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oreseen　that　the　Cold　War　would　sell　the　Moon。　But　he　did　recognize　that　an　honest　profit　argument　would　be　difficult　to　e　by。　Heinlein　envisioned；　therefore；　a　scam　in　which　the　lunar　surface　was　salted　with　diamonds　so　later　explorers　could　breathlessly　discover　them　and　initiate　a　diamond　rush。　We've　since　returned　samples　from　the　Moon；　though；　and　there　is　not　a　hint　of　mercially　interesting　diamonds　there。

However；　Kiyoshi　Kuramoto　and　Takafumi　Matsui　of　the　University　of　Tokyo　have　studied　how　the　central　iron　cores　of　Earth；　Venus；　and　Mars　formed；　and　find　that　the　Martian　mantle　（between　crust　and　core）　should　be　rich　in　carbon—richer　than　that　of　the　Moon　or　Venus　or　Earth。　Deeper　than　300　kilometers；　the　pressures　should　transform　carbon　into　diamond。　We　know　that　Mars　has　been　geologically　active　over　its　history。　Material　from　great　depth　will　occasionally　be　extruded　up　to　the　surface；　and　not　just　in　the　great　volcanos。　So　there　does　seem　to　be　a　case　for　diamonds　on　other　worlds—on　Mars；　lied　not　the　Moon。　In　what　quantities；　of　what　quality　and　size；　and　in　which　locales　we　do　not　yet　know。

The　return　to　Earth　of　a　spacecraft　stuffed　with　gorgeous　multicarat　diamonds　would　doubtless　depress　prices　（as　well　as　the　shareholders　of　the　de　Beers　and　General　Electric　corporations）。　But　because　of　the　ornamental　and　industrial　applications　of　diamonds；　perhaps　there　is　a　lower　limit　below　which　prices　will　not　go。　Conceivably；　the　affected　industries　might　find　cause　to　promote　the　early　exploration　of　Mars。

The　idea　that　Martian　diamonds　will　pay　for　exploring　Mars　is　at　best　a　very　long　shot；　but　it's　an　example　of　how　rare　and　valuable　substances　may　be　discoverable　on　other　worlds。　It　would　be　foolish；　though；　to　count　on　such　contingencies。　If　we　seek　to　justify　missions　to　other　worlds；　we'll　have　to　find　other　reasons。



BEYOND　DISCUSSIONS　OF　PROFITS　and　costs；　even　reduced　costs；　we　must　also　describe　benefits；　if　they　exist。　Advocates　of　human　missions　to　Mars　must　address　whether；　in　the　long　term；　missions　up　there　are　likely　to　mitigate　any　of　the　problems　down　here。　Consider　now　the　standard　set　of　justifications　and　see　if　you　find　them　valid；　invalid；　or　indeterminate：

Human　missions　to　Mars　would　spectacularly　improve　our　knowledge　of　the　planet；　including　the　search　for　present　and　past　life。　The　program　is　likely　to　clarify　our　understanding　of　the　environment　of　our　own　planet；　as　robotic　missions　have　already　begun　to　do。　The　history　of　our　civilization　shows　that　the　pursuit　of　basic　knowledge　is　the　way　the　most　significant　practical　advances　e　about。　Opinion　polls　suggest　that　the　most　popular　reason　for　〃exploring　space〃　is　〃increased　knowledge。〃　But　are　humans　in　space　essential　to　achieve　this　goal？　Robotic　missions；　given　high　national　priority　and　equipped　with　improved　machine　intelligence；　seem　to　me　entirely　capable　of　answering；　as　well　as　astronauts　can；　all　the　questions　we　need　to　ask—and　at　Maybe　10　percent　the　cost。

It　is　alleged　that　〃spinoff〃　will　transpire—huge　technological　benefits　that　would　otherwise　fail　to　e　about—thereby　improving　our　international　petitiveness　and　the　domestic　economy。　But　this　is　an　old　argument：　Spend　80　billion　（in　contemporary　money）　to　send　Apollo　astronauts　to　the　Moon；　and　we'll　throw　in　a　free　stickless　frying　pan。　Plainly；　if　we're　after　frying　pans；　we　can　invest　the　money　directly　and　save　almost　all　of　that　80　billion。

The　argument　is　specious　for　other　reasons　as　well；　one　of　which　is　that　DuPont's　Teflon　technology　long　antedated　Apollo。　The　same　is　true　of　cardiac　pacemakers；　ballpoint　pens；　Velcro；　and　other　purported　spinoffs　of　the　Apollo　program。　（I　once　had　the　opportunity　to　talk　with　the　inventor　of　the　cardiac　pacemaker；　who　himself　nearly　had　a　coronary　accident　describing　the　injustice　of　what　he　perceived　as　NASA　taking　credit　for　his　device。）　If　there　are　technologies　we　urgently　need；　then　spend　the　money　and　develop　them。　Why　go　to　Mars　to　do　it？

Of　course　it　would　be　impossible　for　so　much　new　technology　as　NASA　requires　to　be　developed　and　not　have　some　spillover　into　the　general　economy；　some　inventions　useful　down　here。　For　example；　the　powdered　orange　juice　substitute　Tang　was　a　product　of　the　manned　space　program；　and　spinoffs　have　occurred　in　cordless　tools；　implanted　cardiac　defibrillators；　liquid…cooled　garments；　and　digital　imaging—to　name　a　few。　But　they　hardly　justify　human　voyages　to　Mars　or　the　existence　of　NASA。

We　could　see　the　old　spinoff　engine　wheezing　and　puffing　in　the　waning　days　of　the　Reagan…era　Star　Wars　office。　Hydrogen　bomb…driven　X…ray　lasers　on　orbiting　battle　stations　will　help　perfect　laser　surgery；　they　told　us。　But　if　we　need　laser　surgery；　if　it's　a　high　national　priority；　by　all　means　let's　allocate　the　funds　to　develop　it。　just　leave　Star　Wars　out　of　it。　Spinoff　justifications　constitute　an　admission　that　the　program　can't　stand　on　its　own　two　feet；　cannot　be　justified　by　the　purpose　for　which　it　was　originally　sold。

Once　upon　a　time　it　was　thought；　on　the　basis　of　econometric　models；　that　for　every　dollar　invested　in　NASA　many　dollars　were　pumped　into　the　U。S。　economy。　If　this　multiplier　effect　applied　more　to　NASA　than　to　most　government　agencies；　it　would　provide　a　potent　fiscal　and　social　justification　for　the　space　program。　NASA　supporters　were　not　shy　about　appealing　to　this　argument。　But　a　1994　Congressional　Budget　Office　study　found　it　to　be　a　delusion。　While　NASA　spending　benefits　some　production　segments　of　the　U。S。　economy—especially　the　aerospace　industry—there　is　no　preferential　multiplier　effect。　Likewise；　while　NASA　spending　certainly　creates　or　maintains　jobs　and　profits；　it　does　so　no　more　efficiently　than　many　other　government　agencies。

Then　there's　education；　an　argument　that　has　proved　from　time　to　time　very　attractive　in　the　White　House。　Doctorates　in　science　peaked　somewhere　around　the　time　of　Apollo　11；　maybe　even　with　the　proper　phase　lag　after　the　start　of　the　Apollo　program。　The　cause…and…effect　relationship　is　perhaps　undemonstrated；　although　not　implausible。　But　so　what？　If　we're　interested　in　improving　education；　is　going　to　Mars　the　best　route？　Think　of　what　we　could　do　with　100　billion　for　teacher　training　and　salaries；　school　laboratories　and　libraries；　scholarships　for　disadvantaged　students；　research　facilities；　and　graduate　fellowships。　Is　it　really　true　that　the　best　way　to　promote　science　education　is　to　go　to　Mars？

Another　argument　is　that　human　missions　to　Mars　will　occupy　the　military…industrial　plex；　diffusing　the　temptation　to　use　its　considerable　political　muscle　to　exaggerate　external　threats　and　pump　up　defense　funding。　The　other　side　of　this　particular　coin　is　that　by　going　to　Mars　we　maintain　a　standby　technological　capacity　that　might　be　important　for　future　military　contingencies。　Of　course；　we　might　simply　ask　those　guys　to　do　something　directly　useful　for　the　civilian　economy。　But　as　we　saw　in　the　1970s　with　Grumman　buses　and　Boeing/Vertol　muter　trains；　the　aerospace　industry　experiences　real　difficulty　in　producing　petitively　for　the　civilian　economy。　Certainly　a　tank　may　travel　1；000　miles　a　year　and　a　bus　1；000　miles　a　week；　so　the　basic　designs　must　be　different。　But　on　matters　of　reliability　at　least；　the　Defense　Department　seems　to　be　much　less　demanding。

Cooperation　in　space；　as　I've　already　mentioned；　is　being　an　instrument　of　international　cooperation—for　example；　in　slowing　the　proliferation　of　strategic　weapons　to　new　nations。　Rockets　demissioned　because　of　the　end　of　the　Cold　War　might　be　gainfully　employed　in　missions　to　Earth　orbit；　the　Moon；　the　planets；　asteroids；　and　ets。　But　all　this　can　be　acplished　without　human　missions　to　Mars。

Other　justifications　are　offered。　It　is　argued　that　the　ultimate　solution　to　world　energy　problems　is　to　strip…mine　the　Moon；　return　the　solar…wind…implanted　helium…3　back　to　Earth；　and　use　it　in　fusion　reactors。　What　fusion　reactors？　Even　if　this　were　possible；　even　if　it　were　cost…effective；　it　is　a　technology　50　or　100　years　away。　Our　energy　problems　need　to　be　solved　at　a　less　leisurely　pace。

Even　stranger　is　the　argument　that　we　have　to　send　human　beings　into　space　in　order　to　solve　the　world　population　crisis。　But　some　250；000　more　people　are　born　than　die　every　day—

which　means　cans　that　we　would　have　to　launch　250；000　people　per　day　into　space　to　maintain　world　population　at　its　present　levels。　This　appears　to　be　beyond　our　present　capability。



I　RUN　THROUGH　such　a　list　and　try　to　add　up　the　pros　and　cons；　bearing　in　mind　the　other　urgent　claims　on　the　federal　budget。　To　me；　the　argument　so　far　es　down　to　this　question：　Can　the　sum　of　a　large　number　of　individually　inadequate　Justifications　add　up　to　an　adequate　justification？

I　don't　think　any　of　the　items　on　my　list　of　purported　justifications　is　demonstrably　worth　500　billion　or　even　100　billion；　certainly　not　in　the　short　term。　On　the　other　hand；　most　of　them　are　worth　something；　and　if　I　have　five　items　each　worth　20　billion；　maybe　it　adds　up　to　100　billion。　If　we　can　be　clever　about　reducing　costs　and　making　true　international　partnerships；　the　justifications　bee　mo