pale blue dot -carl sagan-第24部分

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　launches　to　get　there。　Averaging　the　shaky　start　and　the　better　recent　performance；　we　find　that　both　the　United　States　and　Russia　have　a　cumulative　launch　success　rate　of　about　80　percent。　But　the　cumulative　mission　success　rate　is　still　under　70　percent　for　the　U。S。　and　under　60　percent　for　the　U。S。S。R。/Russia。　Equivalently；　lunar　and　planetary　missions　have　failed　on　average　30　or　40　percent　of　the　time。

Missions　to　other　worlds　were　from　the　beginning　at　the　cutting　edge　of　technology。　They　continue　to　be　so　today。　They　。ire　designed　with　redundant　subsystems；　and　operated　by　dedicated　and　experienced　engineers；　but　they　are　not　perfect。　The　amazing　thing　is　not　that　we　have　done　so　poorly；　but　that　we　leave　done　so　well。

We　don't　know　whether　the　Mars　Observer　failure　was　due　to　inpetence　or　just　statistics。　But　we　must　expect　a　steady　background　of　mission　failures　when　we　explore　other　worlds。　No　human　lives　are　risked　when　a　robot　spacecraft　is　lost。　Even　if　we　were　able　to　improve　this　success　rate　significantly；　it　would　be　far　too　costly。　It　is　much　better　to　take　more　risks　and　fly　more　spacecraft：。

Knowing　about　irreducible　risks；　why　do　we　these　days　fly　only　one　spacecraft　per　mission？　In　1962　Mariner　1；　intended　for　Venus；　fell　into　the　Atlantic；　the　nearly　identical　Mariner　2　became　the　human　species'　first　successful　planetary　mission。　Mariner　3　failed；　arid　its　twin　Mariner　4　became；　in　1964；　the　first　spacecraft　to　take　close…up　pictures　of　Mars。　Or　consider　the　1971　Mariner　8/Mariner　9　dual　launch　mission　to　Mars。　Mariner　8　Was　to　map　the　planet。　Mariner　9　was　to　study　the　enigmatic　seasonal　and　secular　changes　of　surface　markings。　The　spacecraft　were　otherwise　identical。　Mariner　8　fell　into　the　ocean。　Mariner　9　flew　on　to　Mars　arid　became　the　first　spacecraft　in　human　history　to　orbit　another　planet。　It　discovered　the　volcanos；　the　laminated　terrain　in　the　polar　caps；　the　ancient　river　valleys；　and　the　aeolian　nature　of　the　surface　changes。　It　disproved　the　〃canals。〃　It　mapped　the　planet　pole　to　pole　and　revealed　all　the　major　geological　features　of　Mars　known　to　us　today。　It　provided　the　first　close…up　observations　of　members　of　a　whole　class　of　small　worlds　（by　targeting　the　Martian　moons；　Phobos　and　Deimos）。　If　we　had　launched　only　Mariner　8；　the　endeavor　would　have　been　an　unmitigated　failure。　With　a　dual　launch　it　became　a　brilliant　and　historic　success。

There　were　also　two　Vikings；　two　Voyagers；　two　Vegas；　many　pairs　of　Veneras。　Why　was　only　one　Mars　Observer　flown？　The　standard　answer　is　cost。　Part　of　the　reason　it　was　so　costly；　though；　is　that　it　was　planned　to　be　launched　by　shuttle；　which　is　an　almost　absurdly　expensive　booster　for　planetary　missions—in　this　case　too　expensive　for　two　M。　O。　launches。　After　many　shuttle…connected　delays　and　cost　increases；　NASA　changed　its　mind　and　decided　to　launch　Mars　Observer　on　a　Titan　booster。　This　required　an　additional　two…year　delay　and　an　adapter　to　mate　the　spacecraft　to　the　new　launch　vehicle。　If　NASA　had　not　been　so　intent　on　providing　business　for　the　increasingly　uneconomic　shuttle；　we　could　have　launched　a　couple　of　years　earlier　and　maybe　with　two　spacecraft　instead　of　one。

But　whether　in　single　launches　or　in　pairs；　the　space…faring　nations　have　clearly　decided　that　the　time　is　ripe　to　return　robot　explorers　to　Mars。　Mission　designs　change；　new　nations　enter　the　field；　old　nations　find　they　no　longer　have　the　resources。　Even　already　funded　programs　cannot　always　be　relied　upon。　But　current　plans　do　reveal　something　of　the　intensity　of　effort　and　the　depth　of　dedication。

As　I　write　this　book；　there　are　tentative　plans　by　the　United　States；　Russia；　France；　Germany；　Japan；　Austria；　Finland；　Italy；　Canada；　the　European　Space　Agency；　and　other　entities　for　a　coordinated　robotic　exploration　of　Mars。　In　the　seven　years　between　1996　and　2003；　a　flotilla　of　some　twenty…five　spacecraft—most　of　them　paratively　small　and　cheap—are　to　be　sent　from　Earth　to　Mars。　There　will　be　no　quick　flybys　among　them；　these　are　all　long…duration　orbiter　and　lander　missions。　The　United　States　will　re…fly　all　of　the　scientific　instruments　that　were　lost　on　Mars　Observer。　The　Russian　spacecraft　will　contain　particularly　ambitious　experiments　involving　some　twenty　nations。　munications　satellites　will　permit　experimental　stations　anywhere　on　Mars　to　relay　their　data　back　to　Earth。　Penetrators　screeching　down　from　orbit　will　punch　into　the　Martian　soil；　transmitting　data　from　underground。　Instrumented　balloons　and　roving　laboratories　will　wander　over　the　sands　of　Mars。　Some　microrobots　will　weigh　no　more　than　a　few　pounds。　Landing　sites　are　being　planned　and　coordinated。　Instruments　will　be　cross…calibrated。　Data　will　be　freely　exchanged。　There　is　every　reason　to　think　that　in　the　ing　years　Mars　and　its　mysteries　will　bee　increasingly　familiar　to　the　inhabitants　of　the　planet　Earth。



IN　THE　MAND　CENTER　on　Earth；　in　a　special　room；　you　are　helmeted　and　gloved。　You　turn　your　head　to　the　left；　and　the　cameras　on　the　Mars　robot　rover　turn　to　the　left。　You　see；　in　very　high　definition　and　in　color；　what　the　cameras　see。　You　take　a　step　forward；　and　the　rover　walks　forward。　You　reach　out　your　arm　to　pick　up　something　shiny　in　the　soil；　and　the　robot　arm　does　likewise。　The　sands　of　Mars　trickle　through　your　fingers。　The　only　difficulty　with　this　remote　reality　technology　is　that　all　this　must　occur　in　tedious　slow　motion：　The　round…trip　travel　time　of　the　up…link　mands　from　Earth　to　Mars　and　the　down…link　data　returned　from　Mars　to　Earth　might　take　half　an　hour　or　more。　But　this　is　something　we　can　learn　to　do。　We　can　learn　to　contain　our　exploratory　impatience　if　that's　the　price　of　exploring　Mars。　The　rover　can　be　made　smart　enough　to　deal　with　routine　contingencies。　Anything　more　challenging；　and　it　makes　a　dead　stop；　puts　itself　into　a　safeguard　mode；　and　radios　for　a　very　patient　human　controller　to　take　over。

Conjure　up　roving；　smart　robots；　each　of　them　a　small　scientific　laboratory；　landing　in　the　safe　but　dull　places　and　wandering　to　view　close…up　some　of　that　profusion　of　Martian　Wonders。　Perhaps　every　day　a　robot　would　rove　to　its　own　horizon；　each　morning　we　would　see　close…up　what　had　yesterday　been　only　a　distant　eminence。　The　lengthening　progress　of　a　traverse　route　over　the　Martian　landscape　would　appear　oil　news　programs　and　in　schoolrooms。　People　would　speculate　on　what　will　be　found。　Nightly　newscasts　from　another　planet；　with　their　revelations　of　new　terrains　and　new　scientific　findings　would　make　everyone　on　Earth　a　party　to　the　adventure。

Then　there's　Martian　virtual　reality：　The　data　sent　back　from　Mars；　stored　in　a　modern　puter；　are　fed　into　your　helmet　and　gloves　and　boots。　You　are　walking　in　an　empty　room　on　Earth；　but　to　you　you　are　on　Mars：　pink　skies；　fields　of　boulders；　sand　dunes　stretching　to　the　horizon　where　an　immense　volcano　looms；　you　hear　the　sand　crunching　under　your　boots；　you　turn　rocks　over；　dig　a　hole；　sample　the　thin　air；　turn　a　corner；　and　e　face　to　face　with　。　。　。　whatever　new　discoveries　we　will　make　on　Mars—all　exact　copies　of　what's　on　Mars；　and　all　experienced　from　the　safety　of　a　virtual　reality　salon　in　your　hometown。　This　is　not　why　we　explore　Mars；　but　clearly　we　will　need　robot　explorers　to　return　the　real　reality　before　it　can　be　reconfigured　into　virtual　reality。

Especially　with　continuing　investment　in　robotics　and　machine　intelligence；　sending　humans　to　Mars　can't　be　justified　by　science　alone。　And　many　more　people　can　experience　the　virtual　Mars　than　could　possibly　be　sent　to　the　real　one。　We　can　do　very　well　with　robots。　If　we're　going　to　send　people；　we'll　need　a　better　reason　than　science　and　exploration。

In　the　1980s；　I　thought　I　saw　a　coherent　justification　for　human　missions　to　Mars。　I　imagined　the　United　States　and　the　Soviet　Union；　the　two　Cold　War　rivals　that　had　put　our　global　civilization　at　risk；　joining　together　in　a　far…seeing；　high…technology　endeavor　that　would　give　hope　to　people　everywhere。　I　pictured　a　kind　of　Apollo　program　in　reverse；　in　which　cooperation；　not　petition；　was　the　driving　force；　in　which　tire　two　leading　space…faring　nations　would　together　lay　the　groundwork　for　a　major　advance　in　human　history—the　eventual　settlement　of　another　planet。

The　symbolism　seemed　so　apt。　The　same　technology　that　can　propel　apocalyptic　weapons　from　continent　to　continent　would　enable　the　first　human　voyage　to　another　planet。　It　was　a　choice　of　fitting　mythic　power：　to　embrace　the　planet　named　after；　rather　the　madness　ascribed　to；　the　god　of　war。

We　succeeded　in　interesting　Soviet　scientists　and　engineers　in　such　a　joint　endeavor。　Roald　Sagdeev；　then　director　of　the　Institute　for　Space　Research　of　the　Soviet　Academy　of　Sciences　in　Moscow；　was　already　deeply　engaged　in　international　cooperation　on　Soviet　robotic　missions　to　Venus；　Mars；　and　Halley's　et；　long　before　the　idea　became　fashionable。　Projected　joint　use　of　the　Soviet　Mir　space　station　and　the　Saturn　V…class　launch　vehicle　Energiya　made　cooperation　attractive　to　the　Soviet　organizations　that　manufactured　these　items　of　hardware；　they　were　otherwise　having　difficulty　justifying　their　wares。　Through　a　sequence　of　arguments　（helping　to　bring　the　Cold　War　to　an　end　being　chief　among　them）；　then…Soviet　leader　Mikhail　S。　Gorbachev　was　convinced。　During　the　December　1987　Washington　summit；　Mr。　Gorbachev—asked　what　was　the　most　important　joint　activity　through　which　the　two　countries　might　symbolize　the　change　in　their　relationship—unhesitatingly　replied；　〃Let's　go　to　Mars　together。〃

But　the　Reagan　Administration　was　not　interested。　Cooperating　with　the　Soviets；　acknowledging　that　certain　Soviet　technologies　were　more　advanced　than　their　American　counterparts；　making　some　American　technology　available　to　the　Soviets；　sharing　credit；　providing　an　alternative　for　the　arms　manufacturers—these　were　not　to　the　Administration's　liking。　The　offer　was　turned　down。　Mars　would　have　to　wait。

In　only　a　few　years；　times　have　changed。　The　Cold　War　is　over。　The　Soviet　Union　is　no　more。　The　benefit　deriving　from　the　two　nations　working　together　has　lost　some　of　its　force。　Other　nations—especially　Japan　and　the　constituent　members　of　the　European　Space　Agency—have　bee　interplanetary　travelers。　Many　just　and　urgent　demands　are　levied　on　the　discretionary　budgets　of　the　nations。

But　the　Energiya　heavy…lift　booster　still　awaits　a　mission。　The　workhorse　Proton　rocket　is　available。　The　Mir　space　station—with　a　crew　on　board　almost　continuously—still　orbits　the　Earth　every　hour　and　a　half。　Despite　internal　turmoil；　the　Russian　space　program　continues　vigorously。　Cooperation　between　Russia　and　America　in　space　is　accelerating。　A　Russian　cosmonaut；　Sergei　Krikalev；　in　1994　flew　on　the　shuttle　Discovery　（for　the　usual　one…week　shuttle　mission　duration；　Krikalev　had　already　logged　464　days　aboard　the　Mir　space　station）。　U。S。　astronauts　will　visit　Mir。　American　instruments—including　one　to　examine　the　oxidants　thought　to　destroy　organic　molecules　in　the　Martian　soil—are　to　be　carried　by　Russian　space　vehicles　to　Mars。　Mars　Observer　was　designed　to　serve　as　a　relay　station　for　landers　in　Russian　Mars　missions。　The　Russians　have　offered　to　include　a　U。S。　orbiter　in　a　forthing　Proton…launched　multipayload　mission　to　Mars。

The　American　and　Russian　capabilities　in　space　science　and　technology　mesh；　they　interdigitate。　Each　is　strong　where　the　other　is　weak。　This　is　a　marriage　made　in　heaven…but　one　that　has　been　surprisingly　difficult　to　consummate。

On　September　2；　1993；　an　agreement　to　cooperate　in　depth　was　signed　in　Washington　by　Vice　President　Al　Gore　and　Prime　Minister　Viktor　Chernomyrdin。　The　Clinton　Administration　has　ordered　NASA　to　redesign　the　U。S。　space　station　（called　Freedom　in　the　Reagan　years）　so　it　is　in　the　same　orbit　as　Mir　and　can　be　mated　to　it：　Japanese　and　European　modules　will　be　attached；　as　will　a　Canadian　robot　arm。　The　designs　have　now　evolved　into　what　is　called　Space　Station　Alpha；　involving　almost　all　the　spacefaring　nations。　（China　is　the　most　notable　exception。）

In　return　for　U。S。　space　cooperation　and　an　infusion　of　hard　currency；　Russia　in　effect　agreed　to　halt　its　sale　of　ballistic　missile　ponents　to　other　nations；　and　generally　to　exercise　tight　controls　on　its　export　of　strategic　weapons　technology。　In　this　Way；　space　bees　once　again；　as　it　was　at　the　height　of　the　Cold　War；　an　instrument　of　national　strategic　policy。

This　new　trend　has；　though；　made　some　of　the　American　aerospace　industry　and　some　key　members　of　Congress　profoundly　uneasy。　Without　international　petition；　can　we　motivate　such　ambitious　efforts？　Does　every　Russian　launch　vehicle　used　cooperatively　mean　less　support　for　the　American　aerospace　industry？　Can　Americans　rely　on　stable　support　and　continuity　of　effort　in　joint　projects　with　the　Russians？　（The　Russians；　of　course；　ask　similar　questions　about　the　Americans。）　But　cooperative　programs　in　the　long　term　save　money；　draw　upon　the　extraordinary　scientific　and　engineering　talent　distributed　over　our　planet；　and　provide　inspiration　about　the　global　future。　There　may　be　fluctuations　in　national　mitments。　We　are　likely　to　take　backward　as　well　as　forward　steps。　But　the　overall　trend　seems　clear。

Despite　growing　pains；　the　space　programs　of　the　two　former　adversaries　are　beginning　to　join。　It　is　now　possible　to　foresee　a　world　space　station—not　of　any　one　nation　but　of　the　planet　Earth—being　assembled　at　51°　inclination　to　the　equator　and　a　few　hundred　miles　up。　A　dramatic　joint　mission；　called　〃Fire　and　Ice；〃　is　being　discussed　in　which　a　fast　flyby　would　be　sent　to　Pluto；　the　last　unexplored　planet；　but　to　get　there；　a　gravity　assist　from　the　Sun　would　be　employed；　in　the　course　of　Which　small　probes　would　actually　enter　the　Sun's　atmosphere。　And　we　seem　to　be　on　the　threshold　of　a　World　Consortium　for　the　scientific　exploration　of　Mars。　It　very　much　looks　as　though　such　projects　will　be　done　cooperatively　or　not　at　all。



WHETHER　THERE　ARE　VALID；　cost…effective；　broadly　supportable　reasons　for　people　to　venture　to　Mars　is　an　open　question。　Certainly　there　is　no　consensus。　The　matter　is　treated　in　the　next　chapter。

I　would　argue　that　if　we　are　not　eventually　going　to　send　people　to　worlds　as　far　away　as　Mars；　we　have　lost　the　chief　reason　for　a　space　station—a　permanently　（or　intermittently）　occupied　human　outpost　in　Earth　orbit。　A　space　station　is　far　from　an　optimum　platform　for　doing　science　either　looking　down　at　the　Earth；　or　looking　out　into　space；　or　for　utilizing　microgravity　（the　very　presence　of　astronauts　messes　things　up）。　For　military　reconnaissance　it　is　much　inferior　to　robotic　spacecraft。　There　are　no　pelling　economic　or　manufacturing　applications。　It　is　expensive　pared　to　robotic　spacecraft。　And　of　course　it　runs　some　risk　of　losing　human　lives。　Every　shuttle　launch　to　help　build　or　supply　a　space　station　has　an　estimated　1　or　2　percent　chance　of　catastrophic　failure。　Previous　civilian　and　military　space　activities　have　littered　low　Earth　orbit　with　fast…moving　debris—that　sooner　or　later　will　collide　with　a　space　station　（although；　so　far；　Mir　has　had　no　failures　from　this　hazard）。　A　space　station　is　also　unnecessary　for　human　exploration　of　the　Moon。　Apollo　got　there　ve