pale blue dot -carl sagan- 第38部分

The　crews　would　acquire　new　and　previously　sequestered　samples；　in　part　to　search　for　life；　in　part　to　understand　the　past　and　future　of　Mars　and　Earth。　They　would　experiment；　for　later　expeditions；　on　extracting　water；　oxygen；　and　hydrogen　from　the　rocks　and　the　air　and　from　the　underground　permafrost—to　drink；　to　breathe；　to　power　their　machines　and；　as　rocket　fuel　and　oxidizer；　to　propel　the　return　voyage。　They　would　test　Martian　materials　for　eventual　fabrication　of　bases　and　settlements　on　Mars。

And　they　would　go　exploring。　When　I　imagine　the　early　human　exploration　of　Mars；　it's　always　a　roving　vehicle；　a　little　like　a　jeep；　wandering　down　one　of　the　valley　networks；　the　crew　with　geological　hammers；　cameras；　and　analytic　instruments　at　the　ready。　They're　looking　for　rocks　from　ages　past；　signs　of　ancient　cataclysms；　clues　to　climate　change；　strange　chemistries；　fossils；　or—most　exciting　and　most　unlikely—something　alive。　Their　discoveries　are　televised　back　to　Earth　at　the　speed　of　light。　Snuggled　up　in　bed　with　the　kids；　you　explore　the　ancient　riverbeds　of　Mars。




CHAPTER　16　　　SCALING　HEAVEN

　

　

Who；　my　friend；　can　scale　heaven？

—THE　EPIC　OF　GILGAMESH　（SUMER；　THIRD　MILLENNIUM　B。C。）

What？；　I　sometimes　ask　myself　in　amazement：　Our　ancestors　walked　from　East　Africa　to　Novaya　Zemlya　and　Ayers　Rock　and　Patagonia；　hunted　elephants　with　stone　spearpoints；　traversed　the　polar　seas　in　open　boats　7；000　years　ago；　circumnavigated　the　Earth　propelled　by　nothing　but　wind；　walked　the　Moon　a　decade　after　entering　space—and　we're　daunted　by　a　voyage　to　Mars？　But　then　I　remind　myself　of　the　avoidable　human　suffering　on　Earth；　how　a　few　dollars　can　save　the　life　of　a　child　dying　of　dehydration；　how　many　children　we　could　save　for　the　cost　of　a　trip　to　Mars—and　for　the　moment　I　change　my　mind。　Is　it　unworthy　to　stay　home　or　unworthy　to　go？　Or　have　I　posed　a　false　dichotomy？　Isn't　it　possible　to　make　a　better　life　for　everyone　on　Earth　and　to　reach　for　the　planets　and　the　stars？

We　had　an　expansive　run　in　the　'60s　and　'70s。　You　might　have　thought；　as　I　did　then；　that　our　species　would　be　on　Mars　before　the　century　was　over。　But　instead；　we've　pulled　inward。　Robots　aside；　we've　backed　off　from　the　planets　and　the　stars。　1　keep　asking　myself　Is　it　a　failure　of　nerve　or　a　sign　of　maturity？

Maybe　it's　the　most　we　could　reasonably　have　expected。　In　a　way　it's　amazing　that　it　was　possible　at　all：　We　sent　a　dozen　humans　on　week…long　excursions　to　the　Moon。　And　we　were　given　the　resources　to　make　a　preliminary　reconnaissance　of　the　whole　Solar　System；　out　to　Neptune　anyway—missions　that　returned　a　wealth　of　data；　but　nothing　of　short…term；　everyday；　bread…on…the…table　practical　value。　They　lifted　the　human　spirit；　though。　They　enlightened　us　about　our　place　in　the　Universe。　It's　easy　to　imagine　skeins　of　historical　causality　in　which　there　were　no　race　to　the　Moon　and　no　planetary　program。

But　it's　also　possible　to　imagine　a　much　more　serious　devotion　to　exploration；　because　of　which　we　would　today　have　robot　vehicles　probing　the　atmospheres　of　all　the　Jovian　planets　and　dozens　of　moons；　ets；　and　asteroids；　a　network　of　automatic　scientific　stations　emplaced　on　Mars　would　daily　be　reporting　their　findings；　and　samples　from　many　worlds　would　be　under　examination　in　the　laboratories　of　Earth—revealing　their　geology；　chemistry；　and　perhaps　even　their　biology。　Human　outposts　might　be　already　established　on　the　near…Earth　asteroids；　the　Moon；　and　Mars。

There　were　many　possible　historical　paths。　Our　particular　causality　skein　has　brought　us　to　a　modest　and　rudimentary；　although　in　many　respects　heroic；　series　of　explorations。　But　it　is　far　interior　to　what　might　have　been—and　what　may　one　day　be。



TO　CARRY　THE　GREEN　Promethean　spark　of　Life　with　us　into　the　sterile　void　and　ignite　there　a　firestorm　of　animate　matter　is　the　very　destiny　of　our　race；〃　reads　the　brochure　of　something　called　the　First　Millennial　Foundation。　It　promises；　for　120　a　year；　〃citizenship〃　in　〃space　colonies—when　the　time　es。〃　〃Benefactors〃　who　contribute　more　also　receive　〃the　undying　gratitude　of　a　star…flung　civilization；　and　their　name　carved　on　the　monolith　to　be　erected　on　the　Moon。〃　This　represents　one　extreme　in　the　continuum　of　enthusiasm　for　a　human　presence　in　space。　The　other　extreme—better　represented　in　Congress—questions　why　we　should　be　in　space　at　all；　especially　people　rather　than　robots。　The　Apollo　program　was　a　〃moondoggle；〃　the　social　critic　Amitai　Etzioni　once　called　it；　with　the　Cold　War　over；　there　is　no　justification　whatever；　proponents　of　this　orientation　hold；　for　a　manned　space　program。　Where　in　this　spectrum　of　policy　options　should　we　be？

Ever　since　the　United　States　beat　the　Soviet　Union　to　the　Moon；　a　coherent；　widely　understood　justification　for　humans　in　space　seems　to　have　vanished。　Presidents　and　Congressional　mittees　puzzle　over　what　to　do　with　the　manned　space　program。　What　is　it　for？　Why　do　we　need　it？　But　the　exploits　of　the　astronauts　and　the　moon　landings　had　elicited—and　for　good　reason—the　admiration　of　the　world。　It　would　be　a　rejection　of　that　stunning　American　achievement；　the　political　leaders　tell　themselves；　to　back　off　from　manned　spaceflight。　Which　President；　which　Congress　wishes　to　be　responsible　for　the　end　of　the　American　space　program？　And　in　the　former　Soviet　Union　a　similar　argument　is　heard：　Shall　we　abandon；　they　ask　themselves；　the　one　remaining　high　technology　in　which　we　are　still　world　leaders？　Shall　we　be　faithless　heirs　of　Konstantin　Tsiolkovsky；　Sergei　Korolev；　and　Yuri　Gagarin？

The　first　law　of　bureaucracy　is　to　guarantee　its　own　continuance。　Left　to　its　own　devices；　without　clear　instructions　from　above；　NASA　gradually　devolved　into　a　program　that　would　maintain　profits；　jobs；　and　perquisites。　Pork…barrel　politics；　with　Congress　playing　a　leading　role；　became　an　increasingly　powerful　force　in　the　design　and　execution　of　missions　and　long…term　goals。　The　bureaucracy　ossified。　NASA　lost　its　way。

On　July　20；　1989；　the　twentieth　anniversary　of　the　Apollo　11　landing　on　the　Moon；　President　George　Bush　announced　a　long…term　direction　for　the　U。S。　space　program。　Called　the　Space　Exploration　Initiative　（SEI）；　it　proposed　a　sequence　of　goals　including　a　U。S。　space　station；　a　return　of　humans　to　the　Moon；　and　the　first　landing　of　humans　on　Mars。　In　a　later　statement；　Mr。　Bush　set　2019　as　the　target　date　for　the　first　footfall　on　that　planet。

And　yet　the　Space　Exploration　Initiative；　despite　clear　direction　from　the　top；　foundered。　Four　years　after　it　was　mandated；　it　did　not　even　have　a　NASA　office　dedicated　to　it。　Small　and　inexpensive　lunar　robotic　missions—that　otherwise　might　well　have　been　approved—were　canceled　by　Congress　because　of　guilt　by　association　with　SEI。　What　went　wrong？

One　problem　was　the　timescale。　SEI　extended　five　or　so　presidential　terms　of　office　into　the　future　（taking　the　average　presidency　as　one　and　a　half　terms）。　That　makes　it　easy　for　a　president　to　attempt　to　mit　his　successors；　but　leaves　in　considerable　doubt　how　reliable　such　a　mitment　might　be。　SEI　contrasted　dramatically　with　the　Apollo　program—which；　it　might　have　been　conjectured　at　the　time　it　began；　could　have　triumphed　when　President　Kennedy　or　his　immediate　political　heir　was　still　in　office。

Second；　there　was　concern　about　whether　NASA；　which　had　recently　experienced　great　difficulty　in　safely　lifting　a　few　astronauts　200　miles　above　the　Earth；　could　send　astronauts　on　an　arcing　year…long　trajectory　to　a　destination　100　million　miles　away　and　bring　them　back　alive。

Third；　the　program　was　conceived　exclusively　in　nationalist　terms。　Cooperation　with　other　nations　was　not　fundamental　to　either　design　or　execution。　Vice　President　Dan　Quayle；　who　had　nominal　responsibility　for　space；　justified　the　space　station　as　a　demonstration　that　the　United　States　was　〃the　world's　only　superpower。〃　But　since　the　Soviet　Union　had　an　operational　space　station　that　was　a　decade　ahead　of　the　United　States；　Mr。　Quayle's　argument　proved　difficult　to　follow。

Finally；　there　was　the　question　of　where；　in　terms　of　practical　politics；　the　money　was　supposed　to　e　from。　The　costs　of　getting　the　first　humans　to　Mars　had　been　variously　estimated；　ranging　as　high　as　500　billion。

Of　course；　it's　impossible　to　predict　costs　before　you　have　a　mission　design。　And　the　mission　design　depends　on　such　matters　as　the　size　of　the　crew；　the　extent　to　which　you　take　mitigating　steps　against　solar　and　cosmic　radiation　hazards；　or　zero　gravity；　and　what　other　risks　you　are　willing　to　accept　with　the　lives　of　the　men　and　women　on　board。　If　every　crew　member　has　one　essential　specialty；　what　happens　if　one　of　them　falls　ill？　The　larger　the　crew；　the　more　reliable　the　backups。　You　would　almost　certainly　not　send　a　full…time　oral　surgeon；　but　what　happens　if　you　need　root　canal　work　and　you're　a　hundred　million　miles　from　the　nearest　dentist？　Or　could　it　be　done　by　an　endodontist　on　Earth；　using　telepresence？

Wernher　von　Braun　was　the　Nazi…American　engineer　who；　more　than　anyone　else；　actually　took　us　into　space。　His　1952　book　Das　Marsprojekt　envisioned　a　first　mission　with　10　interplanetary　spacecraft；　70　crew　members；　and　3　〃landing　boats。〃　Redundancy　was　uppermost　in　his　mind。　The　logistical　requirements；　he　wrote；　〃are　no　greater　than　those　for　a　minor　military　operation　extending　over　a　limited　theater　of　war。〃　He　meant　to　〃explode　once　and　for　all　the　theory　of　the　solitary　space　rocket　and　its　little　band　of　bold　interplanetary　adventurers；〃　and　appealed　to　Columbus'　three　ships　without　which　〃history　tends　to　prove　that　he　might　never　have　returned　to　Spanish　shores。〃　Modern　Mars　mission　designs　have　ignored　this　advice。　They　are　much　less　ambitious　than　yon　Braun's；　typically　calling　for　one　or　two　spacecraft　crewed　by　three　to　eight　astronauts；　with　another　robotic　cargo　ship　or　two。　The　solitary　rocket　and　the　little　band　of　adventurers　are　still　with　us。

Other　uncertainties　affecting　mission　design　and　cost　include　whether　you　pre…emplace　supplies　from　Earth　and　launch　humans　to　Mars　only　after　the　supplies　are　safely　landed；　whether　you　can　use　Martian　materials　to　generate　oxygen　to