IS THERE INTELLIGENT LIFE ON EARTH? 



275 



HELIUM 



$25 per 1000 ft 3 



HELIUM (70+) (20) 



$8 per long ton 



COAL (44) (18) 



FUELS 



$3.40 per barrel 

 55«!per 1000 ft 3 



$30 per lb U 3 Og 



CRUDE PETROLEUM (33) (18) 

 mm NATURAL GAS (63) (16) 



URANIUM 235 (50±) (7) 



$23.40 per ton 



$53 per long ton 



10x reserves exhausted 2239 

 IRON (28) (39) 



i MANGANESE (14) (29) 



$60 per short ton chromium in ore concentrate 



IRON AND ^mmmmm^M 

 IRON-ALLOY Q^peMb , 



METALS $1.62 per Ibi 



CH ROMIU M 

 (19) (27) 



$63 per lb W0 3 

 $1.85 per lb| 



NICKEL (38) (21) 

  MOLYBDENUM (40) (17) 

 i TUNGSTEN (22) (21) 



iCOBALT (32) (44) 



r 



384 per lb i 



NON- 



FERROUS 2 7«!perlb I 



INDUSTRIAL 



$1.90 per lb 

 METALS 



COPPER (33) (16) 

 LEAD (25) (25) 



ZINC (26) (29) 



mmmTIN (24) (64) 



324 per lb ' 



ALUMINUM (42) (12) 



PRECIOUS 

 METALS 



$145 per troy oz 



$3.50 per troy oz 



Varying price 

 I 

 $1500 per 76-lb flask 



i GOLD (26) (39) 



SILVER (26) (27) 



Hi PLATINUM (31) (21) 



MERCURY (24) (29) 

 J I 



1968 



2000 



2050 2100 



YEAR 



2150 



2200 



Fig. 6 Apparent lifetimes of optimistically estimated "reserves" of mineral 

 commodities at expected rates of demand to year 2000. Solid line at left 

 shows reserves at indicated prices (1968 dollars); dotted line at left indicates 

 5x these reserves; solid line at right indicates lOx estimated reserves. Numbers 

 in parentheses are percentages of current world consumption by the United 

 States (left) and current doubling rates of global consumption. Data from 

 Mineral Facts and Problems, 4th ed., U. S. Bureau of Mines, 1970. 



safeguard people and their environment against the substantial hazards of fission 

 energy until contained fusion reactors become a reality. 



What are the chances of increasing the reserves of now limited resources by 

 more than an order of magnitude above those now known, and what would we 

 gain or lose by doing so? What do we do to stretch the limits — to remain within 



