pale blue dot -carl sagan- 第58节

Can　we　humans　be　trusted　with　civilization…threatening　technologies？　If　the　chance　is　almost　one　in　a　thousand　that　much　of　the　human　population　will　be　killed　by　an　impact　in　the　next　century；　isn't　it　more　likely　that　asteroid　deflection　technology　will　get　into　the　wrong　hands　in　another　century—some　misanthropic　sociopath　like　a　Hitler　or　a　Stalin　eager　to　kill　everybody；　a　megalomaniac　lusting　after　〃greatness〃　and　〃glory；〃　a　victim　of　ethnic　violence　bent　on　revenge；　someone　in　the　grip　of　unusually　severe　testosterone　poisoning；　some　religious　fanatic　hastening　the　Day　of　judgment；　or　just　technicians　inpetent　or　insufficiently　vigilant　in　handling　the　controls　and　safeguards？　Such　people　exist。　The　risks　seem　far　worse　than　the　benefits；　the　cure　worse　than　the　disease。　The　cloud　of　near…Earth　asteroids　through　which　the　Earth　plows　may　constitute　a　modern　Camarine　marsh。

It's　easy　to　think　that　all　of　this　must　be　very　unlikely；　mere　anxious　fantasy。　Surely　sober　heads　would　prevail。　Think　of　how　many　people　would　be　involved　in　preparing　and　launching　warheads；　in　space　navigation；　in　detonating　warheads；　in　checking　what　orbital　perturbation　each　nuclear　explosion　has　made；　in　herding　the　asteroid　so　it　is　on　an　impact　trajectory　with　Earth；　and　so　on。　Isn't　it　noteworthy　that　although　Hitler　gave　orders　for　the　retreating　Nazi　troops　to　burn　Paris　and　to　lay　waste　to　Germany　itself；　his　orders　were　not　carried　out？　Surely　someone　essential　to　the　success　of　the　deflection　mission　will　recognize　the　danger。　Even　assurances　that　the　project　is　designed　to　destroy　some　vile　enemy　nation　would　probably　be　disbelieved；　because　the　effects　of　collision　are　planet…wide　（and　anyway　it's　very　hard　to　make　sure　your　asteroid　excavates　its　monster　crater　in　a　particularly　deserving　nation）。

But　now　imagine　a　totalitarian　state；　not　overrun　by　enemy　troops；　but　one　thriving　and　self…confident。　Imagine　a　tradition　in　which　orders　are　obeyed　without　question。　Imagine　that　those　involved　in　the　operation　are　supplied　a　cover　story：　The　asteroid　is　about　to　impact　the　Earth；　and　it　is　their　job　to　deflect　it—but　in　order　not　to　worry　people　needlessly；　the　operation　must　be　performed　in　secret。　In　a　military　setting　with　a　mand　hierarchy　firmly　in　place；　partmentalization　of　knowledge；　general　secrecy；　and　a　cover　story；　can　we　be　confident　that　even　apocalyptic　orders　would　be　disobeyed？　Are　we　really　sure　that　in　the　next　decades　and　centuries　and　millennia；　nothing　like　this　might　happen？　How　sure　are　we？

It's　no　use　saying　that　all　technologies　can　be　used　for　good　or　for　ill。　That　is　certainly　true；　but　when　the　〃ill〃　achieves　a　sufficiently　apocalyptic　scale；　we　may　have　to　set　limits　on　which　technologies　may　be　developed。　（In　a　way　we　do　this　all　the　time；　because　we　can't　afford　to　develop　all　technologies。　Some　are　favored　and　some　are　not。）　Or　constraints　may　have　to　be　levied　by　the　munity　of　nations　on　madmen　and　autarchs　and　fanaticism。

Tracking　asteroids　and　ets　is　prudent；　it's　good　science；　and　it　doesn't　cost　much。　But；　knowing　our　weaknesses；　why　would　we　even　consider　now　developing　the　technology　to　deflect　small　worlds？　For　safety；　shall　we　imagine　this　technology　in　the　hands　of　many　nations；　each　providing　checks　and　balances　against　misuse　by　another？　This　is　nothing　like　the　old　nuclear　balance　of　terror。　It　hardly　inhibits　some　madman　intent　on　global　catastrophe　to　know　that　if　he　does　not　hurry；　a　rival　may　beat　him　to　it。　How　confident　can　we　be　that　the　munity　of　nations　will　be　able　to　detect　a　cleverly　designed；　clandestine　asteroid　deflection　in　time　to　do　something　about　it？　If　such　a　technology　were　developed；　can　any　international　safeguards　be　envisioned　that　have　a　reliability　mensurate　with　the　risk？

Even　if　we　restrict　ourselves　merely　to　surveillance；　there's　a　risk。　Imagine　that　in　a　generation　we　characterize　the　orbits　of　30；000　objects　of　100…meter　diameter　or　more；　and　that　this　information　is　publicized；　as　of　course　it　should　be。　Maps　will　be　published　showing　near…Earth　space　black　with　the　orbits　of　asteroids　and　ets；　30；000　swords　of　Damocles　hanging　over　our　heads…ten　times　more　than　the　number　of　stars　visible　to　the　naked　eye　under　conditions　of　optimum　atmospheric　clarity。　Public　anxiety　might　be　much　greater　in　such　a　time　of　knowledge　than　in　our　current　age　of　ignorance。　There　might　be　irresistible　public　pressure　to　develop　means　to　mitigate　even　nonexistent　threats；　which　would　then　feed　the　danger　that　deflection　technology　would　be　misused。　For　this　reason；　asteroid　discovery　and　surveillance　may　not　be　a　mere　neutral　tool　of　future　policy；　but　rather　a　kind　of　booby　trap。　To　me；　the　only　foreseeable　solution　is　a　bination　of　accurate　orbit　estimation；　realistic　threat　assessment；　and　effective　public　education—so　that　in　democracies　at　least；　the　citizens　can　make　their　own；　informed　decisions。　This　is　a　job　for　NASA。

Near…Earth　asteroids；　and　means　of　altering　their　orbits；　are　being　looked　at　seriously。　There　is　some　sign　that　officials　in　the　Department　of　Defense　and　the　weapons　laboratories　are　beginning　to　understand　that　there　may　be　real　dangers　in　planning　to　push　asteroids　around。　Civilian　and　military　scientists　have　met　to　discuss　the　subject。　On　first　hearing　about　the　asteroid　hazard；　many　people　think　of　it　as　a　kind　of　Chicken　Little　fable；　Goosey…Lucy；　newly　arrived　and　in　great　excitement；　is　municating　the　urgent　news　that　the　sky　is　falling。　The　tendency　to　dismiss　the　prospect　of　any　catastrophe　that　we　have　not　personally　witnessed　is　in　the　long　run　very　foolish。　But　in　this　case　it　may　be　an　ally　of　prudence。



MEANWHILE　WE　MUST　STILL　FACE　the　deflection　dilemma。　If　we　develop　and　deploy　this　technology；　it　may　do　us　in。　If　we　don't；　some　asteroid　or　et　may　do　us　in。　The　resolution　of　the　dilemma　hinges；　I　think；　on　the　fact　that　the　likely　timescales　of　the　two　dangers　are　very　different—short　for　the　former；　long　for　the　latter。

I　like　to　think　that　our　future　involvement　with　near…Earth　asteroids　will　go　something　like　this：　From　ground…based　observatories；　we　discover　all　the　big　ones；　plot　and　monitor　their　orbits；　determine　rotation　rates　and　positions。　Scientists　are　diligent　in　explaining　the　dangers—neither　exaggerating　nor　muting　the　prospects。　We　send　robotic　spacecraft　to　fly　by　a　few　selected　bodies；　orbit　them；　land　on　them；　and　return　surface　samples　to　laboratories　on　Earth。　Eventually　we　send　humans。　（Because　of　the　low　gravities；　they　will　be　able　to　make　standing　broad　jumps　of　ten　kilometers　or　more　into　the　sky；　and　lob　a　baseball　into　orbit　around　the　asteroid。）　Fully　aware　of　the　dangers；　we　make　no　attempts　to　alter　trajectories　until　the　potential　for　misuse　of　world…altering　technologies　is　much　less。　That　might　take　a　while。

If　we're　too　quick　in　developing　the　technology　to　move　worlds　around；　we　may　destroy　ourselves；　if　we're　too　slow；　we　will　surely　destroy　ourselves。　The　reliability　of　world　political　organizations　and　the　confidence　they　inspire　will　have　to　make　significant　strides　before　they　can　be　trusted　to　deal　with　a　problem　of　this　seriousness。　At　the　same　time；　there　seems　to　be　no　acceptable　national　solution。　Who　would　feel　fortable　with　the　means　of　world　destruction　in　the　hands　of　some　dedicated　（or　even　potential）　enemy　nation；　whether　or　not　our　nation　had　parable　powers？　The　existence　of　interplanetary　collision　hazards；　when　widely　understood；　works　to　bring　our　species　together。　When　facing　a　mon　danger；　we　humans　have　sometimes　reached　heights　widely　thought　impossible；　we　have　set　aside　our　differences—at　least　until　the　danger　passed。

But　this　danger　never　passes。　The　asteroids；　gravitationally　churning；　are　slowly　altering　their　orbits；　without　warning；　new　ets　e　careening　toward　us　from　the　transplutonian　darkness。　There　will　always　be　a　need　to　deal　with　them　in　a　way　that　does　not　endanger　us。　By　posing　two　different　classes　of　peril—one　natural；　the　other　human…made—the　small　near…Earth　worlds　provide　a　new　and　potent　motivation　to　create　effective　transnational　institutions　and　to　unify　the　human　species。　It's　hard　to　see　any　satisfactory　alternative。