE~~AL, ~RAJl+[~c#~ERATED, HYDROGEN-CWLED REACTOR

!!‘r#”’ELD USED ENRICHED 93.15% URANIUM-= CORE SUPKMT AS FUEL PLATE F(3RWARD TIE ill POWER FIAITENING BY VARYING FUEL mm LOADING AND FL~ DISTRIBUTION

CORE INLET ORIFICES CONTROL FLOW C.ATERAL DISTRIBUTION SUWWRT SPRING CORE SUPPORTED BY COLD fNO :U~RT SEAL PLATE AND STRUCTURAL TUBE ARRANGEM- SEGUENT ENT

REACTIVITY CONTROL BY ROTATING DRUMS IN REFLECTOR CONTAINING NEUTRON ABSORBER

AFT END SWPORT Rlffi

Fiaure 9. Nuclear Rocket Reactor d—–- Design Features URANIUM FEED

PINS,

PLASMA-’-J Al 1 v- ...... 111 ~- ...-..”... -..-.-.”. ‘j.)1VjJ I I [N DRIVER ‘ ‘ ‘$$!cc:”’.+..IL /’IN FUEL COOLANT xii \i\ \ CAVITY WALL PR c

LLANT 4-N

Figure 10. Gaseous Core Reactor Concept

. o 1NFORMATION SERVICES

- Information Transmission [education, medical aid, electronic mail, news services, teleconferences, telemonitoring ard teleo~eration, time, navigation, search and rescues ...1

- Data Acquisition [Earth resources, crop and forest management, water resources, weather and climate, ocean resources, mineral resources, environmental monitoring, land use surveys, ...]

o PRODUC”rS

- Organic [biochemicels: isozymes, urokinase, ...1

- Inorganic [large single crystals, high-strength fibers, perfect glasses, new alloys, high-strength magnets, ...]

o ENERGY

- Power From Space [nuclear or solar]

- Nuclear Fusion Research in Space

- Illumination from Space

O HUMAN ACTIVITIES

- Medical and Genetic Research

- Orbiting Scientific Laboratories

- Space-Based Education [i.e., “The University of Space”]

- Space Therapeutics [e.g., “zero-gravity” hospital, sanitarium ...]

- Space Tourism

- Entertainment and the Arts

Figure 11. MAJOR AREAS OF SPACE INDUSTRIALIZATION . lx

aJ L .Si L

, .