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be　clever　about　reducing　costs　and　making　true　international　partnerships；　the　justifications　bee　more　pelling。

Until　a　national　debate　on　this　topic　has　transpired；　until　we　have　a　better　idea　of　the　rationale　and　the　cost/benefit　ratio　of　human　missions　to　Mars；　what　should　we　do？　My　suggestion　is　that　we　pursue　research　and　development　projects　that　can　be　justified　on　their　own　merits　or　by　their　relevance　to　other　goals；　but　that　can　also　contribute　to　human　missions　to　Mars　should　we　later　decide　to　go。　Such　an　agenda　would　include：

·U。S。　astronauts　on　the　Russian　space　station　Mir　for　joint　flights　of　gradually　increasing　duration；　aiming　at　one　to　two　years；　the　Mars　flight　time。

·Configuration　of　the　international　space　station　so　its　principal　function　is　to　study　the　long…term　effects　of　the　space　environment　on　humans。

·Early　implementation　of　a　rotating　or　tethered　〃artificial　gravity〃　module　on　the　international　space　station；　for　other　animals　and　then　for　humans。

·Enhanced　studies　of　the　Sun；　including　a　distributed　set　of　robot　probes　in　orbit　about　the　Sun；　to　monitor　solar　activity　and　give　the　earliest　possible　warning　to　astronauts　of　hazardous　〃solar　flares〃—mass　ejections　of　electrons　and　protons　from　the　Sun's　corona。

·U。S。/Russian　and　multilateral　development　of　Energiya　and　Proton　rocket　technology　for　the　U。S。　and　international　space　programs。　Although　the　United　States　is　unlikely　to　depend　primarily　on　a　Soviet　booster；　Energiya　has　roughly　the　lift　of　the　Saturn　V　that　sent　the　Apollo　astronauts　to　the　Moon。　The　United　States　let　the　Saturn　V　assembly　line　die；　and　it　cannot　readily　be　resuscitated。　Proton　is　the　most　reliable　large　booster　now　in　service。　Russia　is　eager　to　sell　this　technology　for　hard　currency。

·Joint　projects　with　NASDA　（the　Japanese　space　agency）　and　Tokyo　University；　the　European　Space　Agency；　and　the　Russian　Space　Agency；　along　with　Canada　and　other　nations。　In　most　cases　these　should　be　equal　partnerships；　not　the　United　States　insisting　on　calling　the　shots。　For　the　robotic　exploration　of　Mars；　such　programs　are　already　under　way。　For　human　flight；　the　chief　such　activity　is　clearly　the　international　space　station。　Eventually；　we　might　muster　joint　simulated　planetary　missions　in　low　Earth　orbit。　One　of　the　principal　objectives　of　these　programs　should　be　to　build　a　tradition　of　cooperative　technical　excellence。

·Technological　development—using　state…of…the…art　robotics　and　artificial　intelligence—of　rovers；　balloons；　and　aircraft　for　the　exploration　of　Mars；　and　implementation　of　the　first　international　return　sample　mission。　Robotic　spacecraft　that　can　return　samples　from　Mars　can　be　tested　on　near…Earth　asteroids　and　the　Moon。　Samples　returned　from　carefully　selected　regions　of　the　Moon　can　have　their　ages　determined　and　contribute　in　a　fundamental　way　to　our　understanding　of　the　early　history　of　the　Earth。

·Further　development　of　technologies　to　manufacture　fuel　and　oxidizer　out　of　Martian　materials。　In　one　estimate；　based　on　a　prototype　instrument　designed　by　Robert　Zubrin　and　colleagues　at　the　Martin　Marietta　Corporation；　several　kilograms　of　Martian　soil　can　be　automatically　returned　to　Earth　using　a　modest　and　reliable　Delta　launch　vehicle；　all　for　no　more　than　a　song　（paratively　speaking）。

·Simulations　on　Earth　of　long…duration　trips　to　Mars；　concentrating　on　potential　social　and　psychological　problems。

·Vigorous　pursuit　of　new　technologies　such　as　constant…thrust　propulsion　to　get　us　to　Mars　quickly；　this　may　be　essential　if　the　radiation　or　microgravity　hazards　make　one…year　（or　longer）　flight　times　too　risky。

·Intensive　study　of　near…Earth　asteroids；　which　may　provide　superior　intermediate…timescale　objectives　for　human　exploration　than　does　the　Moon。

·A　greater　emphasis　on　science—including　the　fundamental　sciences　behind　space　exploration；　and　the　thorough　analysis　of　data　already　obtained—by　NASA　and　other　space　agencies。

These　remendations　add　up　to　a　fraction　of　the　full　cost　of　a　human　mission　to　Mars　and—spread　out　over　a　decade　or　so　and　done　jointly　with　other　nations—a　fraction　of　current　space　budgets。　But；　if　implemented；　they　would　help　us　to　make　accurate　cost　estimates　and　better　assessment　of　the　dangers　and　benefits。　They　would　permit　us　to　maintain　vigorous　progress　toward　human　expeditions　to　Mars　without　premature　mitment　to　any　specific　mission　hardware。　Most；　perhaps　all；　of　these　remendations　have　other　justifications；　even　if　We　were　sure　wed　be　unable　to　send　humans　to　any　other　world　in　the　next　few　decades。　And　a　steady　drumbeat　of　acplishments　increasing　the　feasibility　of　human　voyages　to　Mars　would—in　the　minds　of　many　at　least—bat　widespread　pessimism　about　the　future。



THERE'S　SOMETHING　MORE。　There's　a　set　of　less　tangible　arguments；　many　of　which；　I　freely　admit；　I　find　attractive　and　resonant。　Spaceflight　speaks　to　something　deep　inside　us—many　of　us；　if　not　all。　An　emerging　cosmic　perspective；　an　improved　understanding　of　our　place　in　the　Universe；　a　highly　visible　program　affecting　our　view　of　ourselves　might　clarify　the　fragility　of　our　planetary　environment　and　the　mon　peril　and　responsibility　of　all　the　nations　and　peoples　of　Earth。　And　human　missions　to　Mars　would　provide　hopeful　prospects；　rich　in　adventure；　for　the　wanderers　among　us；　especially　the　young。　Even　vicarious　exploration　has　social　utility。

I　repeatedly　find　that　when　I　give　talks　on　the　future　of　the　space　program—to　universities；　business　and　military　groups；　professional　organizations—the　audiences　are　much　less　patient　with　practical；　real…world　political　and　economic　obstacles　than　1。　They　long　to　sweep　away　the　impediments；　to　recapture　the　glory　days　of　Vostok　and　Apollo；　to　get　on　with　it　and　once　more　tread　other　worlds。　We　did　it　before；　we　can　do　it　again；　they　say。　But；　I　caution　myself；　those　who　attend　such　talks　are　self…selected　space　enthusiasts。

In　1969；　less　than　half　the　American　people　thought　the　Apollo　program　was　worth　the　cost。　But　on　the　twenty…fifth　anniversary　of　the　Moon　landing；　the　number　had　risen　to　two　thirds。　Despite　its　problems；　NASA　was　rated　as　doing　a　good…to…excellent　job　by　63　percent　of　Americans。　With　no　reference　to　cost；　75　percent　of　Americans　（according　to　a　CBS　News　poll）　favored　〃the　United　States　sending　astronauts　to　explore　Mars。'　For　young　adults；　the　figure　was　68　percent。　I　think　〃explore〃　is　the　operative　word。

It　is　no　accident　that；　whatever　their　human　flaws；　and　how　ever　moribund　the　human　space　program　has　bee　（a　trend　that　the　Hubble　Space　Telescope　repair　mission　may　have　helped　to　reverse）；　astronauts　and　cosmonauts　are　still　widely　regarded　as　heroes　of　our　species。　A　scientific　colleague　tells　me　about　a　recent　trip　to　the　New　Guinea　highlands　where　she　visited　a　stone　age　culture　hardly　contacted　by　Western　civilization。　They　were　ignorant　of　wristwatches；　soft　drinks；　and　frozen　food。　But　they　knew　about　Apollo　11。　They　knew　that　humans　had　walked　on　the　Moon。　They　knew　the　names　of　Armstrong　and　Aldrin　and　Collins。　They　wanted　to　know　who　was　visiting　the　Moon　these　days。

Projects　that　are　future…oriented；　that；　despite　their　political　difficulties；　can　be　pleted　only　in　some　distant　decade　are　continuing　reminders　that　there　will　be　a　future。　Winning　a　foothold　on　other　worlds　whispers　in　our　ears　that　we're　more　than　Picts　or　Serbs　or　Tongans：　We're　humans。

Exploratory　spaceflight　puts　scientific　ideas；　scientific　thinking；　and　scientific　vocabulary　in　the　public　eye。　It　elevates　the　general　level　of　intellectual　inquiry。　The　idea　that　we've　now　understood　something　never　grasped　by　anyone　who　ever　lived　before—that　exhilaration；　especially　intense　for　the　scientists　involved；　but　perceptible　to　nearly　everyone—propagates　through　the　society；　bounces　off　walls；　and　es　back　at　us。　It　encourages　us　to　address　problems　in　other　fields　that　have　also　never　before　been　solved。　It　increases　the　general　sense　of　optimism　in　the　society。　It　gives　currency　to　critical　thinking　of　the　sort　urgently　needed　if　we　are　to　solve　hitherto　intractable　social　issues。　It　helps　stimulate　a　new　generation　of　scientists。　The　more　science　in　the　media…especially　if　methods　are　described；　as　well　as　conclusions　and　implications…the　healthier；　I　believe；　the　society　is。　People　everywhere　hunger　to　understand。



WHEN　I　WAS　A　CHILD；　my　most　exultant　dreams　were　about　flying—not　in　some　machine；　but　all　by　myself。　I　would　be　skipping　or　hopping；　and　slowly　I　could　pull　my　trajectory　higher。　It　would　take　longer　to　fall　back　to　the　ground。　Soon　I　would　be　on　such　a　high　arc　that　I　wouldn't　e　down　at　all。　I　would　alight　like　a　gargoyle　in　a　niche　near　the　pinnacle　of　a　skyscraper；　or　gently　settle　down　on　a　cloud。　In　the　dream—which　I　must　have　had　in　its　many　variations　at　least　a　hundred　times—achieving　flight　required　a　certain　cast　of　mind。　It's　impossible　to　describe　it　in　words；　but　I　can　remember　what　it　was　like　to　this　day。　You　did　something　inside　your　head　and　at　the　pit　of　your　stomach；　and　then　you　could　lift　yourself　up　by　an　effort　of　will　alone；　your　limbs　hanging　limply。　Off　you'd　soar。

I　know　many　people　have　ha